JPH08129315A - Electro-magnetic induction type fixing device - Google Patents

Abstract

PURPOSE: To provide an electro-magnetic induction type fixing device of novel constitution which is capable of preventing the flow of the current by electromagnetic induction to the journals, bearings, gears, pulleys, etc., of a fixing roller and does not hinder the function as a fixing device even if metals are used as the materials of these members. CONSTITUTION: This electromagnetic induction type fixing device has the fixing roller 1 as secondary coil and includes a magnetic circuit interlinking with the fixing roller 1, a primary coil 4 interlinking with this magnetic circuit and a power source for feeding power to this primary coil 4. The magnetic circuit described above consists of a magnetic circuit 6 in the fixing roller, a magnetic circuit 3 passing the inside of the primary coil and a magnetical coupling part 7. The magnetic circuit 6 in the fixing roller is rotationally driven together with the fixing roller 1 and both ends of the magnetic circuit 6 in the fixing roller faces a member 7 constituting the magnetic circuit (the magnetic circuit 3 passing the inside of the primary coil and the magnetical coupling part 7) outside the fixing roller in the state that a gap 5 is not changed by rotation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a printer and a facsimile, and more particularly to an electromagnetic induction fixing device for heating by an electromagnetic induction system.

[0002]

2. Description of the Related Art A fixing device of a type is known in which a current is applied to a fixing roller forming a secondary coil by electromagnetic induction to generate heat due to resistance loss to obtain energy necessary for fixing and fixing is performed (for example, a fixing device). JP-A-58-35568).

[0003]

In the conventional electromagnetic induction type fixing device, the fixing roller journal, bearings, gears, pulleys and the like attached thereto are magnetic like the conductors forming the secondary circuit of the fixing roller. It will interlink with the loop of the magnetic circuit composed of the material. If members such as these journals and bearings are made of a conductor such as metal, current flows and energy is supplied in the same manner as the conductor forming the secondary circuit of the fixing roller. Not only these are energy that does not contribute to fixing, but if the resistance of these members is smaller than the resistance of the fixing roller, more current will flow, and it will not even be possible to heat the fixing roller.

Therefore, when these members are made of an insulating material such as ceramics or plastics, or when a good conductor such as metal is used, a slit of an insulating material is formed so that a closed loop interlinking with the magnetic circuit cannot be formed. You must take measures such as. However, plastics often cause problems in terms of heat resistance and strength, and ceramics and the like have problems such as weakness in cost and impact.

The present invention has been made in view of the above circumstances, and relates to an improvement of a fixing device for heating by an electromagnetic induction system. And claims 1 to 11 of the present application
The main purpose common to all the inventions is to enable the use of metal as a material for the journals, bearings, gears, pulleys, etc. of fixing rollers of the electromagnetic induction type. After confirming that this common object is the basis, the object of the invention corresponding to each claim is described below.

An object of the present invention is to enable the use of metal as a material for the journal, bearing, gear, pulley and the like of an electromagnetic induction type fixing roller.

It is an object of the present invention to make it easy to attach the journal portion to the fixing roller and to facilitate magnetic coupling with a magnetic circuit outside the fixing roller.

An object of the present invention is to facilitate the attachment of the journal portion to the fixing roller, facilitate magnetic coupling with a magnetic circuit outside the fixing roller, and to fix the inside of the fixing roller. The objective is to simplify the shape of the magnetic path to facilitate manufacturing, and to use a shaft that penetrates the inside of the fixing roller as a journal.

An object of the present invention is to facilitate magnetic coupling with a magnetic circuit outside the fixing roller even during rotation of the fixing roller.

An object of the present invention is to facilitate magnetic coupling between a magnetic circuit inside the fixing roller and a magnetic circuit outside the fixing roller.

An object of the present invention is to facilitate magnetic coupling between the magnetic circuit inside the fixing roller and the magnetic circuit outside the fixing roller.

It is an object of the present invention to facilitate magnetic coupling between the magnetic circuit inside the fixing roller and the magnetic circuit outside the fixing roller, and to reduce the cross-sectional area of the magnetic circuit at the joint portion. It is to prevent.

It is an object of the present invention to facilitate magnetic coupling between a magnetic circuit inside the fixing roller and a magnetic circuit outside the fixing roller, and also to cause eccentricity of the fixing roller or a magnetic circuit inside and outside the fixing roller. It is to prevent the reduction of the cross-sectional area of the magnetic circuit at the coupling portion while maintaining the good coupling of the magnetic circuit against the positional displacement between the circuits.

An object of the present invention is to prevent the journal portion of the fixing roller from interlinking with the magnetic circuit.
This is to allow the journal portion and the bearings, gears, pulleys, etc. attached to it to be made of a metal material.

The object of the invention described in claim 10 is to secure a space for installing a journal portion and bearings, gears, pulleys and the like to be attached thereto, and to guide a magnetic flux so that these members do not interlink with a magnetic circuit. Is.

An object of the present invention is to provide a magnetic circuit which is excellent in respect of a change in length and variation of a magnetic circuit inside the fixing roller and a magnetic circuit outside the fixing roller due to temperature expansion and manufacturing factors. Is to form a loop. Incidentally, the problem to be solved by the structure of the present claim exists also in the electromagnetic induction type fixing device of the conventional example, and can be applied similarly to the present application, and the solution is also included in the object of the present claim. is there.

[0017]

In order to achieve the above object, the invention according to claim 1 uses a fixing roller as a secondary coil, and a magnetic circuit interlinking with the fixing roller and the magnetic circuit interlinking with the magnetic circuit. In an electromagnetic induction type fixing device including a primary coil and a power supply for supplying power to the primary coil, the magnetic circuit includes a magnetic circuit inside the fixing roller, a magnetic circuit passing through the inside of the primary coil, and a magnetic coupling portion. The magnetic circuit inside the roller is driven to rotate together with the fixing roller,
At both ends of the magnetic circuit inside the fixing roller, a magnetic circuit outside the fixing roller (a magnetic circuit passing through the inside of the primary coil and a magnetic coupling portion) is formed such that the gap does not change due to rotation.
It is characterized in that it is opposed to the member constituting the.

According to a second aspect of the invention, in the electromagnetic induction fixing device according to the first aspect, at least both ends of the magnetic circuit inside the fixing roller are cylindrical.

According to a third aspect of the present invention, in the electromagnetic induction fixing device according to the first aspect, the magnetic circuit inside the fixing roller is cylindrical.

The invention according to claim 4 is the invention as defined in claims 1, 2, and 3.
In the electromagnetic induction-type fixing device described above, both ends of the magnetic circuit inside the fixing roller are in a plane perpendicular to the central axis of rotation of the fixing roller.

The invention according to claim 5 is the invention as claimed in claim 1,
In the electromagnetic induction type fixing devices described in 3 and 4, both ends of the magnetic circuit inside the fixing roller are projected to the outside from the ends of the secondary coil.

According to a sixth aspect of the present invention, in the electromagnetic induction type fixing device according to the fourth aspect, the surface of the magnetic circuit outside the fixing roller that faces the magnetic circuit inside the fixing roller is the magnetic circuit inside the fixing roller. It is characterized by being in a plane parallel to the plane formed by the edges.

According to a seventh aspect of the present invention, in the electromagnetic induction type fixing device according to the sixth aspect, at least a surface of the magnetic circuit outside the fixing roller facing the magnetic circuit inside the fixing roller is at least the magnetic circuit inside the fixing roller. Is characterized in that it has a surface opposed to the entire surface formed by the end of.

According to an eighth aspect of the invention, in the electromagnetic induction type fixing device according to the sixth aspect, at least a surface of the magnetic circuit outside the fixing roller facing the magnetic circuit inside the fixing roller is a magnetic circuit inside the fixing roller. Is characterized in that it has a surface opposed to the entire surface formed by the end of, and has a spread to the periphery in the same plane.

According to a ninth aspect of the invention, in the electromagnetic induction type fixing device according to the first to eighth aspects, the journal portion of the fixing roller is fixed to the secondary coil through a member forming a magnetic circuit inside the fixing roller. It is characterized by being.

According to a tenth aspect of the present invention, in the electromagnetic induction fixing device according to the first to ninth aspects, among the members constituting the magnetic closed loop together with the magnetic circuit inside the fixing roller, the magnetic circuit inside the fixing roller is opposed. The member forming the part to be formed is provided with a through hole in the direction of the central axis of the fixing roller.

According to an eleventh aspect of the present invention, the fixing roller is a secondary coil, and a magnetic circuit interlinks with the fixing roller,
In an electromagnetic induction type fixing device comprising a primary coil interlinking with the magnetic circuit and a power supply for supplying power to the primary coil, the magnetic circuit includes a magnetic circuit inside the fixing roller and a magnetic circuit passing through the inside of the primary coil and a magnetic circuit. And a sliding portion that does not change its magnetic coupling with respect to the relative displacement of the magnetic circuit inside the fixing roller and the magnetic circuit passing through the inside of the primary coil in the axial direction of the fixing roller. It is characterized by

[0028]

In the electromagnetic induction type fixing device of the present invention, the fixing roller and the magnetic circuit inside the fixing roller are integrated, and the magnetic circuit made of a fixed magnetic material is used for the magnetic circuit which is rotationally driven together with the fixing roller. The magnetic flux is bypassed by providing such a coupling portion and is coupled to the magnetic circuit outside the fixing roller inside the journal portion. This prevents the journal part from interlinking with the magnetic circuit, so even if the journal part and the bearings, gears, pulleys, etc. attached to it are made of metal, current will not flow and the function of the electromagnetic induction type fixing device will be hindered. There is no.

[0029]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows a structure of a main part of a fixing device in an embodiment common to claim 1 and its dependent claims. The fixing roller 1 includes a conductor cylinder that forms the secondary coil 16 and a release layer that plays an important role in fixing the toner applied to the surface of the secondary coil 16. The inner surface of the secondary coil 16 includes the inside of the fixing roller. The magnetic material forming the magnetic circuit 6 is integrated. Further, the journals 8 and 9 are fixed via the magnetic circuit 6. The fixing roller 1 is a bearing (not shown) attached to the journals 8 and 9.
It is fixed to the image forming apparatus by a gear or the like, and when fixing an unfixed toner image on the transfer paper, it is driven by a driving source (not shown).

The backup roller 2 is a roller having a soft layer of silicon rubber or the like on the surface thereof, and journals 10 and 11 are attached to both ends thereof similarly to the fixing roller 1. The backup roller 2 has a function of rotating the image surface of the transfer sheet to be fixed on the fixing roller 1 with a predetermined force while rotating the image surface of the transfer paper at a speed substantially equal to that of the fixing roller 1. Therefore, a force is applied to the shaft of the backup roller 2 in the direction of the fixing roller 1. The backup roller 2 is a roller having the same structure as a pressure roller of a conventional roller fixing device of the electromagnetic induction type or other types. Further, at the time of fixing, the toner image on the transfer paper is heated when passing between the rotating fixing roller 1 and the backup roller 2, and the toner is pressed against the transfer paper to be fixed.

The magnetic circuit 3 outside the fixing roller is magnetically coupled to the magnetic material (magnetic circuit) penetrating the inside of the primary coil 4 and both ends of the magnetic circuit 6 inside the fixing roller. And a magnetic circuit 6 inside the fixing roller, and constitutes a magnetic circuit for one circuit. Therefore,
When the primary coil 4 is excited by an AC power supply (not shown), a magnetic flux is formed in the loop of this magnetic circuit, and the secondary coil of the fixing roller 1 (which is configured to interlink with this magnetic flux Electric current flows through the cylindrical part).

In such a magnetic circuit configuration, the journals 8 and 9 of the fixing roller 1 and the bearings, gears and the like (not shown) attached to the journal are outside the loop of the magnetic circuit and therefore do not interlink with the magnetic flux. Therefore, since the secondary circuit is not configured, current does not flow even if it is made of a conductor such as metal, and the function of the electromagnetic induction fixing device is not fulfilled.
It does not interfere. The detailed functions and shapes of the magnetic coupling portion 7, the magnetic gap 5, and the slide surface 15 of the magnetic circuit will be described in the individual embodiments, and will not be described here.

FIG. 2 shows claims 1 to 7 and claims 9 and 10.
FIG. 6 is a diagram showing details of an end portion of the fixing roller 1 excluding the magnetic coupling portion 7, the magnetic gap 5, and the fixing roller 1 of the embodiment corresponding to FIG.
FIG. 6B is a side view of the main part of the end portion of the fixing device. The backup roller 2 is not shown.

The fixing roller 1 is composed of a magnetic cylinder forming the magnetic circuit 6 inside the fixing roller, a secondary coil 16 formed on the surface of the cylinder, and a release layer applied to the secondary coil 16. Composed. The magnetic body of the cylinder is ferrite,
The secondary coil 16 is a cylinder of aluminum and is fixed to ferrite by adhesion. Further, the secondary circuit can be formed by applying or depositing a conductive material on the surface of the magnetic body.

The magnetic cylinder 6 is formed so as to project from the secondary coil 16 at its end, and the end has a surface lying in a plane perpendicular to the axis of the cylinder. This surface faces the magnetic coupling portion 7 of the magnetic circuit 3 outside the fixing roller via the magnetic gap 5. Since the facing surfaces are perpendicular to the axis of the cylinder, the gap 5 does not change due to the rotation of the fixing roller 1 without providing a special mechanism.

In the magnetic coupling portion 7 of the magnetic circuit 3 outside the fixing roller, a hole having the same diameter as that of the inner surface of the cylinder of the magnetic circuit 6 inside the fixing roller is formed. The thickness of the magnetic material around this hole is thin at the bottom of the figure, and becomes thicker toward the top. In the magnetic gap 5, the magnetic flux of uniform density passes through each portion on the circumference, but the magnetic flux is gathered in the upper part of the figure, so that the magnetic flux increases toward the upper part. Then, the magnetic substance is prevented from being saturated by increasing the thickness of the magnetic body as the magnetic flux increases. Incidentally, it is desirable from the viewpoint of saving the magnetic material that the cross-sectional area of the magnetic body in the direction perpendicular to the direction of the magnetic flux is ensured to be the minimum necessary throughout the entire magnetic circuit. However, it is functionally bad that the saturation of magnetic flux occurs due to the small cross-sectional area in a specific part, but the cross-sectional area of a specific part becomes large in order to secure the mechanical strength or magnetic coupling of the magnetic substance. There is no problem functionally.

The hole of the magnetic coupling portion 7 of the magnetic circuit 3 outside the fixing roller described above allows the journal of the fixing roller 1 to be installed, but the magnetic flux is bypassed and linked with the journal portion. Therefore, even if the journal and the bearings, gears and the like attached thereto are made of a material having low resistance such as metal, no current flows.

Next, FIG. 3 is an improvement of the embodiment of FIG. 2, and FIG. 2 shows another embodiment of the corresponding claim and an embodiment corresponding to claim 8. In this embodiment, the eccentricity of the fixing roller 1 and the magnetic circuit 3 outside the fixing roller 1 are used.
In order to prevent the magnetic flux in the magnetic circuit from being saturated due to a decrease in the facing area of the internal and external magnetic circuits in the magnetic gap 5 due to the positional deviation of
In particular, the magnetic coupling portion 7 is widened downward in the lower part of the figure. This is characterized in that the area of the magnetic coupling portion 7 is increased without reducing the hole of the magnetic coupling portion 7.

Next, FIG. 4 is also an improvement of the embodiment of FIG. 2, and FIG. 2 is a further embodiment of the corresponding claim and another embodiment corresponding to the eighth claim. . The difference between this embodiment and FIG. 3 is that when the area of the coupling portion is widened, it is also widened in the direction in which the diameter of the hole of the magnetic coupling portion 7 becomes smaller. Although some restrictions are imposed on the passage of the journal, there is a large margin for eccentricity and displacement.

FIG. 5 is a diagram showing an embodiment corresponding to claim 11, in which the magnetic circuit 6 inside the fixing roller and the magnetic circuit 3 outside the fixing roller normally differ in temperature rise, and accordingly the length differs. Occurs, which makes it difficult to maintain a magnetic gap, stresses the magnetic material in order to maintain the gap, and prevents the magnetic material from cracking due to stress. A sliding surface 15 as a sliding portion is provided. The sliding surface 15 is a flat surface that slides in response to axial expansion and contraction of the roller, and the contact area does not change even when sliding. Therefore, the magnetic coupling does not change even when sliding.

FIG. 6 is also a view showing another embodiment corresponding to claim 11 in which a cylindrical surface is provided as the sliding portion 15. The present embodiment and the embodiment of FIG. 5 have the same functions as the embodiment of FIG. 5, except that they slide on a cylindrical surface. Of course, the embodiments of FIGS. 5 and 6 can be implemented in combination with the embodiments corresponding to claim 1 and its dependent claims. Although not described in the embodiment of FIG. 1, the sliding surface 15 of the magnetic circuit is shown.

Next, FIG. 7 is a view showing the structure of the fixing roller according to the embodiment of the present invention, showing the details of the magnetic circuit 6 and the secondary coil 16 inside the fixing roller. Since the structure of the fixing roller 1 has already been described, the description thereof is omitted here.

Further, FIG. 8 shows the journals 8 and 9 of the fixing roller 1, the magnetic circuit 6 inside the fixing roller, and the secondary coil 16.
Is a diagram showing the relationship of the above, but since this has already been described, the description thereof will be omitted.

FIG. 9 is a view showing a part of another embodiment showing the relationship between the magnetic circuit 6 inside the fixing roller and the secondary coil 16. In this embodiment, the magnetic material forming the magnetic circuit 6 has a shape in which a groove is formed on the surface of a cylinder, and the secondary coil 16 is provided on the outer peripheral surface thereof. The secondary coil 16 is fixed to a cylinder forming the magnetic circuit 6 by adhering and fixing a key portion thereof, leaving a gap to enhance the heat insulating effect of the secondary coil 16. It is also possible to fill the voids with an adhesive having a high heat insulating effect. Of course, also in this embodiment, the end portion is a flat surface perpendicular to the axis.

Next, FIG. 10 shows another embodiment corresponding to claim 2 in a sectional view. In the present embodiment, an electromagnetic induction type fixing device can be functionally constructed if a magnetic loop having a predetermined cross-sectional area that passes through the inside of the fixing roller 1 due to the characteristics of the magnetic circuit 6 can be constructed. It is shown that it is not necessary to make the magnetic circuit 6 into a cylindrical shape, and only both ends of the magnetic circuit 6 are made into a cylindrical shape.
Of course, the shape is not limited to the shape shown here, and may be any shape as long as a predetermined magnetic loop can be formed.
With such a shape, since a relatively large volume of air is trapped inside the fixing roller 1, when the surface of the roller swells due to thermal expansion and a problem occurs in fixing, an air vent hole is formed in a part of the magnetic circuit. Of course, it is possible.

Next, FIG. 11 shows another embodiment corresponding to claims 1 and 11. In this embodiment, the magnetic circuit 6 in the fixing roller is made of a cylindrical magnetic material, the secondary coil 16 is provided on the surface of the magnetic circuit 6, and a release layer is formed on the surface of the secondary coil 16. Holes are formed in both ends of the magnetic material 6, and the journals 8 and 9 are attached by adhering while positioning the holes by the holes. Further, the magnetic circuit 6 between the journal mounting portion and the secondary coil 16 faces the magnetic coupling portion 7 that magnetically couples on the cylindrical surface, and forms a magnetic loop with the magnetic circuit 3 outside the fixing roller. . The cylindrical magnetic coupling surface can have the function of the sliding surface (sliding portion) of the magnetic circuit described with reference to FIGS. 5 and 6. Therefore, the sliding surface 15 of the magnetic circuit in the figure
Is unnecessary for coping with thermal expansion, but can be separated by a surface which is a slide surface 15 for convenience of attaching a primary coil (not shown) to the magnetic circuit 3 outside the fixing roller in this embodiment. However, it is fixed without sliding.

Next, with respect to the magnetic gap 5 and the slide surface 15 of the magnetic circuit appearing in some embodiments, their magnetic circuit and electric circuit functions will be described. In the electromagnetic induction type fixing device, the primary coil 4 and the secondary coil 16 are coupled via the magnetic flux induced in the magnetic circuit, so that the energy supplied from the primary coil 4 is transmitted to the secondary coil 16 to perform heating. A primary coil 4 and a secondary coil 1
6, the magnetic circuit 3, 6 constitutes a transformer. In a normal transformer, if there is a gap in the magnetic circuit, the leakage magnetic flux increases and the exciting current increases. This is observed as an increase in input current when the secondary circuit of the transformer is opened. When the output of the secondary circuit is used as a voltage source induced by the ratio of the numbers of turns of the primary coil and the secondary coil, an increase in the exciting current due to the leakage flux due to the gap reduces the efficiency of the transformer, which is not preferable. Efforts are being made to minimize the gap in such applications.

Also in the magnetic gap 5 of the present application, it is possible to make the gap small by using an auxiliary positioning mechanism or the like, or by providing a thin sliding member in the gap so as to allow sliding. Can function as a transformer.

However, the secondary coil 16 of the electromagnetic induction type fixing device is a one-turn winding, and the resistance value of one turn in the circumferential direction is often very small, which results in a large current load at a low voltage. Attempting to drive such a load with a voltage source will be greatly affected by changes in the resistance of the load due to temperature characteristics. Rather, it is desirable to drive with a current source in order to drive a large current load at such a low voltage. As a means for driving with a current source, it is also possible to set a gap of the magnetic circuit to a predetermined value to form a leakage transformer. In other words, by actively utilizing the magnetic gap of each embodiment of the present invention, as a leakage transformer,
The secondary coil may be heated.

[0050]

As described above, according to the first aspect of the invention, the magnetic circuit includes the magnetic circuit inside the fixing roller, the magnetic circuit passing through the inside of the primary coil, and the magnetic coupling portion. The magnetic circuit of the fixing roller is driven to rotate together with the fixing roller, and both ends of the magnetic circuit inside the fixing roller are magnetic circuits outside the fixing roller (a magnetic circuit passing through the inside of the primary coil and a magnetic coupling The magnetic circuit inside the fixing roller is integrated with the magnetic circuit inside the fixing roller, and a magnetic material fixed to the magnetic circuit rotated together with the fixing roller is used. By providing a magnetic coupling part that bypasses the magnetic flux and is coupled to the magnetic circuit outside the fixing roller inside the journal part, the journal part becomes magnetic. Since eliminating interlink road and chains, journal and there mounting bearings, gears, also no current flows making such a metal pulley, not to inhibit the function of the fixing device of an electromagnetic induction method. Therefore, according to the present invention, metal can be used as a material for the journal, bearing, gear, pulley, etc. of the fixing roller of the electromagnetic induction type.

According to the second aspect of the present invention, at least both ends of the magnetic circuit inside the fixing roller are cylindrical, so that the journal portion can be easily attached to the fixing roller and the magnetic circuit outside the fixing roller is facilitated. The magnetic coupling with can be facilitated.

According to the third aspect of the invention, since the magnetic circuit inside the fixing roller is cylindrical, it is easy to attach the journal portion to the fixing roller, and the magnetic circuit is external to the magnetic circuit outside the fixing roller. In addition to facilitating easy coupling, the shape of the magnetic path inside the fixing roller can be simplified to facilitate manufacturing, and a shaft that penetrates the inside of the fixing roller can be used as a journal.

According to the fourth aspect of the present invention, both ends of the magnetic circuit inside the fixing roller are in planes perpendicular to the central axis of rotation of the fixing roller, so that the outside of the fixing roller is kept outside even while the fixing roller is rotating. The magnetic coupling with the magnetic circuit can be facilitated.

According to the fifth aspect of the present invention, both ends of the magnetic circuit inside the fixing roller protrude outside the ends of the secondary coil, so that the magnetic circuit inside the fixing roller and the magnetic circuit outside the fixing roller are provided. The magnetic coupling with can be facilitated.

In the sixth aspect of the present invention, the surface of the magnetic circuit outside the fixing roller that faces the magnetic circuit inside the fixing roller is in a plane parallel to the surface formed by the end of the magnetic circuit inside the fixing roller. This facilitates magnetic coupling between the magnetic circuit inside the fixing roller and the magnetic circuit outside the fixing roller.

In the seventh aspect of the invention, the surface of the magnetic circuit outside the fixing roller facing the magnetic circuit inside the fixing roller faces at least the entire surface formed by the end of the magnetic circuit inside the fixing roller. By having the surface, it is possible to facilitate magnetic coupling between the magnetic circuit inside the fixing roller and the magnetic circuit outside the fixing roller, and prevent reduction in the cross-sectional area of the magnetic circuit at the coupling portion.

According to the present invention, the surface of the magnetic circuit outside the fixing roller that faces the magnetic circuit inside the fixing roller faces at least the entire surface formed by the end of the magnetic circuit inside the fixing roller. By having a surface and spreading to the periphery in the same plane, magnetic coupling between the magnetic circuit inside the fixing roller and the magnetic circuit outside the fixing roller is facilitated, and the eccentricity or inside of the fixing roller It is possible to maintain good coupling of the magnetic circuits and prevent a reduction in the cross-sectional area of the magnetic circuits at the coupling portion even with respect to the positional deviation between the external magnetic circuit and the external magnetic circuit.

According to the invention of claim 9, the journal portion of the fixing roller is fixed to the secondary coil through a member forming a magnetic circuit inside the fixing roller,
The journal part of the fixing roller should not be linked to the magnetic circuit, and the journal part and the bearings, gears attached to it,
The pulley or the like can be made of a metal material.

According to the tenth aspect of the invention, among the members forming the magnetic closed loop together with the magnetic circuit inside the fixing roller, the member forming the portion facing the magnetic circuit inside the fixing roller is the central axis of the fixing roller. By providing the through hole in the direction, it is possible to secure a space for installing the journal portion and bearings, gears, pulleys, etc. attached to the journal portion, and to guide the magnetic flux so that these members do not interlink with the magnetic circuit. .

In the eleventh aspect of the invention, the magnetic circuit comprises a magnetic circuit inside the fixing roller, a magnetic circuit passing through the inside of the primary coil, and a magnetic coupling portion, and the magnetic circuit inside the fixing roller and the inside of the primary coil are connected to each other. By providing a sliding portion whose magnetic coupling does not change with respect to the relative displacement of the passing magnetic circuit in the axial direction of the fixing roller, the magnetic circuit inside the fixing roller and the magnetic circuit outside the fixing roller are provided. The loop of the magnetic circuit can be favorably formed even if the length changes or varies due to temperature expansion or manufacturing factors.

As described above, in the inventions according to claims 1 to 11, since metal journals, bearings, gears, pulleys, etc. can be used, material cost, processing cost, utilization of general-purpose parts, etc. are common. Benefits are obtained.

Further, as an additional effect, since the magnetic circuit is bypassed inside the journal portion, the required magnetic circuit becomes shorter than the prior art, and the magnetic material can be saved and the device can be downsized. it can.

As another additional effect, since the magnetic circuit inside the fixing roller reinforces the secondary coil, which is the heat generating portion of the fixing roller, from the back side, it is advantageous to make the secondary coil thin. There is no restriction, the heat capacity of the heat generating portion can be reduced, and the temperature of the fixing device can be raised quickly.

As another additional effect, since the fixing roller does not have a heating lamp, a magnetic circuit, or the like, which is a separate member from the roller, it is possible to make a thin fixing roller, which makes the apparatus compact and lightweight. Can be achieved.

As a further additional effect, since the magnetic circuit is provided with a gap, it becomes easy to assemble the apparatus or assemble it into the image forming apparatus and maintain it.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of a main part of an electromagnetic induction fixing device according to an exemplary embodiment of the present invention.

2A and 2B are views showing a structure of a magnetic coupling portion according to an embodiment of the present invention, FIG. 2A is a front view of a main portion of an end portion of a fixing device, and FIG.
FIG. 3 is a side view of a main portion of an end portion of the fixing device.

FIG. 3 is a diagram showing a structure of a magnetic coupling portion according to another embodiment of the present invention, in which (a) is a front view of a main portion of an end portion of a fixing device;
FIG. 6B is a side view of the main part of the end portion of the fixing device.

4A and 4B are views showing a structure of a magnetic coupling portion according to still another embodiment of the present invention, wherein FIG. 4A is a front view of a main portion of an end portion of a fixing device, and FIG. FIG.

5A and 5B are views showing a structure of a sliding surface of a magnetic circuit according to an embodiment of the present invention, in which FIG. 5A is a front view of a main portion of an end portion of the fixing device, and FIG. It is a figure.

6A and 6B are views showing a structure of a sliding surface of a magnetic circuit according to another embodiment of the present invention, in which FIG. 6A is a front view of a main portion of an end portion of the fixing device, and FIG. FIG.

7A and 7B are diagrams showing a structure of a fixing roller of an embodiment of the present invention, FIG. 7A is a front view of an end portion of the fixing roller, and FIG. 7B is a side view of the end portion of the fixing roller.

FIG. 8 is a side view of the fixing roller end portion showing the structure of the journal portion according to the embodiment of the invention.

FIG. 9 is a partial cross-sectional view of a fixing roller showing a structure of a fixing roller of another embodiment of the present invention.

FIG. 10 is a side view of an end portion of a fixing roller showing a structure of a fixing roller according to still another embodiment of the present invention.

11A and 11B are diagrams showing a configuration of a main part of an electromagnetic induction type fixing device according to another embodiment of the present invention, wherein FIG. 11A is a front view of a main part of an end part of the fixing device, and FIG. 11B is an end part of the fixing device. It is a principal part side view of FIG.

[Explanation of symbols]

 1: Fixing roller 2: Backup roller 3: Magnetic circuit outside fixing roller 4: Primary coil 5: Magnetic gap 6: Magnetic circuit inside fixing roller 7: Magnetic coupling part 8, 6: Journal of fixing roller 10, 11 : Journal of backup roller 15: Slide surface of magnetic circuit 16: Secondary coil

Claims (11)

[Claims] 1. An electromagnetic induction type fixing device comprising a fixing roller as a secondary coil, a magnetic circuit interlinking with the fixing roller, a primary coil interlinking with the magnetic circuit, and a power supply for supplying power to the primary coil. In, the magnetic circuit comprises a magnetic circuit inside the fixing roller, a magnetic circuit passing through the inside of the primary coil, and a magnetic coupling portion, and the magnetic circuit inside the fixing roller is rotationally driven together with the fixing roller, Both ends of the magnetic circuit are opposed to members constituting a magnetic circuit (a magnetic circuit passing through the inside of the primary coil and a magnetic coupling portion) outside the fixing roller in such a manner that the gap does not change due to rotation. Induction type fixing device. 2. The electromagnetic induction fixing device according to claim 1, wherein at least both ends of the magnetic circuit inside the fixing roller are cylindrical. 3. The electromagnetic induction fixing device according to claim 1, wherein the magnetic circuit inside the fixing roller is cylindrical. 4. The electromagnetic induction type fixing device according to claim 1, wherein both ends of the magnetic circuit inside the fixing roller are in a plane perpendicular to the central axis of rotation of the fixing roller. Electromagnetic induction type fixing device. 5. The electromagnetic induction fixing device according to claim 1, 2, 3, or 4, wherein both ends of a magnetic circuit inside the fixing roller are
An electromagnetic induction type fixing device characterized in that it projects outward from the end of the secondary coil. 6. The electromagnetic induction fixing device according to claim 4, wherein the surface of the magnetic circuit outside the fixing roller that faces the magnetic circuit inside the fixing roller is the surface formed by the end of the magnetic circuit inside the fixing roller. An electromagnetic induction type fixing device characterized by being in parallel planes. 7. The electromagnetic induction fixing device according to claim 6, wherein the surface of the magnetic circuit outside the fixing roller that faces the magnetic circuit inside the fixing roller is formed at least by the end of the magnetic circuit inside the fixing roller. An electromagnetic induction type fixing device characterized by having surfaces facing each other. 8. The electromagnetic induction fixing device according to claim 6, wherein the surface of the magnetic circuit outside the fixing roller facing the magnetic circuit inside the fixing roller is formed at least by the end of the magnetic circuit inside the fixing roller. An electromagnetic induction-type fixing device, which has surfaces facing each other and spreads to the periphery in the same plane. 9. The electromagnetic induction fixing device according to claim 1, wherein the journal portion of the fixing roller is fixed to the secondary coil via a member forming a magnetic circuit inside the fixing roller. Electromagnetic induction type fixing device. 10. The electromagnetic induction type fixing device according to claim 1, wherein a member forming a magnetic closed loop together with the magnetic circuit inside the fixing roller constitutes a part facing the magnetic circuit inside the fixing roller. The electromagnetic induction fixing device is characterized in that it has a through hole extending in the direction of the central axis of the fixing roller. 11. An electromagnetic induction fixing device comprising a fixing roller as a secondary coil, a magnetic circuit interlinking with the fixing roller, a primary coil interlinking with the magnetic circuit, and a power supply for supplying power to the primary coil. In the above, the magnetic circuit comprises a magnetic circuit inside the fixing roller, a magnetic circuit passing through the inside of the primary coil, and a magnetic coupling portion, and a shaft of the fixing roller of the magnetic circuit inside the fixing roller and the magnetic circuit passing through the inside of the primary coil. An electromagnetic induction-type fixing device comprising a sliding portion whose magnetic coupling does not change with respect to relative displacement in the direction.