JP3365223B2 - Induction heating fixing device - Google Patents

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, for example, an electrophotographic copying machine, a printer and a facsimile, and more specifically, a fixing device for fixing a toner image on a recording medium by using induction heating. Regarding

[0002]

2. Description of the Related Art Electrophotographic copying machines, printers, facsimiles and the like are provided with a fixing device for fixing a toner image held on a sheet such as a recording medium or a recording material as a recording medium to the sheet. .

There are various types of fixing devices, but a general heat roller type fixing device is a fixing roller that heat-melts toner on a sheet, and a pressure that presses the fixing roller to sandwich the sheet. And a roller. The fixing roller is formed in a hollow cylindrical shape, and a heat source for heating the fixing roller is provided inside thereof. This heat source heats the fixing roller to a predetermined fixing temperature required for fixing by melting the toner by heat.

A tubular heater such as a halogen lamp is generally used as a heat source in the heat roller fixing device. The halogen lamp is arranged on the central axis of the fixing roller, and the fixing roller is heated by the radiant heat of the halogen lamp. . Such a halogen lamp heating type fixing device is
Although it is low in cost, it has the drawback of low thermal efficiency and large energy loss because it is heated by radiant heat.

In order to solve these drawbacks and meet the recent demand for energy saving, an induction heating type fixing device has been proposed.

For example, Japanese Patent Publication No. 4-73155 discloses that
There is described an induction heating fixing device in which a coil formed by spirally winding a winding, which penetrates a core forming a closed magnetic path, is concentrically arranged inside the fixing roller inside a conductive fixing roller. In this fixing device, a coil is energized to generate a magnetic flux in the core, and an induced current is induced in the fixing roller by the magnetic flux to heat the fixing roller by Joule heat.

A fixing device using such induction heating is
Since the heating element such as the fixing roller is directly heated by electromagnetic induction, the heat conversion efficiency is higher than that of the halogen lamp heating method, and the fixing roller surface is quickly heated to the fixing temperature with less electric power. It becomes possible to meet the demand for energy saving. In particular, the one having a core forming a closed magnetic circuit as in the above publication has almost no leakage of magnetic flux and can efficiently generate a secondary current in the fixing roller, so that the energy saving effect is high, and a large-sized high-speed copying machine or a high-speed copying machine can operate at high speed. Suitable for printers, etc.

[0008]

In the above publication, the core has a first magnetic member that is inserted into the fixing roller, a second magnetic member that faces the surface of the fixing roller, and both ends of the first and second magnetic members. Part of the first and second magnetic members, which is composed of a total of four elements that can be attached to and detached from each other of the two third magnetic members located in the first part of the third magnetic member.
It is described that by removing the magnetic member, the fixing roller can be easily attached to and detached from the core, and the convenience during maintenance and production is improved.

According to the above construction, the fixing roller can be detachably attached to the core, but since the core is composed of four elements, there are air gaps at four places. Due to this air gap, the magnetic resistance of the entire core increases, which hinders the improvement of the efficiency of generating a secondary current in the fixing roller. Further, since the third magnetic member is separated from the first and second magnetic members when the fixing roller is replaced, the work of assembling the third magnetic member after the completion of the roller replacement is complicated.

The present invention has been made in order to solve the problems associated with the above-mentioned prior art, and while the fixing roller is configured to be detachable from the core, the air gap existing in the core should be minimized. An object of the present invention is to provide an induction heating fixing device capable of reducing the magnetic resistance of the entire core to improve the efficiency of heating the fixing roller.

[0011]

In order to achieve the above object, the induction heating fixing device according to the present invention according to claim 1 is a hollow cylindrical heating rotary member formed of a conductive member, and the heating rotary device. A pressure rotating body that is in pressure contact with the body and holds the recording medium holding the toner between the heating rotating body, and a core that is partially inserted into the hollow portion of the heating rotating body and forms a closed magnetic path; In an induction heating fixing device having a coil wound around the core and arranged in the hollow portion of the heating rotator, for induction heating the heating rotator, the core is:
The first magnetic member made of laminated iron cores, and configured from a relatively openable two elements of the second magnetic member mounted rotatably on said first magnetic member of a multilayer iron core
The heating rotator is detachable by relatively opening the first and second magnetic members. Further, the induction heating fixing according to the present invention according to claim 2
In the device, the first magnetic member has a spring property, and
At the position where the first and second magnetic members are relatively closed,
Note that the second magnetic member is pressed into contact with the second magnetic member. Also,
The induction heating fixing device according to the present invention according to claim 3 is
The first magnetic member is a laminated layer that constitutes the first magnetic member.
The steel plates are alternately stretched and provided with comb-shaped end portions .
The second magnetic member is a laminated steel that composes the second magnetic member.
Comprises an end portion which forms a comb plates extend alternately, said first
And the second magnetic member are relatively closed at the position described above.
It is characterized in that the comb-shaped ends are joined together.
Further, the induction heating fixing device according to the present invention according to claim 4
And the first magnetic member constitutes the first magnetic member.
The laminated steel sheets are alternately stretched and provided with comb-shaped ends.
For example, the second magnetic member constituting the second magnetic member
The laminated steel plates are alternately stretched and provided with comb-shaped ends.
Equipped at the position where the comb-shaped ends are assembled together.
The second magnetic member through the supporting shaft,
Characterized by being rotatably attached to a member
It

By relatively opening the first magnetic member and the second magnetic member, the heating rotor is inserted into and removed from the core. While the heating rotator is detachably attached to the core in this manner, the core is made up of two relatively openable and closable elements, the first and second magnetic members. There are only two gaps. In this way, since the air gap existing in the core is reduced as much as possible, compared with the conventional core structure in which the air gaps exist in four places,
The magnetic resistance of the entire core is reduced, and the efficiency of heating the heating rotor is increased. In addition, since the second magnetic member is not separated from the first magnetic member when the heating rotor is inserted or removed, the work of relatively closing the first and second magnetic members after the replacement of the heating rotor is not complicated.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic structural view showing an induction heating fixing device according to an embodiment of the present invention, and FIG. 2 is a sectional view showing the inside of a fixing roller.

The induction heating fixing device shown in the figure heats and melts the toner 11 held on a sheet 10 as a recording medium to fix it on the sheet 10. The fixing roller is heated by induction heating. (Corresponding) 12, a pressure roller (corresponding to a pressure rotating body) 13 that is in pressure contact with the fixing roller 12, and a coil 1 that induction-heats the fixing roller 12.
4 and. The fixing roller 12 is rotatably driven in the direction of arrow a in FIG. 1, and the pressure roller 13 is driven to rotate as the fixing roller 12 rotates.

The fixing roller 12 is a conductive hollow cylindrical pipe, and is formed of, for example, a carbon steel pipe, a stainless alloy pipe, an aluminum pipe, or the like, and is mechanically sufficient for the pressure contact force from the pressure roller 13. It is formed with a thickness that ensures strength and a heat capacity. Further, in order to facilitate the separation of the sheet 10 on the outer peripheral surface of the roller, a release layer having a good releasability and heat resistance for the toner is formed by coating with a fluororesin. Sliding bearing portions (not shown) are formed at both ends of the fixing roller 12, and are rotatably attached to a frame of a fixing unit (not shown). Further, the fixing roller 12 has a drive gear (not shown) fixed to one end thereof, and is rotationally driven by a drive source (not shown) such as a motor connected to the drive gear.

The pressure roller 13 comprises a shaft core 15 and a silicon rubber layer 16 formed around the shaft core 15. The silicon rubber layer 16 is a sheet 1 from the surface.
0 is a rubber layer having a heat-resistant property as well as having a releasing property that allows easy release. The pressure roller 13 is pressed in the direction toward the fixing roller 12 by a spring material (not shown).

The induction heating fixing device further has a rectangular core 17 forming a closed magnetic path, and a part of the core 17 penetrates the hollow portion 12a in the fixing roller 12. The coil 14 is formed by spirally winding a winding wire 18, is inserted through a core 17, and is arranged concentrically inside the fixing roller 12. The core 17 is a so-called iron core used in a normal transformer or the like, and preferably has a high magnetic permeability such as a silicon steel plate laminated iron core. Also,
As the winding 18 of the coil 14, an ordinary single conductor having a fusion layer and an insulating layer on the surface is used.

In the fixing operation, first, an alternating current of about 50 to 60 Hz is applied to the coil 14 from a power supply circuit (not shown), and the temperature of the fixing roller 12 is adjusted to a temperature suitable for fixing (for example, 150 to 200 ° C.) by induction heating. ) Until heated. Sheet 10 holding unfixed toner 11
1 is conveyed from the front side as shown by an arrow b in FIG. 1 and is fed toward a nip portion 19 which is a contact portion between the fixing roller 12 and the pressure roller 13. The sheet 10 is conveyed while being nipped by the nip portion 19 while being heated by the heated fixing roller 12 and the pressure applied from the pressure roller 13. As a result, the unfixed toner 11 is transferred to the sheet 1.
0 is fixed, and a fixed toner image is formed on the sheet 10. The toner 11 is held on both sides of the sheet 10 that are in contact with the fixing roller 12. Nip part 1
The sheet 10 that has passed 9 is naturally separated from the fixing roller 12 by the strength of the sheet itself, and is conveyed to the back side in FIG. The sheet 10 is conveyed by a paper discharge roller (not shown) and is discharged onto a paper discharge tray.

Particularly, in the present embodiment, the core 17 is
Has a first magnetic member 21 made of a laminated iron core and a second magnetic member 22 made of a laminated iron core and rotatably attached to the first magnetic member 21, and includes a first magnetic member 21 and a second magnetic member 22. The fixing roller 12 is configured to be detachable by relatively opening the magnetic members 21 and 22.

More specifically, the first magnetic member 21 is
An insertion portion 23 that penetrates the inside of the fixing roller 12, a return portion 24 that faces the surface of the fixing roller 12, and an insertion portion 23.
And a return portion 24 and a connecting portion 25 that connects the return portion 24 on the left side in the figure, and these are integrally formed. The right sides of the insertion portion 23 and the return portion 24 are opened, and the second magnetic member 22 is arranged in this opened portion. As shown in FIG. 3, the laminated steel plates are alternately extended to form a gap between the lower end of the second magnetic member 22, the right end of the insertion part 23, the upper end of the second magnetic member 22, and the right end of the return part 24. Part 26
It is a comb-shaped extending piece 27 that forms the. And
The extending pieces 27 in the insertion portion 23 of the first magnetic member 21 and the extending pieces 27 in the lower end portion of the second magnetic member 22 are alternately assembled, and the support shaft 28 is inserted and fixed in the extending piece 27, whereby the second magnetism is obtained. The member 22 is rotatably attached to the first magnetic member 21. These first and second
The magnetic members 21 and 22 are formed by punching a stack of steel plates by press working or the like. The position of the second magnetic member 22 shown by the solid line in FIG. 1 is called the closed position, and the position shown by the phantom line is called the open position.

Since the insertion portion 23 and the return portion 24 of the first magnetic member 21 are relatively long and the right side thereof is open, the first magnetic member 21 has a spring property, so that the working The person can separate the right end of the return portion 24 from the insertion portion 23. In this way, with the return portion 24 of the first magnetic member 21 being separated from the insertion portion 23, the rotation of the second magnetic member 22 between the closed position and the open position is performed. With this configuration, the upper end portion of the second magnetic member 22 does not contact the return portion 24 of the first magnetic member 21, and the second magnetic member 22 can be easily rotated. Further, when the return portion 24 is returned after the second magnetic member 22 is rotated to the closed position, the return portion 24 of the first magnetic member 21 causes the return portion 24 of the second magnetic member 22 to move due to the elasticity of the first magnetic member 21. It will be pressed against the upper end surface. In addition,
It is preferable that the upper end portion of the second magnetic member 22 and the right end portion of the return portion 24 also have a comb shape.

The basic operating principle of the induction heating fixing device constructed as described above is similar to that of the transformer, and the coil 1
Reference numeral 4 corresponds to the input side primary coil (N winding), and the fixing roller 12 corresponds to the output side secondary coil (1 winding). Then, the primary coil (coil 14) has 50 to 60
When an AC voltage V1 of about Hz is applied, a current I1 flows through the primary coil. The magnetic flux φ generated thereby flows through the core 17 forming the closed magnetic path, and the magnetic flux φ generates an induced electromotive force V2 in the secondary coil (fixing roller 12), which causes a current I2 along the circumferential direction of the fixing roller 12. Flows. Since a closed magnetic circuit is formed by the core 17, there is no leakage magnetic flux in principle, and the primary side energy V1 × I1 and the secondary side energy V2 × I2 are substantially equal.

In the part where heat is generated in the system in which the induction heating is performed, the first is heat generation of the coil due to copper loss in the copper wire of the primary coil, that is, the heat of the coil 14, and the second is
Heat generation of the coil due to copper loss in the copper wire of the secondary coil, that is, heat generation of the fixing roller 12, and third heat generation of the core 17 due to Joule heat loss and hysteresis loss generated inside the core. In the induction heating fixing device, the above-mentioned first and third heat generation causes energy loss, so that these heat generations are suppressed as much as possible, while the second copper loss is used to heat the fixing roller 12. Is.

By the way, since the releasing layer of the fixing roller 12 has a life, it may be necessary to replace the fixing roller 12 with a new fixing roller 12 at the time of maintenance.

When the fixing roller 12 is replaced in this way, first, the second magnetic member 22 is rotated clockwise from the closed position to the open position about the support shaft 28 in the drawing. The second magnetic member 22 rotated to the open position is the first magnetic member 21.
It forms a linear shape together with the insertion portion 23 of. In this state, the first
The existing fixing roller 12 is moved to the right side in the drawing from the insertion portion 23 of the magnetic member 21 and pulled out. Then, the hollow portion 12a of the new fixing roller 12 is moved to the second magnetic member 22 in the open position.
To the predetermined position of the insertion portion 23. Then, the second magnetic member 22 is moved from the open position to the closed position by the support shaft 28.
When the fixing roller 12 is rotated in the counterclockwise direction in the drawing, the replacement work of the fixing roller 12 is completed.

Similarly, at the time of production, the fixing roller 12 is rotated with the second magnetic member 22 rotated to the open position.
Is inserted to a predetermined position of the insertion portion 23 of the first magnetic member 21.

In the present embodiment, by fixing the first magnetic member 21 and the second magnetic member 22 relative to each other, the fixing roller 1
2 is inserted into and removed from the core 17. As described above, the fixing roller 12 is detachably attached to the core 17, but the core 17 is made up of the two elements of the first and second magnetic members 21 and 22. The gap is defined by the insertion portion 23 of the first magnetic member 21 and the second magnetic member 22.
Air gap A1 between the lower end of the first magnetic member 2 and the first magnetic member 2
There are only two places, that is, the air gap A2 between the first return portion 24 and the upper end portion of the second magnetic member 22. Since the air gap existing in the core 17 is reduced as much as possible in this manner, the magnetic resistance of the entire core 17 is reduced as compared with the conventional core structure in which the air gaps exist in four places. As a result, the iron loss of the core 17 can be reduced and the efficiency of heating the fixing roller 12 can be increased, and the energy saving effect can be further enhanced.

Further, since the second magnetic member 22 is not separated from the first magnetic member 21 when the fixing roller 12 is inserted or removed, the first and second magnetic members 21 and 2 are completed after the roller replacement is completed.
The work of relatively closing 2 becomes extremely simple. further,
Since the core 17 is composed of two elements, it is possible to reduce the processing cost by reducing the number of parts.

In order to make the fixing roller 12 detachable, in the entire area of the core 17 forming the closed magnetic path, the areas corresponding to the range in which the fixing roller 12 moves at the time of attachment / detachment are the first and the first areas. It suffices to form a straight line within the inner diameter of the fixing roller 12 when the second magnetic members 21 and 22 are relatively opened. Therefore, the first and second magnetic members 2
The specific configuration of the core 17 composed of 1 and 22 is not limited to the illustrated example. For example, as conceptually shown in FIG. 4A, even if the return portion 24a of the first magnetic member 21a and the upper end portion of the second magnetic member 22a are rotatably connected via a support shaft 28a, This core 17a has the same effect. Further, the core 17b shown in FIG.
At the lower end of the second magnetic member 22a shown in FIG. 3, an entry portion 22b having a length that does not come into contact with the inner peripheral surface of the fixing roller 12 during rotation and is provided along the axis of the fixing roller 12 is provided. In the core 17c shown in FIG. 6C, the first and second magnetic members 21c and 22c are formed in symmetrical L-shapes, and the support shaft 28 is provided at a position away from the axis of the fixing roller 12.
c is provided. Further, the core 1 shown in FIG.
7d, the first magnetic member 21d is formed in a linear shape, the second magnetic member 22d is formed in a cup shape, and the support shaft 28d is provided at a position on the axis of the fixing roller 12.

[0031]

As described above, according to the present invention, the heating rotary member is configured to be attachable to and detachable from the core, while the core is composed of the first and second magnetic members which are relatively openable and closable. Since it is composed of individual elements, the air gap existing in the core can be reduced as much as possible, and the magnetic resistance of the entire core can be reduced. As a result, the efficiency of heating the heating rotator can be increased, and the energy saving effect can be further enhanced.

Further, when the heating rotary member is inserted or removed, the second
Since the magnetic member is not separated from the first magnetic member, the work of relatively closing the first and second magnetic members after the replacement of the heating rotor is simplified.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an induction heating fixing device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the inside of a fixing roller.

FIG. 3 is an enlarged view showing a main part of a core.

4 (A) to 4 (D) are conceptual diagrams showing modified examples of the configuration of the core composed of the first and second magnetic members.

[Explanation of symbols]

10 ... Sheet (recording medium) 11 ... Toner 12 ... Fixing roller (heating rotator) 12a ... Hollow part 13 ... Pressure roller (pressure rotating body) 14 ... Coil 17 ... Core 21 ... First magnetic member 22 ... Second magnetic member 28 ... Spindle A1, A2 ... Air gap

Claims (4)

(57) [Claims] 1. A hollow cylindrical heating rotator formed of a conductive member, and a pressure rotator which is in pressure contact with the heating rotator and holds a recording medium holding toner between the heating rotator. A core part of which is inserted into a hollow part of the heating rotor to form a closed magnetic circuit; and a core wound around the core and disposed in the hollow part of the heating rotor to heat the heating rotor by induction heating. An induction heating fixing device having a coil, and the core is a first magnetic member made of a laminated iron core , and
Beauty, freely relatively opening and closing of the second magnetic member mounted rotatably on said first magnetic member of a multilayer iron core 2
An induction heating fixing device comprising individual elements , wherein the heating rotator is detachable by relatively opening the first and second magnetic members. 2. The first magnetic member has a spring property,
When the first and second magnetic members are relatively closed,
And a pressure contact with the second magnetic member.
The induction heating fixing device according to claim 1. 3. The first magnetic member is the first magnetic member.
The laminated steel plates forming the member are alternately stretched to form a comb shape
An end portion, and the second magnetic member constitutes the second magnetic member.
Laminated steel sheets are alternately stretched and provided with comb-shaped end portions, and the first and second magnetic members are positioned relatively close to each other.
The comb-shaped ends are joined together.
The induction heating fixing device according to claim 1. 4. The first magnetic member is the first magnetic member.
The laminated steel plates forming the member are alternately stretched to form a comb shape
An end portion, and the second magnetic member constitutes the second magnetic member.
Laminated steel sheets are alternately stretched and provided with comb-shaped ends, and a support provided at a position where the comb-shaped ends are assembled.
The second magnetic member is connected to the first magnetic member via an axis.
Claims characterized by being rotatably attached to
The induction heating fixing device according to claim 1 or 3.