JP4320617B2 - Fixing roller and fixing device - Google Patents

Description

  The present invention relates to an electromagnetic induction heating type fixing roller used for, for example, an electrophotographic apparatus such as a copying machine, a laser printer, a facsimile machine, etc., for melting and fixing (heating fixing) an unfixed image on a recording material, and this fixing The present invention relates to a fixing device using a roller.

  In recent fixing devices, in order to save energy, it is considered to employ an induction heating type heat source capable of obtaining high heat conversion efficiency. In particular, a structure in which a magnetic flux generated by a coil is guided to a conductive heat generation layer of a fixing roller of a fixing device by a core material such as a ferrite core has attracted attention because of its compactness and high efficiency.

  The conventional electromagnetic induction heating type fixing device includes a fixing roller, a pressure roller that is in contact with the fixing roller to form a nip, and a magnetic flux generating means that is disposed outside the fixing roller and generates a magnetic flux. And.

  The fixing roller includes a sponge layer and an electromagnetic induction heat generating layer in order from the inner side to the outer side in the radial direction, and heats the electromagnetic induction heat generating layer of the fixing roller by the magnetic flux of the magnetic flux generating means, thereby The recording material carrying the unfixed image is conveyed while being sandwiched, and the unfixed image is melted and fixed on the recording material (see Japanese Patent Laid-Open No. 2000-214714: Patent Document 1).

  However, in the conventional fixing roller, since the sponge layer and the electromagnetic induction heat generating layer are bonded, the following problems occur with respect to the fixing roller due to stress such as heat and pressure.

  That is, when the adhesive force between the sponge layer and the electromagnetic induction heating layer is small, there is a problem that the sponge layer is damaged due to adhesion peeling between the sponge layer and the electromagnetic induction heating layer. It was.

  On the other hand, when the adhesive force between the sponge layer and the electromagnetic induction heat generating layer is large, when the sponge layer is thermally expanded and deformed, the electromagnetic induction heat generating layer follows and deforms, and the surface of the fixing roller is deformed. There was a problem to do.

In short, in the conventional fixing roller, since the sponge layer and the electromagnetic induction heat generating layer are bonded, the durability is inferior and the cost of the adhesive is required.
JP 2000-214714 A

  Accordingly, an object of the present invention is to provide a fixing roller capable of improving durability and reducing manufacturing cost.

In order to solve the above problems, the fixing roller of the present invention is:
An outer roller having an electromagnetic induction heating layer;
An inner roller that is inserted without being bonded to the inside of the outer roller and has a sponge layer,
The outer diameter radius R [mm] of the inner roller and the inner diameter radius r [mm] of the outer roller are:
r−0.5 <R <r + 0.5
Meet the,
The outer roller has an elastic layer and a release layer disposed in order on the outer side of the electromagnetic induction heating layer,
The inner roller includes a support layer disposed inside the sponge layer, and a protective layer disposed outside the sponge layer and reducing frictional force between the inner surface of the electromagnetic induction heat generating layer. It is said.

  According to the fixing roller of the present invention, since the inner roller having the sponge layer is inserted without being bonded to the inner side of the outer roller having the electromagnetic induction heat generating layer, the sponge layer and the electromagnetic induction heat generating layer are inserted. Are not bonded to each other. As described above, since no adhesive is used between the sponge layer and the electromagnetic induction heating layer, the problem of adhesion peeling between the sponge layer and the electromagnetic induction heating layer is eliminated, and improvement in durability can be expected. At the same time, the cost of the adhesive can be reduced. That is, in the fixing roller of the present invention, the inner roller and the outer roller are not bonded in consideration of improvement in durability and reduction in manufacturing cost.

Further, the outer diameter radius R of the inner roller and the inner diameter radius r of the outer roller satisfy r−0.5 <R <r + 0.5, so that the inner roller can be easily inserted inside the outer roller. Thus, the fixing roller can be easily manufactured, and when the fixing roller is rotated, the outer diameter of the outer roller is stabilized. Therefore, when the fixing roller is heated, the outer circumferential direction of the outer roller is increased. The temperature distribution becomes substantially constant and good, and the image quality of the recording material passing through the fixing roller becomes good. Further, since the protective layer is disposed outside the sponge layer, the durability of the sponge layer is improved. For example, even if the sponge layer expands due to heat, a slip occurs between the protective layer and the electromagnetic induction heat generating layer, thereby reducing stress on the sponge layer.

  In one embodiment, the fixing roller includes a regulating member that sandwiches the outer roller from both axial ends of the outer roller and restricts the axial movement of the outer roller.

  According to the fixing roller of this embodiment, since the restriction member is provided, when the fixing roller is rotated, the outer roller is prevented from moving in the axial direction (meandering) and passes through the fixing roller. The image quality of the recording material to be recorded is further improved.

In the fixing device of the present invention,
The fixing roller;
A pressure roller for nipping and conveying the recording material together with the fixing roller;
Magnetic flux generating means is provided outside the fixing roller and generates magnetic flux to generate heat in the electromagnetic induction heat generating layer of the fixing roller.

  According to the fixing device of the present invention, since the fixing roller is provided, less maintenance and inspection are required due to the durability, manufacturing workability, and outer diameter stability of the fixing roller. The image quality can be improved.

  Further, the fixing device according to an embodiment includes a driving unit that rotates the pressure roller.

  According to the fixing device of this embodiment, since the pressure roller is rotated by the driving unit, the rotation of the pressure roller can be accurately controlled and the recording material can be accurately conveyed.

  According to the fixing roller of the present invention, since the inner roller and the outer roller are not bonded, it is possible to improve durability and reduce manufacturing cost. Further, since the outer diameter radius R of the inner roller and the inner diameter radius r of the outer roller satisfy r−0.5 <R <r + 0.5, the inner roller can be easily inserted inside the outer roller. At the same time, the outer diameter of the outer roller is stabilized.

  Further, according to the fixing device of the present invention, since the fixing roller is provided, maintenance and inspection can be reduced and the image quality of the recording material can be improved.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First embodiment)
FIG. 1 is a cross-sectional configuration diagram showing an embodiment of a fixing device according to the present invention. As shown in FIG. 1, the fixing device is of an induction heating type, and includes an electromagnetic induction heating type fixing roller 1, a pressure roller 2 that contacts the fixing roller 1 to form a nip N, and the fixing roller. 1 is provided on the outer side of the magnetic flux generating means 3 for generating magnetic flux.

  Then, after the fixing roller 1 is heated by the magnetic flux of the magnetic flux generating means 3, the recording material P carrying the unfixed image t is passed between the fixing roller 1 and the pressure roller 2, and the nip While the recording material P is nipped and conveyed by N, the unfixed image t is melt-fixed (heat-fixed) on the recording material P.

  This fixing device constitutes an image forming apparatus such as a copying machine, a laser printer, or a facsimile together with an image forming means (not shown) for forming the unfixed image t on the recording material P.

  The recording material P is, for example, a recording material such as paper or an OHP sheet, and the unfixed image t is a heat-meltable toner made of, for example, a resin, a magnetic material, or a colorant.

  The fixing roller 1 and the pressure roller 2 are arranged to face each other in parallel, and both end sides thereof are rotatably supported by a bearing member (not shown). The fixing roller 1 is urged toward the shaft side of the pressure roller 2 by a pressure mechanism such as a spring (not shown), and is pressed against the outer surface of the pressure roller 2 with a predetermined pressure to form the nip N. .

  The pressure roller 2 is rotationally driven at a predetermined peripheral speed in a clockwise direction indicated by an arrow by a driving means 9 such as a motor. The fixing roller 1 rotates following the rotation of the pressure roller 2 by the frictional force of contact with the pressure roller 2 at the nip N.

  As shown in FIGS. 1 and 2, the fixing roller 1 includes an outer roller 15 and an inner roller 10 inserted without being bonded to the inner side of the outer roller 15.

  The inner roller 10 includes a support layer 11, a sponge layer 12, and a protective layer 13 that are sequentially arranged from the inner side to the outer side in the radial direction. The outer roller 15 has an electromagnetic induction heat generating layer 16, an elastic layer 17, and a release layer 18 that are arranged in order from the inner side to the outer side in the radial direction.

  For the support layer 11, for example, an aluminum cored bar cylinder having an outer diameter of 40 mm and a thickness of 3 mm is used. The support layer 11 may be a heat-resistant molded pipe such as iron or PPS (polyphenylene sulfide), for example, as long as the strength of the material can be secured. However, the core metal generates heat. In order to prevent this, it is desirable to use a nonmagnetic material that is less affected by electromagnetic induction heating.

  The sponge layer 12 is for insulating and maintaining the heat generated in the electromagnetic induction heat generating layer 16, and a sponge material (heat insulation structure) made of rubber material or resin material having heat resistance and elasticity is used. As described above, by using a sponge body (heat insulating structure) of heat-resistant and elastic rubber material or resin material for the sponge layer 12, the electromagnetic induction heat generating layer 16 can be reliably insulated and retained. The width of the nip N is increased by allowing the induction heating layer 16 to bend, and the roller hardness of the fixing roller 1 is made smaller than that of the pressure roller 2 to improve paper discharge performance and recording material separation performance. can do. For example, when a silicon sponge material is used for the sponge layer 12, the thickness is 2 to 10 mm, preferably 3 to 7 mm, and the hardness is set to 20 to 60 degrees, preferably 30 to 50 degrees with an Asker rubber hardness meter. Is done.

  The protective layer 13 is for reducing the frictional force with the inner surface of the electromagnetic induction heat generating layer 16 and suppressing the axial movement (meandering force) of the outer roller 15. For example, PFA, PTFE, FEP Fluorine resin such as PFEP is preferably used. 5-100 micrometers is preferable and, as for the thickness of this protective layer 13, 10-50 micrometers is more preferable.

  The electromagnetic induction heat generating layer 16 is, for example, an endless nickel electroformed belt layer having a thickness of 10 to 100 μm, desirably 20 to 50 μm. In addition, as another material of the electromagnetic induction heat generating layer 16, a material having a relatively high magnetic permeability μ and an appropriate resistivity ρ such as a magnetic material (magnetic metal) such as magnetic stainless steel may be used. . Moreover, even if it is a nonmagnetic material, electroconductive materials, such as a metal, can be used by making a material into a thin film, for example. The electromagnetic induction heat generating layer 16 may be made of a resin in which heat generation particles are dispersed. By using a resin-based material for the electromagnetic induction heat generating layer 16, the separation property of the recording material P can be improved. Can be better.

  In the electromagnetic induction heat generating layer 16, an eddy current is generated by the magnetic flux of the magnetic flux generating means 3, and heat is generated by Joule heat, and the fixing roller 1 is heated by this heat generation. This heating is called electromagnetic induction heating.

  The elastic layer 17 is made of a heat-resistant and elastic rubber material or resin material, and improves the adhesion between the recording material P and the surface of the fixing roller 1. As the elastic layer 17, for example, a heat-resistant elastomer such as silicon rubber or fluorine rubber that can withstand use at a fixing temperature is used. Various fillers may be mixed in the elastic layer 17 for the purpose of thermal conductivity, reinforcement, and the like. Examples of the thermally conductive particles include diamond, silver, copper, aluminum, marble, and glass. Examples include silica, alumina, magnesium oxide, boron nitride, and beryllium oxide.

  The thickness of the elastic layer 17 is, for example, preferably 10 to 800 μm, and more preferably 100 to 300 μm. When the thickness of the elastic layer 17 is less than 10 μm, it becomes difficult to obtain elasticity in the thickness direction. On the other hand, when the thickness of the elastic layer 17 exceeds 800 μm, the heat generated in the electromagnetic induction heating layer 16 is It becomes difficult to reach the outer peripheral surface of the fixing roller 1, and the thermal efficiency tends to deteriorate.

  The hardness of the elastic layer 17 is preferably 1 to 80 degrees, more preferably 5 to 30 degrees in terms of JIS hardness, and while preventing a decrease in strength and poor adhesion in the elastic layer 17, an unfixed image (toner) It is possible to prevent the fixing problem of t. In this case, the elastic layer 17 is preferably made of silicon rubber. Specifically, the silicon rubber is a one-component, two-component or three-component or more silicone rubber, LTV type, RTV type. Alternatively, HTV type silicon rubber, condensation type or addition type silicon rubber can be used. In this embodiment, the elastic layer 17 is silicon rubber having a JIS hardness of 10 degrees and a thickness of 200 μm.

  The release layer 18 enhances the releasability of the surface of the fixing roller 1, and can withstand use at a fixing temperature and has toner releasability. As the release layer 18, for example, silicon rubber, fluororubber, or fluororesin such as PFA, PTFE, FEP, PFEP, or the like is used. 5-100 micrometers is preferable and, as for the thickness of the said mold release layer 18, 10-50 micrometers is more preferable. In the release layer 18, a conductive material, an abrasion resistant material, or a good heat conductive material may be added as a filler. Further, in order to improve the interlayer adhesion, an adhesion treatment with a primer or the like may be performed.

  According to the fixing roller 1 having the above-described configuration, the inner roller 10 and the outer roller 15 are not bonded to each other. Therefore, the problem of adhesion peeling between the conventional sponge layer and the electromagnetic induction heat generating layer is prevented, and a long service life is achieved. Can be achieved. Further, the adhesive between the inner roller 10 and the outer roller 15 can be omitted, and the cost of the adhesive can be reduced at the same time.

Further, the outer diameter radius R [mm] of the inner roller 10 and the inner diameter radius r [mm] of the outer roller 15 satisfy the following (Formula 1).
r−0.5 <R <r + 0.5 (Formula 1)

  Thus, since the fixing roller 1 satisfies the above (Formula 1), the inner roller 10 can be easily inserted inside the outer roller 15, and the manufacturing of the fixing roller 1 is facilitated. Further, since the outer diameter of the outer roller 15 is stabilized when the fixing roller 1 is rotated, the temperature distribution in the circumferential direction of the outer roller 15 is substantially constant and good when the fixing roller 1 is heated. Thus, the image quality of the recording material P is improved.

  That is, when the upper limit value is exceeded (R> r + 0.5), it becomes difficult to insert the inner roller 10 inside the outer roller 15, and it becomes difficult to manufacture the fixing roller 1. Specifically, FIG. 3 shows a correspondence diagram between the value of (R−r) and the evaluation of workability of inserting the inner roller into the outer roller. As can be seen from FIG. 3, when the value of (R−r) is 0.6 mm or less, the work of fitting the inner roller into the outer roller becomes worse. Further, when the value of (R−r) is 0.5 mm or more, the inner roller can be fitted into the outer roller. Further, when the value of (R−r) is 0.3 mm or more, the work of fitting the inner roller into the outer roller becomes good. Thus, the inner roller 10 can be easily fitted inside the outer roller 15 when R <r + 0.5, preferably R <r + 0.3. Here, since the inner roller 10 has the sponge layer 12, even if the outer diameter radius R of the inner roller 10 is set slightly larger than the inner diameter radius r of the outer roller 15, workability is impaired. There is nothing.

  On the other hand, if it is less than the lower limit (R <r−0.5), the outer diameter of the outer roller 15 is not stable when the fixing roller 1 is rotated. The temperature distribution in the circumferential direction of the outer roller 15 does not become substantially constant and the image quality of the recording material P becomes poor. More specifically, FIG. 4 is a graph showing the relationship between the value of (r−R) and the GAP fluctuation between the fixing roller (outer peripheral surface) and the magnetic flux generation means (bobbin). FIG. 2 is a graph showing the relationship between the distance between the fixing roller (outer peripheral surface) and the magnetic flux generation means (bobbin) and the temperature increase rate of the fixing roller (heating performance of the fixing roller). As can be seen from FIGS. 4 and 5, it is desirable that r−R <0.5 in order to make the fluctuation with respect to the GAP fluctuation of the fixing roller heating performance within 3%. As described above, if the fluctuation of the fixing roller heating performance can be reduced to about 3% or less, the fluctuation of the temperature distribution in the circumferential direction of the fixing roller can be set to a level at which there is no problem in image quality.

  As shown in FIG. 1, the pressure roller 2 includes a support layer 21, a sponge layer 22, and a release layer 23 that are arranged in order from the inner side to the outer side in the radial direction. The support layer 21, the sponge layer 22 and the release layer 23 of the pressure roller 2 are the same as the support layer 11, the sponge layer 12 and the release layer 18 of the fixing roller 1, respectively.

  For example, the support layer 21 is an aluminum cored bar having an outer diameter of 20 mm and a thickness of 3 mm. The sponge layer 22 is a silicon sponge rubber having a thickness of 7 mm. The release layer 23 is a fluorine-based resin such as PTFE or PFA having a thickness of 10 to 50 μm.

  As long as the material of the support layer 21 can secure the strength, for example, a pipe of a heat-resistant mold such as iron or PPS (polyphenylene sulfide) can be used, but in order to prevent the cored bar from generating heat. It is desirable to use a nonmagnetic material that is less affected by electromagnetic induction heating. In addition, as the sponge layer 22, solid rubber may be used in place of silicon sponge rubber to further improve the releasability.

  The pressure roller 2 is pressed against the fixing roller 1 with a load of 300 to 500 N. In this case, the width dimension of the nip N (the dimension in the conveyance direction of the recording material P) is about 5 to 10 mm. Of course, the width of the nip N may be changed by changing the load.

  As shown in FIG. 6, the fixing roller 1 includes a pair of regulating members 40 that regulate the axial movement of the outer roller 15 by sandwiching the outer roller 15 from both axial ends of the outer roller 15. 40. More specifically, the regulating member 40 has a donut shape, and the inner surface of the regulating member 40 is fitted and fixed to the shaft portion 41 a of the core member 41 constituting the support layer 11.

  The axial length of the nip forming surface (the outer roller 15) of the fixing roller 1 is set longer than the axial length of the nip forming surface (the release layer 23) of the pressure roller 2. Yes.

  Thus, since the fixing roller 1 includes the regulating members 40, 40, when the fixing roller 1 is rotated following the rotation of the pressure roller 2, the inner roller 10 and the outer roller 10 are rotated. Even if the roller 15 is not bonded, the outer roller 15 is prevented from moving in an axial direction (meandering) by the restriction members 40 and 40. Therefore, generation of wrinkles or the like on the recording material P is prevented, and the image quality of the recording material P is further improved.

  Further, since the regulating member 40 is fixed to the core member 41, the regulating member 40 rotates together with the inner roller 10 and the outer roller 15, so that the axial end portion of the outer roller 15 is rotated. The stress applied to the outer roller 15 can be reduced, and the axial end of the outer roller 15 can be prevented from being damaged.

  As shown in FIG. 1, the magnetic flux generation means 3 includes an exciting coil 31 and a magnetic core 32, and is opposed to the fixing roller 1 on the outside of the fixing roller 1. It is arranged along.

  The magnetic core 32 includes a coil bobbin 33 formed in a cup shape (trapezoidal shape) whose cross section is a downward opening, and a cover member 34 that covers the coil bobbin 33 with a predetermined gap. The magnetic core 32 is a long member having a length dimension substantially corresponding to the axial dimension of the fixing roller 1, and covers substantially half of the cross section of the fixing roller 1 inside the coil bobbin 33. .

  The magnetic core 32 has a protruding portion 32a that protrudes toward the fixing roller 1 at the center, and enhances the heat generation efficiency of the fixing roller 1. As the magnetic core 32, one having a high magnetic permeability and low loss is used. For example, when an alloy such as permalloy is used, the eddy current loss inside the magnetic core 32 increases at a high frequency. It may be structured.

  The magnetic core 32 is used for improving the efficiency of the magnetic circuit and for magnetic shielding. The magnetic circuit portions of the excitation coil 31 and the magnetic core 32 may omit the protrusion 32a if there is a means capable of sufficient magnetic shielding. Further, when a resin material in which magnetic powder is dispersed is used, the magnetic permeability is relatively low, but the shape can be freely set.

  The exciting coil 31 is present in the gap between the coil bobbin 33 and the cover member 34, and has a structure in which a conducting wire is wound in the longitudinal direction along the long coil bobbin 33. It becomes a trapezoid shape.

  The exciting coil 31 is connected to the high frequency converter 4 and supplied with high frequency power of 100 to 2000 [W]. For this reason, the exciting coil 31 is a litz wire formed by bundling several tens to several hundreds of thin wires, and is coated with a heat resistant resin in consideration of the case where heat is transferred to the winding. Use what you did.

  An AC current of 10 to 100 [kHz] is applied to the excitation coil 31 by the high frequency converter 4. The magnetic flux induced by the alternating current passes through the inside of the magnetic core 32 without leaking to the outside, leaks to the outside of the magnetic core 32 for the first time at the protruding portion 32a of the magnetic core 32, and fixes the fixing. An eddy current flows through the electromagnetic induction heat generating layer 16 of the roller 1 and flows through the electromagnetic induction heat generating layer 16, and the electromagnetic induction heat generating layer 16 itself generates Joule heat. The fixing roller 1 is heated by the heat generated by the electromagnetic induction heat generating layer 16.

  A temperature sensor 6 is disposed so as to contact the surface of the fixing roller 1. The temperature sensor 6 is a thermistor, for example, and detects the surface temperature of the fixing roller 1.

  A control circuit 5 is connected to the temperature sensor 6, and the control circuit 5 controls the heating and temperature control of the fixing roller 1 based on the surface temperature detection signal of the fixing roller 1 input from the temperature sensor 6. Control. Specifically, the control circuit 5 controls the high-frequency converter 4 based on a signal from the temperature sensor 6, and increases or decreases the power supply to the exciting coil 31 by the high-frequency converter 4. The surface temperature of the fixing roller 1 is automatically controlled so as to become a predetermined constant temperature.

  Next, the operation of this fixing device will be described. The pressure roller 2 is driven to rotate, and accordingly, the fixing roller 1 is driven to rotate. Further, the electromagnetic induction heat generating layer 16 of the fixing roller 1 generates electromagnetic induction heat by the action of the magnetic flux generated by the magnetic flux generating means 3, and the surface temperature of the fixing roller 1 becomes a predetermined constant temperature. Automatically controlled. The recording material (paper) P carrying the unfixed (toner) image t conveyed from an image forming means (not shown) is introduced into the nip N between the fixing roller 1 and the pressure roller 2. The In this case, the side of the recording material P on which the unfixed image t is formed faces the fixing roller 1.

  The recording material P introduced into the nip N is nipped and conveyed in the nip N and heated by the fixing roller 1, so that the unfixed image t is melted and fixed on the recording material P.

  The recording material P that has passed through the nip N is separated from the fixing roller 1 and discharged and conveyed. A separation claw 8 is disposed so as to contact the surface of the fixing roller 1. The separation claw 8 forcibly separates the recording material P from the surface of the fixing roller 1 when the recording material P sticks to the surface of the fixing roller 1 after passing through the nip N. To prevent paper jams (jams).

  At this time, in the fixing roller 1, the heat capacity of the electromagnetic induction heat generating layer 16 that contributes to heat generation and generates eddy current is small, and the electromagnetic induction heat generating layer 16 is thermally insulated by the sponge layer 12. In order to hold | maintain, it acts so that the said elastic layer 17 and the said release layer 18 may be heated rapidly. For this reason, the surface of the fixing roller 1 quickly reaches the temperature necessary for fixing, and even if the recording material P is deprived of heat, the supply of heat catches up.

  Further, by utilizing the flexibility of the electromagnetic induction exothermic layer 16 itself that is heat-insulated by the sponge layer 12, the elastic property against the formation of the nip N between the fixing roller 1 and the pressure roller 2. Even when the layer 17 is made as thin as 200 μm, a nip N having a width larger than before can be formed, and there is no generation of micro-gloss. Secure separation performance.

  In addition, since the protective layer 13 is disposed outside the sponge layer 12, for example, even if the sponge layer 12 expands due to heat, the protective layer 13 slips between the protective layer 12 and the electromagnetic induction heating layer 13. As a result, stress on the sponge layer 12 is reduced, and the durability of the sponge layer 12 is improved.

  According to the fixing device having the above-described configuration, since the fixing roller 1 is provided, the maintenance and inspection of the fixing roller 1 can be reduced as the durability, manufacturing workability, and outer diameter stability of the fixing roller 1 are improved. The image quality of the material P can be improved. Further, since the pressure roller 2 is rotated by the driving means 9, the rotation of the pressure roller 2 can be accurately controlled, and between the inner roller 10 and the outer roller 15 in the fixing roller 1. Even if slippage occurs, the recording material P can be accurately conveyed.

  In addition, this invention is not limited to the above-mentioned embodiment. For example, the fixing roller 1 includes the support layer 11, the sponge layer 12, the protective layer 13, the electromagnetic induction heat generating layer 16, the elastic layer 17, and the release layer 18. Of course, it is possible to provide a layer of the above.

1 is a cross-sectional configuration diagram illustrating an embodiment of a fixing device of the present invention. FIG. 3 is an enlarged cross-sectional view of a main part showing a developed state of the fixing roller of the present invention. FIG. 6 is a correspondence diagram showing an evaluation of workability of inserting the inner roller into the outer roller with respect to the outer radius R of the inner roller and the inner radius r of the outer roller. It is a graph which shows the GAP fluctuation | variation between a fixing roller and magnetic flux generation means with respect to the outer diameter radius R of an inner side roller, and the inner diameter radius r of an outer side roller. FIG. 6 is a graph showing the temperature increase rate of the fixing roller with respect to the distance between the fixing roller and the magnetic flux generation means. It is sectional drawing of a fixing roller and a pressure roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3 Magnetic flux generating means 9 Driving means 10 Inner roller 11 Support layer 12 Sponge layer 13 Protective layer 15 Outer roller 16 Electromagnetic induction heat generating layer 17 Elastic layer 18 Release layer 40 Restriction member P Recording material t Unfixed Image R Outer radius of inner roller r Inner radius of outer roller

Claims (4)

An outer roller having an electromagnetic induction heating layer;
An inner roller that is inserted without being bonded to the inside of the outer roller and has a sponge layer,
The outer diameter radius R [mm] of the inner roller and the inner diameter radius r [mm] of the outer roller are:
r−0.5 <R <r + 0.5
Meet the,
The outer roller has an elastic layer and a release layer disposed in order on the outer side of the electromagnetic induction heating layer,
The inner roller includes a support layer disposed inside the sponge layer, and a protective layer disposed outside the sponge layer and reducing frictional force between the inner surface of the electromagnetic induction heat generating layer. And fixing roller. The fixing roller according to claim 1,
A fixing roller, comprising: a regulating member that sandwiches the outer roller from both ends in the axial direction of the outer roller and restricts the movement of the outer roller in the axial direction. A fixing roller according to claim 1;
A pressure roller for nipping and conveying the recording material together with the fixing roller;
And a magnetic flux generating means disposed outside the fixing roller and generating magnetic flux to generate heat in the electromagnetic induction heat generating layer of the fixing roller. The fixing device according to claim 3 .
A fixing device comprising drive means for rotating the pressure roller.

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