JP2002367766A - Heating roller and heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating roller and a heating device realizing lowering of thermal capacity, improvement of strength and easiness to manufacture. SOLUTION: A heating roller 40 is provided with a heating layer 44 heated by a heating means and a heat insulation layer 42 bonded on an inner periphery of the heating layer 44 with an adhesive. The thickness of an adhesive layer 43 is to be not less than 10 μm and not more than 100 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating roller and a heating device, and more particularly, to a fixing device in a dry electrophotographic apparatus (such as an image forming apparatus such as a copying machine and a laser printer) and a drying apparatus in a wet electrophotographic apparatus. The present invention relates to a heating roller suitably used in a drying device in an ink jet printer, an erasing device for rewritable media, and the like, and a heating device using the same.

[0002]

2. Description of the Related Art For example, in a fixing device in an image forming apparatus of a dry electrophotographic system, a heating roller, a pressure roller for pressing a recording sheet as a material to be heated, and a heating means for heating the heating roller are provided on the heating roller. The sheet having an unfixed image sent to the fixing device through the developing process passes through a contact nip formed by a heating roller and a pressure roller heated to a predetermined temperature, and during that time, the unfixed sheet on the sheet is unfixed. The image is fixed to the paper by heat and pressure.

In a fixing device using such an electrophotographic process, it is required to reduce the time from power-on or from a standby state to a ready (printable) state, that is, to shorten a rising time and to save energy. Various proposals have been made for this purpose. As one of them, Japanese Patent Application Laid-Open No. Hei 9-244448 proposes a device in which the outer peripheral surface of a heating roller is formed into a drum shape, and the heating roller is made thinner to reduce the heat capacity. Japanese Patent Application Laid-Open No. 8-129313 proposes providing an elastic layer inside a heating roller and providing a thin metal sleeve outside the elastic layer.

[0004]

To reduce the heat capacity of the heating roller in order to shorten the rise time in a heating roller having a predetermined outer diameter, for example, the method disclosed in Japanese Patent Application Laid-Open No. 9-244448 is disclosed. As
It is necessary to make the thickness of the heating roller thinner, but then the second moment of area of the heating roller becomes smaller,
The mechanical strength decreases, and the cross-sectional deformation of the heating roller and the bending, which is the deformation in the longitudinal axis direction, increase. Further, since the thickness of both ends supported by ball bearings and the like is also reduced, the mechanical strength of both ends is reduced, and the cross-sectional deformation of both ends is increased. Therefore, when such a heating roller is used in a fixing device of an electrophotographic image forming apparatus, the bending becomes large, so that stable driving cannot be performed. Problems such as poor fixing occur. In addition, as the cross-sectional deformation at both ends increases, the frictional resistance between the bearing and the like increases, and the required driving torque increases. Further, at the end of the heating roller, an engaging portion such as a notch into which a projection for power transmission formed on the inner peripheral surface of the driving gear is normally formed, but the mechanical strength of the end is low. By the decrease, the shear stress increases, and particularly, the engaging portion is deformed or broken.

Therefore, it is conceivable to provide an elastic layer for improving the strength as disclosed in Japanese Patent Application Laid-Open No. 8-129313. In this case, the displacement between the heating layer and the elastic layer is considered. Fixing means for prevention is required. The fixing means is required not to make the production of the heating roller difficult, not to increase the heat capacity of the heating roller, and the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide a heating roller and a heating device which can solve the above-mentioned problems and can simultaneously realize a reduction in heat capacity, an improvement in strength and ease of manufacture.

[0007]

Means for Solving the Problems and Effects of the Invention A heating roller according to the present invention has a heating layer heated by a heating means and a heat insulating layer joined to the inner periphery of the heating layer by an adhesive. The thickness of the agent layer is in the range of 10 μm or more and 100 μm or less.

As a material for the heating layer, for example, nickel, iron, aluminum, copper, or an alloy thereof is used. The heating layer has a thickness of 10 to 150 μm.

As the heat insulating layer, a sponge material having heat resistance, for example, a sponge made of silicone rubber is used.

As the adhesive, an adhesive having heat resistance, for example, a silicone adhesive is used.

Usually, both ends of the heating roller in the axial direction are supported by bearings such as ball bearings, and a medium to be heated such as recording paper is passed through the intermediate region. A pressure roller for pressing the material to be heated against the heating roller is pressed against the heating roller. At least one of the ends is formed with an engaging portion with the driving gear.

By joining the heat insulating layer to the inner periphery of the heating layer with an adhesive, the strength of the entire heating roller can be improved, thereby making the heating layer thinner and reducing the heat capacity of the entire heating roller. be able to.

Therefore, according to the heating roller of the present invention, it is possible to simultaneously reduce the heat capacity and improve the strength of the heating roller.

The thickness of the adhesive layer is 10 μm or more and 100 μm or more.
It is preferably within the range of m or less. That is, if the thickness of the adhesive layer is less than 10 μm (for example, 5 μm), a sufficient adhesive force cannot be obtained, and the heating layer and the heat insulating layer are displaced during repeated rotations. Is more than 100 μm (for example, 150 μm), the heat generated in the heating layer is used for heating the adhesive, so that the time required for heating the heating roller to a predetermined temperature (warm-up time) becomes longer. By setting the thickness of the adhesive layer within the above range, the gap between the heating layer and the heat insulating layer, which is likely to be caused by repeated rotation, is prevented by the adhesive, and the increase in heat capacity due to the use of the adhesive is suppressed.

As the heating layer, a metal cylinder can be used, and no special processing is required. In addition, bonding with an adhesive can be easily performed as compared with a fixing method such as caulking.

Therefore, according to the heating roller of the present invention, at the same time as reducing the heat capacity and improving the strength of the heating roller,
It is possible to improve the ease of manufacture.

In the heating roller of the present invention, the adhesive layer may be provided over the entire surface of the opposing portion between the heating layer and the heat insulating layer. It may be. That is, for example, the adhesive may be applied at a predetermined interval in the axial direction of the heating roller, or may be applied at a predetermined interval in the circumferential direction of the heating roller.

Since the adhesive is present in a part of the opposing portion between the heating layer and the heat insulating layer, the amount of heat released from the heating layer to the adhesive layer is suppressed, and the warm-up time is reduced. It is possible.

The heating roller according to the present invention has a heating layer heated by a heating means, and a heat insulating layer joined to the inner periphery of the heating layer by an adhesive. It is characterized by being present at both axial ends of the facing portion.

Normally, the intermediate area of the heating roller is a paper passing area through which recording paper or the like is passed, and an adhesive is applied to both ends of the heating roller. The amount of heat released from the layer to the adhesive layer is suppressed, and the warm-up time can be reduced. The thickness of the adhesive layer may be greater than 100 μm.

By bonding the heat insulating layer to the inner periphery of the heating layer with an adhesive, the strength of the entire heating roller can be improved, thereby making the heating layer thinner and reducing the heat capacity of the entire heating roller. be able to.

Therefore, according to the heating roller of the present invention, it is possible to simultaneously reduce the heat capacity and improve the strength of the heating roller.

The gap between the heating layer and the heat insulating layer, which is likely to be caused by repeated rotation, is prevented by the adhesive, and the adhesive is present at both ends of the facing portion between the heating layer and the heat insulating layer. Thereby, the amount of heat that escapes from the heating layer to the adhesive layer can be reduced, and the increase in heat capacity due to the use of the adhesive can be suppressed. The width of the adhesive layer at each end is preferably 5 mm or more (about 10 mm) to prevent displacement.

As the heating layer, a metal cylinder can be used, and no special processing is required. In addition, bonding with an adhesive can be easily performed as compared with a fixing method such as caulking.

Therefore, according to the heating roller of the present invention, at the same time as lowering the heat capacity and improving the strength of the heating roller,
It is possible to improve the ease of manufacture.

In the heating roller of the present invention, the adhesive is
It is preferably applied to the inner periphery of the heating layer. The heat-insulating layer made of silicone rubber or the like of the sponge is more likely to penetrate the adhesive than the heating layer made of iron or the like, so applying the adhesive to the heat-insulating layer requires a larger amount of adhesive. Is applied to the heating layer, the amount of the adhesive can be reduced, and the thickness of the adhesive layer can be easily controlled.

A heating device according to the present invention includes the above-described heating roller, a pressure roller that presses against the heating roller, and a heating unit that externally heats a heating layer of the heating roller.
It is characterized in that the sheet-like material to be heated is heated by pressing and conveying the sheet-like material to be heated by a heating roller and a pressure roller.

By configuring the heating device using the above-described heating roller, a lower heat capacity of the heating roller can be realized as compared with the conventional heating device, the warm-up time can be reduced, and the heating roller can be greatly reduced. Energy saving can be achieved.

As the heating means, a lamp heating method using a halogen lamp or the like, a heater heating method using a ceramic heater, an induction heating method using an induction coil, and the like can be used. It is an induction heating means for generating an induction current by applying an alternating magnetic field to the layer, and it is more preferable that the heating layer of the heating roller is a conductor layer which generates heat in the alternating magnetic field. In order to heat the heating roller uniformly in a short time, it is necessary to arrange the heating means so as to cover the heating roller (about half a circumference). According to the induction heating means, this condition can be easily realized. .

When the heating device is used in the above-described fixing device, the contact nip portion between the heating roller and the pressure roller is pressed against the recording paper having an unfixed toner image formed on both surfaces thereof. In this state, the unfixed toner is melted and fixed on the recording paper.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a fixing device in a dry electrophotographic image forming apparatus will be described below with reference to the drawings.

FIG. 1 shows a main part of the image forming apparatus.

In this image forming apparatus, a recording paper in which four color visible image forming units (10Y), (10M), (10C), and (10B) are materials to be heated.
This is a so-called tandem-type printer arranged along the transport path (P). The visible image forming units are collectively referred to by reference numeral (10). The four visible image forming units (10) are arranged along a recording paper transport device (13) as a recording paper transport means between a paper (P) supply tray (11) and a fixing device (12). Has been established. Then, the image forming apparatus, after multiple transfer of each color toner to the paper (P) conveyed by the conveying device (13) by the visible image forming unit (10), it is fixed by the fixing device (12), Form a full-color image.

More specifically, the transport device (13)
Is a pair of front and rear drive rollers (14) and idle rollers (1
5) and a predetermined peripheral speed (134 m in this example)
m / s), and has an endless transport belt (16) that rotates at a controlled speed. The paper (P) is electrostatically attracted onto the belt (16) and transported from the tray (11) to the fixing device (12). I do. Each visible image forming unit (10) includes a charging roller (1) around a photosensitive drum (17).
8), laser beam irradiation device (19), developing device (20), transfer roller (2
(1) and cleaner (22)
(20) contains yellow (Y), magenta (M), cyan (C), and black (B) toners.

Each visible image forming unit (10) forms a toner image on paper (P) by the following steps. That is, first, the surface of the photoconductor drum (17) is uniformly charged by the charging roller (18), and then the surface of the photoconductor drum (17) is exposed by the laser beam irradiation device (19) according to the image information. Thus, an electrostatic latent image is formed. Thereafter, a toner image was developed with respect to the electrostatic latent image on the photosensitive drum (17) by the developing device (20), and a bias voltage having a polarity opposite to that of the toner was applied to the visualized toner image. The transfer roller (21) sequentially transfers the paper (P) conveyed by the conveyance device (13). Fixing device (12)
A pair of discharge rollers (23) and (24) are provided in front of the transfer belt and between the transport belt (16) and the fixing device (12) and between the fixing device (12) and the discharge rollers (23) and (24). Are provided with paper guides (25) and (26). The paper (P) on which the transfer has been completed is
After being separated from the transport belt (16) by the curvature of (4), it is transported to the fixing device (12) through the guide (25). Fixing device (1
In 2), as will be described in detail later, fixing is performed, and the sheet (P) on which fixing has been completed is discharged by discharge rollers (23) and (24) through a guide (26).

The fixing device (12) in the image forming apparatus described above.
Is shown in FIG.

This fixing device (12) is of an induction heating type, and has a heating roller (fixing roller) (4) as a heating member.
0), an induction coil (49) as a magnetic field generating means, a thermistor (50) as a temperature sensor as a temperature detecting means, an excitation circuit (51) as a temperature controlling means, and a pressure roller as a pressing means (34).

The heating roller (40) is heated by electromagnetic induction to heat the recording paper (P), which is a material to be heated, moving in the fixing device (12). As shown in FIGS. 2 and 3, the heating roller (40) includes a cored bar (41),
A heat insulating layer (42) formed on the outer periphery of the cored bar (41), and a heat insulating layer (42)
An adhesive layer (43) formed on the outer periphery of the heating layer (44) formed on the outer periphery of the adhesive layer (43), and a release layer (45) formed on the outer periphery of the heating layer (44) And

For example, iron, STKM (J
Steel such as IS), non-magnetic stainless steel such as SUS304 (JIS), metals such as aluminum and copper, or alloys thereof are used.

The heat-insulating layer (42) heats the heating layer (44) by the core metal (41).
This is to prevent them from escaping to the side. For the heat insulating layer (42), a sponge material having heat resistance, for example, a sponge made of silicone rubber is suitable.

The adhesive layer (43) comprises a heating layer (44) and a heat insulating layer (42).
This is to prevent the deviation from the position. In this example, the adhesive layer (43) is provided over the entire opposing portion of the heating layer (44) and the heat insulating layer (42). Adhesive layer (43)
Is formed by applying an adhesive in advance on the inner peripheral surface of the heating layer (44). An adhesive having heat resistance, for example, a silicone-based adhesive is suitable for the adhesive.

The heating layer (44) is formed of a conductor to generate heat by receiving a fluctuating magnetic field from the induction coil (49). As the heating layer (44), those having a large relative magnetic permeability are suitable, for example, iron, steel such as STKM (JIS), SU
It is desirable to be made of a magnetic stainless steel such as S430 (JIS), a silicon steel plate, an electromagnetic steel plate, a nickel steel or the like. Further, even if the material has a low relative permeability, for example, SUS3
A material having a large resistivity, such as non-magnetic stainless steel such as 04 (JIS), can be used because it generates a large amount of heat when an eddy current is generated. Alternatively, the heating layer (44) may be configured such that the material having a high relative permeability is disposed on a non-magnetic base member such as ceramics so as to have conductivity.

The release layer (45) is for preventing the toner from offsetting (adhering) from the sheet (P). The release layer (45) includes PFA (copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) or PT
Fluororesins such as FE (polytellorafluoroethylene),
Silicone rubber, fluorine rubber and the like are suitable.

The induction coil (49) is for causing the heating roller (40) to generate heat by eddy current, is formed in a semi-cylindrical shape as a whole, and extends along the outer periphery of about half the circumference on the upper side of the heating roller (40). Are arranged as follows. As described above, when the induction coil (49) is arranged with a curvature along the outer periphery of the heating roller (40), the magnetic flux concentrates on the center side of the induction coil (49), that is, the center side of the heating roller (40), The amount of eddy current generated in the heating roller (40) increases. And the heating layer of the heating roller (40)
When the material of (44) is made of a material having a high magnetic permeability, the magnetic flux is further concentrated, and the heating efficiency is improved.

For the induction coil (49), for example, a single aluminum wire on which a surface insulating layer such as an oxide film is formed is used. However, it may be a copper wire or a copper-based composite member wire, or a litz wire in which an enamel wire is a stranded wire. Whichever wire is used, the total resistance of the coil (49) should be 0.5Ω or less, preferably 0.1Ω or less, in order to suppress the Joule loss in the coil (49).

The induction coil (49) may be arranged only one in the axial direction of the heating roller (40), or the sheet (P) to be fixed
May be arranged depending on the size.

The pressure roller (34) is configured to have a heat-resistant elastic material layer (38) such as silicone rubber on the outer peripheral surface of a core metal (37) made of iron, steel, stainless steel, aluminum or the like. A release layer similar to that of the heating roller (30) may be formed on the surface of the heat-resistant elastic material layer (38) of the pressure roller (34). The pressure roller (34) is pressed against the heating roller (30) by an elastic member such as a spring (not shown) with a force of, for example, 100 N, and thereby has a width of about 3.5 between itself and the heating roller (30).
A contact nip (S) of about mm is formed.

The force applied when the pressure roller (34) is pressed against the heating roller (30) is not limited to the above-mentioned value, but may be an optimum value depending on the configuration of the roller pair and the fixing conditions. Can be set to Also, the width of the contact nip (S) generated by the pressure contact is not limited to the above value, but can be set to an optimal value as appropriate. The width of the contact nip (S) is often set to a value of approximately 2 mm to 7 mm.

As an example of the dimensions of the heating roller (40), the diameter of the core bar (41) is 16 mm, the thickness of the heat insulating layer (42) is 6 mm, the thickness of the adhesive layer (43) is 50 μm, The thickness of the heat generating layer (44) is 40 μm, and the thickness of the release layer (45) is 30 μm.

In the heating roller (40), the adhesive layer
Table 1 shows the results obtained by examining the warm-up time when the thickness of (43) was variously changed, and Table 2 shows the results obtained by examining the durability. In Table 1, WUT
(Second) is a warm-up time when the temperature of the heating roller is increased to 190 ° C. Table 2 shows the presence / absence of adhesion after continuous rotation of the heating roller for 100 hours (○: no problem, x: NG).

[0051]

[Table 1]

[Table 2] From Table 1, when the thickness of the adhesive layer (43) is 100 μm or less,
It can be seen that the warm-up time is not significantly different from the warm-up time when there is no adhesive layer (43), but when the thickness of the adhesive layer (43) is 150 μm, the warm-up time is greatly increased.

From Table 2, it can be seen that the thickness of the adhesive layer (43) is 1
When the thickness is 0 μm or more, good adhesion is exhibited.
When the thickness of (43) is 5 μm, sufficient adhesive strength cannot be obtained, and it can be seen that the heating layer (44) and the heat insulating layer (42) are shifted during repeated rotation.

A second example of the heating roller (40) is shown in FIG.

In the case of the second example, the adhesive layer (43) is a heating layer.
It is formed by applying an adhesive (43a) having a predetermined width to the inner peripheral surface of (44) at predetermined intervals in the axial direction.

A third example of the heating roller (40) is shown in FIG.

In the case of the third example, the adhesive layer (43) is a heating layer.
An adhesive (43b) having a predetermined width is applied to the inner peripheral surface of (44) at predetermined intervals in the circumferential direction.

A fourth example of the heating roller (40) is shown in FIG.

In the case of the fourth example, the adhesive layer (43) is a heating layer.
It is formed by applying an adhesive (43c) only to both ends in the axial direction of the opposing portions of the (44) and the heat insulating layer (42). Then, a portion where the adhesive (43c) is not applied is a sheet passing area for passing a recording sheet as a material to be heated.
In this heating roller (40), the endurance test was performed under the same conditions as in Table 2 with the width of each end of the adhesive layer (43) set to 3 mm and 5 mm. 44) and the heat insulating layer (42) were peeled off, and the peeling was not observed when the width was 5 mm. The width at each end of the adhesive layer (43) is preferably narrow from the viewpoint of securing a paper passing area and not increasing the size of the entire apparatus, and is preferably about 10 mm from the balance with prevention of misalignment.

The operation of the fixing device (12) is as follows.

First, at the time of warm-up, the excitation circuit (51) is turned on, and an alternating current is supplied to the induction coil (49). As a result, the coil (49) is excited, an AC eddy current is induced in the heating layer (44) of the heating roller (40), and heat is generated by Joule heat. The calorific value at this time is, for example, about 1000 W. On the other hand, at the same time as the energization by the excitation circuit (51) is started, the heating roller (40) is rotationally driven by a suitable driving means (not shown), thereby
(34) is driven to rotate. In addition, the surface temperature of the heating roller (40) is constantly detected by the thermistor (50), and the heating roller (4) is detected.
When the surface temperature of (0) reaches a predetermined temperature (190 ° C. in this example), the warm-up is completed, and the energization of the coil (49) by the excitation circuit (51) causes the temperature detection value of the thermistor (50) to be increased. The control is switched to on / off control based on the temperature, and the surface temperature of the heating roller (40) is maintained at a predetermined temperature. Then, in such a state, the recording paper (P) to which the unfixed toner image has been transferred as described above is conveyed to the contact nip portion (S), and is heated by the heating roller (4).
The toner image is melted and fixed by the heat of (0) and the pressure of the pressure roller (34), and is fixed on the sheet (P) to form a robust image.

The temperature control is not limited to the ON / OFF control as described above. For example, phase control, cycle control, etc.
Other schemes can be used.

In the above example, the image forming apparatus is a color image forming apparatus. However, the present invention is not limited to this, and may be applied to a monochrome image forming apparatus for forming a single color toner image.

The heating roller and the heating apparatus according to the present invention are not limited to the fixing apparatus in the dry electrophotographic image forming apparatus as described above, but may be, for example, a drying apparatus in a wet electrophotographic apparatus, a drying apparatus in an ink jet printer, and a rewritable apparatus. The present invention can also be applied to a heating device of a media erasing device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a configuration of a main part of a color laser printer to which the present invention is applied.

FIG. 2 is a configuration diagram illustrating a fixing device in FIG. 1;

FIG. 3 is a longitudinal sectional view showing a first example of a heating roller.

FIG. 4 is a longitudinal sectional view showing a second example of the heating roller.

FIG. 5 is a cross-sectional view illustrating a third example of the heating roller.

FIG. 6 is a longitudinal sectional view showing a fourth example of the heating roller.

[Explanation of symbols]

 (12) Fixing device (34) Pressure roller (40) Heating roller (42) Heat insulation layer (43) Adhesive layer (44) Heating layer (49) Induction coil

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H033 AA30 AA31 BA25 BB12 BB19 BB23 BB26 BE06 3J103 AA02 AA15 AA32 BA04 CA02 CA62 DA05 EA07 FA01 GA02 GA57 GA58 HA03 HA16 3K059 AB28 AD07 AD32 AD40 CD52

Claims (7)

[Claims] 1. A heating layer heated by a heating means, and a heat insulating layer joined to the inner periphery of the heating layer by an adhesive, wherein the thickness of the adhesive layer is in a range of 10 μm or more and 100 μm or less. A heating roller. 2. The heating roller according to claim 1, wherein the adhesive is present in a part of the facing portion between the heating layer and the heat insulating layer. 3. A heating layer which is externally heated by a heating means, and a heat insulating layer joined to the inner periphery of the heating layer by an adhesive, wherein the adhesive is provided at a portion facing the heating layer and the heat insulating layer. A heating roller which is present at both ends in the axial direction. 4. The heating roller according to claim 3, wherein the width of the adhesive layer at each end is 5 mm or more. 5. The heating roller according to claim 1, wherein the adhesive is applied to an inner periphery of the heating layer. 6. The heating roller according to claim 1, further comprising: a pressure roller which is in pressure contact with the heating roller; and heating means for externally heating a heating layer of the heating roller. A heating apparatus for heating a material to be heated by pinching and conveying a sheet-like material to be heated by a pressure roller. 7. An induction heating means for applying an alternating magnetic field to a heating layer of a heating roller to generate an induction current.
7. The heating device according to claim 6, wherein the heating layer of the heating roller is a conductor layer that generates heat in an alternating magnetic field.