JP4469169B2 - Fixing device - Google Patents

Description

  The present invention relates to a fixing device that is mounted on an image forming apparatus such as a copying machine or a printer and fixes a developer image on a sheet.

  An image forming apparatus using digital technology, such as an electronic copying machine, has a fixing device that fixes a developer image melted by heating to a sheet by applying pressure.

  The fixing device includes a heating member that melts a developer, for example, toner, and a pressure member that provides a predetermined pressure to the heating member. A predetermined region is provided in a contact area (nip portion) between the heating member and the pressure member. A contact width (nip width) is formed. On the paper passing through the nip portion, the developer image on the paper melted by the heat from the heating member is fixed by the pressure from the pressure member.

  In a method using a halogen lamp as a heat source for heating a heating member of a fixing device, a pair of rollers is provided on a member to be fixed and toner so as to be able to provide a predetermined pressure, and the halogen lamp is disposed inside at least one of the rollers. The configuration is widely used.

  On the other hand, in the method using induction heating, an example is known in which a heat-resistant film material having a thin metal layer (conductor film) is brought into contact with a member to be fixed in the form of an endless belt or a cylinder (roller).

  In addition, a cylindrical rigid body and a layer made of a low thermal conductivity material are provided on the outside, a conductor layer and a release layer are further arranged on the outside, and the conductor layer is guided by facing the outside of the release layer. In a fixing device using a fixing roller in which an induction superheat source to be heated is disposed, there is an example in which the low thermal conductivity material is silicone rubber or foamed silicone rubber (Patent Document 1).

  In addition, in an image heating apparatus in which a thin conductive layer, a heat insulating layer, and a support layer are brought into close contact with each other from the surface to the inside and heated by excitation from the outside, the surface of the heat insulating layer in contact with the thin conductive layer or the thin conductive layer There is an example in which one or both surfaces in contact with the heat insulating layer are roughened (Patent Document 2).

  On the other hand, there is an example of a heating device that functions as an elastic layer or a conductive heating layer by dispersing conductive and high-permeability particles or whiskers in the elastic layer or surface layer of the conductive heating member (Patent Document 3). ).

Furthermore, there is an example of a heating device that heats a heating rotator including an elastic layer and having a metal sleeve having a thickness of 10 to 150 μm on the outside by a heating means (Patent Document 4).
Japanese Patent Laid-Open No. 2002-49261 (Summary, FIGS. 1 and 2, paragraphs [0016] and [0022]) JP 2001-5315 A (Abstract, Claim 3, FIG. 1 to FIG. 4, Paragraphs [0027] and [0032] to [0036]) JP-A-8-76620 (Abstract, FIG. 1, Claims 1 to 3) JP-A-8-129313 (Abstract, Claim 1, FIG. 2)

  In recent years, in order to reduce power consumption, quick heating can be performed using a heating member in which a thin conductive layer having a small heat capacity is provided outside a layer made of a low thermal conductive material. As the low thermal conductive material, a foam material having a low hardness is used, and a difference in hardness is generated between the conductive layer made of a thin film such as a metal. Due to the difference in hardness, when stress such as pressure, thermal expansion, and thermal contraction is applied from the pressurizing member, there is a risk that the foaming material as the low thermal conductive material will be consumed or foam broken. When the bubble breakage is accelerated and cavities having different sizes are formed, there is a problem that the outer diameter of the conductor layer is not ensured constant in the longitudinal direction of the heating roller.

  In addition, when the conductor layer and the foam material are bonded by applying a heat-resistant adhesive or the like to the entire surface, the foam layer in which the heat of the metal layer is directly conducted is rapidly heated. There is a risk of swelling. Furthermore, the thermal expansion of the foamed layer due to heat generation of the metal layer and the thermal contraction of the foamed layer due to contraction of the volume of air contained in the foamed layer during heat dissipation may be regulated by the metal layer. .

  For this reason, the foamed layer is stretched to the metal layer side, particularly due to thermal contraction, and there is a problem that the foamed layer further breaks down and the life (life) is shortened. In addition, since the metal layer is deformed due to thermal expansion or contraction of the foam layer and the required nip width cannot be secured at the position where the heating member and the pressure member are in contact with each other, a good fixed image cannot be obtained. There is.

  In addition, when the metal layer and the foam layer are not bonded, or when the metal layer is provided as a sleeve (belt), the metal layer meanders with the rotation of the heating roller and may be damaged by being displaced from the foam layer. There is a problem of shortening the life of the metal layer. In addition, in order to support the belt-like metal layer, there is a problem that a complicated mechanism is required, or when the metal belt is driven by pressure from a pressure mechanism, the metal belt is not slid and rotated by an oil roller or the like. There is.

  An object of the present invention is to provide a fixing device that can ensure a nip width of a certain level or more and obtain a good image by preventing a change in hardness in the longitudinal direction of a roller.

The present invention provides a cylindrical metal layer including a first region formed at both ends in the axial direction and a second region formed at the center in the axial direction, and a first larger than the inner diameter of the metal layer . and a foam layer with a central portion disposed inside the unrealized pre Symbol metal layer having an inner diameter and the first outer diameter smaller than the second outer diameter of the end portion of the metal layer having an outer diameter , said end portion of said foam layer is fixed to the first region of the metal layer, the gap between the second region of the metal layer and the central portion of the foam layer is formed Carlo and over La, a heating mechanism for exciting the metal layer provided outside the roller, there is provided a fixing device Ru comprising a.

The present invention also includes a first region formed at both ends in the axial direction and a second region formed at the center in the axial direction, and has a cylindrical shape having a constant inner diameter and outer diameter in the axial direction. and a metal layer, has the outer diameter smaller than the inner diameter of the metal layer, and a foam layer disposed inside the metal layer, has a larger outer diameter than the inner diameter of the metal layer, wherein the metal layer It is fixed to the first region, and the fixing member for positioning the foam layer between the first region mutually the metal layer, the second region of the metal layer by the fixing member and said foamed layer there is provided a roller gap is formed, a heating mechanism for exciting the metal layer provided outside the roller, a fixing device Ru provided with between.

As described above, the fixing device according to the present invention prevents changes in the hardness in the longitudinal direction of the heating roller 1 and prevents the foamed rubber layer 1b supporting the metal conductive layer 1c, which is a thin film, from being consumed or broken. A nip width of a certain level or more can be secured, and a good image can be obtained.
Further, the change in roller hardness due to the expansion of the air inside the foamed rubber due to the temperature change during heating can be eliminated, and the fluctuation of the nip width can be eliminated.
Furthermore, the material to be transferred that passes between the pressure roller is conveyed so as to be pulled to both ends in the axial direction by a heating roller having a foamed rubber layer and / or a metal conductive layer having different outer diameters in the axial direction. And generation of wrinkles can be suppressed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example of a fixing device of the present invention.
As shown in FIG. 1, the fixing device can contact a transfer material, that is, a surface of a paper P on which toner T adheres, a heating member (heating roller) 1 that heats the toner T and the paper P, and a heating roller. And a pressure member (pressure roller) 2 that applies a predetermined pressure to 1.

The heating roller 1 includes a core rod 1a that is a shaft made of a material having rigidity (hardness) that does not deform under a predetermined pressure, and an elastic layer (a foamed rubber layer, a sponge) that is sequentially arranged around the core rod 1a. Layer, silicon rubber layer) 1b and metal member (metal conductive layer) 1c. In the present embodiment, it is preferable to further have a solid rubber layer 1d and a release layer 1e made of a thin film layer such as heat-resistant silicone rubber, for example, outside the metal conductive layer 1c.
The pressure roller 2 has a central axis 2a and preferably has a diameter of 40 mm. The central shaft 2a receives a predetermined pressure from the pressure mechanism 3 that is pressurized by the pressure spring 3a. As a result, the pressure roller 2 is pressed against the heating roller 1, and a constant width (nip width) is formed in the conveyance direction of the paper P at the contact portion (nip portion) of both rollers. The pressure roller 2 is not limited to this, and may be a roller having a metal conductive layer and an elastic layer, like the heating roller 1.
The heating roller 1 that is in contact with the pressure roller 2 while maintaining a certain nip width or more with the pressure from the pressure mechanism 3 is rotated in the direction of the arrow (CW) by a drive motor (not shown). The With the rotation of the heating roller 1, the pressure roller 2 is rotated in the arrow direction (CCW).
Outside the heating roller 1, there is disposed a heating mechanism 5 including an exciting coil 5a that provides a predetermined magnetic field to the metal conductive layer 1c of the heating roller 1, and a magnetic core 5b that is disposed outside the exciting coil 5a. The The number of windings of the exciting coil 5a can be reduced by providing the magnetic core 5b.
In the present embodiment, the induction heating method is used as the heating mechanism 5, but the metal conductive layer 1c may be heated by radiant heat or the like.

When a high frequency current is provided from an excitation circuit (inverter circuit) (not shown), the excitation coil 5a generates a predetermined magnetic field. By providing this magnetic field, an eddy current flows in the metal conductive layer 1c, and the heating roller 1 generates heat by Joule heat generated according to the resistance of the metal conductive layer 1c.
The toner T melted by the heat from the heating roller 1 passes through the contact position (nip portion) between the heating roller 1 and the pressure roller 2 on the sheet P to which the toner T adheres, and is predetermined by the pressure roller 2. Is applied to the paper P.
Around the heating roller 1, a peeling blade 6 for peeling the paper P from the heating roller 1 in order of rotation from the nip portion of the heating roller 1 and the pressure roller 2, and the paper P from the pressure roller 2. A peeling blade 7 for peeling and a cleaning roller 8 for removing toner adhering to the heating roller 1 are arranged. Further, at a predetermined position in the longitudinal direction of the heating roller 1, a thermistor 9 for detecting the temperature in the vicinity of the peripheral surface of the heating roller 1, and detecting that the surface temperature of the heating roller 1 has risen to an abnormal temperature, are excited. A thermo stud 10 for cutting off the electric power supplied to the coil 5a is arranged.

A plurality of thermistors 9 and thermo studs 10 may be provided. Further, a plurality of peeling blades 6 and 7 may be provided if the paper P is difficult to peel, and may not be provided if the paper P is easily peeled off.
In the present embodiment, the exciting coil 5a has a shape in which an electric wire is wound around an imaginary axis, and is longer than at least the sheet passing area (area in contact with the sheet P) in the longitudinal direction of the heating roller 1. Have a length. The excitation coil 5a having such a shape can generate magnetic flux intensively and can locally generate heat on the metal conductive layer 1c of the heating roller 1.
In addition, as an electric wire of the exciting coil 5a, a litz wire in which a plurality of electric wires whose surfaces are insulated is bundled is used. By using a litz wire as the electric wire of the exciting coil 5a, the wire diameter can be made smaller than the penetration depth. Therefore, the exciting coil 5a can generate a magnetic field effectively even when an alternating current is supplied. In the present embodiment, a litz wire in which 16 copper wires having a diameter of 0.5 mm and whose surface is insulated with heat-resistant polyamideimide is bundled is used.
Further, a high frequency current in a range of 20 to 50 kHz is supplied to the exciting coil 5a as a drive frequency of the inverter circuit. Thereby, the emitted-heat amount output from the heating roller 1 can change in the range of 300-1500W.

(First embodiment)
Next, an example of the heating roller 1 will be described in more detail with reference to FIGS.
FIG. 2 is a perspective view of the heating roller 1.
As described above, the heating roller 1 includes the core rod 1a, the foam rubber layer 1b, the metal conductive layer 1c, the solid rubber layer 1d, and the release layer 1e.
The foamed rubber layer 1b is preferably formed to a thickness of 5 to 10 mm, the metal conductive layer 1c to a thickness of 10 to 100 μm, and the solid rubber layer 1d to a thickness of 100 to 200 μm. In the present embodiment, the foamed rubber layer 1b is formed with a thickness of 5 mm, the metal conductive layer 1c is formed with a thickness of 40 μm, the solid rubber layer 1d is formed with a thickness of 200 μm, the release layer 1e is formed with a thickness of 30 μm, and the heating roller 1 has a diameter of 40 mm.
Metal conductive layer 1c is formed of a conductive material (for example, nickel, stainless steel, aluminum, copper, a composite material of stainless steel and aluminum, or the like). The length L1 in the longitudinal direction of the heating roller 1 is preferably 330 mm.

FIG. 3 is a sectional view in the axial direction of the heating roller 1 of the foam rubber layer 1b and the metal conductive layer 1c.
The foamed rubber layer 1b includes an end portion 101 that is located at both ends in the axial direction and has an outer diameter D1, and a central portion 102 that is located between the end portions 101 and has an outer diameter D2. The outer diameter D2 is shorter than the outer diameter D1, and in this embodiment, the outer diameter D1 is preferably 39.7 mm and the outer diameter D2 is preferably 39.5 mm.
(1) For example, the end portion 101 has an axial length L11 including the non-sheet passing region of the heating roller 1. The non-sheet passing region is defined as a region where the paper P conveyed between the heating roller 1 and the pressure roller 2 does not pass. The length L11 is preferably 15 mm.
Further, the central portion 102 includes, for example, a sheet passing area of the heating roller 1 and has an axial length L12. The sheet passing area is defined as an area where the sheet P conveyed between the heating roller 1 and the pressure roller 2 is in contact with the heating roller 1. That is, the sheet passing area is required to have a hardness that can secure a nip width of a certain level or more in order to obtain a high-quality image by the pressure from the pressure roller 2.
The length L12 is preferably, for example, 300 mm as a length slightly longer than the length of one side of the shorter side of the A3 size paper. Since the outer diameter D2 of the central portion 102 is shorter than the outer diameter D1 of the end portion 101, that is, the outer peripheral surface of the central portion 102 is lower than the outer peripheral surface of the end portion 101, a step 103 is formed on the outer peripheral surface of the foam rubber layer 1b. The
The metal conductive layer 1c is a cylindrical endless member disposed outside the foamed rubber layer 1b and having a constant inner diameter and outer diameter in the axial direction. The metal conductive layer 1c is bonded to only the end portion 101 of the foamed rubber layer 1b disposed on the inside using, for example, a heat-resistant adhesive. By holding the end portion 101 with a predetermined tension, the region where the metal conductive layer 1c is not bonded is maintained at the same outer diameter as the outer diameter of the metal conductive layer 1c bonded to the end portion 101. ing. Needless to say, the solid rubber layer 1d and the release layer 1e disposed outside the metal conductive layer 1c are maintained at a constant outer diameter.
A gap portion 104 is formed between the central portion 102 of the foamed rubber layer 1b and the metal conductive layer 1c. The gap 104 has a height H1 in the radial direction of the heating roller 1, and in the present embodiment, the height H1 is 100 μm.
Therefore, the central part 102 not bonded to the metal conductive layer 1c can reduce the influence of thermal expansion and contraction due to heat from the metal conductive layer 1c. That is, when thermally expanded, it is possible to reduce the consumption and bubble breakage of the foamed rubber layer 1b by being restricted to the metal conductive layer 1c, and maintain a hardness that can secure a nip width of a certain level or more in order to obtain a high-quality image. it can. In addition, when the heat shrinks, it is possible to reduce the consumption and bubble breakage of the foamed rubber layer 1b due to stretching to the metal conductive layer 1c side at the point where stress is concentrated, and the fluctuation of the nip width due to the deformation of the metal conductive layer 1c. You can improve the problem.
In addition, the central portion 102 not bonded to the metal conductive layer 1c is directly subjected to stress (hereinafter referred to as an adhesion) received from the metal conductive layer 1c rotated while receiving pressure from the pressure roller 2 when bonded. Therefore, it is possible to reduce the consumption and bubble breakage of the foamed rubber layer 1b, and to maintain a longer life.

  (2) Note that the length L11 of the end portion 101 is not limited to the range of the non-sheet passing area, and is a part of the sheet passing area in addition to the non-sheet passing area as long as the defect does not occur in image formation. May be included. That is, the length L11 may be longer than the length set as the non-sheet passing area and extended to the sheet passing area side.

(3) The length L11 of the end portion 101 may be determined within a range in which sufficient adhesive strength is ensured between the foamed rubber layer 1b and the metal conductive layer 1c. That is, the range in which sufficient adhesive strength is ensured is that the metal conductive layer 1c is the foamed rubber layer 1b even when the stress from the pressure roller 2 and the rotational force from the drive circuit (not shown) are provided. For example, the length L11 is preferably 3 to 15 mm.
In addition, with the change of the length L11 of the end portion 101 as described above, the boundary between the end portion 101 and the central portion 102, that is, the step 103 also moves. For this reason, it is preferable that the length L11 is changed so that the step 103 is formed at a position where the nip width can be secured within a range where no defect occurs in the image.
In addition, since the hardness of the foam rubber layer 1b is small, even the foam rubber layer 1b having an outer diameter larger than the inner diameter of the metal conductive layer 1c can be accommodated in the metal conductive layer 1c.

(Second Embodiment)
Next, different examples of the heating roller 1 will be described in detail with reference to FIG.
As described above, the heating roller 1 includes the core rod 1a, the metal conductive layer 1c, the solid rubber layer 1d, and the release layer 1e. The foamed rubber layer 200b is disposed outside the core rod 1a and inside the metal conductive layer 1c. Have

FIG. 4 is a sectional view in the axial direction of the heating roller 1 of the foamed rubber layer 200b and the metal conductive layer 1c.
The foamed rubber layer 200b includes a central portion 201 having a first hardness and end portions 202 disposed at both ends of the central portion 201 and having a second hardness higher than the first hardness. In the present embodiment, the first and second hardnesses are durometer E type measurements, which are hardness E28 and E35, respectively.
The first hardness is determined within a range in which a nip width of a certain level or more can be secured in order to obtain a high-quality image. Note that the nip width increases as the hardness is smaller, that is, the softer.
The second hardness is determined within a range in which sufficient adhesive strength is ensured between the foamed rubber layer 200b and the metal conductive layer 1c. Note that the higher the hardness, that is, the harder, the stress due to the above-mentioned adhesion is reduced, and the foamed rubber layer 200b is less deformed (including foam breakage), so the metal conductive layer 1c is less likely to peel off.
The foamed rubber layer 200b includes a central portion 201 and end portions 202 that are independent of each other. The central portion 201 and the end portion 202 are integrally formed by bonding with a heat-resistant adhesive or the like at the boundary surface, for example. Thereby, the foamed rubber layer 200b having different hardness in the region can be easily formed.

The end portion 202 has a length L <b> 11 in the axial direction of the heating roller 1, and the central portion 201 has a length L <b> 12 in the axial direction of the heating roller 1. The length L11 of the end portion 202 may be a length including a range defined as (1) a non-sheet passing area, as in the first embodiment, and (2) in addition to the non-sheet passing area. Thus, it may be determined within a range where no defect occurs in image formation including a part of the paper passing area, or (3) within a range where sufficient adhesive strength is ensured.
The metal conductive layer 1c is bonded to the entire surface or a part of the outer peripheral surface of the foamed rubber layer 200b disposed inside using, for example, a heat-resistant adhesive. The metal conductive layer 1c is preferably bonded only to the end portion 202 of the foamed rubber layer 200b disposed inside.
Therefore, the central portion 201 can maintain a required nip width exceeding a certain level, so that a high-quality image can be obtained. Further, since the stress due to the above-described adhesion is reduced by the central portion 201 that is not bonded to the metal conductive layer 1c, consumption and bubble breakage of the foamed rubber layer 1b can be reduced, and a longer life can be maintained. Furthermore, the metal conductive layer 1c can be prevented from being damaged apart from a predetermined position where the heating roller 1 is bonded by the end portion 202 having the second hardness within a range in which sufficient bonding strength is ensured.

(Third embodiment)
Next, still another example of the heating roller 1 will be described in detail with reference to FIG.
As described above, the heating roller 1 has the core rod 1a, the metal conductive layer 1c, the solid rubber layer 1d, and the release layer 1e. The foam rubber layer 300b is disposed outside the core rod 1a and inside the metal conductive layer 1c. Have

FIG. 5 is a sectional view in the axial direction of the heating roller 1 of the foam rubber layer 300b and the metal conductive layer 1c.
The foamed rubber layer 300b includes an end portion 301 having an outer diameter D1 located at both ends in the axial direction, and a central portion 302 having an outer diameter D2 located between the end portions 301. The outer diameter D2 is shorter than the outer diameter D1, and it is preferable that the outer diameter D1 is 39.7 mm and the outer diameter D2 is 39.5 mm, as in the first embodiment. Like the foamed rubber layer 200b, the foamed rubber layer 300b is composed of independent end portions 301 and a central portion 302, and is integrally bonded by a heat resistant adhesive or the like at the boundary surface. Is formed.
The end portion 301 has a length L11 determined in the predetermined range described above, and the central portion 302 has a length L12 determined in the predetermined range described above.
Further, similarly to the second embodiment, the central portion 302 has a first hardness, and the end portion 301 has a second hardness larger than the first hardness.
The metal conductive layer 1c is bonded to only the end 301 of the foamed rubber layer 300b disposed on the inner side using, for example, a heat-resistant adhesive.
A gap portion 303 is formed between the central portion 302 and the metal conductive layer 1c. The gap portion 303 has a height H1 in the radial direction of the heating roller 1, and the height H1 is preferably 100 μm.

Therefore, the central portion 302 that is not bonded to the metal conductive layer 1c can reduce the consumption and bubble breakage of the foamed rubber layer 1b due to thermal expansion and contraction, and the problem of fluctuation of the nip width due to deformation of the metal conductive layer 1c. Can be improved.
Further, since the center portion 302 can maintain a required nip width exceeding a certain level, a high-quality image can be obtained. Further, in the central portion 302 that is not bonded to the metal conductive layer 1c, the stress due to the bonding described above is reduced, so that the consumption of the foamed rubber layer 1b can be reduced and a longer life can be maintained. Furthermore, at the end portion 301 having the second hardness within a range in which sufficient adhesive strength is ensured, the metal conductive layer 1c can be prevented from being damaged apart from a predetermined position where the heating roller 1 is bonded.
Further, as shown in FIG. 6, a groove having a predetermined length in the axial direction of the heating roller 1 (for example, a distance L11 in the axial direction of the end portion 301) is provided on the outer peripheral surface of the end portion 301. A plurality of vent holes 304 can be formed. The vent hole 304 is formed on the outer peripheral surface of the end 301, for example, in a semicircular shape that is recessed toward the axis of the rotating roller, as viewed from the direction of arrow A in the drawing.

The metal conductive layer 1c is bonded to a region of the end portion 301 where the air holes 304 are not formed using, for example, a heat-resistant adhesive.
The bubbles formed in the foamed rubber layer 300b store the heat provided by the metal conductive layer 1c, so that this heat is used more efficiently. However, in the environment where the thermal expansion and contraction of the foamed rubber layer 300b is restricted by the adhesion with the metal conductive layer 1c, the above-described problem may occur.
The air holes 304 can conduct heat existing in the region where the metal conductive layer 1 c and the foamed rubber layer 300 b face each other, that is, in the gap portion 303, to the outside of the gap portion 303. For this reason, consumption and bubble breakage of the foamed rubber layer 1b due to thermal expansion and thermal contraction of the foamed rubber layer 300b can be reduced, and the problem of fluctuation of the nip width due to deformation of the metal conductive layer 1c can be improved.

Further, as shown in FIG. 7, a plurality of vent holes 305 having a predetermined length in the axial direction of the heating roller 1 can be formed in the end portion 301. Similarly to the above-described vent hole 304, this vent hole 305 can also guide the heat present in the gap portion 303 to the outside of the gap portion 303.
Since the end 301 where the vent hole 305 is formed is maintained in a circular shape having a constant outer diameter, an adhesive can be applied to the entire outer peripheral surface. For this reason, the labor of the manufacturing process can be reduced and the adhesive strength is further increased.
Needless to say, the amount of heat required for fixing can be secured by adjusting the size of the gap portions 304 and 305.
Further, although not shown, the air hole 305 having a predetermined length in the axial direction of the heating roller 1 (for example, the axial distance L12 of the central portion 302) is formed in the central portion 302 of the foamed rubber layer 300b, and ends. It may be connected to a vent hole 305 formed in 301.

(Fourth embodiment)
Next, still another example of the heating roller 1 will be described in detail with reference to FIG.
As described above, the heating roller 1 has the core rod 1a, the solid rubber layer 1d, and the release layer 1e, and has the foam rubber layer 400b and the metal conductive layer 400c outside the core rod 1a.

FIG. 8 is a sectional view in the axial direction of the heating roller 1 of the foam rubber layer 400b and the metal conductive layer 400c.
The foamed rubber layer 400 b has a constant outer diameter in the axial direction of the heating roller 1.
The metal conductive layer 400 c is a cylindrical endless member having a constant outer diameter in the axial direction of the heating roller 1. The metal conductive layer 400c includes an end portion 401 having a thickness D3, which is located at both ends in the axial direction, and a central portion 402 having a thickness D4, which is located between the end portions 401.
The thickness D3 is thicker (longer) than the thickness D4, and in this embodiment, the thickness D3 is 100 μm and the thickness D4 is 40 μm.

The end portion 401 has a length L11 determined in the predetermined range described above, and the central portion 402 has a length L12 determined in the predetermined range described above.
The foamed rubber layer 400b is bonded to the end 401 of the metal conductive layer 400c disposed on the outside using, for example, a heat-resistant adhesive. By holding the end portion 401 with a predetermined tension, the central portion 402 where the metal conductive layer 400 c is not bonded is maintained at the same outer diameter as the outer diameter of the end portion 401. Needless to say, the solid rubber layer 1d and the release layer 1e disposed outside the metal conductive layer 1c are maintained at a constant outer diameter.

Therefore, a gap portion 403 is formed between the center portion 402 of the foamed rubber layer 400b and the metal conductive layer 400c. It is preferable that the gap portion 403 has a height H2 in the radial direction of the heating roller 1 and is supported by the end 401 to maintain the height H2 at 60 μm.
Therefore, the adhesive strength between the foamed rubber layer 400b and the metal conductive layer 400c is further increased by increasing the thickness of the metal conductive layer at the end 401 bonded to the foamed rubber layer 400b. For this reason, it can prevent that the metal conductive layer 400c leaves | separates from the predetermined position where the heating roller 1 is adhere | attached, and is damaged.
In addition, the gap portion 403 can reduce consumption and bubble breakage of the foamed rubber layer 400b due to thermal expansion and contraction, and can improve the problem of nip width variation due to deformation of the metal conductive layer 400c. Furthermore, since the foamed rubber layer 400b is not bonded to the central portion 402 of the metal conductive layer 400c, the stress due to the above-described bonding can be reduced, and consumption and bubble breakage of the foamed rubber layer 400b can be reduced, and a longer life can be maintained. it can.
The end 401 having the thickness D4 is a method of vapor-depositing a metal member having a difference between the thicknesses D3 and D4 on a cylindrical metal member having a thickness D3 having a length L1, or bonding with an adhesive or the like. May be formed integrally with each other.

(Fifth embodiment)
Next, still another example of the heating roller 1 will be described in detail with reference to FIG.
As described above, the heating roller 1 has the core rod 1a, the solid rubber layer 1d, and the release layer 1e, and has the foam rubber layer 500b and the metal conductive layer 500c outside the core rod 1a.

FIG. 9 is a sectional view in the axial direction of the heating roller 1 of the foam rubber layer 500b and the metal conductive layer 500c.
The foam rubber layer 500b has a constant outer diameter D5 in the axial direction of the heating roller 1.
The metal conductive layer 500c is a cylindrical endless member having a constant outer diameter and an inner diameter D6 in the axial direction of the heating roller 1. The thickness of the metal conductive layer 500c is preferably 40 μm.
The inner diameter D6 is longer than the outer diameter D5. In this embodiment, the inner diameter D6 is 39.7 mm, and the outer diameter D5 is 39.5 mm. Therefore, when the foamed rubber layer 500b is disposed inside the metal conductive layer 500c, a gap is formed between them.
The heating roller 1 includes an end region 501 located at both ends in the axial direction and a central region 502 located between the end regions 501. The end region 501 has a length L11 determined in the above-described predetermined range, and the central region 502 has a length L12 determined in the above-described predetermined range.
In this end region 501, a sleeve (spacer) 503 is disposed between the foamed rubber layer 500b and the metal conductive layer 500c. The sleeve 503 can be formed in a cylindrical shape having a height of L11. However, the sleeve 503 is not limited to a cylindrical shape, and may be formed in, for example, a rectangle having a certain thickness and a length equal to or less than the circumference of a circle having a length L11 and a width D5. In this case, the rectangular sleeve 503 is rolled and accommodated between the foamed rubber layer 500b and the metal conductive layer 500c.

The diameter and thickness D7 of the sleeve 503 are calculated from the difference between the outer diameter D5 and the inner diameter D6, and are 100 μm in the present embodiment.
The sleeve 503 is preferably made of a material that is not easily affected by thermal deformation, thermal contraction, thermal expansion, or the like, for example, a resin such as polyimide, and may include a metal used for the metal conductive layer 500c.
The sleeve 503 is bonded to the foamed rubber layer 500b and the metal conductive layer 500c using, for example, a heat-resistant adhesive. That is, the foamed rubber layer 500b and the metal conductive layer 500c are not directly bonded.
Accordingly, a gap portion 504 is formed in the central region 502 of the heating roller 1 between the foamed rubber layer 500b and the metal conductive layer 500c. The gap portion 504 has a height D7 equal to the thickness of the sleeve 503 in the radial direction of the heating roller 1, and the height D7 is preferably supported by the sleeve 503 and maintained at 100 μm.

Therefore, the foamed rubber layer 500b and the metal conductive layer 500c bonded by the sleeve 503 are less affected by heat deformation, thermal contraction, thermal expansion, and the like. In addition, the foamed rubber layer 500b that is not bonded to the metal conductive layer 500c is unlikely to be limited in thermal expansion or contraction by the metal conductive layer 1c. In addition, the stress due to the adhesion described above can be reduced in the central portion of the foamed rubber layer 500b. For this reason, consumption and foam breakage of the foamed rubber layer 1b can be reduced, and the problem of fluctuation of the nip width due to deformation of the metal conductive layer 1c can be improved.
On the outer peripheral surface of the sleeve 503, as shown in FIG. 10, a plurality of ventilation holes 505, which are grooves provided with a recess having a predetermined length (for example, length L11) in the axial direction of the heating roller 1, are formed. it can. The vent hole 505 is formed on the outer peripheral surface of the sleeve 503, for example, in a semicircular shape that is recessed toward the axis of the rotating roller. The vent hole 505 can guide heat existing in the gap portion 504 to the outside of the gap portion 504. The metal conductive layer 1c is bonded to a region of the sleeve 503 where the air holes 505 are not formed using, for example, a heat-resistant adhesive.

Therefore, the heat existing in the gap portion 504 is released from the vent hole 505. For this reason, consumption and bubble breakage due to thermal expansion and contraction of the foamed rubber layer 500b can be reduced, and the problem of fluctuation of the nip width due to deformation of the metal conductive layer 1c can be improved.
Further, as shown in FIG. 11, the sleeve 503 has a predetermined length in the axial direction of the heating roller 1 (for example, the axial distance L11 of the sleeve 503), and the axial direction of the heating roller 2 as shown in FIG. A plurality of vent holes 506 can be formed by cutting out the outer peripheral surface of the sleeve 503 in a linear shape inclined at a predetermined angle. The vent hole 506 can guide heat existing in the gap portion 504 to the outside of the gap portion 504 in the same manner as the vent hole 505 described above.
Needless to say, by adjusting the size of the gap portion 504, the amount of heat released can be adjusted, and the amount of heat required for fixing can be secured.

(Sixth embodiment)
Next, still another example of the heating roller 1 will be described in detail with reference to FIG.
As described above, the heating roller 1 includes the solid rubber layer 1d and the release layer 1e, and further includes the core rod 600a, the foamed rubber layer 600b and the metal conductive layer 600c disposed outside the core rod 600a. .

FIG. 12 is a sectional view in the axial direction of the heating roller 1 of the core rod 600a, the foam rubber layer 600b, and the metal conductive layer 600c.
The core rod 600a includes an end portion 601 that is located at both ends in the axial direction and has an outer diameter D8, and a central portion 602 that is located between the end portions 601 and has an outer diameter D9. The outer diameter D8 is longer than the outer diameter D9. The difference between the outer diameter D8 and the outer diameter D9 will be described in detail later, but is determined within a range where a nip width of a certain level or more can be secured in order to obtain a high-quality image according to the material of the foamed rubber layer 600b. The For example, it is preferable to have a difference of 1 mm or more.
The end portion 601 has a length L11 determined in the above-described predetermined range, and the central portion 602 has a length L12 determined in the above-described predetermined range. Further, the core rod 600a preferably has a shape having a hollow portion inside, for example, a hollow portion that penetrates both end portions 601 and the central portion 602.

The foamed rubber layer 600b is a cylindrical foam having a constant outer diameter in the axial direction, and is bonded to the core rod 600a using, for example, a heat-resistant adhesive. Or a foam may be produced | generated by the core rod 600a, and it may be formed in a fixed outer diameter. In the present embodiment, the outer diameter of the foam rubber layer 600b is 39.7 mm.
The foamed rubber layer 600b has a length L11, an end portion 603 located outside the end portion 601 of the core rod 600a, and a center having a length L12 and located outside the center portion 602 of the core rod 600a. Part 604.
The end 603 of the foam rubber layer 600b has a thickness D10. The central portion 604 of the foamed rubber layer 600b has a thickness D11 that is thicker (larger) than the thickness D10. The metal conductive layer 600c, which is a cylindrical endless member having a constant outer diameter and inner diameter, is bonded to the entire surface of the foam rubber layer 600b with a heat-resistant adhesive or the like.
By forming the central portion 604 of the foamed rubber layer 600b with a thicker thickness, the repulsive force against the pressure of the pressure roller 2, that is, the resistance force corresponding to the hardness of the core rod 600a can be absorbed. Accordingly, the central portion 604 having a thickness D11 that is thicker than the thickness D10 has a hardness lower than that of the end portion 603. That is, the shape of the central portion 604 can be changed flexibly.
Therefore, the central portion 604 can secure a nip width of a certain level or more in order to obtain a high quality image.

As shown in FIG. 13, the heating roller 1 includes a cylindrical foamed rubber layer 700b having a constant outer diameter and inner diameter in the axial direction of the heating roller 1 between the core rod 600a and the metal conductive layer 600c. You may have.
The foamed rubber layer 700b is bonded only to the end portion 601 of the core bar 600a with a heat-resistant adhesive or the like. The metal conductive layer 600c is bonded to the entire surface of the foam rubber layer 700b with a heat-resistant adhesive or the like. Between the foamed rubber layer 700b and the central portion 602 of the core rod 600a, a gap portion 605 corresponding to the difference between the outer diameter D8 and the outer diameter D9 of the core rod 600a is formed.
A repulsive force corresponding to the hardness of the core rod 600a is absorbed by the gap portion 605, and a nip width of a certain level or more can be secured in the central portion of the foamed rubber layer 600b having a low hardness in order to obtain a high-quality image.
A plurality of vent holes 606 having a predetermined length in the axial direction of the heating roller 1 (for example, the axial distance L11 of the end portion 601) can be formed in the end portion 601 of the core rod 600a. The vent hole 606 can guide heat existing in the gap portion 605 to the outside of the gap portion 605.
Therefore, the hardness of the heating roller 1 increases due to thermal expansion, and the problem that a nip width of a certain level or more cannot be secured can be improved.

Note that the metal conductive layer 600c shown in FIG. 12 may be bonded only to the end portion 603 of the foamed rubber layer 600b. Further, the metal conductive layer 600c shown in FIG. 13 may be bonded only to the end portion of the foamed rubber layer 700b, that is, the region of the length L11 from the longitudinal end of the foamed rubber layer 700b. The core rod 600a, the foam rubber layer 700b, and the metal conductive layer 600c are bonded only in the region having the length L11 determined in the predetermined range.
Therefore, since the stress due to the above-described adhesion is reduced, foam breakage and consumption of the foamed rubber layer 600b are reduced, and a longer life is maintained.

(Seventh embodiment)
Next, still another example of the heating roller 1 will be described in detail with reference to FIGS.
As shown in FIG. 14, the heating roller 1 has a foam rubber layer 1b, and has a core rod 800a disposed inside the foam rubber layer 1b and a metal conductive layer 800c disposed outside. A solid rubber layer 1d and a release layer 1e may be formed outside the metal conductive layer 800c.

FIG. 15 shows a perspective view of the core rod 800a.
The core rod 800a is formed in a cylindrical shape and has a hollow portion 801 inside. The hollow portion 801 is connected to the outside of the outer peripheral surface by a ventilation port 802 formed in the core rod 800a.
The outer peripheral surface of the core bar 800a is bonded to the foamed rubber layer 1b with a heat-resistant adhesive or the like. When stress such as pressure is applied from the metal conductive layer 800c or the pressure roller 2, the air contained in the foamed rubber layer 1b is guided from the hollow portion 801 to the outside of the heating roller 1 through the ventilation port 802. . Therefore, the air thermally expanded in the foamed rubber layer 1b is guided from the hollow portion 801 to the outside of the heating roller 1, so that the hardness of the heating roller 1 is larger than the hardness range for ensuring the required nip width. Can be prevented.

FIG. 16 is a perspective view of the metal conductive layer 800c.
The metal conductive layer 800c is a cylindrical endless member having a constant outer diameter and inner diameter. The metal conductive layer 800c includes a first layer 803 made of a first material and a second layer 804 made of a second material located around the first layer 803.

The first layer 803 is formed in a cylindrical shape having a thickness D12, and the second layer 804 is formed in a cylindrical shape having a thickness D13. The hardness of the metal conductive layer 800c is adjusted by arbitrarily selecting the thicknesses D12 and 13 according to the first and second materials. The metal conductive layer 800c preferably has a small hardness in order to reduce the difference from the hardness of the foamed rubber layer 1b and prevent the foamed rubber layer 1b from being consumed or broken by stress.
In the present embodiment, the first material is nickel, the second material is copper, and the first and second layers 803 and 804 are each formed to 20 μm. The combination of the first and second materials is not limited to this, and can be arbitrarily selected from nickel, stainless steel, aluminum, copper, and a composite material of stainless steel and aluminum. The first and second layers 803 and 804 may be bonded at the boundary surface using a heat-resistant adhesive or the like, or may be integrally formed by vapor deposition or the like.

The metal conductive layer 800c is bonded to the entire surface of the foam rubber layer 1b with a heat-resistant adhesive or the like. The metal conductive layer 800c may be bonded only to the end portion of the foamed rubber layer 1b, that is, the region of the length L11 from the longitudinal end of the foamed rubber layer 1b.
In this embodiment, the metal conductive layer 800c has been described as having a two-layer structure, but may have a structure of three or more layers. The material of each layer can be arbitrarily selected from stainless steel, nickel, stainless steel, aluminum, copper, and a composite material of stainless steel and aluminum.

  In addition, as shown in FIG. 17, the metal conductive layer 800c includes a first inner layer 805 formed at both ends in the longitudinal direction of the heating roller 1, a second inner layer 806 formed at the center in the longitudinal direction, The first outer layer 807 formed outside the first inner layer 805 and the second outer layer 808 formed outside the second inner layer 806 are formed of predetermined materials. The first and second inner layers 805 and 806 and the first and second outer layers 807 and 808 may be bonded to each other using a heat-resistant adhesive or the like at the boundary surface, or integrally formed by vapor deposition or the like. May be.

The first inner layer 805 and the first outer layer 807 each include a region (first region) having a length L11 determined within the predetermined range described above, and the second inner layer 806 and the second outer layer 808 are , Each of which includes a region (second region) having a length L12 determined within the predetermined range described above. In the second region where high adhesive strength (fixed strength) with the foamed rubber layer 1b is required, it is required to increase the hardness, and in the first region where a certain nip width is required, the hardness is required. Is required to be small. Therefore, the hardness of the metal conductive layer 800c can be adjusted as described above by arbitrarily selecting the material to be configured.
In the present embodiment, the first inner layer 805, the second inner layer 806, and the first outer layer 807 are nickel, and the second outer layer 808 is copper, and each is formed in a cylindrical shape having a thickness of 20 μm. Accordingly, the hardness of the first region is greater than the hardness of the second region.
Further, the combination of materials of the first and second inner layers 805 and 806 and the first and second outer layers 807 and 808 is not limited to this, and may be arbitrarily selected from nickel, stainless steel, aluminum, copper, and a composite material of stainless steel and aluminum. You can choose. The first and second inner layers 805 and 806 and the first and second outer layers 807 and 808 may be bonded to each other using a heat-resistant adhesive or the like at the boundary surfaces, or may be integrated by vapor deposition or the like. It may be formed.
The metal conductive layer 800c including at least two or more layers described above may be provided outside the core rod 1a and the foamed rubber layer 1b described above.

The core rod, the foam rubber layer, and the metal conductive layer described in the first to seventh embodiments can be used in any combination. For example, the heating roller 1 may include the foamed rubber layer 1b shown in FIG. 3 and the core rod 800a and the metal conductive layer 800c shown in FIGS. Moreover, the heating roller 1 provided with the foamed rubber layer 300b shown in FIG. 5 and the core rod 800a and the metal conductive layer 800c shown in FIGS.
The configuration of the heating roller 1 described in the first to seventh embodiments may be applied to the pressure roller 2.

(Eighth embodiment)
Next, still another example of the heating roller will be described with reference to FIGS.
FIG. 18A is a sectional view of the heating roller in the axial direction.
The heating roller 20 has a metal conductive layer 20c and a foamed rubber layer 20b. A core rod 1a may be provided inside the foamed rubber layer 20b, and a solid rubber layer 1d and a release layer 1e may be provided outside the metal conductive layer 20c.

The metal conductive layer 20c has an inner peripheral surface with an inner diameter D14 uniformly.
The foamed rubber layer 20b includes an end portion 21b having the largest outer diameter D14 and a central portion 22b having the smallest outer diameter D15.
A cone portion 23b whose outer diameter gradually decreases in the axial direction as it approaches the center is located inside the end portion 21b, and a cone portion 24b whose outer diameter gradually decreases in the axial direction as it approaches the center at both ends of the central portion 22b. Is formed. More specifically, the outer diameter of the cone portion 23b gradually decreases from the maximum outer diameter D14 to the outer diameter D16, and the outer diameter of the cone portion 24b gradually decreases from the outer diameter D16 to the minimum outer diameter D15. The outer diameter D16 has a predetermined value smaller than the outer diameter D14 and larger than the outer diameter D15.
The outer peripheral surfaces of the cone portions 23b and 24b are conical (tapered) with the outer diameter gradually decreasing at a constant rate, as shown linearly in the sectional view. Hereinafter, the taper surface will be described. Hereinafter, a surface having a constant outer diameter in the axial direction, such as the end portion 21b and the central portion 22b, will be described as a cylindrical surface.

The end 21b has a length L13 in the axial direction, and the outer peripheral surface is in contact with the metal conductive layer 20c. The metal conductive layer 20c and the end portion 21b are bonded to the entire surface or a part of the contact portion using, for example, a heat-resistant adhesive.
Further, the foamed rubber layer 20b has an axial length L14 in a portion that is not in contact with the metal conductive layer 20c. (4) The length L14 is the sum of the axial lengths of the central portion 22b and the cone portions 23b, 24b, and the length L13 may be within a range in which (3) sufficient adhesive strength is ensured. .
Further, there is a step 25 between the end portion 21b and the cone portion 23b, and when a predetermined pressure is provided from the pressure roller 2, a step may be formed on the surface of the metal conductive layer 20c. . For this reason, the step 25 is preferably outside the image forming area.

  Thus, the metal conductive layer 20c is not bonded to the cone portions 23b and 24b of the foam rubber layer 20b, and a gap may be formed between the foam rubber layer other than the end portion 21b and the metal conductive layer 20b. preferable. The foamed rubber layer 20b is preferably not bonded to the end portion 21b and the cone portions 23b and 24b of the metal conductive layer 20c, and a gap is preferably formed therebetween. In the present embodiment, the outer diameter D14 and the outer diameter D15 have a difference H3 of at least a diameter of 0.1 to 2 mm (that is, a radius of 0.05 to 1 mm).

The foamed rubber layer 20b is symmetrical with respect to the shaft 26, and a cross section perpendicular to the shaft is a circle having a predetermined radius. The foamed rubber layer 20b is symmetric with respect to the radial center line 27.
Note that the end portion and the cone portion as the foamed rubber layer may be integrally formed, or a plurality of members may be combined. When combining a plurality of members, the combined portion may be bonded, but a slight gap may be provided. In this case, by using the shaft shown in FIG. 15, an air passage can be formed between the outside of the roller and the gap, and the air pressure inside the roller can be adjusted.

By the way, there is a problem that the material to be transferred conveyed between the heating roller and the pressure roller while being supplied with predetermined heat and pressure does not absorb the expansion due to the expansion and the surface becomes wrinkled.
The heating roller 20 of the present embodiment includes a foamed rubber layer 20b having an outer diameter that is largest at both ends and gradually decreases toward the center, and between the pressure roller 2 that provides a predetermined tension. When the material to be transferred passes, the transfer speed of the material to be transferred becomes faster on the outer side than on the center.
Therefore, the transfer material, which is located between the heating roller 20 and the pressure roller 2 and is moved by the rotation of the roller, passes between the rollers so as to be pulled toward both ends in the axial direction, so that a ridge is formed. Can be suppressed. In addition, when the center of the transfer material passes near the center line 915, generation of biased stress can be prevented, so that the transfer material is moved in a direction perpendicular to the axis, and wrinkles are not easily formed.

  In addition, the central portion 22b and the cone portions 23b and 24b that are not bonded to the metal conductive layer 20c are less affected by thermal expansion and contraction due to heat from the metal conductive layer 20c. That is, when thermally expanded, it is possible to reduce the consumption and bubble breakage of the foamed rubber layer 20b by being restricted to the metal conductive layer 20c, and to maintain a hardness that can secure a nip width of a certain level or more in order to obtain a high-quality image. it can. Furthermore, since the stress due to the above-described adhesion is reduced, foam breakage and consumption of the foamed rubber layer 20b are reduced, and a longer life is maintained.

  The metal conductive layer 20c only needs to have an inner diameter that is equal to or smaller than the outer diameter D14 of the end portion 21b. It may be arranged. That is, the foamed rubber layer 20b may be in contact with the metal conductive layer 20c on the outer peripheral surface of a part or all of the region defined by the length L14. Even if it is such a structure, the same effect is acquired.

Next, a modified example of the foam rubber layer 20b will be described.
As shown in FIG. 18B, the foamed rubber layer 31b includes an end portion 311b having a cylindrical surface with a maximum outer diameter D14, a central portion 312b having a cylindrical surface with a minimum outer diameter D15, an end portion 311b, and a central portion 312b. And a cone portion 313b having a tapered surface with an outer diameter gradually decreasing toward the central portion 312b. It is also symmetric about the axis and symmetric about the center line of the diameter.

  As shown in FIG. 18 (c), the foamed rubber layer 32b includes an end portion 321b having a cylindrical surface with a maximum outer diameter D14 and a cone portion having a tapered surface with the outer diameter gradually decreasing toward the minimum outer diameter D15. 322b is included. It is also symmetric about the axis and symmetric about the center line of the diameter.

  As shown in FIG. 18D, the foamed rubber layer 33b includes an end portion 331b having a cylindrical surface with a maximum outer diameter D14, a central portion 332b having a cylindrical surface with a minimum outer diameter D15, an end portion 331b, and a central portion 332b. And cone portions 333b and 334b having tapered surfaces whose outer diameters gradually decrease toward the central portion 332b. Further, the central portion 332b has a predetermined length L15, the cone portion 333b has a predetermined length L16, and the cone portion 334b has a predetermined length L17 so that the outer diameter of the foamed rubber layer 33b decreases gently toward the center. Respectively in the axial direction. It is also symmetric about the axis and symmetric about the center line of the diameter.

  As shown in FIG. 18 (e), the foamed rubber layer 34b is positioned at both ends of the end portion 341b having a cylindrical surface with the maximum outer diameter D14, the central portion 342b having the cylindrical surface with the minimum outer diameter D15, and the central portion 342b. A cone portion 343b having a tapered surface whose outer diameter gradually decreases toward the central portion 342b, and a cylinder having an outer diameter D16 which is located outside the cone portion 343b and which is smaller than the outer diameter D14 and larger than the outer diameter D15. And a cylindrical portion 344b having a surface. Note that a step 345 is formed between the cylindrical portion 344b and the end 341b, and the step 955 is preferably a position where no defect occurs in image formation, for example, a predetermined position in a non-sheet passing area. It is also symmetric about the axis and symmetric about the center line of the diameter.

  As shown in FIG. 18 (f), the foamed rubber layer 35b includes an end 351b having a cylindrical surface with a maximum outer diameter D14 and a central portion 352b having a minimum outer diameter D15 at the center in the axial direction. The outer peripheral surface of the central portion 352b has an outer diameter that gradually decreases from both ends toward the center at a predetermined rate, as shown in a curve in the cross-sectional view. Such a surface is hereinafter referred to as a curved surface portion. I will explain. It is also symmetric about the axis and symmetric about the center line of the diameter.

  As shown in FIG. 18 (g), the foamed rubber layer 36b has a maximum outer diameter D17 at both ends in the axial direction and a minimum outer diameter D15 at the center. It has a curved surface portion 361b whose outer diameter gradually decreases toward the center at a ratio. It is also symmetric about the axis and symmetric about the center line of the diameter.

  Further, unlike the foamed rubber layers 31b to 35b described above, the foamed rubber layer 36b is not formed on the cylindrical surface as a predetermined region in contact with the metal conductive layer 20c at both ends. By forming the region of the length L13 to have an outer diameter larger than the inner diameter D14 of the metal conductive layer 20c disposed on the outside, a predetermined region for contacting the metal conductive layer 20c by so-called tight fitting can be secured.

  When the foamed rubber layers 31b to 36b are arranged inside the metal conductive layer 20c, the whole or a part of the portions in contact with the metal conductive layer 20c is bonded using, for example, a heat-resistant adhesive. .

  The end portions 311b, 321b, 331b, 341b, and 351b preferably have a length L13 in the axial direction similarly to the end portion 21b, and preferably have a length L14 between both end portions.

As described above, foamed rubber layer 31b~36b is greatest at both ends, because it has a progressively smaller outside diameter toward the center, towards the outside than in the center, faster transport speed of the transfer material Become.

(Ninth embodiment)
Next, still another example of the heating roller will be described with reference to FIGS.
The heating roller 40 includes the metal conductive layer 40c and the foamed rubber layer 20b described above as the foamed rubber layer having an outer diameter that is the largest at both ends and gradually decreases toward the center. The core rod 1a may be disposed inside the foamed rubber layer 20b, and the solid rubber layer 1d and the release layer 1e may be disposed outside the metal conductive layer 40c.

FIG. 19A shows an axial sectional view of the foamed rubber layer 20b and the metal conductive layer 40c, and FIG. 19B shows a schematic perspective view of the metal conductive layer 40c.
For example, as shown in FIG. 18A, the foamed rubber layer 20b has an outer diameter that gradually decreases in the axial direction from the maximum outer diameter D14 at the end toward the central minimum outer diameter D15.

As shown in FIG. 19B, the metal conductive layer 40c includes an end portion 41c having a cylindrical surface with a maximum inner diameter D14 and a central portion 42c having a minimum inner diameter D18 at the center in the axial direction. The central portion 42c includes a curved surface portion whose inner diameter gradually decreases from both ends toward the minimum inner diameter D18. The metal conductive layer 40c is formed to have a constant thickness in the axial direction, for example, 40 μm. Therefore, the outer peripheral surface of the metal conductive layer 40c is also formed of a curved surface portion whose outer diameter is the largest at both ends and gradually decreases toward the center, like the inner peripheral surface.
The inner diameter D18 of the metal conductive layer 40c is larger than the minimum outer diameter D15 of the foam rubber layer 20b.

As shown in FIG. 19A, the end 41c of the metal conductive layer 40c has a length L13 in the axial direction, and is in contact with the foamed rubber layer 20b on the inner peripheral surface. The metal conductive layer 40c and the foamed rubber layer 20b are bonded to the entire surface or a part of the contact portion using, for example, a heat-resistant adhesive.
Central portion 42c of the metal conductive layer 40c has a length L14 in the axial direction, does not adhere as foamed rubber 20b, it is preferable that the gap is formed between.

  In the present embodiment, the inner diameter D18 and the outer diameter D15 have a difference H4 of at least 0.1 to 2 mm in diameter (that is, a radius of 0.05 to 1 mm). The sum of the end portion 41c and the central portion 42c, that is, the axial length of the metal conductive layer 40c is L1, and is preferably 330 mm, for example.

  In addition, a boundary 43 is formed between the end portion 41c and the central portion 42c, and this is provided between the boundary 43 and the pressure roller 2 by applying pressure from the pressure roller 2. There is a risk of causing image defects in the transferred material that has passed. For this reason, it is preferable that L14 is determined to have a predetermined length so that the boundary 43 is at a predetermined position where no defect occurs in image formation. Therefore, as described above, (4) the length L14 is longer than the sheet passing area and may include the sheet passing area and the non-sheet passing area. (3) The length L13 may be determined within a range in which sufficient adhesive strength is ensured.

  As described above, the heating roller 40 has outer peripheral surfaces with different outer diameters in the axial direction, and has an outer diameter that is largest at both ends and gradually decreases toward the center. Thus, the transfer speed of the transfer material is faster at the end (outer side) than at the center (inner side) in the axial direction. Accordingly, since the transferred material to be transferred passes between the heating roller 40 and the pressure roller 2 so as to be pulled to both ends in the axial direction, generation of wrinkles can be suppressed.

Next, with reference to FIG. 19C, another example of a metal conductive layer that is the largest at both ends and gradually decreases toward the center will be described.
The metal conductive layer 44 c has an outer peripheral surface composed only of the curved surface portion 45.
Further, the metal conductive layer 44c may be provided with, for example, a foam rubber layer 36b shown in FIG. The foamed rubber layer 36b is bonded to, for example, an end portion of the metal conductive layer 44c defined by the length L13, is not bonded to the central portion of the metal conductive layer 44c including at least the paper passing region, and has a gap therebetween. Is preferred.
With this configuration, no boundary is formed on the surface of the metal conductive layer 44c, and there is no possibility that an image defect is formed.

In the present embodiment, the foamed rubber layer 20b has been described as an example. For example, any one of the foamed rubber layers 31b to 36b shown in FIGS. 18 (b) to 18 (f) is used as a metal conductive layer. It may be provided inside 40c.
Needless to say, the metal conductive layers 40c and 44c are symmetrical about the axis and symmetrical about the radial center line.

(Tenth embodiment)
Next, still another example of the heating roller will be described with reference to FIGS.
As shown in FIG. 20A, the heating roller 50 includes a central portion 51 having a length L12 in the axial direction, and end portions 52 and 53 disposed at both ends of the central portion 51 and having a length L11. The central portion 51 has a third hardness, and the end portions 52 and 53 have a fourth hardness larger (harder) than the third hardness.

The heating roller 50 includes, for example, a core bar 50a, a foam rubber layer 50b, and a metal conductive layer 50c as shown in FIG.
The core rod 50a has the outer diameter D20 uniformly in the axial direction.
The foamed rubber layer 50b includes a central foamed rubber layer 51b having a minimum outer diameter D21 and a length L12 corresponding to the central part 51, and end foamed rubber layers 52b and 53b having a maximum outer diameter D22. Partial foamed rubber layers 52b and 53b have lengths L11 corresponding to end portions 52 and 53, respectively.
Therefore, the central foamed rubber layer 51b has a uniform thickness (D21-D20) / 2 in the circumferential direction, and the end foamed rubber layers 52b, 53b have a uniform thickness (D22-D20) / in the circumferential direction. 2
The metal conductive layer 50c has the inner diameter D23 uniformly in the axial direction.
Thus, the heating roller 50 having different hardness at the central portion and the end portion has a foamed rubber layer having different outer diameters at the central portion and the end portion inside the metal conductive layer.

Next, the relationship between the foam rubber layer 50b and the metal conductive layer 50c will be described.
As shown in FIG. 20B, the outer diameter D22 of the end foam rubber layers 52b and 53b is larger than the inner diameter D23 of the metal conductive layer 50c, and the outer diameter D21 of the center foam rubber layer 51b is larger than the inner diameter D23. small. That is, D21 <D23 <D22 holds.
Therefore, the end foamed rubber layers 52b and 53b are fitted to the metal conductive layer 50c by tight fitting, and the fourth hardness having a predetermined magnitude hardness according to the interference 54 which is the difference (D22−D23) / 2 between them. Of hardness. Further, a gap 55 (see FIG. 20A) that is the difference (D23−D21) / 2 between the center foam rubber layer 51b and the metal conductive layer 50c is formed. A configuration having a gap at the center and tightly fitting at the end portion will be described below as a type α.

  On the other hand, as shown in FIG. 20C, when the outer diameter D21 of the central foam rubber layer 51b is equal to the inner diameter D23 of the metal conductive layer 50c, there is a gap between the metal conductive layer 50c and the foam rubber layer. However, the end portions 52 and 53 of the heating roller 50 have a fourth hardness larger than the third hardness of the central portion 51 corresponding to the interference 54. That is, D21 = D23 <D22 holds. A configuration in which there is no gap at the center and is tightly fitted at the end will be described below as type β.

  In addition, as shown in FIG. 20D, when the outer diameter D21 of the central foam rubber layer 51b is larger than the inner diameter D23 of the metal conductive layer 50c, there is no gap between the metal conductive layer 50c and the foam rubber layer. The third hardness at the center and the fourth hardness at the end of the heating roller 50 have a difference corresponding to the difference between the interference 54 at the end and the interference 56 at the center. That is, D23 <D21 <D22 holds. In this way, a configuration in which the fitting is performed at the center and the end will be described below as a type γ.

  Further, as shown in FIG. 20 (e), when the outer diameter D22 of the end foam rubber layers 52b and 53b is equal to the inner diameter D23 of the metal conductive layer 50c, the metal conductive layer 50c and the central foam rubber layer 51b A gap is formed between the central portion 51 of the heating roller 50 and a third hardness smaller than the fourth hardness of the end portion corresponding to the difference between the outer diameter D21 of the central portion of the foamed rubber layer and the outer diameter D22 of the end portion. Has hardness. That is, D21 <D23 <D22 holds. A configuration in which there is a gap at the center and there is no gap at the end will be described below as a type δ.

In any of the heating rollers of types α to δ described above, the central portion 51 has a third hardness smaller than the fourth hardness of the end portions 52 and 53. Note that the third hardness is within a range where a nip width of a certain level or more can be secured in order to obtain a high-quality image, depending on the hardness of the foamed rubber layer 50b itself and the volume of the gap formed between the metal conductive layer 50c. Change.
Further, in the case of the tight fit, the fourth hardness is such that the end foam rubber layers 52b and 53b are compressed into the metal conductive layer 50c that restricts from the outside, and a predetermined pressure is applied to the metal conductive layer 50c from the inside. It varies depending on the volume of the interference 54. The interference 54 is represented by a radial size compressed by fitting.

  In the present embodiment, as shown in Table 1, samples 1 to 3 are prepared as foamed rubber layers, and the type E durometer defined by the hardness test method for vulcanized rubber and thermoplastic rubber of JIS 6253-1997 is used. The hardness of both ends and the center of the heating roller was measured. The metal conductive layers all have an inner diameter of 45 mm, and the core rod has an outer diameter of 30 mm.

  Sample 1 is type β, and the foamed rubber layer 50b is formed such that the outer diameter D21 at the center is 45.0 mm and the outer diameter D22 at the end is 46.0 mm. The end foamed rubber layers 52b and 53b are fitted with the metal conductive layer 50c with an interference of 0.5 mm.

  Sample 2 is of type δ, and the foamed rubber layer 50b is formed such that the outer diameter D21 at the center is 43.4 mm and the outer diameter D22 at the end is 45.0 mm. The central foamed rubber layer 51b is loosely fitted to the metal conductive layer with a gap of 0.8 mm.

  Sample 3 is of type α, and the foamed rubber layer 50b is formed such that the outer diameter D21 at the center is 44.4 mm and the outer diameter D22 at the end is 45.3 mm. That is, the central foamed rubber layer 51b is tightly fitted to the metal conductive layer with a gap of 0.3 mm, and the end foamed rubber layers 52b and 53b are fitted to the metal conductive layer 50c with an interference of 0.15 mm.

  Sample 4 is of type α, and the foamed rubber layer 50b is formed such that the outer diameter D21 at the center is 44.0 mm and the outer diameter D22 at the end is 45.3 mm. That is, the central foamed rubber layer 51b is tightly fitted with the metal conductive layer with a gap of 0.5 mm, and the end foamed rubber layers 52b and 53b are fitted with the metal conductive layer 50c with an interference of 0.15 mm.

Table 1 shows that Samples 1 to 4 are not provided with pressure by a pressure roller, and are not provided with heat by a heating mechanism. A, hardness B of the central portion 51, and hardness C of the end portion 53 are shown. In addition, hardness AC is an average value of several points (here 4 points) of the circumferential direction of the foamed rubber layer which has a uniform outer diameter.

  FIG. 21 summarizes the measurement results, where the vertical axis indicates the hardness Ye of the type E durometer, and the horizontal axis indicates the radial difference Xe = (D23−D21) between the metal conductive layer and the foamed rubber layer. / 2 is shown. On the horizontal axis, “0” indicates a state in which there is no gap between the metal conductive layer and the foamed rubber layer, and a “plus” region indicates a clearance fit state in which a gap is generated between the two. The “minus” region indicates a tight fit between the two.

  Thus, when the inner diameter D23 of the metal conductive layer and the outer diameter D20 of the core rod are the same, by changing the outer diameter D21 at the center of the foamed rubber layer and the outer diameter D22 at the end within a predetermined range, The hardness of the heating roller can be changed. Further, in the case of an interference fit, the heating roller has a predetermined hardness in accordance with the size of the interference, and in the case of a clearance fit, depending on the size of the gap. That is, in any of the heating rollers of types α to δ, a predetermined difference is obtained depending on the difference between the inner diameter D23 of the metal conductive layer and the outer diameter D20 of the core rod and the thickness of the foamed rubber layer disposed therebetween. It can have third and fourth hardness.

  When the inner diameter of the metal conductive layer changes, the outer diameter of the core rod is changed accordingly, and the thickness of the foamed conductive layer is made the same as that of the present embodiment. When the outer diameter D20 of the core rod is set to 25 mm when it is 40 mm, a roller having the third and fourth hardness in the above range can be realized.

  Further, the heating roller 50 includes a foamed rubber layer having an outer diameter that is maximum at both ends and gradually decreases toward the center, like the foamed rubber layers 20b and 31b to 36b described above with reference to FIG. Also good.

  The central portion 51 of the heating roller 50 may be in a range where a nip width of a certain level or more can be secured in order to obtain a high quality image. For example, as shown in FIG. 21, the outer diameter D21 is 40.8 and the inner diameter A gap of 2.1 mm may be formed between the metal conductive layer of 45.0 mm and the hardness may be E50. Moreover, both rollers may be formed in the size as corresponding in FIG. 21, and the range of hardness E50-58 may be sufficient.

(Eleventh embodiment)
Next, still another example of the heating roller will be described with reference to FIGS. 22 (a), (b), (c), and (d).
As shown in FIG. 22A, the heating roller 60 has a foam rubber layer 60b and a metal conductive layer 60c.
The foamed rubber layer 60b includes a central portion 61b having an outer diameter D24 and an end portion 62b having an outer diameter D25 larger than the outer diameter D24. In the present embodiment, the outer diameter D24 is 39.5 mm, and the outer diameter D25 is 39.7 mm.

As shown in FIG. 22B, the metal conductive layer 60c includes a central portion 63c having a length L14 in the axial direction and an end portion 64c having a length L13 in the axial direction. A plurality of air holes 65 capable of guiding the air inside the metal conductive layer 60c to the outside are formed in the end portion 64c. In the present embodiment, the vent hole 65 is preferably formed in a general circle having a diameter of 1 mm.
The end portion 64c of the metal conductive layer 60c is bonded to a part of the outer peripheral surface of the foamed rubber layer 60b disposed on the inside using, for example, a heat-resistant adhesive so as not to crush the hole of the vent hole 65. The
It is preferable that the central portion 61b of the metal conductive layer 60c and the foamed rubber layer 60b is non-bonded and a gap 66 is formed between them. The air in the gap 66 or the air in the vicinity of the metal conductive layer 60c and the foamed rubber layer 60b is guided to the outside of the vent hole 65 through the end 62b of the foamed rubber layer 60b.
Therefore, even when the metal conductive layer 60c is heated and the inner air is thermally expanded, the inner air is guided to the outside by the vent hole 65.

  Further, the length L14 of the central portion 63c of the metal conductive layer 60c is (4) a length equal to or longer than the paper passing area, and may include a paper passing area and a non-paper passing area. Further, the length L13 of the end portion 64c may be (1) a length including a range defined as a non-sheet passing region, or (3) may be determined within a range in which sufficient adhesive strength is ensured. Good. Note that the length L11 of the end portion 62b of the foamed rubber 60b is equal to or longer than the length L14, and (2) a range in which no defect occurs in image formation including a part of the sheet passing area in addition to the non-sheet passing area. May be included. Thus, it is preferable that the air holes 65 are formed outside the paper passing area so as not to cause a defect in image formation.

  For this reason, the heating roller 60 is prevented from increasing in hardness due to thermal expansion even when the metal conductive layer 60c is heated. It is possible to maintain the hardness that can secure the nip width.

  Further, the plurality of air holes 65 may be formed randomly as shown in FIG. 22B, but may be formed side by side in the radial direction, for example, as shown in FIG. As shown in FIG. 22D, the end 64c may be formed in a mesh shape. Moreover, it is preferable that at least the end 62b of the foamed rubber layer 60b is a continuous foam in which foams are connected to each other.

  In addition, although the heating roller 60 of this Embodiment demonstrated as an example what consists of a cylindrical surface which has a uniform outer peripheral surface in an axial direction as the foaming rubber layer 60b, this invention is not limited to this, For example, Any one of the foamed rubber layers 20b and 31b to 36b shown in FIGS. 18A to 18F may be provided inside the metal conductive layer 60c.

(Twelfth embodiment)
Next, still another example of the heating roller will be described with reference to FIGS. 23 (a) and 23 (b) and FIGS. 24 (a) and 24 (b).
FIG. 23A shows a schematic perspective view of the foamed rubber layer 70b.
The foamed rubber layer 70b includes an end portion 71b having an outer diameter D1 and a central portion 72b having an outer diameter D2 smaller than the outer diameter D1, and at least air holes 73 penetrating the end portion 71b and the central portion 72b in the axial direction. Have one.

FIG. 23B shows a cross-sectional view of the end portion 71b of the heating roller 70 including the foamed rubber layer 70b.
The heating roller 70 includes a metal conductive layer 70c having a uniform inner diameter D1, a foam rubber layer 70b disposed inside the metal conductive layer 70c, and a core rod 1a disposed inside the foam rubber layer 70b.
The end portion 71b is in contact with the metal conductive layer 70c, and is bonded to the entire surface or a part of the contact portion using, for example, a heat-resistant adhesive.
The central portion 72b is not bonded to the metal conductive layer 70c and preferably has a gap therebetween.

The end portion 71b has a thickness D26 that is a distance between the core rod 1a and the metal conductive layer 70c, and has a vent hole 73 in a predetermined region.
The vent hole 73 is formed outside the dividing line 74 and inside the outer diameter D2, that is, in a region having a diameter larger than the dividing line 74 and smaller than the outer diameter D2. The dividing line 74 is a line that divides the outside from which the heat from the heated metal conductive layer 70c is easily transferred and the inside from which the heat is hardly transferred from the viewpoint of explanation. For example, the outer diameter of the end 71b It is defined as a circle having a radius smaller by 50% of the thickness D26 than D1.

Thereby, the air of the foamed rubber layer 70b warmed by the metal conductive layer 70c can be efficiently discharged to the outside of the heating roller 70.
Therefore, the heating roller 70 is prevented from increasing in hardness due to thermal expansion even when the metal conductive layer 70c is heated, and at least in a paper passing region, a high-quality image is obtained. The hardness that can secure the width can be maintained.
In addition, although the heating roller 70 of this Embodiment demonstrated as an example what consists of a cylindrical surface which has a uniform outer peripheral surface in an axial direction as the foaming rubber layer 70b, this invention is not limited to this, For example, Any one of the foamed rubber layers 20b and 31b to 36b shown in FIGS. 18A to 18F may be provided inside the metal conductive layer 70c.

Next, different examples of the foamed rubber layer having vent holes penetrating in the axial direction will be described with reference to FIGS.
FIG. 24A shows a schematic perspective view of the foamed rubber layer 80b.
The foamed rubber layer 80b includes an end portion 81b having an outer diameter D1 and a central portion 82b having an outer diameter D2 smaller than the outer diameter D1, and passes through the end portion 81b and the central portion 82b in the axial direction, and the end portion 81b. And at least one vent hole 83 having a shape in which the outer peripheral surface of the central portion 82b is cut out.

FIG. 24B shows a cross-sectional view of the end 81a of the heating roller 80 including the foamed rubber layer 80b.
The heating roller 80 has a metal conductive layer 80c having a uniform inner diameter D1, a foam rubber layer 80b disposed inside the metal conductive layer 80c, and a core rod 1a disposed inside the foam rubber layer 80b.
The end portion 81b is in contact with the metal conductive layer 80c, and the whole or a part of the contact portion is bonded using, for example, a heat-resistant adhesive.
The central part 82b is not bonded to the metal conductive layer 80c, and preferably has a gap therebetween.

The end portion 81 b has a vent hole 83 formed in a region having a thickness D27 that is a distance between the core rod 1 a and the metal conductive layer 80 c and having a diameter larger than the dividing line 84. The vent hole 83 reaches the outer peripheral surfaces of the end portion 81b and the central portion 82b. The dividing line 84 is defined as a circle whose radius is smaller by a length of 50% of the thickness D27 than the outer diameter D1 of the end portion 81b.
As a result, the air in the gap formed between the metal conductive layer 80c and the central portion 82b of the foamed rubber layer 80b can be guided to the outside through the vent hole 83 more efficiently.
The vent 83 may be a simple cut.

  In addition, although the heating roller 80 of this Embodiment demonstrated as an example what consists of a cylindrical surface which has a uniform outer peripheral surface in an axial direction as the foaming rubber layer 80b, this invention is not limited to this, For example, Any one of the foamed rubber layers 20b and 31b to 36b shown in FIGS. 18A to 18F may be provided inside the metal conductive layer 70c.

(Thirteenth embodiment)
Next, still another example of the heating roller will be described with reference to FIGS.
FIG. 25A shows a schematic perspective view of the foamed rubber layer 90b.
The foamed rubber layer 90b includes an end portion 91b having an outer diameter D1 and a central portion 92b having an outer diameter D2 smaller than the outer diameter D1, passes through the end portion 91b and the central portion 92b in the axial direction, and the end portion 91b. And at least one vent hole 93 having a shape in which the outer peripheral surface and the inner peripheral surface of the foamed rubber layer 90b including the central portion 92b are cut out.

FIG. 25B shows a cross-sectional view of the end portion 91b of the heating roller 90 including the foamed rubber layer 90b.
The heating roller 90 is disposed inside the metal conductive layer 90c having a uniform inner diameter D1, the foam rubber layer 90b disposed inside the metal conductive layer 90c, and the foam rubber layer 90b, and foamed by a predetermined bonding method. It has a core rod 1a that holds the rubber layer 90b.
The end portion 91b is in contact with the metal conductive layer 90c, and the whole or a part of the contact portion is bonded using, for example, a heat-resistant adhesive.
The central portion 92b is not bonded to the metal conductive layer 90c and preferably has a gap therebetween.

The vent hole 93 has a cutout shape that reaches the outer peripheral surface from the inner peripheral surface of the foamed rubber layer 90b. In other words, the end portion 91b and the central portion 91b have a depth in the radial direction that is equal to each thickness. .
Thereby, the air in the gap formed between the metal conductive layer 90c and the central portion 92b of the foamed rubber layer 90b or the air inside the metal conductive layer 90c is more efficiently passed through the vent hole 93. Can guide outside.
Therefore, the heating roller 90 is prevented from increasing in hardness due to thermal expansion even when the metal conductive layer 90c is heated, and at least in a paper passing region, a high-quality image is obtained. The hardness that can secure the width can be maintained.

  In addition, although the heating roller 90 of this Embodiment demonstrated as an example what consists of a cylindrical surface which has a uniform outer peripheral surface in an axial direction as a foaming rubber layer 90b, this invention is not limited to this, For example, Any one of the foamed rubber layers 20b and 31b to 36b shown in FIGS. 18A to 18F may be provided inside the metal conductive layer 90c.

(Fourteenth embodiment)
Next, still another example of the heating roller will be described with reference to FIGS.
FIG. 26B shows a cross-sectional view of the center portion of the heating roller 110.
The heating roller 110 includes a metal conductive layer 110c having an inner diameter D14, a foam rubber layer 110b disposed inside the metal conductive layer 110c, and a core rod 110a disposed inside the foam rubber layer 110b.

  The core rod 110a has a hollow portion 111a and a ventilation port 112a, and has a configuration that connects the outer peripheral surface side, that is, the foamed rubber layer 110b, and the outside, that is, both ends adjacent to the ventilation port 112a. In addition, the core rod 110a may have a configuration like the core rod 800a described above with reference to FIG.

As shown in FIG. 26A, the foamed rubber layer 110b has an end portion 111b having a maximum outer diameter D14, a center portion 112b having a minimum outer diameter D15, and an outer diameter gradually decreasing in the axial direction as approaching the center. It consists of cone parts 113b and 114b, and has a plurality of vent holes 115 extending from the inner peripheral surface to the outer peripheral surface.
The end portion 111b is in contact with the metal conductive layer 110c, and is bonded to the entire surface or a part of the contact portion using, for example, a heat-resistant adhesive.
The central portion 112b is not bonded to the metal conductive layer 110c and preferably has a gap therebetween.

The vent hole 115 penetrates the foamed rubber layer 110b in the radial direction, and connects the gap (near the metal conductive layer 110c) and the outer peripheral surface of the core rod 800a. The ventilation port 111a of the core rod 800a connected to the vent hole 115 can discharge air to the outside through the hollow portion 112a.
Thereby, the air of the foamed rubber layer 110b warmed by the metal conductive layer 110c can be efficiently discharged to the outside of the heating roller 110.

The end portion 111b is formed to have an axial length L13, and the central portion 112b and the cone portions 113b and 114b are formed to have a total axial length of length L14. As described above, the length L14 is (4) longer than the sheet passing area and may include the sheet passing area and the non-sheet passing area. The length L13 is (3) sufficient adhesive strength. May be determined within a range in which is secured.
Therefore, the vent hole 115 is formed at least in the sheet passing area. In addition, the formation of the air holes 115 reduces the hardness of the central portion 112b and the cone portions 113b and 114b.

For this reason, when the predetermined size and number of air holes 115 are formed in the sheet passing area, it is possible to maintain the hardness capable of ensuring a certain nip width or more.
The core rod 110a is not limited to this, and a vent hole is formed on the surface in contact with the central portion 112b and the cone portions 113b and 114b according to the position of the vent hole 115 of the foamed rubber layer 110b, and is in contact with the end portion 111b. It may not be formed on the surface, or the entire surface may be a mesh.
Further, by forming the air holes 115 with a predetermined size or a predetermined number, the hardness of the heating roller 110 can be reduced. Further, when the foamed rubber layer 110b is made of continuous foam in which bubbles are connected and air can move, pressure is provided from the heating roller 2 and air can be discharged from the end 111b. For this reason, even if the ventilation hole and the hollow part are not formed as the core rod 110a, it can be applied.

(Fifteenth embodiment)
Next, still another example of the heating roller will be described with reference to FIGS.
FIG. 27A shows a schematic perspective view of the foamed rubber layer 120b.
The foamed rubber layer 120b has a central portion 121b having a length L12, and end portions 122b and 123b having a length L11 that are disposed at both ends of the central portion 121b. The foamed rubber layer 120b has a uniform outer diameter D28 in the axial direction. It is formed.
The foamed rubber layer 120b has at least one vent hole 123 formed in a V shape in the axial direction on the outer peripheral surface. In other words, the vent hole 124 has a linear notch that intersects the shaft at a predetermined angle symmetrically from the center in the axial direction to the end in the axial direction. That is, the air hole 124 penetrates the outer peripheral surface of the foamed rubber layer 120b in the axial direction.

FIG. 27B shows a sectional view of the heating roller 120 including the foamed rubber layer 120b.
The heating roller 120 includes a metal conductive layer 120c having a uniform inner diameter D28, a foam rubber layer 120b disposed inside the metal conductive layer 120c, and a core rod 1a disposed inside the foam rubber layer 120b.
The end portions 122b and 123b are in contact with the metal conductive layer 120c, and are bonded to the entire surface or a part of the contact portions using, for example, a heat-resistant adhesive. The central part 121b is not bonded to the metal conductive layer 120c.

When the heating roller 120 is rotated in a state where a predetermined pressure is supplied from the pressure roller 2, a V-shaped peak is formed in each of the vent holes 124 (connecting from the outside to the outside) of the foamed rubber layer 120c. It is provided so as to reach the contact position (nip) with the pressure roller 2 earliest. That is, the foamed rubber layer 120b is provided in the apparatus so as to rotate in the direction of the arrow M.
For this reason, since the transferred transfer material passes between the heating roller 120 and the pressure roller 2 so as to be pulled to both ends in the axial direction, the formation of wrinkles can be suppressed.
Further, the foamed rubber layer 120c is preferably symmetrical with respect to the center of the circle, that is, the axis, in the cross section, and the air holes 124 are even. As a result, when the material to be transferred passes between the heating roller 120 and the pressure roller 2, it is possible to prevent the occurrence of biased stress, so that the material to be transferred is moved in the direction perpendicular to the axis and further wrinkles are formed It is hard to be done.

  In this embodiment, as shown in FIG. 27 (b), a vent hole 124 having a semicircular shape in cross section and having a predetermined depth may be used. However, as shown in FIG. A notch 125 having a depth may be used, and the notch 125 may be a simple notch.

Next, a modified example of the foamed rubber layer 120b will be described with reference to FIG.
As shown in FIG. 27 (d), the foamed rubber layer 130b has a central portion 131b having a length L12, and end portions 132b and 133b having a length L11 that are disposed at both ends of the central portion 131b. The end portions 132b and 133b are formed at the outer diameter D28, and the central portion 131b is formed at the outer diameter D29 smaller than D28.
As with the foamed rubber layer 120b, vent holes 134 and 135 are formed on the outer peripheral surface of the foamed rubber layer 130b so that a V-shaped peak is on the upstream side in the rotational direction. For this reason, the vent hole 134 formed in the outer peripheral surface of the center part 131b and the vent hole 135 formed in the outer peripheral surface of the end parts 132b and 133b do not need to be continuous. When the metal conductive layer is disposed outside the foamed rubber layer 130b, the vent hole 135 can discharge the air at the center to the outside.
When the inner diameter of the metal conductive layer is D28, a gap 136 as shown in FIG. However, the present invention is not limited to this, and may be a predetermined fit as shown in FIGS. 20 (a) to 20 (e), for example.
The vent holes 134 and 135 may be either semicircular notches shown in FIGS. 27B and 27C or simple cuts.

(Sixteenth embodiment)
FIG. 28 shows still another example of the heating roller and the pressure roller shown in FIG.
As shown in FIG. 28, the heating roller 150 includes a central portion 151 having a length L12 in the axial direction, and end portions 152 and 153 having a length L11 that are disposed at both ends of the central portion 151. The center portion 151 has a fifth hardness, and the end portions 152 and 153 have a sixth hardness.

  The heating roller 150 includes a core rod 150a, a foamed rubber layer 150b, and a metal conductive layer 150c. The foamed rubber layer 150b has a central foamed rubber layer 151b corresponding to the central part 151 and an end corresponding to the end 152. It consists of a partial foamed rubber layer 152b and an end foamed rubber layer 153b corresponding to the end 153. The central foam rubber layer 151b has an outer diameter D30, the end foam rubber layers 152b and 153b have an outer diameter D31, and the core rod 150a has an outer diameter D32.

On the other hand, the pressure roller 160 includes a central portion 161 having a length L12 in the axial direction and end portions 162 and 163 that are disposed at both ends of the central portion 161 and have a length L11. The central portion 151 has a seventh hardness greater than the fifth hardness, and the end portions 152 and 153 have an eighth hardness greater than the sixth hardness.
The pressure roller 160 includes a core rod 160a, a foam rubber layer 160b, and a metal conductive layer 160c. The foam rubber layer 160b has a central foam rubber layer 161b corresponding to the central portion 161 and an end corresponding to the end portion 162. It consists of a partial foamed rubber layer 162b and an end foamed rubber layer 163b corresponding to the end 163. The central foam rubber layer 161b has an outer diameter D33, the end foam rubber layers 162b and 163b have an outer diameter D34, and the core rod 160a has an outer diameter D35.

  The heating roller 150 and the pressure roller 160 are disposed so that the center portion and the end portion thereof face each other, and the pressure roller 160 provides a predetermined pressure to the heating roller 150. At this time, the central portion 151 of the heating roller 150 is softer (has a lower hardness) than the central portion 161 of the pressure roller 160, so that the central portion 151 changes more greatly than the pressure roller 160.

Then, as shown in FIG. 28B showing a cross section of the nip portion of the heating roller 150 and the pressure roller 160 as viewed from the axial direction, the nip portion of the pressure roller 160 bites into the heating roller 150, and the nip portion of the heating roller 150 Is recessed on the shaft side (inner side). If the fifth hardness of the central portion 151 of the heating roller 150 is smaller (soft), the curvature of the central portion 151 of the heating roller 150 is downstream in the conveyance direction of the paper P as shown in FIG. It changes rapidly. That is, the downstream side 154 of the central portion 151 is deformed to be convex toward the pressure roller 160 side. For this reason, the toner melted in contact with the surface of the heating roller 150 is easily peeled off.
Therefore, the present embodiment is used in an image forming apparatus capable of forming a color image with a larger amount of toner, and since the amount of toner is large, the problem that the heating roller and the paper are in close contact with each other and difficult to peel off can be solved.

Next, an example of the heating roller 150 having fifth and sixth hardness and the pressure roller 160 having seventh and eighth hardness will be described.
The heating roller 150 is formed to have a size equivalent to that of the sample 2 described in the tenth embodiment, and the pressure roller 160 is formed to have a size equivalent to that of the sample 1. That is, the outer diameters of the metal conductive layers 150c and 160c are 45.0 mm, the outer diameters D32 and D35 of the core rods 150a and 160a are 30.0 mm, and the outer diameter D30 of the central foamed rubber layer 151b of the heating roller is 43. The outer diameter D31 of the end foam rubber layers 152b and 153b is 45.0 mm, the outer diameter D33 of the central foam rubber layer 161b of the pressure roller is 45.0 mm, and the outer diameters of the end foam rubber layers 162b and 163b. D34 is formed at 46.0 mm, respectively. Note that the pressure roller 160 may be one of the samples 3 and 4. In other words, as described in the tenth embodiment, a predetermined hardness can be formed.

  Therefore, the fifth hardness is E58, the sixth and seventh hardness is E63, and the eighth hardness is E66. The fifth hardness <the seventh hardness, the sixth hardness <the eighth. The hardness of each holds.

  Note that the present embodiment may be configured so that at least one of the fifth hardness <the seventh hardness and the sixth hardness <the eighth hardness is satisfied, and as shown in FIG. A configuration in which the hardness is changed by using foam rubber layers at the center and end portions having different outer diameters, a configuration in which the hardness of the foam rubber layer shown in FIGS. 4 and 5 is changed, or a configuration shown in FIG. A roller having a configuration for changing the hardness of the metal conductive layer may be used as at least one of a heating roller and a pressure roller.

(Seventeenth embodiment)
FIGS. 29A to 29C show an example further different from the heating roller shown in FIG.
As shown in FIG. 29 (a), a central part 171 having a length L12 in the axial direction and end parts 172 and 173 having a length L11 are provided at both ends of the central part 171. Further, the heating roller 170 includes a metal conductive layer 170c having a uniform inner diameter, and a foam rubber layer 170b having an outer diameter that is slightly smaller than or equal to the inner diameter of the metal conductive layer 170c in the axial direction. The ends 172 and 173 are connected by an adhesive.

  As shown in FIG. 29B, the end portions 172 and 173 have an adhesive portion 174 where an adhesive is disposed, and an axial non-adhesive portion 175 that connects the central portion 171 and the outside. Thereby, the air in the central portion 171 warmed by the temperature rise of the heating roller is discharged to the outside through the non-adhesive portion 175. Therefore, it can prevent that the center part 171 becomes hard by air expansion.

  Further, as shown in FIG. 29C, the end portions 172 and 173 may further be formed with a non-adhesive portion 176 through which the adhesive portion 174 passes in the circumferential direction of the roller. Thereby, the discharge of air from the central portion 171 can be performed smoothly.

1 is a schematic diagram illustrating an example of a fixing device according to the present invention. FIG. 3 is a diagram illustrating an example of a roller that can be used in the fixing device illustrated in FIG. 1. FIG. 3 is a diagram illustrating an example of a roller that can be used in the fixing device illustrated in FIG. 1. FIG. 3 is a diagram for explaining different examples of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. The figure explaining an example of the edge part of the foamed rubber layer shown in FIG. The figure explaining the other example of the edge part of the foamed rubber layer shown in FIG. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. The figure explaining an example of the sleeve shown in FIG. The figure explaining the example from which the sleeve shown in FIG. 5 differs. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. The figure explaining an example of the core rod shown in FIG. FIG. 15 illustrates an example of a metal conductive layer illustrated in FIG. 14. FIG. 15 illustrates an example of a metal conductive layer illustrated in FIG. 14. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 2 is a diagram for explaining a relationship between a roller and hardness that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1. FIG. 5 is a diagram for explaining still another example of rollers that can be used in the fixing device shown in FIG. 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Heating roller, 2 ... Pressure roller, 1a ... Core rod, 1b ... Foam rubber layer, 1c ... Metal conductive layer.

Claims (6)

A cylindrical metal layer including a first region formed at both ends in the axial direction and a second region formed at the center in the axial direction, and a first outer diameter larger than the inner diameter of the metal layer and a foam layer with a central portion disposed inside the unrealized pre Symbol metal layer having an inner diameter and the first outer diameter smaller than the second outer diameter of the end portion of the metal layer having the foamed layer It said end portion is fixed to said first region of said metal layer, and Carlo over La gap is formed between the second region of the metal layer and the central portion of the foam layer of,
A heating mechanism provided outside the roller for exciting the metal layer;
Ru equipped with a fixing device. Before SL end fixing device according to claim 1, characterized in that it is fixed to the front Symbol first region before Symbol metal layer by using a heat-resistant adhesive. The end of the metal layer has a first hardness;
The fixing device according to claim 1, wherein the central portion of the metal layer has a second hardness smaller than the first hardness. The fixing device according to claim 1, wherein the end portion and the central portion of the metal layer are independently configured. A cylindrical metal layer including a first region formed at both ends in the axial direction and a second region formed at the center in the axial direction and having a constant inner diameter and outer diameter in the axial direction; has the outer diameter smaller than the inner diameter of the layer, a foaming layer disposed inside the metal layer, has a larger outer diameter than the inner diameter of the metal layer, fixed to the first region of the metal layer together with the said fixed member a foam layer located between the first region mutually the metal layer, the gap between the said fixing member and said second region of said metal layer and said foam layer is formed Roller ,
A heating mechanism provided outside the roller for exciting the metal layer;
Ru equipped with a fixing device.   The fixing device according to claim 5, wherein the fixing member has a vent hole that guides air in the gap to the outside of the gap.

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