Fixing device and image forming apparatus

Abstract

Provided are a method for manufacturing a heat roller, a heat roller, a fixing device, and an image forming apparatus. The method for manufacturing a heat roller includes the steps of: heating a base material made of metal in a state where a polyether ether ketone resin that is electrically insulating and thermally contractible is coated on a surface of the base material, forming an insulating portion on the surface of the base material; and forming a heat generating portion that generates heat when electricity is passed therethrough on a surface of the insulating portion.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing a heating roller, a heating roller, a fixing device, and an image forming device. Background Technology

[0002] In image forming apparatuses, regarding fixing devices for fixing unfixed developer transferred onto a medium, the following two patent publications disclose the technology.

[0003] Japanese Patent Application Publication No. 10-3226 (“0022”-“0025”) Figure 2 The heating roller 10 described in the document is as follows: an insulating film material 14 made of polyimide resin is disposed on the inner surface of the roller body 11, and a heating element 15 is disposed further inside the insulating film material 14.

[0004] Japanese Patent Application Publication Nos. 2001-201970 (“0017”-“0021”) Figure 1 The document describes a heating fixing roller 10 as follows: an insulating layer 2 made of a waterproof resin such as fluororesin is formed on the inner circumferential surface of a cylindrical mandrel 1, and a resistance heating element 3 is formed further inward from the inner circumference of the insulating layer 2. This is described in Japanese Patent Application Publication Nos. 2001-201970 (“0017”-“0021”). Figure 1 In the mold, a colorant adhesion prevention layer 4, made of a waterproof resin such as fluororesin, is also formed on the outer periphery of the core mold 1 as a release layer. Summary of the Invention

[0005] The technical challenge of this disclosure is to improve the uniformity of film thickness compared to powder coating.

[0006] According to a first aspect of this disclosure, a method for manufacturing a heating roller is provided, comprising the following steps: heating a substrate made of metal with an electrically insulating and heat-shrinkable polyether ether ketone resin covering the surface of the substrate to form an insulating portion on the surface of the substrate; and forming a heating portion on the surface of the insulating portion that generates heat when energized.

[0007] According to the second aspect of this disclosure, the manufacturing method of the heating roller uses a tubular polyetheretherketone resin.

[0008] According to the third aspect of this disclosure, the thermal shrinkage rate of the polyetheretherketone resin cylinder in the longitudinal direction is formed to be smaller than the thermal shrinkage rate in the radial direction of the cylinder.

[0009] According to a fourth aspect of this disclosure, a heating roller is provided, comprising: a substrate made of metal; a heating element made of a material that heats up when energized; and an insulating element disposed between the substrate and the heating element to electrically insulate the substrate from the heating element. The insulating element is cylindrical and is formed by a polyetheretherketone resin fixed to the outer surface of the substrate by heat shrinkage.

[0010] According to a fifth aspect of this disclosure, a fixing apparatus is provided, comprising: a heating unit having a heating roller as described in claim 4; and a pressurizing unit disposed opposite to the heating unit, such that a developer passing through a medium between the heating unit and the pressurizing unit is fixed.

[0011] According to a sixth aspect of this disclosure, the heating unit further comprises an endless strip unit that passes through a region opposite to the pressurizing unit. The strip unit is supported and heated by the heating roller, and the medium having the developer to be fixed passes between the strip unit and the pressurizing unit.

[0012] According to the seventh aspect of this disclosure, the heating roller is configured opposite to the pressurizing unit.

[0013] According to an eighth aspect of this disclosure, an image forming apparatus is provided, comprising: an image holding unit; a latent image forming unit that forms a latent image on the image holding unit; a developing unit that develops the latent image of the image holding unit; a transfer unit that transfers the image of the image holding unit onto a medium; and a fixing device that fixes the image of the medium.

[0014] (Effect)

[0015] According to the first, fourth, fifth, and eighth schemes, the uniformity of film thickness can be improved compared with the case of powder coating.

[0016] According to the second scheme, compared with the case of not using tubular PEEK resin, it is possible to form a seamless insulating part with uniform film thickness.

[0017] According to the third scheme, compared with the case where the thermal shrinkage rate in the length direction is greater than the thermal shrinkage rate in the radial direction, wrinkles on the surface of the insulation part can be suppressed.

[0018] According to the sixth scheme, the heating roller can be used to heat the belt unit, so that the developer is fixed between the belt unit and the pressure unit.

[0019] According to the seventh scheme, the developer can be fixed between the heating roller and the pressure unit. Attached Figure Description

[0020] Figure 1This is an overall explanatory diagram of the image forming apparatus according to Embodiment 1 of this disclosure.

[0021] Figure 2 This is a schematic diagram illustrating the heating roller of Example 1.

[0022] Figure 3 This is a cross-sectional view of the main part of the heating roller in Example 1.

[0023] Figure 4 This is an explanatory diagram of the manufacturing method of the heating roller in Example 1. Figure 4 (A) is an illustration of the state of the substrate before it is coated with PEEK resin. Figure 4 (B) is from Figure 4 The diagram illustrates the state of (A) where PEEK resin is applied to the substrate. Figure 4 (C) is from Figure 4 The diagram illustrates the state of PEEK resin after heat shrinkage, as shown in state (B). Figure 4 (D) is from Figure 4 An explanatory diagram showing the state in which the heating element is fixed onto PEEK resin in state (C).

[0024] Figure 5 This is an explanatory diagram of the image forming apparatus of Embodiment 2, which is the same as that of Embodiment 1. Figure 1 The corresponding diagram. Detailed Implementation

[0025] Next, specific embodiments of the present disclosure will be described with reference to the accompanying drawings, but the present disclosure is not limited to the following embodiments.

[0026] In addition, for ease of understanding of the following explanations, in the attached diagram, the front-back direction is set as the X-axis direction, the left-right direction is set as the Y-axis direction, and the up-down direction is set as the Z-axis direction. The directions or sides indicated by the arrows X, -X, Y, -Y, Z, and -Z are respectively set as front, back, right, left, top, bottom, or front side, back side, right side, left side, top side, and bottom side.

[0027] Additionally, in the diagram, the symbol “○” indicates that… The symbol “○” indicates an arrow pointing from the back of the paper to the front, while the symbol “×” indicates an arrow pointing from the front of the paper to the back.

[0028] Furthermore, in the following description using the accompanying drawings, for ease of understanding, illustrations other than those of necessary components have been appropriately omitted.

[0029] [Example 1]

[0030] Figure 1 This is an overall explanatory diagram of the image forming apparatus according to Embodiment 1 of this disclosure.

[0031] exist Figure 1 In this example, a copier U, which is an image forming apparatus, has an operation unit UI, a scanning device U1, which is an image reading device, a paper feeding device U2, a printing unit U3, which is an image recording device, and a paper ejection unit U4.

[0032] The operation unit UI includes, for example, a power button, a copy start button, a copy number setting button, number keys, and a display unit.

[0033] The scanning device U1 reads the original document (not shown) and converts it into image information, which is then input to the printing unit U3.

[0034] The paper feeding device U2 has multiple paper feeding trays TR1 to TR4, which serve as an example of a paper feeding unit. Each paper feeding tray TR1 to TR4 holds a recording sheet S, which serves as an example of a medium. A paper feeding path SH1, which serves as an example of a medium transport path, extends from each paper feeding tray TR1 to TR4 toward the printing unit U3.

[0035] exist Figure 1 In this printer, the printing unit U3 includes a control unit C and a power supply circuit E controlled by the control unit C and supplying power to each component of the printing unit U3. The control unit C receives image information of the original document read by the scanning device U1 and image information sent from a personal computer (not shown), which is an example of an information transmission device connected to the copier U.

[0036] The control unit C processes the received image information into printing information (Y: yellow, M: magenta, C: cyan, K: black) and outputs it to a laser drive circuit D, which is an example of a drive circuit for a latent image writing device. The laser drive circuit D outputs the laser drive signal input from the control unit C to exposure devices ROSy, ROSm, ROSc, and ROSk, which are examples of latent image forming units for each color, at a preset time.

[0037] Below each exposure unit ROSy to ROSk, image holding units Uy, Uc, and Uk of Y, M, C, and K are arranged.

[0038] exist Figure 1 In the example, K: the black image holding unit Uk includes a photosensitive drum Pk as an example of an image holding unit, a charged corona tube CCk as an example of a charging unit, and a photosensitive cleaner CLk as an example of a cleaning unit for the image holding unit. Furthermore, image holding units Uy, Um, and Uc of other colors Y, M, and C also have photosensitive drums Py, Pm, and Pc, charged corona tubes CCy, CCm, and CCc, and photosensitive cleaners CLy, CLm, and CLc.

[0039] In addition, in Example 1, the K-colored photosensitive drum Pk, which is used frequently and has a lot of surface wear, has a larger diameter than the photosensitive drums Py, Pm, and Pc of other colors, enabling high-speed rotation and long lifespan.

[0040] After photosensitive drums Py, Pm, Pc, and Pk are uniformly charged by charged corona tubes CCy, CCm, CCc, and CCk, respectively, electrostatic latent images are formed on the surfaces of photosensitive drums Py to Pk by laser beams Ly, Lm, Lc, and Lk, which are examples of latent image writing lights output from exposure devices ROSy, ROSm, ROSSc, and ROSk. The electrostatic latent images on the surfaces of photosensitive drums Py, Pm, Pc, and Pk are developed into toner images of various colors—Y (yellow), M (magenta), C (cyan), and K (black)—by developing rollers R0, which are examples of developing units.

[0041] The toner images on the surfaces of the photosensitive drums Py, Pm, Pc, and Pk are sequentially transferred, overlapping, to the intermediate transfer belt B (an image retention unit) in the primary transfer area Q3 via primary transfer rollers T1y, T1m, T1c, and T1k (an intermediate transfer unit). Multiple color images, or so-called color images, are formed on the intermediate transfer belt B. The color images formed on the intermediate transfer belt B are then transferred to the secondary transfer area Q4.

[0042] In addition, in the case of only black image data, only the black photosensitive drum Pk and the developing device Gk are used to form only a black toner image.

[0043] After one transfer, the residual toner remaining on the surfaces of the photosensitive drums Py, Pm, Pc, and Pk is cleaned by the photosensitive cleaners CLy, CLm, CLc, and CLk.

[0044] The image holding units Uy, Um, Uc, Uk and the developing devices Gy, Gm, Gc, Gk constitute a toner image forming component Uy+Gy, Um+Gm, Uc+Gc, Uk+Gk, which is an example of a visible image forming unit.

[0045] A toner dispenser U3a, serving as a replenishment unit, is disposed on the upper part of the printing unit U3. Toner cartridges Ky, Km, Kc, and Kk, serving as developer storage units, are detachably mounted on the toner dispenser U3a. When toner is consumed in the developing units Gy to Gk during image formation, toner is supplied from each toner cartridge Ky to Kk to each developing unit Gy to Gk.

[0046] The intermediate transfer belt B, positioned below the photosensitive drums Py to Pk, is tensioned by an intermediate drive roller Rd (an example of a drive unit for the intermediate transfer unit), an intermediate tension roller Rt (an example of a tension application unit for applying tension to the intermediate transfer belt B), an intermediate deflection roller Rw (an example of a first offset correction unit for correcting the offset and serpentine movement of the intermediate transfer belt B), multiple intermediate idle rollers Rf (an example of a driven unit), and a support roller T2a (an example of a relative unit for the secondary transfer area). The intermediate transfer belt B is then rotatably supported in the direction of arrow Ya by being driven by the intermediate drive roller Rd.

[0047] As an example of an intermediate transfer device, the belt module BM consists of the intermediate drive roller Rd, intermediate tension roller Rt, intermediate steering roller Rw, intermediate idle roller Rf, support roller T2a, primary transfer rollers T1y to T1k, and intermediate transfer belt B. Furthermore, the belt module BM in Embodiment 1 is composed of a unit that can be attached to, detached from, and replaced relative to the printing unit U3.

[0048] A secondary transfer unit Ut, serving as an example of a transfer conveying unit, is disposed below the support roller T2a. The secondary transfer unit Ut includes a secondary transfer roller T2b, serving as an example of a transfer component. The secondary transfer roller T2b is disposed opposite to the support roller T2a. The area of ​​the secondary transfer roller T2b opposite to the intermediate transfer belt B constitutes the secondary transfer area Q4. Furthermore, a contact roller T2c, serving as an example of a voltage application contact unit, contacts the support roller T2a. At a predetermined time from the power circuit E controlled by the control unit C, a secondary transfer voltage of the same polarity as the toner's charge polarity is applied to the contact roller T2c.

[0049] The rollers T2a to T2c constitute a secondary transfer unit, as an example. Alternatively, an intermediate transfer belt B, primary transfer rollers T1y to T1k, and the secondary transfer unit T2 constitute a transfer device B+T1+T2, as an example of a transfer unit.

[0050] A paper transport path SH2 is arranged below the belt module BM. Recording paper S supplied from the paper supply path SH1 of the paper supply device U2 is transported to the paper transport path SH2 via a transport roller Ra, which serves as a transport unit. The recording paper S on the paper transport path SH2 is fed out via a registration roller Rr, which serves as a delivery unit, in conjunction with the toner image being transported to the secondary transfer area Q4. It is guided by paper guides SG1 and SG2, which serve as media guide units, and is thus transported to the secondary transfer area Q4.

[0051] The toner image on the intermediate transfer belt B is transferred to the recording paper S by the secondary transfer unit T2 when passing through the secondary transfer area Q4. Additionally, in the case of a color image, the toner image that has undergone a first transfer overlapping with the surface of the intermediate transfer belt B is also transferred a second time to the recording paper S.

[0052] The intermediate transfer belt B after the secondary transfer is cleaned by a belt cleaner CLB, which is an example of a cleaning unit of the intermediate transfer unit.

[0053] The recording paper S, on which the toner image has been transferred twice, is conveyed to a media conveyor belt BH, which is an example of a conveying unit. The media conveyor belt BH conveys the recording paper S to the fixing device F. The fixing device F, which is an example of a fixing unit, includes a heating unit Fh, which is an example of a heating unit, and a pressure roller Fp, which is an example of a pressure unit. The fixing area Q5 is formed by the area where the heating unit Fh and the pressure roller Fp are opposite and in contact.

[0054] The toner image on the recording paper S is heated and fixed by the fixing device F as it passes through the fixing area Q5. The recording paper S with the toner image fixed by the fixing device F is discharged into the discharge tray TRh, which is an example of a discharge section.

[0055] The paper transport path SH is constituted by the symbols SH1, SH2, etc. Furthermore, the paper transport device SU is constituted by the symbols SH, Ra, Rr, SG1, SG2, BH, etc.

[0056] (Explanation of the fixing device)

[0057] exist Figure 1 In Embodiment 1, the heating unit Fh of the fixing apparatus F has an endless fixing belt 1, as an example of a belt-shaped unit. The fixing belt 1 of Embodiment 1 is supported by a heating roller 2 (an example of a heating element), a drive roller 3 (an example of a drive unit), and a fixing pad 4 (an example of a counter unit). The heating roller 2 heats the fixing belt 1 during image formation. The drive roller 3 rotates the fixing belt 1 during image formation. The fixing pad 4 positions the fixing belt 1 opposite the pressure roller Fp in the fixing region Q5.

[0058] (Instructions for the heating roller)

[0059] Figure 2 This is a schematic diagram illustrating the heating roller of Example 1.

[0060] Figure 3 This is a cross-sectional view of the main part of the heating roller in Example 1.

[0061] exist Figure 2 , Figure 3In Example 1, the heating roller 2 has a core mold 11 as an example of a substrate. The core mold 11 of Example 1 is made of a conductive metallic material. As an example, the core mold 11 is preferably made of aluminum, but conductive alloys such as iron or stainless steel can also be used. In addition, the core mold 11 of Example 1 is formed into a cylindrical shape extending along the rotation axis direction.

[0062] An insulating layer 12, serving as an insulating part, is formed on the outer periphery of the core mold 11. The insulating layer 12 in Example 1 is an electrically insulating material, and as an example of a material with a lower water absorption rate and moisture content than polyimide resin, it is composed of polyetheretherketone (PEEK) resin. Furthermore, the water absorption rate is measured by immersing the test piece in water at 23°C for 24 hours, as specified in JIS K 7209. As an example, the water absorption rate is 0.04% for PEEK resin, 0.8% for polyimide resin, approximately 0.4% for polyamide resin, approximately 0.3% for polyamide-imide resin, and 0.01% for PFA (perfluoroalkoxyalkylene resin), an example of a fluoropolymer resin.

[0063] A heating layer 13, serving as an example of a heating element, is formed on the outer surface of the insulating layer 12. The heating layer 13 is composed of a resistive heating element that heats up when energized. Furthermore, resistive heating elements are described in, for example, Patent Documents 1 and 2, and are therefore known prior art; detailed descriptions are omitted here.

[0064] A surface layer 14, which serves as an outer layer, is formed on the outer surface side of the heating layer 13.

[0065] In Example 1, the surface layer 14 is preferably made of an insulating material. If the surface layer 14 is made of a conductive material, current can easily flow from the heating layer 13, requiring an increase in the power supply capacity of the power supply circuit E, or there may be problems such as leakage to the fixing tape 1. Therefore, the surface layer 14 is preferably made of an electrically insulating material. As an example of an electrically insulating material, polyimide resin, glass resin, PEEK resin, fluororesin, polyamide resin, polyimide amide resin, PEKK (polyether ketone ketone) resin, etc., can be used.

[0066] Furthermore, the surface layer 14 of Example 1 is preferably made of an abrasion-resistant material to correspond to contact and wear with the fixing belt 1. Examples of abrasion-resistant materials include polyimide resin, glass resin, PEEK resin, and fluoropolymer resin.

[0067] Furthermore, from the viewpoint of heat transfer efficiency to the fixing belt 1, the surface layer 14 of Embodiment 1 is preferably lower than the insulating layer 12 (thermal resistance = (thermal conductivity) × (thickness)). That is, since the one with lower thermal resistance between the insulating layer 12 sandwiching the heating layer 13 and the surface layer 14 conducts heat more easily, it is preferable that the surface layer 14 on the fixing belt 1 side has lower thermal resistance. Therefore, when the surface layer 14 is made of the same PEEK resin as the insulating layer 12, the thickness of the surface layer 14 is thinner than the thickness of the insulating layer 12, thereby reducing thermal resistance, which is therefore preferable.

[0068] exist Figure 2 In this embodiment, the length of the heating roller 2 in the rotational axis direction is set such that the length L1 of the core mold 11 is the longest, and the lengths L2 of the insulating layer 12, L3 of the heating layer 13, and L4 of the surface layer 14 satisfy L1 > L2 > L3 ≥ L4. Furthermore, silver paste 16 for power supply is applied to both ends of the heating layer 13 in the axial direction.

[0069] (Explanation of the manufacturing method of the heating roller)

[0070] Figure 4 This is an explanatory diagram of the manufacturing method of the heating roller in Example 1. Figure 4 (A) is an illustration of the state of the substrate before it is coated with PEEK resin. Figure 4 (B) is from Figure 4 The diagram illustrates the state of (A) where PEEK resin is applied to the substrate. Figure 4 (C) is from Figure 4 The diagram illustrates the state of PEEK resin under heat shrinkage, as shown in state (B). Figure 4 (D) is from Figure 4 The diagram illustrates the state in which the heating element is fixed to the PEEK resin in state (C).

[0071] exist Figure 4 In the case of manufacturing the heating roller 2 of Embodiment 1, such as Figure 4 As shown in (A), a cylindrical body 21 made of PEEK resin with an inner diameter larger than the outer diameter of the mandrel 11 is prepared. The cylindrical body 21 is formed by extrusion molding of block-shaped PEEK resin at a high temperature of 200°C or higher. At this time, during the formation from the block state to the cylindrical state, expansion occurs during cooling, thereby solidifying into a cylindrical state with residual stress and residual strain remaining. If the cylindrical body 21 with residual strain is reheated, it will shrink, but it is preferable to form it in a manner where the radial shrinkage rate of the cylindrical body 21 is greater than the longitudinal (axial) shrinkage rate of the cylindrical body 21. In addition, from the viewpoint of ensuring insulation, the wall thickness of the cylindrical body 21 is preferably about 10 μm to 50 μm, and more preferably about 30 μm.

[0072] exist Figure 4 In (B), after setting the cylinder 21 to cover the core mold 11, the cylinder 21 and the core mold 11 are heated to above 160°C. When the core mold 11 and the cylinder 21 are heated, the cylinder 21 thermally shrinks and is tightly fixed to the core mold 11, as shown below. Figure 4 As shown in (C), an insulating layer 12 is formed.

[0073] Then, in Figure 4 (C) Figure 4 In (D), a heating layer 13 is fixed to the outer periphery of the insulating layer 12. Furthermore, when a surface layer 14 is provided, the surface layer 14 is formed by heat shrinkage, coating, etc., of the same cylinder as the insulating layer 12, and the heating roller 2 is manufactured.

[0074] (The function of Example 1)

[0075] In the copier U of Embodiment 1, which has the above-described structure, when the image forming operation begins, the heating layer 13 is energized, the heating layer 13 heats up, and the heating roller 2 heats the fixing belt 1, raising the temperature of the fixing area Q5 to a predetermined fixing temperature. Then, the recording paper S passing through the fixing area Q5 is heated, fixing the toner.

[0076] In heating rollers using the heating layer 13, sheet-like or film-like resistive heating elements as shown in Examples 1 and Patent Documents 1 and 2, an insulating layer is required to electrically insulate the resistive heating element from the core mold, as in Examples 1 and Patent Documents 1 and 2. As in the structure described in Patent Document 1, when polyimide is used as the insulating layer, the moisture in the polyimide, which has a high water absorption and moisture content, expands upon heating, causing unevenness on the surface and resulting in uneven heating and fixing. As in the structure described in Patent Document 2, using a fluoropolymer resin with low moisture content as the insulating layer can eliminate the problem of uneven fixing, but the fluoropolymer resin has high release properties. That is, even if the heating layer is to be fixed on the surface of the insulating layer, the wettability and adhesion are low, resulting in uneven adhesion of the heating layer and uneven film thickness throughout the heating roller. Therefore, if fluoropolymer resin is used as the insulating layer, the film thickness homogeneity and uniformity decrease, potentially leading to uneven fixing.

[0077] In contrast, the heating roller 2 in Example 1 uses PEEK resin as the insulating layer 12, which has high electrical insulation, low water absorption, and high wettability and adhesion to the heating layer 13, etc. Therefore, compared with the case where fluororesin is used as the insulating layer, the heating layer 13 can be uniformly fixed on the surface of the insulating layer 12. Therefore, compared with the case where fluororesin is used, film thickness uniformity can be improved and fixing unevenness can be suppressed.

[0078] Furthermore, in Embodiment 1, since the surface layer 14 is made of an insulating material, compared to the case where it is made of a conductive material, the capacity of the power supply circuit is increased, and problems such as leakage to the fixing tape 1 are suppressed.

[0079] Furthermore, in Example 1, the surface layer 14 is made of a wear-resistant material, which improves the wear resistance of the heating roller 2 that contacts the fixing belt 1 and extends its lifespan compared to the case where it is not made of a wear-resistant material.

[0080] Furthermore, in Embodiment 1, the surface layer 14 is configured to have a lower thermal resistance compared to the insulating layer 12, thereby improving the thermal conductivity of the fixing tape 1 compared to the case of high thermal resistance.

[0081] Furthermore, in Embodiment 1, the axial lengths L1 to L4 of the core mold 11, insulating layer 12, heating layer 13, and surface layer 14 are set to L1 > L2 > L3 ≥ L4. When L2 < L3, the insulation between the core mold 11 and the heating layer 13 becomes insufficient, but this situation is prevented in Embodiment 1. Additionally, when L3 < L4, it is difficult to supply power to the heating layer 13, but this situation is also prevented in Embodiment 1.

[0082] Furthermore, in Example 1, when the insulating layer 12 is formed, the cylindrical (tubular) body 21 is fixed by thermal shrinkage while covered by the mandrel 11. Currently, the coating process for producing films from PEEK material is generally powder coating. Specifically, PEEK particles with a diameter of about 10μm to 50μm are used. After spraying the PEEK particles in a dry state, sintering is performed, or a dispersion of PEEK particles is coated and then sintered, thereby forming a PEEK resin film. However, if an insulating layer 12 with a film thickness of 30μm to 50μm is made using PEEK particles with a diameter of 10μm to 50μm, unevenness remains on the surface of the insulating layer 12, making it difficult to obtain a uniform film thickness. Therefore, there is a problem that it also has an adverse effect on the film thickness of the outer heating layer 13 and surface layer 14. If the thickness of the insulating layer 12 is increased, the problem is solved. However, if the thickness is increased, the amount of PEEK material used increases, the material cost increases, and the overall heat capacity of the heating roller 2 increases, the time taken to rise to the target temperature increases, and there is also the problem of time taken until the start of the image forming operation.

[0083] In contrast, in Example 1, the cylindrical body 21, which is formed into a tube, is thermally shrunk, resulting in improved uniformity and homogeneity of film thickness compared to the case using particles. Therefore, the overall film thickness of the heating roller 2 is also more uniform and homogeneous compared to the case of powder coating, and thinner films can be formed.

[0084] Furthermore, in Example 1, the axial shrinkage rate of the cylinder 21 is smaller than the radial shrinkage rate. A higher axial shrinkage rate presents the following problem: during heat shrinkage, the axial shrinkage increases, making it easier for wrinkles to form on the surface of the insulation layer 12. In contrast, in Example 1, the radial shrinkage rate is increased, suppressing wrinkles on the surface of the insulation layer 12.

[0085] [Example 2]

[0086] Next, Embodiment 2 of the present invention will be described. In the description of Embodiment 2, the constituent elements corresponding to the constituent elements of Embodiment 1 above are marked with the same symbols, and their detailed descriptions are omitted.

[0087] This embodiment 2 differs from embodiment 1 in the following aspects, but is otherwise constructed in the same manner as embodiment 1.

[0088] Figure 5 This is an explanatory diagram of the image forming apparatus of Embodiment 2, which is the same as that of Embodiment 1. Figure 1 The corresponding diagram.

[0089] exist Figure 5 In Example 2, the heating unit Fh′ of the copier U differs from the heating unit Fh of Example 1, and is composed of a heating roller Fh′, which is an example of a heating roller. The heating roller Fh′ of Example 2, like the heating roller 2 of Example 1, has a core rod 11, an insulating layer 12, and a heating layer 13, and has a surface layer 14' that differs from the surface layer 14 of Example 1. The surface layer 14' of Example 2 uses a fluoropolymer resin with high release properties.

[0090] (The function of Example 2)

[0091] In the heating roller Fh' of Embodiment 2 having the above-described structure, PEEK resin is used in the insulating layer 12 of the heating roller Fh', which is directly opposite to the pressure roller Fp, to suppress uneven fixing. In particular, a fluoropolymer resin with good release properties is used in the surface layer 14', which is in direct contact with the unfixed toner on the surface of the recording paper S. Therefore, compared with the case where polyimide resin or the like with poor release properties compared to fluoropolymer resin is used, the toner is less likely to adhere to the surface in the heating roller Fh' of Embodiment 2. Therefore, it is possible to reduce the contamination of the surface of the heating roller Fh' by the adhered toner, and to prevent the toner on the surface of the heating roller Fh' from re-adhering to the recording paper S and contaminating the recording paper S.

[0092] (Example of Change)

[0093] The embodiments of this disclosure have been described in detail above, but this disclosure is not limited to the above embodiments, and various modifications can be made within the scope of the spirit of this disclosure as set forth in the claims. Examples of modifications of this disclosure (H01) to (H09) are illustrated below.

[0094] (H01) In the above embodiments, a photocopier is shown as an example of an image forming apparatus, but it is not limited thereto. For example, it may also be composed of a fax machine, a printer, or a multifunction printer.

[0095] (H02) In the above embodiments, an image forming apparatus using a 4-color developer is exemplified, but it is not limited to this. For example, it can also be applied to a monochrome image forming apparatus or a multicolor image forming apparatus with 3 or fewer colors or more than 5 colors.

[0096] (H03) In the above embodiment, an insulating layer 12 is disposed directly on the surface of the core mold 11, and a heating layer 13 is disposed directly on the surface of the insulating layer 12, but it is not limited to this. For example, it is also possible to have a structure in which other layers exist between the insulating layer 12 and the heating layer 13, such as in the case where a primer layer coated with a primer for improving wettability and adhesion is provided between the insulating layer 12 and the heating layer 13.

[0097] (H04) In the first embodiment, it is preferred to provide a surface layer 14, but it can also be a structure without a surface layer 14.

[0098] (H05) In the first embodiment, the surface layer 14 is preferably made of an insulating material, but it may also be made of a conductive material.

[0099] (H06) In the first embodiment, the surface layer 14 is preferably made of a wear-resistant material, but for example, it may be made of a wear-resistant material with priority on demolding properties.

[0100] (H07) In the first embodiment, a structure with low thermal resistance is preferred as the surface layer 14, but a structure with high thermal resistance can also be used.

[0101] (H08) In the above embodiments, the axial lengths L1 to L4 of each part are preferably the structures illustrated in the embodiments, but can be appropriately changed according to design, specifications, etc.

[0102] (H09) In the above embodiment, the insulating layer 12 is illustrated using a cylindrical body 21, but it is not limited to this. For example, it may be configured such that a PEEK resin film is heat-shrinked and tightly adhered while the film is wound around a mandrel. However, in the case of a wound film, seams will be formed, so it is preferable to use a cylindrical body 21.

Claims

1. A fixing device, comprising: A heating unit having an endless strip unit and a heating roller supporting and heating the strip unit; and A pressurizing unit, configured opposite to the heating unit, pressurizes the medium passing between the pressurizing unit and the strip unit. The developer passing through the medium between the heating unit and the pressurizing unit is fixed. The heating roller has: The substrate is made of metal; The resistive heating element is made of a material that heats up when energized. A first insulating portion, disposed between the substrate and the resistive heating portion, provides electrical insulation between the substrate and the resistive heating portion. This first insulating portion is formed by heat-shrinking and fixing a tubular polyetheretherketone resin to the outer surface of the substrate. The second insulating portion, which is disposed on the opposite side of the first insulating portion across the resistive heating portion, is made of a material with a lower thermal resistance than the first insulating portion. The second insulating part rotates while contacting the strip unit.

2. A fixing device, comprising: A heating unit having an endless strip unit and a heating roller supporting and heating the strip unit; and A pressurizing unit, configured opposite to the heating unit, pressurizes the medium passing between the pressurizing unit and the strip unit. The developer passing through the medium between the heating unit and the pressurizing unit is fixed. The heating roller has: The substrate is made of metal; The resistive heating element is made of a material that heats up when energized. A first insulating portion, disposed between the substrate and the resistive heating portion, provides electrical insulation between the substrate and the resistive heating portion. This first insulating portion is formed by heat-shrinking and fixing a tubular polyetheretherketone resin to the outer surface of the substrate. The second insulating portion, disposed on the opposite side of the first insulating portion across the resistive heating portion, is made of polyetheretherketone resin and is configured to have a thickness smaller than that of the first insulating portion. The second insulating part rotates while contacting the strip unit.

3. An image forming apparatus comprising: Like a holding unit; A latent image forming unit that forms a latent image on the image holding unit; The developing unit develops the latent image of the image holding unit; The transfer unit transfers the image from the image holding unit onto the medium; as well as The fixing device according to claim 1 or 2 fixes the image of the medium.

Images