Image forming device

Abstract

To maintain a contact state of a blade with a rotating body in a proper state.SOLUTION: An image forming apparatus comprises a blade 77 that is rubbed against a rotating body 2 and a heating device that heats a recording medium to be conveyed, and the heating device has a heating member 22 having heating elements 60. The heating member 22 extends in a direction Z orthogonal to a conveyance direction of the recording medium. A rubbing part 77a between the blade 77 and the rotating body 2 extends in the direction Z orthogonal to the conveyance direction of the recording medium. Both ends of the rubbing part 77a and both ends of the heating member 22 directly or indirectly face each other. The heating member 22 has a higher calorific value at one end in the direction Z orthogonal to the conveyance direction than that in a center part. The frictional force between the blade 77 and the rotating body 2 at the same one end of the rubbing part 77 as one end of the heating member 22 in the direction Z orthogonal to the conveyance direction where the calorific value is increased, is lower than the frictional force between the blade 77 and the rotating body 2 in the center part of the rubbing part 77a.SELECTED DRAWING: Figure 15

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art As image forming apparatuses such as copying machines and printers, electrophotographic image forming apparatuses that form images using toner are known.

[0003] Generally, electrophotographic image forming apparatuses are equipped with a fixing device that fixes a toner image onto paper. The fixing device includes a heating member such as a heater that heats the paper, and when the paper passes through the fixing device, the heating member heats the paper, melting the toner on the paper and fixing it to the paper.

[0004] For example, Patent Document 1 (JP 2016-62024 A) discloses a heater as a heating member provided in a fixing device, in which a heating element, electrode portions (electrical contacts), and conductive portions (conductor patterns) that electrically connect these are provided on a plate-shaped base material (substrate). Summary of the Invention [Problem to be solved by the invention]

[0005] In a heating member having such a conductive portion provided on a base material, when the heating element is made to generate heat, heat is also generated in the conductive portion due to the passage of electricity through the conductive portion. Therefore, if there is variation in the heat generation distribution of the conductive portion, this will cause variation in the temperature distribution of the heating member.

[0006] In addition, the influence of the temperature distribution variation of the heating member as described above is not limited to the fixing device having the heating member, but extends to various devices of the image forming apparatus including the peripheral devices. For example, if the influence of the temperature distribution of the heating member extends to the imaging unit that forms the image, the temperature distribution variation also occurs in the cleaning blade that cleans the surface of the photoconductor.

[0007] Here, in order for the cleaning member to perform a good cleaning function, it is required that the contact state (friction force, resilience, contact pressure, etc.) of the cleaning member with respect to the photoreceptor is in an appropriate state. However, if there is variation in the temperature distribution of the cleaning blade, there is a risk that the cleaning blade will not be able to maintain an appropriate contact state due to the influence of heat, especially in the hotter parts of the cleaning blade. In addition, such a problem is not limited to cleaning blades that clean the surface of the photoreceptor, but may also occur in blades that rub against other rotating bodies. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a printing apparatus that includes a blade that slides against a rotating body and a heating device that heats a recording medium being conveyed, the heating device having a heating member that has a heat generating body. In the image forming apparatus, the heating member extends in a direction perpendicular to a transport direction of the recording medium, a sliding portion between the blade and the rotating body extends in a direction perpendicular to the transport direction of the recording medium, and both ends of the sliding portion directly or indirectly face both ends of the heating member, The heating member has a heat generating region in which a plurality of blocks, each of which is partitioned for each heat generating element, are arranged in a direction perpendicular to the transport direction, and One end side in a direction perpendicular to the conveying direction The block located at But the center The block located at The heat generation is higher than The sliding portion directly or indirectly faces the block located on the one end side. The friction force between the blade and the rotor is The sliding portion directly or indirectly faces the block located in the central portion. The frictional force between the blade and the rotor is lower than that in the conventional rotary kiln. Effect of the Invention

[0009] According to the present invention, the contact state of the blade with the rotor can be maintained in an appropriate state. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a schematic configuration diagram of a process unit according to the embodiment. [Diagram 3] FIG. 2 is a schematic configuration diagram of a fixing device according to the present embodiment. [Figure 4] FIG. [Diagram 5] FIG. 2 is an exploded perspective view of the fixing device. [Figure 6] FIG. 2 is a perspective view of a heating unit included in the fixing device. [Figure 7] FIG. 2 is an exploded perspective view of the heating unit. [Figure 8] FIG. 2 is a plan view of the heater according to the embodiment. [Figure 9] FIG. [Figure 10] FIG. 4 is a perspective view showing a state in which a connector is connected to the heater. [Figure 11] FIG. 4 is a diagram showing a power supply structure to the heater. [Figure 12] FIG. 4 is a diagram showing variations in temperature distribution occurring in the heater. [Figure 13] FIG. 4 is a diagram showing variations in temperature distribution occurring in the heater. [Figure 14] 1A to 1C are diagrams for explaining the principle of deterioration of cleaning performance. [Figure 15] 5A and 5B are diagrams for explaining variations in temperature distribution of a cleaning blade. [Figure 16] 5A and 5B are diagrams for explaining variations in temperature distribution of a cleaning blade. [Figure 17] 11A and 11B are diagrams illustrating an example in which the free length of a cleaning blade is made different. [Figure 18] 13A and 13B are diagrams showing modified examples of the blade holding member. [Figure 19] 13A and 13B are diagrams showing other modified examples of the blade holding member. [Figure 20] 11A and 11B are diagrams illustrating an example in which the thickness of a cleaning blade is made different. [Figure 21] 11A and 11B are diagrams illustrating examples in which the cleaning blade is made of different materials. [Figure 22] 11A and 11B are diagrams illustrating an example in which the material of a part of a cleaning blade in the thickness direction is changed. [Figure 23] 11A and 11B are diagrams illustrating an example in which the lubricity of a cleaning blade with respect to a photoconductor is made different. [Figure 24] 4 is a diagram showing the positional relationship between a cleaning blade for the intermediate transfer belt and a heater provided in the fixing device; FIG. [Diagram 25] FIG. 13 is a diagram showing an example in which a cleaning blade for a secondary transfer belt is provided. [Figure 26] 13A and 13B are diagrams showing other examples of heaters in which unintended current shunting may occur. [Figure 27] FIG. 27 is a diagram showing the variation in temperature distribution occurring in the heater shown in FIG. 26. [Figure 28] FIG. 27 is a diagram showing the variation in temperature distribution occurring in the heater shown in FIG. 26. [Figure 29] FIG. 1 shows a miniaturized heater. [Diagram 30] FIG. 13 is a diagram showing another example of a miniaturized heater. [Diagram 31] 11 is a schematic configuration diagram of another fixing device to which the present invention can be applied. [Diagram 32] 11 is a schematic diagram of another fixing device to which the present invention can be applied. [Diagram 33] FIG. 13 is a schematic configuration diagram of still another fixing device to which the present invention can be applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described below with reference to the accompanying drawings. In each drawing for explaining the present invention, components such as members and components having the same function or shape are given the same reference numerals as far as they can be distinguished. Therefore, the description of components that have been described once will be omitted.

[0012] FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention.

[0013] The image forming apparatus 100 shown in FIG. 1 includes an image forming section 200 and a transfer section 300 as image forming means, a fixing section 400, a recording medium supply section 500, and a recording medium discharge section 600.

[0014] The image forming section 200 is provided with four process units 1Y, 1M, 1C, and 1Bk, and an exposure device 6. Each process unit 1Y, 1M, 1C, and 1Bk is an imaging unit that is detachable from the image forming apparatus main body. Each process unit 1Y, 1M, 1C, and 1Bk basically has the same configuration, except that it contains toner (developer) of different colors, yellow, magenta, cyan, and black, which correspond to the color separation components of a color image. Specifically, each process unit 1Y, 1M, 1C, and 1Bk includes a photoconductor 2, a charging member 3, a developing device 4, a cleaning device 5, and a lubricant supplying device 7.

[0015] The photoreceptor 2 is an image carrier that carries an image on its surface. In this embodiment, a drum-shaped photoreceptor (photoreceptor drum) is used as the photoreceptor 2. It is also possible to use a belt-shaped photoreceptor (photoreceptor belt) as the photoreceptor 2.

[0016] The charging member 3 is a member that charges the surface of the photoreceptor 2. In this embodiment, a roller-shaped charging member that contacts the surface of the photoreceptor 2 is used as the charging member 3. However, the charging member 3 is not limited to a contact type, and may be a non-contact type such as a corona charging type.

[0017] The developing device 4 is a device that supplies toner as a developer to the surface of the photoreceptor 2. For example, the developing device 4 has a developer supplying member such as a developing roller that contacts the photoreceptor 2. As the developer supplying member rotates, the developer (toner) carried on the developer supplying member is supplied to the surface of the photoreceptor 2.

[0018] The cleaning device 5 is a device that cleans the surface of the photoreceptor 2, which is a cleaning target. As shown in FIG. 2, the cleaning device 5 has a cleaning blade 77, a blade holding member 78, and a spring 79 as a blade biasing member. The cleaning blade 77 is a substantially plate-shaped member made of an elastic material such as urethane rubber, and is held at one end by the blade holding member 78. The cleaning blade 77 is held in contact with the surface of the photoreceptor 2 by the blade holding member 78 being biased by the spring 79. When the photoreceptor 2 rotates in this state, the cleaning blade 77 rubs against the rotating photoreceptor 2, and foreign matter such as residual toner on the photoreceptor 2 is removed by the cleaning blade 77.

[0019] The lubricant supplying device 7 is a device that supplies a lubricant to the surface of the photoreceptor 2. In the example shown in FIG. 2, the lubricant supplying device 7 has a lubricant 80, a brush roller 81 as a lubricant supplying member, a spring 82 as a lubricant biasing member, an application blade 83 as a thinning member, and a spring 84 as a blade biasing member. The lubricant 80 is biased to the brush roller 81 by the spring 82. In this state, the brush roller 81 rotates, so that the lubricant 80 is scraped off by the brush roller 81 and supplied to the surface of the photoreceptor 2. In addition, the application blade 83 is held in contact with the surface of the photoreceptor 2 by the spring 79. Therefore, when the lubricant is supplied to the surface of the photoreceptor 2, the lubricant is thinned to a uniform thickness when passing through the contact portion between the photoreceptor 2 and the application blade 83, and is applied to the surface of the photoreceptor 2.

[0020] As shown in FIG. 1, the transfer unit 300 is provided with a transfer device 8 that transfers an image onto a recording medium such as paper. The recording medium onto which the image is transferred may be a paper sheet such as plain paper, thick paper, thin paper, coated paper, label paper, or an envelope, or a resin sheet such as an OHP. The transfer device 8 has an intermediate transfer belt 11, a primary transfer roller 12, a secondary transfer roller 13, and a belt cleaning device 10. The intermediate transfer belt 11 is an endless belt member and is stretched by a plurality of rollers. A plurality of primary transfer rollers 12 (the same number as the number of photoconductors 2) are provided corresponding to each photoconductor 2. Each primary transfer roller 12 contacts the photoconductor 2 via the intermediate transfer belt 11, and thus a primary transfer nip is formed between the intermediate transfer belt 11 and each photoconductor 2, where the intermediate transfer belt 11 and each photoconductor 2 are in contact with each other. Meanwhile, the secondary transfer roller 13 contacts one of a plurality of rollers that stretch the intermediate transfer belt 11 via the intermediate transfer belt 11. As a result, a secondary transfer nip is formed between the intermediate transfer belt 11 and the belt cleaning device 10. The belt cleaning device 10 has a cleaning blade 69 that comes into contact with the surface of the intermediate transfer belt 11.

[0021] The fixing section 400 is provided with a fixing device 9 that fixes an image onto a sheet of paper. The detailed configuration of the fixing device 9 will be described later.

[0022] The recording medium supply unit 500 is provided with a paper feed cassette 14 that stores paper P as a recording medium, and a paper feed roller 15 that feeds the paper P from the paper feed cassette 14.

[0023] The recording medium ejection section 600 is provided with a pair of ejection rollers 17 for ejecting paper outside the image forming apparatus, and an ejection tray 18 on which the paper ejected by the ejection rollers 17 is placed.

[0024] Next, the printing operation of the image forming apparatus 100 according to this embodiment will be described with reference to FIG.

[0025] When a printing operation is started in the image forming apparatus 100, the photoconductors 2 and intermediate transfer belt 11 of the process units 1Y, 1M, 1C, and 1Bk start to rotate. Also, the paper feed roller 15 starts to rotate and feeds the paper P from the paper feed cassette 14. The fed paper P comes into contact with a pair of timing rollers 16 and is temporarily stopped.

[0026] In each process unit 1Y, 1M, 1C, 1Bk, first, the charging member 3 charges the surface of the photoconductor 2 to a uniform high potential. Next, the exposure device 6 exposes the surface (charged surface) of each photoconductor 2 based on the image information of the document read by the document reading device or the print image information instructed to be printed from the terminal. As a result, the potential of the exposed portion is reduced and an electrostatic latent image is formed on the surface of each photoconductor 2. Then, the developing device 4 supplies toner to this electrostatic latent image, and a toner image is formed on each photoconductor 2. Note that the image forming apparatus 100 according to this embodiment can form a full-color image using all the process units 1Y, 1M, 1C, 1Bk, or can form a monochromatic image using any one of the process units. Also, a two-color or three-color image can be formed using any two or three of the process units.

[0027] When the toner images formed on each photoreceptor 2 reach the primary transfer nip (the position of the primary transfer roller 12) as each photoreceptor 2 rotates, they are transferred to the rotating intermediate transfer belt 11 so as to be overlapped in sequence. Thereafter, in preparation for the next image formation, the surface of each photoreceptor 2 is cleaned by the cleaning device 5, and further, a lubricant is supplied to the surface of each photoreceptor 2 by the lubricant supplying device 7.

[0028] The toner image transferred onto the intermediate transfer belt 11 is transported to a secondary transfer nip (the position of the secondary transfer roller 13) as the intermediate transfer belt 11 rotates, and is transferred onto the paper P that has been transported by a timing roller 16. Thereafter, the surface of the intermediate transfer belt 11 is cleaned by a belt cleaning device 10 in preparation for the next image formation.

[0029] The paper P onto which the image has been transferred is transported to a fixing device 9, which fixes the toner image onto the paper P. Then, the paper P onto which the toner image has been fixed is discharged onto a paper discharge tray 18 by a paper discharge roller 17, and a series of printing operations is completed.

[0030] Next, the configuration of the fixing device 9 according to this embodiment will be described.

[0031] As shown in FIG. 3, the fixing device 9 according to this embodiment includes a fixing belt 20, a pressure roller 21, a heater 22, a heater holder 23, a stay 24, and a temperature sensor 19.

[0032] The fixing belt 20 is a rotating body (first rotating body) that is disposed on the unfixed toner carrying surface side (image forming surface side) of the paper P and functions as a fixing member that fixes the unfixed toner to the paper P. The fixing belt 20 has a substrate made of, for example, polyimide. The material of the substrate is not limited to polyimide, and may be a heat-resistant resin such as PEEK, or a metal material such as nickel or SUS. In order to increase durability and ensure releasability, a release layer made of a fluororesin such as PFA or PTFE may be provided on the outer peripheral surface of the substrate. Furthermore, an elastic layer made of rubber or the like may be provided between the substrate and the release layer. In addition, a sliding layer made of polyimide, PTFE, or the like may be provided on the inner peripheral surface of the substrate.

[0033] The pressure roller 21 is a rotating body (second rotating body) separate from the fixing belt 20, and is an opposing member disposed so as to face the outer circumferential surface of the fixing belt 20. The pressure roller 21 has a metal core, an elastic layer made of silicone rubber or the like provided on the outer circumferential surface of the core, and a release layer made of fluororesin or the like provided on the outer circumferential surface of the elastic layer.

[0034] The fixing belt 20 and the pressure roller 21 are pressed against each other by a biasing member such as a spring. As a result, a nip portion N is formed between the fixing belt 20 and the pressure roller 21. A driving force is transmitted to the pressure roller 21 from a driving source provided in the image forming apparatus main body. Therefore, when the pressure roller 21 is driven to rotate, the driving force is transmitted to the fixing belt 20 at the nip portion N, and the fixing belt 20 is rotated by the pressure roller 21. Then, as shown in FIG. 3, when a sheet P carrying an unfixed image enters between the rotating fixing belt 20 and the pressure roller 21 (nip portion N), the sheet P is heated and pressed by the fixing belt 20 and the pressure roller 21 while being transported. As a result, the unfixed image on the sheet P is fixed to the sheet P.

[0035] The heater 22 is a heating member that heats the fixing belt 20. In this embodiment, the heater 22 has a plate-shaped base material 50, a first insulating layer 51 provided on the base material 50, a conductor layer 52 provided on the first insulating layer 51, and a second insulating layer 53 that covers the conductor layer 52. The conductor layer 52 includes a resistance heating element 60 that generates heat when electricity is applied.

[0036] In this embodiment, since the resistance heating element 60 is disposed on the nip portion N side of the substrate 50, the heat of the resistance heating element 60 is transferred to the fixing belt 20 without passing through the substrate 50, and the fixing belt 20 can be efficiently heated. The resistance heating element 60 may also be disposed on the opposite side of the substrate 50 from the nip portion N side. In that case, however, since the heat of the resistance heating element 60 is transferred to the fixing belt 20 via the substrate 50, it is preferable that the substrate 50 be made of a material with high thermal conductivity, such as aluminum nitride.

[0037] In addition, in this embodiment, the heater 22 is disposed so as to be in direct contact with the inner circumferential surface of the fixing belt 20, so that the heat of the heater 22 is efficiently transferred to the fixing belt 20. The heater 22 is not limited to being in direct contact with the fixing belt 20, and may be indirectly in contact with the fixing belt 20 through a non-contact or low-friction sheet or the like. It is also possible to select the outer circumferential surface of the fixing belt 20 as the contact point of the heater 22 with the fixing belt 20. However, in this case, there is a risk that the contact between the heater 22 and the fixing belt 20 may cause scratches on the outer circumferential surface of the fixing belt 20, which may result in a deterioration in fixing quality. Therefore, it is preferable that the contact point of the heater 22 is on the inner circumferential surface of the fixing belt 20 rather than the outer circumferential surface.

[0038] The heater holder 23 is a heating member holder disposed inside the fixing belt 20 and holds the heater 22. The heater holder 23 is preferably made of a heat-resistant material because it is likely to become hot due to the heat of the heater 22. In particular, when the heater holder 23 is made of a heat-resistant resin with low thermal conductivity such as LCP or PEEK, the heat resistance of the heater holder 23 is ensured while heat transfer from the heater 22 to the heater holder 23 is suppressed, so that the fixing belt 20 can be heated efficiently.

[0039] The stay 24 is a reinforcing member disposed inside the fixing belt 20 to reinforce the heater 22 and the heater holder 23. The stay 24 supports the surface of the heater holder 23 opposite to the surface on the nip portion N side, thereby suppressing deflection of the heater holder 23 due to the pressure force of the pressure roller 21. As a result, the nip portion N of a uniform width is formed between the fixing belt 20 and the pressure roller 21. The stay 24 is preferably made of an iron-based metal material such as SUS or SECC to ensure its rigidity.

[0040] The temperature sensor 19 is a temperature detection member that detects the temperature of the heater 22. As the temperature sensor 19, a known temperature sensor such as a thermopile, a thermostat, a thermistor, or an NC sensor can be applied. The temperature sensor 19 may be a contact type temperature sensor arranged to be in contact with the heater 22, or a non-contact type temperature sensor arranged to face the heater 22 with a gap therebetween. In this embodiment, the temperature sensor 19 is arranged to be in contact with the surface of the heater 22 opposite to the nip N side.

[0041] FIG. 4 is a perspective view of the fixing device according to this embodiment, and FIG. 5 is an exploded perspective view thereof.

[0042] As shown in FIG. 4 and FIG. 5, the device frame 40 of the fixing device 9 includes a first device frame 25 and a second device frame 26. The first device frame 25 includes a pair of side walls 28 and a front wall 27. On the other hand, the second device frame 26 includes a rear wall 29. The pair of side walls 28 are disposed at one end side and the other end side in the belt longitudinal direction (the longitudinal direction of the fixing belt 20). The side walls 28 support both end sides of the fixing belt 20 and the pressure roller 21. Each side wall 28 is provided with a plurality of engagement protrusions 28a. The engagement protrusions 28a are engaged with engagement holes 29a provided in the rear wall 29, whereby the first device frame 25 and the second device frame 26 are assembled together.

[0043] Further, each side wall portion 28 is provided with an insertion groove 28b for inserting the rotating shaft of the pressure roller 21 and the like. The insertion groove 28b opens on the rear wall portion 29 side. The opposite side of the insertion groove 28b from the rear wall portion 29 side is an abutment portion that does not open. A bearing 30 that supports the rotating shaft of the pressure roller 21 is provided on the end on the abutment portion side. Both ends of the rotating shaft of the pressure roller 21 are attached to the bearings 30, so that the pressure roller 21 is rotatably supported by the both side wall portions 28.

[0044] Further, a drive transmission gear 31 is provided as a drive transmission member on one end side of the rotation shaft of the pressure roller 21. The drive transmission gear 31 is exposed outside the side wall portions 28 when the pressure roller 21 is supported by the both side wall portions 28. As a result, when the fixing device 9 is mounted on the image forming apparatus main body, the drive transmission gear 31 is connected to a gear provided on the image forming apparatus main body, and a drive force can be transmitted from the drive source to the pressure roller 21. Note that the drive transmission member that transmits the drive force to the pressure roller 21 is not limited to the drive transmission gear 31, and may be a pulley that stretches a drive transmission belt, a coupling mechanism, or the like.

[0045] A pair of support members 32 that support the fixing belt 20, the stay 24, etc. are provided on both ends of the fixing belt 20 in the longitudinal direction. The pair of support members 32 support the fixing belt 20, the heater holder 23, the stay 24, etc. Each support member 32 is provided with a guide groove 32a. The support member 32 is assembled to the side wall portion 28 by moving the guide groove 32a along the edge of the insertion groove 28b of the side wall portion 28 and inserting the support member 32 into the insertion groove 28b.

[0046] Further, a pair of springs 33 serving as urging members are provided between each of the support members 32 and the rear wall portion 29. Each of the springs 33 urges the stays 24 and the support members 32 toward the pressure roller 21, thereby pressing the fixing belt 20 against the pressure roller 21. As a result, a nip portion is formed between the fixing belt 20 and the pressure roller 21.

[0047] As shown in FIG. 5, a hole 29b is provided at one end of the rear wall 29 constituting the second device frame 26 in the longitudinal direction. The hole 29b is a positioning portion for positioning the fixing device body relative to the image forming device body. On the other hand, a protrusion 101 is provided on the image forming device body as a positioning portion. The protrusion 101 is inserted into the hole 29b of the fixing device 9, so that the protrusion 101 and the hole 29b fit together. This positions the fixing device body in the belt longitudinal direction relative to the image forming device body. Note that no positioning portion is provided on the end side opposite to the end side where the hole 29b of the rear wall 29 is provided. Therefore, even if the fixing device body expands and contracts in the belt longitudinal direction due to temperature changes, the expansion and contraction of the fixing device body is not restricted, and distortion of the fixing device body is suppressed.

[0048] FIG. 6 is a perspective view of a heating unit provided in the fixing device according to this embodiment, and FIG. 7 is an exploded perspective view of the heating unit.

[0049] As shown in Figs. 6 and 7, the heater holder 23 has a rectangular accommodating recess 23a for accommodating the heater 22 on its surface on the fixing belt side (the surface on the front side in Figs. 6 and 7). The accommodating recess 23a is formed to have substantially the same shape and size as the heater 22. However, the longitudinal dimension L2 of the accommodating recess 23a is set to be slightly longer than the longitudinal dimension L1 of the heater 22. Since the accommodating recess 23a is formed to be slightly longer than the heater 22, the heater 22 and the accommodating recess 23a do not interfere with each other even if the heater 22 expands in its longitudinal direction due to thermal expansion. In addition, when the heater 22 is accommodated in the accommodating recess 23a, the heater 22 is held by being sandwiched together with the heater holder 23 by a connector as a power supply member, which will be described later.

[0050] The pair of support members 32 has a C-shaped belt support portion 32b, a flange-shaped belt regulation portion 32c, and a support recess 32d. Each belt support portion 32b is inserted inside both ends of the fixing belt 20 in the longitudinal direction. As a result, the fixing belt 20 is supported by each belt support portion 32b in a so-called free belt manner (in a state where no tension is applied to the fixing belt 20 at least when the fixing belt 20 is not rotating). On the other hand, each belt regulation portion 32c is not inserted inside the fixing belt 20, but is arranged to face the end of the fixing belt 20 in the longitudinal direction. As a result, even if the fixing belt 20 moves in one direction in the longitudinal direction, the end of the fixing belt 20 in the longitudinal direction comes into contact with the belt regulation portion 32c, thereby regulating the movement (deviation) of the fixing belt 20. The heater holder 23 and the stay 24 are inserted into the support recess 32d near both ends in the longitudinal direction. As a result, the heater holder 23 and the stay 24 are supported by the pair of support members 32.

[0051] As shown in Fig. 6 and Fig. 7, a positioning recess 23e is provided as a positioning portion at one end side in the longitudinal direction of the heater holder 23. The fitting portion 32e of the support member 32 shown on the left side of Fig. 6 and Fig. 7 fits into this positioning recess 23e, thereby positioning the heater holder 23 and the support member 32 in the belt longitudinal direction. On the other hand, the fitting portion 32e is not provided on the support member 32 shown on the right side of Fig. 6 and Fig. 7. Therefore, the support member 32 is not positioned in the belt longitudinal direction relative to the heater holder 23 on the right side of the figures. In this way, the heater holder 23 is positioned relative to the support member 32 only on one side in the belt longitudinal direction, so that the heater holder 23 is allowed to expand and contract in the belt longitudinal direction due to temperature changes.

[0052] 7, steps 24a are provided on both ends of the stay 24 in the longitudinal direction. Each step 24a abuts against the support member 32, thereby restricting longitudinal movement of the stay 24 relative to the support member 32. However, at least one of these step parts 24a is disposed with a gap (backlash) between it and the support member 32. In this way, by disposing at least one step part 24a with a gap between it and the support member 32, expansion and contraction of the stay 24 in the belt longitudinal direction due to temperature changes is permitted.

[0053] FIG. 8 is a plan view of the heater according to this embodiment, and FIG. 9 is an exploded perspective view of the heater.

[0054] 8 and 9, the heater 22 has a plate-shaped base material 50. A first insulating layer 51, a conductor layer 52, and a second insulating layer 53 are laminated on the base material 50. The base material 50 is disposed so as to extend longitudinally in the direction of the arrow Z in FIG. 8, which is the longitudinal direction of the fixing belt 20 or the rotational axis direction of the pressure roller 21.

[0055] The substrate 50 is formed of a metal material such as stainless steel (SUS), iron, or aluminum. The material of the substrate 50 is not limited to a metal material, and may be ceramic, glass, or the like. When the substrate 50 is formed of an insulating material such as ceramic, the first insulating layer 51 between the substrate 50 and the conductor layer 52 can be omitted. On the other hand, a metal material is excellent in durability against rapid heating and is easy to process, so it is suitable for reducing the cost of the heater. Among the metal materials, aluminum or copper is particularly preferable in that it has high thermal conductivity and is less likely to cause temperature unevenness. Furthermore, the substrate 50 can be manufactured more cheaply from stainless steel than from aluminum or copper.

[0056] The first insulating layer 51 and the second insulating layer 53 are formed of an insulating material such as heat-resistant glass, ceramic, or polyimide.

[0057] The conductor layer 52 has a plurality of resistance heating elements 60, as well as a plurality of electrode portions 61 and a plurality of power supply lines (conductive portions) 62. The plurality of resistance heating elements 60 are electrically connected in parallel to any two of the three electrode portions 61 via the power supply lines 62 provided on the base material 50 in the number of hooks.

[0058] The resistance heating element 60 is formed, for example, by screen printing a paste made of a mixture of silver palladium (AgPd) and glass powder on the substrate 50, and then firing the substrate 50. As the material for the resistance heating element 60, in addition to the above-mentioned materials, a resistance material such as a silver alloy (AgPt) or ruthenium oxide (RuO2) can be used.

[0059] The electrode portion 61 and the power supply line 62 are formed of a conductor having a resistance value smaller than that of the resistance heating element 60. Specifically, the electrode portion 61 and the power supply line 62 are formed by screen printing a material such as silver (Ag) or silver-palladium (AgPd) on the base material 50.

[0060] 8, the entirety of each resistance heating element 60 and at least a part of each power supply line 62 are covered with the second insulating layer 53 to ensure insulation. On the other hand, each electrode portion 61 is a portion to which a connector is connected, and therefore is hardly covered with the second insulating layer 53 and is exposed.

[0061] FIG. 10 is a perspective view showing a state in which a connector is connected to the heater according to the present embodiment.

[0062] 10, connector 70 has a resin housing 71 and a plurality of contact terminals 72. Each contact terminal 72 is a conductive elastic member such as a leaf spring. Each contact terminal 72 is provided in housing 71. A power supply harness 73 is connected to each contact terminal 72.

[0063] As shown in FIG. 10, the connector 70 is attached so as to sandwich the heater 22 and the heater holder 23 together. As a result, the heater 22 and the heater holder 23 are held by the connector 70. The connector is also connected to the electrode portion 61 on the opposite side to each electrode portion 61 shown in FIG. 10. The tip (contact portion 72a) of each contact terminal 72 elastically contacts (pressure-welds) the corresponding electrode portion 61, thereby electrically connecting each contact terminal 72 and each electrode portion 61. As a result, the image forming apparatus is in a state in which power can be supplied to each resistance heating element 60 from a power source provided in the image forming apparatus body. In this state, when power is supplied to each resistance heating element 60 via the connector 70, each resistance heating element 60 generates heat.

[0064] As shown in FIG. 11, in this embodiment, among the multiple resistance heating elements 60 arranged in the longitudinal direction (arrow Z direction) of the base material 50, a first heating section (first resistance heating element group) 60A consisting of the resistance heating elements 60 other than those at both ends, and a second heating section (second resistance heating element group) 60B consisting of the resistance heating elements 60 at both ends can generate heat independently. Specifically, each of the resistance heating elements 60 other than those at both ends constituting the first heating section 60A is connected to a first electrode portion 61A provided at one end side in the longitudinal direction of the base material 50 via a first power supply line 62A. Also, each of the resistance heating elements 60 constituting the first heating section 60A is connected to a second electrode portion 61B provided at the end side opposite to the first electrode portion 61A side via a second power supply line 62B. On the other hand, each of the resistance heating elements 60 at both ends constituting the second heating portion 60B is connected via a third power supply line 62C or a fourth power supply line 62D to a third electrode portion 61C (different from the first electrode portion 61A) provided on one end side in the longitudinal direction of the base material 50. Moreover, each of the resistance heating elements 60 at both ends is connected to the second electrode portion 61B via a second power supply line 62, like each of the resistance heating elements 60 other than those at both ends.

[0065] Furthermore, by connecting the aforementioned connectors 70 to the respective electrodes 61A to 61C, power can be supplied from the power source 64 to each of the resistance heating elements 60. Between the first electrode portion 61A and the power source 64, and between the third electrode portion 61C and the power source 64, switches 65A and 65B serving as switching units are provided, respectively. The switching timing of these switches 65A and 65C, i.e., the timing of power supply to the heater 22, is controlled by a control circuit 66. For example, the control circuit 66 controls the switching timing of each of the switches 65A and 65C based on the detection results of various sensors such as a paper passing sensor provided in the image forming apparatus.

[0066] When a voltage is applied to the first electrode portion 61A and the second electrode portion 61B and a potential difference occurs between the two electrodes 61A and 61B, a current flows through each resistance heating element 60 other than those at both ends, and only the first heating portion 60A generates heat. On the other hand, when a voltage is applied to the second electrode portion 61B and the third electrode portion 61C and a potential difference occurs between the two electrodes 61C and 61B, a current flows through each resistance heating element 60 at both ends, and only the second heating portion 60B generates heat. When a voltage is applied to all the electrodes 61A to 61C, both (all) resistance heating elements 60 of the first heating portion 60A and the second heating portion 60B generate heat. For example, when a relatively small size paper of A4 size (paper width: 210 mm) or less is passed through, only the first heating portion 60A is heated. When a relatively large size paper of A3 size or more (paper width: 297 mm) is passed through, the second heat generating portion 60B is also made to generate heat in addition to the first heat generating portion 60A, thereby obtaining a heat generating area according to the paper width.

[0067] Generally, in a heater having a resistance heating element on a substrate as described above, when the resistance heating element generates heat, a current flows through the power supply line, which also generates a small amount of heat in the power supply line. Therefore, depending on the heat distribution in the power supply line, there is a risk that the temperature distribution of the heater will vary. In particular, if the current flowing through the resistance heating element is increased in order to increase the amount of heat generated in association with the increase in the speed of the image forming apparatus, the amount of heat generated in the power supply line will also increase, and the effect of heat generation in the power supply line cannot be ignored.

[0068] Here, the variation in temperature distribution (temperature distribution deviation) occurring in the heater according to this embodiment will be described with reference to the examples shown in FIGS.

[0069] FIG. 12 is a diagram showing the amount of heat generated in each of the power supply lines 62A, 62B, and 62D in each block divided for each of the resistance heating elements 60 and the total amount of heat generated in each block when 20% of the current flows through each of the resistance heating elements 60. The amount of heat generated shown in the table of FIG. 12 is calculated as the square of the current (I) flowing through each power supply line based on the relationship between the amount of heat generated (W) and the current (I) shown in the following formula (1). Therefore, the calculated value of the amount of heat generated is merely a simply calculated value and differs from the actual amount of heat generated. In this embodiment, the length of each of the power supply lines 62A, 62B, and 62D extending in the short-side direction of the heater 22 (arrow Y direction in FIG. 12) is shorter than the length of each of the power supply lines 62A, 62B, and 62D extending in the long-side direction of the heater 22 (arrow Z direction in FIG. 12), and the amount of heat generated in the part extending in the short-side direction is small. 12, the heat generation amount of the portion extending in the short direction of each of the power feeders 62A, 62B, 62D is ignored, and only the heat generation amount of the portion extending in the long direction of each of the power feeders 62A, 62B, 62D is calculated. Moreover, the short direction of the heater 22 means the direction (arrow Y direction) that intersects with the long direction (arrow Z direction) along the surface of the base material 50 on which the resistance heating element 60 is provided.

[0070]

number

[0071] The calculation method of the heat generation amount will be described by taking the first block and the second block in FIG. 12 as an example. For example, in the first block in FIG. 12, the current flowing through the first power feed line 62A is 100%, and the current flowing through the fourth power feed line 62D is 20%. Therefore, the total heat generation amount in the first block is 10400 (10000+400) calculated by summing up the square values ​​of the currents flowing through the power feed lines 62A and 62D. In addition, in the second block in FIG. 12, the current flowing through the first power feed line 62A is 80%, the current flowing through the second power feed line 62B is 20%, and the current flowing through the fourth power feed line 62D is 20%. Therefore, the total heat generation amount in the second block is 7200 (6400+400+400) calculated by summing up the square values ​​of the currents flowing through the power feed lines 62A, 62B, and 62D. The heat generation amounts of the other blocks are calculated in a similar manner.

[0072] The total heat generation amount of each block is plotted on the vertical axis in the graph in Fig. 12. As can be seen from this graph, in the heater 22 according to this embodiment, the total heat generation amount of each power supply line is large in the blocks at both ends (first block and seventh block) and is small in the blocks at the center (third block and fourth block). As such, the heat generation distribution of the power supply lines varies along the longitudinal direction of the heater 22, and therefore the temperature distribution of the entire heater 22 also varies.

[0073] In addition, such temperature variation caused by heat generation from the power supply line is not limited to the case where all the resistance heating elements generate heat (example shown in FIG. 12), but may occur even when some of the resistance heating elements generate heat. In particular, when unintended current shunting occurs in the power supply line due to miniaturization of the heater or high speed of the image forming apparatus, there is a risk that the temperature variation will become significant. Unintended current shunting is likely to occur when the resistance value of the power supply line increases as a result of reducing the width of the power supply line in the short direction of the heater in response to miniaturization of the heater. Unintended current shunting is also likely to occur when the resistance value of the resistance heating element is reduced in order to increase the amount of heat generated by the resistance heating element in response to high speed of the image forming apparatus. In other words, when the resistance value of the power supply line increases or the resistance value of the resistance heating element decreases, or both of them cause the resistance value of the power supply line and the resistance value of the resistance heating element to become relatively close to each other, current will flow through a path through which no current has flowed before, and unintended current shunting may occur.

[0074] For example, as shown in FIG. 13, unintended current shunting may occur when current is passed through each of the resistance heating elements 60 other than the two ends. Specifically, in this example, 20% of the current flows through each of the resistance heating elements 60 other than the two ends. However, in the second resistance heating element 60 from the left in the figure, a part of the current (5%) that has passed through flows in the opposite direction (leftward in the figure) to the second electrode portion 61B at the branch portion X of the second power supply line 62B, causing current shunting. In addition, a part of the split current passes through the resistance heating element 60 at the left end in FIG. 13, and then passes through the resistance heating element 60 at the right end via the third power supply line 62C, the third electrode portion 61C, and the fourth power supply line 62D, and then merges with the second power supply line 62B. Note that, although the current is shown to flow in one direction here, the current flowing through the heater 22 is not limited to direct current and may be alternating current.

[0075] The table and graph in Fig. 13 show the amount of heat generated in each of the power feed lines 62A, 62B, 62D for each block and the total amount of heat generated in the case where unintended shunting occurs. The method for calculating the amount of heat is the same as the method described above in the example shown in Fig. 12. For the same reason as in the example shown in Fig. 12, the amount of heat generated in the portions of the power feed lines 62A, 62B, 62D extending in the short direction (direction of arrow Y) is also omitted in the example shown in Fig. 13.

[0076] As shown in the table and graph in Fig. 13, in this case too, the total heat generation amount of the power feeder is large in the blocks at both ends (blocks 2 and 6) and is small in the block in the center (block 4), causing variation in temperature distribution in the power feeder. Note that in the example shown in Fig. 13, contrary to the example shown in Fig. 12, the temperature of the blocks on the left side of the graph is higher than that of the blocks on the right side.

[0077] As described above, in the heater according to the present embodiment, the temperature distribution varies over the entire heater in the longitudinal direction due to the variation in the heat generation amount of the power supply lines for each block. Furthermore, the influence of such variation in the heater temperature distribution is not limited to the fixing device, but also extends to other devices mounted in the image forming apparatus.

[0078] 1, in the image forming apparatus according to this embodiment, the process unit 1Y is disposed near the fixing device 9, and therefore the influence of the variation in temperature distribution in the heater also extends to this process unit 1Y. In addition, the heat of the process unit 1Y close to the fixing device 9 is also transferred to the other process units 1M, 1C, and 1Bk by the rotating intermediate transfer belt 11, and therefore the influence of the variation in temperature distribution in the heater also extends to the other process units 1M, 1C, and 1Bk to a certain extent.

[0079] As a result, the temperature distribution of the cleaning blade 77 of each process unit 1Y, 1M, 1C, and 1Bk also varies, and there is a risk that the cleaning performance may deteriorate in particularly high-temperature portions of the cleaning blade 77. The principle behind the deterioration of the cleaning performance of the cleaning blade 77 will be described below.

[0080] As shown in FIG. 14, the cleaning blade 77 is generally disposed so as to contact the photoreceptor 2 in a counter direction to the rotation direction (surface movement direction) A of the photoreceptor 2. The counter direction means an orientation in which the tip side (free end side) of the cleaning blade 77 held at one end by the blade holding member 78 is located upstream of the rear end side (support end side) in the rotation direction of the photoreceptor 2. When the photoreceptor 2 rotates, the cleaning blade 77 rubs against the surface of the photoreceptor 2. For this reason, a force in the rotation direction A of the photoreceptor 2 acts on the tip (rubbing portion 77a) of the cleaning blade 77, but the cleaning blade 77 is usually held in a state facing the counter direction.

[0081] However, when the cleaning blade 77 is affected by the temperature distribution of the heater described above and the temperature distribution varies, the repulsive elasticity of the cleaning blade 77 against the photoreceptor 2 increases in the parts of the cleaning blade 77 where the temperature is high. In addition, the increased repulsive elasticity increases the frictional force of the cleaning blade 77 against the photoreceptor 2. When the frictional force of the cleaning blade 77 increases, the tip of the cleaning blade 77 is turned upside down by the force in the rotation direction A of the photoreceptor 2, as shown by the dotted line in FIG. 14, so-called curling occurs.

[0082] Thus, in the high temperature portion of the cleaning blade 77, there is a risk of curling due to the influence of the temperature distribution of the heater. Furthermore, when the cleaning blade 77 curls, the contact state of the cleaning blade 77 with the photoconductor 2 is not maintained in an appropriate state, and the cleaning performance of the cleaning blade 77 is reduced.

[0083] Therefore, in this embodiment, the following measures are taken to prevent the cleaning blade 77 from turning over and to maintain the contact state of the cleaning blade 77 with the photoconductor 2 in an appropriate state.

[0084] First, the temperature distribution of the cleaning blade according to the present embodiment will be described with reference to FIG.

[0085] As shown in FIG. 15, the cleaning blade 77 is disposed longitudinally and continuously in the longitudinal direction or rotation axis direction of the photoreceptor 2, which is the direction of the arrow Z in the figure. Therefore, the rubbing portion 77a between the cleaning blade 77 and the photoreceptor 2 also extends in the direction of the arrow Z. The cleaning blade 77 has a longitudinal direction in the same direction as the heater 22. In other words, both the cleaning blade 77 and the heater 22 extend in the paper width direction (direction of the arrow Z). Note that the "paper width direction (recording medium width direction)" here means a direction parallel to the paper surface and perpendicular to the paper transport direction (recording medium transport direction) B. The "paper surface" means the surface with the largest area among the three mutually intersecting surfaces of the paper.

[0086] In this way, since both the cleaning blade 77 and the heater 22 extend longitudinally in the same direction (direction perpendicular to the paper conveying direction) Z, the influence of the temperature distribution in the longitudinal direction of the heater 22 affects the temperature distribution in the longitudinal direction of the cleaning blade 77. In addition, the rubbing portion 77a between the cleaning blade 77 and the photoreceptor 2 and the heat generating region H in which each resistance heating element 60 of the heater 22 is arranged are both arranged over a range including the maximum paper width or the maximum image forming region width, and are set to approximately the same length (length in the direction perpendicular to the paper conveying direction). In addition, the developing device 4 and the like are provided between the rubbing portion 77a and the heater 22. Therefore, both ends of the rubbing portion 77a in the longitudinal direction and both ends of the heater 22 in the longitudinal direction are indirectly opposed to each other. Here, the temperature distribution of the heater 22 affects the intermediate transfer belt 11 and the developing device 4 that are present near the heater 22, and the influence extends to the cleaning blade 77. The cleaning blade 77 is affected by the temperature distribution of the heater 22, so that the temperature is higher at the ends of the rubbing portion 77a than at the center in the longitudinal direction Z (direction perpendicular to the paper transport direction).

[0087] 15 shows the temperature distribution when all the resistance heating elements 60 of the heater 22 generate heat. In this case, the temperature of the heater 22 is high in the first block and the seventh block on both ends e1, e2 in the longitudinal direction of the heat generating region H in which the resistance heating elements 60 are arranged. Therefore, in the cleaning blade 77, the temperature of the portions a1, a2 facing both ends e1, e2 in the longitudinal direction of the heat generating region H of the heater 22 is higher than the temperature of the portion a5 facing the longitudinal center portion c of the heat generating region H of the heater 22.

[0088] 16 shows the temperature distribution when the resistance heating element 60 (only the first heating portion) other than the two ends of the heater 22 generates heat. In this case, the temperature of the heater 22 is high in the second block and the sixth block on the longitudinal ends e1, e2 sides of the heat generation region H of the heater 22. Therefore, in this case as well, the temperature of the cleaning blade 77 is high in the portions a3 and a4 facing the longitudinal ends e1, e2 sides of the heat generation region H of the heater 22 compared to the portion a5 facing the longitudinal center portion c of the heat generation region H of the heater 22.

[0089] Thus, in the cleaning blade 77 according to the present embodiment, the temperature at both ends in the longitudinal direction tends to be higher than the temperature at the center, both in the case of the heat generation mode shown in FIG. 15 and the case of the heat generation mode shown in FIG. 16. Therefore, in the cleaning blade 77 according to the present embodiment, in order to suppress the cleaning blade 77 from turning over, the frictional force of the cleaning blade 77 against the photoreceptor 2 is made lower at both ends of the rubbing portion 77a than at the center in the longitudinal direction. Note that, in the above, the frictional force at the rubbing portion 77a that directly faces the heater 22 is set, but it is also possible to configure the frictional force at the rubbing portion 77a on the side where the amount of heat generated by the heater 22 is higher (the side where the temperature is higher, both ends of the heater 22 in the above embodiment) to be lower. Also, in the above, the heat generation amount at both ends of the heater 22 is higher, but when the heat generation amount at either end of the heater 22 is higher, it is also possible to configure the frictional force at the rubbing portion 77a to be lower on the same side as the side where the amount of heat generated by the heater 22 is higher.

[0090] Incidentally, the frictional force of the cleaning blade against the photoconductor generally includes a static frictional force (maximum static frictional force) that occurs at the moment when the photoconductor starts to rotate, and a kinetic frictional force that occurs thereafter while the photoconductor is rotating. On the other hand, the cleaning blade may turn over in either case, at the moment when the photoconductor starts to rotate, or while the photoconductor is rotating thereafter. In each case, in order to reliably suppress the cleaning blade turning over, it is preferable to lower both the static frictional force and the kinetic frictional force. However, in the present invention, it is sufficient to suppress at least one of the turning over that occurs when the photoconductor starts to rotate and the turning over that occurs while the photoconductor is rotating, so the frictional force in this specification means at least one of the static frictional force and the kinetic frictional force.

[0091] In this manner, in the rubbing portion 77a between the cleaning blade 77 and the photoreceptor 2 according to this embodiment, the frictional force between the cleaning blade 77 and the photoreceptor 2 at both ends in the longitudinal direction on the same side as the side where the temperature of the heater 22 becomes high is low, so that even if the cleaning blade 77 is affected by the temperature distribution of the heater 22, it is possible to effectively suppress the cleaning blade 77 from being turned over due to the rotation of the photoreceptor 2. This makes it possible to maintain the contact state of the cleaning blade 77 with the photoreceptor 2 in an appropriate state and ensure good cleaning performance.

[0092] To ensure good cleaning performance, it is preferable to prevent the cleaning blade 77 from turning over in either the heat generation mode shown in Fig. 15 or the heat generation mode shown in Fig. 16. Therefore, in this embodiment, the frictional force of each of the portions a1, a2, a3, and a4 of the cleaning blade 77 facing the first block, the seventh block, the second block, and the sixth block, which become higher in temperature in each heat generation mode, is made lower than the frictional force of the central portion a5.

[0093] However, the portions and ranges of the cleaning blade 77 where the frictional force is reduced can be changed as appropriate. For example, if it is necessary to suppress curling in a heating mode where the temperature distribution variation is particularly noticeable (in the example shown in FIG. 15), the frictional force may be lower only in portions a1 and a2 of the cleaning blade 77 facing the first block and the seventh block, compared to the other portions. Furthermore, the frictional force does not have to be set for each block in which the resistance heating element 60 is arranged. For example, the frictional force may change continuously or stepwise within one block.

[0094] Furthermore, the portion of the cleaning blade 77 that is likely to turn up, i.e., the portion of the heater 22 that has a high temperature, can be identified by comparing the amount of heat generated at each portion in the longitudinal direction (paper width direction) of the heater 22. Note that the "amount of heat generated at each portion in the longitudinal direction of the heater 22" mentioned here includes the amount of heat generated by the resistance heating element 60 as well as the amount of heat generated by the power supply line 62.

[0095] Also, as expressed by the above formula (1), the amount of heat generated (W) is proportional to the square of the current (I), so the sum of the squares of the currents flowing through the power feed lines may be used to determine the magnitude relationship of the amounts of heat generated by the heater 22. However, since the "current flowing through the power feed line 62" referred to here is a current used to determine the magnitude relationship of the amounts of heat generated by the heater 22, the current flowing through each of the power feed lines 62A, 62B, and 62D in the area where the resistance heating elements 60 at both ends that do not generate heat are arranged as in the example shown in FIG. 16 is not included in the "current flowing through the power feed line 62". In other words, the "current flowing through the power feed line 62" used to determine the magnitude relationship of the amounts of heat generated by the heater 22 means the current flowing through the power feed line 62 in the area where the resistance heating elements 60 that generate heat are arranged. Note that in the example shown in FIG. 16, a small amount of current is also passed through the resistance heating elements 60 at both ends due to unintended shunting (see FIG. 13), so strictly speaking, the environment is such that the resistance heating elements 60 at both ends can generate heat. However, the above-mentioned "resistance heating element 60 that generates heat" refers to the resistance heating element 60 that generates heat by normal current flow. Therefore, the resistance heating element 60 that may generate a small amount of heat due to unintended shunting is not considered as an area for determining the magnitude relationship of the amount of heat generated.

[0096] Specifically, the frictional force of the cleaning blade 77 against the photoreceptor 2 can be reduced by the following methods.

[0097] First, to explain frictional force, as shown in the following formula (2), the frictional force (F) of the cleaning blade against the photoreceptor is calculated by multiplying the friction coefficient (μ) between the photoreceptor and the cleaning blade by the contact pressure (N) of the cleaning blade against the photoreceptor.

[0098]

number

[0099] Therefore, according to the above formula (2), by reducing the contact pressure (N) of the cleaning blade against the photoreceptor, it is possible to lower the frictional force (F) of the cleaning blade. Further, the contact pressure of the cleaning blade varies according to the length J (see FIG. 14; hereinafter referred to as "free length") of the portion where the cleaning blade 77 protrudes from the blade holding member 78 toward the photoreceptor 2 side. That is, the longer the free length J of the cleaning blade 77, the easier it is for the cleaning blade 77 to bend, and thus the contact pressure of the cleaning blade 77 against the photoreceptor 2 becomes smaller.

[0100] Therefore, as in the example shown in FIG. 17, by making the free length of the cleaning blade 77 longer at both ends than at the central portion in the longitudinal direction (arrow Z direction) (J1 < J2), it is possible to lower the frictional force at both ends where curling is likely to occur.

[0101] Also, in the example shown in FIG. 17, the lengths R1 and R2 of the portion of the blade holding member 78 that holds the cleaning blade 77 continuously change from the central portion in the longitudinal direction toward both ends. That is, in this case, by making the length of the portion of the blade holding member 78 that holds the cleaning blade 77 shorter at both ends than at the central portion (R1 > R2), the free length of the cleaning blade 77 is made longer at both ends than at the central portion.

[0102] The shape of the blade holding member 78 can be changed as appropriate. For example, an example shown in FIG. 18 or FIG. 19 may be adopted. In the example shown in FIG. 18 or FIG. 19, the length of the portion of the blade holding member 78 that holds the cleaning blade 77 is short at both ends in the longitudinal direction and in the vicinity thereof, where curling is particularly likely to occur (R1>R2). In this case, only both ends in the longitudinal direction of the blade holding member 78 and the portions in the vicinity thereof are processed to be short, and other portions do not need to be processed, so that the processing cost of the blade holding member 78 can be reduced. The tip shape of the blade holding member 78 at both ends in the longitudinal direction and in the vicinity thereof may be a shape inclined with respect to the longitudinal direction as in the example shown in FIG. 18, or may be a step shape perpendicular to the longitudinal direction as in the example shown in FIG. 19.

[0103] As another method for reducing the frictional force, a method of varying the thickness of the cleaning blade 77 along its length (arrow Z direction) may be employed, as shown in Fig. 20. Here, the "thickness" of the cleaning blade 77 refers to the dimension in the direction (arrow U direction) intersecting both the length of the cleaning blade 77 (arrow Z direction) and the length direction (arrow V direction) in which the cleaning blade 77 protrudes from the blade holding member 78. When the thickness of the cleaning blade 77 is reduced, the cleaning blade 77 becomes more likely to bend, and therefore the contact pressure of the cleaning blade 77 with the photoreceptor 2 can be reduced, thereby reducing the frictional force.

[0104] 20, by making the thickness of the cleaning blade 77 thinner at both ends than at the center in the longitudinal direction (T1>T2), it is possible to reduce the frictional force of the cleaning blade 77 at both ends where curling is likely to occur. Similarly to the above-mentioned free length of the cleaning blade 77, the thickness of the cleaning blade 77 may be continuously thinner from the center in the longitudinal direction toward both ends, or may be thinner only at both ends in the longitudinal direction and in their vicinity where curling is particularly likely to occur.

[0105] Alternatively, a different material may be used for the cleaning blade 77. That is, by using a material with low resilience for the cleaning blade 77, the contact pressure of the cleaning blade 77 with the photoreceptor 2 becomes smaller, thereby reducing the frictional force.

[0106] 21, for example, both end portions in the longitudinal direction of cleaning blade 77 (hatched portions in the figure) are made of a material with lower resilience than the other portions (including the central portion). In this case, the frictional force of cleaning blade 77 at both end portions where curling is likely to occur is lower, so curling at both end portions can be suppressed.

[0107] The portion where the material is made different is not limited to the entire portion of the cleaning blade 77 in the thickness direction U as in the example shown in Fig. 21 above, but may be only a portion of the thickness direction U (the shaded portion in the figure) as in the example shown in Fig. 22. When the material of the cleaning blade 77 is made different in a portion of the thickness direction U, it is particularly preferable that the portion of the cleaning blade 77 on the contact side with the photoconductor 2 be made of a low-resilience material.

[0108] As another method, the lubricity of the cleaning blade 77 with respect to the photoconductor 2 may be increased at both ends where the cleaning blade 77 is likely to turn over. For example, as shown in FIG. 23, the lubricant supplied to the photoconductor 2 in regions b1 and b2 at both ends of the cleaning blade 77 where the blade is likely to turn over is made to have a higher lubricity than the lubricant supplied to other regions (including the central region). This reduces the frictional force at both ends in the longitudinal direction of the cleaning blade 77, thereby suppressing the blade from turning over. Alternatively, the lubricant may be supplied to the photoconductor 2 only in the region of the cleaning blade 77 where it is desired to increase the lubricity.

[0109] As the lubricant, for example, a solid lubricant containing a fatty acid metal salt (a fatty acid metal salt having a lamellar crystal structure such as a fluororesin, zinc stearate, calcium stearate, barium stearate, aluminum stearate, or magnesium stearate, or lauroyl lysine, sodium zinc monocetyl phosphate, or calcium lauroyl taurate, etc.) can be used. In addition, a liquid lubricant such as silicone oil, fluorine oil, or natural wax may be used.

[0110] In addition, it is possible to use in combination the various methods described above for reducing the frictional force of the cleaning blade 77. For example, by increasing the free length and decreasing the thickness at both ends of the cleaning blade 77 in the longitudinal direction, it is possible to more effectively reduce the frictional force.

[0111] In the above example, the frictional force at both ends of the cleaning blade 77 is made lower than that at the center, but it is also possible to make the frictional force lower only at one end of the cleaning blade 77. For example, as in the example shown in Fig. 15, when the seventh block of the heater 22 has the highest temperature, the frictional force may be made lower only at one end of the cleaning blade 77 that faces the seventh block than at the other parts.

[0112] That is, in the present invention, it is sufficient that the frictional force of the cleaning blade 77 against the photoreceptor 2 is lower in a portion of the rubbing portion 77a between the cleaning blade 77 and the photoreceptor 2 that faces a region where the amount of heat generated by the heater 22 is the largest than in a portion that faces a region where the amount of heat generated by the heater 22 is the smallest, or, in terms of using the current flowing through the power supply line 62 instead of the amount of heat generated by the heater 22, in the present invention, it is sufficient that the frictional force of the cleaning blade 77 against the photoreceptor 2 is lower in a portion of the rubbing portion 77a between the cleaning blade 77 and the photoreceptor 2 that faces a region where the current flowing through the power supply line 62 is the largest than in a portion that faces a region where the current flowing through the power supply line 62 is the smallest.

[0113] Further, the present invention is not limited to the cleaning blade 77 that cleans the surface of the photoreceptor 2, but can also be applied to a blade that rubs against a rotating body other than the photoreceptor 2. For example, the present invention can also be applied to the cleaning blade 69 that cleans the surface of the intermediate transfer belt 11 shown in FIG.

[0114] FIG. 24 is a diagram showing the positional relationship between a cleaning blade 69 that cleans the surface of the intermediate transfer belt 11 and a heater 22 provided in the fixing device.

[0115] As shown in FIG. 24, the cleaning blade 69 for the intermediate transfer belt also extends longitudinally in the same direction Z as the heater 22 (direction perpendicular to the paper conveying direction), so that the temperature distribution in the longitudinal direction of the heater 22 affects the temperature distribution in the longitudinal direction of the cleaning blade 69. In addition, the rubbing portion 69a between the cleaning blade 69 and the intermediate transfer belt 11 and the heat generating region H in which the resistance heating elements 60 of the heater 22 are arranged are all arranged over a range including the maximum paper width or the maximum image forming region width, and are set to approximately the same length (length in the direction perpendicular to the paper conveying direction). In addition, a frame of the belt cleaning device 10 is provided between the rubbing portion 69a and the heater 22. Therefore, both longitudinal ends of the rubbing portion 69a of the cleaning blade 69 for the intermediate transfer belt also indirectly face both longitudinal ends of the heater 22.

[0116] Here, as in the above-described embodiment, the heater 22 has a higher temperature at both ends e1, e2 than at the center c in the longitudinal direction of the heat generating region H. Therefore, the cleaning blade 69 for the intermediate transfer belt is also affected by the temperature distribution of the heater 22, and therefore has a higher temperature at both ends than at the center in the longitudinal direction (direction perpendicular to the paper transport direction) Z. Since the cleaning blade 69 for the intermediate transfer belt is closer to the heater 22, it is more susceptible to the heat of the heater 22 than the cleaning blade 77 for the photoconductor described above.

[0117] In this way, the temperature of both ends in the longitudinal direction of the cleaning blade 69 for the intermediate transfer belt is higher than that of the central portion, so that the cleaning blade 69 may turn over at both ends. Therefore, it is preferable to apply the present invention to the cleaning blade 69 for the intermediate transfer belt. That is, in the rubbing portion 69a between the cleaning blade 69 and the intermediate transfer belt 11, it is preferable to make the frictional force between the cleaning blade 69 and the intermediate transfer belt 11 at both ends in the longitudinal direction, which are the same side as the side where the temperature of the heater 22 is high, lower than the frictional force between the cleaning blade 69 and the intermediate transfer belt 11 at the longitudinal center portion. This makes it possible to effectively suppress the cleaning blade 69 for the intermediate transfer belt from turning over due to the rotation of the intermediate transfer belt 11. In addition, as a specific configuration for lowering the frictional force between the cleaning blade 69 and the intermediate transfer belt 11, each configuration in the above-mentioned embodiment can be applied. In the above, the frictional force is set at the sliding portion 69a that directly faces the heater 22, but it is also possible to configure the frictional force to be lower at the sliding portion 69a on the side where the amount of heat generated by the heater 22 is higher (the side where the temperature is higher, in the above embodiment, both ends of the heater 22). Also, in the above, a configuration in which the amount of heat generated by both ends of the heater 22 is higher has been described, but when the amount of heat generated by either end of the heater 22 is higher, it is also possible to configure the frictional force to be lower on the same side of the sliding portion 69a as the side where the amount of heat generated by the heater 22 is higher.

[0118] Furthermore, the present invention is applicable not only to the cleaning blade 77 for the photoconductor and the cleaning blade 69 for the intermediate transfer belt, but also to a cleaning blade 38 that cleans the surface of a secondary transfer belt 39 as a transfer member, as in the example shown in Figure 25.

[0119] As described above, according to the present invention, even if there is variation in the temperature distribution of the heating member, the curling of the blade caused by such variation can be suppressed, and therefore the present invention is particularly suitable for image forming devices equipped with a heating member in which variation in temperature distribution is likely to occur.

[0120] An example of a heating member that is prone to temperature distribution variations is the heater 22, which may cause the above-mentioned unintended shunting, but the configuration of the heater provided in the image forming apparatus according to the present invention is not limited to the above-mentioned configuration. For example, the present invention can also be applied to an image forming apparatus provided with a heater 22 as shown in FIG.

[0121] The heater 22 shown in Fig. 26 differs from the heater 22 shown in Fig. 11 in that all of the electrode portions 61A, 61B, 61C are disposed at one end side in the longitudinal direction of the heater 22 (the left end side in Fig. 26). That is, the heater 22 shown in Fig. 26 and the heater 22 shown in Fig. 11 have the second electrode portions 61B disposed in the left-right direction of the figure reversed to each other. Therefore, in the heater 22 shown in Fig. 26, each resistance heating element 60 and the second electrode portion 61B are connected via not only the second power supply line 62B but also a fifth power supply line 62E provided so as to be folded back from the end of the second power supply line 62B in the longitudinal direction (the direction of the arrow Z).

[0122] However, the heater 22 shown in FIG. 26 has the same layout of the conductive paths as the heater 22 shown in FIG. 11 in the following respects, and therefore, when power is supplied to the resistance heating elements 60 (first heat generating portions 60A) other than the two ends, unintended shunting occurs similarly. That is, the heater 22 shown in FIG. 26 and the heater 22 shown in FIG. 11 have a first conductive path K1, a second conductive path K2, and a third conductive path K3 as conductive paths common to each of them. Specifically, the first conductive path K1 is a conductive path that connects each of the resistance heating elements 60 (first heat generating portions 60A) other than the two ends to the first electrode portion 61A. The second conductive path K2 is a conductive path that extends from each of the resistance heating elements 60 other than the two ends to the first direction S1 side (rightward in FIG. 11 or FIG. 26) of the longitudinal direction of the heater 22 and is directly or indirectly connected to the second electrode portion 61B. In addition, the third conductive path K3 is a conductive path that branches off from the second conductive path K2 and extends in the second direction S2 (the left direction in Figure 11 or Figure 26) opposite to the first direction S1, and is connected to the second conductive path K2 without passing through the first conductive path K1.

[0123] Fig. 27 is a diagram showing the heat generation amount of each of the power supply lines 62A, 62B, 62D, and 62E for each block and their total value when the resistance heating elements 60 other than those at both ends generate heat in the heater 22 shown in Fig. 26. As shown in the table and graph in Fig. 27, in this case as well, the total heat generation amount of the power supply lines is large in the blocks at both ends (second block and sixth block) and conversely is small in the block at the center (fourth block). Therefore, the temperature is higher at both ends than in the center in the longitudinal direction of the heater 22.

[0124] Moreover, Fig. 28 is a diagram showing the heat generation amount of each of the power supply lines 62A, 62B, 62D, 62E for each block and the total value thereof when all of the resistance heating elements 60 generate heat in the heater 22 shown in Fig. 26. In this case as well, the total heat generation amount of the power supply lines is large in the blocks on both ends (first block and seventh block) and conversely is small in the block in the center (fourth block), so that the temperature is higher at both ends than in the center in the longitudinal direction of the heater 22.

[0125] Thus, the heater 22 shown in FIG. 26 also has a temperature distribution in which the temperature is higher at both ends than at the center in the longitudinal direction. Therefore, by applying the present invention, it is possible to effectively suppress curling of the blade caused by this temperature distribution.

[0126] Furthermore, according to the present invention, it is possible to improve the blade problem (curling) caused by variations in temperature distribution of the heating element, and therefore it is also possible to accommodate configurations using small heaters that are prone to variations in temperature distribution, or heaters with increased heat generation to increase speed.

[0127] Specifically, the present invention is expected to be highly effective when applied to an image forming apparatus equipped with a small heater as described below.

[0128] Table 1 below shows the results of a test to investigate the variation in temperature distribution that occurs in a heater when the heater is miniaturized in the short side direction. Specifically, in this test, multiple types of heaters with different ratios (R / Q) of the short side dimension R of each resistance heating element 60 to the short side dimension Q of the base material 50 shown in FIG. 29 were prepared, and the temperature difference between the center and end of the heat generation area in the longitudinal direction of each heater was measured. In addition, in this test, the surface temperature of each heater was measured using an infrared thermography (FLIR T620) manufactured by FLIR Systems. Note that when the short side dimension ratio (R / Q) is 80% or more, the ratio of the short side dimension of each resistance heating element 60 to the short side dimension of the base material 50 becomes too large, making it practically difficult to secure the installation space for the power supply line, so the measurement was withheld.

[0129] [Table 1]

[0130] As shown in Table 1, the larger the short-side dimension ratio (R / Q), the larger the temperature difference between the center and the ends in the longitudinal direction of the heat generating region. Therefore, in a heater with a large short-side dimension ratio (R / Q), i.e., a heater that is compact in the short-side direction, there is a risk that the temperature variation at both ends in the longitudinal direction will also be significant. In particular, in a heater with a short-side dimension ratio (R / Q) of 25% or more or 40% or more, the temperature difference between the center and the ends in the longitudinal direction in the heat generating region will be large (5°C or more), so there is a risk that the temperature variation at both ends in the longitudinal direction will also be significant. Therefore, the present invention can be expected to be particularly effective when applied to an image forming apparatus equipped with a heater with a short-side dimension ratio (R / Q) of 25% or more and less than 80%, or 40% or more and less than 80%.

[0131] The heater provided in the fixing device is not limited to the heater 22 having a block-shaped (rectangular) resistance heating element 60 as shown in FIG. 29, but may be a heater 22 having a resistance heating element 60 in a shape of a folded straight line as shown in FIG. 30. In the case of the heater 22 shown in FIG. 30, the short-side dimension R of the resistance heating element 60 does not mean the thickness of one linear part of the resistance heating element formed to be folded back, but means the short-side dimension of the entire resistance heating element 60. The base material 50 may have a shape in which the short-side dimension Q changes depending on the position in the longitudinal direction. However, in this case, the minimum short-side dimension of the base material 50 within the longitudinal range (within the heat generation area) in which each resistance heating element 60 is arranged is defined as the short-side dimension Q of the base material 50.

[0132] In addition, in the embodiment according to the present invention, a resistive heating element having a PTC characteristic may be used to suppress temperature variation in the longitudinal direction of the heater. The PTC characteristic is a characteristic in which the resistance value increases as the temperature increases (when a constant voltage is applied, the heater output decreases). When the heating part has the PTC characteristic, the heater can be started up quickly by high output when the heater is at a low temperature, and the heater can be prevented from overheating by low output when the heater is at a high temperature. For example, if the TCR coefficient of the PTC characteristic is about 300 to 4000 ppm / degree, the cost can be reduced while ensuring the resistance value required for the heater. More preferably, the TCR coefficient is 500 to 2000 ppm / degree.

[0133] The temperature coefficient of resistance (TCR) can be calculated using the following formula (3). In formula (3), T0 is a reference temperature, T1 is an arbitrary temperature, R0 is a resistance value at the reference temperature T0, and R1 is a resistance value at the arbitrary temperature T1. For example, in the heater 22 described above and shown in FIG. 11, if the resistance value between the first electrode portion 61A and the second electrode portion 61B is 10Ω (resistance value R0) at 25°C (reference temperature T0) and 12Ω (resistance value R1) at 125°C (arbitrary temperature T1), the temperature coefficient of resistance is 2000 ppm / °C from formula (3).

[0134]

number

[0135] Furthermore, the present invention is not limited to the above-described fixing device as shown in FIG. 3, but can also be applied to an image forming apparatus equipped with a fixing device as shown in FIGS.

[0136] 31 differs from the above-mentioned fixing devices in that a fixing nip N1 through which paper P passes and a heating nip N2 for heating fixing belt 20 by heater 22 are set at different positions. Specifically, different pressure rollers 91, 92 are pressed against heater 22 and nip forming member 90, which are arranged 180° opposite each other in the rotation direction of fixing belt 20, to form fixing nip N1 and heating nip N2.

[0137] Fixing device 9 shown in Fig. 32 is an example in which pressure roller 92 on the heater 22 side of the fixing device shown in Fig. 31 is omitted, and further heater 22 is formed in an arc shape to match the curvature of fixing belt 20. Other than that, it is the same as the configuration shown in Fig. 31. In this case, by forming heater 22 in an arc shape, the contact length between fixing belt 20 and heater 22 in the belt rotation direction is secured, and fixing belt 20 can be heated efficiently.

[0138] Finally, the fixing device 9 shown in Fig. 33 is an example in which belts 94 and 95 are disposed on both sides of a roller 93. In this case, as in the example shown in Fig. 31, a fixing nip N1 and a heating nip N2 are set at different positions. That is, on the right side of the figure, a nip forming member 90 is pressed against the roller 93 via one belt 94, and on the left side of the figure, a heater 22 is pressed against the roller 93 via the other belt 95, thereby forming the respective nip portions N1 and N2.

[0139] By applying the present invention to an image forming apparatus equipped with such a fixing device as shown in Figures 31 to 33, it is possible to suppress the blade from turning over due to the variation in temperature distribution of the heating member, thereby improving image quality and enabling miniaturization and high speed operation. In the present invention, "directly facing" refers to a state in which the sliding portion and the heating member are facing each other without any blocking member between them, and "indirectly facing" refers to a state in which another member or the like is interposed between the sliding portion and the heating member. The present invention can be applied to either state without any problem.

[0140] Furthermore, the present invention is not limited to application to an image forming apparatus equipped with a fixing device, which is an example of a heating device, but can also be applied to an image forming apparatus equipped with a heating device that heats a recording medium for purposes other than image fixing. [Explanation of symbols]

[0141] 2 Photoconductor (rotating body) 9 Fixing device (heating device) 22 Heater (heating element) 50 Base material 60 Resistance Heating Element 61 Electrode section 62 Power supply line (conductive part) 77 Cleaning blade (blade) 77a Sliding part 100 Image forming device P Paper (recording medium) [Prior art documents] [Patent documents]

[0142] [Patent Document 1] JP 2016-62024 A

Claims

1. A blade that rubs against a rotating body; a heating device for heating the recording medium being conveyed; The heating device includes a heating member having a heating element. In an image forming apparatus, the heating member extends in a direction perpendicular to a conveying direction of the recording medium, the sliding portion between the blade and the rotating body extends in a direction perpendicular to the conveying direction of the recording medium, Both ends of the sliding portion and both ends of the heating member face each other directly or indirectly, the heating member has a heat generating region in which a plurality of blocks, each of which is partitioned for each of the heat generating elements, are arranged in a direction perpendicular to the transport direction, the block positioned at one end in the heat generating region in a direction perpendicular to the transport direction generates a larger amount of heat than the block positioned at the center, An image forming apparatus characterized in that the friction force between the blade and the rotating body at the sliding portion that directly or indirectly faces the block located at the one end side is lower than the friction force between the blade and the rotating body at the sliding portion that directly or indirectly faces the block located at the central portion.

2. A blade that rubs against a rotating body; a heating device for heating the recording medium being conveyed; The heating device includes a heating member having a heating element. In an image forming apparatus, the heating member extends in a direction perpendicular to a conveying direction of the recording medium, the sliding portion between the blade and the rotating body extends in a direction perpendicular to the conveying direction of the recording medium, The sliding portion and the heating member face each other directly or indirectly, the heating member has a heat generating region in which a plurality of blocks, each of which is partitioned for each of the heat generating elements, are arranged in a direction perpendicular to the transport direction, the block located at one end in the heating region in the direction perpendicular to the transport direction has a larger total value of the square of the current than the block located at the center, An image forming apparatus characterized in that the friction force between the blade and the rotating body at the sliding portion that directly or indirectly faces the block located at the one end side is lower than the friction force between the blade and the rotating body at the sliding portion that directly or indirectly faces the block located at the central portion.

3. The blocks located at both ends in the heat generation area in a direction perpendicular to the conveying direction generate a larger amount of heat than the blocks located in the center, 2. An image forming apparatus as described in claim 1, wherein the friction force between the blade and the rotating body at the sliding portion that directly or indirectly faces the blocks located at both ends is lower than the friction force between the blade and the rotating body at the sliding portion that directly or indirectly faces the blocks located in the central portion.

4. The blocks located at both ends in the heating region in a direction perpendicular to the transport direction have a larger sum of squares of currents than the blocks located in the center, 3. An image forming apparatus as described in claim 2, wherein the friction force between the blade and the rotating body at the sliding portion that directly or indirectly faces the blocks located at both ends is lower than the friction force between the blade and the rotating body at the sliding portion that directly or indirectly faces the block located in the central portion.

5. 5. The image forming apparatus according to claim 1, wherein a contact pressure between the blade and the rotating body is smaller in a portion where frictional force between the blade and the rotating body is low than in a portion where frictional force between the blade and the rotating body is high.

6. An image forming apparatus according to any one of claims 1 to 5, wherein the length of the portion of the blade protruding from the blade holding member toward the rotating body is longer in the portion where the frictional force between the blade and the rotating body is low than in the portion where the frictional force between the blade and the rotating body is high.

7. 7. An image forming apparatus as described in claim 6, wherein the length of the portion of the blade that protrudes from the blade holding member toward the rotating body is longer in the portion where the frictional force between the blade and the rotating body is low than in the portion where the frictional force between the blade and the rotating body is high, due to the length of the portion of the blade holding member that holds the blade being shorter than the portion where the frictional force between the blade and the rotating body is high.

8. 8. The image forming apparatus according to claim 1, wherein a portion of the blade having a low frictional force between the blade and the rotating body is thinner than a portion of the blade having a high frictional force between the blade and the rotating body.

9. 9. An image forming apparatus according to claim 1, wherein a portion of the blade having a low frictional force between the blade and the rotating body has a lower resilience against the rotating body than a portion of the blade having a high frictional force between the blade and the rotating body.

10. 10. An image forming apparatus according to claim 1, wherein a portion of the blade having a low frictional force between the blade and the rotating body has a higher lubricity with respect to the rotating body than a portion of the blade having a high frictional force between the blade and the rotating body.

Images