Fixing device, image forming apparatus

Abstract

To prevent lubricant from being scraped off by a conductive member.SOLUTION: A fixing device 9 comprises: a fixing belt 20; a pressure roller 21 that applies a pressure to the fixing belt 20 to form a fixing nip N between the fixing belt 20 and the pressure roller; a conductive member 40 that is grounded and in contact with an inner face of the fixing belt 20; and a heater 22. The conductive member 40 has a limiting part limiting a contact range with the fixing belt 20 at a contact part 40a provided at an end facing the fixing belt 20.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a fixing device and an image forming apparatus. [Background technology]

[0002] The fixing device is provided with a fixing belt as a rotating member, a heater as a heating element that contacts the inner surface of the fixing belt to heat it, a pressure roller that pressurizes the fixing belt, etc. Some types of heater generate heat by applying an AC voltage to a resistance heating element formed on a base material, and heat the inner surface of the fixing belt via an insulating layer or the like.

[0003] In a configuration where an AC voltage is applied to the heater, the insulating layer on the heater and the surface layer of the fixing belt act as capacitors, and the AC voltage is applied to the fixing nip via the fixing belt. When paper is in contact with both the transfer nip and the fixing nip, this AC voltage propagates through the paper to the transfer nip. This causes the AC voltage to affect the transfer electric field, resulting in periodic density variations in the transferred image, known as image banding. This problem is particularly pronounced in high-humidity environments or when using thin paper with low resistance.

[0004] In response to this, there has conventionally been a fixing device configured such that a conductive member is in contact with the inner surface of the fixing belt, and the current is released to the ground side via this conductive member.

[0005] For example, Patent Document 1 (Japanese Patent Laid-Open Publication No. 2005-166299) discloses a configuration in which a tip-shaped end member provided at the end of a conductive member slides against the inner surface of a metal film.

[0006] The inner surface of the fixing belt is provided with a lubricant to improve sliding between the belt and the heater, but when a conductive member comes into contact with the inner surface of the fixing belt, the lubricant is scraped off, causing the fixing belt to wear out. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to suppress scraping of lubricant by a conductive member. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention provides a fixing device including a rotating member, a pressure member that presses the rotating member and forms a fixing nip between the rotating member and the pressure member, a conductive member that is grounded and in contact with the inner surface of the rotating member, and a heating element that contacts the inside of the rotating member and heats the rotating member, wherein the conductive member has a limiting portion at a contact portion provided at an end portion on the rotating member side that limits the contact area with the rotating member. The limiting portion has a tapered shape in which its width narrows toward the tip of the conductive member on the rotating member side. It is characterized by: [Effects of the Invention]

[0009] According to the present invention, it is possible to prevent the conductive member from scraping off the lubricant. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating the configuration of an image forming apparatus. [Figure 2] FIG. 10 is a side cross-sectional view of a fixing device provided with a fixing member for fixing a conductive member. [Figure 3] FIG. 10 is a diagram illustrating the formation of a banding image. [Figure 4] FIG. 10 is a diagram showing the longitudinal arrangement of conductive members. [Figure 5] 10(a) and 10(b) are diagrams showing other configurations of the limiting portion provided on the contact portion. [Figure 6] 4, 5(a), and 5(b) are views in which slits are provided in the contact portions of the contact portions of FIGS. 4, 5(a), and 5(b), respectively. [Figure 7] 10A and 10B are diagrams illustrating other examples of conductive members. [Figure 8] 10A and 10B are diagrams illustrating other examples of conductive members. [Figure 9]FIG. 2 is a perspective view of a conductive member having a bent portion and its surroundings. [Figure 10] FIG. 2 is a perspective view showing the longitudinal arrangement of conductive members. [Figure 11] 1 is a side cross-sectional view showing a schematic configuration of a fixing device according to an embodiment of the present invention. [Figure 12] FIG. 10 is a diagram showing the inclination of a conductive member. [Figure 13] 12 is a side cross-sectional view of a fixing device different from those in FIGS. 2 and 11. FIG. [Figure 14] FIG. 14 is a perspective view showing the conductive member of FIG. [Figure 15] 14 is a perspective view showing the conductive member and the locking hole of the stay in the embodiment of FIG. 13. FIG. [Figure 16] 16 is a perspective view showing a state in which the conductive member of FIG. 15 is locked in a locking hole. FIG. [Figure 17] 10A and 10B are diagrams illustrating an example of the longitudinal arrangement of conductive members. [Figure 18] FIG. 18 is a diagram showing an example in which the longitudinal arrangement of conductive members is different from that of FIG. [Figure 19] 10 is a side cross-sectional view of a fixing device according to an embodiment in which a conductive member is provided in an insertion hole of a guide rib. FIG. [Figure 20] 10A and 10B are side cross-sectional views of a fixing device according to an embodiment in which the extending direction of the conductive member is different. [Figure 21] FIG. [Figure 22] FIG. 10 is a diagram illustrating power supply to a heater. [Figure 23] FIG. 22 is a plan view of a heater having a different resistive heating element shape from that of FIG. 21. [Figure 24] FIG. 24 is a plan view of a heater having a resistance heating element with a different shape from those in FIGS. 21 and 23. [Figure 25] 1A and 1B are diagrams showing the temperature distribution in the arrangement direction of the fixing belt, in which FIG. 1A is a plan view of the heater, and FIG. 1B is a diagram showing the temperature distribution of the fixing belt. [Figure 26] FIG. 24 is a diagram showing divided regions of the heater in FIG. 23. [Figure 27] FIG. 27 is a diagram showing divided regions having a different shape from that shown in FIG. 26. [Figure 28] FIG. 25 is a diagram showing divided regions of the heater in FIG. 24. [Figure 29] FIG. 2 is a perspective view of a heater, a first high thermal conductive member, and a heater holder. [Figure 30] FIG. 2 is a plan view of the heater showing the arrangement of the first high thermal conductivity members. [Figure 31] 10A and 10B are plan views of a heater showing different examples of the arrangement of first high thermal conductivity members. [Figure 32] FIG. 10 is a plan view of a heater showing yet another example of the arrangement of first high thermal conductivity members. [Figure 33] 3 is a side cross-sectional view showing a schematic configuration of a fixing device according to an embodiment different from that shown in FIG. 2. [Figure 34] FIG. 2 is a perspective view of a heater, a first highly thermally conductive member, a second highly thermally conductive member, and a heater holder. [Figure 35] FIG. 3 is a plan view of the heater showing the arrangement of the first and second high thermal conductive members. [Figure 36] 3A to 3C are plan views of a heater showing examples of different arrangements of the first and second high thermal conductive members. [Figure 37] FIG. 1 illustrates the atomic crystal structure of graphene. [Figure 38] FIG. 1 illustrates the atomic crystal structure of graphite. [Figure 39] 36 is a plan view showing a heater in which the arrangement of the second high thermal conductive members is different from that in FIG. 35. FIG. [Figure 40] 34 is a side cross-sectional view showing a schematic configuration of a fixing device according to an embodiment different from that shown in FIGS. 2 and 33. FIG. [Figure 41] FIG. 2 is a side cross-sectional view showing a schematic configuration of a fixing device different from the above. [Figure 42] FIG. 2 is a side cross-sectional view showing a schematic configuration of a fixing device different from the above. [Figure 43] FIG. 2 is a side cross-sectional view showing a schematic configuration of a fixing device different from the above. [Figure 44] FIG. 2 is a schematic diagram illustrating the configuration of an image forming apparatus different from that in FIG. [Figure 45] 1 is a side cross-sectional view showing a schematic configuration of a fixing device according to an embodiment of the present invention. [Figure 46] FIG. 46 is a plan view of a heater in the fixing device of FIG. 45. [Figure 47] FIG. 2 is a perspective view of a heater and a heater holder. [Figure 48] FIG. 4 is a perspective view showing a state in which a connector is attached to a heater. [Figure 49] FIG. 2 is a diagram showing the arrangement of a thermistor and a thermostat. [Figure 50] FIG. 10 is a view showing a groove portion of a flange. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will be appropriately simplified or omitted. Below, a fixing device provided in an image forming apparatus will be described as a heating device according to one embodiment of the present invention.

[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 four imaging units 1Y, 1M, 1C, and 1Bk that are detachable from the image forming apparatus main body. Each imaging unit 1Y, 1M, 1C, and 1Bk has the same configuration except that it contains a different color developer: yellow, magenta, cyan, or black. These color developers correspond to the color separation components of a color image. Each imaging unit 1Y, 1M, 1C, and 1Bk includes a drum-shaped photoconductor 2 as an image carrier, a charging device 3, a developing device 4, and a cleaning device 5. The charging device 3 charges the surface of the photoconductor 2. The developing device 4 supplies toner as a developer to the surface of the photoconductor 2 to form a toner image. The cleaning device 5 cleans the surface of the photoconductor 2.

[0014] The image forming apparatus 100 also includes an exposure device 6, a paper feed device 7, a transfer device 8, a fixing device 9 as a heating device, and a paper discharge device 10. The exposure device 6 exposes the surface of each photoconductor 2 to light and forms an electrostatic latent image on that surface. The paper feed device 7 supplies paper P as a recording medium to a paper transport path 14. The transfer device 8 transfers the toner image formed on each photoconductor 2 to the paper P. The fixing device 9 fixes the toner image transferred to the paper P to the surface of the paper P. The paper discharge device 10 discharges the paper P outside the apparatus. The imaging units 1, photoconductors 2, charging devices 3, exposure device 6, transfer device 8, etc. constitute image forming means for forming an image on paper.

[0015] The transfer device 8 has an endless intermediate transfer belt 11 as an intermediate transfer body, four primary transfer rollers 12 as primary transfer members, and a secondary transfer roller 13 as a secondary transfer member. The intermediate transfer belt 11 is stretched by multiple rollers. The primary transfer rollers 12 transfer the toner images on the photoconductors 2 to the intermediate transfer belt 11. The secondary transfer rollers 13 transfer the toner images transferred onto the intermediate transfer belt 11 to paper P. Each of the multiple primary transfer rollers 12 contacts the photoconductors 2 via the intermediate transfer belt 11. This brings the intermediate transfer belt 11 and each photoconductor 2 into contact with each other, forming a primary transfer nip between them. Meanwhile, the secondary transfer roller 13 contacts one of the rollers stretching the intermediate transfer belt 11 via the intermediate transfer belt 11. This forms a secondary transfer nip between the secondary transfer roller 13 and the intermediate transfer belt 11.

[0016] Further, a pair of timing rollers 15 is provided in the paper transport path 14 between the paper feeder 7 and the secondary transfer nip (secondary transfer roller 13).

[0017] Next, the printing operation of the image forming apparatus will be described with reference to FIG.

[0018] When a command to start a printing operation is issued, in each of the imaging units 1Y, 1M, 1C, and 1Bk, the photoconductor 2 is rotated clockwise in FIG. 1, and the charging device 3 charges the surface of the photoconductor 2 to a uniform high potential. Next, the exposure device 6 exposes the surface of each photoconductor 2 based on the image information of the original document read by the document reading device or the print information instructed to be printed from the terminal. This reduces the potential of the exposed area, forming an electrostatic latent image. Toner is then supplied from the developing device 4 to this electrostatic latent image, and a toner image is formed on each photoconductor 2.

[0019] The toner images formed on each photoconductor 2 rotate with the rotation of the photoconductor 2 and reach the primary transfer nip (the position of the primary transfer roller 12). The toner images are then transferred to the intermediate transfer belt 11, which rotates counterclockwise in FIG. 1, so that they overlap one another. The toner images transferred onto the intermediate transfer belt 11 are then transported to the secondary transfer nip (the position of the secondary transfer roller 13) with the rotation of the intermediate transfer belt 11. The toner images are then transferred to the paper P transported at the secondary transfer nip. This paper P is supplied from the paper feeder 7. The paper P supplied from the paper feeder 7 is temporarily stopped by timing roller 15 and then transported to the secondary transfer nip in time with the toner image on the intermediate transfer belt 11 reaching the secondary transfer nip. In this way, a full-color toner image is carried on the paper P. After the toner image is transferred, any toner remaining on each photoconductor 2 is removed by the cleaning devices 5.

[0020] The paper P onto which the toner image has been transferred is transported to a fixing device 9, which fixes the toner image onto the paper P. The paper P is then discharged outside the apparatus by a paper discharge device 10, completing the series of printing operations.

[0021] Next, the configuration of the fixing device will be described.

[0022] As shown in FIG. 2, the fixing device 9 according to this embodiment includes a fixing belt 20, a pressure roller 21 as a counter rotating member or pressure member, a heater 22 as a heating element, a heater holder 23 as a holding member, a stay 24, a thermistor 25 as a temperature detection member, a first high thermal conductivity member 28, and a conductive member 40. The fixing belt 20 is an endless belt. The pressure roller 21 contacts the outer peripheral surface of the fixing belt 20 to form a fixing nip N between the fixing belt 20 and the pressure roller 21. The heater 22 heats the fixing belt 20. The heater holder 23 holds the heater 22. The stay 24 supports the heater holder 23. The thermistor 25 detects the temperature of the first high thermal conductivity member 28.

[0023] The direction perpendicular to the plane of FIG. 2 is the longitudinal direction of the fixing belt 20, pressure roller 21, heater 22, heater holder 23, stay 24, first high-thermal-conductivity member 28, etc., and corresponds to the direction of the double-headed arrow X shown in FIG. 4 and other figures. Hereinafter, this direction will be referred to simply as the longitudinal direction. This longitudinal direction also corresponds to the width direction of the paper being conveyed, the belt width direction of the fixing belt 20, and the axial direction of the pressure roller 21. The direction of arrow A in FIG. 2 is the paper conveyance direction. Hereinafter, the upstream side in the paper conveyance direction, which is the lower side in FIG. 2, will be simply referred to as the upstream side, and the downstream side in the paper conveyance direction, which is the upper side in FIG. 2, will be simply referred to as the downstream side. The fixing member provided in the fixing device is one example of a rotating member provided in the heating device of the present invention. The fixing device 9 of this embodiment is provided with a fixing belt 20 as a specific example of this fixing member. The stay 24 is one example of a first opposing member provided in the heating device of the present invention and is also a support member that supports the holding member.

[0024] The fixing belt 20 has a base layer made of a cylindrical substrate made of polyimide (PI) having an outer diameter of 25 mm and a thickness of 40 to 120 μm. A release layer made of a fluororesin such as PFA or PTFE and having a thickness of 5 to 50 μm is formed on the outermost surface of the fixing belt 20 to enhance durability and ensure releasability. A 50 to 500 μm thick elastic layer made of rubber or the like may be provided between the substrate and the release layer. The fixing belt 20 of this embodiment is a rubberless belt that does not have an elastic layer. The substrate of the fixing belt 20 is not limited to polyimide, and may be a heat-resistant resin such as PEEK or a metal substrate such as nickel (Ni) or SUS. The inner peripheral surface of the fixing belt 20 may be coated with a sliding layer made of polyimide, PTFE, or the like.

[0025] The pressure roller 21 has an outer diameter of, for example, 25 mm and is composed of a solid iron core 21a, an elastic layer 21b formed on the surface of the core 21a, and a release layer 21c formed on the outside of the elastic layer 21b. The elastic layer 21b is made of silicone rubber and has a thickness of, for example, 3.5 mm. To improve the release properties of the surface of the elastic layer 21b, it is desirable to form the release layer 21c, which is a fluororesin layer having a thickness of, for example, about 40 μm.

[0026] The pressure roller 21 is urged toward the fixing belt 20 by the urging means, so that the pressure roller 21 is pressed against the heater 22 via the fixing belt 20. As a result, a fixing nip N is formed between the fixing belt 20 and the pressure roller 21. The pressure roller 21 is configured to be rotationally driven by a driving means, and when the pressure roller 21 rotates in the direction of the arrow in FIG. 2, the fixing belt 20 is accordingly rotated in the direction of the arrow J.

[0027] The heater 22 is disposed so as to be in contact with the inner circumferential surface of the fixing belt 20. In this embodiment, the heater 22 is in contact with the pressure roller 21 via the fixing belt 20, and serves as a nip forming member that forms a fixing nip N between the heater 22 and the pressure roller 21. The fixing belt 20 is also a member to be heated by the heater 22.

[0028] The heater 22 is a planar heating element provided longitudinally across the width direction of the fixing belt 20. The heater 22 is composed of a plate-shaped base material 30, a resistance heating element 31 provided on the base material 30, an insulating layer 32 covering the resistance heating element 31, and the like. When an AC voltage is applied to the heater 22 from a power source 200 (see FIG. 22 ), the resistance heating element 31 mainly generates heat, thereby heating the fixing belt 20.

[0029] Furthermore, the heater 22 is in contact with the inner circumferential surface of the fixing belt 20 on the insulating layer 32 side, and heat generated by the resistance heating element 31 is transferred to the fixing belt 20 via the insulating layer 32. However, this contact may be via a conductive member such as a sliding sheet. In this embodiment, the resistance heating element 31 and the insulating layer 32 are provided on the fixing belt 20 side (the fixing nip N side) of the substrate 30. However, the resistance heating element 31 and the insulating layer 32 may be provided on the heater holder 23 side of the substrate 30. In this case, since heat from the resistance heating element 31 is transferred to the fixing belt 20 via the substrate 30, it is desirable that the substrate 30 be made of a material with high thermal conductivity, such as aluminum nitride. Furthermore, by forming the substrate 30 from a material with high thermal conductivity, the fixing belt 20 can be sufficiently heated even if the resistance heating element 31 is disposed on the opposite side of the substrate 30 from the fixing belt 20 side.

[0030] When the fixing belt 20 rotates, the inner peripheral surface of the fixing belt 20 comes into sliding contact with the heater 22 at the position of the fixing nip N. For this reason, in order to reduce the frictional resistance between the fixing belt 20 and the heater 22, a lubricant such as grease is applied to the sliding contact surface of the heater 22. This makes it possible to suppress wear of the fixing belt 20.

[0031] The heater holder 23 and the stay 24 are disposed on the inner circumferential side of the fixing belt 20. The stay 24 is made of a metal channel material, and both longitudinal ends thereof are supported by both side plates of the fixing device 9. By supporting the heater holder 23 and the heater 22 by the stay 24, the heater 22 can reliably receive the pressing force of the pressure roller 21 when the pressure roller 21 is pressed against the fixing belt 20. This ensures that the fixing nip N is stably formed between the fixing belt 20 and the pressure roller 21. In this embodiment, the thermal conductivity of the heater holder 23 is set to be smaller than that of the base material 30.

[0032] The stay 24 has a generally U-shaped configuration with vertical portions 24a serving as walls on both the upstream and downstream sides in the paper transport direction. The vertical portions 24a abut against the heater holder 23 at their end faces and also support the heater holder 23. The vertical portions 24a extend in the left-right direction in FIG. 2, which is the pressure direction of the pressure roller 21. The stay 24 is also grounded via a resistor 41.

[0033] In this embodiment, the stay 24 supports the heater holder 23 by abutting a portion extending in the pressure direction of the pressure roller 21 (left-right direction in the figure) or a thick portion against the heater holder 23 from the opposite side of the pressure roller 21 (left side in the figure). This makes it possible to suppress deflection of the heater holder 23 due to the pressure from the pressure roller 21 (particularly deflection in the longitudinal direction in this embodiment). However, the above-mentioned contact of the stay 24 with the heater holder 23 is not limited to cases where the stay 24 is in direct contact with the heater holder 23, but also includes cases where the stay 24 is in contact via another member. "Contact via another member" refers to a state in which another member is sandwiched between the stay 24 and the heater holder 23 in the left-right direction in the figure, and the stay 24 is in contact with the other member and the other member is in contact with the heater holder 23 at a position where at least a portion of the other member corresponds to the other member. Furthermore, the term "extending in the pressure direction" mentioned above does not necessarily mean the same direction as the pressure direction of the pressure roller 21, but also includes the case of extending in a direction at a certain angle from the pressure direction of the pressure roller 21. Even in these cases, it goes without saying that the stay 24 can suppress the deflection of the heater holder 23 against the pressure force from the pressure roller 21.

[0034] The heater holder 23 is desirably made of a heat-resistant material because it is prone to becoming hot due to the heat from the heater 22. For example, if the heater holder 23 is made of a heat-resistant resin with low thermal conductivity, such as LCP or PEEK, heat transfer from the heater 22 to the heater holder 23 is suppressed. This allows the heater 22 to heat the fixing belt 20 efficiently.

[0035] Heater holder 23 has recess 23b for holding first high thermal conductivity member 28 and heater 22 (see FIG. 29).

[0036] 2, the heater holder 23 is integrally provided with guide portions 26 that guide the fixing belt 20. The guide portions 26 are provided on the upstream and downstream sides of the heater holder 23 in the paper transport direction.

[0037] The guide portion 26 is provided with a plurality of guide ribs 260 as guide members. The guide ribs 260 are formed in a generally fan shape. The guide ribs 260 are provided along the inner circumferential surface of the fixing belt 20 and have arc-shaped or convex-curved guide surfaces 260a extending in the circumferential direction of the belt.

[0038] Heater holder 23 has an opening 23a penetrating through it in the thickness direction. A thermistor 25 and a thermostat (described later) are provided in this opening 23a. The thermistor 25 and the thermostat are pressed by a spring and pressed against the back surface of first high thermal conductivity member 28. However, openings may also be similarly provided in first high thermal conductivity member 28 and a second high thermal conductivity member (described later), so that the thermistor 25 and the thermostat are pressed against the back surface of base material 30.

[0039] The first high thermal conductivity member 28 is made of a material having a higher thermal conductivity than the base material 30. In this embodiment, the first high thermal conductivity member 28 is made of plate-shaped aluminum. Alternatively, the first high thermal conductivity member 28 may be made of, for example, copper, silver, graphene, or graphite. By making the first high thermal conductivity member 28 plate-shaped, the positional accuracy of the heater 22 with respect to the heater holder 23 and the first high thermal conductivity member 28 can be improved.

[0040] Next, a method for calculating the thermal conductivity will be described. When calculating the thermal conductivity, first, the thermal diffusivity of the object is measured, and then the thermal conductivity is calculated using the measured thermal diffusivity.

[0041] The thermal diffusivity was measured using a thermal diffusivity / thermal conductivity measuring device (trade name: ai-Phase Mobile 1u, ai-Phase Corporation).

[0042] To convert the thermal diffusivity to thermal conductivity, the density and specific heat capacity values ​​are required. A dry-type automatic densitometer (product name: Accupyc 1330, manufactured by Shimadzu Corporation) was used to measure the density. A differential scanning calorimeter (product name: DSC-60, manufactured by Shimadzu Corporation) was used to measure the specific heat capacity, using sapphire as a reference material with a known specific heat capacity. In this example, the specific heat capacity was measured five times, and the average value at 50°C was used. When the density and specific heat capacity are ρ and C, respectively, the thermal conductivity λ can be calculated from the thermal diffusivity α obtained from the thermal diffusivity measurement using the following equation (1):

[0043]

number

[0044] In the fixing device 9 according to this embodiment, when a printing operation is started, the pressure roller 21 is driven to rotate, and the fixing belt 20 starts to rotate in response. At this time, the inner circumferential surface of the fixing belt 20 contacts and is guided by the guide surface 260a of the guide rib 260, thereby allowing the fixing belt 20 to rotate stably and smoothly. Furthermore, power is supplied to the resistance heating element 31 of the heater 22, thereby heating the fixing belt 20. Then, when the temperature of the fixing belt 20 reaches the fixing temperature, which is a predetermined target temperature, as shown in FIG. 2 , a sheet of paper P carrying an unfixed toner image is conveyed to the fixing nip N between the fixing belt 20 and the pressure roller 21, whereby the unfixed toner image is heated and pressurized and fixed to the sheet of paper P.

[0045] However, this type of fixing device 9 has the problem of image banding. Specifically, in a fixing device 9 that applies an AC voltage to the heater 22, the insulating layer on the heater 22 and the surface layer of the fixing belt 20 are equivalent to a capacitor. When the heater 22 and the fixing belt 20 come into contact with each other, an AC voltage is applied to the fixing nip N via the fixing belt 20. As shown in FIG. 3 , when a sheet of paper P is in contact with both the secondary transfer nip NA and the fixing nip N, this AC voltage propagates through the sheet of paper P to the secondary transfer nip NA as indicated by the arrow in FIG. 3 . This AC voltage affects the transfer electric field, causing periodic density variations in the transferred image, resulting in so-called image banding. This problem becomes particularly pronounced when the sheet of paper P has low resistance, such as in a high-humidity environment or when thin paper is used as the sheet of paper P. The secondary transfer nip NA is a nip formed between the secondary transfer roller 13 and the secondary transfer counter roller 16.

[0046] Furthermore, in such a fixing device 9, image defects may occur due to electrostatic offset. That is, when the paper P passes through the fixing nip N, unfixed toner on the paper P is attracted to the charged surface of the fixing belt 20, and the unfixed toner adheres to the fixing belt 20. Then, as the fixing belt 20 rotates, the adhered toner moves again toward the fixing nip N, and this toner adheres to the paper P that reaches the fixing nip N after the aforementioned paper. This toner adhesion causes image defects.

[0047] Therefore, in this embodiment, by providing the aforementioned conductive member 40 in the fixing device 9, the AC voltage can be passed from the fixing nip N to the fixing belt 20 and then to the ground side via the conductive member 40. This prevents the formation of the above-mentioned banding image. Furthermore, by providing the conductive member 40, the charge on the surface of the fixing belt 20 is removed, preventing image defects due to the above-mentioned electrostatic offset.

[0048] The conductive member 40 is sheet-shaped. The conductive member 40 is made of a conductive material, and in this embodiment, is made of conductive polyimide with added carbon black. The conductive member 40 is grounded via the stay 24 and a resistor 41. There may be multiple conductive members 40 provided in the longitudinal direction, or just one conductive member 40. The conductive member 40 is disposed between the stay 24 and the guide portion 26.

[0049] The conductive member 40 has a free end 40a, which is a contact portion that contacts the inner surface of the fixing belt 20. The contact of the one end 40a with the inner surface of the fixing belt 20 allows the charge on the surface of the fixing belt 20 to be released to ground via the stay 24 and the resistor 41, thereby removing the charge accumulated on the surface of the fixing belt 20. In this embodiment, the side of the conductive member 40 opposite the one end 40a is referred to as the other end 40b. The terms "one end 40a" and "other end 40b" simply refer to the side of the one end 40a or the other end 40b relative to the center of the length of the conductive member 40 along the surface of the conductive member 40 in a direction perpendicular to its width. In other words, if the conductive member 40 is not bent and is in a substantially sheet-like shape, the side of the one end 40a or the other end 40b relative to the center of the length of the conductive member 40 along the surface of the conductive member 40 in a direction perpendicular to its width is also referred to as the side of the one end 40a or the other end 40b relative to the center of the length of the conductive member 40 along the surface of the conductive member 40 in a direction perpendicular to its width.

[0050] In this embodiment, the facing portion 40c of the conductive member 40 faces the first facing surface 24d of the stay 24 serving as a first facing member, and the facing portion 40c is fixed to the vertical portion 24a by a screw 42 serving as a fixing member. The vertical portion 24a of the stay 24 is provided with a fastening hole 24b for fixing the screw 42.

[0051] By fixing the facing portion 40c to the stay 24 with the screws 42, the facing portion 40c can be provided along the first facing surface 24d. That is, in this embodiment, the facing portion 40c, including the portion of the facing portion 40c fixed by the screws 42, is provided along the first facing surface 24d. Therefore, the contact position and posture of the one end 40a of the conductive member 40 with the inner surface of the fixing belt 20 can be stabilized. Furthermore, the contact pressure of the conductive member 40 with the inner surface of the fixing belt 20 can be ensured. Therefore, the contact state of the conductive member 40 with the inner surface of the fixing belt 20 can be stabilized.

[0052] In addition, in this embodiment, the conductive member 40 can be reliably brought into contact with the stay 24 and can be grounded via the stay 24 .

[0053] The position where the conductive member 40 is fixed by the screw 42, i.e., the position where the fastening hole 24b is provided, is located closer to the one end 40a of the conductive member 40 than the center of the first opposing surface 24d in the left-right direction in FIG. 2. In other words, when the fixing belt 20 is divided into two in the up-down direction in FIG. 2, which is the paper conveyance direction, or in the left-right direction in FIG. 2, which is a direction perpendicular to this direction and different from the longitudinal direction, the position where the conductive member 40 is fixed by the screw 42 is located on the same side as the one end 40a. In particular, in this embodiment, regardless of the direction in which the fixing belt 20 is divided into two, the position where the conductive member 40 is fixed by the screw 42 is located on the same side as the one end 40a. In this manner, in this embodiment, the opposing portion 40c is fixed to the first opposing surface 24d at a position closer to the position where the conductive member 40 contacts the fixing belt 20. This allows for more stable posture of the conductive member 40 and its contact with the inner surface of the fixing belt 20.

[0054] By the way, the lubricant applied between heater 22 and the inner circumferential surface of fixing belt 20 is carried downstream in the rotation direction along the surface of fixing belt 20 as fixing belt 20 rotates. At this time, conductive member 40 comes into contact with the inner circumferential surface of fixing belt 20, and as a result, conductive member 40 scrapes off the lubricant applied to the inner circumferential surface of fixing belt 20. If a large amount of lubricant is scraped off by conductive member 40, the frictional resistance between the inner circumferential surface of fixing belt 20 and heater 22 increases, causing abnormal wear of fixing belt 20.

[0055] The configuration of this embodiment, which prevents the conductive member 40 from scraping off the lubricant, will be described below.

[0056] FIG. 4 is a view of the conductive member 40 as viewed from above in FIG. One end 40a of the conductive member 40 shown in FIG. 4 is a contact portion that contacts the inner circumferential surface of the fixing belt 20. Hereinafter, the one end 40a will also be referred to as the contact portion 40a. The contact portion 40a has a tapered shape that narrows toward the edge. In particular, the contact portion 40a of this embodiment has a pointed end shape. By forming the contact portion 40a as a pointed end, the area of ​​the contact portion 40a that contacts the fixing belt 20 can be minimized. This minimizes scraping of the lubricant by the contact portion 40a, preventing abnormal wear of the fixing belt 20. Furthermore, by forming the contact portion 40a as a pointed end, the contact pressure of the conductive member 40 with the fixing belt 20 can be increased, stabilizing the contact state of the conductive member 40 with the fixing belt 20.

[0057] In this way, the protruding end formed on the contact portion 40a is a limiting portion that limits the portion of the conductive member 40 that comes into contact with the inner circumferential surface of the fixing belt 20, and limits the contact range. "Limiting the contact range" here means, for example, making the contact width of the contact portion 40a with the fixing belt 20 smaller than the width X1 of the base end portion, which is the portion of the conductive member 40 on the other end side than the contact portion 40a, or dividing the contact point into multiple portions and reducing the contact range per point.

[0058] Also, by making the width of the contact portion 40a smaller than the width of the base end, in other words by providing the contact portion 40a inside the width X1, it is possible to reduce the size of the conductive member 40. Furthermore, since the portion of the conductive member 40 that actually comes into contact with the fixing belt 20 can be provided closer to the base end, it is possible to stabilize the contact state of the conductive member 40 with the fixing belt 20.

[0059] However, the configuration of the limiting portion provided on the contact portion 40a of the conductive member 40 is not limited thereto. For example, as shown in FIG. 5(a), the contact portion 40a may have a small flat portion at the tip, or as shown in FIG. 5(b), the contact portion 40a may have a curved shape at the tip. Note that the contact portions 40a in FIGS. 5(a) and 5(b) are similar to the contact portion 40a in FIG. 4 in that they taper toward the tip. Furthermore, as shown in FIGS. 6(a), 6(b), and 6(c), the shape of these contact portions 40a may include a slit 405. The slit 405 is provided at the center of the width of the conductive member 40. By providing the slit 405 in the contact portion 40a, the area of ​​contact of the contact portion 40a with the inner circumferential surface of the fixing belt 20 can be divided by the slit 405, thereby reducing the amount of lubricant scraped off by the contact portion 40a.

[0060] As shown in FIG. 7 , the contact portion 40a of this embodiment has a limiting portion, which has an uneven shape in the width direction of the conductive member 40, consisting of multiple protrusions and recesses that are recessed from the protrusions toward the other end 40b of the conductive member 40. By providing the unevenness on the contact portion 40a in this manner, the contact portion 40a can separate the contact points of the contact portion 40a with the inner circumferential surface of the fixing belt 20 into multiple locations, thereby reducing the contact area with the fixing belt 20. This reduces the likelihood of the contact portion 40a scraping away the lubricant. Furthermore, since the contact portion 40a contacts the inner circumferential surface of the fixing belt 20 at multiple locations, the conductive member 40 can more stably neutralize the fixing belt 20 compared to when the contact portion 40a contacts the inner circumferential surface of the fixing belt 20 at only one location. For example, in a configuration in which the contact portion 40a contacts the inner circumferential surface of the fixing belt 20 at only one location, such as the contact portion 40a in FIG. 4 , there is a risk that the lubricant may be interposed between the contact portion 40a and the fixing belt 20, hindering the contact of the contact portion 40a with the inner surface of the fixing belt 20. Therefore, the contact portion 40a comes into contact with the inner circumferential surface of the fixing belt 20 at a plurality of points, so that the conductive member 40 can stably neutralize the fixing belt 20.

[0061] 8, the contact portion 40a can be provided with a plurality of slits 405 as limiting portions. This allows the contact area of ​​the contact portion 40a with the inner circumferential surface of the fixing belt 20 to be divided into multiple areas, compared to a rectangular contact portion 40a without limiting portions, and makes it possible to prevent the contact portion 40a from scraping away the lubricant. Furthermore, the contact portion 40a can come into contact with the inner circumferential surface of the fixing belt 20 at multiple points, allowing the conductive member 40 to stably neutralize the fixing belt 20.

[0062] 9 has a bent portion 40g, which is bent by plastic deformation in the direction opposite to the rotation direction of the fixing belt, on the side of the contact portion 40a. The bent portion 40g is formed, for example, before the conductive member 40 is assembled into the fixing device 9 or before the fixing belt 20 is assembled into the fixing device 9. By providing the bent portion 40g, the contact portion 40a of the conductive member 40 can be brought into contact with the inner surface of the fixing belt 20 more stably.

[0063] In this embodiment, as shown in FIGS. 4 and 10 , the screws 42 are disposed between the guide ribs 260 in the longitudinal direction, i.e., the left-right direction in FIG. 4 . That is, the screws 42 are disposed between the guide ribs 260 at positions that do not overlap the guide ribs 260 in the longitudinal direction. This prevents the screws 42 from interfering with the guide ribs 260. If the screws 42 were disposed at positions that overlap the guide ribs 260 in the longitudinal direction, the screws 42 would need to be disposed so that their heads do not interfere with the guide ribs 260, which would increase the diameter of the fixing belt 20. In contrast, with the above-described arrangement of the present embodiment, the screws 42 do not interfere with the guide ribs 260 even when the guide ribs 260 and the screws 42 are disposed at positions that overlap when viewed in a cross section perpendicular to the longitudinal direction, as shown in FIG. 2 . This allows the screws 42 to be disposed compactly within the fixing belt 20, thereby reducing the diameter of the fixing belt 20. This allows the fixing device to be made smaller.

[0064] In particular, in this embodiment, as shown in FIG. 2 , the screw 42 is provided at a position farther from the inner surface of the fixing belt 20 than the guide surface 260a of the guide rib 260. That is, in the radial direction of the fixing belt 20, the screw 42 is provided at a position farther from the inner surface of the fixing belt 20 than the guide surface 260a. Specifically, when comparing a distance R1 in the upward direction in FIG. 2 (the screw 42 insertion direction) from the center of the screw head of the screw 42 to the inner surface of the fixing belt 20, and a distance R2 in the screw 42 insertion direction from the same position on the guide surface 260a as the screw 42, that is, the same position as the center of the screw head in the left-right direction on the guide surface 260a in FIG. 2 , to the inner surface of the fixing belt 20, R1>R2 holds. Alternatively, in the cross section of FIG. 2 on a plane perpendicular to the longitudinal direction of the fixing belt 20, the shortest distance of the screw 42 to the inner surface of the fixing belt 20 is greater than the shortest distance of the guide surface 260a to the inner surface of the fixing belt 20. This prevents the screws 42 from coming into contact with the inner surface of the fixing belt 20, thereby preventing damage to the fixing belt 20 due to contact with the screws 42.

[0065] Next, an embodiment in which a conductive member is arranged without using a fixing member will be described with reference to FIG.

[0066] As shown in FIG. 11 , the conductive member 40 has a facing portion 40c that faces the first facing surface 24d of the stay 24 and the second facing surface 26a of the guide portion 26. The first facing surface 24d and the second facing surface 26a regulate the tilt of the conductive member 40. That is, the first facing surface 24d and the second facing surface 26a are positioned so that they can abut against the conductive member 40 and regulate the tilt of the conductive member 40 when the conductive member 40 tilts upward or downward in FIG. 11 . In particular, in this embodiment, the facing portion 40c is provided adjacent to the first facing surface 24d and the second facing surface 26a. The first facing surface 24d faces a first surface 401, which is the surface of the conductive member 40 opposite to a second surface 402, which is the surface of the conductive member 40 that contacts the fixing belt 20. The second facing surface 26a faces the second surface 402 of the conductive member 40 that contacts the fixing belt 20. 11, the belt rotation direction at the position of one end 40a of the conductive member 40 where it contacts the inner surface of the fixing belt 20 is the direction of arrow J', in this embodiment, the first opposing surface 24d faces the opposing portion 40c from the downstream side of direction J', and the second opposing surface 26a faces the opposing portion 40c from the upstream side of direction J'. In the following description, the side of surface 401 of the conductive member 40 that contacts the fixing belt 20 is also referred to as the "contact side of the conductive member 40," and the side of surface 402 of the conductive member 40 opposite to the surface that contacts the fixing belt 20 is also referred to as the "opposite side to the contact side of the conductive member 40."

[0067] The facing portion 40c faces the first facing surface 24d and the second facing surface 26a and extends along the first facing surface 24d and the second facing surface 26a. However, the facing portion 40c does not necessarily have to be provided along both the first facing surface 24d and the second facing surface 26a. In this embodiment, the first facing surface 24d and the second facing surface 26a are flat portions that extend in a direction substantially parallel to the pressure direction of the pressure roller 21.

[0068] The guide portion 26 is the second opposing member in this embodiment. This second opposing member may be provided integrally with the heater holder 23 as in this embodiment, or may be an independent member. In addition, the second opposing member is not limited to a member having a guide surface 260 that guides the inner surface of the fixing belt 20 as in this embodiment.

[0069] The conductive member 40 has a one-end bent portion 40d adjacent to the facing portion 40c, which is bent toward the first surface 401, opposite the second surface 402 that contacts the conductive member 40. The one-end bent portion 40d is a portion that is bent due to elastic deformation. In the conductive member 40 of this embodiment, the portion from the one-end bent portion 40d to the one end 40a is bent toward the same side, that is, the downstream side in the rotation direction of the fixing belt 20.

[0070] The conductive member 40 is bent at the other end 40b of the facing portion 40c. The other end 40b of the conductive member 40, opposite the one end 40a across the facing portion 40c, is sandwiched between the vertical portion 24a of the stay 24 and the heater holder 23 in the left-right direction in FIG. 11 . This ensures that the conductive member 40 is securely sandwiched between the stay 24 and the heater holder 23 by the pressure of the pressure roller 21. This ensures that the other end 40b of the conductive member 40 is securely positioned relative to the stay 24. Furthermore, the conductive member 40 is securely in contact with the stay 24, allowing for grounding via the stay 24. Furthermore, the conductive member 40 can be held by the stay 24 and the heater holder 23. These effects can be achieved without the need for fixing members such as screws, allowing for a more compact fixing device. Furthermore, the thermal capacity of the fixing device can be reduced, resulting in energy savings.

[0071] If the first opposing surface 24d and the second opposing surface 26a are not disposed opposite the opposing portion 40c of the conductive member 40, variations in the extension direction of the free end 40a of the conductive member 40 occur due to variations in the components of the conductive member 40. For example, when the components are assembled, the conductive member 40 may extend vertically as shown in FIG. 11 , or it may be tilted toward the stay 24 as shown by the dotted line in FIG. 12(a) or toward the guide portion 26 as shown by the dotted line in FIG. 12(b). If the orientation of the conductive member 40 and the contact position with the inner surface of the fixing belt 20 vary in this way, the contact state of the conductive member 40 with the fixing belt 20 becomes unstable.

[0072] However, in this embodiment, by having the first opposing surface 24d facing the conductive member 40 as described above, tilting of the conductive member 40 is restricted, and the opposing portion 40c of the conductive member 40 can be provided along the first opposing surface 24d, as shown in Fig. 12(a). This makes it possible to suppress variations in the contact position and contact posture of the conductive member 40 with the fixing belt 20, and to stabilize the contact state with the inner surface of the fixing belt 20.

[0073] Furthermore, by providing the first opposing surface 24d and maintaining the opposing portion 40c of the conductive member 40 in a shape that rises along the first opposing surface 24d, contact pressure between the conductive member 40 and the inner surface of the fixing belt 20 can be ensured, thereby stabilizing the contact state of the conductive member 40 with the inner surface of the fixing belt 20. That is, the conductive member 40 contacts the inner surface of the fixing belt 20 at one end 40a and bends in the direction of arrow J, which is the belt rotation direction. In particular, when the fixing belt 20 rotates, the one end 40a of the conductive member 40 receives a rotational force from the fixing belt 20 in the direction of arrow J. Therefore, the conductive member 40 has a one-end bent portion 40d bent in the belt rotation direction between the one end 40a and the central portion of the opposing portion 40c, which is maintained in a raised shape. The stress generated by this one-end bent portion 40d, i.e., the force of the one-end bent portion 40d attempting to elastically return, ensures contact pressure between the one end 40a of the conductive member 40 and the inner surface of the fixing belt 20. Therefore, the state of contact between the conductive member 40 and the inner surface of the fixing belt 20 can be stabilized.

[0074] As described above, by stabilizing the contact state of the conductive member 40 with the inner surface of the fixing belt 20, the AC voltage applied to the fixing nip N can be stably released to the ground side via the fixing belt 20. This prevents the aforementioned banding images. The electric charge accumulated in the fixing belt 20 can be stably released to the ground side via the stay 24. This prevents image defects due to electrostatic offset. Furthermore, these effects can be achieved without fixing the conductive member 40 to a predetermined component within the fixing device with a fixing member such as a screw. This eliminates the need for space for fixing members such as screws, allowing the fixing device to be made smaller. Furthermore, the thermal capacity of the fixing device can be reduced, resulting in energy savings.

[0075] In this embodiment, the one end 40a, which is the contact portion of the conductive member 40, contacts the fixing belt 20 at a position beyond the first opposing surface 24d of the stay 24. That is, the one end 40a of the conductive member 40 is disposed on the opposite side of the first opposing surface 24d from the opposing portion 40c. The "opposite side of the first opposing surface" refers to the conductive member 40 being disposed on one side and the other side of the boundary of an extension plane L (see FIG. 11 ) of the first opposing surface 24d. The "first opposing surface" in the "opposite side of the first opposing surface" refers to the surface of the conductive member 40 facing the portion of the conductive member 40 opposite the one end 40a across the one-end bent portion 40d. In this embodiment, this refers to the surface facing the opposing portion 40c, including the portion adjacent to the one-end bent portion 40d. This arrangement ensures contact pressure between the conductive member 40 and the inner surface of the fixing belt 20, thereby stabilizing the contact state of the conductive member 40 with the inner surface of the fixing belt 20.

[0076] In particular, in this embodiment, a portion of the conductive member 40 abuts against the stay 24, and the portion of the conductive member 40 on the one end 40a side from the abutting portion is bent downstream in the rotation direction of the fixing belt 20. In other words, by abutting against the stay 24, the conductive member 40 is supported by the stay 24 from the side opposite the rotation direction J of the fixing belt 20. The portion of the conductive member 40 on the one end 40a side from the abutting portion, or the portion of the conductive member 40 on the one end 40a side including the abutting portion, is bent downstream in the rotation direction J. By bending the side of the conductive member 40 that contacts the inner surface of the fixing belt 20 in this manner, the contact pressure of the conductive member 40 with respect to the inner surface of the fixing belt 20 can be ensured, as described above, and the contact state can be stabilized.

[0077] Furthermore, in this embodiment, the second opposing surface 26a faces the opposing portion 40c of the conductive member 40 on the contact side of the conductive member 40, thereby preventing the conductive member 40 from tilting as shown in FIG. 12(b), and the opposing portion 40c of the conductive member 40 can be arranged along the second opposing surface 26a. This reduces variations in the contact position and contact posture of the conductive member 40 with the fixing belt 20, thereby stabilizing the contact state of the conductive member 40 with the inner surface of the fixing belt 20. In this way, by providing members facing the conductive member 40 on both sides of the fixing belt 20 in the rotation direction, the opposing portion 40c of the conductive member 40 can be arranged between the first opposing surface 24d and the second opposing surface 26a. This particularly stabilizes the posture of the conductive member 40, thereby stabilizing the contact state of the conductive member 40 with the inner surface of the fixing belt 20. The inclination of the conductive member 40 referred to here refers to the inclination in the vertical direction in Figure 11, or in other words, the inclination in the thickness direction of the conductive member 40, or the inclination in the direction in which the conductive member 40 contacts the first opposing surface 24d or the second opposing surface 26a.

[0078] In this embodiment, the phrase "a portion of the conductive member is provided along" the first opposing surface or the second opposing surface includes cases where the conductive member is completely parallel to the first opposing surface or the second opposing surface, as well as cases where the conductive member is slightly inclined. In other words, it is sufficient if the shape of the opposing portion of the conductive member can be regulated to an extent that the contact position and contact posture of the conductive member with the rotating member are stabilized. Furthermore, this "provided along" refers to cases where the conductive member is provided close to the first opposing surface or the second opposing surface, and of course does not include cases where the conductive member is located at a position far enough away that it does not contact the first opposing surface or the second opposing surface even if the conductive member is inclined.

[0079] 12(a) and 12(b) due to component variations in the conductive member 40 during assembly, but variations in the posture of the conductive member 40 are not limited to this. As an example, even if a predetermined force acts on the conductive member 40 after the components of the fixing device 9 are assembled, causing a force to act on the one end 40a in the direction shown in FIG. 12(a) or 12(b), the first opposing surface 24d or the second opposing surface 26a of this embodiment can suppress the tilt of the conductive member 40 and stabilize the contact state of the conductive member 40 with the inner surface of the fixing belt 20.

[0080] In particular, in this embodiment, the first opposing surface 24d and the second opposing surface 26a are parallel surfaces extending in a direction substantially parallel to the pressure direction of the pressure roller 21. This allows the opposing portion 40c of the conductive member 40 to be maintained in a vertically rising shape between the first opposing surface 24d and the second opposing surface 26a, thereby particularly stabilizing the contact state of the conductive member 40 with the inner surface of the fixing belt 20. The direction does not necessarily have to be parallel to the pressure direction. Furthermore, the "parallel surfaces" referred to here do not necessarily have to be strictly parallel; some degree of error is acceptable. Even in these cases, it goes without saying that the opposing portion 40c can be maintained in a substantially vertically rising shape. Furthermore, either the first opposing surface 24d or the second opposing surface 26a may be configured with a flat portion extending in one direction. This allows the opposing portion 40c to be maintained in a rising shape along this flat portion. Furthermore, this flat portion extending in one direction does not have to be strictly unidirectional; it may have some inclination or unevenness.

[0081] Furthermore, in this embodiment, the conductive member 40 is provided between the stay 24 and the downstream guide rib 260, but it may be disposed between the stay 24 and the upstream guide rib 260. In this case, the facing portion 40c of the conductive member 40 faces a first facing surface of the upstream guide rib 260, which is a first facing member, and a second facing surface of the stay 24, which is a second facing member.

[0082] Furthermore, this conductive member 40 is preferably applied to a fixing device 9 having a fixing belt 20 that does not have an elastic layer, as in this embodiment. This type of fixing belt 20 has less flexibility than a fixing belt 20 having an elastic layer, making it more difficult to form a stable contact state between the fixing belt 20 and the conductive member 40. By applying the conductive member 40 to this type of fixing device 9, the conductive member 40 can be brought into stable contact with the fixing belt 20.

[0083] Furthermore, if the fixing belt 20 has a non-conductive elastic layer, this elastic layer also functions as a capacitor, similar to the insulating layer of the heater 22, making the above-mentioned banding image more likely to occur. Therefore, by not including a non-conductive elastic layer in the fixing belt 20, the problem of banding images can be suppressed.

[0084] Further, another embodiment of the method of attaching the conductive member 40 to the stay 24 will be described with reference to FIGS.

[0085] 13, in this embodiment, a locking hole 24c serving as an opening is provided in the stay 24. The locking hole 24c is a hole portion that extends in a direction intersecting the extending direction of the first opposing surface 24d of the stay 24, and in this embodiment, in particular, extends in the up-down direction perpendicular to the left-right direction in FIG.

[0086] The other end 40b of the conductive member 40 is bent and inserted into the locking hole 24c, thereby attaching the conductive member 40 to the stay 24. However, the member provided with the locking hole is not limited to the stay.

[0087] As shown in FIG. 14, the conductive member 40 of this embodiment is disposed at a position facing the guide rib 260 in the longitudinal direction.

[0088] As shown in FIG. 15, the conductive member 40 has a narrow portion 40j, which is narrower than the remaining portion of the conductive member 40, closer to one end 40a than the other end 40b. By elastically deforming the conductive member 40, the conductive member 40 is inserted into the locking hole 24c of the stay 24 from the other end 40b side. As a result, as shown in FIG. 16, the narrow portion 40j is positioned within the locking hole 24c, and the other end 40b side of the conductive member 40 is locked in the locking hole 24c. This allows the other end 40b side of the conductive member 40 to be reliably positioned relative to the stay 24. Furthermore, these effects can be achieved without the need for fixing members such as screws.

[0089] Then, one end 40a of the conductive member 40 in FIG. 16 is bent as shown in FIG. 13 to form the other end bent portion 40f, and the facing portion 40c is disposed between the first facing surface 24d and the second facing surface 260c.

[0090] In this embodiment, the facing portion 40c of the conductive member 40 faces the first facing surface 24d of the stay 24 and the second facing surface 260c of the downstream guide rib 260, which is the second facing member, and is provided along these surfaces. This stabilizes the contact state between the conductive member 40 and the fixing belt 20, as in the previous embodiment. Furthermore, this effect can be achieved without fixing the conductive member 40 to a predetermined member within the fixing device with a fixing member such as a screw. Therefore, no space is required for fixing members such as screws, and the fixing device can be made smaller. Furthermore, the thermal capacity of the fixing device can be reduced, resulting in energy savings.

[0091] In particular, in this embodiment, an other-end bent portion 40f is formed by elastic deformation so that the other end 40b of the conductive member 40 can be inserted into the locking hole 24c. The other-end bent portion 40f is a portion bent toward the surface of the conductive member 40 opposite to the surface that contacts the fixing belt 20. In other words, the other-end bent portion 40f is a portion bent toward the downstream side in the rotation direction of the fixing belt 20 at the position of the one end 40a. The other-end bent portion 40f is provided on the opposite side of the one end 40a of the conductive member 40, across the opposing portion 40c.

[0092] If the second opposing surface 260c were not disposed on the contact side of the conductive member 40, the conductive member 40 would likely extend in the opposite direction to the insertion direction into the locking hole 24c. For example, the conductive member 40 may extend in the direction indicated by the dotted line in FIG. 13 . The direction of extension of the conductive member 40 may vary depending on how the conductive member 40 is inserted into the locking hole 24c. In contrast, by providing the second opposing surface 260c as in this embodiment, the inclination of the opposing portion 40c toward the contact side can be restricted, and the opposing portion 40c can be positioned along the second opposing surface 260c. This stabilizes the contact state between the conductive member 40 and the fixing belt 20. Furthermore, by having the first opposing surface 24d of the stay 24 facing the opposing portion 40c, the inclination of the conductive member 40 toward the stay 24 side can be restricted, stabilizing the contact state between the conductive member 40 and the fixing belt 20.

[0093] As shown in FIG. 17 , the one end 40a of the conductive member 40 that contacts the fixing belt 20 is preferably located at a position facing the longitudinal center position D of the fixing belt 20 or in the vicinity thereof. At the position where the conductive member 40 contacts the fixing belt 20, sliding resistance occurs between the fixing belt 20 and the conductive member 40. Therefore, if the conductive member 40 is located on only one side of the fixing belt 20 in the longitudinal direction, a difference in sliding resistance occurs between the one side and the other side with respect to the longitudinal center, causing the fixing belt 20 to shift to one side. This can cause damage to the fixing belt 20. Therefore, by locating the conductive member 40 as in this embodiment, damage to the fixing belt 20 due to the shifting of the fixing belt 20 can be prevented. 18, when a plurality of conductive members 40 are arranged, it is preferable that the positions on one side and the other side of the fixing belt 20 where the conductive members 40 come into contact with the inner surface of the fixing belt 20 are approximately symmetrical with respect to the longitudinal center position D, and in particular, that the conductive members 40 be arranged at positions facing the ends of the fixing belt 20 on one side and the other side. This makes it possible to prevent damage to the fixing belt 20 due to deviation of the fixing belt 20. However, the longitudinal arrangement of the conductive members 40 is not limited to this.

[0094] 19, the guide rib 260 may be provided with insertion holes 260b into which the conductive members 40 are inserted. In this embodiment, the opposing portions 40c of the conductive members 40 face first opposing surfaces 260b1 and second opposing surfaces 260b2, which are side wall portions that form the insertion holes 260b. In other words, the guide rib 260 of this embodiment is both the first opposing member and the second opposing member of the present invention.

[0095] However, when a member having an insertion hole is provided in this manner, this member should be made of a conductive material and be grounded. Alternatively, the inner peripheral surface of the insertion hole may be made of a conductive material and this part may be grounded, or this part may be grounded via a stay.

[0096] As in the previously described embodiment, the conductive member 40 faces the first opposing surface 260b1, so that the opposing portion 40c is provided along the first opposing surface 260b1. This stabilizes the contact state of the conductive member 40 with the inner surface of the fixing belt 20. As in the previously described embodiment, the conductive member 40 faces the second opposing surface 260b2, so that the opposing portion 40c is provided along the second opposing surface 260b2. This stabilizes the contact state of the conductive member 40 with the inner surface of the fixing belt 20. These effects can be achieved without fixing the conductive member 40 to a predetermined component within the fixing device with a fixing member such as a screw. This eliminates the need for space for fixing members such as screws, allowing the fixing device to be made smaller. Furthermore, the thermal capacity of the fixing device can be reduced, thereby saving energy.

[0097] In this embodiment, for example, by forming the insertion hole 260b in a shape that narrows toward the back, the other end of the conductive member 40 can be inserted into and held in the insertion hole 260b. Furthermore, the member that provides the insertion hole 260b is not limited to the guide rib, and may be a heater holder that does not have a guide rib or a member dedicated to providing an insertion hole.

[0098] Furthermore, the extending direction of the facing portion 40c of the conductive member 40 is not limited to that of the above embodiment. For example, in the embodiment shown in FIG. 20, the facing portion 40c extends in the vertical direction in FIG. 20. The conductive member 40 is sandwiched between the stay 24 and the heater holder 23. More specifically, the facing portion 40c of the conductive member 40 faces the first facing surface 24e of the stay 24 and the second facing surface 23e of the heater holder 23, and is sandwiched between these surfaces. This allows the facing portion 40c to be provided along the first facing surface 24e or the second facing surface 23e. With this configuration, the contact state between the conductive member 40 and the inner surface of the fixing belt 20 can be stabilized in this embodiment as well.

[0099] 11, 13, 19, and 20, the contact area of ​​the conductive member with the inner surface of the rotating member can be limited by providing the limiting portion as described above, thereby preventing the conductive member from scraping away the lubricant.

[0100] Next, a more detailed configuration of the heater provided in the fixing device will be described with reference to Fig. 21. Fig. 21 is a plan view of the heater according to this embodiment.

[0101] 21, a plurality of (four) resistance heating elements 31, power supply lines 33A and 33B as conductors, and first and second electrode portions 34A and 34B are provided on the surface of a plate-shaped substrate 30. However, the number of resistance heating elements 31 is not limited to that in this embodiment. Hereinafter, the power supply lines 33A and 33B will also be referred to as power supply lines 33, and the first electrode portion 34A or the second electrode portion 34B will also be referred to as electrode portion 34.

[0102] In this embodiment, the longitudinal direction of the heater 22, etc., which is a direction perpendicular to the plane of the paper in FIG. 2, is also the arrangement direction X of the multiple resistance heating elements 31, as shown in FIG. 21. Hereinafter, this direction will also be simply referred to as the arrangement direction. Furthermore, a direction intersecting the arrangement direction, particularly in this embodiment, is a vertical direction, namely, the up-down direction Y in FIG. 21, which is a direction different from the thickness direction of the base material 30, and is also referred to as the direction intersecting the arrangement direction of the multiple resistance heating elements 31, or simply as the intersecting arrangement direction. The intersecting arrangement direction Y is a direction along the surface of the base material 30 on which the resistance heating elements 31 are provided, and is also the widthwise direction of the heater 22 or the transport direction of paper passed through the fixing device 9.

[0103] The multiple resistance heating elements 31 form a heating section 35 divided into multiple sections in the arrangement direction. Each resistance heating element 31 is electrically connected in parallel to a pair of electrode portions 34A, 34B via power supply lines 33A, 33B. The pair of electrode portions 34A, 34B is provided at one end of the substrate 30 in the arrangement direction, i.e., the left end in FIG. 21 . The power supply lines 33A, 33B are made of a conductor with a lower resistance value than the resistance heating elements 31. To ensure insulation between the resistance heating elements 31, the gap between adjacent resistance heating elements 31 is preferably 0.2 mm or more, more preferably 0.4 mm or more. Furthermore, if the gap between adjacent resistance heating elements 31 is too large, a temperature drop is likely to occur in the gap. Therefore, to suppress temperature unevenness across the arrangement direction, the gap is preferably 5 mm or less, more preferably 1 mm or less.

[0104] The resistance heating element 31 is made of a material having a PTC (positive temperature coefficient of resistance) characteristic, and is characterized in that as the temperature rises, the resistance value rises and the heater output decreases.

[0105] The PTC characteristics of the resistance heating element 31 and the divided heating section 35 configuration in the arrangement direction prevent excessive temperature rise of the fixing belt 20 when small-size paper is passed through. In other words, when paper narrower than the overall width of the heating section 35 is passed through, the paper does not absorb heat from the fixing belt 20 in the area outside the paper width, causing the temperature of the resistance heating element 31 corresponding to that area to rise. Because the voltage applied to the resistance heating element 31 is constant, when the temperature of the resistance heating element 31 outside the paper width rises, its resistance value also rises. This results in a relative decrease in heater output, i.e., the amount of heat generated, and suppresses temperature rise at the edge. Furthermore, electrically connecting multiple resistance heating elements 31 in parallel suppresses temperature rise in non-paper passing areas while maintaining printing speed. The heating elements constituting the heating section 35 may be other than resistance heating elements with PTC characteristics. Furthermore, the resistance heating elements may be arranged in multiple rows in the cross-arrangement direction of the heaters 22.

[0106] By dividing the resistance heating element 31 in the arrangement direction in this manner, the temperature rise at the end portions can be suppressed, and temperature unevenness in the arrangement direction of the fixing belt 20 can be suppressed. Because the rigidity of the fixing belt 20 changes depending on its temperature, a fixing belt 20 with less temperature unevenness in the arrangement direction is advantageous in terms of ensuring stable contact with the conductive member 40 described above. Therefore, by adopting the configuration of the resistance heating element 31 divided in the arrangement direction of this embodiment and adopting a configuration in which the first high thermal conductive member 28 and the second high thermal conductive member 36 described below are disposed, stable contact of the conductive member 40 with the fixing belt 20 can be achieved, which is preferable. Furthermore, this is advantageous from the viewpoint of stable contact of the conductive member 40 with the fixing belt 20 even when the conductive member 40 is disposed without using fixing members such as screws.

[0107] The resistance heating element 31 can be formed, for example, by applying a paste made of silver palladium (AgPd) and glass powder to the substrate 30 by screen printing or the like, and then firing the substrate 30. In this embodiment, the resistance value of the resistance heating element 31 is set to 80 Ω at room temperature. In addition to the materials mentioned above, the resistance heating element 31 may also be made of resistance materials such as silver alloy (AgPt) or ruthenium oxide (RuO2). The power supply line 33 and the electrode portion 34 can be made of silver (Ag) or silver palladium (AgPd) by screen printing or the like. The power supply line 33 is made of a conductor with a lower resistance value than the resistance heating element 31.

[0108] The substrate 30 is preferably made of ceramics such as alumina or aluminum nitride, which have excellent heat resistance and insulation properties, or non-metallic materials such as glass or mica. In this embodiment, an alumina substrate is used, which is 8 mm wide in the cross-array direction, 270 mm wide in the array direction, and 1.0 mm thick. Alternatively, the substrate 30 may be made of a conductive material such as a metal laminated with an insulating material. Aluminum and stainless steel are preferred metal materials for the substrate 30, as they are low-cost. By constructing the substrate 30 from a stainless steel plate, cracks due to thermal stress can be suppressed. Furthermore, to improve the thermal uniformity of the heater 22 and enhance image quality, the substrate 30 may be made of a highly thermally conductive material such as copper, graphite, or graphene.

[0109] The insulating layer 32 is made of heat-resistant glass having a thickness of, for example, 75 μm. The insulating layer 32 covers the resistance heating element 31 and the power supply line 33, insulating and protecting them and maintaining sliding properties with the fixing belt 20.

[0110] FIG. 22 is a diagram showing a power supply circuit to the heater according to this embodiment.

[0111] 22, in this embodiment, a power supply circuit for supplying power to each resistance heating element 31 is configured by electrically connecting an AC power supply 200 and the electrodes 34A, 34B of the heater 22. The power supply circuit is also provided with a triac 210 that controls the amount of power supplied. The amount of power supplied to each resistance heating element 31 is controlled by a control unit 220 via the triac 210 based on the temperature detected by the thermistor 25. The control unit 220 is configured by a microcomputer including a CPU, ROM, RAM, I / O interface, etc.

[0112] In this embodiment, thermistors 25 are disposed in a central region in the arrangement direction of heaters 22, which is within the minimum paper passing width, and at one end side in the arrangement direction of heaters 22. Furthermore, at one end side in the arrangement direction of heaters 22, a thermostat 27 is disposed as a power cut-off device that cuts off the supply of power to resistance heating elements 31 when the temperature of resistance heating elements 31 reaches or exceeds a predetermined temperature. Thermistors 25 and thermostat 27 contact first high thermal conductivity member 28 to detect its temperature.

[0113] In this embodiment, the first electrode portion 34A and the second electrode portion 34B are provided on the same side in the arrangement direction, but they may be provided on different sides. The shape of the resistance heating element 31 is not limited to that of this embodiment. For example, as shown in FIG. 23, the resistance heating element 31 may be rectangular, or as shown in FIG. 24, the resistance heating element 31 may be made of a linear portion that is folded back to form a substantially parallelogram shape. As shown in FIG. 23, the portion extending from the block-shaped portion of the resistance heating element 31 toward the power supply line 33 (the portion extending in the intersecting direction) may be part of the resistance heating element 31, or may be made of the same material as the power supply line 33.

[0114] 25A and 25B are diagrams showing the temperature distribution in the arrangement direction of the fixing belt 20. (a) shows the arrangement of the heaters 22. (b) shows the vertical axis representing the temperature T of the fixing belt 20, and the horizontal axis representing each position in the arrangement direction of the fixing belt 20.

[0115] As shown in FIGS. 25(a) and 25(b), the heater 22 has a plurality of resistance heating elements 31 divided in the arrangement direction, forming divided regions B between the resistance heating elements 31. In other words, the heater 22 has a plurality of resistance heating elements 31 arranged at intervals B. Hereinafter, the range B of the divided region will be referred to as interval B. In interval B, the area occupied by the resistance heating elements 31 is smaller than in other regions, resulting in a smaller amount of heat generation. As a result, the temperature of the fixing belt 20 in interval B is lower than in other regions, causing temperature unevenness in the arrangement direction of the fixing belt 20. Furthermore, in an expanded divided region C (hereinafter simply referred to as region C) including the region surrounding interval B, which is a divided region, the temperatures of the heater 22 and the fixing belt 20 are also lower. Note that the temperature of the heater 22 is also lower in interval B. Here, as shown in the enlarged view of FIG. 25(a), interval B refers to the arrangement direction region including all of the regions into which the resistance heating elements 31, which are the main heat-generating portions of the heater 22, are divided in the arrangement direction. Furthermore, an area including the interval B and a range corresponding to the connection portion 311 of the resistance heating element 31 is defined as an area C. The connection portion 311 refers to the portion of the resistance heating element 31 that extends in the cross-arrangement direction and is connected to each of the power supply lines 33A and 33B.

[0116] As shown in Fig. 26, in heater 22 having rectangular resistance heating element 31 as shown in Fig. 23, the temperature in interval B is also lower than in other parts. Also in heater 22 having resistance heating element 31 shaped as shown in Fig. 27, the temperature in interval B is also lower than in other parts. Furthermore, as shown in Fig. 28, in heater 22 having resistance heating element 31 shaped as shown in Fig. 24, the temperature in interval B is also lower than in other parts. However, by overlapping adjacent resistance heating elements 31 in the arrangement direction as in Figs. 25, 27 and 28, the temperature drop in interval B relative to other parts can be suppressed.

[0117] In this embodiment, the above-described first high thermal conductivity member 28 is provided to suppress the temperature drop in the above-mentioned interval and to suppress temperature unevenness in the arrangement direction of the fixing belt 20. The first high thermal conductivity member 28 will be described in more detail below.

[0118] 2, first high thermal conductivity member 28 is disposed between heater 22 and stay 24 in the left-right direction of FIG. 2, and is particularly sandwiched between heater 22 and heater holder 23. That is, first high thermal conductivity member 28 has one surface abutting against the back surface of base material 30 and the other surface abutting against heater holder 23.

[0119] The stay 24 supports the heater holder 23, the first high thermal conductivity member 28, and the heater 22 by bringing the contact surfaces of two vertical portions 24a extending in the thickness direction of the heater 22 etc. into direct contact with the heater holder 23 or by bringing the contact surfaces into contact with the heater holder 23 via the conductive member 40. In the cross-array direction (the vertical direction in FIG. 2), the contact surfaces are provided outside the range in which the resistance heating element 31 is provided. This makes it possible to suppress heat transfer from the heater 22 to the stay 24, and allows the heater 22 to heat the fixing belt 20 efficiently.

[0120] As shown in Fig. 29, first high thermal conductivity member 28 is made of a plate material having a thickness of 0.3 mm, a length in the arrangement direction of 222 mm, and a width in the direction crossing the arrangement of 10 mm. In this embodiment, first high thermal conductivity member 28 is made of a single plate material, but it may be made of multiple members. Note that Fig. 29 omits the illustration of guide portion 26 and guide rib 260 of Fig. 2.

[0121] The first high thermal conductive member 28 is fitted into the recess 23b of the heater holder 23, and the heater 22 is attached thereto, thereby sandwiching and holding the first high thermal conductive member 28 between the heater holder 23 and the heater 22. In this embodiment, the width of the first high thermal conductive member 28 in the arrangement direction is set to be substantially the same as the width of the heater 22 in the arrangement direction. Movement of the first high thermal conductive member 28 and the heater 22 in the arrangement direction is restricted by both side walls (arrangement direction restricting portions) 23b1 in the arrangement direction that form the recess 23b. In this manner, restricting misalignment of the first high thermal conductive member 28 in the arrangement direction within the fixing device 9 improves heat conduction efficiency within a target range in the arrangement direction. Movement of the first high thermal conductive member 28 and the heater 22 in the arrangement direction is restricted by both side walls (arrangement cross direction restricting portions) 23b2 in the arrangement cross direction that form the recess 23b.

[0122] The range in the arrangement direction in which the first high thermal conductivity members 28 are provided is not limited to the above. For example, as shown in FIG. 30, the first high thermal conductivity members 28 may be provided only in the range corresponding to the heat generating portions 35 in the arrangement direction (see the hatched area in FIG. 30). Alternatively, as shown in FIG. 31, the first high thermal conductivity members 28 may be provided only in the entire area at a position corresponding to the interval B in the arrangement direction. Note that for convenience, in FIG. 31, the resistance heating elements 31 and the first high thermal conductivity members 28 are shown shifted in the vertical direction in FIG. 31, but they are actually positioned at approximately the same position in the cross-array direction. However, this is not limiting, and the first high thermal conductivity members 28 may be provided only in a portion of the resistance heating elements 31 in the cross-array direction, or may be provided so as to cover the entire cross-array direction as shown in FIG. 32 described below.

[0123] Furthermore, as shown in Fig. 32, the first high thermal conductivity members 28 may be provided not only at positions corresponding to the interval B in the arrangement direction, but also straddling the resistance heating elements 31 on both sides that sandwich the interval B. "Straddling the resistance heating elements 31 on both sides" means that the first high thermal conductivity members 28 at least partially overlap with the resistance heating elements 31 on both sides in the arrangement direction. Note that the first high thermal conductivity members 28 may be provided to correspond to all of the intervals B of the heaters 22, or may be provided only at positions corresponding to some of the intervals B, such as by providing the first high thermal conductivity members 28 at only one position of the interval B as shown in Fig. 32. Here, "provided at a position corresponding to the interval B in the arrangement direction" means that the first high thermal conductivity members 28 at least partially overlap with the interval B in the arrangement direction.

[0124] Due to the pressure of the pressure roller 21, the first highly thermally conductive member 28 is sandwiched between the heaters 22 and the heater holder 23 and is in close contact with these members. The contact of the first highly thermally conductive member 28 with the heaters 22 improves the thermal conduction efficiency in the arrangement direction of the heaters 22. Furthermore, by providing the first highly thermally conductive member 28 at a position corresponding to the interval B between the heaters 22 in the arrangement direction, the thermal conduction efficiency in the interval B can be improved. This increases the amount of heat transferred to the area of ​​the interval B in the arrangement direction, thereby raising the temperature in the area of ​​the interval B in the arrangement direction. This reduces temperature unevenness in the arrangement direction of the heaters 22. This reduces temperature unevenness in the arrangement direction of the fixing belt 20. This reduces uneven fixing and glossiness of the image fixed on the paper. Alternatively, there is no need for excessive heating by the heaters 22 to ensure sufficient fixing performance in the area of ​​the interval B, thereby achieving energy savings in the fixing device 9. Furthermore, by providing the first high thermal conductivity member 28 over the entire area of ​​the heat generating section 35 in the arrangement direction, the heat transfer efficiency of the heater 22 can be improved over the entire area of ​​the main heating region by the heater 22, i.e., the image forming region of the paper being passed through, and temperature unevenness in the arrangement direction of the heater 22 and therefore the fixing belt 20 can be suppressed.

[0125] In particular, in this embodiment, the combination of the configuration of the first high thermal conductivity member 28 and the resistance heating element 31 having the PTC characteristic described above can effectively suppress excessive temperature rise in the non-paper passing area when small size paper is passed. In other words, the PTC characteristic suppresses the amount of heat generated by the resistance heating element 31 in the non-paper passing area, and the heat of the non-paper passing area with an increased temperature can be efficiently transferred to the paper passing area, effectively suppressing excessive temperature rise in the non-paper passing area.

[0126] Furthermore, it is preferable to arrange first high thermal conductivity members 28 around gap B, since the temperature there is also low due to the small amount of heat generated in gap B. For example, in this embodiment, by providing first high thermal conductivity members 28 at positions corresponding to region C (see FIG. 26), the heat transfer efficiency in the arrangement direction in gap B and its periphery is particularly improved, and temperature unevenness in the arrangement direction of heaters 22 can be further suppressed. Particularly in this embodiment, first high thermal conductivity members 28 are provided over the entire area of ​​heat-generating section 35 in the arrangement direction. This makes it possible to further suppress temperature unevenness in the arrangement direction of heaters 22 (fixing belt 20).

[0127] Next, a different embodiment of the fixing device will be described.

[0128] As shown in FIG. 33, fixing device 9 of this embodiment has second high thermal conductivity member 36 between heater holder 23 and first high thermal conductivity member 28. Second high thermal conductivity member 36 is provided at a different position from first high thermal conductivity member 28 in the left-right direction of FIG. 33, which is the stacking direction of components such as heater holder 23, stay 24, and first high thermal conductivity member 28. More specifically, second high thermal conductivity member 36 is provided overlapping first high thermal conductivity member 28. Note that, unlike FIG. 2, FIG. 33 shows a cross section in which thermistor 25 is not arranged in the arrangement direction. In other words, FIG. 33 shows a cross section in which second high thermal conductivity member 36 is arranged.

[0129] The second high thermal conductivity member 36 is made of a material having a higher thermal conductivity than the base material 30, such as graphene or graphite. In this embodiment, the second high thermal conductivity member 36 is formed of a graphite sheet having a thickness of 1 mm. However, the second high thermal conductivity member 36 may also be formed of a plate material such as aluminum, copper, or silver.

[0130] As shown in Figure 34, a plurality of second high thermal conductive members 36 are arranged in the arrangement direction, each of which is partially provided in the arrangement direction. The portion of recess 23b of heater holder 23 where second high thermal conductive members 36 are provided is one level deeper than the remaining portion. A gap is provided between second high thermal conductive members 36 and heater holder 23 on both sides in the arrangement direction. This suppresses heat transfer from both ends of second high thermal conductive members 36 in the arrangement direction to heater holder 23, allowing heater 22 to efficiently heat fixing belt 20. Note that illustration of guide portion 26 of Figure 2 is omitted in Figure 34.

[0131] 35, second high thermal conductivity members 36 (see hatched areas) are provided in positions corresponding to interval B in the arrangement direction so as to overlap at least a portion of adjacent resistance heating elements 31, and in this embodiment in particular, are provided over the entire area of ​​interval B. However, while FIG. 35 and FIG. 39 described below show the case where first high thermal conductivity members 28 are provided only in areas corresponding to heat generating portions 35 in the arrangement direction, this is not limited to this, as mentioned above.

[0132] In this embodiment, in addition to the first high thermal conductivity members 28, second high thermal conductivity members 36 are provided at positions corresponding to the interval B in the arrangement direction, overlapping at least a portion of adjacent resistance heating elements 31. This particularly improves the heat transfer efficiency in the arrangement direction at the interval B, thereby further suppressing temperature unevenness in the arrangement direction of the heaters 22. Most preferably, as shown in FIG. 36 , the first high thermal conductivity members 28 and the second high thermal conductivity members 36 are provided only over the entire area of ​​the position corresponding to the interval B. This particularly improves the heat transfer efficiency in the position corresponding to the interval B compared to other areas. For convenience, FIG. 36 illustrates the resistance heating elements 31, the first high thermal conductivity members 28, and the second high thermal conductivity members 36 offset from one another in the vertical direction, but they are positioned at approximately the same position in the cross-arrangement direction. However, this is not a limitation, and the first high thermal conductivity members 28 and the second high thermal conductivity members 36 may be provided only over a portion of the resistance heating elements 31 in the cross-arrangement direction.

[0133] In one embodiment of the present invention different from the above, first high thermal conductivity member 28 and second high thermal conductivity member 36 are formed from the graphene sheet. This allows first high thermal conductivity member 28 and second high thermal conductivity member 36 to be formed with high thermal conductivity in a predetermined direction along the graphene surface, that is, in the arrangement direction rather than the thickness direction. This makes it possible to effectively suppress temperature unevenness in the arrangement direction of heater 22 and fixing belt 20.

[0134] Graphene is a flaky powder. As shown in Figure 37, graphene is made of a planar hexagonal lattice structure of carbon atoms. A graphene sheet is a sheet of graphene, and is usually a single layer. The single layer of carbon may contain impurities. Graphene may also have a fullerene structure. A fullerene structure is generally recognized as a compound in which the same number of carbon atoms form a polycyclic ring in which five-membered and six-membered rings are condensed into a cage shape, and examples thereof include C 60 , C 70 and C 80 Fullerenes or other closed cage structures with three-coordinated carbon atoms.

[0135] Graphene sheets are man-made and can be produced, for example, by chemical vapor deposition (CVD).

[0136] The graphene sheet may be a commercially available product. The size and thickness of the graphene sheet, or the number of layers of the graphite sheet (described later), may be measured using, for example, a transmission electron microscope (TEM).

[0137] Furthermore, graphite, which is a multilayered graphene, has a large thermal conductivity anisotropy. As shown in FIG. 38, graphite has layers in which the layer planes of condensed six-membered rings of carbon atoms extend in a planar fashion, forming a crystalline structure in which these layers are stacked multiple times. In this crystalline structure, adjacent carbon atoms within a layer form covalent bonds, while carbon atoms between layers form van der Waals bonds. Covalent bonds have a stronger bonding strength than van der Waals bonds, resulting in a large anisotropy between intralayer and interlayer bonds. In other words, by constructing the first high thermal conductivity member 28 or the second high thermal conductivity member 36 from graphite, the heat transfer efficiency in the arrangement direction of the first high thermal conductivity member 28 or the second high thermal conductivity member 36 is greater than in the thickness direction (i.e., the stacking direction of the members), thereby suppressing heat transfer to the heater holder 23. This effectively suppresses temperature unevenness in the arrangement direction of the heater 22 and minimizes heat leakage toward the heater holder 23. Furthermore, by making the first high thermal conductivity member 28 or the second high thermal conductivity member 36 out of graphite, the first high thermal conductivity member 28 or the second high thermal conductivity member 36 can have excellent heat resistance, preventing oxidation up to approximately 700 degrees.

[0138] The physical properties and dimensions of the graphite sheet can be changed as appropriate depending on the functions required of first high thermal conductivity member 28 or second high thermal conductivity member 36. For example, the anisotropy of thermal conduction can be increased by using high-purity graphite or single-crystal graphite, or by increasing the thickness of the graphite sheet. Furthermore, in order to increase the speed of fixing device 9, a thin graphite sheet may be used to reduce the heat capacity of fixing device 9. Furthermore, if the width of fixing nip N or heater 22 is large, the width of first high thermal conductivity member 28 or second high thermal conductivity member 36 in the arrangement direction may be increased accordingly.

[0139] From the viewpoint of increasing the mechanical strength, the number of layers of the graphite sheet is preferably at least 11. The graphite sheet may partially include a single layer portion and a multi-layer portion.

[0140] The second high thermal conductivity members 36 may be arranged in positions corresponding to intervals B (and further to regions C) in the arrangement direction so as to overlap at least a portion of adjacent resistance heating elements 31, and are not limited to the arrangement shown in Fig. 35. For example, as shown in Fig. 39, second high thermal conductivity members 36A are arranged to protrude beyond base material 30 on both sides in the cross-array direction. Second high thermal conductivity members 36B are arranged in an area in the cross-array direction where resistance heating elements 31 are arranged. Second high thermal conductivity members 36C are arranged in a portion of intervals B.

[0141] As shown in FIG. 40 , in this embodiment, a gap is provided between the first high thermal conductivity member 28 and the heater holder 23 in the thickness direction (left-right direction in FIG. 40 ). Specifically, a recess 23b (see FIG. 34 ) for accommodating the heater 22, first high thermal conductivity member 28, and second high thermal conductivity member 36 of the heater holder 23 is provided with a relief portion 23c as a heat insulating layer that makes the depth of the recess 23b deeper than the remaining portion that accommodates the first high thermal conductivity member 28. This partial region is part or all of the area other than the portion where the second high thermal conductivity member 36 is provided in the arrangement direction, and is a partial region in the cross-arrangement direction. This minimizes the contact area between the heater holder 23 and the first high thermal conductivity member 28. This suppresses heat transfer from the first high thermal conductivity member 28 to the heater holder 23, allowing the heater 22 to efficiently heat the fixing belt 20. In addition, in the cross section in the arrangement direction where second high thermal conductivity members 36 are provided, second high thermal conductivity members 36 abut against heater holder 23 as in FIG. 33 of the above-described embodiment.

[0142] 40, which is the crossing direction of the arrangement, the relief portion 23c is provided over the entire area where the resistance heating element 31 is provided. This particularly suppresses heat transfer from the first high thermal conductivity member 28 to the heater holder 23, allowing the heater 22 to efficiently heat the fixing belt 20. Note that, in addition to a configuration in which a space is provided as the heat insulating layer, such as the relief portion 23c, a configuration in which a heat insulating member having a lower thermal conductivity than the heater holder 23 is provided may also be used.

[0143] Furthermore, in the above description, second high thermal conductivity member 36 is provided as a member different from first high thermal conductivity member 28, but this is not limiting. For example, the portion of first high thermal conductivity member 28 corresponding to interval B may be made thicker than the other portions.

[0144] In the embodiments shown in Figures 33 and 40, the aforementioned limiting portion on the contact portion of the conductive member limits the area of ​​contact between the contact portion and the inner surface of the rotating member. This prevents the conductive member from scraping away the lubricant. Furthermore, by arranging the conductive member 40 facing the first opposing surface 24d of the stay 24 or the second opposing surface 26a of the guide portion 26, the contact state of the conductive member 40 with the inner surface of the fixing belt 20 can be stabilized, as in the previous embodiments. These effects can be achieved without fixing the conductive member 40 to a specific component within the fixing device with a fixing member such as a screw. Therefore, no space is required for fixing members such as screws, allowing the fixing device to be made smaller. Furthermore, the thermal capacity of the fixing device can be reduced, resulting in energy savings.

[0145] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0146] Furthermore, in addition to the fixing device described above, the present invention can also be applied to fixing devices such as those shown in Figures 41 to 43. The configuration of each fixing device shown in Figures 41 to 43 will be briefly described below.

[0147] First, in the fixing device 9 shown in FIG. 41, a pressure roller 84 is disposed on the opposite side of the fixing belt 20 from the pressure roller 21 side. The pressure roller 84 is an opposing rotating member that rotates opposite the fixing belt 20, which is a rotating member. This pressure roller 84 and heater 22 are configured to sandwich and heat the fixing belt 20. Meanwhile, on the pressure roller 21 side, a nip forming member 85 is disposed on the inner periphery of the fixing belt 20. The nip forming member 85 is supported by the stay 24. The nip forming member 85 and the pressure roller 21 sandwich the fixing belt 20 to form a fixing nip N.

[0148] Guide ribs 260 are provided on the upstream and downstream sides of the nip forming member 85. The conductive member 40 is provided between the upstream guide rib 260 and the stay 24. More specifically, the facing portion 40c of the conductive member 40 is provided to face a first facing surface 260d of the upstream guide rib 260, which is the first facing member in this embodiment, and a second facing surface 24f of the stay 24, which is the second facing member. The facing portion 40c is provided along the first facing surface 260d and the second facing surface 24f. One end 40a of the conductive member 40 contacts the inner surface of the fixing belt 20, which is a rotating member.

[0149] 42, the above-mentioned pressure roller 84 is omitted, and in order to ensure the circumferential contact length between the fixing belt 20 and the heater 22, the heater 22 is formed in an arc shape to match the curvature of the fixing belt 20. The rest of the configuration is the same as that of the fixing device 9 shown in FIG.

[0150] Finally, the fixing device 9 shown in FIG. 43 will be described. The fixing device 9 includes a heating assembly 92, a fixing roller 93 as a fixing member, and a pressure assembly 94 as an opposing pressure member. The heating assembly 92 includes the heater 22, the first high thermal conductivity member 28, the heater holder 23, the stay 24, and the heating belt 120 as a rotating member, as described in the previous embodiment. The fixing roller 93 is an opposing rotating member that rotates opposite the heating belt 120 as a rotating member. The fixing roller 93 includes a solid iron core 93a, an elastic layer 93b formed on the surface of the core 93a, and a release layer 93c formed on the outer surface of the elastic layer 93b. A pressure assembly 94 is provided on the side of the fixing roller 93 opposite the heating assembly 92. The pressure assembly 94 includes a nip forming member 95 and a stay 96, and a pressure belt 97 is rotatably disposed so as to enclose the nip forming member 95 and the stay 96. Then, the paper P is passed through the fixing nip N2 between the pressure belt 97 and the fixing roller 93, and the image is fixed by applying heat and pressure. Arrow J in Figure 43 indicates the rotation direction of the pressure belt.

[0151] Guide ribs 261 are provided on the upstream and downstream sides of nip forming member 95. A plurality of guide ribs 261 are provided in the arrangement direction and are formed in a generally fan shape. Each guide rib 261 has a belt-facing surface 261a that is arc-shaped or convexly curved and extends in the belt circumferential direction so as to face the inner circumferential surface of pressure belt 97.

[0152] The conductive member 40 is provided between the stay 96 and the downstream guide rib 261. More specifically, the facing portion 40c of the conductive member 40 is provided to face the first facing surface 96a of the stay 96, which is the first facing member in this embodiment, and the second facing surface 261b of the downstream guide rib 261, which is the second facing member. The facing portion 40c of the conductive member 40 is provided along the first facing surface 96a and the second facing surface 261b. One end 40a of the conductive member 40 contacts the inner surface of the pressure belt 97, which serves as a rotating member. Note that if the surface layer of the fixing roller 93 and the heating belt 120 are made of a conductive material, the conductive member 40 may be disposed so as to face the first facing surface of the stay 24 and the second facing surface of the upstream guide rib 260, as in the embodiment of FIG. 11 . In this case, one end of the conductive member 40 contacts the inner surface of the heating belt 120, which serves as a rotating member.

[0153] 41 to 43, the contact area of ​​the conductive member can be limited by providing the limiting portion as described above to the contact area of ​​the conductive member, thereby preventing the conductive member from scraping away the lubricant.

[0154] By arranging the conductive member 40 as in the fixing device shown in FIGS. 41 to 43, it is possible to ensure stable contact between the conductive member 40 and the inner surface of the fixing belt 20 (or the inner surface of the pressure belt 97). This allows for proper static elimination of the fixing belt 20 or the pressure belt 97. Furthermore, these effects can be achieved without fixing the conductive member 40 to a predetermined member within the fixing device with a fixing member such as a screw. This eliminates the need for space for fixing members such as screws, allowing for a more compact fixing device. Furthermore, the thermal capacity of the fixing device can be reduced, resulting in energy savings.

[0155] Furthermore, the present invention is not limited to the fixing device described in the above embodiment, but can also be applied to a drying device that dries ink applied to paper, and further to heating devices such as a laminator that thermocompresses a film as a covering member onto the surface of a sheet such as paper, and a heat sealer that thermocompresses the seal portion of a packaging material. By applying the present invention to such devices, it is possible to prevent the lubricant from being scraped off by the conductive member.

[0156] The image forming apparatus according to the present invention is not limited to the color image forming apparatus shown in FIG. 1, but may also be a monochrome image forming apparatus, a copying machine, a printer, a facsimile, or a combination machine of these.

[0157] 44, for example, image forming apparatus 100 of this embodiment includes image forming means 50 including a photosensitive drum and the like, a paper transport section including a pair of timing rollers 15 and the like, paper feeder 7, fixing device 9, paper discharge device 10, and reading section 51. Paper feeder 7 includes multiple paper feed trays, each of which stores paper of a different size.

[0158] The reading unit 51 reads an image of the document Q. The reading unit 51 generates image data from the read image. The paper feeder 7 stores a plurality of sheets of paper P and sends the sheets of paper P to a conveyance path. The timing rollers 15 convey the sheets of paper P on the conveyance path to the image forming means 50.

[0159] The image forming means 50 forms a toner image on the paper P. Specifically, the image forming means 50 includes a photosensitive drum, a charging roller, an exposure device, a developing device, a replenishment device, a transfer roller, a cleaning device, and a discharging device. The toner image represents, for example, an image of the original Q. The fixing device 9 applies heat and pressure to the toner image to fix the toner image to the paper P. The paper P with the fixed toner image is transported to the paper discharge device 10 by a transport roller or the like. The paper discharge device 10 discharges the paper P outside the image forming apparatus 100.

[0160] Next, the fixing device 9 of this embodiment will be described. Descriptions of the configurations common to the fixing devices of the above-described embodiments will be omitted as appropriate.

[0161] As shown in FIG. 45, the fixing device 9 includes a fixing belt 20, a pressure roller 21, a heater 22, a heater holder 23, a stay 24, a thermistor 25, a first high thermal conductivity member 28, a conductive member 40, and the like.

[0162] A fixing nip N is formed between the fixing belt 20 and the pressure roller 21. The nip width of the fixing nip N is 10 mm, and the linear speed of the fixing device 9 is 240 mm / s.

[0163] The fixing belt 20 has a polyimide base and a release layer, but does not have an elastic layer. The release layer is made of a heat-resistant film material such as fluororesin. The outer diameter of the fixing belt 20 is approximately 24 mm.

[0164] The pressure roller 21 includes a core metal 21a, an elastic layer 21b, and a release layer 21c. The pressure roller 21 has an outer diameter of 24 to 30 mm, and the elastic layer 21b has a thickness of 3 to 4 mm.

[0165] The heater 22 includes a base material, a heat insulating layer, a conductor layer including a resistance heating element, and an insulating layer, and is formed to a total thickness of 1 mm. The width Y of the heater 22 in the array crossing direction is 13 mm.

[0166] The conductive member 40 is provided between the stay 24 and the downstream guide rib 260. More specifically, the facing portion 40c of the conductive member 40 is provided to face the first facing surface 24d of the stay 24 as a first facing member and the second facing surface 260c of the downstream guide rib 260 as a second facing member. One end 40a of the conductive member 40 contacts the inner surface of the fixing belt 20 as a rotating member.

[0167] As shown in FIG. 46, the conductor layer of the heater 22 includes a plurality of resistance heating elements 31, power supply lines 33, and electrode portions 34A-34C. In this embodiment, as shown in the enlarged view of FIG. 46, the resistance heating elements 31 are divided in the arrangement direction to form intervals B as divided regions (although FIG. 46 only illustrates the intervals B within the enlarged view, in reality, intervals B are provided between all of the resistance heating elements 31). The resistance heating elements 31 form three heat generating portions 35A-35C. By applying electricity to the electrode portions 34A and 34B, the heat generating portions 35A and 35C generate heat. By applying electricity to the electrode portions 34A and 34C, the heat generating portion 35B generates heat. For example, when performing a fixing operation on small-sized paper, the heat generating portion 35B is made to generate heat, and when performing a fixing operation on large-sized paper, all of the heat generating portions are made to generate heat.

[0168] As shown in Figure 47, the heater holder 23 holds the heater 22 and the first high thermal conductivity member 28 in its recess 23d. The recess 23d is provided on the heater 22 side of the heater holder 23. The recess 23d is composed of a surface 23d1 that is approximately parallel to the base material 30 and is recessed toward the stay 24 side more than the other surfaces of the heater 22, wall portions 23d2 provided on the inside of the heater holder 23 on both sides in the arrangement direction of the heater holder 23 (or on one side), and wall portions 23d3 provided on the inside of the heater holder 23 on both sides in the intersecting direction of the arrangement. The heater holder 23 has a guide portion 26. The heater holder 23 is made of LCP (liquid crystal polymer).

[0169] As shown in FIG. 48, the connector 60 includes a housing made of resin (for example, LCP), and a plurality of contact terminals provided inside the housing.

[0170] The connector 60 is attached so as to sandwich the heater 22 and heater holder 23 together from the front and back sides. In this state, each contact terminal comes into contact (pressure-welded) with each electrode portion of the heater 22, electrically connecting the heat generating portion 35 to a power supply provided in the image forming apparatus via the connector 60. This enables power to be supplied from the power supply to the heat generating portion 35. Note that, to ensure connection with the connector 60, at least a portion of each electrode portion 34 is not covered with an insulating layer and is exposed.

[0171] The flanges 53 are provided on both sides of the fixing belt 20 in the arrangement direction, and hold both ends of the fixing belt 20 from the inside of the belt. The flanges 53 are fixed to the housing of the fixing device 9. The flanges 53 are inserted into both ends of the stays 24 (see the arrow directions from the flanges 53 in Figure 48).

[0172] The direction in which the connector 60 is attached to the heater 22 and heater holder 23 is the direction that intersects the heater arrangement (see the direction of the arrow from the connector 60 in Figure 48). When the connector 60 is attached to the heater holder 23, a convex portion on one of the connector 60 and the heater holder 23 may engage with a concave portion on the other, and the convex portion may move relatively within the concave portion. The connector 60 is attached to the heater 22 and heater holder 23 on one side in the arrangement direction, opposite the side on which the drive motor of the pressure roller 21 is provided.

[0173] 49, thermistors 25 are provided on the center side and end side of the arrangement direction of the fixing belt 20, facing the inner circumferential surface of the fixing belt 20. The heater 22 is controlled based on the temperatures detected by the thermistors 25 on the center side and end side of the arrangement direction of the fixing belt 20.

[0174] Thermostats 27 are provided facing the inner circumferential surface of the fixing belt 20, at the center and end sides in the arrangement direction of the fixing belt 20. When the temperature of the fixing belt 20 detected by the thermostat 27 exceeds a predetermined threshold, the supply of power to the heater 22 is stopped.

[0175] Flanges 53 are provided on both ends of the fixing belt 20 in the arrangement direction to hold the respective ends of the fixing belt 20. The flanges 53 are made of LCP (liquid crystal polymer).

[0176] 50, a slide groove 53a is provided in the flange 53. The slide groove 53a extends in the direction in which the fixing belt 20 approaches and separates from the pressure roller 21. An engagement portion of the housing of the fixing device 9 engages with the slide groove 53a. The engagement portion moves relatively within the slide groove 53a, allowing the fixing belt 20 to move in the direction in which the fixing belt 20 approaches and separates from the pressure roller 21.

[0177] In the fixing device 9, the aforementioned limiting portion is provided at the contact portion of the conductive member, thereby limiting the area where the contact portion comes into contact with the inner surface of the rotating member. This prevents the conductive member from scraping away the lubricant. Furthermore, the arrangement of the fixing member or the conductive member 40 allows the conductive member 40 to come into stable contact with the inner surface of the fixing belt 20. As described above, the fixing device can be made smaller.

[0178] Recording media include paper P (plain paper), as well as cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, plastic film, prepreg, copper foil, etc. [Explanation of symbols]

[0179] 1. Image forming device 9 Fixing device (heating device) 20 Fixing belt (rotating member or fixing member) 21 Pressure roller (opposing rotating member or pressure member) 22 Heater (heating element) 23 Heater holder (holding member) 31 Resistance heating element 40 Conductive material 40a One end of the conductive member (contact portion) 40b Other end of conductive member 40g bent part 405 Slit 42 Screws (fixing members) D Center position of the fixing belt in the longitudinal direction N Fixing nip (nip part) P Paper (recording medium) X Longitudinal direction of the fixing belt [Prior art documents] [Patent documents]

[0180] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-166299

Claims

1. A rotating member; a pressure member that applies pressure to the rotary member and forms a fixing nip between the rotary member and the pressure member; a conductive member that is grounded and in contact with the inner surface of the rotating member; a heating element that contacts the inside of the rotating member and heats the rotating member, the conductive member has a limiting portion at a contact portion provided at an end portion on the rotating member side, the limiting portion limiting a contact area with the rotating member; The fixing device is characterized in that the limiting portion has a tapered shape in which the width thereof narrows toward the tip of the conductive member on the side of the rotating member.

2. A rotating member; a pressure member that applies pressure to the rotary member and forms a fixing nip between the rotary member and the pressure member; a conductive member that is grounded and in contact with the inner surface of the rotating member; a heating element that contacts the inside of the rotating member and heats the rotating member, the conductive member has a limiting portion at a contact portion provided at an end portion on the rotating member side, the limiting portion limiting a contact area with the rotating member; The fixing device according to claim 1, wherein the limiting portion is provided with a slit, and the slit divides the contact portion into a plurality of portions that come into contact with the rotating member.

3. A rotating member; a pressure member that applies pressure to the rotary member and forms a fixing nip between the rotary member and the pressure member; a conductive member that is grounded and in contact with the inner surface of the rotating member; a heating element that contacts the inside of the rotating member and heats the rotating member, the conductive member has a limiting portion at a contact portion provided at an end portion on the rotating member side, the limiting portion limiting a contact area with the rotating member; A plurality of the conductive members are provided, a fixing device, wherein the contact portions of the plurality of conductive members that come into contact with the rotating member are provided at positions symmetrical on one side and the other side with respect to a central position in the longitudinal direction of the rotating member;

4. 4. The fixing device according to claim 3, wherein the limiting portion has a tapered shape whose width narrows toward the tip of the conductive member on the side of the rotating member.

5. 5. The fixing device according to claim 1, wherein the contact portion is divided into a plurality of portions that come into contact with the rotating member.

6. 6. The fixing device according to claim 5, wherein the limiting portion has a slit, and the slit divides the contact portion into a plurality of contact points with the rotating member.

7. The fixing device according to claim 2 , wherein the limiting portion has a plurality of protrusions at the tip of the contact portion and a recess that is recessed from the protrusions toward the opposite side of the contact portion of the conductive member from the side of the contact portion.

8. The fixing device according to claim 1 , wherein the contact portion has a width smaller than that of the other portion of the conductive member.

9. The fixing device according to claim 1 , wherein the conductive member has a bent portion bent by plastic deformation on the contact portion side.

10. The fixing device according to claim 1 , wherein a contact portion of the conductive member that comes into contact with the rotating member is provided at a center position in the longitudinal direction of the rotating member.

11. 11. The fixing device according to claim 1, wherein the rotating member does not have a conductive elastic layer.

12. 12. The fixing device according to claim 1, wherein the heater has a resistance heating element divided into a plurality of parts.

13. An image forming apparatus comprising the fixing device according to claim 1 .

Images