Fixing system and image forming apparatus

Abstract

Compared to when the processor only runs in fuser mode, this suppresses fuser failures. [Solution] The fixing system comprises a rotating body, an endless fixing member having a clamping region formed between the rotating body and the medium when pressurized by the rotating body, a heating member having a contact region that contacts the inner circumference of the fixing member in the clamping region via a lubricant containing a thickener and generating heat in the contact region, and a processor, the processor performing a fixing mode in which the fixing member heated by the heating member clamps the medium between the rotating body and the medium in the clamping region formed in the pressurized state and rotates in one direction to fix the image on the medium, and a rotation mode in which the fixing member rotates in the one direction in a relaxed state in which the pressurized state is relieved.

Description

Technical Field

[0001] The present disclosure relates to a fixing system and an image forming apparatus.

Background Art

[0002] Patent Document 1 discloses an image heating apparatus having a rotatable flexible member, a radiation heating source, a support member, a pressure member, and a pressure applying means. The radiation heating source is disposed at a position spaced from the flexible member inside the flexible member. The support member supports the inner surface side of the flexible member and forms a sliding surface coated with a lubricant on the inner surface side. The pressure member forms a nip portion with the support member through the flexible member. The pressure applying means applies a pressure between the pressure member and the support member. The image heating apparatus heats while passing a recording material through the nip portion. Further, the image heating apparatus has a pressure relaxation means and a lubricant displacement means. The pressure relaxation means relaxes the pressure applied by the pressure applying means. The lubricant displacement means displaces at least a part of the lubricant moved downstream by paper passage together with the flexible member to a position upstream of the sliding surface during paper passage and not irradiated with direct light from the radiation heating source.

[0003] Patent Document 2 discloses a heating apparatus having a film, a support member, and a pressure member. The support member has a sliding surface on which the film slides and supports the film. The pressure member sandwiches the film therebetween and forms a pressure contact nip portion with the sliding surface. The heating apparatus heats while sandwiching and conveying a material to be heated between the film and the pressure member while sliding the film on the sliding surface. Further, the heating apparatus interposes a lubricant containing a fluororesin powder having an average secondary aggregation particle diameter of 10 to 30 μm between the sliding surface and the film.

[0004] Patent Document 3 discloses an image heating device comprising a belt member, a drive member, a sliding member, and a means for heating the belt member. The belt member has a lubricant applied to its inner surface. The drive member contacts the outer surface of the belt member and rotates the belt member. The sliding member slides against the inner surface of the belt member, sandwiching the belt member between itself and the drive member. The image heating device further comprises a pressurizing mechanism and a control means. The pressurizing mechanism can change the pressure applied to the belt member by the drive member and the sliding member. The control means can execute a lubricant transfer mode in which the belt member is rotated by the drive member while the pressurizing force applied by the pressurizing mechanism is lower than that used during image heating. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2013-130793 [Patent Document 2] Japanese Patent Publication No. 2005-317519 [Patent Document 3] Japanese Patent Publication No. 2011-33654 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] A possible fixing system includes a rotating body, an endless fixing member, a heating member, and a processor. In a pressurized state where the endless fixing member is pressurized by the rotating body, a clamping region is formed where the medium is sandwiched between the rotating body and the fixing member. The heating member has a contact region in the clamping region that contacts the inner circumference of the fixing member via a lubricant containing a thickener, and generates heat in the contact region.

[0007] Furthermore, in this system, it is conceivable that the processor may only perform a fixing mode in which a fixing member heated by a heat-generating element clamps the medium between the medium and a rotating body in a clamping region formed under pressure, thereby fixing the image on the medium. In this case, for example, if the particle size of the thickener contained in the lubricant is large, the lubricant that has leaked out from between the heat-generating element and the fixing member cannot re-enter the space, and the amount of lubricant between the heat-generating element and the fixing member decreases in the clamping region. As a result, fixing failure may occur.

[0008] This disclosure aims to suppress fixing defects compared to a case where the processor only performs a fixing mode in which a fixing member heated by a heat-generating member clamps the medium between a rotating body and a fixing member in a clamping region formed under pressure, and rotates in one direction to fix the image on the medium. [Means for solving the problem]

[0009] The first embodiment comprises a rotating body, an endless fixing member having a clamping region formed between it and the rotating body when pressurized by the rotating body, a heating member having a contact region that contacts the inner circumference of the fixing member in the clamping region via a lubricant containing a thickener and generating heat in the contact region, and a processor, wherein the processor performs a fixing mode in which the fixing member heated by the heating member clamps the medium between it and the rotating body in the clamping region formed in the pressurized state and rotates in one direction to fix an image on the medium, and a rotation mode in which the fixing member rotates in the one direction in a relaxed state in which the pressurized state is relieved.

[0010] In the second embodiment, in the first embodiment, the processor brings the rotating body and the fixing member into contact in the relaxation state in the rotation mode.

[0011] In the third embodiment, in the second embodiment, the processor rotates the fixing member in accordance with the rotation of the rotating body in the relaxation state in the rotation mode.

[0012] In the fourth embodiment, in the first embodiment, the processor makes the dimension between the unidirectional upstream portion of the contact area of ​​the heating element and the fixing element larger than the dimension in the pressurized state in the relaxation state in the rotation mode.

[0013] In the fifth embodiment, in the fourth embodiment, the processor rotates the fixing member in the rotation mode, thereby guiding the lubricant present upstream of the upstream portion in that direction to the space between the upstream portion and the fixing member.

[0014] In the sixth embodiment, in the first embodiment, the processor makes the distance between the upstream portion in one direction of the contact area of ​​the heating element and the fixing element larger than the distance between the central portion in one direction of the contact area and the fixing element in the relaxation state of the rotation mode.

[0015] In the seventh embodiment, as in the sixth embodiment, the processor rotates the fixing member in the rotation mode, thereby guiding the lubricant present upstream of the upstream portion in that direction to the space between the upstream portion and the fixing member.

[0016] The eighth embodiment comprises an image forming unit that forms an image on a medium, and a fixing system according to any one of the first to seventh embodiments for fixing the image formed on the medium. [Effects of the Invention]

[0017] According to the configuration of the first embodiment, compared to the case in which the processor only performs a fixing mode in which a fixing member heated by a heat-generating member clamps the medium between the rotating body and the medium in a clamping region formed under pressure and rotates in one direction to fix the image on the medium, fixing defects are suppressed.

[0018] According to the configuration of the second embodiment, the driving force of the rotating body can be directly transmitted to the fixing member.

[0019] According to the configuration of the third aspect, a driving force for driving the fixing member becomes unnecessary.

[0020] According to the configuration of the fourth aspect, when the processor makes the dimension between the upstream portion in one direction in the contact region and the fixing member in the relaxation state in the rotation mode the same as the dimension in the pressurized state, fixing failure is suppressed as compared with the case where they are not the same.

[0021] According to the configuration of the fifth aspect, when the processor retains the lubricant existing upstream in one direction with respect to the upstream portion in the rotation mode, fixing failure is suppressed as compared with the case where the lubricant is not retained upstream.

[0022] According to the configuration of the sixth aspect, when the processor makes the dimension between the upstream portion in one direction in the contact region and the fixing member in the relaxation state in the rotation mode the same as the dimension in the central portion, fixing failure is suppressed as compared with the case where they are not the same.

[0023] According to the configuration of the seventh aspect, when the processor retains the lubricant existing upstream in one direction with respect to the upstream portion in the rotation mode, fixing failure is suppressed as compared with the case where the lubricant is not retained upstream.

[0024] According to the configuration of the eighth aspect, image failure is suppressed as compared with the case where the processor only executes the fixing mode in which the fixing member heated by the heat generating member sandwiches the medium with the rotating body in the sandwiching region formed in the pressurized state and rotates in one direction to fix the image of the medium.

Brief Description of Drawings

[0025] [Figure 1] It is a schematic diagram showing an image forming apparatus according to the present embodiment. [Figure 2] It is a block diagram showing the hardware configuration of a controller according to the present embodiment. [Figure 3] It is a front cross-sectional view showing a separated state in which a pressure roll is separated from a fixing belt in a fixing system according to the present embodiment. [Figure 4]This is a cross-sectional view showing the pressurized state in which the pressure roll is pressed against the fixing belt in the fixing system according to this embodiment. [Figure 5] In the fixing system according to this embodiment, Figure 4 is a cross-sectional view showing the relaxed state of the pressure roll that relieves the pressure state shown. [Figure 6] This schematic diagram shows a portion of the heater, fixing belt, and pressure roll, as well as a grease thickener, in the pressurized state of the pressure roll according to this embodiment. [Figure 7] This schematic diagram schematically shows a portion of the heater, fixing belt, and pressure roll, as well as a grease thickener, in the relaxed state of the pressure roll according to this embodiment. [Figure 8] This flowchart shows the modes that the controller according to this embodiment can execute. [Figure 9] This is a flowchart showing the case when the controller according to this embodiment executes the grease induction mode. [Modes for carrying out the invention]

[0026] An example of an embodiment relating to this disclosure will be described below with reference to the drawings.

[0027] In each figure, arrow H indicates the vertical direction of the image forming apparatus, arrow W indicates the width direction of the image forming apparatus, and arrow D indicates the depth direction of the image forming apparatus. These vertical, width, and depth directions intersect each other (specifically, are orthogonal directions). The +R direction is the direction of counterclockwise rotation with the depth direction as the axis. The -S direction is the direction of clockwise rotation with the depth direction as the axis. These directions are defined for the sake of explanation and do not mean that the configuration of the image forming apparatus is limited to these directions. In some cases, the term "image forming apparatus" is omitted in each direction of the image forming apparatus. The symbol with a "·" inside a "○" in the figures means an arrow pointing from the back of the page to the front.

[0028] In this disclosure, numerical ranges indicated using "~" include the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages within this disclosure, the upper or lower limit of one numerical range may be replaced by the upper or lower limit of another numerical range described in stages.

[0029] <Image forming apparatus 10> The image forming apparatus 10 forms an image on a sheet material P, such as paper. The sheet material P is an example of a medium in this disclosure. In the image forming apparatus 10, as shown in Figure 1, the various parts are arranged inside the apparatus body 10a. The image forming apparatus 10 includes a storage unit 12, a main operation unit 14, a transport unit 18, and a controller 70. The image forming apparatus 10 further includes a display unit 40 as an interface for the user to exchange information with the image forming apparatus 10.

[0030] <Storage section 12> The storage section 12 houses the sheet members P. The storage section 12 has a first storage section 22, a second storage section 24, a third storage section 26, and a fourth storage section 28. For example, sheet members P of different sizes are appropriately stored in the first storage section 22, the second storage section 24, the third storage section 26, and the fourth storage section 28. The first storage section 22, the second storage section 24, the third storage section 26, and the fourth storage section 28 are also equipped with a feed roll 32 and a double-feed prevention roll 34, respectively. The feed roll 32 feeds out the stored sheet members P one by one based on instructions from the controller 70. The double-feed prevention roll 34 transports the sheet members P fed out by the feed roll 32 one by one to the transport path 30 in the image forming apparatus 10.

[0031] Although the storage unit 12 had multiple storage units, the storage unit of this disclosure is not limited to this. The storage unit of this disclosure may consist of a single storage unit. Furthermore, when the storage unit of this disclosure has multiple storage units, the number is not limited to four.

[0032] <Main operating section 14> The main operating unit 14 outputs image data sent from a user terminal (not shown) or a document reading unit 16 to a sheet member P transported from a storage unit 12. The main operating unit 14 includes an image forming unit 60 and a fixing device 100. The image forming unit 60 is an example of an image forming unit in this disclosure.

[0033] The image forming unit 60 forms a toner image. The toner image is an example of an image in this disclosure. The image forming unit 60 has image forming units 64Y, 64M, 64C, and 64K that form toner images of yellow (Y), magenta (M), cyan (C), and black (K). In the following description, unless otherwise specified, the Y, M, C, or K at the end of the reference numerals may be omitted.

[0034] The image forming unit 64 comprises a photoreceptor drum 62, a charger 42, a developer 44, a cleaning member 46, and an exposure device 66 (66Y, 66M, 66C, and 66K). The charger 42 charges the rotating photoreceptor drum 62, and the exposure device 66 irradiates the charged photoreceptor drum 62 with exposure light to form an electrostatic latent image. Furthermore, the developer 44 develops the electrostatic latent image and visualizes it as a toner image. In other words, the image forming apparatus 10 of this embodiment is an electrophotographic apparatus.

[0035] The image forming unit 60 further includes a transfer unit 68. The transfer unit 68 transfers the toner image to the sheet member P. The transfer unit 68 is positioned below the image forming units 64Y, 64M, 64C, and 64K. The transfer unit 68 comprises a transfer belt 48, a primary transfer roll 50, a secondary transfer roll 52, an auxiliary roll 54, and a roll 56.

[0036] The transfer belt 48 is formed in an endless manner and has a triangular shape with its vertex pointing downwards when viewed from the front side in the depth direction.

[0037] The primary transfer rolls 50 (50K, 50C, 50M, and 50Y) are positioned in conjunction with the photoconductor drum 62, and sandwich the transfer belt 48 between them, transferring the toner image from the photoconductor drum 62 to the transfer belt 48.

[0038] The secondary transfer roll 52 is positioned below the primary transfer roll 50 and transfers the toner image on the transfer belt 48 to the sheet material P at the transfer position T.

[0039] The auxiliary roll 54 is positioned inside the transfer belt 48 and on the opposite side of the secondary transfer roll 52, with the transfer belt 48 in between.

[0040] Multiple rolls 56 are arranged inside the transfer belt 48, and the transfer belt 48 is wrapped around them. At least one of the rolls 56 functions as a drive roll that causes the transfer belt 48 to rotate in the direction of arrow C in the figure.

[0041] The fixing device 100 is positioned downstream of the transfer position T and fixes the toner image transferred onto the sheet member P to the sheet member P. Details of the fixing device 100 will be described later.

[0042] <Conveying section 18> The conveying unit 18 receives sheet members P that are conveyed from the double-feed prevention roll 34 or inserted from outside the main body of the device 10a and conveys them one by one. The conveying unit 18 has a conveying path 30, a conveying roll 36, and a conveying device 38.

[0043] The transport path 30 is the path that determines the transport direction of the sheet member P (hereinafter simply referred to as "transport direction CV").

[0044] The upstream portion of the transport path 30 extends from bottom to top on one side in the width direction. A manual feed path 33 is connected to the upper end of the upstream portion of the transport path 30.

[0045] The downstream portion of the transport path 30 extends from one side in the width direction to the other, and is connected to a discharge section 80 that discharges the sheet member P to the outside of the device body 10a. A double-sided transport path 31 is connected to the downstream end of the transport path 30, where the sheet member P is transported and inverted in order to form an image on the back surface of the sheet member P. The double-sided transport path 31 is equipped with a switchback path 31a, and the sheet member P sent out from the switchback path 31a is inverted front and back and sent to the upper end of the upstream portion of the transport path 30 in the transport direction CV.

[0046] Multiple conveyor rolls 36 are arranged along the conveyor path 30. The conveyor rolls 36 are arranged in pairs on the main body 10a of the device so as to sandwich the conveyor path 30.

[0047] The transport device 38 is positioned upstream of the transfer position T in the transport direction CV, and temporarily stops the sheet member P, then sends the sheet member P to the secondary transfer position at a predetermined timing.

[0048] <Controller 70> The controller 70 is a computer that controls each part of the image forming apparatus 10. As shown in Figure 2, the controller 70 has the following components: CPU (Central Processing Unit) 72A, ROM (Read Only Memory) 72B, RAM (Random Access Memory) 72C, storage 72D, input / output unit 74, and network interface (network I / F) 76. Each component is connected to the others so as to be able to communicate with each other via bus 72E.

[0049] The CPU 72A is a central processing unit that executes various programs and controls various components. Specifically, the CPU 72A reads a program from the ROM 72B or storage 72D and executes the program using the RAM 72C as a working area. The CPU 72A is an example of the processor of this disclosure. The CPU 72A controls each of the above components and performs various calculations according to the program recorded in the ROM 72B or storage.

[0050] ROM72B stores various programs and data. RAM72C temporarily stores programs or data as a working area. Storage72D consists of storage devices such as HDD (Hard Disk Drive) and SSD (Solid State Drive) and stores various programs, including the operating system, and various data.

[0051] The input / output unit 74 receives signals between the various components of the image forming apparatus 10 in order to enable the image forming apparatus 10 to perform its functions. For example, the input / output unit 74 receives signals between the storage unit 12, the main operating unit 14, and the transport unit 18.

[0052] Network I / F76 is an interface for communicating with other devices, and standards such as Ethernet®, FDDI, and Wi-Fi® are used.

[0053] <Details of the fixing device 100> The fixing device 100 is a device that fixes a toner image to a sheet member P. As shown in Figures 3, 4, and 5, the fixing device 100 includes a pressure roll 120 and a heating unit 140.

[0054] In the fixing device 100, the toner image is fixed to the sheet member P using the pressure roll 120 and the heating unit 140. Specifically, in the fixing device 100, the toner image transferred to the sheet member P in the image forming unit 60 is fixed to the sheet member P by heating and pressurizing the sheet member P that has been transported from the transfer position T.

[0055] The fuser device 100, together with the controller 70, constitutes the fuser system 90. Alternatively, the fuser system 90 may be understood as consisting of the fuser device 100 and the CPU 72A in the controller 70.

[0056] <Pressure Roll 120> The pressure roll 120 is a roll-shaped member oriented in the depth direction, as shown in Figures 3, 4, and 5. The pressure roll 120 is positioned below the transport path 30. The pressure roll 120 is rotatably supported with respect to the device body 10a and is rotationally driven in the -S direction by a drive unit (not shown). The pressure roll 120 is an example of a rotating body of this disclosure. The pressure roll 120 is also made to be able to move toward and away from the fixing belt 142 by a separation mechanism (not shown). As a result, the pressure roll 120 can change between a separated state shown in Figure 3, where it is separated from the fixing belt 142; a pressed state shown in Figure 4, where it is pressed against the fixing belt 142; and a relaxed state shown in Figure 5, where the pressed state is relaxed.

[0057] The pressure roll 120 has a multilayer structure comprising, for example, a core metal 124, an elastic layer 122, and a release layer 126. The core metal 124 is a thin-walled cylindrical shape made of steel and is supported by the main body 10a of the apparatus. The elastic layer 122 is a layer containing silicone rubber or the like that is coated on the surface of the core metal 124. The release layer 126 is a surface layer that is coated on the surface of the elastic layer 122.

[0058] <Heating section 140> The heating unit 140 is a structure that follows the depth direction, as shown in Figures 3, 4, and 5. The heating unit 140 is positioned above the transport path 30. The heating unit 140 is configured to melt the toner on the sheet member P. The heating unit 140 comprises a fixing belt 142, a heater 144, a pad 146, and a support member 148. The fixing belt 142 is an example of a fixing member of this disclosure. The heater 144 is an example of a heat-generating member of this disclosure.

[0059] The fixing belt 142 is an endless belt with the depth direction as its axial direction. The fixing belt 142 has a thin-walled cylindrical base material made of a synthetic resin such as polyimide resin or polyamide-imide resin, and a release layer containing fluororesin is provided on its outer surface as needed. The fixing belt 142 is rotatably supported with respect to the main body 10a of the apparatus.

[0060] The fixing belt 142 has a fixing nip N. The fixing nip N is formed when the pressure roll 120 is pressed against the fixing belt 142, resulting in the pressurized state shown in Figure 4. The fixing nip N is the region in which the fixing belt 142 sandwiches the sheet member P between itself and the pressure roll 120. The fixing nip N is an example of the sandwiching region of this disclosure.

[0061] The fixing belt 142 can rotate in the +R direction in conjunction with the rotation of the pressure roll 120 while in contact with the pressure roll 120.

[0062] The heater 144 is a heat-generating device. Specifically, the heater 144 is a planar heating element positioned along the depth direction and inside the fixing belt 142. The heater 144 has a contact area 144S that contacts the inner circumference of the fixing belt 142 via grease G at the fixing nip N. The first dimension of the contact area 144S in the +R direction is, for example, larger than the second dimension of the fixing nip N in the +R direction. The first and second dimensions may be the same. The heater 144 generates heat by, for example, having a wiring pattern formed on the contact area 144S and being energized based on instructions from the controller 70.

[0063] Grease G is a lubricant that reduces the sliding resistance between the fixing belt 142 and the heater 144 when sandwiched between them. Grease G has a lower consistency than fluorine grease. For example, the mixed consistency of grease G is 250 or less as specified in JIS K 2220. Furthermore, the viscosity of grease G at 200°C measured with a rheometer is 50 to 1500 Pa·s, preferably 80 to 1000 Pa·s, and more preferably 100 to 500 Pa·s. The weight loss rate of grease G when heated and stored at 230°C for 336 hours is 0 to 20 wt%, preferably 0 to 15 wt%, and more preferably 0 to 10 wt%.

[0064] Grease G is composed of a base oil combined with a thickener. The base oil of Grease G is a silicone oil, preferably dimethyl silicone oil, methylphenyl silicone oil, or diphenyl silicone oil, and may have partially introduced side chains. The weight-average molecular weight Mw of the silicone oil is 10,000 to 100,000, preferably 10,000 to 60,000, and more preferably 15,000 to 40,000.

[0065] Furthermore, in Grease G, one or more inorganic materials such as melamine cyanurate, boron nitride, carbon black, silica, graphite, molybdenum disulfide, zinc stearate, and tungsten disulfide are selected as components of the thickener. The average particle size (D50v) of the thickener is 0.01 to 15 μm, preferably 0.1 to 10 μm, and more preferably 0.1 to 5 μm. The weight ratio of base oil in the components of Grease G is 40 to 95 wt%, preferably 50 to 85 wt%, and more preferably 50 to 75 wt%.

[0066] The viscosity of grease G is measured by the following method: The grease sample is placed between parallel plates with a diameter of 40 mm, and the viscosity is measured using a dynamic viscoelasticity measuring device (rheometer ARES-G2, manufactured by T.A. Instruments Inc.) with a gap of 1 mm and an angular velocity of 0.1 rad / s, while the temperature is raised from 40°C to 200°C at a rate of 6°C / min.

[0067] The weight loss rate of grease G is calculated by taking a 5g sample of grease in an aluminum cup and heating it in an oven at 230°C for 336 hours, then comparing the weight before and after heating.

[0068] The average particle size of the thickener is measured by the following method: A 2g sample of grease is placed on filter paper, and 30g of THF (tetrahydrofuran) is added and filtered by suction to separate the base oil and the thickener. The separated thickener is dispersed in water, and the particle size distribution is measured using a particle size analyzer (LS13320, Beckman Coulter).

[0069] Here, the particle size of the thickener in grease G is larger than that of the thickener in fluorine grease. Furthermore, the particle size GR of the thickener in grease G is larger than the dimension L1 between the contact area 144S at the fixing nip N of the pressure roll 120 in the pressurized state shown in Figure 4 and the fixing belt 142, as shown in Figure 6. This dimension L1 is, for example, 3 μm to 10 μm. On the other hand, the particle size GR of the thickener in grease G is, for example, 20 μm to 50 μm. Therefore, due to the rotation of the fixing belt 142 in the +R direction, the thickener in grease G that flows out from between the contact area 144S of the heater 144 and the fixing belt 142 is unlikely to flow back into that space. The grease G that flows out from that space may form a pool upstream of that space due to the rotation of the fixing belt 142. Figure 6 is a schematic diagram illustrating parts of the heater 144, fixing belt 142, and pressure roll 120, as well as the thickener of the grease G, in the pressurized state of the pressure roll 120.

[0070] As shown in Figures 3 and 4, the pad 146 is a block-shaped member positioned along the depth direction and inside the fixing belt 142. The pad 146 supports the heater 144 from the outside, covering it from the inside of the fixing belt 142. In other words, the pad 146 supports the heater 144 at the upstream side of the downstream end 146A and the downstream side of the upstream end 146B in the +R direction (in other words, the conveying direction CV). The pad 146 is positioned such that the downstream end 146A and the upstream end 146B are in contact with the inner circumferential surface of the fixing belt 142 when the pressure roll 120 is pressurized against the fixing belt 142. The pad 146 is supported by the main body 10a of the device. The pad 146 directs the outer circumferential surface of the fixing belt 142 toward the outer circumferential surface of the pressure roll 120. The pad 146 further has a recess 146C. The recess 146C is a recessed portion formed on the surface opposite to the support surface of the heater 144.

[0071] The support member 148 is positioned along the depth direction and inside the fixing belt 142, and has a frame shape that is an inverted U when viewed from the depth direction. The support member 148 is supported by the main body 10a of the device. The support member 148 supports the pad 146 via the recess 146C. The support member 148 receives the pressing force of the pressure roll 120 via the heater 144 and the pad 146 when the fixing belt 142 is pressed against the pressure roll 120.

[0072] <Mode> The controller 70 performs a fixing mode and a grease induction mode in the fixing device 100. The grease induction mode is an example of a rotation mode in this disclosure.

[0073] <Fixing Mode> The fixing mode is a mode in which the toner image is fixed to the sheet material P. The fixing mode is performed when the image forming apparatus 10 forms an image.

[0074] In fixing mode, the fixing belt 142, heated by the heater 144, rotates the sheet member P in the +R direction by sandwiching it between the fixing nip N and the pressure roll 120, thereby fixing the image on the sheet member P.

[0075] In this embodiment, the fixing mode is specifically performed as follows: The pressure roll 120 is pressed to the state shown in Figure 4 to form a fixing nip N. The heater 144 generates heat in the contact area 144S. The pressure roll 120 is then rotated in the -S direction. As a result, the fixing belt 142 is driven to rotate in the +R direction, sandwiching the sheet member P between the fixing nip N and the pressure roll 120, thereby fixing the image on the sheet member P. Note that the +R direction is just one example of a direction.

[0076] <Grease induction mode> The grease induction mode is a mode in which grease G that has leaked out from between the contact area 144S of the heater 144 and the fixing belt 142 is guided into that space. In the grease induction mode, the fixing belt 142 rotates in the +R direction with the pressure of the pressure roll 120 released.

[0077] Here, as described above, the pressure roll 120 is capable of changing from the separated state shown in Figure 3 and the pressurized state shown in Figure 4 to the relaxed state shown in Figure 5, in addition to the separated state shown in Figure 3 and the pressurized state shown in Figure 4, by a separation mechanism (not shown).

[0078] The relaxed state of the pressure roll 120 is a state in which the pressure applied by the pressure roll 120 to the fixing belt 142 is reduced compared to the pressurized state. The distance LA (see Figure 5) between the axes of the pressure roll 120 and the fixing belt 142 is longer in the relaxed state than in the pressurized state, and shorter than in the separated state. The same relationship applies to the distances between the axis of the pressure roll 120 and the heater 144, pad 146, and support member 148.

[0079] In the relaxed state, the pressure roll 120 is in contact with the fixing belt 142. Therefore, in the relaxed state of the pressure roll 120, the fixing belt 142 is able to rotate in accordance with the rotation of the pressure roll 120. The contact range between the pressure roll 120 and the fixing belt 142 along the +R direction (in other words, the conveying direction) is shorter in the relaxed state than in the pressurized state.

[0080] Furthermore, in the relaxed state of the pressure roll 120, the dimension LB (see Figure 7) between the upstream portion 144X in the +R direction of the contact area 144S of the heater 144 and the fixing belt 142 (hereinafter referred to as gap X) is larger than the dimension LB in the pressurized state.

[0081] Furthermore, in the relaxed state of the pressure roll 120, the dimension LB is larger than the dimension LC (see Figure 7) between the central portion 144Y in the +R direction of the contact area 144S and the fixing belt 142.

[0082] In this way, the CPU 72A enlarges the gap X in the grease induction mode. Then, in the grease induction mode, the CPU 72A rotates the fixing belt 142 in the +R direction to guide the thickener of the grease G into the enlarged gap X.

[0083] Figure 7 is a schematic diagram illustrating parts of the heater 144, fixing belt 142, and pressure roll 120 in the relaxed state of the pressure roll 120, as well as the thickener of the grease G. The specific operation of each part in the grease induction mode will be explained later using a flowchart.

[0084] <Flowchart> <Mode Determination> The mode switching in the controller 70 will be explained with reference to Figure 8. In step S10, the CPU 72A of the controller 70 determines whether or not the fixing mode can be maintained.

[0085] For example, in the following cases (1) to (4), the CPU72A is unable to maintain the fixing mode and switches to the grease induction mode. (1) When the rotational speed of the fixing belt 142 (or pressure roll 120) reaches a predetermined number (2) When the image forming apparatus 10 has formed a predetermined number of images (3) When a predetermined time has elapsed after image formation by the image forming apparatus 10 (4) When the user (not shown) of the image forming apparatus 10 gives instructions

[0086] If the judgment result is "Y" indicating a positive result, CPU72A proceeds to step S20. In step S20, CPU72A executes the fixing mode. Then, CPU72A terminates the flow.

[0087] On the other hand, if the judgment result is "N" indicating negation, the CPU 72A proceeds to step S30. In step S30, the CPU 72A executes the grease induction mode. The grease induction mode is executed during periods when the fixing mode is not being executed, specifically during periods when image forming is not being performed in the image forming apparatus 10. The grease induction mode is executed, for example, after the fixing mode has finished, specifically after the image forming in the image forming apparatus 10 has finished. Then, the CPU 72A returns the flow to the beginning. Thus, the mode is switched.

[0088] The grease induction mode may also be executed when the image forming apparatus 10 is powered on and started up.

[0089] <Execution of grease induction mode> Next, the execution of the grease induction mode in the controller 70 will be explained with reference to Figure 9.

[0090] When the CPU 72A of the controller 70 starts executing the grease induction mode, in step S32 it operates the contact / disconnection mechanism to put the pressure roll 120 into the relaxed state shown in Figure 5. This increases the dimension LB of the gap X (see Figure 7) while maintaining contact between the pressure roll 120 and the fixing belt 142.

[0091] As mentioned above, the dimension LB of the pressure roll 120 in the relaxed state is larger than the dimension LB in the pressurized state. Also, as mentioned above, the dimension LB of the pressure roll 120 in the relaxed state is larger than the dimension LC between the central portion 144Y of the heater 144 and the fixing belt 142. Then, the CPU 72A proceeds to step S34.

[0092] In step S34, CPU 72A rotates the pressure roll 120 in the -S direction relative to the drive unit. This causes the fixing belt 142 to rotate in the +R direction. As a result, CPU 72A guides the grease G present upstream in the +R direction relative to the upstream portion 144X into the enlarged gap X. Then, CPU 72A proceeds to step S36.

[0093] In step S36, CPU 72A determines whether the rotation time of the pressure roll 120 has exceeded a predetermined reference time. If the determination result is "Y", CPU 72A proceeds to step S38.

[0094] On the other hand, if the judgment result is "N", the CPU 72A proceeds to step S34. The CPU 72A then continues to rotate the pressure roll 120 in the -S direction until the rotation time of the pressure roll 120 has elapsed according to a predetermined reference time.

[0095] The reference time is set as the time required for the grease G, which is located upstream of the upstream portion 144X in the +R direction, to move into the gap X. As an example, the reference time is set to the rotation time required for the fixing belt 142 to make two rotations.

[0096] In step S38, CPU 72A stops the rotation of the pressure roll 120. Then, CPU 72A proceeds to step S40.

[0097] In step S40, CPU 72A operates the contact / disconnection mechanism to pressurize the pressure roll 120 as shown in Figure 4. This pressurizes the pressure roll 120 against the fixing belt 142, forming a fixing nip N. At this time, the grease G guided into the gap X is spread out and supplied to the downstream side in the +R direction. As a result, the grease G spreads over a wide area between the contact area 144S and the fixing belt 142 within the fixing nip N. Then, CPU 72A terminates the process.

[0098] Furthermore, the CPU72A executes the grease induction mode, for example, with the heater 144 stopped. Furthermore, the CPU72A executes the grease induction mode with the heater 144 heated. Induction mode may be executed.

[0099] <effect> Next, the operation of this embodiment will be explained.

[0100] In this embodiment, the CPU 72A performs a grease induction mode in addition to the fixing mode, as described above. Therefore, fixing failures are suppressed compared to a configuration in which the CPU 72A performs only the fixing mode.

[0101] In this embodiment, as described above, the CPU 72A brings the pressure roll 120 and the fixing belt 142 into contact in the grease induction mode. This makes it possible to directly transmit the driving force of the pressure roll 120 to the fixing belt 142.

[0102] In this embodiment, as described above, the CPU 72A rotates the fixing belt 142 in accordance with the rotation of the pressure roll 120 during the relaxation state in the grease induction mode. This eliminates the need for a driving force to drive the fixing belt 142.

[0103] In this embodiment, as described above, the CPU 72A makes the dimension LB of the gap X (see Figure 7) larger than the dimension LB in the pressurized state when in the relaxed state of the grease induction mode. As a result, the grease G can be guided into the gap X when in the relaxed state of the grease induction mode compared to when the dimension LB of the gap X is the same as the dimension LB in the pressurized state. This suppresses poor adhesion.

[0104] In this embodiment, the CPU 72A makes the dimension LB of the gap X (see Figure 7) larger than the dimension LC (see Figure 7) between the central portion 144Y in the +R direction of the contact area 144S and the fixing belt 142 during the relaxation state in the grease induction mode. As a result, during the relaxation state in the grease induction mode, the grease G can be guided into the gap X more effectively than when the dimension LB of the gap X is the same as the dimension LC. This suppresses fixing failures.

[0105] In this embodiment, in grease induction mode, the CPU 72A rotates the fixing belt 142 in the +R direction to guide the grease G present upstream of the upstream portion 144X in the +R direction into the enlarged gap X. As a result, compared to the case where the CPU 72A keeps the grease G present upstream of the upstream portion 144X in the +R direction in grease induction mode, the grease G can be spread over a wider area between the contact area 144S and the fixing belt 142 within the fixing nip N. This suppresses fixing failures.

[0106] In the image forming apparatus 10, as described above, fixing defects are suppressed, and therefore image defects in the image formed on the sheet member P are suppressed.

[0107] <Modified example of grease induction mode> In this embodiment, the CPU 72A is in contact with the pressure roll 120 and the fixing belt 142 in the grease induction mode, but it is not limited to this. The CPU 72A may not be in contact with the pressure roll 120 and the fixing belt 142 in the grease induction mode. In this case, for example, a transmission mechanism for transmitting the driving force of the pressure roll 120 and a drive source for driving the fixing belt 142 are provided separately.

[0108] In this embodiment, the CPU 72A rotates the fixing belt 142 in accordance with the rotation of the pressure roll 120 during the relaxation state in the grease induction mode, but is not limited to this. The CPU 72A may, for example, rotate the fixing belt 142 during the grease induction mode.

[0109] In this embodiment, the CPU 72A made the dimension LB of the gap X (see Figure 7) larger than the dimension LC in the relaxation state in the grease induction mode, but it is not limited to this. For example, the CPU 72A may make the dimension LB of the gap X the same as the dimension LC.

[0110] <Other variations> Although this disclosure has described in detail certain embodiments, it will be apparent to those skilled in the art that this disclosure is not limited to such embodiments and can take various other embodiments within the scope of this disclosure.

[0111] In the above embodiment, an image forming apparatus 10 having the apparatus layout shown in Figure 1 was used for the explanation, but it is not limited thereto. For example, this disclosure is also applicable to image forming apparatuses having a different apparatus layout from that of the image forming apparatus 10. Furthermore, in the above embodiment, the main operating unit 14 was described using a tandem color type, but it is not limited thereto. The main operating unit may be rotary or monochrome. Also, the main operating unit is not limited to an indirect transfer method, but may be a direct transfer method.

[0112] In the above embodiment, the fixing belt 142 is configured to follow the rotation of the pressure roll 120 while the pressure roll 120 is pressed against it, but it is not limited to this configuration. For example, the pressure roll 120 may follow the rotation of the fixing belt 142 while it is pressed against it. Alternatively, the fixing belt 142 itself may be configured to be rotationally driven.

[0113] In the above embodiment, the CPU 72A created the separated state shown in Figure 3, the pressurized state shown in Figure 4, and the relaxed state shown in Figure 5 by moving the pressure roll 120 relative to the fixing belt 142 using a separation mechanism, but it is not limited to this. The CPU 72A may also create the separated state, the pressurized state, and the relaxed state by moving the fixing belt 142, for example, instead of or in addition to moving the pressure roll 120. That is, the CPU 72A can create the separated state, the pressurized state, and the relaxed state by moving at least one of the pressure roll 120 and the fixing belt 142, thereby moving one relative to the other.

[0114] Furthermore, the rotating body of this disclosure is not limited to a pressure roll, but may also be a pressure member such as a pressure drum. Also, the fixing member of this disclosure is not limited to a fixing belt, but may also be a fixing member such as a fixing film. Furthermore, the heating member of this disclosure is not limited to a planar heating element, but may also be a heating member composed of, for example, cylindrical lamps or the like.

[0115] In this embodiment, each process is executed on any computer. Furthermore, any computer may execute these processes using a processor as hardware, a program as software, or a combination thereof. In that case, the processor is configured to work in cooperation with the program to execute the various processes in this embodiment, and can function as a unit or means in this embodiment. Also, the execution order of the processes by the processor is not limited to the order described and may be changed as appropriate. Any computer may be a general-purpose computer, a computer designed for a specific purpose, a workstation, or any other system capable of executing each process.

[0116] A processor may consist of one or more hardware components, and the type of hardware is not limited. For example, a processor may consist of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a programmable logic device such as an FPGA (Field Programmable Gate Array), a dedicated circuit for executing a specific process such as an ASIC (Application Specific Integrated Circuit), a GPU (Graphic Processing Unit), or an NPU (Neural Processing Unit). Furthermore, the type of hardware may be a combination of different types of hardware. When multiple hardware components are configured to execute one or more processes of a processor, these components may reside in physically separate devices or in the same device. Also, in any embodiment, the order of each process performed by the processor is not limited to the order described above and may be changed as appropriate. Hardware is composed of electrical circuits (circuitry) that combine circuit elements such as semiconductor elements.

[0117] Furthermore, the program may be firmware or software such as microcode. Alternatively, the program may be, for example, a group of program modules, each function of which may be implemented by a processor configured to perform its respective function. The program may be program code or multiple code segments stored on one or more non-temporary computer-readable media (e.g., storage media or other storage devices). The program may be divided and stored on multiple non-temporary computer-readable media located on physically separate devices. The program code or code segments may represent any combination of procedures, functions, subprograms, routines, subroutines, modules, software packages, classes, or instructions, data structures, or program statements. The program code or code segments may be connected to other code segments or hardware circuits by sending and receiving information, data, arguments, parameters, or memory contents. The program of this application may also be provided as a program product.

[0118] (Note) (((1))) A rotating body and In a pressurized state where the rotating body applies pressure, an endless fixing member is formed which a clamping region is created that sandwiches the medium between the rotating body and the fixing member, The clamping region has a contact region that contacts the inner circumference of the fixing member via a lubricant containing a thickener, and a heating member that generates heat in the contact region, Processor and Equipped with, The aforementioned processor, In the fixing mode, the fixing member heated by the heating element clamps the medium between itself and the rotating body in the clamping region formed under the pressurized state and rotates in one direction to fix the image on the medium. In the relaxed state, where the pressurized state is relieved, the fixing member rotates in one direction in a rotation mode, Execute Fixing system. (((2))) The aforementioned processor, In the relaxation state in the rotation mode, The rotating body and the fixing member are brought into contact. The fixing system described in (((1))). (((3))) The aforementioned processor, In the relaxation state in the rotation mode, The fixing member is rotated in accordance with the rotation of the rotating body. The fixing system described in (((2))). (((4))) The aforementioned processor, In the relaxation state in the rotation mode, The dimension between the upstream portion in one direction of the contact area of ​​the heating element and the fixing element is, To make it larger than the dimension in the aforementioned pressurized state. The fixing system described in any one of (((1))) to (((3))). (((5))) The aforementioned processor, In the aforementioned rotation mode, By rotating the fixing member in the aforementioned one direction, the lubricant present upstream of the upstream portion in that direction is guided between the upstream portion and the fixing member. The fixing system described in (((4))). (((6))) The aforementioned processor, In the relaxation state in the rotation mode, The dimension between the upstream portion in one direction of the contact area of ​​the heating element and the fixing element is, The dimension between the central portion in one direction of the contact area and the fixing member is made larger. The fixing system described in any one of (((1))) to (((5))). (((7))) The aforementioned processor, In the aforementioned rotation mode, By rotating the fixing member in the aforementioned one direction, the lubricant present upstream of the upstream portion in that direction is guided between the upstream portion and the fixing member. The fixing system described in (((6))). (((8))) An image forming unit that forms an image on a medium, A fixing system according to any one of (((1))) to (((7))) for fixing an image formed on the aforementioned medium, An image forming apparatus equipped with the following features.

[0119] According to the configuration of (((1))), compared to the case where the processor only performs a fixing mode in which a fixing member heated by a heat-generating element clamps the medium between the rotating body and the medium in a clamping region formed under pressure and rotates in one direction to fix the image on the medium, fixing defects are suppressed. According to the configuration of (((2))), the driving force of the rotating body can be directly transmitted to the fixing member. According to the configuration of (((3))), a driving force is not required to drive the fixing member. According to the configuration of (((4))), when the processor is in a relaxed state in rotation mode, fixing failures are suppressed compared to when the dimension between the unidirectional upstream portion of the contact area and the fixing member is the same as the dimension in the pressurized state. According to the configuration of (((5))), in the rotation mode, the processor suppresses poor adhesion compared to the case where the lubricant present in one direction upstream of the upstream portion is kept in that upstream position. According to the configuration of (((6))), when the processor is in a relaxed state in rotation mode, fixing failures are suppressed compared to when the dimension between the upstream portion in one direction of the contact area and the fixing member is the same as the dimension in the central portion. According to the configuration of (((7))), in the rotation mode, the processor suppresses poor adhesion compared to the case where the lubricant present upstream in one direction relative to the upstream portion is kept upstream. According to the configuration of (((8))), image defects are suppressed compared to when the processor only performs a fixing mode in which a fixing member heated by a heat-generating element clamps the medium between the rotating body and the medium in a clamping region formed under pressure, and rotates in one direction to fix the image on the medium. [Explanation of Symbols]

[0120] 10 Image forming apparatus 10a Main unit of the device 12 Storage Unit 14 Main operating part 16. Manuscript Reading Unit 18 Conveying section 22. First containment unit 24 Second Detention Unit 26 Third Detention Unit 28. Fourth Detention Unit 30. Transport Route 31 Double-sided transport route 31a Switchback road 32 Dispensing Rolls 33 Hand-pointed path 34 Double-feed prevention roll 36 Conveyor Rolls 38 Conveying device 40 Display section 42 Charger 44 Developer 46 Cleaning parts 48 Transfer Belt 50 Primary Transfer Rolls 52 Secondary transfer roll 54 Auxiliary Rolls 56 rolls 60 Image forming unit 62 Photoconductor Drum 64 Image forming unit 66 Exposure equipment 68 Transfer Unit 70 Controllers 72A CPU (an example of a processor) 72D Storage 72E Bus 74 Input / output section 76 Network Interface 80 Discharge section 90 Fixing System 100 Fixing device 120 Pressure Roll (Example of a Rotating Body) 122 Elastic layer 124 Mandrel 126 Release layer 140 Heating section 142 Fixing belt 144 Heater (an example of a heating element) 144S contact area 144X upstream part 144Y center part 146 pads 146A Downstream end 146B Upstream end 146C recess 148 Support member CV transport direction G Grease N Fixing Nip P sheet material (an example of a medium) T transcription position

Claims

1. A solid of rotation and In a pressurized state where the rotating body applies pressure, an endless fixing member is formed which a clamping region is created that sandwiches the medium between the rotating body and the fixing member, The clamping region has a contact region that contacts the inner circumference of the fixing member via a lubricant containing a thickener, and a heating member that generates heat in the contact region, Processor and Equipped with, The aforementioned processor, In the fixing mode, the fixing member heated by the heating element clamps the medium between itself and the rotating body in the clamping region formed under the pressurized state and rotates in one direction to fix the image on the medium. In the relaxed state, where the pressurized state is relieved, the fixing member rotates in one direction in a rotation mode, Execute Fixing system.

2. The aforementioned processor, In the relaxation state in the rotation mode, The rotating body and the fixing member are brought into contact. The fixing system according to claim 1.

3. The aforementioned processor, In the relaxation state in the rotation mode, The fixing member is rotated in accordance with the rotation of the rotating body. The fixing system according to claim 2.

4. The aforementioned processor, In the relaxation state in the rotation mode, The dimension between the upstream portion in one direction of the contact area of ​​the heating element and the fixing element is, To make it larger than the dimension in the aforementioned pressurized state. The fixing system according to claim 1.

5. The aforementioned processor, In the aforementioned rotation mode, By rotating the fixing member in the aforementioned one direction, the lubricant present upstream of the upstream portion in that direction is guided between the upstream portion and the fixing member. The fixing system according to claim 4.

6. The aforementioned processor, In the relaxation state in the rotation mode, The dimension between the upstream portion in one direction of the contact area of ​​the heating element and the fixing element is, The dimension between the central portion in one direction of the contact area and the fixing member is made larger. The fixing system according to claim 1.

7. The aforementioned processor, In the aforementioned rotation mode, By rotating the fixing member in the aforementioned one direction, the lubricant present upstream of the upstream portion in that direction is guided between the upstream portion and the fixing member. The fixing system according to claim 6.

8. An image forming unit that forms an image on a medium, A fixing system according to any one of claims 1 to 7 for fixing an image formed on the medium, An image forming apparatus equipped with the following features.

Images