JP2014174358A - Fixing device and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve slidability of a fixing belt to extend the life of a fixing device.SOLUTION: A rotatable fixing belt 104 (fixing member) heated by a halogen heater 116 (heat source) and held by a flange 114 (holding member) at both right and left ends is applied with pressure by a pressure roller 102 (pressure member). Inside the fixing belt 104, the pressure roller 102 forms a nip part 122 with a nip forming member 106, and between the nip forming member 106 and the fixing belt 104, a cloth-like slide sheet 108b (slide member) is installed, which contains lubricant 112 and is molded so that a fiber recessed groove direction 130b (groove direction) becomes identical to a slide direction of the fixing belt 104. A lubricant circulation member 110a holds the lubricant 112 to be applied to the slide sheet 108b on the upstream side of the nip part 122, and applies the lubricant 112 to the fixing belt 104 to supply the lubricant 112 to the downstream side of the nip part 122.

Description

  The present invention relates to a fixing device capable of extending the life of a fixing device by improving the slidability of the fixing belt, and an image forming apparatus including the fixing device.

  An electrophotographic image forming apparatus forms an electrostatic latent image on the surface of a photosensitive drum, which is an image carrier, and develops the electrostatic latent image on the photosensitive drum with a developer such as toner to visualize it. The toner image is transferred onto the recording paper by the transfer device, and the toner image on the recording paper is fixed by applying heat and pressure to the recording paper after the transfer with the fixing device. Is discharged to the outside of the apparatus.

  The fixing device is usually composed of a pair of opposed heating rollers and pressure rollers, or a fixing belt, or a combination thereof. The conveyed recording paper is placed between the heating roller and the pressure roller. The toner image is fixed on the recording paper by applying heat and pressure while the recording paper is passing through the nip.

  In such a fixing device, it is necessary to improve the slidability of the fixing belt in order to prevent the recording paper from being jammed. For this reason, a configuration in which a lubricating sheet coated with a lubricant is interposed so as to be in contact with the fixing belt has been proposed (for example, Patent Document 1).

  However, in the configuration described in Patent Document 1, as the fixing device continues to operate, the lubricant impregnated in the lubricating sheet is pressed and squeezed by the pressure roller, and the squeezed lubrication is performed. The agent improves the slidability of the fixing belt by permeating from the upstream side of the nip to the downstream side of the nip, but part of the lubricant reaching the downstream side of the nip leaks without being collected. In addition, a part of the lubricant circulates while adhering to the fixing belt, and is collected on the lubricating sheet and re-applied to the fixing belt. The lubricating sheet has taken into consideration the recovery and re-application of the lubricant. Since it is not structured, there is a possibility that the lubricant cannot be sufficiently collected and applied due to the occurrence of wear of the lubricating sheet. Therefore, there is a problem that there is a limit to the period during which the lubricating effect by the lubricant can be exhibited.

  The present invention has been made in view of the above circumstances, and an object thereof is to improve the slidability of the fixing belt over a longer period of time.

  The fixing device and the image forming apparatus according to the present invention improve the slidability of the fixing belt constituting the fixing device, thereby preventing an increase in torque when the fixing belt is moved, thereby extending the life of the fixing device. Is intended.

  That is, a fixing device according to claim 1 of the present invention is a rotatable fixing member formed of an endless belt, a heating source for heating the fixing member, and pressurization for forming a nip portion by pressurizing the fixing member. A member, a nip forming member that forms a nip opposite to the pressure member inside the fixing member, and a fiber weave that contains a lubricant and is disposed between the nip forming member and the fixing member. A cloth-like sliding member formed so that the groove direction is the same as the rotation direction of the fixing member, a support member that supports the nip forming member, and a holding member that holds both right and left ends of the fixing member; A lubricant circulation member that holds the lubricant on the upstream side of the nip of the sliding member and supplies the lubricant to the downstream side of the nip by attaching the lubricant to the fixing member. And wherein the door.

  In the fixing device according to the first aspect of the present invention configured as described above, the rotatable fixing member, which includes the endless belt heated by the heating source and is held by the holding members at the left and right ends, is provided by the pressure member. By being pressurized, a nip is formed inside the fixing member at a position facing the pressure member and between the nip forming member supported by the support member and the pressure member. Lubricating a cloth-like sliding member installed between the member and the fixing member, which contains a lubricant and is shaped so that the groove direction caused by the fiber weave is the same as the sliding direction of the fixing member The agent circulation member holds the lubricant to be attached to the sliding member on the upstream side of the nip, and attaches the lubricant to the fixing member and supplies the lubricant to the downstream side of the nip. Molded to match the direction By being supplied along the groove direction of the sliding member, it is possible to prevent the outflow of lubricant from the side edge position of the sliding member to the outside. Further, when the fixing member that has circulated while the lubricant is adhered contacts the lubricant circulating member again, the lubricant can be collected on the lubricant circulating member and the lubricant can be reapplied. As a result, the slidability of the fixing member is improved over a long period of time, and an increase in torque when the fixing belt is moved can be prevented, so that the life of the fixing device can be extended.

  According to the fixing device and the image forming apparatus according to the present invention, since the slidability of the fixing belt constituting the fixing device is improved, it is possible to prevent an increase in torque when the fixing belt is moved. Life can be extended.

1 is a diagram illustrating a schematic configuration of a color printer including a fixing device according to Embodiment 1. FIG. 1 is a diagram illustrating a structure of a fixing device according to Embodiment 1. FIG. (A) is a figure shown about the structure of a plain weave among the typical weaving methods of the fiber which comprises the sliding member which concerns on Example 1. FIG. (B) is a figure shown about a twill structure among the typical weaving methods of the fiber which comprises the sliding member which concerns on Example 1. FIG. 1 is a diagram illustrating a structure of a sliding member according to Example 1. FIG. (A) is a figure which shows the effect | action of a sliding member in case Example 1 is not applied. (B) is a figure which shows the effect | action of a sliding member at the time of Example 1 being applied. FIG. 6 is a diagram illustrating an operation of the fixing device according to the first exemplary embodiment. It is a figure which shows another structure of the lubricant circulation member which concerns on Example 1. FIG. FIG. 10 is a diagram illustrating an operation of the fixing device according to the second embodiment.

  Hereinafter, a first embodiment of a fixing device and an image forming apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram illustrating a color printer as an image forming apparatus including a fixing device according to Embodiment 1 of the present invention. First, the overall configuration and operation of a color printer 1 that is one embodiment of an image forming apparatus including a fixing device will be described.

  (Description of Configuration and Operation of Color Printer) The color printer 1 (image forming apparatus) shown in FIG. 1 uses a tandem system in which image forming units for forming a plurality of color images are juxtaposed along the belt extending direction. There is a color printer. However, the present invention is not limited to this method, and can be applied not only to a printer but also to a copying machine, a facsimile machine, and the like.

  In FIG. 1, a color printer 1 (image forming apparatus) forms an image as an image corresponding to each color separated into yellow, cyan, magenta, and black. Therefore, a tandem structure in which photosensitive drums 20Y, 20C, 20M, and 20Bk as image carriers are arranged in parallel is employed.

  In the color printer 1 shown in FIG. 1, the visible images formed on the photosensitive drums 20Y, 20C, 20M, and 20Bk move in the direction of the arrow A1 against the photosensitive drums 20Y, 20C, 20M, and 20Bk. A primary transfer process is performed on the intermediate transfer body 11 (hereinafter referred to as the transfer belt 11) using an endless belt. Then, each image is superimposed and transferred, and then transferred to the paper S by performing a secondary transfer process.

  Around each of the photosensitive drums 20Y, 20C, 20M, and 20Bk, an apparatus for image forming processing is arranged according to the rotation of the photosensitive drum. For example, the photosensitive drum 20Bk that performs black image formation will be described. A charging device 30Bk, a developing device 40Bk, a primary transfer roller 12Bk, and a cleaning device 50Bk that perform image forming processing along the rotation direction of the photosensitive drum 20Bk are arranged. ing. Writing performed after charging is performed by the optical writing device 8.

  In the superimposing transfer to the transfer belt 11, the visible image formed on each of the photoconductive drums 20 </ b> Y, 20 </ b> C, 20 </ b> M, and 20 </ b> Bk is superimposed on the same position on the transfer belt 11 in the process in which the transfer belt 11 moves in the direction of arrow A <b> 1. It is done to be transcribed. This transfer is performed from the upstream side in the A1 direction by applying a voltage from the primary transfer rollers 12Y, 12C, 12M, and 12Bk disposed opposite to the photosensitive drums 20Y, 20C, 20M, and 20Bk with the transfer belt 11 interposed therebetween. The timing is shifted toward the downstream side.

  The photosensitive drums 20Y, 20C, 20M, and 20Bk are arranged in this order from the upstream side in the arrow A1 direction. Each of the photosensitive drums 20Y, 20C, 20M, and 20Bk is provided in an image station for forming yellow, cyan, magenta, and black images.

  The color printer 1 (image forming apparatus) is arranged to face four image stations that perform image forming processing for each color, and above the respective photosensitive drums 20Y, 20C, 20M, and 20Bk. The transfer belt unit 15 includes a transfer belt 11 and primary transfer rollers 12Y, 12C, 12M, and 12Bk, and a transfer member that is disposed so as to face the transfer belt 11 and that is driven by the transfer belt 11. A secondary transfer roller 5. Further, an intermediate transfer belt cleaning device 13 (hereinafter referred to as a cleaning device) that is disposed facing the transfer belt 11 and cleans the transfer belt 11, and disposed below these four image stations. The optical writing device 8 is provided.

  The optical writing device 8 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygon mirror as a deflecting means, and the like. Writing light Lb corresponding to each color is emitted to each of the photosensitive drums 20Y, 20C, 20M, and 20Bk to form an electrostatic latent image on the photosensitive drums 20Y, 20C, 20M, and 20Bk. In FIG. 1, for the sake of convenience, reference numerals are given only to the image stations for black images, but the same applies to other image stations.

  The color printer 1 (image forming apparatus) includes a sheet feeding device 61 as a sheet feeding cassette on which sheets S conveyed toward the transfer belt 11 are placed between the photosensitive drums 20Y, 20C, 20M, and 20Bk. . Further, the transfer section between each of the photosensitive drums 20Y, 20C, 20M, and 20Bk and the transfer belt 11 at a timing that matches the formation timing of the toner image by the image station with the sheet S conveyed from the sheet feeding device 61. A registration roller pair 4 that is fed out toward the end. Furthermore, a sensor (not shown) that detects that the leading edge of the sheet S has reached the registration roller pair 4 is provided.

  The color printer 1 (image forming apparatus) further includes a roller fixing type fixing device 100 for fixing the toner image onto the sheet S on which the toner image is transferred, and the fixed sheet S to the color printer 1 (image forming apparatus). And a paper discharge roller 7 for discharging to the outside of the main body. In addition, the color printer 1 (image forming apparatus) includes a paper discharge tray 17 that is disposed on the top of the main body and stacks sheets S discharged outside the main body of the color printer 1 (image forming apparatus). Further, toner bottles 9Y, 9C, 9M, and 9Bk are provided below the paper discharge tray 17 and filled with toners of yellow, cyan, magenta, and black.

  The fixing device 100 includes a pressure roller 102 that is a pressure member, and a fixing belt 104 that is a fixing member composed of a flexible endless belt. Then, the unfixed sheet S on which the toner image is transferred is passed through a nip portion 122 (see FIG. 2) formed at a contact portion between the pressure roller 102 (pressure member) and the fixing belt 104 (fixing member). As a result, the unfixed image is fixed by heat and pressure. A detailed configuration of the fixing device 100 will be described later.

  In addition to the transfer belt 11 and the primary transfer rollers 12Y, 12C, 12M, and 12Bk, the transfer belt unit 15 includes a driving roller 72 and a driven roller 73 around which the transfer belt 11 is wound.

  The driven roller 73 also has a function as a tension urging unit for the transfer belt 11. For this reason, the driven roller 73 is provided with an urging unit using a spring or the like. Such a transfer belt unit 15, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, the secondary transfer roller 5, and the cleaning device 13 constitute a transfer device 71.

  The sheet feeding device 61 is disposed at the lower part of the main body of the color printer 1 (image forming apparatus). The uppermost sheet S has a feeding roller 3 as a sheet feeding roller that abuts on the upper surface of the uppermost sheet S, and the uppermost sheet S is registered by rotating the feeding roller 3 counterclockwise. It feeds toward the roller pair 4.

  The cleaning device 13 provided in the transfer device 71 has a cleaning brush and a cleaning blade (not shown) that are disposed so as to abut against the transfer belt 11. The transfer belt 11 is cleaned by scraping and removing foreign matters such as residual toner on the transfer belt 11 with a cleaning brush and a cleaning blade.

  The cleaning device 13 further includes a discharge unit (not shown) for carrying out and discarding the residual toner removed from the transfer belt 11.

(Description of fixing device configuration and operation)
Next, a detailed configuration and operation of the fixing device 100 as a fixing unit provided in the color printer 1 (image forming apparatus) will be described with reference to FIG.

  The fixing device 100 includes a pressure roller 102 (pressure member) and a fixing belt 104 (fixing member). The fixing belt 104 (fixing member) is directly radiated from the inner peripheral side by a halogen heater 116 (heating source). Heated.

The fixing belt 104 (fixing member) includes a pressure roller 102 (rotating in a rotation direction R ₁ ) at a nip portion 122 formed at a contact portion between the pressure roller 102 (pressure member) and the nip forming member 106. with the rotation of the pressure member) is moved while rotating in the direction of the rotation direction R _2. The inner surface of the fixing belt 104 (fixing member) slides through a sliding sheet 108b (sliding member) installed on the surface of the nip forming member 106.

  In FIG. 2, since the nip portion 122 has a concave shape, the discharge direction at the front end of the paper is closer to the pressure roller 102 (pressure member) and the separation is improved, so that a paper jam (jam) occurs. Is suppressed. However, the shape of the nip portion 122 is not limited to the concave shape, and may be a flat shape or other shapes.

  The fixing belt 104 (fixing member) is an endless belt (or film) using a metal belt such as nickel or SUS or a resin material such as polyimide. The surface layer of the fixing belt 104 (fixing member) has a release layer made of a fluorinated resin such as PFA or PTFE, and has a release property so that toner does not adhere. There may be an elastic layer formed of a silicon rubber layer or the like between the belt substrate and the PFA or PTFE layer. In the absence of the silicone rubber layer, the heat capacity is reduced and the fixability is improved. However, when the unfixed image is crushed and fixed, minute irregularities on the surface of the fixing belt 104 (fixing member) are transferred to the image. There is a problem in that a glossy unevenness (skin skin image) remains on the solid portion. In order to improve this, it is necessary to provide a silicon rubber layer of 100 [μm] or more. Due to the deformation of the silicon rubber layer, fine irregularities are absorbed and the skin image is improved.

  In addition to the above, as the base material of the fixing belt 104 (fixing member), a heat-resistant resin such as a fluorine resin, a polyamide resin, a polyamideimide resin, a PEEK resin, a PES resin, or a PPS resin may be used. .

  A stay 120 (support member) for supporting the nip portion 122 is provided inside the fixing belt 104 (fixing member), and the nip forming member 106 that receives pressure by the pressure roller 102 (pressure member) is bent. To prevent. This makes it possible to obtain a uniform nip width in the width direction of the fixing belt 104 (fixing member). The stay 120 (support member) is positioned by being held and fixed to the flange 114 (holding member) at both ends thereof. Further, a reflecting member 118 is provided between the halogen heater 116 (heating source) and the stay 120 (supporting member), and the stay 120 (supporting member) is heated by radiation heat from the halogen heater 116 (heating source) or the like. Controlling unnecessary energy consumption. Here, instead of providing the reflecting member 118, the same effect can be obtained even if the surface of the stay 120 (supporting member) is heat-insulated or mirror-finished.

  As a heating source, IH may be used instead of the halogen heater 116 (heating source), a resistance heating element, a carbon heater, or the like may be used. In the embodiment of FIG. 2, three halogen heaters 116 are used as a heat source. However, the number is not limited to three. Considering the amount of heat given to the fixing belt 104 (fixing member), An appropriate heating source may be designed.

  The pressure roller 102 (pressure member) includes a cored bar 102a and an elastic rubber layer 102b provided on the outer side of the core metal 102a. Further, the surface of the elastic rubber layer 102b is separated from the surface in order to obtain releasability. A mold layer (PFA or PTFE layer) is formed. The pressure roller 102 (pressure member) is rotated by a driving force transmitted through a gear from a driving source such as a motor provided in the color printer 1 (image forming apparatus) (not shown). Further, the pressure roller 102 (pressure member) is pressed against the fixing belt 104 (fixing member) side by a spring (not shown), and the elastic rubber layer 102b is crushed and deformed, whereby a predetermined nip is formed. It has a width. The pressure roller 102 (pressure member) may be a hollow roller, or may have a heating source such as a halogen heater inside the pressure roller 102 (pressure member). The elastic rubber layer 102b may be solid rubber, but sponge rubber may be used when there is no heat source inside the pressure roller 102 (pressure member). The use of sponge rubber is more preferable because the heat insulating property is improved and the heat of the fixing belt 104 (fixing member) is less likely to be taken away.

The fixing belt 104 (fixing member) is rotated by the pressure roller 102 (pressure member). In the case of FIG. 2, the pressure roller 102 (pressure member) is rotated in the rotation direction R ₁ by a driving source (not shown), and the driving force is transmitted to the fixing belt 104 (fixing member) through the nip portion 122. fixing belt 104 (fixing member) is moved while rotating in the direction of the rotational direction _{R 2.} The fixing belt 104 (fixing member) is nipped at the nip portion 122 and rotates, and the other end portion of the fixing belt 104 (fixing member) travels while being guided by the flange 114 (holding member).

  A lubricant circulating member 110a that absorbs and re-applies the lubricant 112 is disposed on the upstream side of the fixing belt 104 (fixing member) in the traveling direction (upstream of the nip portion 122). The lubricant lubrication member 110a is configured by winding a sheet-like material having functions of heat resistance and oil retention and is impregnated with a lubricant 112 such as silicon oil. Yes.

  The paper (recording paper) S to which the toner image has been transferred is conveyed to the fixing device 100 along the paper passing direction S1, and is pressurized and heated by passing through the nip portion 122, whereby the toner image is fixed on the paper S. The sheet is discharged from the fixing device 100.

(Description of the operation of the first embodiment)
Next, the operation of the first embodiment will be described with reference to FIGS.

  In FIG. 2, a sliding sheet 108b (sliding member) is affixed at a location where the nip forming member 106 contacts and slides with the fixing belt 104 (fixing member). The sliding sheet 108b (sliding member) is made of a cloth-like material made of fibers having heat resistance such as PFA and PTFE, low friction and high releasability. By attaching a lubricant 112 such as silicon oil soaked in the lubricant circulating member 110a to the sliding belt 108b (sliding member), the sliding belt 108b (sliding member) is attached to the moving fixing belt 104 (fixing member). Apply. The lubricant 112 applied in this way moves to the surface of the sliding sheet 108b (sliding member) as the fixing belt 104 (fixing member) moves.

  The structure of the fibers constituting the sliding sheet 108b (sliding member) will be described with reference to FIGS. 3 (a) and 3 (b). The method for forming fibers into a cloth form is roughly divided into a plain weave method shown in FIG. 3A and a twill weave method shown in FIG. 3B. Among these, it is the twill weave structure shown in FIG. 3B that can increase the fiber strength and the basis weight (density). This twill structure is suitable for the sliding sheet 108b (sliding member) that requires strength and wear resistance.

  However, the twill weave is a weaving method in which the intersecting position of the warp and weft is gradually shifted from the left and right yarns. Therefore, when viewed macroscopically, oblique irregularities (crests and grooves) are generated on the surface.

  As shown in FIG. 4, the sliding sheet (sliding member) has a predetermined direction in which the unevenness (crests and grooves) formed by fiber weaving (hereinafter referred to as fiber concave groove direction 130a (groove direction)). It is installed on the surface of the nip forming member 106 in a state of facing. In the example of FIG. 4, the fiber concave groove direction 130a (groove direction) of the sliding sheet 108a (sliding member) is directed obliquely upward to the right with respect to the sheet passing direction S1. As will be described later, the lubricant 112 (not shown) uses the capillary phenomenon of the sliding sheet 108a (sliding member) to slide the sliding sheet 108a (sliding member) along the fiber groove direction 130a. It penetrates and is held evenly throughout.

Next, the flow of the lubricant 112 (not shown) during actual paper feeding will be described with reference to FIGS. Against the nip formation member 106, the conveying direction of the sheet S is in the direction indicated by the feed direction S _1. Accordingly, the fixing belt 104 (fixing member) (not shown) is similarly configured to move from the bottom of the sheet of FIG. 5A to the top of the sheet while contacting the sliding sheet 108a (sliding member).

  In the case of FIG. 5A, when a pressure is applied to the nip forming member 106 by a pressure roller 102 (pressure member) (not shown), the lubricant 112 (not shown) is moved from the lower side to the upper side. Then, the fiber moves obliquely upward from the left side to the right side of the paper along the fiber concave groove direction 130a (groove direction). That is, the fixing belt 104 (fixing member) moves in a direction in which pressure is applied to the sliding sheet 108a (sliding member) from the bottom to the top of the page, so that the sliding sheet 108a (sliding member) penetrates. The lubricant 112 (not shown) receives a force from the bottom to the top so as to be squeezed. Therefore, the lubricant 112 (not shown) moves in the lubricant moving direction 132a indicated by the arrow in FIG. 5A along the fiber groove direction 130a (groove direction) of the sliding sheet 108a (sliding member). To do. Then, the lubricant 112 (not shown) that has reached the lateral end position P of the sliding sheet 108a (sliding member) flows out of the sliding sheet 108a (sliding member). Then, when the lubricant 112 (not shown) flows out, the lubricating performance of the sliding sheet 108a (sliding member) is lowered.

On the other hand, FIG. 5 (b), which shows the configuration of the first embodiment according to the present invention, the sliding sheet 108b (the sliding member), the fiber groove direction 130b (groove direction) feed direction _{S 1} It was installed to match. In this manner, by the fiber groove direction 130b of the sliding sheet 108b (sliding member) (the groove direction) coincides with the paper feeding direction _{S 1,} the lubricant 112 (not shown) sliding sheet 108b (sliding It moves along the fiber groove direction 130b (groove direction) of the moving member. That is, the lubricant (not shown) moves along the lubricant moving direction 132b. Therefore, it is possible to prevent the lubricant 112 (not shown) from flowing out from the lateral end position P of the sliding sheet 108b (sliding member). As a result, the lubricating performance of the sliding sheet 108b (sliding member) can be maintained, and an increase in the amount of wear and an increase in torque due to lubricant depletion can be prevented.

  Next, the actual flow of the lubricant will be described with reference to FIG.

The nip forming member 106 is made of a heat resistant resin such as LCP, PEEK, or PAI. A sliding sheet 108b (sliding member) made of fibers such as PFA and PTFE is wound around the outer periphery, and is fixed by a metal fitting (not shown). A heat-resistant lubricant such as silicon oil is uniformly applied to the sliding sheet 108b (sliding member). Pressure roller 102 (pressing member) is rotated in the direction of the rotational direction R ₁ by the driving force from the outside, by the surface friction between the pressure roller 102 (pressing member) and the fixing belt 104 (fixing member) fixing belt 104 (fixing member) is rotated in the direction of the rotational direction _{R 2.} At this time, if the frictional force (torque) generated between the inner surface of the fixing belt 104 (fixing member) and the nip forming member 106 is larger than the aforementioned surface frictional force, the inner surface of the fixing belt 104 (fixing member) Since it is caught by the forming member 106, it does not rotate smoothly.

  Therefore, in order to prevent wear of the sliding sheet 108b (sliding member) and the inner surface of the fixing belt 104 (fixing member), the above-described lubricant 112 is impregnated in the sliding sheet 108a (sliding member), thereby fixing. The belt 104 (fixing member) is configured to rotate smoothly. Therefore, in the configuration of FIG. 2, when the lubricant 112 is depleted, the fixing belt 104 (fixing member) does not rotate smoothly, causing problems such as a paper jam (jam).

  The lubricant 112 adhering to the fixing belt 104 (fixing member) rotates together with the fixing belt 104 (fixing member). The lubricant 112 that has returned to the nip 122 again is absorbed by the sliding sheet 108b (sliding member) or remains attached to the fixing belt 104 (fixing member) and continues to rotate. Then, the lubricant 112 blocked at the upstream (inlet part) of the nip portion 122 moves in the direction from the front side to the back side in FIG. 2 while adhering to the fixing belt 104 (fixing member). A part of the lubricant 112 flows out from the lateral end position P (see FIG. 5A) of the fixing belt 104 (fixing member) to the outside.

  In order to prevent the lubricant 112 from flowing out, it is possible to prevent the lubricant 112 from flowing out by increasing the viscosity of the lubricant 112. However, when the viscosity of the lubricant 112 is increased, the torque at the sliding portion increases and there is a risk that the load on the device side increases, which is not a desirable measure.

  Furthermore, although it is the sliding sheet 108a (sliding member), since the fluororesin such as PFA and PTFE is a material having a relatively low hardness, heat, pressure, and sliding are applied to the nip portion 122 for a long period of time. If it continues, the fiber eyes (unevenness) may gradually collapse. In addition, it has been confirmed that the fluorine-based resin is stretched and spread to form a film on the surface of the sliding surface. For this reason, the lubricant 112 impregnated in the sliding sheet 108a (sliding member) cannot flow out to the sliding surface, and is changed from fluid lubrication to boundary lubrication, and performance related to sliding is lowered. It will contribute.

  In order to prevent such a problem, in the configuration of FIG. 2, lubrication is performed upstream of the nip forming member 106 in the running direction of the fixing belt 104 (fixing member) (upstream of the nip portion 122). A lubricant circulating member 110a for absorbing and re-applying the agent 112 is disposed.

  The lubricant circulating member 110a may have any heat resistance and oil retaining function, and is the same fiber body of PFA and PTFE that are fluorinated resins as the sliding sheet 108b (sliding member). Alternatively, a non-woven fabric such as felt may be used. In the case of a fibrous body, the holding force of the lubricant 112 may be increased by increasing the volume by wrapping the material body in layers in accordance with the space. The lubricant circulating member 110a may be pressed against the fixing belt 104 (fixing member) by an urging member such as a leaf spring, or may be pressed against the fixing belt 104 (fixing member) by the elastic force of the fibrous body or felt. Good.

  FIG. 6 is a perspective view of the nip forming member 106 and the lubricant circulating member 110a of the fixing device 100 having the configuration of FIG. 2 as viewed from the pressure roller 102 (pressure member) side.

  The lubricant circulating member 110a is composed of the same PFA and PTFE fiber bodies as the sliding sheet 108b (sliding member), and is arranged at the substantially central portion of the fixing belt 104 (fixing member) with two lubricant circulating members 110b, 110c.

  Then, the fiber groove direction 140a (groove direction) of the lubricant circulation member 110b and the fiber groove direction 140b (groove direction) of the lubricant circulation member 110c are respectively relative to the traveling direction of the fixing belt 104 (fixing member). Therefore, it is directed to the center side of the fixing belt 104 (fixing member). That is, the fiber concave groove directions 140 a and 140 b (groove direction) are directed toward the center line in the longitudinal direction of the nip portion 122 from the upstream side to the downstream side of the nip portion 122. Therefore, the lubricant (not shown) that has permeated along the fiber groove direction 140a, 140b of the lubricant circulating member 110a is symmetrical to the center line of the fixing belt 104 (fixing member) and is directed toward the center line. To be applied. Therefore, leakage of the lubricant from the left and right ends of the fixing belt 104 (fixing member) can be prevented. Further, when the lubricant applied to the fixing belt 104 (fixing member) penetrates into the sliding sheet 108b (sliding member), the left and right ends of the sliding sheet 108b (sliding member) (FIG. 5A). Can be prevented from leaking out from the lateral end position P).

  The lubricant circulating member 110a is made of a PFA or PTFE fiber body, which is a fluorinated resin, having heat resistance and oil retention. Therefore, even when the fixing belt 104 (fixing member) heated by the halogen heater 116 (heating source) slides on the lubricant circulating member 110a for a long period of time, the fixing belt 104 (fixing member) Slidability can be maintained.

  FIG. 7 is another configuration example of FIG. 2, and the fixing device 100b is configured as a sliding sheet 108c (sliding member) by integrating the sliding sheet 108b (sliding member) and the lubricant circulating member 110a. It is an example. As described above, since the structure is simplified by integrating the sliding sheet 108b (sliding member) and the lubricant circulating member 110a, the assembling property of the fixing device 100b is improved. Further, since the lubricant 112 impregnated in the sliding sheet 108c (sliding member) gradually permeates the fixing belt 104 (fixing member), the holding amount of the lubricant 112 can be increased.

  Next, a second embodiment of the fixing device and the image forming apparatus according to the present invention will be described with reference to FIG.

  FIG. 8 is an enlarged view of the nip portion 122 and the sliding sheet 108d (sliding member) of the fixing device 100c according to the second embodiment of the present invention. The sliding sheet 108 d (sliding member) is wound around the nip forming member 106 counterclockwise from the base point 142 and is fixed to the nip forming member 106 by a fixing plate 134 and a screw 136. For example, silicon oil or fluorine oil is uniformly impregnated in advance as a lubricant in the sliding sheet 108d (sliding member). In order to prolong the service life, the lubricant holding amount may be increased by sandwiching the lubricant holding member 138 impregnated with the lubricant between the fixing plate 134 and the nip forming member 106.

  The other end of the base point 142 of the sliding sheet 108d (sliding member) is fixed to the cored bar 144 and becomes a wound rotating body, which constitutes the lubricant circulating member 110d. Note that both ends of the core metal 144 are rotatably held by bearing members (not shown). Further, the core metal 144 is brought into contact with the inner surface of the fixing belt 104 (fixing member) at a contact point Q by a biasing member 146 via a bearing member (not shown), and the pressing force of the biasing member 146 includes the contact point Q. A region having a corresponding area is in contact with the inner surface of the fixing belt 104 (fixing member). At this time, the lubricant circulating member 110d is brought into contact with the fixing belt 104 (fixing member) with a pressure lower than that of the sliding sheet 108d (sliding member).

  As described above, the lubricant circulating member 110d is always in contact with the fixing belt 104 (fixing member) to apply the lubricant to the fixing belt 104 (fixing member) and adhere to the inner surface of the fixing belt 104 (fixing member). It has the role of collecting the lubricant that has circulated around.

Furthermore, a force that rotates counterclockwise around the cored bar 144 acts on the sliding sheet 108d (sliding member) as the fixing belt 104 (fixing member) rotates due to the frictional resistance thereof. Then, the sliding sheet 108d (sliding member), the force to stretch sliding sheet 108d (the sliding member) in the direction of arrow _{R 3} is applied.

Lubricant contained in the lubricant circulation member 110d because the sliding sheet 108d (sliding member) decreases the voids between the fibers by being stretched in the direction of arrow R _3, squeezed in the density between the fibers increases It flows out onto the surface of the sliding sheet 108d (sliding member). The lubricant that has flowed out is dropped along the fibers of the sliding sheet 108d (sliding member) by its own weight, reaches the lubricant circulating member 110d, and is applied to the fixing belt 104 (fixing member).

  Further, since the fixing belt 104 (fixing member) and the lubricant circulating member 110d always abut against each other due to the pressing force generated by the urging member 146, the PFA and PTFE fibers wear with the passage of the service period, and the fiber mesh is crushed. As a result, the outflow of the lubricant on the surface is easily inhibited. Then, since the friction coefficient between the fixing belt 104 (fixing member) and the lubricant circulating member 110d increases, the counterclockwise rotational force about the core metal 144 increases, and the tensile force of the lubricant circulating member 110d increases. To do. Therefore, more lubricant can flow out over a long period of time, and it is possible to prevent lubricant depletion due to a change in the surface properties of the lubricant circulation member 110d.

  In the second embodiment, the lubricant circulating member 110d is in contact with the fixing belt 104 (fixing member) with a lower pressure than the sliding sheet 108d (sliding member), and therefore the lubricant circulating member 110d. The occurrence of wear can be prevented. Therefore, the recovery and application of the lubricant by the lubricant circulating member 110d can be stably performed over a long period of time.

  In Example 2 shown in FIG. 8, a part of the sliding sheet 108d (sliding member) is configured as the lubricant circulating member 110d. However, the sliding sheet 108d (sliding member) and the lubricant circulating member 110d are Needless to say, it may be configured as another member.

  That is, one end of the lubricant circulating member 110d is attached to the position of the base point 142 so as to overlap the sliding sheet 108d (sliding member) wound around the surface of the nip forming member 106, and the other end is As shown in FIG. 8, it is good also as a form fixed and wound around the metal core 144. FIG. Thus, even if the sliding sheet 108d (sliding member) and the lubricant circulating member 110d are configured as separate members, the same effects as described in the second embodiment can be obtained.

As described above, in the fixing device 100 according to the first embodiment of the present invention, the rotatable fixing belt 104 (heated by the halogen heater 116 (heating source) and held at the left and right ends by the flange 114 (holding member). The fixing member is pressed by the pressure roller 102 (pressure member). As a result, the nip forming member 106 and the pressure roller, which are located inside the fixing belt 104 (inside the fixing member) and opposed to the pressure roller 102 (pressure member) and supported by the stay (support member) 120, A nip portion 122 is formed between the nip portion 102 and the pressure member 102. Between the nip forming member 106 and the fixing belt 104 (fixing member), a lubricant 112 is included so that the fiber groove direction 130b (groove direction) is the same as the rotation direction of the fixing belt 104 (fixing member). A cloth-like sliding sheet 108b (sliding member) is installed. The lubricant circulating member 110a holds the lubricant 112 applied to the sliding sheet 108b (sliding member) on the upstream side of the nip portion 122, and applies the lubricant 112 to the fixing belt 104 (fixing member). To the downstream side of the nip portion 122. Thus, since the lubricant 112, the fiber groove direction 130b (groove direction) is supplied along the molded sliding sheet 108b (sliding member) to match the feed direction _{S 1,} the lubricant 112 Can be prevented from flowing out from the lateral end position P of the sliding sheet 108b (sliding member). Further, the fixing belt 104 (fixing member) that has circulated while the lubricant 112 is attached contacts the lubricant circulation member 110a again, thereby collecting the lubricant 112 in the lubricant circulation member 110a and fixing the lubricant 112. The belt 104 (fixing member) can be reapplied. Thereby, the slidability of the fixing belt 104 (fixing member) is improved, so that the life of the fixing device 100 can be extended.

  Further, in the fixing device 100 according to the first embodiment of the present invention, the lubricant circulating member 110a is a heat resistant fiber body made of PFA or PTFE which is a fluorinated resin. Therefore, even when the fixing belt 104 (fixing member) heated by the halogen heater 116 (heating source) slides on the lubricant circulating member 110a for a long period of time, the fixing belt 104 (fixing member) Slidability can be maintained.

  Further, in the fixing device 100 according to the first embodiment of the present invention, since the lubricant circulating member 110a is formed of a twilled fiber body, the strength and wear resistance of the lubricant circulating member 110a can be improved. . Further, the fiber groove direction 140a, 140b (groove direction) is symmetrical with respect to the center line in the longitudinal direction of the nip portion 122, and the fiber groove direction 140a, 140b is directed from the upstream side to the downstream side of the nip portion 122. The (groove direction) is directed to the center line side in the longitudinal direction of the nip portion 122. Accordingly, the lubricant that permeates along the fiber groove direction 140a, 140b (groove direction) of the lubricant circulation member 110a and is applied to the fixing belt 104 (fixing member) is the center line of the fixing belt 104 (fixing member). Are applied symmetrically with respect to the center line. Therefore, leakage of the lubricant from the left and right ends of the fixing belt 104 (fixing member) can be prevented. Further, when the lubricant applied to the fixing belt 104 (fixing member) penetrates into the sliding sheet 108b (sliding member), the left and right ends of the sliding sheet 108b (sliding member) (FIG. 5A). Can be prevented from leaking out from the lateral end position P).

  In addition, the fixing device 100 according to the first embodiment of the present invention includes a sliding sheet 108c (sliding member) in which the lubricant circulating member 110b and the sliding sheet 108a (sliding member) are integrated. Yes. Therefore, since the structure is simplified by integrating the members, the assembling property of the fixing device 100b is improved. Further, since the lubricant 112 impregnated in the sliding sheet 108c (sliding member) gradually permeates the fixing belt 104 (fixing member), the holding amount of the lubricant 112 can be increased.

  In the fixing device 100 according to the second embodiment of the present invention, the lubricant circulating member 110d is brought into contact with the fixing belt 104 (fixing member) with a lower pressure than the sliding sheet 108d (sliding member). Then, the sliding sheet 108d (sliding member) is extended by the frictional resistance accompanying wear of the lubricant circulating member 110d, and the lubricant flows out to the fixing belt 104 (fixing member) in contact with the lubricant circulating member 110d. . Therefore, since the lubricant circulating member 110d is less likely to be worn, the lubricant can be collected and applied stably over a long period of time.

  Further, the color printer 1 (image forming apparatus) including the fixing devices 100 and 100b according to the first embodiment of the present invention or the fixing device 100c according to the second embodiment has a sliding property of the fixing belt 104 (sliding member). It was set as the structure which can be hold | maintained over a long period of time. Therefore, the slidability of the fixing belt 104 (fixing member) can be maintained over a long period of time, and the life of the fixing device can be increased.

  As mentioned above, although the Example of this invention was described using drawing, this Example is only an illustration of this invention. Therefore, the present invention is not limited to the configuration of this embodiment, and it is a matter of course that changes in design and the like within the scope not departing from the gist of the present invention are included in the present invention.

100 fixing device 102 pressure roller (pressure member)
102a Core metal 102b Elastic rubber layer 104 Fixing belt (fixing member)
106 Nip forming member 108a Sliding sheet (sliding member)
110b Lubricant circulating member 112 Lubricant 114 Flange (holding member)
116 Halogen heater (heating source)
118 Reflective member 120 Stay (support member)
122 Nip portion R ₁ , R ₂ Rotating direction S1 Paper passing direction S Paper

JP 2007-334205 A

Claims (6)

A rotatable fixing member comprising an endless belt;
A heating source for heating the fixing member;
A pressure member that forms a nip portion by pressing the fixing member;
A nip forming member that forms a nip opposite to the pressure member inside the fixing member;
A cloth-like sliding member that is placed between the nip forming member and the fixing member and contains a lubricant, and is formed so that a groove direction caused by fiber weaving is the same as the rotation direction of the fixing member. When,
A support member for supporting the nip forming member;
A holding member for holding both left and right ends of the fixing member;
A lubricant circulating member that holds the lubricant on the upstream side of the nip of the sliding member and supplies the lubricant to the downstream side of the nip by adhering the lubricant to the fixing member. A fixing device.   The fixing device according to claim 1, wherein the lubricant circulating member is a heat resistant fiber body made of PFA or PTFE which is a fluorinated resin.   The lubricant circulating member is composed of a twill fiber body, and a groove direction generated by the twill weave is symmetrical with respect to a center line in the longitudinal direction of the nip, and further, from the upstream side of the nip to the downstream side of the nip. The fixing device according to claim 1, wherein the groove direction is directed toward a center line side in a longitudinal direction of the nip toward the side.   The fixing device according to claim 1, wherein the lubricant circulating member is integrated with the sliding member.   The lubricant circulating member is brought into contact with the fixing member with a lower pressing force than the sliding member, and the lubricant circulating member is extended by frictional resistance accompanying wear of the lubricant circulating member, from the lubricant circulating member, The fixing device according to claim 1, wherein the fixing member causes a lubricant to flow out to a surface in contact with the sliding member.   An image forming apparatus comprising the fixing device according to claim 1.