JP2010230711A - Fixing device and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device etc. that certainly prevents oil from oozing from a gap between ends of an endless belt and a belt holder. <P>SOLUTION: The fixing device 4 includes: a rotating body 51 having an outer peripheral surface which a fixing object contacts; an endless belt 61 which rotates while contacting the outer peripheral surface portion along a rotary shaft direction A of the rotating body; a pair of belt holders 82 having holding surfaces which rotatably hold both ends of the endless belt while contacting an inner peripheral surface thereof; a pressing body 62 forming a press-contact section which allows the fixing object to pass between the endless belt and the rotating body by pressing the endless belt from the inner surface side thereof to the outer peripheral surface portion of the rotating body; a supplying member 68 supplying oil to the inner surface portion of the endless belt, which is inside of the pair of belt holders. Streak-like grooves 10 are formed on the holding surface 83a of the belt holder, which groove becomes deeper as it proceeds to the inside while reaching an inside end in the rotary shaft direction along the rotary shaft direction A of the endless belt. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fixing device and an image forming apparatus using the same.

  In an image forming apparatus such as a printer, a copying machine, or a facsimile, an unfixed image formed by developing with a developer is transferred to a recording medium such as paper, and the transferred unfixed image is heated and fixed by a fixing device. By pressing and fixing on the recording medium, images such as characters, figures, patterns, and photographic images are formed. As a fixing device used in this image forming apparatus, there is one configured as follows.

  The fixing device includes a heating rotator in the form of a roll, an endless belt that rotates in contact with an outer peripheral surface portion along the rotation axis direction of the heating rotator, and both end portions of the endless belt as inner peripheral surface portions. A pair of belt holders having a holding surface that is rotatably held in contact with each other; and a pressing body that presses an endless belt against the outer peripheral surface portion of the heating rotating body from the inner peripheral surface side thereof; And a supply member that supplies oil such as a lubricant to the inner peripheral surface portion of the endless belt that is the inner side of the pair of belt supports.

  In this type of fixing device, a recording medium on which an unfixed image is transferred is introduced and passed through a press-contact portion formed between an endless belt pressed by a pressing body and a heating rotator. Thus, the unfixed image is heated and pressed to be fixed on the recording medium. However, in this fixing device, oil may leak from the gap between the end of the endless belt and the belt support.

  As a fixing device that takes measures to prevent such oil leakage, as an oil leakage preventing means for preventing oil leakage on the outer peripheral surfaces of a pair of belt guide members that rotatably support both ends of an endless belt. A fixing device is known that has an opening toward the inner side in the rotation axis direction of an endless belt connected to the edge portion and a groove that is inclined toward the inner side of the endless belt (Patent Document). 1).

Japanese Patent No. 4075329

  The present invention provides a fixing device that can reliably prevent oil from seeping out from the gap between the end of the endless belt and the belt holder, and a recording medium resulting from the oil seeping out in the fixing device. It is an object of the present invention to provide an image forming apparatus capable of preventing the occurrence of problems such as contamination of the apparatus and dirt in the apparatus.

The fixing device according to the present invention (A1) includes a rotating body having an outer peripheral surface with which an object to be fixed contacts, an endless belt rotating in contact with an outer peripheral surface portion along the rotation axis direction of the rotating body, and the endless belt. A pair of belt holders having a holding surface that rotatably holds both end portions in contact with the inner peripheral surface portion, and the endless belt is pressed against the outer peripheral surface portion of the rotating body from the inner peripheral surface side. Then, oil is supplied to a pressing body that forms a pressure contact portion that allows a fixing object to pass between the endless belt and the rotating body, and an inner peripheral surface portion that is inside the pair of belt supports of the endless belt. A supply member,
On the holding surface of the belt holder, a streak-like groove that reaches the inner end in the rotation axis direction along the rotation axis direction of the endless belt and becomes deeper toward the inner side is formed. It is a feature.

  The fixing device according to the present invention (A2) is the fixing device according to the above-mentioned invention A1, wherein the cross-sectional shape of the streak-shaped groove that crosses the endless belt in the rotational direction is V-shaped.

  The fixing device according to the present invention (A3) is the fixing device according to the aforementioned invention A1, wherein a plurality of the stripe-like grooves are formed at intervals in the rotation direction of the endless belt.

  The fixing device according to the present invention (A4) is the fixing device according to the aforementioned invention A1, wherein at least the surface of the streak-like groove is formed of a material having a high affinity with the oil.

  The fixing device according to the invention (A5) is the fixing device according to the invention A1 or A3, wherein the fixing device has a volume larger than that of the streak-like grooves at different positions on the holding surface of the belt holder in the rotational direction of the endless belt. A second groove is formed.

  The fixing device according to the invention (A6) is the fixing device according to the invention A5, wherein the second groove is formed at least at a position facing an end portion of the supply member in the rotation axis direction of the endless belt. It is.

The image forming apparatus according to the present invention (B) includes an image forming apparatus that forms an unfixed image and transfers the image to a recording medium, and a fixing apparatus that fixes the unfixed image transferred by the image forming apparatus to the recording medium. Have
The fixing device is the fixing device according to any one of the first to sixth aspects.

  According to the fixing device of the invention A1, it is possible to reliably prevent oil from seeping out from the gap between the end of the endless belt and the belt holder.

  In the fixing device of the invention A2, oil seepage is more reliably prevented as compared with the case where the configuration of the invention is not provided.

  In the fixing device of the invention A3, oil seepage can be prevented more reliably than in the case where the fixing device of the invention is not provided.

  In the fixing device of the invention A4, oil seepage can be prevented more reliably than in the case where the fixing device of the invention is not provided.

  In the fixing device according to the invention A5, oil exudation that collects when the rotation of the endless belt is stopped is suppressed as compared with the case where the fixing device according to the invention is not provided.

  In the fixing device of the invention A6, the effect of the invention A5 can be obtained more reliably than in the case of not having the configuration of the invention.

  According to the image forming apparatus of the invention B, problems such as dirt on the recording medium and dirt in the apparatus due to oil seepage from the gap between the end of the endless belt and the belt support in the fixing device occur. Can be prevented.

1 is a schematic explanatory diagram illustrating a main part of an image forming apparatus using a fixing device according to an embodiment. FIG. 2 is a perspective view showing a main part of the fixing device of FIG. 1. FIG. 3 is an explanatory diagram showing a state when viewed from one end of the fixing device of FIG. 2. FIG. 3 is an exploded perspective view of a pressure rotator in the fixing device of FIG. 2. It is a partial cross section figure which shows a state when a pressurization rotary body is press-contacted to a heating roll. It is a perspective view which shows the belt end part holding body which formed the stripe-shaped groove | channel. It is the front view seen from the inner side of the belt rotating shaft direction of the belt edge part holding body of FIG. 6, and its sectional drawing. It is explanatory drawing which shows the cross-sectional shape of a stripe-shaped groove | channel. It is a partial cross section figure which shows a state when the pressurization rotary body equipped with the belt edge part holding body of FIG. 6 is made to press-contact with a heating roll. It is sectional drawing which follows the Q1-Q1 line | wire of FIG. It is a graph which shows the result of the evaluation test regarding oil oozing-out. It is a perspective view which shows the belt end part holding body at the time of forming a large sized groove | channel in addition to a stripe-shaped groove | channel. It is a partial cross section figure which shows a state when the pressurization rotary body equipped with the belt edge part holding body of FIG. 12 is made to press-contact with a heating roll. It is sectional drawing which follows the Q1-Q1 line | wire of FIG.

  Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as “embodiments”) will be described with reference to the drawings.

  FIG. 1 shows an image forming apparatus using a fixing device according to an embodiment.

  An image forming apparatus 1 forms an unfixed toner image based on image information in a housing (not shown) and finally transfers the toner image to a recording medium 9 such as paper. A paper feeding device 3 that accommodates the recording medium 9 and is conveyed and supplied to the image forming device 2 and a fixing device 4 that fixes the toner image transferred by the image forming device 2 to the recording medium 9 are mainly equipped. ing. A one-dot chain line with an arrow in FIG. 1 indicates a main conveyance path of the recording medium 9.

  The image forming apparatus 2 can form and transfer a toner image using a known electrophotographic method, for example. Specifically, a photosensitive drum 12 that rotates in the direction of the arrow is provided. A charging device 13 that charges the surface (image holding surface) of the photosensitive drum 12 around the photosensitive drum 12 and the photosensitive drum 12 are charged. An exposure device 14 that irradiates light on the surface based on image information (signal) to form an electrostatic latent image having a potential difference, and the electrostatic latent image on the photosensitive drum 12 is developed with toner as a developer. The developing device 15 for forming an image, the transfer device 16 for transferring the toner image to the recording medium 9 supplied from the paper feeding device 3, and the toner remaining on the surface of the photosensitive drum 12 after the transfer are removed and cleaned. A cleaning device 17 is mainly arranged.

  For example, as the photosensitive drum 12, an image holding surface having a photosensitive layer (photoconductive layer) made of an organic photosensitive material is formed on the peripheral surface of a grounded cylindrical substrate. As the charging device 13, a contact charging type device is used in which charging is performed by applying a charging voltage to a charging roll rotating in contact with the surface of the photosensitive drum 12. As the exposure device 14, an LED (light emitting diode) type recording head, a semiconductor laser scanning device, or the like is used. In the exposure device 14, image information input from an image reading device or storage medium reading device equipped or connected to the image forming apparatus 1 (including wireless communication), or an external device serving as an image creation source such as a computer is illustrated. After the required processing is performed by the image processing apparatus that does not, an image signal obtained by the processing is input.

  As the developing device 15, the surface of the photosensitive drum 12 is passed through a developing roll 15 a to which a developing voltage is applied in a state where a developer (a one-component developer, a two-component developer, etc.) containing toner of a predetermined color is charged. What is supplied to is used. As the transfer device 16, a contact type device is used in which transfer is performed by applying a transfer voltage to a transfer roll rotating in contact with the surface of the photosensitive drum 12.

  The sheet feeding device 3 includes a storage cassette 31 that stores a plurality of recording media 9 of a predetermined size and type to be supplied to the image forming device 2 and a recording medium 9 stored in the storage cassette 31. It mainly includes a delivery device 32 that feeds and conveys one sheet at a time. A plurality of storage cassettes 31 are provided as necessary. The recording medium 9 is not particularly limited, but a sheet-like recording medium such as paper, cardboard, a transparent sheet, or a postcard is mainly used.

  The sheet feeding device 3 also includes a plurality of conveyance roll pairs 33, 34,... For conveying the recording medium 9 from the storage cassette 31 to the transfer section of the image forming device 2 (between the photosensitive drum 12 and the transfer device 16). And a paper conveyance path for paper feeding composed of a conveyance guide material or the like. The pair of paper transport rolls 34 is configured as a transport timing adjustment roll pair that is driven and sent out when a predetermined feed timing comes after temporarily stopping the leading end portion of the transported recording medium 9. . The sheet conveyance path is also installed between the image forming device 2 and the fixing device 4.

  The fixing device 4 includes a roll-shaped heating rotator 5 that is heated inside the housing 41 so that the surface temperature is maintained at a predetermined temperature by a heating unit, and rotates in the direction of the arrow. A belt-shaped pressure rotator 6 that rotates while forming a pressure contact portion (fixing processing portion) NP by contacting a surface portion substantially along the rotation axis direction with a predetermined pressure is installed. Reference numeral 39 in FIG. 1 denotes a pair of discharge rolls for discharging the recording medium 9 after fixing from the fixing device 4. Details of the fixing device 4 will be described later.

  Basic image formation by the image forming apparatus 1 is performed as follows.

  First, in the image forming apparatus 2, the photosensitive drum 12 starts to rotate, the surface of the rotating photosensitive drum 12 is charged to a required charging potential by the charging device 13, and then the charged surface of the photosensitive drum 12 is exposed. The device 14 is irradiated with light based on the image signal to form an electrostatic latent image having a required latent image potential. Subsequently, when the electrostatic latent image moves with the rotation of the photosensitive drum 12 and passes through the developing device 15, the charged toner supplied from the developing roll 15 a of the developing device 15 is statically transferred to the latent image portion. The toner image is developed by being attached electrically. Thereafter, the toner image on the photosensitive drum 12 is electrostatically transferred to the recording medium 9 sent out from the paper feeding device 3 and conveyed at a transfer position facing the transfer device 16. The surface of the photosensitive drum 12 after the transfer of the toner image is cleaned by the cleaning device 17.

  Next, the recording medium 9 on which an unfixed toner image is formed in the image forming device 2 is conveyed to the fixing device 4 and is introduced into the pressure contact portion NP between the heating rotator 5 and the pressure rotator 6. As a result, in the fixing device 4, the recording medium 9 is conveyed and passed while being sandwiched between the press contact portions NP. At that time, an unfixed toner image is heated and pressurized and fixed to the recording medium 9. The recording medium 9 after being fixed is discharged from the fixing device 4 and then conveyed by a discharge roll pair 39 or the like and sent to a discharge storage portion (not shown).

  Next, details of the fixing device 4 will be described.

  As shown in FIGS. 2 to 3, the fixing device 4 presses the pressing rotator 6 against the heating rotator 5 in addition to the roll-shaped heating rotator 5 and the belt-shaped pressing rotator 6. A mechanism 7 is provided. In FIG. 2, illustration of a part of the components of the pressure rotator 6 (such as a belt inner surface holding component) is omitted.

  The roll-shaped heating rotator 5 is mainly composed of a heating roll 51, a heating source 52 that heats the heating roll 51, and a heating support frame 53 that rotatably supports the heating roll 51 at both ends thereof. .

  The heating roll 51 is obtained by forming an elastic layer and a release layer in this order on the surface of a metal cylindrical base material having a length larger than the maximum conveyance width of the recording medium 9 to be fixed. is there. Both ends of the heating roll 51 are rotatably supported by a heating support frame 53 via bearing-type bearings 54, and the main body side of the image forming apparatus 1 with respect to a gear 55 attached to one end thereof. Rotational power is transmitted from the rotational drive unit arranged at, so that it is rotationally driven in the direction indicated by the arrow. The heating source 52 is composed of, for example, two halogen lamps installed inside the cylinder of the heating roll 51 (see FIG. 3), and both ends thereof are supported by the casing 41 of the fixing device 4. The temperature of the roll surface of the heating roll 51 is detected by a temperature detector (not shown), and the heating operation of the heating source 52 is controlled based on the detection information, so that the heating roll 51 is maintained at a predetermined temperature.

  The heating support frame 53 is provided with a support shaft 56 at a portion on the introduction side of the recording medium 9 with a pressure contact portion NP formed by the heating rotator 5 and the pressure rotator 6 interposed therebetween, and the pressure contact portion NP. A spring support surface portion 57 used in combination with the pressing mechanism 7 is formed at a portion on the recording medium discharge side with respect to the recording medium. The heating support frame 53 is attached in a state where the attachment surface portion 59 and the like are fixed to the casing 41 of the fixing device 4 by screwing or the like.

  As shown in FIGS. 3, 4, and the like, the belt-shaped pressurizing rotator 6 includes an endless belt 61 that rotates in contact with the outer peripheral surface portion of the heating roll 51 along the rotation axis direction A (FIG. 2), and an endless belt. A pressing body 62 that presses the belt 61 against the outer peripheral surface portion of the heating roll 51 from the inner peripheral surface side to form a pressure contact portion NP, a belt internal holding body 81 that rotatably supports the endless belt 61, and a pair of The belt holder 80 includes belt end holders 82A and 82B, and a felt member 68 impregnated with a release agent oil that is applied to the inner peripheral surface of the endless belt 61 and supplied.

  The endless belt 61 is a cylindrical belt having a width approximately the same as the length of the heating roll 51. As the endless belt 61, a belt base material formed in a thin cylindrical shape with a synthetic resin such as polyimide and having a release layer made of a fluorine-based resin or the like is used.

  As shown in FIGS. 3, 4, and the like, the pressing body 62 includes a head portion 64 and a pad portion 65 each having an elongated shape having substantially the same length as the width of the endless belt 61.

  The head part 64 is formed of an inelastic member made of synthetic resin, metal, or the like. The head portion 64 in this embodiment is positioned on the recording medium discharge side of the press contact portion NP, and is positioned on the recording medium introduction side of the press contact portion NP and the contact portion 64a that actually presses the endless belt 61 against the outer peripheral surface of the heating roll 51. Thus, it is formed in a shape having a holding surface portion 64b for holding the pad member 65 and a flat contact surface portion 64c that the support material 66 contacts and supports. The pad portion 65 is formed of an elastic member made of a rubber material or the like. The pad portion 65 in this embodiment is fixed to the substrate 65b with silicon rubber formed in an elongated plate-like shape with the pressing surface 65a facing up. The pressing body 62 is supported by two support plates 66A and 66B described later.

  The belt inner holding body 81 in the belt holding body 80 has a substantially U-shaped cross section in which a side surface portion and a bottom surface portion for guiding the inner peripheral surface portion excluding both end portions of the endless belt 61 are mainly held rotatably. It is the synthetic resin holding material which consists of this form. The internal holding body 81 has insertion protrusions 81a formed at both ends thereof, and a plurality of guide ribs (protrusions) 81b formed at the side surface of the guide. Further, a mounting surface portion 81c for attaching the felt member 68 impregnated with a predetermined amount of the above-mentioned release agent oil is formed on a part of the guide side surface portion of the belt inner holding body 81. As the release agent oil, for example, silicone oil, fluorine oil or the like having a required viscosity is used. The filter member 68 is attached to the attachment surface portion 81c of the internal holder 81 by a fixing means such as adhesion.

  The pair of belt end holding members 82A and 82B in the belt holding member 80 is a synthetic resin holding material on which disk-shaped guide portions 83 for holding the inner peripheral surfaces of both end portions of the endless belt 61 in a rotatable manner are formed. It is. The guide portion 83 is positioned substantially at the center thereof, and has a cylindrical circumferential surface holding surface portion 83a in which the inner peripheral surface of the endless belt 61 is held in contact with the guide portion 83, and an endless belt positioned outside the holding surface portion 83a. A large-diameter portion (flange portion) 83b having a diameter larger than that of the holding surface portion 83a that prevents the end portion 61 from being displaced is positioned on the opposite side of the large-diameter portion 83b of the holding surface portion 83a and is located inside the endless belt 61. It is comprised by the inclined surface part (taper surface part) 83c which inclines so that it may become a small diameter as it goes. A part of the holding surface portion 83a is formed as a substantially flat plane portion 83d in order to secure a region where the endless belt 61 is in contact with the heating roll 51 and elastically deforms to form the press contact portion NP.

  The end holder 82 has an attachment hole 84 into which the insertion protrusion 81a of the belt internal holder 81 is fitted on the inner surface of the guide portion 83, and the other portion of the inner surface of the guide portion 83. A support hole 85 for inserting and supporting the end portions 66c of the support plates 66A and 66B is formed. A mounting portion 86 for inserting and positioning the end portion of the head member 64 of the pressing body 62 is formed inside the flat portion 83 d of the guide portion 83. In addition, the end holding body 82 is formed with an attaching portion 87 on the outer surface side of the guide portion 83, which is used when attaching to a component (pressure swing support frame) of the pressing mechanism 7.

  The belt holding body 80 is assembled by fitting and inserting the insertion protrusions 81a of the belt inner surface holding body 81 into the mounting holes 84 of the pair of belt end holding bodies 82, respectively. The pressing body 62 is positioned on the belt internal holding body 81 by attaching both end portions of the head member 64 having the pad member 65 installed on the holding surface portion 64 to the mounting portions 86 of the belt end holding body 82. It is installed in the state to do. In FIG. 4 and the like, reference numeral 69 denotes a friction reducing sheet that reduces the frictional resistance between the pressing body 62 and the endless belt 61. The friction reducing sheet 69 is attached with its one end 69 a sandwiched between the pressing body 62 and the belt holding body 80, and its free end 69 b is interposed between the pressing body 62 and the endless belt 61. Attached to the state.

  As shown in FIGS. 2 to 4, the support plates 66 </ b> A and 66 </ b> B that support the pressing body 62 are arranged almost parallel to each other, and the upper long side portion 66 a is pressed against the pressing body 62 (the head member of the pressing body 62). 64 in contact with the contact surface portion 64c) of the heating rotary roll 51 along the rotational axis direction A. Further, as described above, the support plates 66A and 66B themselves are held by the belt holder 80 by fitting both end portions 66c thereof into the support holes 85 of the belt end holder 82.

  The pressing mechanism 7 supports a pair of pressure swing support frames 71 that swing while supporting both ends of the pressure rotary body 6, and swings each pressure swing support frame 71 in a direction approaching the heating rotary body 5. The compression coil spring 73 is pressed so as to be moved.

  As shown in FIG. 3 and the like, the pressure swing support frame 71 is formed in a substantially V-shape as a whole, and one end portion 71 a on its fulcrum side is supported by the heat support frame 53. It is rotatably attached via a shaft 56 and swings in the directions of arrows C and D with the support shaft 56 as a fulcrum. The swing support frame 71 supports the pressure rotator 6 by fitting a mounting portion 86 of the belt end holding body 82 of the belt holding body 63 into a mounting portion formed at a substantially central bent portion. To do.

  Further, the pressure swing support frame 71 supports the pressure rotating body 6 and is maintained in a state of swinging in a direction (arrow C direction) approaching the heating rotating body 5 (heating roll 51). The pressure rotator 6 is brought into contact with the surface of the heating rotator 5. Further, the swinging support frame 71 is formed with a spring pressing surface portion 72 that is pressed against the other end portion 71b on the displacement side by the force of the compression coil spring 73. The spring pressing surface portion 72 is formed in a state where it can be opposed to the spring supporting surface portion 57 of the heating support frame 53 with a gap.

  The compression coil spring 73 is a moving end of the pressure swing support frame 71 by a spring mounting column 77 having spring stopper projections 77a and screw portions 77b formed on the upper and lower portions of the column body longer than the free length of the coil spring. It is attached to the part side. That is, the lower part of the support column 77 that is inserted into the winding space of the compression coil spring 73 and protrudes from one end of the coil spring is connected to the heating support frame 53 side from the through hole formed in the spring pressing surface portion 72 of the swing support frame 71. After that, the threaded portion 77b of the projecting column is fitted into a screw hole formed in the spring support surface portion 57 of the heating support frame 53, and then the column 77 is fixed by tightening with a nut 77d. Further, the compression coil spring 73 is sandwiched between the spring stop projection 77a of the support column 77 and the spring pressing surface portion 72 and is held in a compressed state by a predetermined amount. Thereby, the spring force (F: FIG. 3) which pushes the spring pressing surface part 72 in the direction which approaches the spring support surface part 57 is exhibited.

  According to the pressing mechanism 7, the spring pressing surface portion 72 is pressed by the spring force (F) of the compression coil spring 73, and the pressure swing support frame 71 swings in the direction approaching the heating roll 51 (arrow C direction). Kept in a state. As a result, the pressure rotator 6 supported by the swing support frame 71 is kept in contact with the surface of the heating roll 51 at a predetermined pressure.

  Specifically, the force (pressing force) G finally generated (in the lever principle) in the pressure swing support frame 71 swinging in the direction of arrow C by the spring force of the compression coil spring 73 is the pressure rotating body 6. The pair of belt end holding bodies 82A and 82A is finally transmitted to the pressing body 62 via the two support plates 66A and 66B. As a result, the pressing body 62 is pressed against the surface of the heating roll 51 with a predetermined pressure via the endless belt 61.

  The two support plates 66A and 66B support the pressing body 62 (the head portion 64) in a state in which the pressing body 62 is in direct contact with the contact surface portion 64c opposite to the pressing surface portion. The support plates 66 </ b> A and 66 </ b> B receive the pressing force G generated by the pressing mechanism 7 and press the pressing body 62 toward the heating roll 51. By installing the two support plates 66 under the head portion 64, the pressing force G of the pressing mechanism 7 received by the support plate 66 is directly and efficiently transmitted to the head portion 64 of the pressing body 62. As a result, the pressure distribution in the direction of the rotation axis of the press contact part NP becomes more stable.

  In the fixing device 4, as shown in FIGS. 3 and 5, the pressing body 62 presses the endless belt 61 against the heating roll 51, so that the heating roll 51 and the endless belt 61 (pressing body 62) A fixing press contact portion NP is formed in which the endless belt 61 is in contact with the outer peripheral surface of the heating roll 51 with a required width (length in the rotation direction). At this time, the press contact portion NP is formed in a state where both the head portion 64 and the pad portion 65 of the pressing body 62 are in contact with the outer peripheral surface of the heating roll 51 via the endless belt 51.

  Further, when the heating roll 51 rotates, the endless belt 61 follows the rotation and rotates in the direction indicated by the arrow. When the endless belt 61 rotates, the release agent oil is applied to the inner peripheral surface of the endless belt 61 by a small amount from the felt member 63 and supplied as shown in FIG. Thereby, the friction between the endless belt 61 and the pressing body 62 (strictly speaking, the friction reducing sheet 69) is reduced, and the endless belt 61 smoothly rotates.

  Fixing at the press contact portion NP is performed as follows.

  That is, when the recording medium 9 that holds an unfixed toner image, which is a fixing target, is introduced into the press contact portion NP, first, the pad portion 65 disposed on the recording medium introduction side of the press contact portion NP (the endless belt 61). The recording medium 9 is pressed against the heating roll 51 that is heated and rotated. Subsequently, the head portion 64 (the contact portion 64a) disposed on the recording medium discharge side of the press contact portion NP presses the recording medium 9 against the heating roll 51 (via the endless belt 61). Then, the recording medium 9 that holds the unfixed toner image has an outer peripheral surface of the heating roll 51 of the heating rotator 5 by the pad portion 65 and the head portion 64 of the pressing body 62 of the pressing rotator 6 at the press contact portion NP. It is heated in a state where it is pressed against and is conveyed so as to pass through the press contact part NP by the rotation of the heating roll 51. By passing through the pressure contact portion NP in this way, the unfixed toner image is heated and pressurized and fixed to the recording medium 9.

  Further, in the fixing device 4, the following measures for preventing the release agent oil from exuding from between the end portion of the endless belt 61 and the guide surface portion 83 of the pair of belt end holding members 82A and 8B. Is given.

  That is, a plurality of streak-like grooves 10 are formed in each guide portion 83 of the pair of belt end holders 82A and 8B as shown in FIGS. The plurality of grooves 10 are formed at substantially the same interval with respect to the rotation direction (circumferential direction) of the endless belt 61 in the region excluding the flat surface portion 83d of the holding surface portion 83a.

  Further, as shown in FIG. 7, each of the streak-like grooves 10 reaches from the holding surface portion 83a along the rotational axis direction A of the endless belt 61 to the end portion of the inclined surface portion 83c located on the inner side thereof, The groove depth d is formed so as to increase inward in the rotation axis direction A. The groove 10 in this embodiment is a groove portion formed with the same groove depth d1 in the range from the position of the holding surface portion 83a away from the large diameter portion 83b of the guide portion 83 to the intermediate position inside the rotation axis direction A. 10a and a gradually increasing depth d2 (holding surface portion 83a) that gradually inclines and deepens from the holding surface portion 83a at a certain angle in a range from an intermediate position of the holding surface portion 83 to a position reaching the inner end of the inclined surface portion 83c. The groove portion 10b is formed with a dimension of the depth portion farthest from the groove 10b.

  Further, as shown in FIG. 8, the groove 10 is formed such that the cross-sectional shape of the endless belt 61 crossing in the rotation direction is a V shape (in other words, a wedge shape or a pointed shape). . For this reason, all the groove depths d indicate the distance from the holding surface portion 83a to the bottom end portion in the V-shaped cross section. The groove 10 exhibits a function of drawing oil into the groove by a principle such as a capillary phenomenon as the release agent oil applied by the felt member 68 moves to both ends of the endless belt 61. From this point of view, the width w of the groove 10 in the rotational direction of the endless belt 61 needs to be adjusted depending on the supply amount of the release agent oil, viscosity (viscosity) and the like. A relatively narrow width of 0.0 mm is sufficient.

  9 and 10 show the state of the fixing device 4 when the belt end holding body 82 (for convenience, one holding body 82A is shown) in which the streak-like grooves 10 are formed is mounted. In FIG. 9, the endless belt 61 is not shown. 10 is a cross-sectional view taken along line Q1-Q1 of FIG.

  In the fixing device 4, as described above, the endless belt 61 rotates following the rotation of the heating roll 51 during the fixing operation, and at the time of the rotation, the release agent oil is fed from the filter member 68 to the inner peripheral surface of the endless belt 61. Is applied, but after a part of the oil is transferred to the inner peripheral surface portions of both end portions of the endless belt 61 and moves, the gap with the guide portion 83 (strictly, the holding surface portion 83a) of the belt end holding body 82 is applied. It tries to bleed out through.

  However, the release agent oil that moves toward both ends of the endless belt 61 is transported so as to move in the rotational direction as the endless belt 61 rotates, and at the time of the rotation, the belt end holding body. It passes through the plurality of streak-like grooves 10 in the guide portion 83 of 82.

  For this reason, in each streak-like groove 10, the oil existing on the inner peripheral surface of the endless belt passing across the groove is trapped into the groove and the introduced oil is introduced into the groove depth d. Move to the deeper side. Finally, the moved oil is discharged from the inner end of the groove 10 and returned to the inner space of the endless belt 61 between the belt end holders 82A and 82B.

  As a result, the release agent oil that moves toward both end portions of the endless belt 61 is prevented from seeping out from the belt end portion through the gap with the holding surface portion 83a of the guide portion 83 of the belt end portion holding body 82. The The above-described effect of preventing oil bleeding by the streak-like grooves 10 is obtained particularly effectively at the initial stage when the endless belt 61 starts to rotate.

  FIG. 11 shows the result of an evaluation test in which the presence or absence of oil oozing out from the gap between the end of the endless belt 61 and the belt end holders 82A and 82B using the fixing device 4 according to this embodiment is shown. .

  The evaluation test was performed under the following conditions. First, as the belt end portion holding body 82, the holding surface portion 83a having an outer diameter of 29 mm and a width (length along the rotation axis direction A) of about 10 mm and an inclined surface portion 83c having a width of about 3 mm are shown in FIGS. As shown in FIG. 10 and the like, a total of seven streak-like grooves 10 having a V-shaped cross section were formed with substantially equal intervals in the belt rotation direction (Example). The groove 10 has a width w of 2 mm and a length to the end of the inclined surface portion 83c of about 7.8 mm (the groove 10 does not exist on the surface portion extending about 3 mm from the large diameter portion 83b of the holding surface portion 83a). The depth of the deepest portion from the surface of the holding surface portion 83 (corresponding to the depth d2 portion shown in FIG. 7b) was set to each depth shown in FIG.

The belt end holding member 82 was manufactured by injection molding including the formation of the groove 10 using polyphenylene sulfide (PPS) resin. Further, a polyimide belt having a diameter (outer diameter) of 30 mm and a thickness of 0.095 mm is used as the endless belt 61, and the pressure contact width of the endless belt 61 with respect to the heating roll 51 is 4 to 8 mm. It installed in the state which forms the press-contact part NP. Further, as a release agent oil, in a state where the viscosity using a silicone oil consisting of (30 to 60 mm ² / s at 180 ℃) 200~400mm ² / s at 25 ° C., was impregnated with the oil to the felt member 68 It set so that it might apply | coat by making it contact the inner peripheral surface of the endless belt 61. FIG. The PPS resin that forms the entire belt end holding member 82 is made of a material that can provide good slidability with the endless belt 61, and is compatible with silicone oil as a release agent oil. It is also a synthetic resin made of a material exhibiting characteristics that are not low in properties.

  Then, in the fixing device 4, the heating roll 51 is heated so that the surface temperature becomes 160 ° C., and is rotated for 1000 minutes at a rotation speed of 300 (mm / second), and then is stopped for 5 minutes. Was repeated 6 times. During this test operation, the endless belt 61 also rotates and stops with the same contents as the heating roll 51. After this test operation was completed, the state of the end portion of the endless belt 61 was observed and evaluated based on the level standard shown in FIG.

  For comparison, a helical groove extending as a belt end holder 82 on the holding surface portion 83 of the guide portion gradually inwardly in the rotational axis direction A in the rotational direction of the endless belt 61 (the above-mentioned patent). A fixing device having the same configuration was prepared except that a groove (as shown in FIG. 11b of Reference 1) formed (comparative example) was mounted, and the above-described evaluation test was performed in the same manner. The spiral groove in the comparative example has a shape as shown in FIG. 11b in the gazette of Patent Document 1, and the depth d is the same dimension (1 mm) in the entire region (the width is the same as the embodiment). Is).

[Other embodiments]
12 to 14 show a belt end holding member and a part of a fixing device according to another embodiment.

  The belt end holder 82 in this embodiment is a large groove having a large volume compared to the streak-like groove 10 in a portion different from the streak-like groove 10 with respect to the holding surface part 83 and the inclined surface part 83c of the guide part. 15 is formed. The large groove 15 is a groove having the same depth d in the belt rotation direction A, and is, for example, the same as the maximum depth d2 of the streak-like groove 10. And the large sized groove | channel 15 in this embodiment is comprised as a groove | channel whose volume is about 1.5-10 times large by setting the width | variety to the dimension of 1.5-10 times the width | variety of the stripe-like groove | channel 10. ing.

  Further, the large groove 15 is installed so that the felt member 68 impregnated with the release agent oil exists at a position below the gravity direction in the fixing device 4, and as shown in FIGS. 13 and 14, The filter member 68 is formed at the position of the guide portion 83 facing the end portion 68 a in the belt rotation direction A.

  In the fixing device 4 using the belt end holding member 82 formed by combining the large groove 15 with the streak-like groove 10, particularly when the heating roll 51 and the endless belt 61 are stopped, the inner peripheral surface of the endless belt 61. The release agent oil adhering to the belt gradually collects by gravity so as to gather at the lowermost part of the inner peripheral surface of the belt, and the oil in the accumulated oil that is not reabsorbed by the felt member 68 is collected at both ends of the endless belt 61. The outer end of the belt end holder 82 and the guide portion 83 of the belt 82 so that it leaks to the outside, but is captured in the groove of the large groove 15 and is prevented from leaking to the outside from the belt end. The Further, since the large groove 15 is formed at a position (substantially right side) facing the end 83a of the felt member 83, the effect of preventing oil leakage by the large groove 15 is that the endless belt 61 continues for a long time. Can be obtained effectively when rotating.

  For example, when the felt member 68 impregnated with the release agent oil is not arranged at the lowest position in the direction of gravity, the large groove 15 is a guide facing the end portion 68a of the felt member 68 arranged at the other position. In addition to forming the portion 83, at least one portion may be formed on the lowermost portion of the guide portion 83 in the gravity direction. In this case, the large groove 15 formed at the lowermost position prevents the release agent oil that collects at the lower part of the inner peripheral surface of the belt when the endless belt 61 stops rotating from leaking out from the belt end. Is done.

  In the above-described embodiment, the case where a plurality of the streak-like grooves 10 are formed is illustrated. However, when there is little oil seepage, etc., only one streak-like groove 10 may be formed. Absent.

  Further, with regard to the depth d of the streak-like groove 10, the release agent oil introduced into the groove is finally flowed toward the inner side of the belt end holding member 82 (inner side in the rotation axis direction of the endless belt). For example, even if the groove is continuously deepened as it goes inside the rotation axis direction A in the entire groove, or stepwise (intermittently) It may be deeper.

  In the above embodiment, the belt end holding member 82 including the streak-like grooves 10 is illustrated as being formed of a synthetic resin having a high affinity with the release agent oil. Only the surface portion of the streak-like groove 10 may be formed of a material having a high affinity with the release agent oil. In this case, it can be realized, for example, by applying a material having high affinity to the surface of the streak-like groove 10. Moreover, you may form only the surface of the holding surface 83a of the guide part which forms the stripe-shaped groove | channel 10 with the material with high affinity (including the whole surface of the groove | channel 10).

  In addition, as the image forming apparatus 2 in the image forming apparatus 1, a multicolor image forming type image forming apparatus that can form toner images of a plurality of colors and transfer them to the recording medium 9 may be applied. As a transfer method in the image forming apparatus 2, a known intermediate transfer method using an intermediate transfer member may be employed.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 2 ... Image forming apparatus 4 ... Fixing apparatus 5 ... Heating rotary body 9 ... Recording medium (a part of fixing object)
10 ... Striped groove 15 ... Large groove (second groove)
51 ... Heating roll (rotating body)
61 ... Endless belt 62 ... Pushing body 68 ... Felt member (supply member)
68a ... end portions 82A, 82B ... a pair of belt end holding bodies (a pair of belt holding bodies)
83a ... Holding surface portion (holding surface)
83c ... inclined surface (inner end)
A ... Rotational axis direction NP ... Press contact part

Claims (7)

A rotating body having an outer peripheral surface with which an object to be fixed contacts;
An endless belt that rotates in contact with an outer peripheral surface portion along a rotation axis direction of the rotating body;
A pair of belt holders having a holding surface that rotatably holds both end portions of the endless belt in contact with the inner peripheral surface portion thereof;
A pressing body that presses the endless belt from the inner peripheral surface thereof to the outer peripheral surface portion of the rotating body to form a pressure contact portion that allows a fixing object to pass between the endless belt and the rotating body;
A supply member that supplies oil to the inner peripheral surface portion that is the inside of the pair of belt supports of the endless belt,
On the holding surface of the belt holder, a streak-like groove that reaches the inner end in the rotation axis direction along the rotation axis direction of the endless belt and becomes deeper toward the inner side is formed. A fixing device characterized.   The fixing device according to claim 1, wherein the streak-like groove has a V-shaped cross section that crosses the endless belt in the rotation direction.   The fixing device according to claim 1, wherein a plurality of the streaky grooves are formed at intervals in a rotation direction of the endless belt.   The fixing device according to claim 1, wherein at least a surface of the streak-like groove is formed of a material having a high affinity with the oil.   4. The fixing device according to claim 1, wherein a second groove having a volume larger than that of the streak-like groove is formed at a position where the endless belt rotates in a holding surface of the belt holder. 5.   The fixing device according to claim 5, wherein the second groove is formed at least at a position facing an end portion of the supply member in a rotation axis direction of the endless belt. An image forming device that forms an unfixed image and transfers the image to a recording medium; and a fixing device that fixes the unfixed image transferred by the image forming device to the recording medium.
An image forming apparatus, wherein the fixing device is the fixing device according to claim 1.

Images