JP2007057851A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the increase in speed of a fixing operation, prevention of abnormal sounds from a fixing film, and extension of a lifetime of the fixing film, by a simple configuration. <P>SOLUTION: A lubricant is surely prevented from overflowing from both end parts in a breadthwise direction of a fixing film 18a to eliminate image defects due to passing-around to a fixing film surface of the lubricant, by such configuration that a storing recessed part 18f for holding an excess of the lubricant is provided on a guide member 18e of the fixing film 18a and the lubricant is enclosed inside the fixing film 18a to satisfactorily hold the lubricant without leakage to the outside regardless of the increase in quantity of the lubricant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing device and an image forming apparatus configured to thermally fix an unfixed image by applying heat from a heater to a sheet-like recording material through a fixing film.

  In general, in various image forming apparatuses such as copying machines, printers, and facsimiles adopting an electrophotographic system, a sheet-like recording material to which a toner image formed in an image forming unit is transferred is conveyed to a fixing device and the sheet-like recording is performed. The unfixed toner image on the material is fixed. As one of the fixing methods, there is a film fixing method in which a fixing film having a movable belt shape is brought into contact with a heater.

  The fixing film used in this film fixing system is held so that the shape at the time of rotation is guided by the guide member, and is arranged so as to be in surface contact with the surface of the heater, A sheet-like recording material is introduced into the fixing nip where the fixing pressing unit such as a pressure roller is in pressure contact with the sheet, and the sheet is formed by the heating action from the heater and the pressing action of the fixing pressing unit. The toner on the recording material is melted to thermally fix the unfixed image.

  At this time, the fixing film slides in close contact with the surface of the heater, but in order to reduce the sliding friction resistance between the fixing film and the heater, a heat-resistant lubricant such as grease is used. It is generally performed to interpose between the two members.

  On the other hand, in recent years, the temperature adjustment temperature of the heater tends to increase year by year due to the demand for high speed fixing, and as a result, the lubricant (grease) used in the fixing film Deterioration is getting easier. As the lubricant deteriorates, naturally, the slidability between the heater and the fixing film deteriorates. For example, abnormal noise is periodically generated, and the user feels uncomfortable or sheet-like. There is also a possibility that conveyance of the recording material may be difficult. In order to solve such a problem, the amount of lubricant used for the fixing film is increasing in recent image forming apparatuses.

  However, if the amount of the lubricant is simply increased, the lubricant may overflow from both end portions in the width direction of the fixing film. In particular, when the temperature control temperature of the heater is raised, the fluidity of the lubricant is increased, so the tendency of the lubricant to wrap around the surface of the fixing film from both ends becomes strong. May adhere to the sheet-like recording material and stain the image. Further, when the lubricant overflows from both ends of the fixing film, the amount of the lubricant secured in the fixing device is reduced at an early stage, and the above-described problems are likely to occur.

  With regard to the problem related to the wraparound of the lubricant to the surface of the fixing film, for example, in the following patent document or the like, a blade means whose tip is in contact with the outer periphery of both end portions of the fixing film is provided. Proposals have been made to prevent the lubricant from wrapping around the surface of the fixing film by the scraping action. However, in such a conventional apparatus, there is a problem that the structure becomes complicated, and the lubricant that escapes from the gap between the heater and the fixing film cannot be prevented from flowing around the surface of the fixing film. In particular, when the lubricant is greatly increased as the speed of the fixing device increases, the wraparound of the lubricant tends to become remarkable.

Japanese Patent Laid-Open No. 08-305187

  SUMMARY OF THE INVENTION Accordingly, the present invention provides a fixing device and an image forming apparatus that can contain a lubricant in a fixing film with a simple configuration and can maintain the slidability of the fixing film well over a long period of time. Objective.

  In order to achieve the above object, in the fixing device according to the first aspect of the present invention, the annular fixing film guided by the guide member during movement is in close contact with the surface of the heater via a lubricant. An unfixed image on the sheet-like recording material is introduced by introducing the sheet-like recording material into a fixing nip where the fixing film and the fixing pressure unit are pressed against each other. In the fixing device configured to perform heat fixing, a storage recess for holding the lubricant is provided in the guide member along a width direction orthogonal to a sheet passing direction of the sheet-like recording material. The recess is configured so that the amount of lubricant that can be stored in the storage recess is different in the width direction.

  According to the fixing device having such a configuration, since the lubricant is confined in the storage recess provided in the guide member, even if the amount of the lubricant is increased, the lubricant is lubricated inside the fixing film without leaking outside. Even if the lubricant is deteriorated and the lubricant is deteriorated in the non-sheet passing region where the chatter noise of the fixing film is likely to occur particularly at high temperatures, the deterioration can be supplemented quantitatively. The high-frequency vibration based on the deterioration of the lubricant is suppressed.

  Further, in the fixing device according to claim 2 of the present invention, a plurality of the storage recesses in claim 1 are arranged along the width direction orthogonal to the sheet passing direction of the sheet-like recording material. In the apparatus, the plurality of storage recesses in claim 2 are configured to have different capacities for storing the lubricant, and in the fixing device according to claim 4, the plurality of storage recesses in claim 2 have physical properties. Different lubricants are stored.

  According to the fixing device having such a configuration, it is possible to change the amount or physical properties of the lubricant corresponding to the temperature difference generated between the sheet passing area and the non-sheet passing area of the sheet-like recording material. In particular, high-frequency vibration based on the deterioration of the lubricant is reliably suppressed in the non-sheet passing region where the temperature is high.

  On the other hand, in the fixing device according to a fifth aspect of the present invention, the storage concave portion according to any one of the first to third aspects is formed from a groove portion, and the groove portion constituting the storage concave portion is formed in the sheet shape with respect to the heater. In the fixing device according to the third aspect of the present invention, the groove portion in the fifth aspect of the present invention is disposed on the upstream side in the sheet feeding direction of the recording material. The height H1 is formed to be larger than the height H2 of the groove wall surface on the downstream side (H1> H2). Furthermore, in the fixing device according to claim 7 of the present invention, a passage for guiding the lubricant toward the heater is formed on the groove wall surface on the downstream side in the sheet passing direction of the sheet-like recording material according to claim 5. Has been.

  According to the fixing device having such a configuration, even if the lubricant overflows from the groove of the storage recess, the lubricant is fixed from the upstream side of the heater to the fixing nip portion that is a sliding portion with the fixing film. As a result, it will flow out well, and a good lubricating function can be achieved.

  In the fixing device according to an eighth aspect of the present invention, the groove portion constituting the storage concave portion in the first aspect is provided within a range corresponding to the image forming area.

  According to the fixing device having such a configuration, the lubricant is held in the image forming region, and external leakage from both ends in the width direction of the fixing film is well prevented.

  An image forming apparatus according to a ninth aspect of the present invention includes the fixing device according to any one of the first to eighth aspects, and the operation according to the present invention described above is similarly applied to the image forming apparatus. It has come to be obtained.

  As described above, in the fixing device and the image forming apparatus according to the present invention, the guide member of the fixing film is provided with the storage concave portion that holds the excess amount of the lubricant so that the lubricant is confined inside the fixing film. Even if the amount of the agent is increased, it is configured to hold the lubricant satisfactorily without causing external leakage, so that the lubricant is surely prevented from overflowing from both ends in the width direction of the fixing film. As a result, it is possible to eliminate image defects due to the wraparound of the lubricant to the surface of the fixing film and to maintain good slidability of the fixing film for a long period of time. It is possible to prevent the generation of abnormal noise and extend the life of the fixing film.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Prior to that, the overall structure will be outlined using a laser printer as an example of an image forming apparatus to which the present invention is applied.

  In the laser printer 10 shown in FIG. 1, for example, when image information sent from an external computer is received by a video controller (not shown) provided in the image forming means, the received image information is received. Is converted into light modulation information 11a by the laser emission writing unit 11 and emitted. The light modulation information 11a emitted from the laser emission writing unit 11 is imaged in a spot shape on a photosensitive drum 121 provided as an image carrier in the process cartridge 12 while being scanned in a direction perpendicular to the paper surface. The light spot irradiated on the photosensitive drum 121 that is moved in the sub-scanning direction by being rotated is reciprocated in the main scanning direction (axial direction), thereby causing the above-described document image information on the photosensitive drum 121. An electrostatic latent image corresponding to is formed. Then, an unfixed toner image is formed by supplying developer (toner) to the electrostatic latent image on the photosensitive drum 121 from a developing device 122 that is also integrally provided in the process cartridge 12. It has become so.

  At this time, the process cartridge 12 described above is configured to be attached and detached by being moved in a substantially horizontal direction (left and right direction in the figure) via an appropriate attachment and detachment mechanism (not shown). Is performed in a state where the user grips the operation lever 12a provided on the rear end side portion (right end side portion in the figure) of the process cartridge 12 by hand. An inner cover 12b and a front cover 12c made of plate-like members are provided on the rear side (right side in the figure) of the process cartridge 12 so as to be openable and closable. It is locked in the state. The inner cover 12b and the front cover 12c are configured to be opened and closed by rotating around the rotation fulcrums 12d and 12e provided at the lower end portions of the respective members. The lock mechanism is fixed at the closed position shown in the figure, and is also configured to be opened in a rotatable state by a release mechanism (not shown).

  On the other hand, a main paper feeding unit 13 for feeding a sheet-like recording material such as a sheet-like recording material cut to a specified size is disposed on the lower side of the apparatus main body. A box-shaped cassette housing 13a constituting the main paper feeding unit 13 is mounted so as to be detachable from the apparatus main body, and an intermediate support plate provided inside the cassette housing 13a. A sheet-like recording material of an appropriate size (not shown) is stored in a laminated form on the upper surface side of 13b. The lowermost surface in the stacking direction of the sheet-like recording material is supported by the middle support plate 13b, and the middle support plate 13b is urged upward by the paper feeding pressurizing spring 13c. The sheet-like recording material is held in a state where it is lifted upward. In addition, a sensor flag 13d made of a plate-like member bent in a substantially "<" shape is disposed at an upper position on the inner side of the cassette housing 13a described above so as to swing vertically. The bent lower end portion of the sensor flag 13d abuts on the uppermost surface position of the sheet-like recording material stored in the cassette housing 13a by its own weight, so that the presence or absence of the sheet-like recording material in the cassette housing 13a is confirmed. It is to be detected.

  Further, a paper feed roller 13e formed of a cylindrical member is provided at the front end portion (left end portion in the drawing) of the cassette housing 13a in the paper feeding direction. The rotating shaft of the paper feed roller 13e is configured such that the rotational driving force is intermittently switched at an appropriate timing via on / off control of an electromagnetic clutch (not shown). The sheet feeding operation is performed with the uppermost surface in the stacking direction of the sheet-like recording material supported so as to be lifted upward by the plate 13b in contact with the outer peripheral surface of the sheet feeding roller 13e from below. It has come to be. Further, a separation pad (separation member) 13f made of a thin plate-like member so as to be adjacent to the front side with respect to the front end edge (the left end edge in the drawing) of the middle support plate 13b described above, It arrange | positions so that it may press-contact with respect to an outer peripheral surface from the downward side. The separation pad 13f is attached to the upper surface side of the separation rocking table 13g arranged to move up and down at the position directly below the paper feed roller 13e. The separation rocking table 13g is separated and pressurized. By being biased upward by the spring h, the separation pad 13f is always kept in pressure contact with the lower surface side of the paper feed roller 13e.

  Then, the sheet-like recording material stacked in the cassette housing 13a in the main paper feeding unit 13 passes through the pressure nip portion with the separation pad 13f by the rotation of the paper feeding roller 13e so as to pass through the paper feeding path. 14 is transferred to the side of the photosensitive drum 121 while facing the nip portion of the pair of registration rollers 15 and 15 provided in the paper feeding path 14 while taking an appropriate timing. It is configured to be sent to the area.

  On the other hand, the transfer roller 17 as a contact transfer member is disposed in contact with the surface of the photosensitive drum 121 in the transfer area of the photosensitive drum 121 described above. A transfer bias is applied to the transfer roller 17, and the unfixed toner image formed on the photosensitive drum 121 is electrostatically transferred onto the sheet-like recording material by the transfer bias. . Further, the toner remaining on the photosensitive drum 121 after the transfer is scraped off by the sliding contact force of the cleaning blade 123 arranged so as to come into pressure contact with the surface of the photosensitive drum 121.

  Further, the sheet-like recording material to which the unfixed toner image has been transferred is fed toward a fixing unit (fixing device) 18 and is shown in FIGS. 2 and 3 through an inlet guide 18g of the fixing unit 18. The fixing film 18a as the fixing heating means and the pressure roller 18b as the fixing pressure means are introduced into the fixing nip portion N which is a mutual pressure contact portion. In particular, as shown in FIG. 3, in the fixing nip portion N described above, a sheet-like shape is formed by the heat energy applied from the heater / heater 18c through the fixing film 18a and the pressing force by the pressure roller 18b. A configuration in which the toner on the recording material P is melted, and the molten toner penetrates and is fixed in the sheet-like recording material P, whereby heat fixing is performed and a permanent image is formed on the sheet-like recording material. Has been made.

  The sheet-like recording material P after the toner image is fixed by passing the paper through the fixing unit 18 in this way is carried out from the fixing nip portion N between the fixing film 18a and the pressure roller 18b. However, the sheet-like recording material P carried out from the fixing nip N is guided to the paper discharge side along the recording material guide member 18d, and is intermediate between the intermediate conveyance roller 19a provided on the paper discharge side. A pair of intermediate conveying rollers constituted by the conveying roller 19b is conveyed so as to pass through the fixing flapper 21. Further, as shown in FIG. 4, the paper is discharged onto the stacking tray 23 by a pair of paper discharge rollers constituted by a paper discharge roller 22a and a paper discharge roller 22b.

  Here, the fixing film 18a provided in the above-described fixing unit 18 is formed of a belt-like annular member, and the shape of the fixing film 18a when the fixing film 18a is rotated is particularly as shown in FIG. It arrange | positions so that it may guide by the film guide member 18e. A part of the inner surface of the fixing film 18a is configured to slide in close contact with the surface of the heater 18c, but the contact sliding between the fixing film 18a and the heater 18c is performed. A heat-resistant lubricant such as grease (not shown) is interposed in the moving part. The heat resistant lubricant has been used year by year in response to an increase in fixing speed in recent years. However, the surplus lubricant due to the increase in the used amount is applied to the above-described film guide member 18e. It is held inside the provided storage recess 18f.

  That is, the storage recess 18f according to the present embodiment has a width direction (FIG. 3 and FIG. 3) that is substantially perpendicular to the sheet passing direction of the sheet-like recording material P (the arrow direction from the lower side to the upper side in FIG. It is formed from an elongated groove portion extending so as to form a substantially U-shaped cross section along the direction perpendicular to the plane of FIG. A plurality of (three bodies) elongated grooves constituting the storage recess 18f are arranged in a substantially straight line in the range corresponding to the image forming region in the width direction (the direction perpendicular to the paper surface in FIGS. 3 and 5). The total length of the plurality of storage recesses 18f is set to a length that does not protrude outward from the image forming area. The plurality of storage recesses 18f are arranged at positions close to the upstream side (the lower side in FIG. 5) in the transport direction of the sheet-like recording material P with respect to the heater 18c.

  Here, the storage recess 18f according to the present embodiment has a configuration corresponding to the A4R size recording paper corresponding to the narrow width size paper among the sheet-like recording material P actually used. That is, when a narrow A4R size paper is continuously passed, the temperature of the non-paper passing area is higher than the paper passing area of the film guide member 18e described above. For this reason, the lubricant present in the non-sheet passing region rapidly deteriorates, and there is a possibility that abnormal noise based on the so-called chatter phenomenon may occur. Therefore, in the present embodiment, as shown in FIG. 6 in particular, the plurality of storage recesses 18f described above correspond to the sheet passing area S2 and the non-sheet passing areas S1 and S1 on both sides thereof, for a total of three. It is formed from an elongated groove portion of the body. Each of these three elongated grooves is arranged so as to be substantially aligned along the width direction orthogonal to the sheet passing direction, and is applied and stored in the non-sheet passing regions S1 and S1 that are at a high temperature. The volume of the lubricant is set to be larger than the volume of the lubricant applied and stored in the sheet passing area S2.

  According to the fixing device according to the present embodiment having such a configuration, the lubricant (grease) is contained in the storage recess 18f provided in the film guide member 18e. Is increased, or even if the temperature of the heater 18c rises, the lubricant may become liquid, and the lubricant does not leak outside, that is, on the inner side of the storage recess 18f, that is, It is favorably held on the inner side of the fixing film 18a.

  In particular, in the present embodiment, since the storage recess 18f is disposed on the upstream side of the heater 18c, the lubricant is held on the upstream side of the heater 18c. As a result, even if the lubricant overflows from the storage recess 18f, the lubricant that has flowed out flows out toward the fixing nip portion N, which is a sliding portion between the heater 18c and the fixing film, A good lubricating function can be achieved.

  In addition, since the storage recess 18f in the present embodiment is disposed inside the image forming area, the lubricant is held in the image forming area, and external leakage from both ends in the width direction of the fixing film 18a occurs. Well prevented.

  Further, a plurality of (three) storage recesses 18f in the present embodiment are arranged for the sheet passing area S2 and the non-sheet passing areas S1, S1 along the width direction orthogonal to the sheet passing direction of the sheet-like recording material P. In addition, since the capacities in the non-sheet passing areas S1 and S1 which are high in temperature are increased, the deterioration of the lubricant in the non-sheet passing areas S1 and S1 where the chatter noise of the fixing film is likely to occur particularly at high temperatures. Even if this occurs, the deterioration can be supplemented quantitatively, and high-frequency vibration based on the deterioration of the lubricant is suppressed.

  At this time, if the lubricants having different viscosities are stored in the respective storage recesses 18f, and the viscosity of the lubricant in the non-sheet passing regions S1 and S1 that are particularly high in temperature is increased, the above-described operation is performed. The chatter noise of the fixing film in the non-sheet-passing areas S1 and S1 is extremely well reduced.

  Instead of changing the viscosity of the lubricant in each storage recess 18f, other physical properties of the lubricant can be made different.

  Further, the configuration of the storage recess 18f in the above-described embodiment adopts A4R size paper as narrow size paper, but like other LRR-R paper, LEGAL paper, B5, B4, A5 paper, etc. Of course, it is also possible to configure corresponding to other paper width narrower than the image area of the film guide member 18e. Furthermore, it is possible to provide a storage recess at a position corresponding to the non-sheet passing area of each recording sheet, or to change the capacity of each storage recess as appropriate. Furthermore, lubricants having different physical properties such as viscosity may be applied to appropriate positions as needed, and the application position at that time is not limited.

  On the other hand, in the embodiment shown in FIG. 7 in which the same reference numerals are assigned to the same components as those in the above-described embodiment, the groove depth of the elongated groove portion constituting the storage recess 38f, that is, the groove wall surface The height is different between the upstream side and the downstream side in the conveyance direction of the sheet-shaped recording material. More specifically, the height H1 of the groove wall surface on the upstream side in the sheet recording material conveyance direction is formed to be larger than the height H2 of the groove wall surface on the downstream side (H1> H2).

  According to the fixing device according to the embodiment having such a configuration, even if the lubricant overflows from the elongated groove portion of the storage recess 38f, the lubricant has a sheet-like recording in which the height of the groove wall surface is low. It flows out toward the fixing nip portion N which is a sliding portion between the heater 18c and the fixing film through the groove wall surface on the downstream side in the material conveying direction, so that a good lubricating function can be achieved. It has become.

  Further, in the embodiment shown in FIG. 8 in which the same reference numerals are given to the same components as those in the above-described embodiment, the cross-sectional shape of the elongated groove portion constituting the storage recess 48f is the width direction (longitudinal). Direction). That is, the storage concave portion 48f1 having a substantially U-shape as shown in FIG. 5 described above, and the height of the groove wall surface as shown in FIG. The storage recesses 48f2 that are different from those on the downstream side are arranged alternately along the longitudinal direction.

  In the fixing device according to the embodiment having such a configuration, an appropriate amount of lubricant can be allowed to flow out from the elongated groove portion of the storage recess 48f, and the appropriate amount of lubricant is supplied to the heater 18c and the fixing film. A good lubricating function can be obtained by supplying to the fixing nip portion N which is a sliding portion with respect to 18a.

  As mentioned above, although the embodiment of the invention made by the present inventor has been specifically described, the present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made without departing from the scope of the invention. Nor.

  For example, in the above-described embodiment, the present invention is applied to a printer, but the present invention can be similarly applied to other image forming apparatuses such as a copying machine.

  The image forming apparatus according to the present invention described above can be widely applied to a wide variety of image forming apparatuses such as copying machines as well as image forming apparatuses such as printers.

It is side explanatory drawing showing the internal schematic structure of the printer to which this invention is applied. FIG. 2 is a partial vertical cross-sectional explanatory view showing an enlargement of a fixing film and a pressure roller of a fixing device employed in the printer shown in FIG. 1. FIG. 2 is a side cross-sectional explanatory diagram illustrating a configuration of a fixing unit (fixing device) according to an embodiment of the present invention illustrated in FIG. 1 and the vicinity thereof. FIG. 4 is an external perspective view showing the back side of the fixing unit (fixing device) according to the embodiment of the present invention shown in FIG. 3. FIG. 4 is an explanatory side cross-sectional view illustrating an enlarged portion of a fixing film and a guide member of a fixing unit (fixing device) according to an embodiment of the present invention. FIG. 6 is an explanatory bottom view illustrating a surface structure on the fixing nip portion side of a film guide member of the fixing unit (fixing device) illustrated in FIG. 5. FIG. 6 is an explanatory side cross-sectional view illustrating an enlarged portion of a fixing film and a guide member of a fixing unit (fixing device) according to another embodiment of the present invention. FIG. 10 is an enlarged side cross-sectional explanatory view showing a fixing film guide portion of a fixing unit (fixing device) according to still another embodiment of the present invention.

Explanation of symbols

10 Laser printer (image forming device)
12 Process Cartridge 121 Photosensitive Drum 122 Developing Device 13 Main Paper Feed Unit 14 Paper Feed Path 15 Registration Roller 18 Fixing Unit (Fixing Device)
18a Fixing film (fixing heating means)
18b Pressure roller (fixing pressure means)
18c Heating / heating heater 18d Recording material guide member 18e Film guide member (guide member having a rotational shape of the film)
18f Reservoir recess (elongate groove)
18g Film restricting member (Thrust restricting member in the thrust direction)
19a Intermediate conveyance roller 19b Intermediate conveyance roller 21 Fixing flapper (second guide protrusion)
22a Paper discharge roller 22b Paper discharge roller N Fixing nip P Sheet-like recording material 38f, 48f Reservoir (recessed slot)

Claims (9)

An annular fixing film guided by a guide member when moving is arranged so as to slide while closely contacting the surface of the heater with a lubricant,
The unfixed image on the sheet-like recording material is heat-fixed by introducing the sheet-like recording material into the fixing nip portion where the fixing film and the fixing pressure unit are in pressure contact with each other. In the fixing device,
A storage recess for holding the lubricant is provided in the guide member along a width direction orthogonal to the sheet passing direction of the sheet-like recording material,
The fixing device is configured such that the amount of lubricant that can be stored in the storage recess is different in the width direction.   The fixing device according to claim 1, wherein a plurality of the storage recesses are arranged along a width direction orthogonal to a sheet passing direction of the sheet-like recording material.   The fixing device according to claim 2, wherein the plurality of storage recesses are configured to have different capacities for storing the lubricant.   The fixing device according to claim 2, wherein lubricants having different physical properties are stored in the plurality of storage recesses.   4. The storage concave portion is formed of a groove portion, and the groove portion constituting the storage concave portion is arranged on the upstream side in the sheet passing direction of the sheet-shaped recording material with respect to the heater. The fixing device according to any one of the above.   The groove portion constituting the storage recess is formed such that the height H1 of the groove wall surface on the upstream side in the sheet passing direction of the sheet-like recording material is larger than the height H2 of the groove wall surface on the downstream side (H1>). 6. The fixing device according to claim 5, wherein H2).   6. The fixing device according to claim 5, wherein a passage for guiding the lubricant toward the heater is formed in a groove wall surface on the downstream side in the sheet passing direction of the sheet-like recording material.   The fixing device according to claim 1, wherein the groove portion constituting the storage recess is provided in a range corresponding to the image forming region. An image forming apparatus comprising the fixing device according to claim 1.

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