JP2009151231A - Image heating apparatus and image heating rotational body used in image heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a scratch on the surface of a fixing roller caused by, for example, insertion of paper. <P>SOLUTION: The image heating apparatus includes: the fixing roller 110 having a releasing layer on its surface; a heating means for heating the fixing roller 110; and a pressure roller (backup member) 111 forming a nip together with the fixing roller 110, by which a recording member with images thereon is pinched and conveyed. In the image heating apparatus, the fixing roller 110 and a sliding member 112 arranged in contact with the surface of the fixing roller 110 are relatively moved in a direction intersecting with the rotational direction of the fixing roller 110 while the fixing roller 110 is heated by the heating means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image heating apparatus suitable for use as a fixing device mounted in an image forming apparatus such as an electrophotographic copying machine or a laser beam printer, and a rotating body for image heating used in the image heating apparatus.

  Conventionally, as an image forming apparatus, a fixing device that heat-fixes an unfixed developer formed or supported on a recording material indirectly or directly on a recording material by an appropriate image forming process means such as an electrophotographic process as a permanently fixed image on the recording material surface. Heat roller type devices are widely used.

  In recent years, oil-less fixing for fixing unfixed images made of toner containing a release agent has become widespread, and in response to this, the fixing roller has an elastic layer made of silicone rubber or fluoro rubber on an AL or iron core. The surface layer is provided with a release layer made of a fluororesin tube or a coating. Such an oil-less fixing method has the advantage that there is no unevenness in gloss, such as oil streaks, unlike the oil fixing method. In addition to the improvement in toner for high-gloss recording materials such as coated paper, Furthermore, it is possible to pursue high image quality.

  However, the surface layer of the fixing roller having a release layer on the surface layer has a problem that it gradually becomes rough due to an attack (damage caused by the paper) due to paper passing, paper dust, offset toner, and the like. Conventionally, there are the following patent documents regarding dirt and roughness on the surface layer of the fixing roller.

  Patent Document 1 proposes a method of bringing a cleaning web containing metal into contact with the fixing roller in order to keep the surface of the fixing roller constant in conventional oil fixing without a release layer. However, since the cleaning web abuts the surface of the fixing roller such as silicone rubber to create a new surface, the elastic layer gradually disappears, so the life is only about 50,000 sheets. . Also, according to Patent Document 2 regarding a cleaning web containing metal, the surface roughness of the scraped surface is about 3 μm in terms of Rz (ten-point average roughness). If it is cut to 3 μm with Rz, the scratches are generated as gloss unevenness on the image.

In addition, the following patent documents have been proposed which actively control the surface of the fixing roller. Japanese Patent Application Laid-Open No. H10-228561 proposes that the surface state of the surface state changing member is transferred to the fixing roller after the surface layer of the fixing roller is heated and melted, thereby enabling surface repair and gloss control. However, heating to the vicinity of the melting point of the fixing roller surface and cooling to normal temperature control are indispensable, and it takes a long time for the repair operation. Further, the material of the release layer on the fixing roller surface layer is limited to a material having a low melting point. There are challenges.
Japanese Patent Publication No. 7-89257 JP-A-2-266383 JP 2005-266785 A

  The inventor of the present invention, particularly with respect to the attack due to paper passing, among the problems that the surface of the fixing roller having a release layer on the surface layer is attacked due to paper passing and gradually becomes rough due to dirt such as paper dust and offset toner. However, the following things have been found.

  In other words, when a large number of recording sheets are passed through the fixing roller at a fixed position, (1) the paper passing area, (2) the non-passing area, and (3) the non-passing area on the surface of the fixing roller. It was found that the surface roughness of the fixing roller differs at the paper edge passing portion at the boundary of the paper area.

  The surface of the fixing roller having a release layer such as a fluororesin on the surface is a mirror surface, and the surface roughness is usually about 0.1 μm to 0.3 μm in Rz. On the other hand, the recording paper passing portion on the surface of the fixing roller is gradually roughened by the attack of paper fibers, internal and external additives, and scratches are gradually increased to about 1.0 μm in Rz.

  Since the edge portion of the paper has burrs generated when the paper is cut, the influence on the fixing roller is large, and the surface roughness is gradually increased to about 1.0 to 2.0 μm in Rz. Paper burrs are likely to occur when the cutting blade is worn out and the sharpness deteriorates in the cutting process from a large format.

  In the non-sheet passing portion of the surface of the fixing roller, there is no recording paper passing, and the surface of the fixing roller is in contact with a pressure member that forms a fixing nip portion together with the fixing roller, and the scratches are about 1.0 μm in Rz. It grows slowly.

  As a result, the surface roughness of the fixing roller after continuous paper passing increases in the order of (3) paper edge passing portion> (1) paper passing area> (2) non-paper passing area> initial state (new state). Accordingly, it can be seen that as the use proceeds, the surface state of the fixing roller varies depending on the position in the generatrix direction.

  Next, the surface condition of the fixing roller and the gloss unevenness on the image will be described.

  When fixing an unfixed toner image, the fixing device applies pressure and heat to the toner. At this time, the minute surface state of the fixing roller is transferred to the surface of the toner image after fixing. If the surface state on the fixing roller is different, a difference in surface state is generated on the toner image correspondingly, resulting in uneven gloss (gloss unevenness). This phenomenon is conspicuous with coated paper having good surface smoothness, and is a level that cannot be seen with high-quality paper used in offices. According to the inventor's study, the occurrence of scratches due to paper edge depends on the paper type, but the level of paper with poor burr at the time of paper cutting is bad, and paper edge damage on other thick paper or coated paper is It was below the level of this example.

  Generally, gloss is recognized as high gloss when the reproducibility of the specular reflection light image is high, and low gloss when the reproducibility is low or absent. For example, when an image such as a silver salt photograph is viewed under fluorescent light illumination, not only the light from the fluorescent light is reflected, but also the shape of the fluorescent light is reflected, regardless of whether it is conscious or not. We recognize that. This indicates that the surface state of the photographic image is a mirror surface state with less unevenness.

  On the other hand, in the case of low gloss, the opposite is true: the surface state of the image is largely uneven, the light from the fluorescent lamp is irregularly reflected, and its shape does not appear on the image. Thus, there is a correlation between the unevenness of the surface state on the image and the gloss.

  Since there are various sizes of the recording paper, there are a number of scratches caused by the passage of the paper edge in the generatrix direction on the surface of the fixing roller. Therefore, when fixing a highly glossy coated paper that requires high image quality, streaks that cause low gloss are attached, or a difference in gloss due to a difference in surface roughness of the fixing roller is generated.

  In addition, scratches on the surface of the fixing roller are superposed on fine rubbing scratches that cannot be visually recognized, or the surface of the fixing roller is slightly scraped to expose a new surface. There is a way to do it. However, although it is very small, as a problem on the means of scratching the surface, there is a problem that the glossiness is lowered because the surface property is lowered. Furthermore, when using a sliding member for superimposing fine rubbing scratches or scraping the surface layer slightly, especially when using a sliding member in a fixed manner, paper dust or foreign matter may be caught in the circumferential direction. There was a problem that even a secondary problem such as a vertical streak caused by an entering wound occurred.

  The present invention for solving the above-described problems includes a rotating body having a release layer on the surface, a heating means for heating the rotating body, and a nip portion for nipping and conveying a recording material carrying an image together with the rotating body. A sliding member that contacts the surface of the rotator and stretches the release layer in a crossing direction intersecting the rotation direction of the rotator to deform it into a scaly shape. It is characterized by having.

  Further, the present invention relates to an image heating rotating body used as a rotating body in contact with an image on a recording material of an image heating apparatus for heating an image on a recording material while sandwiching and conveying a recording material carrying an image. It has a scale-like mold release layer stretched in a crossing direction intersecting with a rotation direction of the rotating body.

  According to the present invention, the surface of the rotating body is scratched on the surface of the rotating body because it has a sliding member that contacts the surface of the rotating body and stretches the release layer in the intersecting direction intersecting the rotating direction of the rotating body to deform it into a scale shape. Can be prevented from occurring.

  Further, if a rotating body having a scale-like release layer stretched in a crossing direction intersecting with the rotating direction of the rotating body is used, it is possible to shorten the time required for repairing a wound.

Example 1
Example 1 of the present invention will be described below. First, an image forming apparatus in which the image heating apparatus of this embodiment is mounted as a fixing device will be described, and then the image heating apparatus according to the present invention will be described in detail.

[Image forming apparatus body configuration]
A general method for forming an unfixed toner image on a recording material, which is a heated body, will be described with reference to a schematic diagram shown in FIG.

  The image forming apparatus 50 according to the present exemplary embodiment sequentially transfers four color toner images of yellow, magenta, cyan, and black onto a single recording material P carried on the recording material conveyance belt 9, thereby generating one image. Is a full-color printer of the type that forms Around the photosensitive drum 1, the charger 2, the exposure device 3 that irradiates the photosensitive drum 1 with laser light according to image information, and the static formed on the photosensitive drum 1 in the order of rotation (in the direction of arrow R <b> 1). A developing unit 5 for developing the toner by attaching toner to the electrostatic latent image is disposed. A transfer roller 10 to which a voltage for transferring a toner image from the photosensitive drum 1 to the recording material P is applied is disposed on the opposite side of the recording material conveyance belt 9 from the side on which the photosensitive drum 1 is disposed. Reference numeral 16 denotes a photosensitive drum cleaner.

  When image formation is performed, the surface of the photosensitive drum 1 is charged negatively by the charger 2. The negatively charged photosensitive drum 1 is scanned by a laser beam L emitted from the exposure unit 3 to form an electrostatic latent image on the surface (the surface potential of the exposed portion is increased). The developing unit 5 containing yellow toner of the first color causes the toner to adhere to the electrostatic latent image portion on the photosensitive drum, thereby forming a toner image on the photosensitive drum 1.

  On the other hand, the recording material transport belt 9 is supported by two support shafts (a driving roller 12 and a tension roller 14), and is rotated in the direction of arrow R3 by the driving roller 12 rotating in the direction of arrow R4 in the drawing. When the recording material P is fed by the paper feed roller 4, the recording material P is charged by the suction roller 6 to which a positive polarity bias is applied, and is electrostatically attracted and transported onto the recording material transport belt 9. When the recording material P is conveyed to the transfer nip N1, a positive transfer bias is applied from a power source (not shown) to the transfer roller 10 that is driven to rotate by the recording material conveyance belt 9, and the yellow toner image on the photosensitive drum 1 is The image is transferred onto the recording material P at the transfer nip N1. After the transfer, the photosensitive drum 1 is cleaned by a photosensitive drum cleaner 16 having an elastic blade.

  The series of image forming processes of charging, exposure, development, transfer, and cleaning described above are sequentially performed for each developing cartridge of magenta M30 for the second color, cyan C30 for the third color, and black k30 for the fourth color. The four color toner images are superimposed on the upper recording material P. The recording material P carrying the four-color toner images is conveyed to the fixing device 100, and the toner image on the recording material P is heat-fixed on the recording material P and then discharged out of the printer.

[Fixing device (image heating device)]
Next, the fixing device 100 will be described below.

  As described above, the fixing device 100 is provided with a release layer such as “low-gloss streaks at the paper edge passing position”, “gloss difference between the paper passing area and the non-paper passing area”, and “longitudinal streaks due to paper dust or foreign matter” This fixing device is intended to suppress the occurrence of image defects due to scratches on the surface.

  Conventionally, in the fixing device as described above, the surface of the fixing roller is gradually damaged due to an attack caused by passing paper, or dirt such as paper dust and offset toner. In addition, as a conventional countermeasure method, the glossiness of the image is reduced due to the deterioration of the surface property that a fine scratch is made in a method of keeping the surface property constant (refreshing) using a sliding member or the like. Furthermore, especially when foreign matter such as paper dust is caught between the sliding member and the fixing roller, the rotation of the fixing roller causes the foreign matter to rub against the same part of the surface of the fixing roller. Deep scratches in the direction. In this embodiment, the sliding member and the fixing roller are slid relative to each other in a direction different from the rotation direction of the fixing roller, so that scratches in the rotation direction of the fixing roller can be prevented and repaired. Despite the use of the sliding member, high glossiness can be maintained. This will be described in detail below.

  FIG. 1 is a schematic cross-sectional view of the fixing device in this embodiment. In FIG. 1, a fixing roller (rotating body having a release layer on the surface) 110 has a rubber hardness of 20 ° (JIS-A: 1 kg load) as an elastic layer 116 on a hollow metal core 117 made of AL having an outer diameter of 68 mm. Silicone rubber is molded into 1.0 mm, and a release layer 118 having a thickness of 30 μm and an outer diameter of φ70 mm made of perfluoroalkoxy resin (PFA) is formed on the elastic layer 116 as a release layer. The release layer 118 may be a tube coated or a surface coated with a paint, but in this example, a tube having excellent durability was used. As a material for the release layer 118, a fluororesin such as polytetrafluoroethylene resin (PTFE) or tetrafluoroethylene-hexafluoropropylene resin (FEP) may be used in addition to PFA.

  If the surface hardness of the fixing roller 110 is low, the width of the contact heating portion N1 can be obtained even at a light pressure. However, if the surface hardness is too low, the durability deteriorates. Therefore, in this embodiment, Asker-C hardness (4.9 N load) is used. 40 to 45 °.

  The pressure roller (backup member) 111 is formed by molding 1.0 mm of silicone rubber having a rubber hardness of 20 ° (JIS-A: 1 kg load) as an elastic layer 122 on a hollow cored bar 121 having an outer diameter of 48 mm. The one having an outer diameter of 50 mm and having a surface coated with a release layer 123 made of fluororesin having a thickness of 30 μm was used. The pressure roller 111 is pressed by a pressure roller pressure spring 124 via a bearing 125 with a force of 800 N in the direction of arrow A2 in the figure, contacts the fixing roller 110, and passes through the fixing nip portion N2 having a width of 10 mm to the fixing roller. It is formed together with the fixing roller 110 and rotated (arrow R3 in the figure).

  The fixing roller 110 has a halogen heater (heating means) 126 as a heating source inside, and is adjusted to 180 ° C. by a temperature sensor (not shown) and a temperature control circuit (not shown). Further, the fixing roller 110 is rotated by a rotating means (not shown) in the direction of arrow R2 in the drawing at a surface moving speed of 220 mm / sec.

  On the outer peripheral surface of the fixing roller 110, a sliding member that slides on the outer surface of the fixing roller 110 as a sliding member that contacts the surface of the rotating body and stretches the release layer in a crossing direction that intersects the rotating direction of the rotating body to deform into a scale shape. The moving sliding member 112 contacts to form a contact portion N1.

  The sliding member 112 has a configuration in which the sliding portion heat storage member 113 is held by the heat insulating holder 119, and a sliding layer 120 is provided in a portion that contacts the fixing roller 110. The sliding member 112 is pressed with a force of 180 N in the direction of the arrow A1 in the figure by the pressing spring 114 to form a contact portion N1 having a width of 10 mm. The sliding part heat storage member 113 was an alumina substrate having a width of 12 mm and a thickness of 1 mm, and a glass covered with a thickness of 50 μm as a protective layer thereon. Although the glass surface of the sliding part heat storage member 113 may be brought into direct contact with the surface of the fixing roller 110 and the surface of the fixing roller 110 may be heated, in this embodiment, the surface of the sliding part heat storage member 113 is releasable. The sliding layer 120 having excellent slidability was provided. The sliding layer 120 prevents toner offset to the surface of the fixing roller 110 from adhering to the sliding member 112 and reduces frictional force due to sliding with the fixing roller 110. As the material of the sliding layer 120, it is preferable to use a fluororesin such as PFA excellent in releasability with toner and PTFE excellent in sliding property. If the sliding layer 120 is too thick, the sliding part heat storage member 113 is difficult to store heat, and if it is too thin, the durability is insufficient. Therefore, the thickness is preferably about 1 to 100 μm. In addition, the sliding layer 120 may be coated with a fluororesin directly on the sliding portion heat storage member 113 in order to reduce the contact thermal resistance with the sliding portion heat storage member 113, and has a sheet shape with excellent durability and surface properties. May be used. When used in the form of a sheet, since it can be installed so as to cover the upstream and downstream edge portions of the sliding portion heat storage member 113, there is an advantage that the fixing roller 110 can be protected from the edge of the sliding portion heat storage member 113. In the present embodiment, a PFA sheet having a thickness of 50 μm is used for the sliding layer 120 so as to cover the edge of the sliding part heat storage member 113.

  When the recording material P to which the unfixed toner image T is transferred is conveyed to the fixing nip portion N2 by a conveyance unit (not shown), the heat on the surface of the fixing roller 110 is transferred to the unfixed toner image T and the recording material P. The toner image T is fixed on the surface of the recording material P.

  Next, a means for stretching the release layer 118 on the surface of the fixing roller, which is a feature of the present invention, in a scaly manner, an effect of suppressing the generation of scratches, an effect of repairing scratches, and maintaining high surface roughness are described below.

  FIG. 2 is a front view of the heat fixing apparatus of this embodiment. The sliding member 112 is fixed, and the pressure roller 111 fixed in the axial direction is driven to rotate in the direction of the arrow R3 by the rotation of the fixing roller 110 in the direction of the arrow R2. The fixing roller 110 can move (slide) in the axial direction (bus line direction), and is pressed with a force of 49 N in the direction of the arrow A4 by the slide pressure spring 130 from one side, and slides in the direction of the arrow A5. On the other hand, a slide cam 129 is provided on the opposite side of the fixing roller 110 from the slide pressure spring 130, and is rotated about a slide cam shaft 133 by a rotating means (not shown) in the direction of arrow R6. Yes.

  FIG. 3 shows a view in which the slide cam 129 is rotated 180 ° with respect to FIG. When the slide cam 129 rotates 180 °, the fixing roller 110 is pushed by the slide cam 129 and slides in the arrow A6 direction. When the slide cam 129 further rotates 180 ° in the direction of the arrow R6, the fixing roller 110 is pressurized in the direction of the arrow A4 by the slide pressure spring 130 and returns to the position of FIG. That is, while the slide cam 129 rotates in the direction of arrow R6, the fixing roller 110 reciprocates in the axial direction. When the fixing roller 110 rotates, the slide cam 129 rotates in the direction of the arrow R6 to reciprocate the fixing roller 110.

  Here, in FIG. 4, the frictional force received by the sliding with the sliding member 112 during the reciprocating motion of the fixing roller 110 will be described. Since the fixing roller 110 is rotating, the contact portion N1 that is in contact with the sliding member 112 receives a frictional force Fr opposite to the rotation direction. Furthermore, since it reciprocates in the axial direction, it receives a frictional force opposite to the movement. FIG. 4 shows the frictional force Fs received when the fixing roller 110 is moving in the A6 direction. The surface of the fixing roller receives the force F1 as a resultant force of the two frictional forces. Since the fixing roller 110 reciprocates as described above, the force F1 has a component other than the rotation direction, and the magnitude of the force also changes periodically with time.

  In the conventional configuration, when a foreign matter such as paper dust is caught in the contact portion N1, the foreign matter tends to be caught in the contact portion N1 and easily stay. Therefore, if the foreign matter stays at the contact portion N1, the foreign matter scrapes the same portion of the surface of the fixing roller, and deep flaws are generated in the rotation direction of the fixing roller.

  On the other hand, when the configuration of the present embodiment is used, the frictional force received by the foreign matter at the contact portion N1 is also generated in the direction other than the rotation direction of the fixing roller as described above. Is likely to pass through the contact portion N1. Therefore, the foreign matter does not damage the same part of the surface of the fixing roller, and it is possible to prevent deep scratches from occurring on the surface of the fixing roller.

  Further, due to the above-described frictional force F1 and heating from the halogen heater 126, the surface release layer 118 of the fixing roller 110 is stretched in a scaly shape. That is, when the rotating body rotates while being heated by the halogen heater (heating means), the release layer is stretched in the intersecting direction by moving the rotating body in the intersecting direction.

  FIG. 5 (1) is a surface layer of a new fixing roller, and FIG. 5 (2) is a photograph of the surface layer after the fixing roller 110 is reciprocated for 10 minutes by the method described above. The results are observed with a polarizing microscope. In this way, the release layer 118 stretched in a scale shape is generated on the entire surface of the fixing roller 110. The mechanism for repairing deep flaws generated on the surface of the fixing roller in the configuration of this embodiment is as follows.

  As described above, the release layer stretched in a scaly manner on the entire surface of the fixing roller covers the scratches on the surface of the fixing roller 110 so that the scratches on the fixed image cannot be seen. If the release layer 118 stretched in a scale shape cannot cover all of the scratches generated on the fixing roller 110 until the scratches can no longer be seen, the fixing layer can be fixed. The effect is that the scratches on the image are not visible.

  Here, FIGS. 6A and 6B are cross-sectional views of the surface of the fixing roller 110 observed with a scanning electron microscope (SEM). 6A is a view of the surface layer of a new fixing roller 110, and FIG. 6B is a view of the surface layer after the fixing roller 110 is reciprocated by the above-described method. The surface layer of FIG. 6 (1) is smooth, whereas the surface layer of FIG. 6 (2) shows that the release layer stretched in a scale shape covers the wound and the wound is repaired. .

  As described above, in order to obtain the effect of stretching the release layer 118 in a scale shape, the frictional force and temperature applied to the surface of the fixing roller 110 are necessary.

First, the frictional force applied to the surface of the fixing roller 110 includes the frictional force F1 generated by the sliding of the fixing roller 110 and the sliding member 112 as described above. In order to obtain this frictional force F1, in this embodiment, the surface pressure peak value of the contact portion N1 is set to 1.2 × 10 ⁵ (N / m ² ). In order to obtain the frictional force F1 that effectively stretches the release layer 118 in the form of flakes, the surface pressure peak value of the contact portion N1 is preferably 9.8 × 10 ⁴ (N / m ² ) or more.

  Next, as a temperature for obtaining the effect of stretching the release layer 118 in the form of flakes, a temperature equal to or higher than the glass transition point (TG) of the release layer 118 is required. The release layer PFA used in this example has a glass transition point of about 118 ° C. By setting the surface temperature of the fixing roller when the release layer is stretched to 180 ° C., which is the target temperature of the surface of the fixing roller when fixing the toner image on the recording paper, the release layer 118 is set. Can be effectively stretched into a scaly shape.

  Even when the fixing roller 110 is fixed and slides only in the rotation direction with the sliding member 112 in the conventional configuration in which the surface of the release layer is rubbed by sliding, the above-described frictional force and temperature conditions are satisfied. Thus, the release layer 118 is stretched in a scaly shape. However, the effect of repairing the scratch as in this embodiment cannot be obtained. The reason is as follows.

  As described above, in the conventional configuration, the frictional force Fr applied to the surface of the fixing roller 110 is only in the rotation direction. In this case, since the release layer 118 is stretched in the form of flakes in the rotational direction, the scratches deeply generated in the rotational direction are covered and cannot be repaired. FIG. 7 (1) shows that the surface layer polarization microscope observation image and the state of the surface layer after the fixing device is driven for 10 minutes with the surface temperature of the fixing roller 110 adjusted to 180 ° C. in the conventional configuration are easily understood. Is shown schematically in FIG. As shown in the figure, the release layer 118 is stretched in a scaly shape so as to follow the wound, so that the wound cannot be covered.

  On the other hand, in this embodiment, as described above, since the fixing roller 110 reciprocates in the axial direction, the frictional force applied to the surface of the fixing roller 110 can have components other than the rotation direction. Therefore, as shown in FIG. 7 (2) with a polarizing microscope photograph and a schematic diagram, the release layer 118 is stretched in a scaly shape in a random direction other than the rotation direction (in a drown state). It is possible to cover the wound deeply generated and repair the wound.

  Further, in this way, when the release layer 118 on the surface of the fixing roller 110 is deformed in a scaly shape, even if foreign matter remains on the contact portion N1 and the fixing roller is scraped, the scratches are intermittently caused by the unevenness of the scaly release layer 118. Therefore, it is possible to obtain an effect of preventing scratches that are difficult to appear as vertical stripes on a fixed image because of interruption. That is, the unevenness of the scale-like release layer 118 acts not only on vertical stripes but also on various scratches such as attacks caused by paper passing and scratches caused by dirt such as paper dust and offset toner, thereby preventing scratches. An effect can be obtained.

  The above-mentioned effect can be obtained when the sliding amount W1 of the fixing roller 110 by the slide cam 129 is about 1 mm. However, the larger the sliding amount W1, the larger the effect. In this embodiment, the sliding amount W1 is 4 mm. Further, if the reciprocating cycle of the fixing roller 110 overlaps with the rotational cycle of the fixing roller 110, the same portion of the surface of the fixing roller is rubbed at the contact portion N1. The prevention of scratches and the effect of repairing scratches are greatly reduced.

  At least one cycle of the fixing roller 110 and one cycle of the fixing roller 110 should not be synchronized. In this embodiment, the sliding speed of the fixing roller 110 is set to 2.45 seconds per reciprocation with respect to one cycle of the fixing roller 110 being about 1.00 seconds.

  In the conventional configuration, the flaw on the fixing roller that has occurred and has not been repaired is transferred to the toner image on the recording material at the time of fixing. In low print rate images such as documents and halftones, the transferred scratches are not noticeable. However, in high print rate images such as solid images and photographs, the transferred scratches are noticeable as gross unevenness and vertical stripes, resulting in poor images. End up. In particular, when glossy paper requiring gloss is used, scratches are conspicuous on the fixed image. Since the toner is sufficiently melted to give gloss and the toner image is smooth, the transferred scratches tend to be noticeable. When the surface roughness (Rz) of the fixing roller 110 is about 6 μm or more, not only glossy paper but also plain paper that does not require gloss may cause vertical streaks depending on the image printing rate. In order not to see the scratch transferred to the toner image on the recording material, the surface roughness Rz needs to be suppressed to 3 μm or less. When Rz is 3 μm or less, gloss unevenness and vertical stripes are not noticeable even when an image having a high printing rate is fixed on glossy paper or the like.

  In the configuration described above, a printing durability test was performed and compared with the conventional configuration. In the printing durability test, images with a printing rate of 5% were continuously printed, and flaws on the fixing roller were checked every 1000 sheets up to 10,000 sheets and every 10,000 sheets after 10,000 sheets. The flaws on the fixing roller were confirmed by measuring the flaw depth with a surface roughness meter and by checking for the presence or absence of vertical streaks on solid images with plain paper and glossy paper. FIG. 8 shows the result of the flaw depth of the fixing roller by the printing durability test. The scale of the horizontal axis indicates that the numerical value 10 is 10,000 sheets.

  In the configuration of the conventional example, the flaw depth (ten-point average roughness Rz) of the fixing roller became 3 μm or more at the time of printing 4000 sheets, and vertical stripes were generated on the solid image of glossy paper. Furthermore, the flaw depth (ten-point average roughness Rz) of the fixing roller becomes 6 μm or more at the time of printing 30,000 sheets, and vertical stripes are generated on the image even when a solid image is formed on plain paper. I have.

  On the other hand, in the configuration of the present embodiment, since the fixing roller 110 slides in a state where the sliding member 112 is in contact, the depth of the flaw of the fixing roller (tenths) is increased to 100,000 sheets which is the life of the fixing device of the present embodiment. The point average roughness Rz) could be suppressed to 3 μm or less. Therefore, even when an image is formed and fixed on glossy paper where the vertical stripes are easily visible, no vertical stripe-like image defect occurs on the solid image until the life of the fixing device.

  Further, even if scaly irregularities are formed on the surface layer of the fixing roller by the method of this embodiment, there is no adverse effect such as a reduction in gloss. The reason is that when the release layer is deformed into a scale shape, it is sufficiently stretched by heating and frictional force, and it is difficult for an extreme step that leads to a decrease in gloss to appear on the surface layer. The surface of the fixing member, that is, the surface of the release layer is the surface of the fixing member, that is, the surface of the fixing member that is finely maintained (refreshed) by using a sliding member or the like as in the conventional configuration. Although the roughness is uniform, the glossiness of the surface is lowered. On the other hand, the surface of the fixing member in the present invention, that is, the surface of the release layer 118 has high gloss and high uniformity of surface roughness.

  FIG. 11 shows a surface angle histogram (measured by Ryoka System Co., Ltd. micromap). The figure shows the surface property by the frequency distribution of the surface angle. The angle is 90 ° as a smooth surface, and the value becomes smaller as the inclination becomes stronger. The higher the frequency of the surface close to the smooth surface (90 degrees), the higher the smoothness. In the image, a portion having a surface angle of 85 degrees or more greatly contributes to glossiness. Compared to the frequency distribution of unused products, the frequency distribution of the conventional sliding method (such as the method of maintaining surface properties by making fine scratches), the frequency of the surface angle of 85 degrees or more significantly decreases, 85 degrees or less It can be seen that the frequency of On the other hand, in the example, although the frequency of the smooth surface (near 90 degrees) is decreased, the frequency increase of 85 degrees or less is small, and the frequency decrease of 85 degrees or more remains large compared to the conventional product. I understand that. Therefore, in this embodiment, it is needless to say that the uniformity of the surface property can be obtained while maintaining the high glossiness of the image.

  In the conventional configuration, when a large amount of small-size paper is passed, the fixing roller 110 may be damaged in the rotational direction due to the paper edge. In the configuration of this embodiment, since the release layer 118 is stretched and has an effect of repairing the scratch, even when a large amount of small-size paper is passed, a serious scratch that causes an image defect occurs on the fixing roller. There is nothing to do.

  In the configuration of the present embodiment described above, the sliding member 112 is fixed and the fixing roller 110 is reciprocated. However, the fixing roller 110 is fixed and the sliding member 112 is reciprocated, or the sliding member 112 is fixed. The fixing roller 110 may be reciprocated. FIG. 9 shows a configuration in which only the sliding member 112 is reciprocated as an example. A mechanism in which the slide pressure spring 130 and the slide cam 129 are arranged at both ends of the sliding member 112 and the fixing roller 110 is reciprocated is applied to the sliding member 112 as it is. Also in this configuration, when the sliding member 112 reciprocates, the frictional force applied to the surface layer of the fixing roller 110 in the contact heating unit N1 has a component other than the rotation direction, and thus the release layer 118 is randomly stretched, and the fixing roller Cover the upper wound and repair the wound. Further, it is possible to prevent the occurrence of scratches for the same reason as described above. In other words, when the rotating body rotates while being heated by the halogen heater (heating means), the release layer is stretched in the intersecting direction by moving at least one of the rotating body and the sliding member in the intersecting direction. I just need it.

  The direction in which the fixing roller 110 and the sliding member 112 are reciprocated is not limited to the axial direction. For example, the sliding member 112 may be configured to be shifted with respect to the rotation axis of the fixing roller 110. FIG. 10 is a top view of a configuration in which the sliding member 112 is displaced with respect to the rotation axis of the fixing roller 110 from an example in which the sliding member 112 is reciprocated in the direction of the rotation axis of the fixing roller 110. As described above, the frictional force Fr generated by the rotation of the fixing roller 110 and the frictional force Fs due to the reciprocating motion of the sliding member 112 are generated (the drawing shows a case where the sliding member 112 is moving in the A8 direction). . Since the resultant force F1 of the frictional forces Fr and Fs has a component in a direction other than the rotation direction of the fixing roller 110, as described above, the generation of a flaw can be prevented and the flaw can be repaired.

  If the shift angle X between the rotation axis of the fixing roller 110 and the longitudinal center axis Z1 of the sliding member 112 becomes too large, the sliding member is uniformly brought into contact with the contact portion. The harmful effects of Accordingly, in this embodiment, the angle is set to 5 °.

  In this embodiment, a PTFE sheet made of fluororesin is used for the sliding layer 120. However, in order to efficiently transmit the heat of the heater to the fixing roller 110, a metal sheet such as aluminum (AL) or SUS may be used. Good.

  As described above, if the fixing roller 110 and the sliding member 112 have a component that slides in a direction different from the rotation direction of the fixing roller 110, the release layer 118 on the surface of the fixing roller 110 is different from the rotation direction. Since the frictional force is applied in different directions, a scale-like release layer is formed on any circumference in the rotation direction of the fixing roller 110, and a flaw repair effect is obtained. Moreover, since it is easy to remove the foreign matter in the heating nip, the occurrence of scratches can be prevented.

  Further, in this embodiment, the rotatable fixing roller 110 is used as the fixing member. However, a fixing belt may be used as the fixing member, and any fixing member having a release layer as described above may be used. Thus, the effect of the invention is not impaired.

(Example 2)
A second embodiment of the present invention will be described below. The same members as those of the first embodiment are denoted by the same reference numerals and numbers as those of the first embodiment, and the description thereof is omitted.

  The release layer 118 of the fixing roller (rotating body for image heating) 110 described in the first embodiment is in the initial stage (new state in which the image forming apparatus has just been purchased) incorporated in the fixing device, as shown in FIG. As shown in Fig. 1, it is not a scaly shape but a shape having a uniform surface as conventionally used. The heating device is driven for about several minutes by the means described in the first to third embodiments, and the release layer 118 of the fixing roller 110 is stretched in a scaly shape.

  In the configuration of the present invention described in the first embodiment, even if it takes several minutes to deform the release layer 118 into a scale shape, as described above, there is an effect of preventing scratches. Serious flaws that cause image defects such as streaks do not occur on the fixing roller 110.

  However, in order to obtain a further effect of preventing scratches and repairing, it is preferable that the release layer 118 of the fixing roller 110 that has been stretched in advance in a scaly manner is incorporated into a fixing device.

  That is, at the manufacturing stage of the fixing roller 110, the release layer 118 is stretched and deformed in a scale shape as shown in FIG. 5 (2) by a method using the means described in the first embodiment.

  If the release layer 118 is deformed in a scaly shape from the initial stage, as described in the first embodiment, even if a foreign matter is mixed into the contact portion N1 and the surface layer of the fixing roller 110 is scraped, the scaly unevenness However, the scratches are only intermittent and do not lead to deep scratches. Further, even if a scratch occurs, the release layer 118 is deformed in a scaly shape. Therefore, the scaly release layer 118 immediately covers the wound by the means used in Example 1 and the like. Can be repaired.

  In this way, if the release layer of the rotating body for image heating has a scale-like release layer stretched in the crossing direction intersecting the rotation direction of the rotating body, it takes time to repair the wound. Time can be shortened.

(Other examples)
In the first to second embodiments described above, the fixing member is used like the sliding member 112, but the present invention is not limited to this. For example, a rotatable sliding member may be used. It is sufficient that the rotatable sliding member is not completely driven with respect to the fixing roller 110. Regardless of the forward direction or counter direction, the temperature of the contact surface with respect to the surface of the fixing roller 110 is maintained at a temperature equal to or higher than the glass transition point of the release layer, and the fixing roller 110 slides on the surface of the fixing roller 110. The effect of the invention is not impaired as long as the roller 110 surface is subjected to frictional force and temperature in the longitudinal direction as well as the circumferential direction. That is, it goes without saying that the rotatable sliding member may be fixed or have a peripheral speed difference with respect to the fixing roller 110.

  In the present embodiment, the sliding member 112 is provided on the entire longitudinal surface. However, the effect of the invention is not impaired even if the sliding member 112 is provided only on the longitudinal portion corresponding to the place where the scratch is likely to occur.

  In addition, the prevention and repair of flaws on the fixing roller have been described. In addition to the fixing member that comes into contact with the toner image, the fixing can be performed even if the present invention is applied to a fixing method using a fixing belt or a film. Similar to the first embodiment, scratch prevention and repair effects can be obtained on the member surface. Further, although the pressure roller is used as the pressure member for forming the fixing nip portion N2, the pressure member is not limited to the roller, and a non-rotating pad member may be used.

  In the above embodiments, the fixing device mounted on the image forming apparatus has been described as an example. However, the image heating apparatus of the present invention is not limited to the fixing device mounted on the image forming apparatus. For example, the technical idea of the present invention can be applied to a gloss applying device that is sold as an option in order to reheat the image fixed by the fixing device in order to improve the glossiness of the image.

FIG. 3 is a conceptual diagram of a fixing device in Embodiment 1. 1 is a schematic front view of a fixing device in Embodiment 1. FIG. FIG. 3 is a schematic front view of the fixing device according to the first exemplary embodiment (rotating a slide cam by 180 °). FIG. 3 is a diagram of the fixing device as viewed from above in the first embodiment. 2 is a photograph of an observation of the surface layer of a new fixing roller and the surface layer of the fixing roller after driving in Example 1. FIG. 2 is an observation view and a photograph of a cross section near the surface layer of a new fixing roller and a cross section near the surface layer of the fixing roller after driving in Example 1. FIG. Figure and observation photograph of the surface layer in the case of only rotation and the combination of rotation and reciprocation of the fixing roller. FIG. 6 is a diagram illustrating a printing durability test result in Example 1. FIG. 6 is a schematic cross-sectional view of a fixing device that moves a sliding member 112 that is a modification of the first embodiment. The figure which shows the example at the time of making the axial direction of a sliding member and a fixing roller into non-parallel. The surface angle histogram which shows the surface property of a fixing roller by the frequency distribution of surface angle. FIG. 2 is a cross-sectional view illustrating the outline of the entire image forming apparatus.

Explanation of symbols

100 Fixing device (image heating device)
110 Fixing roller (rotating body)
111 Pressure roller (backup member)
112 Sliding member 118 Release layer 120 Sliding layer 126 Halogen heater

Claims (3)

In an image heating apparatus comprising: a rotating body having a release layer on a surface; a heating unit that heats the rotating body; and a backup member that forms a nip portion that sandwiches and conveys a recording material that carries an image together with the rotating body. ,
An image heating apparatus, comprising: a sliding member that contacts a surface of the rotating body and extends the release layer in a crossing direction intersecting a rotation direction of the rotating body to deform the scale-like shape.   When the rotating body rotates while being heated by the heating means, at least one of the rotating body and the sliding member moves in the intersecting direction, whereby the release layer is stretched in the intersecting direction. The image heating apparatus according to claim 1.   In a rotating body for image heating used as a rotating body in contact with an image on a recording material of an image heating apparatus that heats an image on the recording material while sandwiching and conveying a recording material carrying an image, the rotation direction of the rotating body A rotating body for heating an image, characterized by having a scale-like release layer stretched in a crossing direction intersecting with respect to.

Images