JP2013167664A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus including a fixation device capable of improving separability even when a separation device gives less influence on a fixation member making use of a relation between surface nature and the separability of the fixation member.SOLUTION: An image forming apparatus (100) comprises: an image heating member (53) for heating an image formed on a recording material (P); and a rubbing member (55) for contacting with a surface of the image heating member, and rubbing the image heating member. The image forming apparatus also includes: an execution part (37) for executing a mode for rubbing the image heating member by the rubbing member in a period between a signal input of an image formation job for forming the image on the recording material and a start of the image formation job; and switching means (141). The switching means switches rubbing conditions in the mode when a basis weight of a recording material selected in the image formation job is a first basis weight, so as to make the surface of the image heating member (53) coarser than when the basis weight of the selected recording material is a second basis weight larger than the first basis weight.

Description

  The present invention relates to an image forming apparatus that forms an image on a recording material using an electrophotographic system such as a printer, a copying machine, a facsimile machine, or a multifunction machine of these.

  In an image forming apparatus using an electrophotographic system, generally, a toner image is formed on an image carrier such as a photosensitive drum or an intermediate transfer member by a toner image forming unit including a charging device, an exposure device, a developing device, and the like. This toner image is transferred onto a recording material such as paper by a transfer means and fixed by a fixing device.

  Generally, in a fixing device, a fixing nip portion is formed by a fixing member such as a fixing roller or a fixing belt that is controlled by heating, and a pressing member such as a pressure roller facing the fixing member, and a toner image is carried on the fixing nip portion. The recording material is nipped and conveyed, and a fixed image is obtained by heat and pressure.

  In such a fixing apparatus, in order to separate the recording material from the fixing member, Patent Document 1 discloses a sheet metal (hereinafter referred to as “separation sheet metal”) close to the position where the separation member does not contact the fixing claw. ) Is described. In order to further improve the separability with respect to the structure of the separation sheet metal, Patent Document 2 describes a structure in which air is blown to separate the recording material from the fixing member.

Japanese Patent No. 4241476 JP 2007-178732 A

  However, in recent years, in order to cope with the diversification of recording materials, further improvement in separation from the fixing member is required. At that time, if the air blowing amount is increased too much in order to improve the separability only by the configuration in which air is blown as in Patent Document 2, temperature unevenness on the fixing member may be increased, which is not preferable.

  Therefore, in the present invention, an image forming apparatus having a fixing device capable of improving the separation property even if the influence of the separation device on the fixing member is reduced by paying attention to the relationship between the surface property and the separation property of the fixing member. The purpose is to provide.

  The present invention includes an image heating member for heating an image formed on a recording material, and a rubbing member for contacting the surface of the image heating member and rubbing the image heating member. In the apparatus, an execution unit that executes a mode in which the rubbing member rubs the image heating member from the input of an image forming job signal for forming an image on a recording material to the start of the image forming job; and the image forming When the basis weight of the recording material selected in the job is the first basis weight, the surface roughness of the image heating member is larger than when the selected recording material is the second basis weight, which is a basis weight larger than the first basis weight. The image forming apparatus includes switching means for switching the rubbing condition in the mode so that the length is increased.

  The present invention also includes an image heating member for heating an image formed on a recording material, and a rubbing member for contacting the surface of the image heating member and rubbing the image heating member. An execution unit that executes a mode in which the rubbing member rubs the image heating member from the input of an image forming job signal for forming an image on a recording material to the start of the image forming job in the forming apparatus; When the thickness of the recording material selected in the forming job is the first thickness, the surface roughness of the image heating member is larger than when the selected recording material is the second thickness which is larger than the first thickness. As described above, the image forming apparatus includes switching means for switching the rubbing condition in the mode.

  According to the present invention, it is possible to improve the separability of various recording materials while reducing the influence of the separating device on the fixing member.

1 is a cross-sectional view of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a block diagram showing a control system of an image forming apparatus common to the first to third embodiments. FIG. 5 is a cross-sectional view showing a fixing device common to the first to third embodiments. 4 is a temperature adjustment table of an image forming apparatus common to the first to third embodiments. The graph which shows the correlation of the surface roughness and the separability for every paper type which concern on 1st-3rd embodiment. The graph which shows the correlation of the surface roughness and glossiness for every paper type which concern on 1st-3rd embodiment. The figure which shows the table of the temperature control and the optimal surface roughness which concern on 1st-3rd embodiment. The graph figure which shows the result of the surface equalization required time from Rz value 1.7 which concerns on 1st Embodiment to 1.0. The graph which shows the result of the Rz value increase time by the rubbing operation | movement at the peripheral speed ratio 150% which concerns on 1st Embodiment. The graph figure which shows the result of Rz value at the time of rubbing for 9 second by each peripheral speed ratio from Rz value 1.4 which concerns on 1st Embodiment. (A) is a schematic diagram of the sliding operation mode transition according to the first to third embodiments, (b) is a diagram showing a friction operation mode content table of the peripheral speed ratio. The flowchart figure which shows the action | operation which concerns on 1st-3rd embodiment. The graph which shows the rubbing roller durability result on the severe conditions in the peripheral speed ratio variable control which concerns on 1st Embodiment. The graph which shows the result of the influence durability to the fixing belt lifetime of the contact pressure which concerns on 2nd, 3rd embodiment. The graph which shows the correlation with the surface roughness and required time in each contact pressure concerning 2nd, 3rd embodiment. The graph which shows the result of the surface equalization required time from Rz value 1.7 to 1.0 in each contact pressure concerning 2nd, 3rd embodiment. The figure which shows the rubbing operation mode content table | surface in the contact pressure which concerns on 2nd Embodiment. The graph which shows the rubbing roller durability result on the severe conditions in the contact pressure variable control which concerns on 2nd Embodiment. The graph which shows the result of the Rz value at the time of rubbing for 9 seconds by contact pressure 1.5kgf in each circumferential speed ratio from Rz value 1.4 which concerns on 3rd Embodiment. The graph figure which shows the rubbing roller durability result on the severe conditions in the combination rubbing control which concerns on 3rd Embodiment. The graph figure which shows the sliding operation mode content table | surface in the contact pressure which concerns on 3rd Embodiment.

  Hereinafter, first to third embodiments according to the present invention will be described with reference to FIGS. FIG. 1 is a side view showing an example of an image forming apparatus 100 equipped with a fixing device 9 to which the present invention is applied, which is common to the first to third embodiments.

  In the following first to third embodiments, a fixing device for fixing an unfixed toner image on a recording material will be described. However, the present invention is configured to heat and press a recording material carrying a fixed image or a semi-fixed image. It can also be implemented as a heat treatment apparatus that adjusts the surface properties of an image.

<First Embodiment>
The first embodiment is generally characterized in that the roughness of the belt surface is changed depending on the speed ratio. The image forming apparatus 100 is a color image forming apparatus using an electrophotographic method. As shown in FIG. 1, in the apparatus main body 100a of the image forming apparatus 100, first, second, third, and fourth image forming units Pa, Pb, Pc, and Pd (hereinafter simply referred to as “image forming unit Pa”). , Pb, Pc, Pd ”). In these image forming portions Pa, Pb, Pc, and Pd, toner images of different colors are formed through the latent image, development, and transfer processes.

  Each of the image forming portions Pa, Pb, Pc, and Pd is provided with a dedicated image carrier, in this example, electrophotographic photosensitive drums 3a, 3b, 3c, and 3d, on the photosensitive drums 3a to 3d. A toner image of each color is formed. An intermediate transfer belt 130 is installed so as to be adjacent to the photosensitive drums 3a to 3d, respectively. The image forming portions Pa to Pd and the intermediate transfer belt 130 constitute an image forming portion that forms a toner image on the recording material. The fixing device 9 fixes the toner image formed on the recording material by the image forming unit to the recording material.

  The toner images of the respective colors formed on the photosensitive drums 3a to 3d are primarily transferred onto the intermediate transfer belt 130, and then transferred onto the sheet-like recording material P at the secondary transfer portion T2. Further, the recording material P to which the toner image has been transferred is fixed to the fixing device 9 by heating and pressing, and then discharged as a recorded image from the apparatus main body 100a by the paper discharge unit 73.

  Drum chargers 2a, 2b, 2c, and 2d, developing devices 1a, 1b, 1c, and 1d, primary transfer chargers 24a, 24b, 24c, and 24d, and cleaners are provided on the outer circumferences of the photosensitive drums 3a to 3d, respectively. 4a, 4b, 4c, 4d are arranged. Further, a light source device (not shown), a polygon mirror, and the like are installed in the upper part of the apparatus main body 100a.

  Laser light emitted from a light source device (not shown) is scanned by a rotating polygon mirror (not shown), the light beam of the scanning light is deflected by a reflecting mirror (not shown), and is sensed by an fθ lens (not shown). The light is condensed and exposed on each bus bar of the body drums 3a, 3b, 3c, and 3d. Accordingly, latent images corresponding to the image signals are formed on the photosensitive drums 3a to 3d, respectively.

  The developing devices 1a, 1b, 1c, and 1d are filled with predetermined amounts of yellow, magenta, cyan, and black toners as developers, respectively, by a supply device (not shown). The developing units 1a, 1b, 1c, and 1d develop the latent images on the photosensitive drums 3a, 3b, 3c, and 3d, respectively, and visualize them as yellow toner images, magenta toner images, cyan toner images, and black toner images.

  The intermediate transfer belt 130 is driven to rotate in the direction indicated by the arrow A in the drawing at substantially the same peripheral speed as the photosensitive drums 3a, 3b, 3c, and 3d. In the image forming apparatus 100 of the present embodiment, for example, the process speed can be set to 380 mm / sec.

  The first color yellow toner image formed and supported on the photosensitive drum 3 a passes through the nip portion between the photosensitive drum 3 a and the intermediate transfer belt 130, and the primary transfer bias is applied to the intermediate transfer belt 130. The intermediate transfer is performed on the outer peripheral surface of the belt by the electric field and pressure formed in step (1).

  Similarly, the magenta toner image of the second color, the cyan toner image of the third color, and the black toner image of the fourth color are successively superimposed and transferred onto the intermediate transfer belt 130 to correspond to the target color image. A composite color toner image is formed.

  The secondary transfer portion T <b> 2 is pressed on the inner surface by the secondary transfer roller 11 and the secondary transfer inner roller 14 at a position facing the secondary transfer roller 11 to form a nip portion between the secondary transfer roller T <b> 2 and the secondary transfer roller 11. And an intermediate transfer belt 130. The secondary transfer roller 11 is pivotally supported in parallel so as to face the intermediate transfer belt 130 whose inner surface is supported by the secondary transfer inner roller 14, and is disposed so as to contact the lower surface portion of the intermediate transfer belt 130. Has been. A desired secondary transfer bias is applied to the secondary transfer roller 11 by a secondary transfer bias source.

  The recording material P is fed from the paper feed cassette 10 by the feeding unit 6, passes through the recording material conveyance unit 7 such as a conveyance roller, the registration roller 12, and a pre-transfer guide (not shown), and then passes through the intermediate transfer belt 130 and the secondary transfer belt 130. It is sent to the contact nip between the transfer rollers 11 at a predetermined timing. At the same time, a secondary transfer bias is applied to the intermediate transfer belt 130 from a bias power source (not shown).

  As a result, the composite color toner image superimposed and transferred onto the intermediate transfer belt 130 is transferred onto the recording material P. That is, the composite color toner image is transferred from the intermediate transfer belt 130 to the recording material P by the secondary transfer bias. The secondary transfer bias at the time of transferring the toner image to the recording material P is opposite in polarity to the toner charge, and depends on the environment (for example, temperature and humidity around the apparatus) and the type of recording material (for example, basis weight, surface property). It is controlled by a control unit 141 described later so as to be optimally set.

  Further, cleaning control of the secondary transfer roller 11 is performed during the interval between continuous paper passing and after the end of the job, and the secondary transfer bias having the same polarity as the toner charge is applied to the secondary transfer roller 11 for a predetermined time. Applied. As a result, the scattered toner and the fog toner adhered to the secondary transfer roller 11 are returned to the intermediate transfer belt 130 side, thereby preventing the transfer performance from being deteriorated and the recording material from being stained.

  The photosensitive drums 3a to 3d that have undergone the primary transfer are cleaned for residual toner by the corresponding cleaners 4a to 4d, respectively, so that they are prepared for the next latent image formation. It should be noted that foreign matters such as toner and paper dust remaining on the intermediate transfer belt 130 are removed by wiping with a cleaning web (nonwoven fabric) 19 in contact with the surface of the intermediate transfer belt 130.

  In the case of the single-sided printing process, the recording material P to which the toner image has been transferred by the secondary transfer unit T2 is sequentially introduced into the fixing device 9 and fixed with the toner image by applying heat and pressure. The output product is discharged out of the apparatus main body 100a through 73. On the other hand, in the case of the double-sided printing process, the recording material P is conveyed to the reversing unit 21, and the front and back are reversed, and then conveyed again to the conveying path 23 via the double-sided conveying path 22, and the secondary transfer portion T2. Then, the toner image on the back surface is transferred, fixed by the fixing device 9, and discharged by the paper discharge unit 73.

  As described above, the image forming apparatus 100 can perform continuous printing by repeating the operations of the paper feeding process, the image forming process, the transfer process, the fixing process, and the paper discharge process. For example, 80 sheets can be output every minute.

  As shown in FIGS. 1 and 2, the image forming apparatus 100 includes a control unit 141 typified by a CPU and the like, an operation unit 142 serving as an interface for a user to access the image forming apparatus 100, and a storage unit 143. Are arranged.

  The control unit 141 coordinates the operation of the entire image forming apparatus by supervising the command system between the units while monitoring and controlling the operation of each part in the image forming apparatus 100. The controller 141 can control the roughness state of the surface of the fixing belt 53 according to the type of the recording material P by the rubbing roller 55 and determines an optimum rubbing sequence of the rubbing roller 55.

  The fixing belt 53 constitutes an image heating member according to the present invention for heating an image formed on the recording material P. The rubbing roller 55 is in contact with the surface of the image heating member and constitutes a rubbing member according to the present invention for rubbing the image heating member. The rubbing roller 55 is configured to change the roughness of the surface of the fixing belt 53 by rubbing the surface of the fixing belt 53 and to rotate independently of the fixing belt 53.

  As shown in FIG. 2, the operation unit 142, the storage unit 143, the image forming units Pa to Pd, the recording material transport unit 7, the fixing device 9, and the like are connected to the control unit 141. The fixing device 9 includes a fixing belt heater 205, a pressure roller pressure separation motor 201, a rubbing roller pressure separation motor 202, a fixing roller driving device 203, and a rubbing roller driving device 204.

  When the basis weight of the recording material P selected in the image forming job is the first basis weight, the control unit 141 has a larger surface roughness of the fixing belt 53 than when the selected recording material is the second basis weight. Thus, the switching means of the present invention is configured to switch the rubbing condition in the mode. The second basis weight means a basis weight larger than the first basis weight.

  The control unit (switching unit) 141 is a mode (sliding mode) that is executed according to the mode (rubbing operation mode) that was previously executed and stored in the storage unit 143 and the image forming job that is input by the operation of the operation unit 142. The rubbing condition is determined by comparing with the rubbing operation mode. The controller 141 changes the rubbing state of the rubbing roller 55 against the fixing belt 53 by changing the peripheral speed ratio between the rubbing roller 55 and the fixing belt 53.

  The operation unit 142 allows the user to perform basic setting of print job information (recording material information such as basis weight, image information such as density, print information such as the number of prints), and continuously switching the recording material type. Detailed settings such as so-called “mixed jobs” can be made.

  The storage unit 143 stores the previously executed mode (rubbing operation mode). A rubbing mechanism 37 described below is a mode (rubbing operation mode) in which the rubbing roller 55 rubs the fixing belt 53 from the input of an image forming job signal for forming an image on a recording material to the start of the image forming job. The execution unit of the present invention is executed.

  In this case, the circumferential speed ratio between the fixing belt 53 and the rubbing roller 55 when the basis weight of the recording material selected in the image forming job is the first basis weight is such that the selected recording material is more than the first basis weight. It is larger than the peripheral speed ratio between the fixing belt 53 and the rubbing roller 55 when the second basis weight is a large basis weight.

  Next, with reference to FIG. 3, the fixing device 9 which is the image heating device of the present invention will be described. FIG. 3 is a cross-sectional view illustrating a schematic configuration of the fixing device 9.

  As shown in FIG. 3, the fixing device 9 constitutes an image heating device that heats a toner image on a recording material passing through a fixing nip portion (nip portion) N by a fixing belt 53 that is an image heating member. . In the fixing device 9, the fixing roller 51 and the support roller 54 are driven while stretching the endless fixing belt 53, and the fixing roller 51 is pressed by the pressure roller 52 so as to sandwich the fixing belt 53. The fixing nip portion N is formed. The recording material P passes from the right to the left in the drawing, and is heated and pressurized at the fixing nip N, whereby the toner image is fixed.

  A pressure control mechanism 38 that controls the pressure state of the pressure roller 52 is disposed below the support portion 30 on the apparatus main body side of the fixing device 9. In the pressurization control mechanism 38, the arm member 26 is supported at one end portion thereof so as to be rotatable by the support shaft 27. A cam member 29 is rotatably supported by the support portion 30, and the other end portion of the arm member 26 is in contact with the cam member 29. A rod-like support member 25 is slidably penetrated through a substantially central portion of the arm member 26. The front end of the support member 25 extends toward the rotation shaft 52 a that protrudes from both ends of the pressure roller 52. The compression spring 28 fitted into the support member 25 has one end abutting against the arm member 26 and the other end abutting against the rotating shaft 52 a of the pressure roller 52.

  With this structure, when the cam member 29 is rotated by the driving of the pressure roller pressurizing / separating motor 201, the arm member 26 is rotated by the rotation shaft 52a of the pressure roller 52 via the compression spring 28 based on a predetermined cam shape. Press or release. As a result, the pressure applied to the fixing belt 53 by the pressure roller 52 can be adjusted to adjust the area of the fixing nip portion N. During image formation, the control unit 141 performs control so as to form a fixing nip portion N by, for example, applying a total pressure of 500 N, and controls to stand by in a separated state during jam processing or during warm-up. .

  Further, a rubbing mechanism (execution unit) 37 having a rubbing roller 55 is disposed on the upper side of the support unit 30. In the rubbing mechanism 37, one end of the arm member 32 is supported by the support shaft 33 so as to be rotatable. A cam member 35 is rotatably supported by the support portion 30, and the other end portion of the arm member 32 is in contact with the cam member 35.

  A rod-like support member 34 is slidably passed through the substantially central portion of the arm member 32. The front end of the support member 34 extends toward the rotation shaft 55 a that protrudes from both ends of the rubbing roller 55. A compression spring 31 such as a coil spring is fitted into the support member 34. The compression spring 31 has one end abutted on the arm member 32 and the other end abutted on the rotating shaft 55a of the rubbing roller 55. ing.

  With this structure, when the cam member 35 is rotated by the driving of the rubbing roller pressurizing / separating motor 202, the arm member 32 is rotated by the rotation shaft 55a of the rubbing roller 55 via the compression spring 31 based on a predetermined cam shape. Press or release. Thereby, the pressure applied to the fixing belt 53 by the rubbing roller 55 can be adjusted and adjusted. The shape of the cam member 29 and the cam member 35 described above can be, for example, an elliptical shape in which the center of rotation is eccentric.

  The fixing roller 51 is heated from the inner surface side and the surface side comes into contact with the recording material P via the fixing belt 53 and is rotatably supported by a fixing portion (not shown) of the fixing device 9. The fixing roller 51 has a central core of φ18.5 / end φ16.0 on an Fe cored bar having an arc-shaped crown shape and a rubber hardness of 15 ° with a center of 0.75 mm and an end of 2 mm. A silicone rubber elastic layer (JIS-A 1 kg load) is held. The outer diameter of this roller has a straight shape of φ20 throughout.

  The reason why the metal core is formed in a longitudinal crown shape is to prevent the central pressure drop when the fixing nip portion N is formed, and the reason why the roller outer diameter is straight is to drive the fixing belt 53 stably. The rotation shafts 51 a at both ends of the fixing roller 51 are rotatably held on the side plates of the fixing device 9. In this embodiment, the fixing belt 53 constitutes the image heating member. However, for example, the fixing belt 53 can be eliminated and the fixing roller 51 itself can be used as the image heating member. The fixing roller 51 is directly rubbed at 55.

  The pressure roller 52 constitutes a rotatable pressure member that presses the fixing belt 53 to form the fixing nip portion N, and is disposed on the back side of the surface of the recording material P on which the unfixed toner image is formed. And is supported so as to be rotatable in one direction (the direction of the arrow). The pressure roller 52 is rotatably supported by a fixing portion (not shown) of the apparatus main body 100 a, and the rotation shaft 52 a is disposed so as to be parallel to the rotation shaft 51 a of the fixing roller 51. The pressure roller 52 holds a 1.0 mm thick silicone rubber elastic layer having a uniform rubber hardness of 20 ° (JIS-A 1 kg load) on a straight-shaped Fe cylindrical core metal having an outer diameter of φ18 mm, and is separated at the top. A PFA tube having a thickness of 30 μm is coated as a mold layer.

  The pressure roller 52 may or may not have a heating source inside the cored bar. In this embodiment, the roller-type pressure roller 52 is used as the pressure member. However, if the pressure member can press the fixing belt 53 to form the fixing nip portion N, a belt-type pressing roller 52 is used. A pressure member may be employed.

  As the fixing belt 53 of this embodiment, for example, a Ni base layer having an inner peripheral length of 157 mm and a thickness of 60 μm and a silicone rubber elastic layer having a thickness of 300 μm and a rubber hardness of 23 ° (ASKER-C 1 kg load) is used. be able to. Then, for example, a PFA tube having a thickness of 40 μm can be coated on the elastic layer.

  For example, an Fe pipe having an outer diameter of φ18 and a thickness of 1 mm is used for the support roller 54 that forms a pair with the fixing roller 51 and stretches the fixing belt 53. A fixing belt heater 205 composed of a halogen heater is provided. The controller 141 controls the temperature of the fixing belt 53 by a temperature detection member 36 such as a thermistor disposed on the inner surface of the fixing belt 53 to a predetermined target temperature corresponding to the paper type. Further, as another heating means, an electromagnetic induction heating means having a configuration in which an exciting coil is arranged on the outer peripheral portion of the fixing belt 53 may be used.

  Here, a detailed configuration of the rubbing roller 55 in the rubbing mechanism 37 will be described. That is, as shown in FIG. 3, the rubbing roller 55 has a pressure roller 52 sandwiched between the fixing roller 51 in order to avoid interference with upstream and downstream conveying members (see FIG. 1) of the fixing nip N. Located on the opposite side. In the present embodiment, for example, a structure in which an aluminum oxide-based abrasive is bonded to the surface of a SUS roller having a central outer diameter φ12 is used.

  As other materials (rubbing materials) for the rubbing roller 55, silicon oxide, titanium oxide, iron oxide, chromium oxide, or the like can be used, or these compounds can be used instead. In each of the following embodiments including this embodiment, the ten-point average roughness Rz according to Japanese Industrial Standard JIS B0601-1994 is used as the surface roughness of the rubbing roller 55.

  In the present embodiment, it is preferable that the surface roughness of the rubbing roller 55 is a ten-point average roughness Rz of about 15 to 20 μm. If the surface roughness of the rubbing roller 55 is rougher than this value, the surface of the fixing belt 53 may be deeply damaged, which is not preferable if the image at the time of fixing is affected. The effect of the rubbing roller 55 is that the rubbing roller 55 is brought into pressure contact with the fixing belt 53 with a predetermined pressure and driven with a peripheral speed ratio (peripheral speed ratio), which will be described later. Can be attached to the surface layer of the fixing belt to form a surface having good separability.

  The controller 141 controls the pressure control mechanism 38 so as to pressurize the pressure roller 52 even when performing a rubbing operation. Similarly, the controller 141 also controls the rubbing roller pressurizing / separating motor 202 for the rubbing mechanism 37 so that the rubbing roller 55 is pressed against or separated from the surface of the fixing belt 53 (contacting / separating operation). To control.

  In this embodiment, the contact pressure (rubbing roller pressure) of the rubbing roller 55 with respect to the fixing belt 53 can be set to a load value of 0.5 kgf (≈4.903 N), for example. In this embodiment, the reason why the rubbing roller 55 is not always in contact with the fixing belt 53 is to achieve both the effect of stabilizing the image quality and the durability of the fixing belt 53 and the rubbing roller 55. . Further, the fixing roller driving device 203 and the rubbing roller driving device 204 are configured to be independently driven and controlled by different motors.

  In the present embodiment, as described above, the ten-point average roughness Rz (μm) is used as the surface roughness parameter of the fixing belt 53 (hereinafter, “μm” may be omitted). The ten-point average roughness Rz of the initial surface roughness of the fixing belt 53 in this embodiment can be set to about 0.4 μm, for example.

Hereinafter, the optimum value of the ten-point average roughness Rz in each condition in the fixing device 9 is determined. FIG. 4 is a view showing a temperature adjustment table regarding the basis weight (g / m ² ), the set target temperature (° C.), and the surface temperature (° C.) of the fixing belt 53 for the corresponding paper type in the image forming apparatus 100 according to the present invention. is there.

  The table in FIG. 4 is set in consideration of a temperature range that achieves both separation performance and fixing performance for each paper type in the fixing device 9. During each paper type classification, the results of the experiment (the separation and fixability experiments for each paper type are not described), using the paper with the most severe separation for each as the recording material, the separable temperature and the ten-point average roughness Rz Sought a relationship with.

In the table of FIG. 4, for thin paper and recycled paper, the basis weight is set to 52 to 75 g / m ² , the set target temperature is set to 155 ° C., and the surface temperature of the fixing belt 53 is set to 150 ° C. For plain paper, the basis weight is set to 76 to 180 g / m ² , the set target temperature is set to 175 ° C., and the surface temperature of the fixing belt 53 is set to 170 ° C. Further, for the coated paper, the basis weight is set to 106 to 180 g / m ² , the set target temperature is set to 195 ° C., and the surface temperature of the fixing belt 53 is set to 189 ° C.

The basis weight (g / m ² ) is a way of expressing the weight of the recording material such as paper, and represents the weight of the recording material per area of 1 m ^{2. The} heavier the recording material, the more the recording material becomes. Since the thickness tends to increase, the basis weight can be used in the same meaning as “the thickness of the recording material”. That is, in the present embodiment, the table switches the paper type according to the basis weight, but the same configuration as the present invention can be obtained by using a table that switches the paper type according to the thickness instead of the basis weight.

  Accordingly, the control unit 141 causes the surface roughness of the fixing belt 53 to be greater when the thickness of the recording material selected in the image forming job is the first thickness than when the thickness of the selected recording material is the second thickness. The switching means of the present invention for switching the rubbing condition in the mode (rubbing operation mode) is also configured. The second thickness means a thickness larger than the first thickness.

  In addition, the control unit 141 compares the previously executed mode stored in the storage unit 143 with the mode executed according to the image forming job input by the operation of the operation unit 142, and sets the rubbing condition. decide.

  In this case, the circumferential speed ratio between the fixing belt 53 and the rubbing roller 55 when the thickness of the recording material P selected in the image forming job is the first thickness is such that the selected recording material is larger than the first thickness. It is larger than the peripheral speed ratio between the fixing belt 53 and the rubbing roller 55 at the second thickness.

  Next, the correlation between the separable temperature and the surface roughness for each paper type will be described with reference to FIG. The horizontal axis in the graph of FIG. 5 indicates the ten-point average roughness Rz of the surface of the fixing belt 53. The graph is obtained by measuring the separability in such a state that the rubbing roller 55 is brought into pressure contact with the fixing belt 53 and roughened in advance so as to obtain each level of Rz. The surface roughness is measured using a surface roughness measuring instrument SE-3400 (conditions: feed rate 0.5 mm / s, cut-off 0.8 mm, measurement length 2.5 mm) manufactured by Kosaka Laboratory. I went there.

In FIG. 5, the ten-point average roughness Rz of the fixing belt 53 is assigned to several levels. At that time, thin paper / recycled paper (indicated by “●”, basis weight 67 g / m ² ) and plain paper ( It is shown as x by C. The basis temperature is 81 g / m ² ), and the temperature at which separation is possible in coated paper (referred to as O and indicated by ▲. Basis weight 128 g / m ² ) is shown by experiments. In this experiment, the upper limit of the set temperature adjustment was 215 ° C.

  When the result of FIG. 5 is seen, the coated paper O indicated by ▲ does not cause a separation failure in each of the ten-point average roughness Rz, and the plain paper C indicated by × increases as the ten-point average roughness Rz increases. The separability tends to be slightly improved.

  On the other hand, it can be seen that the thin paper / recycled paper G indicated by ● has the greatest change, and the separability is drastically improved with the 10-point average roughness Rz being around 1.5 μm as a boundary. For plain paper C and coated paper O, a margin of 10 ° C. or more can be expected at each Rz for the separable temperature with respect to the set temperature adjustment, whereas for thin paper / recycled paper G, Rz1.5 must not be around. It can be seen that a sufficient margin from the separable temperature cannot be obtained.

  From the above results, it was found that the thin paper / recycled paper G indicated by ● has the highest separation performance with respect to the set temperature, and the Rz sensitivity in separation performance is large. Therefore, when passing thin paper / recycled paper, it is desirable that the ten-point average roughness Rz of the surface of the fixing belt 53 is roughened to 1.5 μm or more and less than 2.0 μm. This is because when the roughness is greater than Rz 2.0 or more, the glossiness of the image after fixing is greatly reduced. Accordingly, as the Rz optimum value for thin paper / recycled paper, the use of Rz1.7, which is stable and high in separable temperature with respect to the ten-point average roughness Rz, does not occur.

  Further, the plain paper C indicated by “X” and the coated paper O indicated by “▲” have sufficient separability when the ten-point average roughness Rz is in the range of 0.5 to 1.7.

  Since the vertical axis temperature in FIG. 5 is highly separable and sensitive to the surface temperature of the fixing member, the surface temperature of the fixing belt 53 was measured using a contact-type surface temperature measuring device. Here, when the temperature difference between the inner surface temperature of the fixing belt and the surface temperature was measured in each temperature range, the surface was lower by about 5 ° C. than the inner surface. Therefore, for example, when the set temperature adjustment is 155 ° C., the surface temperature is about 150 ° C.

  Next, the relationship between the image quality of the fixed image and the ten-point average roughness Rz will be described. Generally, when the surface of the fixing member is rough, the glossiness of the image after fixing is lowered, or uneven glossiness is generated in the surface.

  FIG. 6 is a diagram showing the relationship between the measured value of the glossiness of the fixed image used in the separation experiment and Rz at that time.

  From the results shown in the figure, the sensitivity of the ten-point average roughness Rz in the glossiness of the plain paper C indicated by x and the thin paper / recycled paper G indicated by ● is low, whereas the coated paper O indicated by ▲ is Rz1. It can be seen that the glossiness suddenly decreases from 0 to 1.7. In addition, thin paper / recycled paper and plain paper are not necessarily required to have high gloss, whereas coated paper needs to have high gloss in view of market usage trends.

  From the above results, 90% or more of the glossiness of the image after fixing with the set temperature adjustment in Rz0.4 (in a state where the surface is not roughened) on the coated paper is set as the allowable range. For that purpose, Rz of 1.2 or less is required, and further Rz of 1.0 or less is desired in order to obtain high gloss stably.

  There is no particular problem if the glossiness is 10 or more for thin paper and recycled paper, and 15 or more for plain paper. However, if the average roughness Rz2.0 exceeds 10 points as described above, an image quality defect occurs. If it is 1.7 or less, there is no particular problem. The measuring method of glossiness used the Nippon Denshoku Industries Co., Ltd. handy type gloss meter (PG-1M) (based on JISZ8741 specular glossiness-measuring method). The measured value by this measuring method is given in%.

  As described above, the optimum Rz value for each paper type group in the fixing device 9 of this embodiment is 1.7 for thin paper / recycled paper G, 1.7 or less for plain paper C, and 1.0 or less for coated paper O. I found out.

  Since the Rz optimum value has been determined from the above experimental results, the rubbing method by the rubbing roller 55 in the rubbing mechanism 37 as a means for setting the Rz of the fixing belt 53 to the Rz optimum value will be described in detail below. To do.

  When the change of Rz on the surface of the fixing belt 53 is instructed, the control unit 141 presses the rubbing roller 55 against the fixing belt 53 so that the Rz on the surface of the fixing belt 53 has a desired value. Control is made so that the roller 55 is driven. Here, when the rubbing roller 55 is not driven, it follows the fixing belt 53, and the rubbing is performed with the smallest rubbing force in the present embodiment.

  Note that the direction of rotation when driving the rubbing roller 55 is the direction along the rotation of the fixing belt 53 (that is, the counterclockwise direction in FIG. 3), and the direction against the rotation of the fixing belt 53 (that is, the clockwise direction in FIG. 3). However, in this embodiment, the direction is along the rotation of the fixing belt 53. The same applies to a third embodiment described later.

  In this embodiment, the peripheral speed ratio is changed by changing the peripheral speed of the rubbing roller 55 with respect to the fixing belt 53 that rotates normally, but the fixing is performed with respect to the rubbing roller 55 that rotates at a constant peripheral speed. It is also possible to change the peripheral speed ratio by changing the peripheral speed of the belt 53. It is also possible to change the peripheral speed ratio by changing the peripheral speeds of both the rubbing roller 55 and the fixing belt 53.

Here, assuming that the peripheral speed of the fixing belt 53 is v and the peripheral speed of the rubbing roller 55 is v ′, the rubbing roller 55 is driven,
v '> v or v'<v
Then, the peripheral speed ratio is added, and the value of the ten-point average roughness Rz increases or decreases. Peripheral speed ratio is
100 × (| v′−v | + v) / v
Represented by
v = v '
At that time, it was set to 100%.

  Here, when the peripheral speed ratio is increased, the ten-point average roughness Rz is also increased. Further, when the ten-point average roughness Rz is somewhat large, the ten-point average roughness Rz can be decreased to a certain degree by rubbing with the peripheral speed ratio being reduced. This is because the surface of the fixing belt 53 that is greatly roughened is smoothed (smoothed) so as to be leveled (equalized) by eliminating the difference in surface roughness.

  Next, in order to incorporate the above-described rubbing operation into actual control, the relationship between the peripheral speed ratio between the fixing roller 51 and the fixing belt 53 and the ten-point average roughness Rz is obtained. It is necessary to set the rubbing time. The time for performing the rubbing operation is preferably within the waiting time required for switching the paper type. FIG. 7 is a table in which the paper type switching required time in the fixing device 9 and the optimum Rz value in each paper type group are added to the table in FIG.

  From the table of FIG. 7, each mode for increasing / decreasing the ten-point average roughness Rz is extracted, and a peripheral speed ratio at which the transition of the Rz value can be achieved within the required time of the mode is set. The reason why the coated paper is set to Rz 1.0 in FIG. 7 is as follows. The first reason is that there is no problem in image quality (glossiness). The second reason is that the surface of the fixing belt 53 that has been rubbed once and roughened to about Rz1.7 has a ten-point average roughness Rz of 0.9 even if the surface speed is reduced by reducing the peripheral speed ratio. It is mentioned that it returns only to about -1.0.

  Next, the reason why the plain paper is Rz1.4 will be described below. FIG. 8 shows the time of the ten-point average roughness Rz when the ten-point average roughness Rz on the surface of the fixing belt 53 is rubbed and averaged at a peripheral speed ratio of 100% from the state of 1.7 μm to 1.0 μm. It is a graph which shows a change.

  As can be seen from FIG. 8, it takes about 22 seconds to change from Rz 1.7 μm to Rz 1.0 μm. If plain paper is selected from thin paper / recycled paper, and then a mixed-load job in which coated paper is selected is selected, if Rz is not changed from thin paper / recycled paper to plain paper, plain paper to coated paper is used. When switching to, a rubbing time of 22 seconds is required.

  Referring to FIG. 7, the paper type switching time from plain paper to coated paper is 20-9 = 11 (seconds) in the “time required for temperature rise” table in FIG. Extra waiting time will occur. Therefore, in order to alleviate this problem, the optimum value of the ten-point average roughness Rz for plain paper is set to 1.4. This value satisfies both the separation property and image quality of plain paper, and as can be seen from FIG. 8, it is possible to smoothly connect the time required for the mixed loading job and the time required for Rz transition (still 1 second). Some waiting time will occur).

  Next, a mode for increasing the ten-point average roughness Rz on the surface of the fixing belt 53 will be described. FIG. 9 is a diagram showing the change over time of the increase in Rz when the surface of the fixing belt 53 having a ten-point average roughness Rz of 1.0 μm is rubbed and roughened at a peripheral speed ratio of 150%.

  From the slope of FIG. 9, when rubbing from a state where the ten-point average roughness Rz is small (for example, Rz 1.0 μm), the Rz increase rate is large in the beginning, but the Rz increase rate becomes dull when roughened to some extent. I understand that

  From the above, it can be seen that the strict condition in the mode in which the ten-point average roughness Rz is increased is the case of transition from plain paper to thin paper / recycled paper (Rz 1.4 to 1.7 in 11 seconds). . Here, considering that the pressure-bonding operation of the rubbing roller 55 takes about 1.5 seconds, it is desirable to complete the mode within about 9 seconds. Therefore, the peripheral speed ratio is varied, and the fixing belt 53 having a 10-point average roughness Rz of 1.4 μm on the surface is rubbed for 9 seconds, and the peripheral speed ratio satisfying the above condition (Rz 1.4 to 1.7 μm) is satisfied. The required experiment was performed (see FIG. 10).

  FIG. 10 is a graph showing the result of the Rz value when the fixing belt 53 is rubbed for 9 seconds using each peripheral speed ratio from the Rz value 1.4 in the present embodiment. From the graph, it was shown in the experimental results that the Rz increase mode can be applied to all modes at a peripheral speed ratio of 100 to 170%.

  Further, in this experiment, when the rubbing operation to the fixing belt 53 was performed at a peripheral speed ratio of 200% or more, a small but not negligible image quality defect (fine and small sharp scratch) occurred in the fixed image. As described above, it was confirmed that the above-described adverse effects occur when the peripheral speed ratio is excessively increased.

  Next, with reference to FIGS. 11A and 11B, the Rz increase / decrease mode in the present embodiment will be described. 11A is a schematic diagram of transition to the rubbing operation mode (respective Rz increase / decrease mode schematic diagram), and FIG. 11B is a rubbing operation with a peripheral speed ratio corresponding to FIG. 11A. It is a figure which shows a mode content table.

  In FIG. 11A, the transition from thin paper / recycled paper to coated paper is shown in the rubbing operation mode (i), and the transition from thin paper / recycled paper to plain paper is shown in the rubbing operation mode (ii). The transition from paper to coated paper is shown in the rubbing operation mode (iii). Furthermore, the transition from coated paper to plain paper is indicated by the rubbing operation mode (iv), and the transition from plain paper to thin paper / recycled paper is indicated by the rubbing operation mode (v), from coated paper to thin paper / recycled paper. This transition is shown in the rubbing operation mode (vi).

  In the table of FIG. 11B, in the rubbing operation mode (i), the ten-point average roughness Rz before rubbing is 1.7 μm, the ten-point average roughness Rz after rubbing is 1.0 μm, and the paper type The time required for the change is 20.0 seconds, the peripheral speed ratio is 100%, and the time required for the rubbing operation is 22.0 seconds. In the rubbing operation mode (ii), the ten-point average roughness Rz before rubbing is 1.7 μm, the ten-point average roughness Rz after rubbing is 1.4 μm, and the time required for changing the paper type is 9.0 seconds. The peripheral speed ratio is 100%, and the time required for the rubbing operation is 10.0 seconds. In the rubbing operation mode (iii), the 10-point average roughness Rz before rubbing is 1.4 μm, the 10-point average roughness Rz after rubbing is 1.0 μm, the paper type change required time is 11.0 seconds, The peripheral speed ratio is 100%, and the time required for the rubbing operation is 12.0 seconds.

  In the rubbing operation mode (iv), the 10-point average roughness Rz before rubbing is 1.0 μm, the 10-point average roughness Rz after rubbing is 1.4 μm, and the paper type change required time is 16.0. Second, the peripheral speed ratio is 150%, and the time required for the rubbing operation is 11.0 seconds. In the rubbing operation mode (v), the 10-point average roughness Rz before rubbing is 1.4 μm, the 10-point average roughness Rz after rubbing is 1.7 μm, and the time required for changing the paper type is 11.0 seconds. The peripheral speed ratio is 170%, and the time required for the rubbing operation is 9.0 seconds. In the rubbing operation mode (vi), the ten-point average roughness Rz before rubbing is 1.0 μm, the ten-point average roughness Rz after rubbing is 1.7 μm, and the time required for changing the paper type is 27.0 seconds. The peripheral speed ratio is 155%, and the time required for the rubbing operation is 25.0 seconds.

  Next, specific control of the rubbing operation will be described with reference to the flowchart of FIG. In this flowchart, T indicates the history variable of the paper type that was passed last time, and N indicates the selected paper type variable. 1-3 are paper type numbers, 1 is thin paper / recycled paper, 2 is plain paper, and 3 is coated paper. Further, (i) to (vi) indicate the rubbing operation mode, and reference is made to FIGS. 11, 17 and 21.

  That is, when a print start job (image forming job) is instructed (print start command), the control unit 141 first determines whether or not there is a rubbing operation history (that is, whether or not the first use is not slid). (Step S1). As a result, when the initial stage has no rubbing operation history (S1: Yes), the initial surface Rz of the fixing belt 53 is about 0.4, so the rubbing roller 55 is pressed against the fixing belt 53. Then, a rubbing operation is performed for 10 seconds at a peripheral speed ratio of 130% (step S2). As a result, the ten-point average roughness Rz of the surface of the fixing belt 53 is roughened to about 1.0 μm. This Rz1.0 is the same state as the optimum ten-point average roughness Rz for coated paper. Therefore, the previous paper passing history variable T is set to 3 for coated paper (step S3).

  Subsequently, according to the paper type selected in the current job (image forming job), one of the paper type numbers 1 to 3 is entered in the selected paper type variable N (steps S4 to S8). That is, in step S4, it is determined whether or not thin paper / recycled paper is selected. As a result, if thin paper / recycled paper is selected (S4: Yes), the process proceeds to step S5, and the selected paper type variable is selected. N is 1 for thin paper and recycled paper.

  If thin paper / recycled paper is not selected in step S4 (S4: No), it is further determined in step S6 whether plain paper is selected. As a result, if plain paper is selected (S6: Yes), the process proceeds to step S7, and the selected paper type variable N is set to 2 for plain paper. On the other hand, if plain paper is not selected in step S6 (S6: No), the process proceeds to step S8, and the selected paper type variable N is set to 3 for coated paper.

  In step S9, it is determined whether or not the same paper type is passed. If T = N (S9: Yes), it means that the same paper type is passed. Printing is started without performing the rubbing operation. On the other hand, if T and N are different in step S9 (S9: No), the process proceeds to a phase of which sliding operation mode is to be applied next.

  From here, it is determined which of the rubbing operation modes (i) to (vi) in FIG. That is, (i)-(vi) is determined by the combination of T and N.

  As an example, when T = 1 and N = 2, the current belt surface Rz is 1.7 because the previous sheet was thin paper / recycled paper. Since the paper type selected this time is plain paper 2, we want to reduce the ten-point average roughness Rz to 1.4 μm. This means that (ii) in FIG. 11 is applied.

  When the rubbing operation mode (ii) is applied, as a specific operation content, as shown in FIG. 11B, a rubbing operation is performed for 10 seconds at a peripheral speed ratio of 100%. Actually, it takes about 1 second by the pressure-bonding operation of the rubbing roller 55, so the entire rubbing operation takes about 11 seconds.

  Then, when each rubbing operation by the rubbing roller 55 is completed, the rubbing roller 55 is put in a detached state, the previous sheet passing history variable T is updated to 2, and printing is started (steps S10 to S26). Here, the removal control of the rubbing roller 55 may be performed up to the release state independently even if it does not end before the start of printing, and does not contribute to an increase in standby time. Similar control is performed in other modes.

  That is, in step S9, it is determined whether or not the paper type is the same as that of the previous time (T = N?). If the paper type is the same as that of the previous time (T = N), the rubbing is performed. Printing is started without performing any operation. On the other hand, if it is determined in step S9 that the paper type is not the same as the previous paper type, the process advances to step S10 to determine whether the previous paper type is thin paper / recycled paper 1 (T = 1?). To do. As a result, if it is determined that the paper type of the previous paper pass is not thin paper / recycled paper 1, the process proceeds to step S16 to determine whether the paper type of the previous paper pass is plain paper 2 (T = 2?). to decide. On the other hand, if it is determined in step S10 that the previous paper type is thin paper / recycled paper 1, the process proceeds to step S11.

  If it is determined in step S16 that the paper type is not the same as the previous time (T ≠ 2), the process proceeds to step S22. If the same paper type is used as the previous time (T = 2), the process proceeds to step S17. It is then determined whether the selected paper type is thin paper / recycled paper 1 (N = 1?).

  If it is determined in step S17 that the selected paper type variable N is thin paper / recycled paper 1 (N = 1) (S17: Yes), the process proceeds to step S18, and the rubbing operation mode (v). In step S19, 1 is entered in the previous paper passing history variable T. On the other hand, if it is determined in step S17 that the selected paper type variable N is not thin paper / recycled paper 1 (N ≠ 1) (S17: No), the process proceeds to step S20 and the rubbing operation mode (iii). In step S21, 3 is entered in the previous paper passing history variable T.

  On the other hand, if it is determined in step S22 that the selected paper type variable N is thin paper / recycled paper 1 (N = 1) (S22: Yes), the process proceeds to step S23, and the rubbing operation mode is performed. (Vi) is executed, and 1 is entered in the previous paper passing history variable T in step S24. On the other hand, if it is determined in step S22 that the selected paper type variable N is not thin paper / recycled paper 1 (N ≠ 1) (S22: No), the process proceeds to step S25 and the rubbing operation mode (iv). In step S26, 2 is entered in the previous paper passing history variable T.

  In step S11, it is determined whether the selected paper type variable N is thin paper / recycled paper 1. As a result, if it is determined that the selected paper type variable N is thin paper / recycled paper 1 (S11: Yes), the process proceeds to step S12 to execute the rubbing operation mode (ii), and in step S13, 2 is added to the previous paper passing history variable T. On the other hand, if it is determined in step S11 that the selected paper type variable N is not thin paper / recycled paper 1 (N ≠ 1) (S11: No), the process proceeds to step S14 and the rubbing operation mode (i). In step S15, 3 is entered in the previous paper passing history variable T.

  Based on the experimental results and control described above, the surface of the fixing belt 53 is appropriately roughened by the rubbing roller 55, so that sufficient improvement in separation of thin paper and recycled paper, which has been a problem, can be achieved without sacrificing image quality. Could be achieved.

  As described above, in this embodiment, the rubbing mechanism 37 as the execution unit causes the rubbing roller 55 to slide the fixing belt 53 between the input of the image forming job signal for forming an image on the recording material and the start of the image forming job. A rubbing mode (rubbing operation mode) is executed. When the basis weight of the recording material selected in the image forming job is the first basis weight (for example, thin paper / recycled paper), the control unit 141 serving as a switching unit switches as follows. That is, the mode (in which the surface roughness of the fixing belt 53 is larger than when the selected recording material has a second basis weight (for example, plain paper, coated paper) having a basis weight larger than the first basis weight). The rubbing condition in the rubbing operation mode) is switched. Alternatively, when the thickness of the recording material selected in the image forming job is the first thickness (for example, thin paper / recycled paper), the control unit 141 as a switching unit performs switching as follows. That is, the rubbing condition in the mode so that the surface roughness of the fixing belt 53 is larger than when the selected recording material is a second thickness (for example, plain paper, coated paper) that is larger than the first thickness. Switch.

  Thereby, the separation state of the recording material P from the fixing belt 53 can be appropriately adjusted. At that time, by changing the rubbing degree for each recording material so as to satisfy the image quality desired for the recording material, and improving the belt surface state optimally, the separation of thin paper and recycled paper is improved without degrading the image quality. It became possible to make it. Accordingly, even when a recording material that requires the next high image quality is selected while appropriately adjusting the contact area between the surface of the fixing belt 53 and the recording material P by adjusting the rough state of the surface of the fixing belt 53, it is desirable. Can achieve gloss and the like.

  For this reason, even thin paper / recycled paper with low stiffness can be easily peeled off, so that the separation failure of the recording material P from the fixing belt 53 can be effectively performed without using a separation claw, separation sheet metal, or compressed gas. Can be resolved. As described above, according to this embodiment, it is possible to improve the separability of various recording materials while reducing the influence of the separating device on the fixing member (fixing belt 53). That is, the surface of the fixing belt 53 is modified by the rubbing roller 55 according to the type of the recording material P, and the image quality is lowered by changing the degree of rubbing to obtain the optimum surface state of the fixing belt 53. Therefore, it is possible to improve the separation between thin paper and recycled paper.

  Here, as a point newly required when the rubbing operation is performed, the life of the rubbing roller 55 is cited. FIG. 13 shows the case where the rubbing roller 55 in the present embodiment is considered to have the most severe durability, in which the rubbing operation modes (ii) and (v) in FIG. It is a graph showing the rubbing life of the rubbing roller 55 when the peripheral speed ratio is fixed to 100% in the same mode. The paper size used is A4 landscape feed.

  In the graph, the horizontal axis indicates the number of durable sheets, and the vertical axis indicates that (ii) and (v) are taken out once 100 sets have passed and another fixing device (with the same configuration on the surface of the fixing belt). Rz is a value of Rz when it is placed on a surface having Rz of 1.0 and rubbed for a predetermined time. In this experiment, if the rubbing roller 55 is in the initial stage, the belt surface Rz value after rubbing is set to 1.7, and the rubbing ability when the durability progresses is measured.

  From FIG. 5, if the ten-point average roughness Rz is less than 1.3 μm, it is considered that sufficient separability, which is the object of the present invention, cannot be secured, and is defined as the life of the rubbing roller 55 at that time. Looking at the experimental results shown in FIG. 13, in the mode in which the peripheral speed ratio is not fixed at 100%, about 110,000 sheets were durable, whereas in the mode in which the ratio was fixed at 100%, the durable life was reached at about 40000 sheets.

  The reason for the difference in the service life is that the rubbing operation with the peripheral speed ratio causes belt adhering, rubbing roller surface contamination due to hoisting of the shavings, abrasive material wear, chipping, peeling, etc. This is thought to be easy to occur. From the above, an improvement in the life of the rubbing roller 55 is cited as a new requirement in the rubbing operation with a peripheral speed ratio.

  In the present embodiment, attention is focused on a configuration that makes the recording material difficult to stick to the fixing belt 53. Then, a rubbing roller 55 capable of appropriately roughening the surface of the fixing belt 53 is provided, and the rubbing roller 55 is brought into contact with the fixing belt 53 so that a contact area between the recording material P and the fixing belt 53 is sufficient. It was reduced to a state where separability could be secured, and the separability could be improved.

<Second Embodiment>
Next, a second embodiment according to the present invention will be described. The difference of the present embodiment from the first embodiment is that the first embodiment is characterized by a configuration in which the roughness of the belt surface is changed by the difference in speed ratio, whereas in this embodiment, the contact pressure is different. There is a feature in the configuration that changes the roughness of the belt surface due to the difference. Note that the image forming apparatus 100 and the fixing device 9 in the present embodiment are the same as the image forming apparatus 100 and the fixing device 9 described in the first embodiment. The same members as those in the first embodiment are denoted by the same reference numerals, and descriptions of components having the same configuration and function are omitted.

  The rubbing roller 55 of this embodiment is almost the same as that of the first embodiment. In this embodiment, the rubbing roller 55 is pressed against the fixing belt 53 and driven at a peripheral speed ratio to be rubbed. is not. In other words, in this embodiment, the surface of the fixing belt 53 is changed by pressing the rubbing roller 55 against the fixing belt 53 and increasing or decreasing the contact pressure. In this embodiment, since the rubbing roller 55 is a driven roller that rotates following the fixing belt 53, the rubbing roller driving device 204 that rotationally drives the rubbing roller 55 can be reduced.

  Along with this, the shape of the cam of the cam member 35 rotated by the rubbing roller pressurizing / separating motor 202 (see FIG. 5) of the rubbing roller 55 whose pressurization and separation are controlled by the pressurizing spring and the cam, Change the pressure so that it can be adjusted in multiple stages.

  In this embodiment, instead of the rubbing method of the first embodiment, that is, the method of changing the Rz of the belt surface by adding the speed ratio to the peripheral speed of the fixing belt 53 and the rubbing roller 55, the rubbing roller 55 The ten-point average roughness Rz on the surface of the fixing belt is changed by increasing or decreasing the contact pressure with respect to the fixing belt 53.

  Also in this embodiment, the rubbing mechanism 37 constitutes the execution unit of the present invention, and the control unit 141 constitutes the switching means of the present invention. The control unit 141 includes a mode (rubbing operation mode) executed last time stored in the storage unit 143, a mode (rubbing operation mode) executed in accordance with an image forming job input by an operation of the operation unit 142, and the like. Are compared to determine the rubbing condition. The controller 141 changes the rubbing state of the rubbing roller 55 against the fixing belt 53 by changing the contact pressure of the rubbing roller 55 against the fixing belt 53.

  The ten-point average roughness Rz of the surface of the fixing belt 53 that can obtain the optimum balance between the control of each paper type of the fixing device 9 and the separation property and image quality for each paper type in the present invention has already been described in the first embodiment. did. Therefore, in the following, instead of the variable control of the peripheral speed ratio in the first embodiment, the variable control of the contact pressure that can obtain the ten-point average roughness Rz that satisfies the optimum balance between the separability and the image quality will be described. To do.

  The ten-point average roughness Rz, which is the surface roughness of the fixing belt 53 for each target paper type, and the Rz value change amount and target change time at the time of paper type switching are as described in FIG. Here, the upper limit of the contact pressure of the rubbing roller 55 will be described. In other words, excessively pressing the rubbing roller 55 against the fixing belt 53 may affect the life of the fixing belt 53. Since the damage to the fixing belt 53 directly affects the life of the fixing device 9, it is necessary to check the contact pressure that does not damage the fixing belt 53.

FIG. 14 is a table showing the results of an endurance experiment on 250,000 sheets of plain paper continuously passing through the contact pressure of the rubbing roller 55 to several levels and the expected life of the fixing device. In this experiment, durability (250,000 sheets of normal paper passing durability) was examined in a state where the rubbing roller 55 was always in contact during paper passing. The basis weight of the plain paper used is 81 g / m ² .

  In the fixing belt durability results at each contact pressure shown in FIG. 14, the contact ratio (kgf), the presence or absence of damage to the fixing belt 53, and the number of durable sheets at the time of damage were examined. As a result, when the contact ratio is 0.5 kgf (≈4.903 N), 1.0 kgf (≈9.806 N), and 1.5 kgf (≈14.709 N), the fixing belt 53 is all used. There was no damage, and therefore the durable number at the time of damage was not known. When the contact ratio was 2.0 kgf (≈ 19.613 N), the fixing belt 53 was cracked, and the durable number at the time of breakage was 235,000. Further, even when the contact ratio was 2.5 kgf (≈24.516 N), the fixing belt 53 was cracked, and the durable number at the time of breakage was 193500.

  From these results, it was determined that the load value of 1.5 kgf was an appropriate value as the upper limit of the contact pressure.

  Next, the contact pressure that satisfies the rubbing operation mode conditions (i) to (vi) shown in FIGS. 11A and 11B is set. FIG. 15 shows the time required for Rz increase by the rubbing operation at each contact pressure, that is, the contact pressure of the rubbing roller 55 is applied to the fixing belt 53 having a ten-point average roughness Rz of 1.0 on the belt surface. It is a graph which shows the result of having made it contact | abut and measuring the time increase amount of Rz.

  In FIG. 15, the vertical axis represents the belt surface roughness Rz and the horizontal axis represents the required time s. The case where the load value is 1.5 kgf is indicated by a solid line, the case where the load value is 1.0 kgf is indicated by a thick broken line, and the case where the load value is 0.5 kgf is indicated by a thin broken line.

  From the result of FIG. 15, in order to shift Rz1.4 of (v), which is the most severe rubbing operation mode obtained in the first embodiment, to 1.7, a maximum contact pressure of 1.5 kgf (≈14 .709N) requires about 17 seconds. Here, since the target time is within 11 seconds, in the case of 17 seconds, a waiting time of 6 seconds occurs.

  As a measure for reducing such waiting time, it is conceivable to change the Rz optimum value of plain paper. However, looking at the transition time from Rz1.0 of this experiment result to 1.4, about 15 seconds are required, and considering the target time of 16 seconds for the rubbing operation mode (iv) (FIG. 11B). See), the optimal Rz value for plain paper should not be changed. In other words, if the method for generating the waiting time is used for both coated paper and plain paper, and plain paper and thin paper / recycled paper, the optimum Rz value of plain paper is changed to 1.5, etc. The waiting time for thin paper and recycled paper can be slightly shortened.

  In this embodiment, since the number of modes in which the standby time is generated is not increased, in the rubbing operation mode in which the ten-point average roughness Rz is increased, the load value is 1.5 kgf (≈14.709 N). It will be in contact.

  Next, the contact pressure for reducing the ten-point average roughness Rz (rubbing operation mode (i)-(iii)) is set. FIG. 16 shows the time required for uniformizing the belt surface by rubbing at each contact pressure, that is, the time Rz when the contact pressure of the rubbing roller 55 is brought into contact with the fixing belt 53 on the surface Rz1.7 at a low pressure. It is a graph which shows the result of having measured the amount of decline.

  In FIG. 16, the vertical axis represents the belt surface roughness Rz, and the horizontal axis represents the required time s. The case where the load value is 0.4 kgf (≈3.922N) is indicated by a solid line, the case where the load value is 0.3 kgf (≈2.941N) is indicated by a thick broken line, and the load value is 0.5 kgf (≈4.903N). ) Is indicated by a thin broken line.

  From the results of FIG. 16, it was found that the contact pressure that makes it possible to level the surface of the fixing belt 53 in the shortest time is 0.4 kgf. If the pressure is further reduced to 0.3 kgf, the required time increases. This is presumably because if the pressure is too low, the nip width between the fixing belt 53 and the rubbing roller 55 and the contact area of the abrasive grains become too small, and the leveling effect becomes small.

  Based on the above results, the rubbing operation mode (i)-(vi) in the present embodiment is determined. The shape of the cam member 35 that is driven to rotate by the rubbing roller pressurizing / separating motor 202 is a shape that can change the applied pressure in three stages. That is, there are three stages: a separated state, a pressurized state at a load value of 0.4 kgf, and a pressurized state at a load value of 1.5 kgf.

  The contents of the rubbing operation mode by changing the contact pressure are summarized in the table of FIG. That is, in FIG. 17, “Rz before rubbing”, “Rz after rubbing”, “Time required for paper type change (s)”, “Right before rubbing” corresponding to the rubbing operation modes (i) to (vi), respectively. “Contact ratio load value (kgf)” and “Rubbing operation required time (s)”.

  In the table of FIG. 17, in the rubbing operation mode (i), “Rz before rubbing” is 1.7 μm, “Rz after rubbing” is 1.0 μm, and “Time required for paper type change” is 20.0 s. The “contact specific load value” was 0.4 kgf, and the “required rubbing operation time” was 17.0 s. In the rubbing operation mode (ii), “Rz before rubbing” is 1.7 μm, “Rz after rubbing” is 1.4 μm, “Time required for paper type change” is 9.0 s, and “Contact specific load” The “value” was 0.4 kgf and the “required rubbing operation time” was 7.0 s. In the rubbing operation mode (iii), “Rz before rubbing” is 1.4 μm, “Rz after rubbing” is 1.0 μm, “Time required for paper type change” is 11.0 s, “Abutment specific load” The “value” was 0.4 kgf and the “required rubbing operation time” was 10.0 s.

  In the rubbing operation mode (iv), “Rz before rubbing” is 1.0 μm, “Rz after rubbing” is 1.4 μm, “Time required for changing paper type” is 16.0 s, “Abutting” The “specific load value” was 1.5 kgf, and the “required rubbing operation time” was 15.0 s. In the rubbing operation mode (v), “Rz before rubbing” is 1.4 μm, “Rz after rubbing” is 1.7 μm, “Time required for changing paper type” is 11.0 s, “Abutment specific load” The “value” was 1.5 kgf and the “required rubbing operation time” was 17.0 s. In the rubbing operation mode (vi), “Rz before rubbing” is 1.0 μm, “Rz after rubbing” is 1.7 μm, “Time required for changing paper type” is 27.0 s, “Abutting specific load” The “value” was 1.5 kgf and the “required rubbing operation time” was 32.0 s.

  Next, the specific control of the rubbing operation of this embodiment is executed according to the flowchart of FIG. 12, as in the case described in the first embodiment, but the rubbing operation mode ( i)-(vi) is changed to the rubbing operation mode by the contact pressure variable control of FIG.

  Here, the life of the rubbing roller 55 in the rubbing operation by the contact pressure variable control is confirmed. FIG. 18 is similar to the case where (ii) and (v) in the rubbing operation mode in FIG. 17 are alternately and continuously flowed, which is considered to have the most severe durability of the rubbing roller 55 in this embodiment. It is a graph showing the rubbing roller rubbing life when the contact pressure is fixed to 0.4 in this mode. This is the same as the endurance experiment of the first embodiment except that the content of the rubbing operation mode is different, and the experiment conditions and the evaluation method are also the same.

  In FIG. 18, the vertical axis represents the belt surface roughness Rz, and the horizontal axis represents the durable number. In the graph, the peripheral speed ratio control in which the rubbing operation modes (ii) and (v) are repeated is indicated by a fine broken line, and the rubbing speed in which the rubbing operation modes (ii) and (v) are repeatedly performed with the peripheral speed ratio fixed at 100%. Ratio control is indicated by a thick broken line. The contact pressure control for repeatedly performing the rubbing operation modes (ii) and (v) is indicated by a solid line, and the contact pressure for repeatedly performing the rubbing operation modes (ii) and (v) with the contact pressure fixed at 0.4 kg. Control is indicated by a two-dot chain line.

  From the results of FIG. 18, it was found that the life of the rubbing roller 55 is significantly improved in the rubbing by the contact pressure variable control compared to the rubbing by the peripheral speed ratio variable control. Further, compared with the peripheral speed ratio variable control, the difference in the durability life between the case where the contact pressure is fixed (the rubbing operation with the lowest load on the rubbing roller 55) and the case where it is not fixed is small. This is thought to be because the parameter sensitivity related to the life of the rubbing roller 55, such as abrasion of the abrasive material adhering to the rubbing roller 55, belt adhering matter, and hoisting of shaving powder, is dull compared to the peripheral speed ratio. It is done.

  From the experimental results and control described above, it can be shown that the rubbing method using the variable contact pressure control can achieve both the image quality and the separation property of thin paper / recycled paper, which are the object of the present invention. did it. In addition, the durability life of the rubbing roller 55 can be significantly improved as compared with the rubbing method using the peripheral speed ratio in the first embodiment.

  As described above, also in this embodiment, the rubbing mechanism 37 as the execution unit causes the rubbing roller 55 to slide the fixing belt 53 between the input of the image forming job signal for forming an image on the recording material and the start of the image forming job. Run the rubbing mode. When the basis weight of the recording material selected in the image forming job is the first basis weight (for example, thin paper / recycled paper), the control unit 141 serving as a switching unit switches as follows. That is, in the above mode, the surface roughness of the fixing belt 53 is larger than when the selected recording material has a second basis weight (for example, plain paper, coated paper) having a basis weight larger than the first basis weight. Change the rubbing condition. In this case, the contact pressure of the rubbing roller 55 against the fixing belt 53 when the basis weight of the recording material selected in the image forming job is the first basis weight is larger than the first basis weight of the selected recording material. The contact pressure of the rubbing roller 55 against the fixing belt 53 when the second basis weight is the basis weight is set larger.

  Alternatively, the control unit 141 as a switching unit can be configured to switch as follows when the thickness of the recording material selected in the image forming job is the first thickness (for example, thin paper / recycled paper). That is, the rubbing condition in the mode so that the surface roughness of the fixing belt 53 is larger than when the selected recording material is a second thickness (for example, plain paper, coated paper) that is larger than the first thickness. Switch. In this case, the contact pressure of the rubbing roller 55 against the fixing belt 53 when the thickness of the recording material selected in the image forming job is the first thickness is larger than the first thickness of the selected recording material. The contact pressure of the rubbing roller 55 against the fixing belt 53 at the second thickness is made larger.

  As described above, in the second embodiment as well as the first embodiment, it was possible to improve the separation of thin paper and recycled paper without degrading the image quality, which is the object of the present invention.

<Third Embodiment>
In the first and second embodiments described above, a new requirement accompanying the achievement of the object of the present invention, that is, the endurance life of the rubbing roller 55 and the occurrence of a standby time associated with an increase or decrease in Rz occurred. Therefore, in the third embodiment, the solution to the new requirement is achieved by combining the peripheral speed ratio variable control and the contact pressure variable control.

  The third embodiment according to the present invention will be described below. While the first embodiment is characterized by the configuration in which the roughness of the belt surface is changed depending on the speed ratio, the third embodiment appropriately uses the difference in speed ratio and the difference in contact pressure. However, it has a feature in the configuration that changes the roughness of the belt surface. Note that the image forming apparatus 100 and the fixing device 9 in the present embodiment are the same as the image forming apparatus 100 and the fixing device 9 described in the first embodiment. The same members as those in the first embodiment are denoted by the same reference numerals, and descriptions of components having the same configuration and function are omitted.

  The fixing device 9 according to this embodiment includes a rubbing roller driving device 204 that drives the rubbing roller 55 and a fixing roller driving device 203 that drives the fixing roller 51, and both rollers 55 as in the first embodiment. , 51 are independently driven and controlled by separate motors. (See Figure 3)

  Further, the cam member 35 driven by a sliding roller pressurizing / separating motor 202 that controls pressurization and separation by a not-shown pressure spring and cam is configured as follows. That is, the rubbing roller 55 can be adjusted in three stages so that it can be separated from the fixing belt 53, pressurized with a load value of 0.4 kgf (≈3.922 N), and pressurized with a load value of 1.5 kgf (≈14,709 N). It is configured in such a shape. Other configurations are the same as those in the first and second embodiments.

  In the present embodiment, the peripheral speed ratio variable control and the contact pressure variable control are combined to achieve the new requirements in the first and second embodiments while achieving the object of the present invention. . Also in this embodiment, the rubbing mechanism 37 constitutes an execution unit, and the control unit 141 constitutes a switching unit.

  First, in order to set the rubbing operation mode (i)-(vi) in the present embodiment, control (i)-(iii) in the case of reducing the ten-point average roughness Rz on the surface of the fixing belt 53 will be considered.

  When the contact pressure of the rubbing roller 55 is set to 0.4 kgf (≈3.922 N) and the fixing belt 53 is rubbed at a peripheral speed ratio of 100% according to the second embodiment described above, FIG. As shown, the Rz value can be changed within the paper type switching transition time.

  Further, from FIG. 18 showing the durability result, it can be seen that the smaller the peripheral speed ratio and the smaller the contact pressure can extend the durability life, and thus the above-mentioned rubbing method is optimal. Therefore, when reducing the Rz value, the peripheral speed ratio is set to 100% and the contact pressure is set to 0.4 kgf.

  Next, control ((iv)-(vi)) when increasing the Rz value will be considered. By increasing the peripheral speed ratio from the first embodiment, the Rz value can be increased in a short time. However, if the peripheral speed ratio is added, the durability life of the rubbing roller 55 is shortened accordingly. In the rubbing operation mode (iv), the rubbing operation can be completed within the paper type switching transition time at a peripheral speed ratio of 100% and a contact pressure of 1.5 kgf (≈14.709 N).

  However, in the rubbing operation mode (v), the above condition cannot be achieved only by the contact pressure control. Therefore, in this mode, it is desired to set control capable of extending the durable life of the rubbing roller 55 as much as possible while finishing the rubbing operation within the paper type switching transition time.

  As a specific method, the contact pressure is adjusted simultaneously with the peripheral speed ratio. An experiment was conducted in which the peripheral speed ratio was made as small as possible, the contact pressure was fixed at a maximum of 1.5 kgf, the peripheral speed ratio was varied, and the surface of the fixing belt 53 having an Rz value of 1.4 was rubbed for 9 seconds. It was. Thus, conditions for completing the rubbing operation are set within the paper type switching transition time in the rubbing operation mode (v).

  FIG. 19 is a graph showing the result of the above-described experiment, that is, the result of rubbing from the belt surface Rz1.4 with a contact pressure of 1.5 kgf for 9 seconds. In FIG. 19, the vertical axis represents the belt surface roughness Rz, and the horizontal axis represents the peripheral speed ratio%.

  From the graph of FIG. 19, the optimum rubbing operation for changing the Rz value from 1.4 to 1.7 μm within the paper type switching transition time in the rubbing operation mode (v) is the contact pressure of 1.5 kgf. It was shown that the setting of applying a peripheral speed ratio of 110% while applying pressure was appropriate.

  FIG. 20 is a graph showing the result of confirming the endurance life in this rubbing operation mode in FIG. In FIG. 20, the vertical axis represents the belt surface roughness Rz, and the horizontal axis represents the durable number.

  From the graph of FIG. 20, the durability life in the above mode by the combination control is about 95,000 sheets, which is slightly shorter than the case where the peripheral speed ratio is not provided, but is significantly longer than the case where only the peripheral speed ratio is provided. It can be seen that is extended. Therefore, it was confirmed that the sliding operation was optimum in the current configuration from the viewpoint of life.

  Based on the above experimental results, the contents of the rubbing operation modes (i) to (vi) in this embodiment are summarized in a table shown in FIG. The contents indicated by the rubbing operation modes (i) to (vi) are the same as those in FIG.

  In the table of FIG. 21, in the rubbing operation mode (i), the ten-point average roughness Rz before rubbing is 1.7 μm, the ten-point average roughness Rz after rubbing is 1.0 μm, and the paper type change required time. Is 20.0 seconds, the contact pressure load value is 0.4 kgf, the peripheral speed ratio is 100%, and the time required for the rubbing operation is 17.0 seconds. In the rubbing operation mode (ii), the ten-point average roughness Rz before rubbing is 1.7 μm, the ten-point average roughness Rz after rubbing is 1.4 μm, and the time required for changing the paper type is 9.0 seconds. The contact pressure load value is 0.4 kgf, the peripheral speed ratio is 100%, and the time required for the rubbing operation is 7.0 seconds. In the rubbing operation mode (iii), the 10-point average roughness Rz before rubbing is 1.4 μm, the 10-point average roughness Rz after rubbing is 1.0 μm, the paper type change required time is 11.0 seconds, The contact pressure load value is 0.4 kgf, the peripheral speed ratio is 100%, and the time required for the rubbing operation is 10.0 seconds.

  In the rubbing operation mode (iv), the 10-point average roughness Rz before rubbing is 1.0 μm, the 10-point average roughness Rz after rubbing is 1.4 μm, and the paper type change required time is 16.0. Second, the contact pressure load value is 1.5 kgf, the peripheral speed ratio is 100%, and the time required for the rubbing operation is 15.0 seconds. In the rubbing operation mode (v), the 10-point average roughness Rz before rubbing is 1.4 μm, the 10-point average roughness Rz after rubbing is 1.7 μm, and the time required for changing the paper type is 11.0 seconds. The contact pressure load value is 1.5 kgf, the peripheral speed ratio is 110%, and the time required for the rubbing operation is 9.0 seconds. In the rubbing operation mode (vi), the ten-point average roughness Rz before rubbing is 1.0 μm, the ten-point average roughness Rz after rubbing is 1.7 μm, and the time required for changing the paper type is 27.0 seconds. The contact pressure load value is 1.3 kgf, the peripheral speed ratio is 105%, and the time required for the rubbing operation is 24.0 seconds.

  Next, the specific control of the rubbing operation in the present embodiment is performed according to the flowchart of FIG. 12 as in the contents described in the first and second embodiments. However, the rubbing operation modes (i) to (vi) in FIG. 12 are replaced with the rubbing operation mode by the combination control in FIG.

  As described above, it has been shown that both the image quality and the separation property of thin paper / recycled paper can be achieved by the configuration and sequence of the present embodiment.

  Furthermore, in the present embodiment, the new life required for the first and second embodiments, the completion of the rubbing operation within the paper type switching transition time and the long life of the rubbing roller when the above conditions are satisfied. We were able to solve the problem.

  Note that in the first to third embodiments described above, the user sets the type of recording material (any of the type, brand, thickness, weight, etc.) conveyed to the fixing nip N by the operation unit 142. Based on this, it was possible to determine the rubbing operation with respect to the fixing belt 53. However, the present invention is not limited to this. For example, in the apparatus main body 100a, a means for detecting at least one of the thickness, the weight, and the stiffness of the recording material conveyed to the fixing nip portion N before the fixing process of the fixing apparatus 9, or the installation environment temperature of the image forming apparatus 100 Alternatively, means for detecting the humidity, the temperature of the recording material or the moisture content is provided. It is also possible to configure to determine the rubbing operation with respect to the fixing belt 53 based on detection by these means.

  In the first to third embodiments, as the image forming apparatus 100, the tandem intermediate transfer in which the image forming portions Pa, Pb, Pc, and Pd are arranged in parallel to the intermediate transfer belt 130 that is an image carrier. A color printer was illustrated. However, the present invention is not limited to this. That is, a one-drum type intermediate transfer color printer that sequentially forms each color toner image on one image carrier and transfers it onto the intermediate transfer member, or each color toner image from the image carrier to the recording material without the intermediate transfer member. A tandem direct transfer color printer that directly transfers images may be used. Furthermore, other image forming apparatuses such as a copying machine and a facsimile may be used instead of the printer.

  37 ... execution unit (sliding mechanism), 53 ... image heating member (fixing belt), 55 ... rubbing member (sliding roller), 100 ... image forming apparatus, 141 ... switching means (control unit), 143 ... storage unit , P ... Recording material

Claims (7)

In an image forming apparatus comprising: an image heating member for heating an image formed on a recording material; and a rubbing member for contacting the surface of the image heating member and rubbing the image heating member.
An execution unit that executes a mode in which the rubbing member rubs the image heating member from the input of an image forming job signal for forming an image on a recording material to the start of the image forming job;
When the basis weight of the recording material selected in the image forming job is the first basis weight, the image heating member is more than when the selected recording material is the second basis weight, which is a basis weight larger than the first basis weight. Switching means for switching the rubbing condition in the mode so as to increase the surface roughness of the image.   The circumferential speed ratio between the image heating member and the rubbing member when the basis weight of the recording material selected in the image forming job is the first basis weight is larger than the first basis weight of the selected recording material. 2. The image forming apparatus according to claim 1, wherein a peripheral speed ratio between the image heating member and the rubbing member at a second basis weight that is a basis weight is larger.   The contact pressure of the rubbing member against the image heating member when the basis weight of the recording material selected in the image forming job is the first basis weight is a basis weight where the selected recording material is larger than the first basis weight. The image forming apparatus according to claim 1, wherein the contact pressure of the rubbing member against the image heating member at the second basis weight is an amount. In an image forming apparatus comprising: an image heating member for heating an image formed on a recording material; and a rubbing member for contacting the surface of the image heating member and rubbing the image heating member.
An execution unit that executes a mode in which the rubbing member rubs the image heating member from the input of an image forming job signal for forming an image on a recording material to the start of the image forming job;
When the thickness of the recording material selected in the image forming job is the first thickness, the surface roughness of the image heating member is smaller than when the selected recording material is the second thickness that is larger than the first thickness. An image forming apparatus comprising: switching means for switching a rubbing condition in the mode so as to increase.   The peripheral speed ratio between the image heating member and the rubbing member when the thickness of the recording material selected in the image forming job is the first thickness is such that the selected recording material is larger than the first thickness. The image forming apparatus according to claim 4, wherein the image forming apparatus is larger than a peripheral speed ratio between the image heating member and the rubbing member at the second thickness.   The contact pressure of the rubbing member against the image heating member when the thickness of the recording material selected in the image forming job is the first thickness is such that the selected recording material is thicker than the first thickness. The image forming apparatus according to claim 4, wherein the pressure is larger than a contact pressure of the rubbing member against the image heating member when the thickness is two.   The storage unit stores a previously executed mode, and the switching unit determines a rubbing condition as compared with a previously executed mode and a mode executed according to an input image forming job. Item 7. The image forming apparatus according to any one of Items 1 to 6.

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