JP6613836B2 - Fixing device - Google Patents

Description

  The present invention relates to a fixing device, and more specifically, a transferred member having an unfixed image formed of toner on one surface is passed through a nip portion formed by press-contacting a fixing rotator and a pressure rotator. Thus, the present invention relates to a fixing device that heats and pressurizes a toner image to melt and fix the toner image on a transfer member.

  In an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having these functions, an electrostatic latent image corresponding to an original is formed on a photosensitive drum, and the electrostatic latent image is formed on the electrostatic latent image. The toner image is made to adhere to the toner image, and the visualized toner image is transferred onto the member to be transferred. Thereafter, the toner image on the member to be transferred is fixed and discharged.

  As a device for fixing an unfixed image (hereinafter also referred to as “toner image”) of toner transferred onto a transfer member, a fixing rotator provided with heating means such as a halogen lamp, a pressure rotator, A heat roller fixing type fixing device that heats and pressurizes while pinching and transporting the transferred member on which the toner image is formed at the nip formed by pressure contact, due to the simplicity of the device configuration. Widely used.

  In such a conventional fixing device, in a region through which the member to be transferred has passed, heat is taken away by the member to be transferred, and the temperature is lowered. For this reason, a temperature distribution is generated between a region through which the transfer member passes and a region through which the member to be transferred does not pass. Further, when a pressure roller having an elastic layer is used, if the temperature distribution is generated, a difference in outer diameter occurs due to thermal expansion, and the peripheral speed of the pressure roller is different in the axial direction. Therefore, for example, when a large size paper is fixed after a small size paper is continuously fixed, problems such as uneven fixing of images and hot offset may occur due to the temperature distribution generated as described above. is there. Further, when the sheet conveying speed of the fixing device is different in the axial direction, noise such as “bleeding” may occur in the image, or the sheet may be wrinkled.

  Therefore, a technique has been proposed in which a temperature-uniforming roller such as a heating roller or a heat pipe is brought into contact with the fixing rotator or the pressure rotator to eliminate the temperature distribution in the rotation axis direction of the fixing rotator or the pressure rotator. ing.

  According to the proposed technique, the temperature difference in the rotation axis direction between the fixing rotator and the pressure rotator is greatly improved. However, when the fixing process is performed for a long period of time, toner, paper dust, and the like may adhere to the fixing rotator and the pressure rotator, and may be transferred and fixed to the surface of the temperature-uniforming roller. If the toner or the like is fixed to the surface of the temperature-uniforming roller, the fixing member may damage the fixing rotator or the pressure rotator in contact with the temperature-uniforming roller.

  Therefore, the present applicant proposes a technique in which the surface temperature of the temperature-uniforming roller is heated to a temperature equal to or higher than the melting temperature of the toner, and the brush roller is rotated in contact with the temperature-uniforming roller to scrape off the fixed matter on the surface of the temperature-uniforming roller. (Patent Document 1).

JP 2011-22263 A

  However, in subsequent studies, it has been found that there are cases in which the deposit on the surface of the temperature equalizing roller cannot be sufficiently scraped even if the temperature equalizing roller is simply heated as in the proposed technique. That is, when paper with a large amount of calcium carbonate used as a filler is used, adhesion of a mixture of toner and paper powder (calcium carbonate) increases on the surface of the soaking roller. It was found that the mixture adhering to the surface of the film could not be sufficiently scraped off with a brush roller.

  Accordingly, the present invention has been made in view of such a conventional problem, and an object of the present invention is to perform soaking in a fixing device that uniformizes the temperature distribution in the rotation axis direction of the pressure rotator with a soaking roller. An object of the present invention is to reliably remove the deposits on the roller surface.

The fixing device of the present invention that achieves the above object includes a fixing rotator, a first heating unit that heats the fixing rotator, a pressure rotator that presses against the fixing rotator to form a nip portion, A temperature-uniforming roller that contacts the surface of the pressure rotator to make the temperature distribution in the rotation axis direction uniform, and a second heating unit that heats the temperature-uniforming roller and that is different from the first heating unit. A heating means and a brush roller for cleaning the surface of the temperature-uniforming roller are provided, and a toner image is heated by passing a member to be transferred on which an unfixed image of toner is formed on one side through the nip portion. A fixing device that pressurizes and melts and fixes to a member to be transferred, and the temperature of the soaking roller is 9.16 × above a temperature at which the storage elastic modulus G ′ of the toner is 3.12 × 10 ⁴ Pa. It was heated to 10 2 ^Pa and becomes a temperature below the temperature-uniforming roller Characterized by cleaning the surface with the brush roller.

More specifically, in the above configuration, the temperature of the soaking roller is heated to a temperature at which the storage elastic modulus G ′ of the mixture of the toner 50 wt% and calcium carbonate 50 wt% is 5.74 × 10 ⁴ Pa. The surface of the soaking roller may be cleaned with the brush roller.

  More specifically, as the above configuration, the brush roller and the temperature-uniforming roller can be contacted and separated from each other, and during the temperature raising operation for heating the fixing rotating body to a predetermined fixing temperature, During the fixing operation in which pressure is applied to melt and fix the transferred member, the temperature-uniforming roller and the pressure rotator are in contact with each other, and the temperature-uniforming roller is driven to rotate by the rotation of the pressure rotator. The roller and the soaking roller may be separated from each other.

  More specifically, as the above-described configuration, the soaking roller and the pressure rotating body can be contacted / separated, and the brush roller and the soaking roller can also be contacted / separated, and the brush roller When the temperature equalizing roller is cleaned, the temperature equalizing roller and the pressure rotating body are separated from each other, and the brush roller and the temperature equalizing roller may be in contact with each other and driven to rotate.

More specifically, the brush roller has a plurality of heat-resistant resin fibers on the surface thereof, the planting density of the heat-resistant resin fibers is 7740 / inch ^{2 to} 65000 / inch ² , and the fiber diameter is It is good also as a structure which is 40 micrometers or more and 500 micrometers or less, and a length is the range of 1.5 mm or more and 1.8 mm or less.

  More specifically, as the above-described configuration, the soaking roller may have a release layer having a critical surface tension of 14 mN / m or more and 18 mN / m or less on the surface.

  According to the fixing device according to the present invention, even if a sheet with a large amount of calcium carbonate used as a filler is used, deposits on the surface of the temperature equalizing roller can be reliably removed. Thereby, it is prevented that the surface of the pressure rotating body with which the soaking roller contacts is damaged by the deposits.

1 is a schematic diagram illustrating an example of an image forming apparatus (printer) equipped with a fixing device of the present invention. It is a schematic block diagram which shows an example of the fixing device of this invention, Comprising: It is a state figure at the time of the non-cleaning of a soaking | uniform-heating roller. It is a state figure at the time of the cleaning of the soaking | uniform-heating roller by a brush roller. It is a graph which shows the change of the storage elastic modulus G '(Pa) with respect to the heating temperature by the difference in the deposit | attachment of a soaking roller.

  Hereinafter, the fixing device according to the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to these embodiments.

  FIG. 1 is a schematic view showing an example of an image forming apparatus equipped with a fixing device according to the present invention. The image forming apparatus in FIG. 1 is a tandem digital color printer (hereinafter, simply referred to as “printer”). Of course, in addition to a printer, the present invention can also be applied to a copying machine having a scanner, a facsimile, or a multi-function machine having these functions combined. In the following, when it is necessary to clarify whether the device or member to be described is yellow (Y), magenta (M), cyan (C), or black (B), The description will be made by adding the characters “(Y)”, “(M)”, “(C)”, and “(B)” to the reference numerals, and otherwise omitting those characters.

  The printer 1 includes an intermediate transfer belt 11 at substantially the center of the inside thereof. The intermediate transfer belt 11 is stretched around the outer periphery of the roller 12, the tension roller 13, and the guide rollers 14 and 15, and is driven to rotate counterclockwise. The tension roller 13 is slidably attached to the outside and is urged by the pressing spring S from the inside to the outside of the intermediate transfer belt 11. Thus, the intermediate transfer belt 11 is always in a tensioned state.

  Below the lower horizontal portion of the intermediate transfer belt 11, four image forming portions 2Y, 2M, 2C, and 2B respectively corresponding to the colors of yellow (Y), magenta (M), cyan (C), and black (B). Are arranged in this order along the intermediate transfer belt 11. Each of the image forming units 2Y, 2M, 2C, and 2B includes photosensitive drums 21Y, 21M, 21C, and 21B, respectively. Around each of the photosensitive drums 21Y, 21M, 21C, and 21B, the chargers 22Y, 22M, 22C, and 22B, the print head units 23Y, 23M, 23C, and 23B, and the developing unit 24Y are sequentially arranged along the rotation direction. 24M, 24C, and 24B and cleaners 25Y, 25M, 25C, and 25B are disposed, respectively. The print head units 23Y, 23M, 23C, and 23B are configured by a large number of LEDs arranged in the main scanning direction parallel to the axial direction of the photosensitive drum.

  Primary transfer rollers 30Y, 30M, 30C, and 30B are provided at positions facing the respective photosensitive drums 21Y, 21M, 21C, and 21B with the intermediate transfer belt 11 interposed therebetween. A secondary transfer roller 16 is pressed against the portion of the intermediate transfer belt 11 supported by the roller 12. A nip portion between the secondary transfer roller 16 and the intermediate transfer belt 11 becomes a secondary transfer region 17. The toner image formed on the intermediate transfer belt 11 in the secondary transfer region 17 is transferred to the conveyed paper (transfer target member) P.

  A paper feed cassette 91 is detachably disposed at the bottom of the printer 1. The sheets P stacked and accommodated in the sheet feeding cassette 91 are pulled out one by one from the uppermost sheet by the rotation of the sheet feeding roller 92 and are sent out to the transport path 93. The conveyance path 93 extends from the paper feed cassette 91 to the paper discharge tray 98 through the nip portion of the timing roller pair 94, the secondary transfer region 17, and the fixing device T. The paper P sent out from the paper feed cassette 91 is conveyed to the timing roller pair 94 and is sent out to the secondary transfer area 17 at a predetermined timing.

  The fixing device T includes a fixing roller (fixing rotator) 4, a pressure roller (pressure rotator) 5 that is in pressure contact with the fixing roller 4, and a magnetic flux generator (first unit) that is spaced apart from the outer periphery of the fixing roller 4. 1 heating means) 6. As the paper P passes through the nip portion between the fixing roller 4 and the pressure roller 5, the toner image secondarily transferred onto the paper P is heated and melted and fixed on the paper P. Details of the fixing device T will be described later.

  A schematic operation of the printer 1 having such a configuration will be described. First, in the full color mode for outputting a color image, when an image signal is input from an external device (for example, a personal computer) to an image signal processing unit (not shown) of the printer 1, the image signal processing unit converts the image signal to yellow, A digital image signal color-converted to cyan, magenta, and black is created, and this signal is transmitted to the LED drive circuit for the print head. This drive circuit performs exposure by causing the print head units 23Y, 23M, 23C, and 23B of the image forming units 2Y, 2M, 2C, and 2B to emit light based on the input digital signals. This exposure is performed with a time difference in the order of the print head units 23Y, 23M, 23C, and 23B. Thereby, electrostatic latent images for the respective colors are formed on the surfaces of the photosensitive drums 21Y, 21M, 21C, and 21B.

  To the electrostatic latent images formed on the photosensitive drums 21Y, 21M, 21C, and 21B, toners are attached by the developing devices 24Y, 24M, 24C, and 24B to be visualized (developed), and toners of the respective colors. Become a statue. Then, the toner images of the respective colors are sequentially primary-transferred and superimposed on the intermediate transfer belt 11 that rotates counterclockwise in the figure by the action of the primary transfer rollers 30Y, 30M, 30C, and 30B.

  The toner image formed on the intermediate transfer belt 11 in this way reaches the secondary transfer region 17 as the intermediate transfer belt 11 moves. On the other hand, the paper P sent out from the paper feed cassette 91 to the transport path 93 is transported to the secondary transfer region 17 by the timing roller pair 94 at the timing when the toner image reaches the secondary transfer region 17. A voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roller 16. As a result, in the secondary transfer region 17, the superimposed color toner images are secondarily transferred collectively from the intermediate transfer belt 11 to the paper P. The toner remaining on the intermediate transfer belt 11 after the secondary transfer is collected by a belt cleaner (not shown).

  The sheet P onto which the toner image has been secondarily transferred is sent to the fixing device T through the conveyance path 93, where the toner image is fixed on the sheet P by passing through the nip portion. Then, the paper P is discharged to the paper discharge tray 98.

  2 and 3 are schematic views of the fixing device T used in the printer 1 of FIG. FIG. 2 is a state diagram at the time of a temperature raising operation for heating the fixing roller 4 to a predetermined fixing temperature and at the time of a fixing operation for heating and pressurizing a toner image to melt and fix the toner image on a transfer target member. 8 is a state diagram at the time of cleaning of the temperature-uniforming roller 7 according to FIG.

  In the fixing device T, the fixing roller 4 and the pressure roller 5 are pressed against each other, and a magnetic flux generator 6 is provided on the outer periphery of the fixing roller 4 at a position facing the fixing roller 4 at a distance. A soaking roller 7 is in pressure contact with the pressure roller 5, and a brush roller 8 is provided near the surface of the soaking roller 7. Hereinafter, each member will be described in order.

  The fixing roller 4 includes a hollow cylindrical cored bar 41, an elastic layer 42 formed on the outer periphery of the cored bar 41, and an endless belt 43 provided in an unbonded state on the outer periphery of the elastic layer 42. As a material of the cored bar 41, a heat resistant resin such as polyphenylene sulfide (PPS) can be used in addition to a metal material such as aluminum or iron. When electromagnetic induction heating means is used as the heating means as in the present embodiment, it is preferable to use a nonmagnetic material such as aluminum in order to prevent the cored bar 41 from being heated by electromagnetic induction.

The elastic layer 42 is formed from a member having heat resistance and elasticity. For example, a silicone sponge body is suitable as such a member. If a sponge body is used as the elastic layer 42, the endless belt 43 can be insulated and held, and at the same time, the endless belt 43 can be bent, so that the length of the nip portion between the fixing roller 4 and the pressure roller 5 can be increased. . For example, when a silicone sponge material is used for the elastic layer 42, the thickness is preferably in the range of 2 mm to 14 mm, more preferably in the range of 6 mm to 12 mm. The hardness of the elastic layer 42 is preferably in the range of 20 degrees to 60 degrees, more preferably in the range of 20 degrees to 50 degrees with an Asker C type rubber hardness meter (manufactured by Kobunshi Keiki Co., Ltd.).

  The endless belt 43 has a laminated structure of an electromagnetic induction heat generating layer 431, an elastic layer 432, and a release layer 433 from the inner peripheral side as shown in the partial enlarged view of FIG. The endless belt 43 is provided on the outer periphery of the elastic layer 42 in an unbonded state. The electromagnetic induction heat generating layer 431 is a layer that generates Joule heat by excitation by the magnetic flux generator 6. The material is preferably a magnetic metal material such as nickel, magnetic stainless steel, or iron. Moreover, you may use what mixed the magnetic metal particle in resin. The thickness of the electromagnetic induction heat generating layer 431 is preferably, for example, in the range of 10 μm to 100 μm, and more preferably in the range of 20 to 50 μm.

  The elastic layer 432 of the endless belt 43 is a layer for improving the adhesion between the paper P and the surface of the endless belt 43, and a member having heat resistance and elasticity is used. For example, heat-resistant elastomers such as silicon rubber and fluorine rubber that can withstand use at the fixing temperature are preferably used. Note that various fillers may be mixed in the elastic layer 432 for the purpose of thermal conductivity, reinforcement, and the like. Examples of the heat conductive particles include diamond, silver, copper, aluminum, marble, and glass. In addition, silica, alumina, magnesium oxide, boron nitride, beryllium oxide, and the like can be used. The thickness of the elastic layer 432 is, for example, preferably in the range of 10 μm to 800 μm, more preferably in the range of 100 μm to 300 μm. Further, the hardness of the elastic layer 432 is, for example, preferably in the range of 1 to 80 degrees, more preferably in the range of 5 to 30 degrees with a JIS A type hardness meter. As the silicone rubber, one-component, two-component or three-component or more silicone rubber, LTV type, RTV type or HTV type silicone rubber, condensation type or addition type silicone rubber can be used.

  The release layer 433 of the endless belt 43 is a layer for improving the surface release property of the endless belt 43, and a material that can withstand use at a fixing temperature is used. For example, a tube made of tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) is exemplified. The thickness of the release layer 433 is preferably, for example, in the range of 5 μm to 100 μm, and more preferably in the range of 10 μm to 50 μm. In addition, you may add a electrically conductive material, an abrasion-resistant material, a good heat conductive material, etc. as a filler in the mold release layer 433 as needed. Further, in order to improve the interlayer adhesion, an adhesion treatment with a primer or the like may be performed.

  In FIG. 2, the pressure roller 5 is formed by laminating an elastic layer 52 and a release layer (not shown) in this order on a hollow cylindrical cored bar 51. As the metal core 51, a heat resistant resin such as PPS can be used in addition to a metal material such as aluminum or iron. As the elastic layer 52, the same material as that of the elastic layer 42 of the fixing roller 4 can be preferably used here. As the release layer, the same material as the release layer 432 of the endless belt 43 can be preferably used here.

  The pressure roller 5 is biased toward the fixing roller 4 by a biasing member such as a spring, and forms a nip portion with the fixing roller 4. For example, the pressure roller 5 may be pressed against the fixing roller 4 with a load of 300 N to 500 N so that the length of the nip portion is within a range of 5 mm to 10 mm. Note that the load may be changed according to the type of the paper P or the like. Further, here, the pressure roller 5 is rotationally driven at a predetermined speed by a drive mechanism such as a motor. On the other hand, the fixing roller 4 is rotated by the rotation of the pressure roller 5 by the pressure frictional force with the pressure roller 5. Note that these rotational driving may be performed by using the fixing roller 4 as a main drive and the pressure roller 5 as a driven rotation.

  In FIG. 2, the magnetic flux generator 6 is configured by a coil part 61 and a core part 62 covered with a coil hobbin 63. The coil unit 61 is wound around a coil hobbin 63 disposed so as to cover a part of the outer periphery of the fixing roller 4, and a litz wire bundled with thin wires is wound in the axial direction (in the direction perpendicular to the paper in FIG. 2). It is an extension. The coil hobbin 63 is made of a resin material having high heat resistance and holds the coil part 61. The core portion 62 is made of a ferromagnetic material such as ferrite (having a relative permeability of about 1000 to 3000), and is for forming an efficient magnetic flux toward the heat generating layer, and extends in the axial direction. It is installed so as to face the provided coil part 61.

  A high-frequency inverter (not shown) is connected to the magnetic flux generator 6, and an AC current of 10 kHz to 100 kHz is applied to the coil unit 61 from the high-frequency inverter, whereby the electromagnetic induction heat generating layer 431 of the endless belt 43 generates heat. However, the surface temperature of the endless belt 43 is maintained at a predetermined temperature.

  The soaking roller 7 includes a hollow cylindrical base 71, a release layer 72 formed on the surface of the base 71, and a halogen heater (second heating means) 73 disposed at the axial center of the base 71. Prepare. For the release layer 72, a material that can withstand use at a fixing temperature is used. For example, a fluororesin such as PFA, PTFE, FEP, ETFE, or a mixture thereof is preferably used. Although there is no limitation in particular in the thickness of the mold release layer 72, Usually, it is preferable that the layer thickness after apply | coating and baking the said fluororesin becomes the range of 20 micrometers-50 micrometers. The critical surface tension of the release layer 72 is preferably in the range of 14 mN / m to 18 mN / m. The surface hardness of the release layer 72 is preferably in the range of “B” to “2B” by the pencil test hardness evaluation method when heated at a temperature of 200 ° C.

  A temperature sensor 74 is disposed at the outer peripheral separation position of the temperature equalizing roller 7. The halogen heater 73 is controlled to be turned on and off based on the temperature detected by the temperature sensor 74, and the soaking roller 7 is maintained at a desired temperature.

  The soaking roller 7 is biased toward the pressure roller 5 by a biasing member (not shown) such as a spring, and forms a nip portion with the pressure roller 5. For example, the soaking roller 7 may be pressed against the pressure roller 5 with a load of 100 N to 120 N so that the length of the nip portion is within a range of 1 mm to 5 mm. The soaking roller 7 is rotated by the rotation of the pressure roller 5 by the pressure frictional force with the pressure roller 5.

  The soaking roller 7 is movable with respect to the pressure roller 5 between a pressure contact position and a separation position. Specifically, the temperature-uniforming roller 7 is in a non-contact position with the brush roller when it comes into contact with the pressure roller 5, and comes into contact with the brush roller when it is away from the pressure roller 5. . Conventionally known moving means such as a solenoid can be used for such movement of the soaking roller 7.

  As shown in FIG. 2, a soaking roller 7 is applied during a temperature raising operation for heating the fixing roller 4 to a predetermined fixing temperature and during a fixing operation for heating and pressurizing the toner image to melt and fix the toner image on the transfer member. The pressure roller 5 is brought into pressure contact. At this time, the soaking roller 7 and the brush roller 8 are separated from each other. The soaking roller 7 is driven and rotated by the driving rotation of the pressure roller 5.

  On the other hand, when the soaking roller 7 is cleaned by the brush roller 8, the soaking roller 7 is separated from the pressure roller 5 and is in contact with the brush roller 8 as shown in FIG. 3. A rotation driving gear is provided on the end shaft portion of the temperature-uniforming roller 8. When the temperature-uniforming roller 7 is located away from the pressure roller 5, the gear provided on the pressure roller 5. Then, the drive is transmitted to the gear through the intermediate gear, so that the soaking roller 7 and the brush roller 8 are rotationally driven. In addition, the rotation direction of the temperature-uniforming roller 7 and the brush roller 8 may be the same direction or a reverse direction at the contact portion.

  The brush roller 8 as a cleaning means is rotatably provided so as to be in contact with the surface of the soaking roller 7. The brush roller 8 is formed by winding a strip-shaped base fabric in which a large number of heat-resistant resin fibers 82 are planted around a metal core 81 in a spiral shape. As a material of the heat resistant resin fiber 82, for example, polyphenylene sulfide having a heat resistant temperature of 160 to 190 ° C. can be suitably used.

  The length of the heat-resistant resin fiber 82 is not particularly limited, but is preferably in the range of 1.5 mm to 1.8 mm in order to suppress the hair fall of the heat-resistant resin fiber 82. Moreover, it is preferable that the front-end | tip of the heat resistant resin fiber 82 is made into the end surface perpendicular | vertical with respect to the length direction. The length of the heat-resistant resin fiber 82 is the length of the free fiber part excluding the fiber part fixed to the cored bar 81.

The planting density of the heat-resistant resin fibers 82 is preferably in the range of 7740 / inch ^{2 to} 65000 / inch ² . The fiber diameter is preferably in the range of 40 μm to 500 μm.

Table 1 shows that the critical surface tension of the release layer 72 of the temperature-uniforming roller 7 is changed in five stages in the range of 14.1 mN / m to 22.3 mN / m, and the fiber planting density of the brush roller is 7740 / inch. ² shows the evaluation results of the cleaning state of the surface of the temperature-uniforming roller in the case of changing to three stages of 15470 lines / inch ² and 65000 lines / inch ² . “◯” indicates that the cleaning property is good, and “×” indicates that the deposit remains on the surface of the soaking roller. The surface temperature of the soaking roller was set to a temperature range in which the storage elastic modulus G ′ of the deposit was 0.574 × 10 ⁵ (Pa) to 0.916 × 10 ³ (Pa).

As understood from Table 1, when the critical surface tension of the release layer 72 of the temperature equalizing roller 7 is in a preferable range of 14 mN / m to 18 mN / m, the heat-resistant resin fibers 82 are implanted. The cleaning property is good when the density is in the range of 7740 lines / inch ^{2 to} 65000 lines / inch ² .

  The brush roller 8 is rotationally driven from a driving source of the pressure roller 5 via a gear (not shown), and rotates so that the heat-resistant resin fiber 82 contacts the surface of the temperature-uniforming roller 7. As described above, the rotation direction of the brush roller 8 may be either the same direction as the heat equalizing roller 7 or the reverse direction at the contact portion. At that time, it is preferable that the peripheral speed of the tip portion of the heat-resistant resin fiber 82 is the same as or faster than the peripheral speed of the surface of the temperature-uniforming roller 7. The peripheral speed of the surface of the soaking roller 7 and the peripheral speed of the tip of the brush roller 8 are usually preferably in the range of 150 to 270 mm / sec.

  The contact and separation between the brush roller 8 and the temperature-uniforming roller 7 are performed by the movement of the temperature-uniforming roller 7 as described above, but may of course be performed by the movement of the brush roller 8. As a means for moving the brush roller 8, a conventionally known moving means such as a solenoid can be used.

In the fixing device T having such a configuration, when the temperature equalizing roller 7 is cleaned, the halogen heater 73 of the temperature equalizing roller 7 is energized, and the surface temperature of the temperature equalizing roller 7 is the storage elastic modulus G of the toner. Heat until 'reaches a temperature of 3.12 × 10 ⁴ Pa and below a temperature of 9.16 × 10 ² Pa. A more preferable lower limit of heating is a temperature at which the storage elastic modulus G ′ of the mixture of 50 wt% toner and 50 wt% calcium carbonate becomes 5.74 × 10 ⁴ Pa.

If the surface temperature of the temperature-uniforming roller 7 is less than the temperature at which the storage elastic modulus G ′ of the toner is 3.12 × 10 ⁴ Pa, the wax component from the toner adhering to the surface of the temperature-uniforming roller bleeds. There is little ejection, and the releasability of the toner to the soaking roller does not increase. In addition, when the inventor observed a mixture on the surface of the temperature-uniforming roller in the market return fixing device, the deposit on the surface of the temperature-uniforming roller is usually a mixture of calcium carbonate and toner contained in the paper. In this mixture, the maximum content of calcium carbonate was 50 wt%. Since the wax component exuded from the toner is easily absorbed by calcium carbonate, the deposit cannot be scraped off from the surface of the temperature-uniforming roller unless the heating temperature is increased as the deposit contains more calcium carbonate. Therefore, in the present invention, the preferable lower limit value of the heating temperature of the temperature-uniforming roller is determined as a temperature at which the storage elastic modulus G ′ of the mixture of 50 wt% toner and 50 wt% calcium carbonate becomes 5.74 × 10 ⁴ Pa.

On the other hand, when the surface temperature of the soaking roller 7 exceeds the temperature at which the storage elastic modulus G ′ of the toner becomes 9.16 × 10 ² Pa, the deposit on the soaking roller 7 surface becomes overmelted. Adhesive strength with the surface of the temperature-uniforming roller 7 is strengthened, and cohesive failure occurs in the adhered material, and the tip side of the adhered material is scraped off by the brush roller, but the base side of the adhered material (the temperature-uniforming roller side) is uniformed. It remains on the heat roller 7 and causes a cleaning failure.

  FIG. 4 is a graph showing a change in the storage elastic modulus G ′ (Pa) with respect to the heating temperature due to the difference in the deposits on the soaking roller. “◯” marks in the graph indicate good cleaning properties (Examples 1 to 5), and “●” marks indicate poor cleaning (Comparative Examples 1 to 6). As can be seen from FIG. 4, the storage elastic modulus G ′ (Pa) is increased as the temperature increases in both cases where the deposit is “toner only” and “toner + calcium carbonate”. descend. Further, comparing the case where the adhering substance is “toner only” and the case of “toner + calcium carbonate”, in order to obtain the same storage elastic modulus G ′ (Pa), the case of “toner + calcium carbonate” is better. , The temperature needs to be higher than in the case of “toner only”. This is because, as described above, when the deposit is a mixture of toner and calcium carbonate, the wax component that has oozed out of the toner is absorbed by calcium carbonate.

  When the surface temperature of the temperature-uniforming roller is heated to the predetermined temperature range, the temperature-uniforming roller 7 and the brush roller 8 are rotated to adhere to the surface of the temperature-uniforming roller 7 such as toner and paper dust. Is scraped off with the heat-resistant resin fiber 82 of the brush roller 8. The soaking roller 7 and the brush roller 8 may be rotated before reaching the predetermined temperature range.

The temperature at which the storage elastic modulus G ′ of the toner is 3.12 × 10 ⁴ Pa and the temperature at which it is 9.16 × 10 ² Pa and the storage elastic modulus G ′ of the mixture of the toner 50 wt% and calcium carbonate 50 wt% are The temperature at which 5.74 × 10 ⁴ Pa is obtained can be known by measuring in advance the correlation between the storage elastic modulus G ′ (Pa) of the toner or the mixture and the temperature.

  There is no particular limitation on the cleaning time, but it is usually about several tens of seconds. The cleaning time is preferably performed every time the cumulative number of image formations exceeds a predetermined number (for example, 100,000).

  As described above, in the embodiment described above, the electromagnetic induction heating method is used as the first heating means. However, the first heating means of the present invention is not limited to this, and for example, infrared irradiation heating with a halogen lamp or the like. Conventionally known heating means can be used. In addition, when using heating means other than the electromagnetic induction heating method, the electromagnetic induction heat generating layer 431 made of a magnetic metal material is not necessary as a configuration of the endless belt 43.

The storage modulus G ′ (Pa) of the toner and the mixture in the present invention was measured as follows.
(measuring equipment)
Anton Paar's MCR302
(Measurement sample preparation conditions)
Sample amount: 0.2g
Sample shape: Diameter 11 mm Thickness: 2 mm Pressure molding (measurement conditions)
Measurement temperature range: 30 ° C to 200 ° C Temperature increase rate: 3 ° C / min
Measurement interval: 0.7 ° C
Measurement frequency: 1 Hz
Measurement jig: Parallel plate (sample is sandwiched between two flat plates)
Angular amplitude (distortion): 0.01%

  In the fixing device of the present invention, the temperature distribution in the rotation axis direction of the fixing rotator and the pressure rotator is equalized by the temperature-uniforming roller, and the deposit on the surface of the temperature-uniforming roller is removed by the brush roller. It is useful because the fixing process can be carried out stably over a long period of time.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these examples at all.

(Examples 1 to 3, Comparative Examples 1 and 2)
After uniformly placing the toner 0.300 g to 0.320 g on a 10 mm width on a soaking roller having a critical surface tension of 18.3 mN / m, the soaking roller is heated to a predetermined temperature and rotated. The cleaning state of the surface of the temperature-uniforming roller was observed by bringing it into contact with the rotationally driven brush roller. Other experimental conditions are as follows. Table 2 shows the observation results.
Linear speed of soaking roller: 310 mm / sec
Brush roller linear velocity: 372 mm / sec
Contact force between the temperature-uniforming roller and the brush roller: The contact force was set to 3.5N to 3.7N by a torsion coil spring.
Brush density of brush roller: 15470 / inch ²
Brush fiber height: 1.6 mm
Soaking roller surface temperature: The soaking roller temperature was controlled by a non-contact temperature detecting means.

As shown in Table 2, in Examples 1 to 3, in which the surface temperature of the soaking roller is a temperature range in which the storage elastic modulus G ′ (Pa) of the toner falls within a predetermined range when the deposit is toner. The cleaning state of the surface of the heating roller was at a level causing no problem in actual use.
On the other hand, in Comparative Example 1 where the surface temperature of the soaking roller was less than the temperature at which the storage elastic modulus G ′ of the toner reached a predetermined value (Pa), the wax component was insufficiently oozed due to insufficient melting of the toner. The releasability of the toner from the soaking roller did not increase, and scraping with the brush roller became insufficient. On the other hand, in Comparative Example 2 in which the surface temperature of the temperature-uniforming roller exceeds the temperature at which the storage elastic modulus G ′ of the toner reaches a predetermined value (Pa), the adhesive force on the surface of the temperature-uniforming roller 7 is increased due to overmelting of the toner. However, cohesive failure occurred in the toner, and the front end side of the toner was scraped off by the brush roller, but the toner base side (heat equalizing roller side) remained on the temperature equalizing roller, resulting in poor cleaning.

(Examples 4, 5 and Comparative Examples 3 to 6)
After 0.30 g to 0.322 g of a mixture of 50 wt% toner and 50 wt% paper powder (calcium carbonate) was uniformly placed on a soaking roller having a critical surface tension of 18.3 mN / m on a 10 mm width, The heating roller was heated to a predetermined temperature and rotated, and brought into contact with the brush roller that was driven to rotate, and the cleaning state of the temperature-uniforming roller surface was observed. Other experimental conditions are the same as described above. Table 3 shows the observation results.

As shown in Table 3, even when the deposit is a mixture of toner and calcium carbonate, the surface temperature of the soaking roller is a temperature range in which the storage elastic modulus G ′ (Pa) of the toner falls within a predetermined range. In Examples 4 and 5, the cleaning state on the surface of the temperature-uniforming roller was at a level causing no problem in practical use.
On the other hand, in Comparative Examples 3 to 5, in which the surface temperature of the soaking roller was less than the temperature at which the storage elastic modulus G ′ of the toner reached a predetermined value (Pa), the wax component exudes due to insufficient melting of the toner. Due to the shortage, the releasability of the toner from the temperature-uniforming roller was not improved, and scraping with the brush roller was insufficient. On the other hand, in Comparative Example 6 in which the surface temperature of the temperature equalizing roller exceeds the temperature at which the storage elastic modulus G ′ of the toner becomes a predetermined value (Pa), the adhesive force on the surface of the temperature equalizing roller 7 increases due to overmelting of the toner. Although the cohesive failure occurred in the mixture and the front end side of the mixture was scraped off by the brush roller, the base side of the mixture (the soaking roller side) remained on the soaking roller, resulting in poor cleaning.

  Further, the cleaning state of the soaking roller was observed in the same manner as in Examples 1 to 5 and Comparative Examples 1 to 6 except that a soaking roller having a critical surface tension of 14 mN / m was used. The observation result similar to -5 and Comparative Examples 1-6 was obtained.

4 Fixing roller (fixing rotating body)
5 Pressure roller (Pressure rotating body)
6 Magnetic flux generator (first heating means)
7 Soaking roller 8 Brush roller P Paper (member to be transferred)
T fixing device 72 release layer 73 halogen heater (second heating means)

Claims (5)

A fixing rotator, first heating means for heating the fixing rotator, a pressure rotator that presses against the fixing rotator to form a nip portion, and a surface of the pressure rotator, A temperature-uniforming roller that makes the temperature distribution in the rotation axis direction uniform, a second heating unit that heats the temperature-uniforming roller, different from the first heating unit, and a surface of the temperature-uniforming roller. A fixing device that includes a brush roller for cleaning, and that melts and fixes the toner image to the transfer member by passing the nip portion through the transfer member having an unfixed image formed of toner on one side thereof. In
The temperature of the soaking roller is not less than the temperature at which the storage elastic modulus G ′ of the toner is 3.12 × 10 ⁴ Pa and not more than 9.16 × 10 ² Pa , and
The storage elastic modulus G ′ of the mixture of 50 wt% toner and 50 wt% calcium carbonate is heated to a temperature equal to or higher than 5.74 × 10 ⁴ Pa, and the surface of the soaking roller is cleaned with the brush roller. A fixing device. The brush roller and the temperature-uniforming roller are contactable / separable,
In the temperature raising operation for heating the fixing rotator to a predetermined fixing temperature and in the fixing operation for heating and pressurizing the toner image to melt and fix the toner image on the transfer member, the soaking roller and the pressure rotator are contacting the temperature-uniforming roller is driven to rotate by the rotation of the pressure rotating body, the fixing device according to claim 1, wherein the spaced apart from said temperature-uniforming roller and said brush roller. The soaking roller and the pressure rotator can be freely contacted and separated,
The brush roller and the temperature-uniforming roller can be contacted / separated freely,
2. When cleaning the soaking roller by the brush roller, the soaking roller and the pressure rotator are separated from each other, and the brush roller and the soaking roller are in contact with each other and driven to rotate. Or the fixing device according to 2 ; The brush roller comprises a plurality of heat-resistant resin fibers on the surface,
It said refractory planted bristle density of the resin fibers 7740 present / inch ² or more 65000 present / inch ² or less, the fiber diameter of 40μm or 500μm or less, the length is 1.8mm or less the range of 1.5mm claims 1-3 The fixing device according to any one of the above. The temperature-uniforming roller fixing device according to any one of claims 1-4 critical surface tension and has a release layer below 14 mN / m or more 18 mN / m on the surface.