JP2015191117A - fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of improving a cleaning property of toner when stagnation of recording materials occurs.SOLUTION: A fixing device includes: first and second rotation bodies which fix a toner image on a recording material by a fixing nip part; and toner recovery means for recovering toner adhered on the first rotation body, and executes a return cleaning operation by the toner recovery means after performing a process of removing the stagnated recording material when stagnation of the recording materials occurs. The fixing device includes temperature control means which temperature-controls at least one of the first rotation body and the toner recovery means when performing the return cleaning operation, and sets the temperature of the toner recovery means to be higher than a first temperature in which a toner viscosity is equal to or less than 1500 Pa s and lower than a second temperature in which the toner viscosity is equal to or less than 50 Pa s.

Description

  The present invention relates to a fixing device used in an image forming apparatus such as a copying machine or a laser beam printer, and more particularly to a fixing device that can collect residual toner on a fixing member.

  Conventionally, an image forming apparatus that transfers a toner image formed on an image carrier such as a photosensitive member or an intermediate transfer member onto a recording material by a transfer unit, and heat-fixes the toner image transferred onto the recording material with a fixing device. It has been known.

  In the fixing device of the heat fixing system, the optimum amount of heat for melting the toner image on the recording material varies depending on the thickness, basis weight, etc. of the recording material. Therefore, the optimum amount of heat is obtained by adjusting the temperature of the fixing member. However, when the toner image on the recording material has an image pattern close to isolated dots, the amount of heat is excessive and the toner is offset onto the fixing member. As a result, image smearing due to offset toner occurs.

  As a countermeasure, there has been proposed a fixing device having a mechanism for cleaning the offset toner on the fixing member by bringing a cleaning web for cleaning and removing residual toner on the fixing member into contact with the fixing member (Patent Document 1). ).

  In addition, there is a problem that the fixing member is damaged by a cleaning web or a foreign matter sandwiched between the cleaning webs, and the image becomes healthy as a streak. As a countermeasure, a fixing device having a configuration in which another cleaning member is interposed between the cleaning web and the fixing member has been proposed (Patent Document 2). In Patent Document 2, the cleaning member collects offset toner on the fixing member, and the collected toner on the cleaning member is cleaned by a cleaning web.

  In addition, in order to prevent the cleaning web and the cleaning member from sticking, a cleaning web provided with a separation mechanism has been proposed. In this case, the cleaning member is always brought into contact with the fixing member, and the cleaning web is brought into contact mainly during image formation.

JP-A-6-194986 JP 2004-212409 A

  However, during an emergency stop of the apparatus due to a jam, the recording material remains in the fixing nip portion formed by the fixing member for a long time, and the amount of toner offset on the cleaning member increases more than usual. As a result, when the temperature of the cleaning member is too high, a large amount of offset toner on the cleaning member is melted, and then it is rotated between the fixing member and the cleaning member, and finally backflows and adheres again onto the fixing member ( Re-offset). When the re-offset occurs, the recording material and other members that come into contact with the fixing member are stained, and a streak-like image defect occurs.

  However, if the temperature of the cleaning member is lowered too much in order to prevent the re-offset, the offset toner on the cleaning member will not be sufficiently melted and deformed, and the recoverability by the cleaning web will be reduced.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device that can improve toner cleaning properties when a recording material stays.

  In order to achieve the above object, a fixing device according to the present invention includes first and second rotating bodies that fix a toner image on a recording material at a fixing nip portion, and toner attached to the first rotating body. And a toner collecting unit that collects the toner, and when the recording material stays, a fixing device that performs a return cleaning operation by the toner collecting unit after performing a process of removing the staying recording material. During the return cleaning operation, the temperature of at least one of the first rotating body and the toner collecting unit is controlled, and the temperature of the toner collecting unit is higher than the first temperature at which the toner viscosity is 1500 Pa · s or less, and It has a temperature control means for making the toner viscosity lower than the second temperature at which the viscosity is 50 Pa · s or less.

  Another fixing device according to the present invention includes a first rotating body that fixes a toner image on a recording material at a fixing nip portion, a counter body that faces the first rotating body, and the first rotation. A toner collecting means for collecting the toner adhering to the body, and when the recording material stays, after the processing to remove the staying recording material is performed, a return cleaning operation is performed by the toner collecting means In the fixing device, the temperature of at least one of the first rotating body and the toner collecting unit is controlled during the return cleaning operation, and the temperature of the toner collecting unit is such that the toner viscosity is 1500 Pa · s or less. And a temperature control means for making the toner viscosity lower than a second temperature at which the toner viscosity is 50 Pa · s or less.

  According to the present invention, it is possible to provide a fixing device capable of improving the cleaning property of the toner when the recording material stays.

3 is a flowchart illustrating a cleaning operation of the fixing device according to the first embodiment of the present invention. 1 is a schematic configuration diagram of an image forming apparatus equipped with a fixing device according to an embodiment of the present invention. 1 is a configuration explanatory diagram of a fixing device according to a first embodiment. FIG. It is a graph which shows a toner melt viscosity characteristic. FIG. 6 is a schematic diagram showing temperature changes of the fixing roller 40 and the collection roller 62 in the first embodiment. FIG. 3 is a layout diagram of recording material detection sensors of the fixing device according to the first embodiment. 6 is a flowchart illustrating a cleaning operation of a fixing device according to a second embodiment. FIG. 6 is a configuration explanatory diagram of a fixing device according to a second embodiment. 10 is a flowchart illustrating a cleaning operation of a fixing device according to a third embodiment. FIG. 10 is a configuration explanatory diagram of a fixing device according to a third embodiment. It is a schematic diagram explaining the effect of 3rd Embodiment. It is a figure which shows an example of the collection | recovery property to a cleaning web, and the retransfer evaluation result to a fixing roller.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

<< First Embodiment >>
(Image forming device)
FIG. 2 is a schematic configuration diagram of an image forming apparatus equipped with the fixing device according to the embodiment of the present invention. In the apparatus shown in FIG. 2, first, second, third, and fourth image forming portions Pa, Pb, Pc, and Pd are provided. Different color toner images are formed through the latent image, development, and transfer processes, and operate as follows in response to an image formation start instruction from the CPU.

  The image forming units Pa, Pb, Pc, and Pd include photosensitive drums 3a, 3b, 3c, and 3d, which are the respective image carriers, and the toner images of the respective colors are formed on the photosensitive drums 3a, 3b, 3c, and 3d. It is formed. An intermediate transfer member 20 is installed adjacent to each photosensitive drum 3a, 3b, 3c, 3d. The toner images of the respective colors formed on the photosensitive drums 3a, 3b, 3c, and 3d are primarily transferred onto the intermediate transfer body 20 and transferred onto the recording material P at the secondary transfer portion. The recording material P onto which the toner image has been transferred is fixed to the toner image by heating and pressurizing at the fixing unit 9 and then discharged out of the apparatus as a recorded image.

  Drum chargers 2a, 2b, 2c, and 2d, developing devices 1a, 1b, 1c, and 1d, primary transfer chargers 6a, 6b, 6c, and 6d, and a cleaner are disposed on the outer periphery of the photosensitive drums 3a, 3b, 3c, and 3d, respectively. 4a, 4b, 4c, 4d are provided. Laser scanners 5a, 5b, 5c, and 5d are installed above the apparatus, and a light source device and a polygon mirror (not shown) are provided in the laser scanners 5a, 5b, 5c, and 5d.

  The laser light emitted from the light source device is scanned by rotating the polygon mirror, the light beam of the scanning light is deflected by the reflection mirror, and is condensed on the buses of the photosensitive drums 3a, 3b, 3c, and 3d by the fθ lens (not shown). And expose. By this exposure, latent images corresponding to the image signals are formed on the photosensitive drums 3a, 3b, 3c, and 3d. The latent image operation by the laser scanner is performed with an image write signal from the CPU as a starting point.

  The developing devices 1a, 1b, 1c, and 1d are filled with a predetermined amount of cyan, magenta, yellow, and black toners, respectively, as developers. The developing devices 1a, 1b, 1c, and 1d develop the latent images on the photosensitive drums 3a, 3b, 3c, and 3d, respectively, and visualize them as cyan toner images, magenta toner images, yellow toner images, and black toner images.

  Here, the intermediate transfer member 20 is rotationally driven at the same peripheral speed as the photosensitive drums 3a, 3b, 3c, and 3d in the direction of the arrow. Then, the yellow toner image of the first color formed and supported on the photosensitive drum 3 a is intermediately transferred to the outer peripheral surface of the intermediate transfer body 20 in the process of passing through the nip portion between the photosensitive drum 3 a and the intermediate transfer body 20. Go. More specifically, intermediate transfer is performed on the outer peripheral surface of the intermediate transfer body 20 by an electric field and pressure formed by a primary transfer bias applied to the intermediate transfer body 20.

  Reference numeral 11 denotes a secondary transfer roller, which corresponds to the intermediate transfer body 20 and is provided in parallel and in contact with the lower surface portion. A desired secondary transfer bias is applied to the secondary transfer roller 11 by a secondary transfer bias source. Transfer of the composite color toner image superimposed and transferred onto the intermediate transfer member 20 to the recording material P is performed by this secondary transfer bias.

  That is, the recording material P is fed at a predetermined timing to the contact nip between the intermediate transfer body 20 and the secondary transfer roller 11 through the registration roller 12 and the pre-transfer guide from the paper feeding cassette 10, and simultaneously the secondary transfer. A bias is applied from a bias power source to perform secondary transfer.

  Similarly, the second color magenta toner image, the third color cyan toner image, and the fourth color black toner image are sequentially superimposed and transferred onto the intermediate transfer body 20, and a composite color toner image corresponding to the target color image is obtained. Is formed. The composite color toner image is formed leaving a certain margin from the four side edges of the transfer material P.

  After the primary transfer, the photosensitive drums 3a, 3b, 3c, and 3d are cleaned and removed of the transfer residual toner by the respective cleaners 4a, 4b, 4c, and 4d, and are subsequently prepared for forming the next latent image. The toner and other foreign matters remaining on the intermediate transfer member 20 are wiped by bringing the transfer cleaning web (nonwoven fabric) 30 into contact with the surface of the intermediate transfer member 20. The recording material P that has received the transfer of the toner image is sequentially introduced into the fixing device 9 and fixed by applying heat and pressure to the recording material P.

  In the case of duplex printing, the recording material P fed from the paper feed cassette 10 passes through the registration roller 12, the pre-transfer guide, and the contact nip between the intermediate transfer body 20 and the secondary transfer roller 11, and is fixed on one side by the fixing 9. After the fixing, the flapper 110 guides the reversal path 111. Thereafter, the recording material P is reversed by the reversing roller 112 and guided to the double-sided path 113.

  Then, the recording material P again passes through the registration roller 12, the pre-transfer guide, and the contact nip between the intermediate transfer body 20 and the secondary transfer roller 11, the second surface is transferred, and both surfaces are fixed by the fixing device 9. Note that the surface flapper 110 is switched while the recording material is forming a double-sided image, and the recording material P fixed on both sides is discharged out of the apparatus as a recorded image.

(Recording material retention)
As described above, the recording material may not be smoothly conveyed and the recording material may stay (so-called jam). When the recording material stays, the toner collecting unit performs a process of removing the staying recording material and then performs a warm-up operation on the fixing roller (first rotating body) for re-operation. A return cleaning operation is performed by the (cleaning mechanism). This will be described in detail later.

  As staying detection means for detecting staying of the recording material before and after the fixing nip (detailed later), a pre-fixing sensor 110, a post-fixing sensor 111, an inner discharge sensor 112, an outer discharge sensor 113, and a discharge port in FIG. A sensor 114 is disposed in the conveyance path of the recording material P. Thus, the stay detection means is specifically a recording material detection sensor (presence detection means) for detecting the presence or absence of the recording material P.

  If the recording material P is present, each sensor is turned on. If it is in the state shown in FIG. 6, it is determined that all the sensors are OFF and there is no recording material P. The CPU monitors whether or not each of the fed recording materials P is jammed by a plurality of detection sensors (not shown) on the conveyance path including 110, 111, 112, 113, and 114.

(Fixing device)
FIG. 3 is an explanatory diagram of a configuration of the fixing device 9 according to the present embodiment. The unfixed toner image T secondarily transferred onto the recording material is formed by a fixing roller (heating fixing member) 40 and a pressure roller (pressure member) 41 as a first rotating body that is brought into contact with the image surface. The recording material P is nipped and conveyed by the fixing nip portion and fixed on the recording material P. In the fixing device 9, the pressure roller 41 is pressed against the fixing roller 40 with a total pressure of 784 N (about 80 kg) to form a fixing nip portion.

  The fixing roller 40 is configured to have a diameter of 80 mm by disposing an elastic layer having a thickness of 3 mm on the outer peripheral surface of an aluminum cylindrical cored bar. This elastic layer is an HTV (high temperature vulcanization type) silicon rubber layer, and a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene, which is a release layer in contact with the image surface, on the outer peripheral surface of the HTV silicon rubber layer. (Hereinafter, PFA) is covered with a tube made of a main material.

   The pressure roller 41 is configured to have a diameter of 60 mm by disposing an elastic layer having a thickness of 1 mm on the outer peripheral surface of an aluminum cylinder core. This elastic layer is an HTV silicon rubber layer like the fixing roller 40, and its surface layer is covered with a PFA tube.

  Halogen heaters 40a and 41a for heating the rollers from the inside are arranged at the rotation centers of the fixing roller 40 and the pressure roller 41 so as not to rotate. The halogen heaters 40a and 41a are turned on / off by the CPU of the image forming apparatus so as to reach a predetermined temperature based on the output results of the temperature detecting elements 42a (first temperature detecting means) and 42b for detecting the roller surface temperature. Be controlled. Here, the target temperature adjustment temperature at the time of image formation of the fixing roller 40 is 170 ° C., and the target temperature adjustment temperature of the pressure roller 41 is 100 ° C.

  Further, both the fixing roller 40 and the pressure roller 41 are supported by ball bearings at both ends and are rotatable. The fixing roller 40 and the pressure roller 41 have gears fixed to one shaft end connected to each other by a gear mechanism (not shown) and are driven to rotate integrally by a drive system (not shown) in the direction of the arrow. Rotate.

(Fixing roller cleaning mechanism)
In this embodiment, as shown in FIG. 3, as a cleaning mechanism 60 as a toner collecting unit that collects toner attached to the fixing roller 40, a collecting roller 62 that contacts the fixing roller and a cleaning web 61 that contacts the collecting roller. And have. Here, the cleaning web 61 is provided so as to be able to come into contact with and separate from the collection roller 62, and is displaced between the contact position and the separation position. When the recording material stays, the contact position comes into contact with the collection roller. Placed in.

  The collecting roller 62 having a diameter of 20 mm is always installed so as to rotate in contact with the surface of the fixing roller 40. When the toner adheres to the surface of the fixing roller 40 during fixing, the collecting roller 62 collects the toner. The collection roller 62 is a SUS hollow roller (hollow rotating body). By using a hollow roller, the heat transfer performance can be improved, and the follow-up performance of the collection roller temperature with respect to the fixing roller can be improved. It becomes easy. The reason why the collecting roller 62 is always in contact with the fixing roller 40 is to collect the deposit on the surface of the fixing roller 40 other than during image formation.

  In FIG. 3, the cleaning web 61 and the web roller 63 for supporting the cleaning web 61 and pressing it against the collection roller 62 can be displaced in the direction of the arrow 64 between the contact position and the separation position.

  Specifically, in accordance with an instruction from the CPU of the image forming apparatus, a contact / separation mechanism (not shown) is operated to perform contact / separation (detachment). In the contact state, the collecting roller 62 is pressed with a force of about 40 N, and the toner collected from the fixing roller 40 on the collecting roller 62 is collected (cleaned) by the cleaning web 61. The cleaning web 61 in contact with the collection roller 62 is wound in the conveyance direction indicated by the arrow 59, and a new surface without toner adhesion is always supplied to the surface in contact with the collection roller 62.

  The collection roller 62 is supported by a ball bearing supported so as to be displaceable in the direction of the fixing roller 40, and is rotatable. The collecting roller 62 is always in contact with the fixing roller 40, and presses the fixing roller 40 with a pressure of about 10N by its own weight when the web roller 63 is separated. Further, in the contact state of the web roller 63, the fixing roller 40 is pressed with a force of about 50 N by applying the pressing force 40 N of the web roller 63, and driving is transmitted from the fixing roller 40 as the fixing roller 40 rotates. Rotate.

  In the jam recovery cleaning operation in which a large amount of toner is assumed to adhere to the fixing roller 40, the temperature of the recovery roller 62 is higher than the toner melting temperature (first temperature), and the re-offset is a temperature at which the toner re-adheres. It is made lower than the temperature (second temperature). In this way, the target temperature Ta of the fixing roller 40 is controlled at a temperature adjustment temperature different from the image forming temperature.

  The toner melting temperature (first temperature) here is a temperature at which the toner viscosity η becomes η0 = 1500 Pa · s or less. At the first temperature, the toner recovered by the recovery roller 62 and once cooled can be sufficiently deformed to ensure recoverability from the recovery roller 62 to the cleaning web 61. The re-offset temperature (second temperature) is a temperature at which the toner viscosity η becomes η0 = 50 Pa · s or less. At the second temperature, the toner on the collection roller 62 further melts and spreads and starts to be offset (reattached) to the fixing roller 40. The first temperature and the second temperature can be set by the following measurement and verification.

  FIG. 4 is a graph of melt viscosity characteristics obtained by measuring the toner of this embodiment with a flow tester. The toner melt viscosity was measured with a flow tester using a flow tester CFT-500D (manufactured by Shimadzu Corporation) according to the operation manual of the apparatus under the following conditions. In this embodiment, a polyester resin is used as the base (binder) of the color toner. Further, a pulverization method was used as a manufacturing method of the color toner. The toner production method may be a suspension polymerization method, an interfacial polymerization method, a dispersion polymerization method, or a polymerization method, and the toner components and the production method are not limited to these.

Sample: 1.0 g of toner is weighed and molded by pressing it with a pressure molding machine having a diameter of 1 cm at a load of 20 kN for 1 minute.
-Die hole diameter: 0.5 mm (130 ° C or higher) 1.0 mm (less than 130 ° C)
-Die length: 1.0mm
・ Cylinder pressure: 9.807 × 105 (Pa)
Measurement mode: Temperature rising method Temperature rising rate: 10 ° C./min (130 ° C. or higher) 4.0 ° C./min (less than 130 ° C.)
By the above method, the viscosity (Pa · s) of the toner at 50 ° C. to 200 ° C. was measured. As can be seen from FIG. 4, by increasing the temperature, the melt viscosity of the toner decreases and the toner is easily deformed. FIG. 4 shows that the temperature at which the melt viscosity is about 1500 Pa · s or less is 120 ° C. or more. Therefore, the toner melting temperature (first temperature) in this embodiment is set to 120 ° C. It was also found that the temperature at which the melt viscosity was about 50 Pa · s or lower was 160 ° C. or higher. Therefore, the toner re-offset temperature (second temperature) in this embodiment is set to 160 ° C.

Whether the set toner melting temperature (first temperature) is appropriate is verified by the following method.
To the collection roller 62, toner having a maximum loading amount on the paper (1.2 mg / cm 2 in this embodiment) is adhered. Next, the recovery roller temperature was changed in increments of 10 ° C. from 100 ° C. to 180 ° C., and the recoverability of the toner onto the cleaning web 61 was evaluated. In this embodiment, a SUS hollow metal roller incorporating a halogen heater as a heat supply source to the collection roller 62 is brought into contact with the collection roller 62.

  The heat supply method is not limited to this. The toner recoverability is determined by measuring the concentration of toner collected on the web 61 after the cleaning operation with a reflection densitometer “X-Rite” (trade name, manufactured by X-Rite), and the density is D0 = 1.0 or more. In this case, it was determined that the recoverability was OK. The determination reference density is not limited to D0 = 1.0. However, when a non-woven cloth web is used, a density of about 80% or more with respect to the on-paper toner density Dmax when the paper is fixed with the maximum applied amount. It is desirable to be based on

  FIG. 12 shows the evaluation result of the toner recoverability with respect to the recovery roller temperature. From FIG. 12, it was verified that when the temperature of the collection roller 62 is 120 ° C. or higher, the toner is sufficiently deformed and collected from the collection roller 62 to the cleaning web 61. Therefore, it was found that 120 ° C. is appropriate as the toner melting temperature (first temperature) in this embodiment.

  Next, whether the set toner re-offset temperature (second temperature) is appropriate is verified by the following method. The toner of the maximum loading amount on the paper (in this embodiment, 1.2 mg / cm 2) is adhered to the collection roller 62. Next, the recovery roller temperature was changed in increments of 10 ° C. from 100 ° C. to 180 ° C., and the amount of re-offset (reattachment) of toner to the fixing roller 40 rotated by heating was evaluated. The presence / absence of re-offset was determined by peeling the surface of the fixing roller 40 after the 20s heating and rotating operation with a peeling tape (Sumitomo 3M: 3099) and checking for streaks.

  The heating / rotating operation time is not limited to the above, but within the time that the fixing roller 40 rotates more than one turn and within the time that the temperature rise above the target value does not occur in the fixing roller and the collecting roller due to long-time heating. I just need it. The heating rotation speed is set to a rotation speed at which the power is turned on and the fixing device starts to be heated and rotated. Further, the temperature adjustment temperature of the fixing roller 40 is set to the highest temperature adjustment range of use. In this embodiment, the temperature is set to 180 ° C.

  FIG. 12 shows the evaluation result of re-offset (reattachment) with respect to the collection roller temperature. From FIG. 12, it was found that re-offset (reattachment) occurs when the temperature of the collection roller 62 is 160 ° C. or higher. Therefore, it was found that 160 ° C. is appropriate as the re-offset temperature (second temperature) in the present embodiment.

  From the above, the temperature of the collection roller 62 in this embodiment is higher than the toner melting temperature (first temperature) and lower than the re-offset temperature (second temperature), and is 120 ° C. or higher and lower than 160 ° C. desirable.

(Jam-return cleaning flowchart)
FIG. 1 is a flowchart illustrating a jam recovery cleaning operation of the fixing device according to the present exemplary embodiment. In the present embodiment, after the jam processing, the jam recovery cleaning operation is performed before the fixing device performs the warm-up operation.

  In S101, the CPU determines whether or not a jam has occurred in the image forming apparatus. If a jam has occurred in the image forming apparatus, the process proceeds to S102. In S102, the CPU determines whether there is a history of remaining paper in the fixing device. The CPU checks ON / OFF of the recording material P presence / absence detection sensors 110, 111, 112, 113, and 114. If any of the sensors is OFF, the paper jams before and after the fixing nip portion due to a jam. It is determined that there is a remaining history, and the process proceeds to S103.

  In S102, when the jammed transfer material P is applied to the pre-fixing sensor 110 and the post-fixing sensor 111, the temperature of the unfixed toner image on the recording material P decreases while the recording material P is being removed by the user. The fixing roller 40 may be offset.

  Further, when the jammed recording material P is applied to the post-fixing sensor 111 and the outer paper discharge sensor 113, the rear end portion of the recording material P still remains in the fixing nip formed by the fixing roller 40 and the pressure roller 41. Similarly, there is a possibility that the unfixed toner image is offset on the fixing roller 40. In these cases, the process proceeds to S103. In S103, the CPU controls to start the jam recovery cleaning of the fixing device 9.

  In S104, temperature detection is first performed by the surface temperature detection element 42a of the fixing roller 40, and it is determined whether or not the temperature of the fixing roller 40 has been lowered. In the present embodiment, when the detection temperature T1 of the temperature detection element 42a is less than 50 ° C., it is determined that the fixing roller temperature has been lowered. If it is determined that the temperature is in the state A, the process proceeds to S105. If it is determined that the temperature is not lowered, the process proceeds to S106.

  In S105, the target temperature Ta is set as the temperature control of the fixing roller 40, and the ON / OFF control of the halogen heater 40a based on the detected temperature of the temperature detecting element 42a is started. The target temperature Ta in S105 is set to a temperature corresponding to the state A in which the temperature is lowered (lower than the predetermined temperature).

  In S106, the target temperature Ta is set as the temperature control of the fixing roller 40, and the ON / OFF control of the halogen heater 40a based on the detected temperature of the temperature detecting element 42a is started. The target temperature Ta in S105 is set to a temperature corresponding to the state B that is equal to or higher than a predetermined temperature at which the temperature has not decreased.

  In S105 and S106, in order to keep the temperature of the collection roller 62 always higher than the first temperature and lower than the second temperature at 120 ° C. or higher and lower than 160 ° C., the fixing roller 40 in the state A The target temperature Ta needs to be set higher than the target temperature in the state B. In the present embodiment, Ta = 180 ° C. is set in the state A of S105, and Ta = 160 ° C. is set in the state B of S106.

  In S107 and 108, the CPU determines whether or not the detected temperature T1 of the temperature detecting element 42a has reached the target temperature Ta. If T1 ≧ Ta, the process proceeds to S109. In S109, the cleaning web feeding operation is started and the measurement of the cleaning time t is started. In S110, rotation of the fixing roller 40 is started. In S <b> 111, the web roller 63 is pressed against the collection roller 62 and the cleaning web 61 is brought into contact with the collection roller 62 (attachment operation).

  In addition, the operation | movement of S109-S111 in this embodiment is performed substantially simultaneously. The operations of S109 to S111 may be switched in order, for example, the web roller 63 may be pressed against the collection roller 62 and then the cleaning web feeding operation may be started.

  In S112, the CPU determines whether or not the cleaning time t is t> t1 with respect to the predetermined time t1. If it is detected that t> t1, the process proceeds to S113. If t> t1, the cleaning operation up to S111 is continued. In S113, the web feeding operation is stopped. In S <b> 114, the web roller 63 is separated from the collection roller 62. In S115, the jam recovery cleaning is terminated, and a normal warm-up operation is performed.

  FIG. 5 is a graph showing changes in the surface temperature of the fixing roller 40 and the recovery roller 62 during the jam return cleaning. The surface temperature of the collection roller 62 increases following the increase in the surface temperature of the fixing roller 40. From FIG. 5, it can be seen that in the state A in which the fixing roller temperature is lowered, it takes longer to raise the temperature of the recovery roller 62 than in the state B in which the fixing roller temperature is not lowered. This is because, in the state A in which the fixing roller temperature is lowered, the recovery roller temperature is similarly decreased, so that the heat supply to the surface of the recovery roller becomes difficult to follow the fixing roller.

  Therefore, even when the surface temperature of the fixing roller 40 is the same 180 ° C., the surface temperature of the recovery roller 41 is different between the state A in which the fixing roller temperature is lowered and the state B in which the fixing roller temperature is not lowered. As a result, the temperature of the collection roller 62 does not fall within the range of 120 ° C. or more and less than 160 ° C., and the cleaning performance is deteriorated.

  For example, in the state A, if the target temperature Ta as the temperature control of the fixing roller 40 is set to 160 ° C., the temperature of the collecting roller 62 at this time is about 90 ° C. As a result, the toner is insufficiently melted, the recoverability by the cleaning web 61 is lowered, and the offset toner remains on the recovery roller 62. In the state B, if the target temperature Ta for controlling the temperature of the fixing roller 40 is set to 180 ° C., the temperature of the collecting roller 62 at this time becomes about 160 ° C., and a re-offset to the fixing roller 40 occurs. End up.

  Therefore, in the state A in which the fixing roller temperature is lowered during the jam recovery cleaning, the target temperature of the fixing roller 40 is set to 180 ° C. As a result, the recovery roller temperature during cleaning could be kept at 120 ° C. or higher and lower than 160 ° C.

  Further, when the fixing roller temperature was not lowered during the jam recovery cleaning, the target temperature of the fixing roller 40 was set to 160 ° C. As a result, the recovery roller temperature during cleaning could be kept at 120 ° C. or higher and lower than 160 ° C.

  From the above, it is determined whether or not the fixing roller temperature has decreased during jam recovery cleaning, and the optimum fixing roller temperature control temperature is set, so that the recovery roller temperature is higher than the first temperature described above, The temperature is kept at 120 ° C. or higher and lower than 160 ° C. as a temperature lower than 2. As a result, good cleaning properties could be secured without re-offsetting the toner to the fixing member.

  Note that the target temperature of the fixing roller at the time of jam recovery cleaning used in the present embodiment is not limited to this, and is appropriately set according to the melting characteristics of the toner, the thermal characteristics of the members of the fixing roller and the recovery roller, and the like. It is. In this embodiment, the fixing roller target temperature during the jam recovery cleaning is set to be different from the fixing roller target temperature (170 ° C.) during the normal image forming operation (180 ° C. in state A, 160 ° C. in state B). It may be set to the same target temperature.

<< Second Embodiment >>
FIG. 8 is a diagram illustrating the configuration of the fixing device according to the present embodiment. Members having the same configuration as in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the present embodiment, in order to perform more accurate collection roller temperature control, a temperature detection element 65 for detecting the temperature of the collection roller 62 is provided on the surface of the collection roller 62 as a second temperature detection unit. Further, the surface temperature of the recovery roller 62 detected by the temperature detection element 65 is used as the target temperature in the OFFON control of the halogen heater 40a as temperature control of the fixing roller at the time of jam return cleaning.

  FIG. 7 is a flowchart illustrating a jam recovery cleaning operation of the fixing device according to the present exemplary embodiment. In this embodiment, the temperature T of the collection roller 62 is constantly monitored by the temperature sensor 65. Since S201 to S203 are the same as S101 to S103 in the first embodiment, a description thereof will be omitted.

  In S204, the target temperature Tc of the recovery roller 62 is set, and ON / OFF control of the halogen heater 40a is started as temperature control of the fixing roller 40 based on the detected temperature T of the temperature detecting element 65. In S204, the target temperature Tc of the recovery roller 62 is set to a temperature in a temperature range of 120 ° C. or more and less than 160 ° C. as a temperature higher than the first temperature and lower than the second temperature described in the first embodiment. Here, considering that the temperature tracking of the collection roller 62 with respect to the fixing roller 40 is slightly delayed, in this embodiment, a slightly lower temperature is set to Tc = 130 ° C.

  In S205, the CPU determines whether or not the detected temperature T of the temperature detecting element 65 has reached the target temperature Tc. If T ≧ Tc, the process proceeds to S206. If T <Tc, the temperature control in S204 is continued. Since S206 to S212 are the same as S109 to S115, a description thereof will be omitted.

  As described above, in this embodiment, the surface temperature of the collection roller 62 is directly monitored, and OFFON control of the halogen heater 40a is performed as temperature control of the fixing roller 40 according to the result. For this reason, it is possible to more accurately control the collection roller temperature and to ensure good cleaning properties.

<< Third Embodiment >>
FIG. 10 is a diagram illustrating the configuration of the fixing device according to the present embodiment. In the first and second embodiments, the CPU 150 serving as the temperature control unit controls the temperature of the toner collection unit that collects the toner attached to the fixing roller within a predetermined range when the recording material stays. The temperature of the fixing roller 40 was controlled.

  On the other hand, in this embodiment, an internal heater as a heating member is installed in the collection roller 62, and when the recording material stays, the temperature is controlled as follows. That is, the CPU 150 controls the temperature of the fixing roller and the collecting roller so that the temperature of the toner collecting unit that collects the toner attached to the fixing roller is within a predetermined range (S304 described later). In addition, the same code | symbol is provided to the member with the same structure as 1st, 2nd embodiment, and description is abbreviate | omitted.

  In the first and second embodiments, it is necessary to wait for the recovery roller temperature to rise until the jam return cleaning is started, and the standby time becomes longer. In the present embodiment, as a further improvement, the cleaning time after the jam recovery is shortened.

  In the present embodiment, as in the second embodiment, a temperature sensor 65 that detects the temperature of the collection roller 62 is provided as a second temperature detection unit on the surface of the collection roller 62. Furthermore, in the present embodiment, the collection roller heater 62a, which is a halogen heater that heats the collection roller 62 from the inside, is installed in a non-rotating manner.

  FIG. 9 is a flowchart illustrating a jam recovery cleaning operation of the fixing device according to the present exemplary embodiment. In this embodiment, the temperature T of the collection roller 62 is constantly monitored by the temperature sensor 65. Since S301 to S303 are the same as S101 to S103 in the first embodiment, a description thereof will be omitted.

  In S304, the first target temperature Tc1 of the recovery roller 62 is set, and ON / OFF control of the halogen heater 40a in the fixing roller 40 based on the detected temperature T of the temperature detecting element 65 is started. At the same time, the ON / OFF control of the collection roller heater 62a in the collection roller 62 based on the detected temperature T of the temperature detection element 65 is started.

  In S305, the CPU determines whether or not the detected temperature T of the temperature detecting element 65 has reached the first target temperature Tc1 of the collection roller 62. If T ≧ Tc1, the process proceeds to S306. In S306, a second target temperature Tc2 (a temperature higher than the first target temperature Tc1) of the recovery roller 62 is set, and ON / OFF control of the halogen heater 40a in the fixing roller 40 based on the detected temperature T of the temperature detecting element 65 is started. . Then, the collection roller heater 62a in the collection roller 62 is turned off. This is to prevent excessive supply of heat to the surface of the collection roller 62 and exceeding the re-offset temperature (second temperature).

  Here, the first target temperature Tc1 and the second target temperature Tc2 of the recovery roller 62 are higher than the first temperature described in the second embodiment and lower than the second temperature, and are 120 ° C. or higher and lower than 160 ° C. Set the temperature within the temperature range. Note that the first target temperature Tc1 may be set lower than 120 ° C., and only the second target temperature Tc2 may be set to a temperature in a temperature range of 120 ° C. or more and less than 160 ° C.

  In S307, the CPU determines whether or not the detected temperature T of the temperature detecting element 65 has reached the target temperature Tc2 of the collecting roller 62. If T ≧ Tc2, the process proceeds to S308 where the cleaning web feed operation starts and the cleaning time t count starts. When T <Tc2, the operation of S306 is continued. Since S308 to S314 are the same as S109 to S115 in the first embodiment, further description is omitted.

  FIG. 11 is a graph showing the temperature transition of the collection roller 62 in the present embodiment. As shown in FIG. 11, even when the jam recovery cleaning is started from a state where the temperature of the fixing roller is low, the temperature rise of the collecting roller 61 can be accelerated. As a result, the time required to start cleaning could be shortened from 240 s in the conventional example to 180 s. As described above, in this embodiment, the internal heater is installed on the collection roller 62, so that the cleaning time at the time of jam can be shortened.

(Modification)
Although the preferred embodiments of the present invention have been described in the above-described embodiments, the present invention is not limited to these embodiments, and various modifications are possible within the scope of the gist.

(Modification 1)
In the first and second embodiments, when the recording material stays, the temperature of the fixing roller as the first rotating body is controlled, and the temperature of the toner recovery roller as the toner recovery means is set within a predetermined range. . In the third embodiment, when the recording material stays, the temperature of the fixing roller and the toner collection roller as the first rotating body is controlled to keep the temperature of the toner collection roller within a predetermined range (S304). ). The present invention is not limited to these, and when the stay of the recording material occurs, it is possible to control the temperature of only the toner recovery roller as the toner recovery means so that the temperature of the toner recovery roller is within a predetermined range.

  That is, the present invention controls the temperature of at least one of the first rotating body and the toner collecting means when the recording material stays, so that the temperature of the toner collecting means is higher than the first temperature at which the toner melts. And what is necessary is just to make it lower than 2nd temperature reattached to a 1st rotary body.

(Modification 2)
Further, in the above-described embodiment, the toner collecting unit has the toner collecting roller that contacts the fixing roller as the first rotating body and the cleaning web that contacts the toner collecting roller. Not limited to. In other words, the toner collecting unit may have a cleaning web that contacts the fixing roller as the first rotating body. In this case, it is preferable that the cleaning web that comes into contact with the fixing roller is provided so as to be able to come into contact with and separate from the fixing roller so that the recording material stays in contact with the fixing roller when the recording material stays.

(Modification 3)
In the above-described embodiment, the fixing roller is used as the first rotating body. However, an endless belt serving as a heating rotating body may be used. In this case, the endless belt is provided on the first rotating body, but the endless belt may be provided on both the first rotating body and the second rotating body that form the fixing nip portion.

(Modification 4)
In the above-described embodiment, the case where the rotary roller and the pressure roller (second rotary body) as the pressure body press the fixing roller (first rotary body) has been described. However, the present invention is not limited to this, and the present invention can be similarly applied to a case where a rotating body (second rotating body) as an opposing body is pressed from the fixing roller or the endless belt, not as a pressing body. Here, the opposing body is a member that faces the first rotating body (fixing roller), presses against the first rotating body to form a fixing nip portion, and holds the moving recording material at the fixing nip portion. is there.

(Modification 5)
In the above-described embodiment, the pressure roller (second rotating body) is shown as the facing body facing the fixing roller (first rotating body). However, the present invention is not limited to this and is fixed as the facing body. A flat pad can also be used.

(Modification 6)
In the embodiment described above, the recording paper has been described as the recording material (sheet material). However, the recording material in the present invention is not limited to paper. Generally, a recording material is a sheet-like member on which a toner image is formed by an image forming apparatus. For example, regular or irregular plain paper, cardboard, thin paper, envelope, postcard, seal, resin sheet, OHP sheet, Includes glossy paper. In the embodiment described above, for the sake of convenience, the handling of the recording material (sheet material) P has been described using terms such as an internal paper discharge sensor and an external paper discharge sensor. Is not limited to paper.

(Modification 7)
In the above-described embodiment, the fixing device that fixes an unfixed toner image to a sheet has been described as an example. However, the present invention is not limited to this, and the toner image that is supposedly attached to the sheet is used to improve the gloss of the image. The present invention can be similarly applied to a device for heating and pressing (also called a fixing device in this case).

40..Fixing roller, 41..Pressure roller, 61..Cleaning web, 62..Recovery roller, 150..CPU

Claims (13)

First and second rotating bodies for fixing a toner image on a recording material at a fixing nip;
Toner recovery means for recovering toner adhering to the first rotating body;
Have
A fixing device that performs a return cleaning operation by the toner recovery means after performing a process of removing the staying recording material when the recording material stays,
During the return cleaning operation, the temperature of at least one of the first rotating body and the toner collecting unit is controlled so that the temperature of the toner collecting unit is higher than the first temperature at which the toner viscosity is 1500 Pa · s or less, and the toner A fixing device comprising temperature control means for lowering the viscosity below a second temperature at which the viscosity is 50 Pa · s or less. A first rotating body that fixes a toner image on a recording material at a fixing nip portion, and a counter body that faces the first rotating body;
Toner recovery means for recovering toner adhering to the first rotating body;
Have
A fixing device that performs a return cleaning operation by the toner recovery means after performing a process of removing the staying recording material when the recording material stays,
During the return cleaning operation, the temperature of at least one of the first rotating body and the toner collecting unit is controlled so that the temperature of the toner collecting unit is higher than the first temperature at which the toner viscosity is 1500 Pa · s or less, and the toner A fixing device comprising temperature control means for lowering the viscosity below a second temperature at which the viscosity is 50 Pa · s or less.   The fixing device according to claim 1, wherein the toner collecting unit includes a toner collecting roller that contacts the first rotating body and a cleaning web that contacts the toner collecting roller.   The fixing device according to claim 1, wherein the toner recovery unit includes a cleaning web that contacts the first rotating body.   The fixing device according to claim 3, wherein the cleaning web is displaced between a contact position and a separation position. First temperature detecting means for detecting a surface temperature of the first rotating body;
The said temperature control means controls target temperature as temperature control of a said 1st rotary body based on the output of a said 1st temperature detection means, The any one of Claim 1 thru | or 5 characterized by the above-mentioned. Fixing device. The first rotating body has a first state in which the surface temperature is lower than a predetermined temperature and a second state in which the surface temperature is equal to or higher than the predetermined temperature.
The fixing device according to claim 6, wherein the temperature control unit switches a target temperature of the first rotating body depending on whether the temperature is in the first state or the second state. A second temperature detecting means for detecting the surface temperature of the toner collecting means;
6. The fixing device according to claim 1, wherein the temperature control unit controls the temperature of the first rotating body based on an output of the second temperature detection unit. A second temperature detecting means for detecting the surface temperature of the toner collecting means;
6. The fixing device according to claim 1, wherein the temperature control unit controls the temperature of the toner recovery unit based on an output of the second temperature detection unit.   The fixing device according to claim 9, wherein the toner recovery unit includes a heating member.   The fixing device according to claim 1, further comprising a stay detection unit that detects stay of the recording material in the fixing nip portion.   The fixing device according to claim 1, wherein the first rotating body is formed of an endless belt.   The fixing device according to claim 1, wherein the toner collecting unit is a hollow rotating body.