JP6128412B2 - Fixing device, image forming apparatus, temperature control method for fixing device, program, and recording medium - Google Patents

Description

  The present invention relates to a fixing device provided in an electrophotographic image forming apparatus, an image forming apparatus, a temperature control method for the fixing apparatus, a program, and a recording medium.

  As a fixing device used in an electrophotographic image forming apparatus such as a copying machine or a printer, a heat roller fixing type fixing device is frequently used. The fixing device of the heat roller fixing system includes a roller pair (fixing roller and pressure roller) that are in pressure contact with each other, and the roller is heated by a heating unit including a halogen heater or the like disposed inside or both of the roller pair. After the pair is heated to a predetermined temperature (fixing target temperature), the recording paper on which the unfixed toner image is formed is fed to the pressure contact portion (fixing nip portion) of the roller pair, and is passed through the pressure contact portion. The toner image is fixed by pressure.

  Note that in a fixing device provided in a color image forming apparatus, it is common to use an elastic roller provided with an elastic layer made of silicon rubber or the like on the surface of the fixing roller. By using an elastic roller as the fixing roller, the surface of the fixing roller is elastically deformed according to the unevenness of the unfixed toner image and comes into contact so as to cover the toner image surface. It is possible to perform heat fixing on an unfixed toner image satisfactorily.

  Further, due to the effect of releasing the distortion of the elastic layer at the exit of the fixing nip, it is possible to improve the releasability for color toners that are more likely to be offset than in monochrome.

  Further, since the nip shape of the fixing nip portion is convex upward (on the fixing roller side) (so-called reverse nip shape), it is possible to improve the paper peeling performance without using a peeling means such as a peeling claw. Paper can be peeled off (self-stripping), and image defects caused by the peeling means can be eliminated.

  Further, in such a color fixing apparatus, in order to cope with an increase in process speed (recording material conveyance speed), it is necessary to widen the nip width of the fixing nip portion. There are two methods for widening the nip width: a method of increasing the elastic layer of the fixing roller and a method of increasing the diameter of the fixing roller.

  However, when the process speed is increased in the configuration in which the heating means is provided inside the fixing roller as in the prior art, in the method of increasing the elastic layer of the fixing roller, the thermal conductivity of the elastic layer is low, so There is a problem that heat supply becomes insufficient and the temperature of the surface of the fixing roller is lowered. On the other hand, the method of increasing the diameter of the fixing roller has a problem that the heat capacity of each roller increases, so that the warm-up time becomes longer and the power consumption increases.

  In order to solve such problems, in recent years, a belt fixing type color in which a fixing belt is stretched between a fixing roller and a heating roller, and the fixing roller and the pressure roller are pressed against each other via the fixing belt. Fixing devices have been used.

  This type of belt fixing type fixing device heats a fixing belt having a small heat capacity, so that the warm-up time is short, and it is not necessary to incorporate a heat source such as a halogen lamp in the fixing roller. The elastic layer can be provided thick, and a wide nip width can be ensured.

  In the fixing device of the heat roller fixing method or the belt fixing method as described above, in order to further reduce the warm-up time, the heating member (fixing roller or fixing belt) has a lower heat capacity and heating means for heating the heating member. It is conceivable to increase the output. However, when reducing the heat capacity of the heating member or increasing the output of the heating means, it becomes difficult to control the temperature optimally, and the temperature of the heating member fluctuates in the vicinity of the target temperature and has a large temperature range ( (Temperature ripple) occurs.

  For this reason, as a method for suppressing temperature ripples with a simple control system, Patent Documents 1 to 3 disclose a waveform of electric power supplied to the heating means from the temperature difference between the current temperature and the target temperature and the current temperature transition state. A method is disclosed in which the duty ratio is determined and duty control of energization to the heating means is performed.

  Specifically, in Patent Document 1, a table used for temperature control is selected from a plurality of tables based on the time required for the temperature of the fixing roller to rise to a predetermined temperature difference when the power is turned on. Duty control is performed using the selected table.

  Further, in Patent Document 2, the temperature division is determined from the temperature difference between the current temperature of the heating roller and the target temperature, and duty control is performed according to changes in the current and previous temperature divisions.

  Also, in Patent Document 3, the duty ratio is set to 100% when the recording material passes through according to the change in the conveyance state of the recording material, and the recording from when the recording material passes until the next recording material is conveyed is performed. Between materials, duty ratio is set from a temperature difference and a temperature transition state, and duty control to the heating means is performed.

JP 2000-330418 A JP 2007-3663 A JP 2008-134377 A

  By the way, in a fixing device having a small heat capacity such as a belt fixing method, the temperature of members such as a fixing roller, a fixing belt, and a pressure roller changes rapidly, and may easily change from an optimum state.

  For example, the temperature state of the fixing belt or the fixing roller and the temperature state of the pressure roller may keep a mutually complementary relationship to some extent thermally. In other words, when the temperature of the fixing belt and fixing roller is high, the heat energy required for fixing as a whole does not change significantly even if the temperature of the pressure roller is slightly low, so much heat energy is applied from both sides of the recording paper. Attempts to increase the temperature of the pressure roller may result in excessive heating. Alternatively, if the temperature of the fixing belt or fixing roller is low, the heat energy required for fixing does not change much even if the temperature of the pressure roller is slightly high. If it is too high, excessive heating will result.

  Conversely, if the temperature of some members is too high and the temperature of other members is lowered, thermal energy tends to be insufficient, and heating may be insufficient in the same manner.

In particular, in a small system heat capacity, so easily sensitively undergoes a temperature change due to transfer of thermal energy, Ru if more significantly heated excessively or insufficient heating occurs is Ah.

  As described above, it is necessary to control the heating of the recording paper and the toner image to an optimum state against the temperature change of each member that changes from time to time to prevent image deterioration due to poor fixing or excessive heating.

  However, the methods disclosed in Patent Documents 1 to 3 do not consider the temperature change of each member, and thus cannot control the heating to an optimum state.

  The present invention has been made in view of the above problems, and its purpose is to appropriately set various parameters even if the temperature conditions of each member such as a fixing member, a heating member, and a pressure member change. The fixing device, the image forming apparatus, and the like can set the heating conditions for preventing the image deterioration or change to the better heating conditions to give the maintenance and stability of the fixing performance, It is an object to provide a temperature control method of a fixing device, a program, and a recording medium thereof.

In order to solve the above problems, a first technical means of the present invention includes a fixing member and a pressure member that are rotatably provided, a heating member that heats the fixing member to a target temperature, and a supply to the heating member. A temperature control unit that controls the amount of electric power to be performed, and a paper conveyance control unit that controls the conveyance speed of the recording material inserted between the fixing member and the pressure member, and the recording material is used as the fixing member. A fixing device used in an image forming apparatus that fixes an unfixed image on the recording material to the recording material by heat and pressure by being conveyed while being sandwiched between the pressure members, and the temperature control unit includes: A temperature detection unit for detecting temperatures of the fixing member and the pressure member, a target temperature setting unit for setting a target temperature of the fixing member, and a detection of the target temperature and the fixing member set by the target temperature setting unit Based on temperature and before An output determining unit that determines the amount of power supplied to the heating member, the fixing device, the transition from the Ready standby state of the image forming apparatus to the printing state, at least during the transition from the cooling state to the printing state A plurality of target setting correction tables in which the detected temperature of the pressure member or the fixing member and the conveyance speed of the recording material are associated with each other according to a change in the operation state including the two, the sheet conveyance control unit, Selecting one target setting correction table in accordance with the change in the operating state, and determining the conveyance speed of the recording material from the selected target setting correction table based on the detected temperature of the pressure member or the fixing member; The conveyance speed of the recording material is changed.

According to a second technical means, in the first technical means, the fixing device further includes a cooling fan, and drives the cooling fan in accordance with a detected temperature of the pressure member. is there.

The third technical means includes a fixing device which is the first or second technical means.

A fourth technical means includes a fixing member and a pressure member that are rotatably provided, and a heating member that heats the fixing member to a target temperature, and is inserted between the fixing member and the pressure member. A fixing device used in an image forming apparatus that fixes an unfixed image on the recording material to the recording material by heat and pressure by conveying the recording material sandwiched between the fixing member and the pressure member. A temperature control method comprising: a temperature detection step for detecting temperatures of the fixing member and the pressure member; a temperature storage step for storing a temperature detection result in the temperature detection step; and a target temperature of the fixing member and the target temperature setting step for a power amount determination step of determining the amount of power supplied to said heating member in accordance with the target temperature set in the target temperature setting step, Re of the image forming apparatus the transition from the dy standby state to the printing state, the conveying speed in response to the operating state changes, including at least one of the transition from the cooling state to the printing state, said the detected temperature of the pressure member or the fixing member recording material And a target setting correction table selection step for selecting one target setting correction table in response to the change in the operation state , and a detected temperature of the pressure member or the fixing member. And a transport speed changing step of changing the transport speed of the recording material from the selected target setting correction table.

The fifth technical means is a program for causing a computer to execute the temperature control method which is the fourth technical means.

The sixth technical means is a computer-readable recording medium on which a program which is the fifth technical means is recorded.

  According to the present invention, when the fixing member is heated, the sheet conveyance speed is changed according to the temperature of the pressure member, so that the temperature ripple of the fixing member and the pressure member is effectively suppressed with a simple configuration. be able to. Therefore, it is possible to prevent problems such as deterioration in image quality and winding of the recording material due to overheating and insufficient heat. In addition, since overheating of the fixing member and the pressure member can be prevented, excessive energy consumption can be reduced and energy saving can be achieved.

1 is a cross-sectional view of an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view of a fixing device according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of a heating member provided in the fixing device according to the embodiment of the present invention. It is a top view of the heating member with which the fixing device concerning one embodiment of the present invention is equipped. 3 is a block diagram of a control unit provided in the fixing device according to the embodiment of the present disclosure. FIG. 6 is a flowchart showing a flow of processing in the fixing device according to the embodiment of the present invention. 6 is a table showing an example of an output setting table used in a fixing device according to an embodiment of the present invention. 6 is a graph showing a waveform of an energization voltage to a heating member in a fixing device according to an embodiment of the present invention. 6 is a table showing an example of a target setting correction table used in the fixing device according to the embodiment of the present invention. FIG. 6 is a cross-sectional view showing a modification of the fixing device of the present invention. FIG. 6 is a cross-sectional view showing a modification of the fixing device of the present invention. FIG. 6 is a cross-sectional view showing a modification of the fixing device of the present invention. FIG. 6 is a cross-sectional view showing a modification of the fixing device of the present invention. It is a table | surface which shows the example of the target setting correction table used in the fixing device which concerns on other embodiment of this invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of a fixing device, an image forming apparatus, a temperature control method for the fixing device, a program, and a recording medium according to the invention will be described with reference to the drawings. In the following description, the same reference numerals in different drawings are the same, and the description thereof may be omitted.

(Embodiment 1)
An embodiment of the present invention will be described. In the present embodiment, the case where the present invention is applied to a color printer will be mainly described. However, the application target of the present invention is not limited to this, and the present invention can be applied to any electrophotographic image forming apparatus. For example, the present invention can be applied to a color multifunction machine, a color copying machine, a monochrome multifunction machine, a monochrome copying machine, a monochrome printer, and the like in addition to a color printer.

  FIG. 1 is a cross-sectional view of an image forming apparatus (color printer) 100 according to the present embodiment. As shown in this figure, an image forming apparatus 100 includes an exposure unit (optical system unit) E, four sets of visible image forming units pa to pd, an intermediate transfer belt unit 10, a secondary transfer unit 14, a fixing device 30, an internal A paper feed unit 16 and a manual paper feed unit 17 are provided. The operation of each member provided in the image forming apparatus 100 is controlled by a main control unit including a CPU (not shown).

  Image data handled in the image forming apparatus 100 corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y). For this reason, as shown in FIG. 1, four sets of visible image forming units pa to pd corresponding to the respective colors are provided, and four color toners formed by these four sets of visible image forming units pa to pd. Images are superimposed on an intermediate transfer belt 11 provided in the intermediate transfer belt unit 10.

  In the visible image forming unit pa, a charging unit 103a, a developing unit 102a, and a cleaning unit 104a are arranged in this order along the rotation direction of the photoconductor 101a around a photoconductor 101a that is rotatably provided as a toner image carrier. It is the structure arranged by.

  The charging unit 103a is for uniformly charging the surface of the photoreceptor 101a to a predetermined potential. In the present embodiment, the charging unit 103a employs a charging roller method (contact charging method) in order to uniformly charge the surface of the photoreceptor 101a without generating ozone as much as possible. However, the configuration of the charging unit 103a is not limited to this. For example, a non-contact charger such as a corona discharge method may be used, or a contact charger such as a brush charger may be used.

  The developing unit 102a performs a developing process for developing the electrostatic latent image formed on the photoreceptor 101a with a developer. As the developer, for example, a non-magnetic one-component developer (non-magnetic toner), a non-magnetic two-component developer (non-magnetic toner and carrier), a magnetic developer (magnetic toner) and the like can be used.

  The cleaning unit 104a is for removing and collecting the toner remaining on the surface of the photoreceptor 101a after the toner image is transferred to the intermediate transfer belt 111.

  The visible image forming units pb to pd have substantially the same configuration as the visible image forming unit pa except that the color of the toner used for the development processing is different. That is, black (B), yellow (Y), magenta (M), and cyan (C) toners are stored in the developing units of the visible image forming units pa, pb, pc, and pd, respectively.

  The exposure unit E exposes the photoconductors 101a to 101d charged by the charging units 103a to 103d according to image data, thereby forming electrostatic latent images according to the image data on the surfaces of the photoconductors 101a to 101d. To do. As the exposure unit E, a laser scanning unit (LSU) including a laser irradiation unit 4 and a reflection mirror 8 is used. As the exposure unit E, for example, an EL or LED writing head in which light emitting elements are arranged in an array may be used.

  The intermediate transfer belt unit 10 includes an intermediate transfer belt 11, an intermediate transfer belt driving roller (tension roller) 11a, an intermediate transfer belt driven roller (tension roller) 11b, an intermediate transfer belt cleaning unit 12, and intermediate transfer rollers 13a to 13d. ing.

  The intermediate transfer belt 11 is an endless belt made of a film having a thickness of about 100 μm to 150 μm, and is stretched around the intermediate transfer rollers 13 a to 13 d, the intermediate transfer belt driving roller 11 a, and the intermediate transfer belt driven roller 11 b. 1 is rotated in the direction of arrow B shown in FIG. In addition, the toner images of the respective colors formed on the photoconductors 101a to 101d are transferred so as to sequentially overlap the intermediate transfer belt 11, and a color toner image (multicolor toner image) is formed on the intermediate transfer belt 11. It is like that. The intermediate transfer rollers 13a to 13d are arranged on the photosensitive members 101a to 101d via the intermediate transfer belt 11 at positions between the facing portions of the developing members 102a to 102d and the cleaning units 104a to 104d. It arrange | positions so that 101a-101d may be opposed. The toner images on the photoconductors 101a to 101d are transferred onto the intermediate transfer belt 11 by applying a high voltage (+) opposite to the toner charging polarity (−) to the intermediate transfer rollers 13a to 13d. It has become so. In addition, the toner image formed on the intermediate transfer belt 11 is transported to a facing portion between the intermediate transfer belt driving roller 11a and the secondary transfer unit 14, and onto a recording material (recording paper) transported to the facing portion. It is designed to be transcribed. The intermediate transfer belt cleaning unit 12 contacts the intermediate transfer belt 11 and removes and collects toner remaining on the intermediate transfer belt 11 after the toner image is transferred onto the recording material.

  The fixing device 30 has a fixing roller (belt suspension member) 31, a heating member (belt suspension member) 32, a fixing belt (fixing member) 33 suspended on the fixing roller 31 and the heating member 32, and the fixing roller 31. A pressure roller (pressure member) 34 is provided to be pressed with a predetermined load via the fixing belt 33. Then, the recording material on which the toner image is transferred by the secondary transfer unit 14 is applied to a pressure contact portion (fixing nip portion N) between the pressure roller 34 and the fixing belt 33 heated by the heating member 32. The toner image is fixed on the recording material by heat and pressure by feeding paper at intervals and passing through the press contact portion. The fixing speed is a recording material conveyance speed (so-called process speed), and in this embodiment, the fixing speed is set to 225 mm / sec. Further, the conveyance interval between the recording materials is set so that the copying speed (number of copies per minute) is normally 51 sheets / minute when A4 size paper is fed horizontally.

  Note that the surface of the recording material on which the unfixed toner image (unfixed image) is formed is in contact with the fixing belt 33, and the surface of the recording material opposite to the surface on which the unfixed toner image is formed is the pressure roller 34. Abut. Details of the fixing device 30 will be described later.

  The internal paper feeding unit 16 is for accumulating recording materials used for image formation. The manual paper feed unit 17 is provided on the side wall of the image forming apparatus 100 so as to be foldable, and is used for manually feeding a recording material. The paper discharge tray 18 is a tray on which the recording material on which an image has been formed is placed.

  In addition, the image forming apparatus 100 stores the recording material fed from the internal paper feeding unit 16 by the pickup roller 16a and the recording material fed from the manual paper feeding unit 17 by the pickup roller 17a. A paper conveyance path for sending the paper to the paper discharge tray 18 via the fixing device 30 is provided. A large number of roller members r for conveying the recording material are arranged in the paper conveyance path. A pickup roller 18a is provided immediately after the fixing device, and rotates reversely during double-sided printing, so that it cooperates with the paper feed roller 19 provided immediately before the secondary transfer unit 14 to thereby back the recording material. The recording material is conveyed so that is directed to the intermediate transfer belt 11 side.

  Next, the configuration of the fixing device 30 will be described. FIG. 2 is a cross-sectional view of the fixing device 30. As shown in this drawing, the fixing device 30 includes a fixing roller 31, a heating member 32, a fixing belt 33 suspended on the fixing roller 31 and the heating member 32, and the fixing roller 31 via the fixing belt 33. And a pressure roller (pressure member) 34 that is in pressure contact with a predetermined load (216 N in the present embodiment). In this embodiment, the nip width of the fixing nip portion N (the width in the recording material conveyance direction at the portion where the fixing belt 33 and the pressure roller 34 abut) is 7 mm.

  Further, a thermistor (temperature detection unit, central temperature detection unit) 35 a and a thermistor (temperature detection unit, end temperature detection unit) 35 b for detecting the temperature of the fixing belt 33 are provided at a position facing the fixing belt 33. A thermistor (temperature detection unit, pressure member temperature detection unit) 35 c for detecting the temperature of the pressure roller 34 is provided at a position facing the pressure roller 34. The thermistor 35a is provided at a position facing the approximate center in the width direction of the fixing belt 33 (specifically, a position shifted by 25 mm from the center in the width direction) in the region where the fixing belt 33 is wound around the heating member 32. The thermistor 35b is located at a position facing the vicinity of the end portion in the width direction of the fixing belt 33 (specifically, a position shifted by 150 mm from the center in the width direction) in the region where the fixing belt 33 is wound around the heating member 32. Is provided. Further, the thermistor 35c is disposed so as to face the pressure roller 34 at a position displaced from the center of the pressure roller 34 in the axial direction by 150 mm along the axial direction. A heater lamp (halogen lamp, pressure member heating unit) 36 for heating the pressure roller 34 is provided inside the pressure roller 34. In addition, the temperature detection results of the thermistors 35a, 35b, and 35c are transmitted to a temperature control unit 42 (see FIG. 5 described later). The energization of the heating member 32 and the heater lamp 36 is controlled so that the surface temperature of the roller 34 approaches a predetermined temperature. In the present embodiment, a non-contact type thermistor is used as the thermistor 35a, and contact type thermistors are used as the thermistors 35b and 35c.

  The fixing roller 31 presses against the pressure roller 34 via the fixing belt 33 to form a fixing nip portion N. Further, the fixing roller 31 is rotationally driven in the direction of the arrow shown in FIG. 2 by a rotational driving means including a motor, a gear, an actuator, an energizing element, etc. (not shown). When the fixing roller 31 is driven to rotate, the fixing belt 33 suspended from the fixing roller 31 is driven to rotate by the fixing roller 31, and the pressure roller 34 that is in pressure contact with the fixing belt 33 contacts the fixing belt 33. It is designed to be driven and rotated. In this embodiment, the fixing roller 31 is rotationally driven and the fixing belt 33 and the pressure roller 34 are driven to rotate. However, the present invention is not limited to this, and for example, the pressure roller 34 may be rotationally driven. Alternatively, both the fixing roller 31 and the pressure roller 34 may be driven to rotate. Further, a driving roller that contacts the fixing belt 33 may be provided, and the driving roller may be rotationally driven.

  In this embodiment, the fixing roller 31 has a two-layer structure in which an elastic layer 31b is formed around a cylindrical cored bar 31a. The material of the cored bar 31a is not particularly limited. For example, a metal such as iron, stainless steel, aluminum, copper, titanium, magnesium, or an alloy thereof can be used. The material of the elastic layer 31b is not particularly limited as long as it is a material having appropriate heat resistance and elasticity. For example, a rubber material such as silicon rubber or fluororubber can be used. Further, the cored bar 31a is not limited to a solid columnar shape but may be a hollow cylindrical shape. In the present embodiment, as the fixing roller 31, an elastic layer 31b made of silicon sponge rubber having a thickness of 5 mm is formed around a cored bar 31a made of cylindrical stainless steel having a diameter of 18 mm, and has a diameter of 28 mm and a length of 320 mm. A cylindrical roller member was used.

  In the present embodiment, the pressure roller 34 has a three-layer structure in which a cylindrical cored bar 34a, an elastic layer 34b, and a release layer 34c are formed in order from the inside. The material of the cored bar 34a is not particularly limited as long as it has an appropriate strength and thermal conductivity. For example, metals such as iron, stainless steel, aluminum, copper, titanium, and magnesium, or those metals An alloy or the like can be used. The material of the elastic layer 34b is not particularly limited as long as it is a material having appropriate heat resistance and elasticity. For example, a rubber material such as silicon rubber or fluorine rubber can be used. The release layer 34c may be made of any material having excellent heat resistance and release properties. For example, PFA (a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) or PTFE (polytetrafluoroethylene). ) And other fluororesins are suitable. In this embodiment, as the pressure roller 34, an elastic layer 34b made of silicon solid rubber having a thickness of 3 mm is formed around a core metal 34a made of an iron alloy (STKM) having an outer diameter of 24 mm and a wall thickness of 2 mm, Further, a cylindrical roller member having an outer diameter of 30 mm, on which a release layer 34c made of a PFA tube having a thickness of 30 μm was mounted, was used.

  Further, a heater lamp 36 for heating the pressure roller 34 from the inner surface is disposed inside the pressure roller 34. The heater lamp 36 is operated by the temperature control unit 42. Specifically, the heater lamp 36 is supplied by controlling the power supplied (energized) from the power supply circuit 43 to the heater lamp 36 in accordance with a control signal output from the temperature control unit 42. Light is emitted according to the electric power, and infrared rays are emitted from the heater lamp 36. The heat source driving means 45 handles high voltage and large current such as solid state relay (SSR), triac, thyristor, mechanical relay (simply referred to as relay), FET (field effect transistor), etc. It is composed of a drive element that can be used. Thereby, the inner peripheral surface of the pressure roller 34 is heated by absorbing infrared rays, and the entire pressure roller 34 is heated. In the present embodiment, the heater lamp 36 having a rated power of 300 W is used. In order to easily absorb the infrared rays emitted from the heater lamp 36, a heat resistant black paint having good absorption characteristics in the infrared wavelength region may be applied to the inner surface of the pressure roller 34.

The fixing belt 33 is heated to a predetermined temperature by the heat generated by the heating member 32 and heats the recording material P on which an unfixed toner image passing through the fixing nip portion N is formed. The heating member 32 is rotatably stretched. Thus, the fixing belt 33, the fixing roller 31 is adapted to rotated by the fixing roller 31 of Toko filtration rotationally driven.

  In this embodiment, as the fixing belt 33, an elastic layer (not shown) is formed on the surface of a hollow cylindrical base material (not shown), and a release layer (not shown) is formed on the surface. An endless belt member having a three-layer structure was used. The material of the base material is not particularly limited, and for example, a heat-resistant resin such as polyimide, polyamide, or aramid resin, or a metal material manufactured by rolling or electroforming such as stainless steel or nickel can be used. Further, the material of the elastic layer is not particularly limited as long as it is a material excellent in heat resistance and elasticity. For example, an elastomer material such as silicon rubber or fluorine rubber can be used. Further, the material of the release layer is not particularly limited as long as it is a material excellent in heat resistance and releasability. For example, fluorine resin such as PFA or PTFE can be used. The release layer may be a tube member made of a fluororesin such as PFA or PTFE and attached to the outer peripheral surface of the elastic layer, and the outer peripheral surface of the elastic layer is coated with a fluororesin such as PFA or PTFE ( It may be coated). Moreover, when using heat resistant resin, such as a polyimide, as a base material, in order to reduce the frictional resistance with the heating member 32, you may add a fluororesin to heat resistant resin.

  In this embodiment, an elastic layer made of silicon rubber having a thickness of 150 μm is formed on the outer peripheral surface of a substrate made of polyimide having a thickness of 70 μm, and further, a PFA tube having a thickness of 30 μm is formed on the outer peripheral surface of the elastic layer. An endless belt member having an inner diameter (a value obtained by dividing the inner circumferential length by the circumferential ratio π) 50 mm and a length of 315 mm provided with a release layer was used. As a result, in the cross section perpendicular to the axial direction of the fixing roller 31, the fixing belt 33 is connected to the straight line connecting the point where the fixing belt 33 starts to contact the fixing roller 31 by the rotation of the fixing belt 33 and the axis of the fixing roller 31. The contact angle θ of the fixing belt 33 with respect to the fixing roller 31, which is an angle formed by a point connecting the fixing roller 31 and a straight line connecting the axis of the fixing roller 31, is 185 °.

  The heating member 32 suspends the fixing belt 33 together with the fixing roller 31 and heats the fixing belt 33. FIG. 3 is a cross-sectional view of the heating member 32. As shown in FIGS. 2 and 3, in the present embodiment, as the heating member 32, a region in contact with the fixing belt 33 is a resistance heating layer (planar heating element) 32a, an insulating layer 32b, and a base material in order from the inside. A layered heating element having a four-layer structure in which a coating layer 32 d for reducing frictional resistance between the layer 32 c and the heating member 32 and the fixing belt 33 is formed is used.

  Specifically, in the present embodiment, as the base material layer 32c, a part of an aluminum alloy pipe having an outer diameter of 28 mm and a thickness of 1 mm cut along the axial direction is used. A coating layer 32d made of PTFE (tetrafluoroethylene resin) having a thickness of 20 μm is formed on the outer peripheral surface of the base material layer 32c, and an insulating layer 32b made of polyimide having a thickness of 30 μm is formed on the inner peripheral surface of the base material layer 32c. Formed. A resistance heating layer 32a is provided on the inner peripheral surface of the insulating layer 32b. As a result, the heating nip width, which is the contact width between the fixing belt 33 and the heating member 32 (the width in the rotation direction of the fixing belt 33), is 44 mm.

  A support portion made of an aluminum alloy pipe having a diameter of 20 mm is attached to a region of the heating member 32 that is not in contact with the fixing belt 33 at both axial ends, and this support portion is fixed to the side frame of the fixing device 30. ing. Thereby, even if the fixing belt 33 rotates, the heating member 32 does not rotate, and the fixing belt 33 slides on the surface of the heating member 32.

  FIG. 4 is a plan view of the heating member 32 as viewed from the inner peripheral surface side. Although the heating member 32 is curved in an arc shape as shown in FIG. 2, for convenience of explanation, the heating member 32 is drawn in a flat plate shape in FIG.

  As shown in FIG. 4, the resistance heating layer 32a has a plurality of electric resistance wires extending along the circumferential direction (arc direction) of the heating member 32 and being folded back at the end in the circumferential direction. It is a planar heating element in which lines are arranged in a planar shape. Moreover, one end of each electric resistance wire is connected to the power supply part 32e, and the other end is connected to the power supply part 32f. The electric resistance between the power supply units 32e and 32f is 10Ω, and the temperature control unit 42 controls the operation of the heat source driving means 45 so that power is supplied from the power supply circuit 43 and 100V is supplied to the power supply units 32e and 32f. The AC voltage is applied to generate about 1000 W of thermal energy.

  In this embodiment, the line width of each electric resistance line is 2.4 mm, the distance between adjacent electric resistance lines (including the folded portions of the same electric resistance line) is 2.4 mm, and each electric resistance line The length of the portion of the wire extending in the circumferential direction of the heating member 32 (length from the position folded at one end in the circumferential direction of the heating member 32 to the position folded at the other end) is 320 mm, electric resistance wire And the number of turns of each electric resistance wire was two. For convenience of explanation, FIG. 4 shows an example in which the number of electrical resistance lines is two.

  The heat generated in the resistance heating layer 32a in the heating member 32 is transferred to the fixing belt 33 through the insulating layer 32b, the base material layer 32c, and the coat layer 32d. In the present embodiment, an aluminum alloy having high thermal conductivity is used as the base material layer 32c. For this reason, since the heat generated in each electric resistance wire of the resistance heating layer 32a can be dispersed over the entire peripheral surface of the heating member 32 by the base material layer 32c, fixing is caused due to the pattern shape of each electric resistance wire. The occurrence of uneven heating of the belt 33 can be mitigated. Further, even when a small-size recording material having a small contact width in the axial direction with respect to the fixing belt 33 compared to the contact width in the axial direction between the fixing belt 33 and the heating member 32 is used, the heating member The temperature distribution in the axial direction of 32 can be made uniform, and an excessive temperature rise can be prevented in the non-sheet passing portion.

  Next, processing during fixing processing in the fixing device 30 will be described. FIG. 5 is a block diagram illustrating a schematic configuration of the control unit 40 that controls the operation of each unit of the fixing device 30.

  As shown in FIG. 5, the control unit 40 includes a rotation drive control unit 41, a temperature control unit 42, and a paper transport control unit 46. The control unit 40 may be provided in the main control unit of the image forming apparatus 100, and is provided separately from the main control unit, and controls the operation of the fixing device 30 in cooperation with the main control unit. May be. The control unit 40 includes a RAM (not shown) that temporarily stores various types of data. Each unit included in the control unit 40 temporarily stores data handled by each unit in the RAM as necessary. Or read from the RAM as necessary.

  The rotation drive control unit 41 controls the operation of the rotation drive unit 44 for driving the fixing roller 31, and detects a control command from the main control unit of the image forming apparatus 100 and temperature detection of the thermistors 35 a, 35 b, and 35 c. The rotation driving means 44 of the fixing roller 31 is controlled so that the fixing roller 31 is rotationally driven or stopped at a predetermined timing according to the result or the like. The main control unit inputs an instruction from a user, a recording material placement state, a conveyance state, a size detection result, an operation state of each part of the image forming apparatus 100, an image forming mode (for example, a color mode) in the image forming apparatus 100. Or a monochrome mode), or a signal for controlling the rotation of the fixing roller 31 to the rotation drive control unit 41 in accordance with detection results of various sensors provided in the image forming apparatus 100. Examples of the various sensors include, for example, a sensor that optically or mechanically detects the passing position of the recording material, a sensor that detects a mechanical state such as a motor or a movable part, and a mounting state of a cover or a cleaning member. Examples include a sensor and a sensor that detects the pressure state of the pressure roller 34.

  The temperature controller 42 controls the energization amount to the resistance heating layer 32 a provided in the heating member 32 and the heater lamp 36 provided in the pressure roller 34 according to the temperature detection result of the thermistors 35 a, 35 b, 35 c and the like. For this reason, the surface temperature of the fixing belt 33 and the pressure roller 34 is controlled by outputting a control signal to the heat source driving means 45.

  As shown in FIG. 5, the temperature control unit 42 includes a sensor data input unit 51, a temperature storage unit 52, a temperature deviation calculation unit 53, a table storage unit 54, an output determination unit 55, a power control unit 56, and a target temperature setting unit. 57.

  The sensor data input unit 51 detects a temperature change as a resistance value change based on the output signals of the thermistors 35a to 35c, converts the resistance value change into a voltage value change, and further handles the voltage value change by a computer. Convert to a digital signal. Then, a signal indicating the temperature detection result is output to the temperature storage unit 52 and the temperature deviation calculation unit 53. The thermistors 35a to 35c have a negative temperature coefficient in which, for example, the resistance value decreases as the temperature increases, and the resistance value increases as the temperature decreases.

  The temperature storage unit 52 stores the temperature detection results for the past predetermined time by the thermistors 35a to 35c. The predetermined time is set to an integral multiple of the temperature control cycle of the heating member 32 and the heater lamp 36 (the control cycle of the energization amount to the heating member 32 and the heater lamp 36), for example. Specifically, in the present embodiment, the predetermined time is set from one second before to the present, or from two seconds before to the present.

The temperature deviation calculation unit 53 includes a first temperature deviation that is a deviation between a first detected temperature that is a current detected temperature by the thermistor 35a and a preset target temperature (control target temperature) of the fixing belt 33, and a first temperature deviation. A second temperature deviation which is a deviation between the detected temperature and the second detected temperature which is a detected temperature before a predetermined time (for example, 1 second or 2 seconds before) by the thermistor 35 a is calculated and output to the output determination unit 55. The temperature deviation calculation unit 53 reads the second detected temperature from the temperature storage unit 52. The first detected temperature may be read from the temperature storage unit 52 by the temperature deviation calculation unit 53 or may be input from the sensor data input unit 51 to the temperature deviation calculation unit 53. The first temperature deviation and the second temperature deviation are obtained by the following equations.
1st temperature deviation = 1st detection temperature-target temperature 2nd temperature deviation = 1st detection temperature-2nd detection temperature

  Similarly, the temperature deviation calculation unit 53 also detects the temperature detection result by the thermistor 35c, the third detection temperature that is the current detection temperature by the thermistor 35c, and the preset target temperature of the pressure roller 34 (control target temperature). ) And a fourth temperature which is a deviation between the third detected temperature and a fourth detected temperature which is a detected temperature before the predetermined time (for example, 1 second or 2 seconds before) by the thermistor 35c. The temperature deviation is calculated and output to the output determination unit 55.

  The table storage unit 54 includes a first output setting table (an output direct setting table, a central table) in which a combination of the first temperature deviation and the second temperature deviation is associated with an amount of power to be supplied to the heating member 32. A second output setting table (pressurizing member table) in which a combination of the third temperature deviation and the fourth temperature deviation is associated with the amount of power to be supplied to the heater lamp 36 is stored.

  The output determination unit 55 reads the energization amount corresponding to the first temperature deviation and the second temperature deviation input from the temperature deviation calculation unit 53 from the first output setting table stored in the table storage unit 54 and reads the heating member 32. The energization amount is determined and transmitted to the power control unit 56. In addition, the output determination unit 55 reads the energization amount corresponding to the third temperature deviation and the fourth temperature deviation input from the temperature deviation calculation unit 53 from the second output setting table stored in the table storage unit 54 and heaters The energization amount to the lamp 36 is determined and transmitted to the power control unit 56.

  The first output setting is made according to the difference between the temperature detection result of the thermistor 35b (temperature in the vicinity of the end portion in the width direction of the fixing belt 33) and the temperature detection result of the thermistor 35a (temperature in the center portion of the fixing belt 33 in the width direction). The energization amount read from the table may be corrected. For example, in accordance with the above difference, the widthwise end of the fixing belt 33 (the non-sheet passing area that does not contact the recording material) to the widthwise center of the fixing belt 33 (the sheet passing area that contacts the recording material). What is necessary is just to correct | amend so that the temperature of a paper passing area | region may approach target temperature in consideration of the amount of heat transfer. Alternatively, the temperature deviation calculation unit 53 calculates the deviation between the temperature detected by the thermistor 35b before a predetermined time (for example, 1 second or 2 seconds before) and the current temperature detected by the thermistor 35b, and the output determination unit 55 calculates the deviation. Accordingly, the energization amount read from the first output setting table may be corrected.

  The power control unit 56 outputs a control signal for controlling the energization amount from the power supply circuit 43 to the heating member 32 based on the energization amount transmitted from the output determination unit 55 to the heat source driving unit 45.

  The target temperature setting unit 57 has a function of setting a target temperature (control target temperature) of the fixing belt 33 and a target temperature (control target temperature) of the pressure roller 34, and the sensor data input unit 51 or the temperature storage unit 52 A necessary target temperature is set using the obtained temperature data of the thermistors 35a, 35b, and 35c, a target temperature set value stored in the storage unit of the control unit 40, and a target setting correction table described later.

  Further, the control unit 40 takes out the recording material from the paper storage unit (also referred to as a paper cassette), conveys the recording material to the image forming unit, and forms a toner image on the recording material at regular intervals. A sheet conveyance control unit 46 that performs control for conveyance is provided. The paper conveyance control unit 46 determines the printing speed of the recording material so that the recording material is conveyed at a time interval determined for each predetermined paper size and continuous printing is performed. For example, control is normally performed to print 51 sheets per minute for A4 size horizontal feed, or to print 31 sheets per minute for A4 size vertical feed. As described above, the paper conveyance control unit 46 determines the conveyance speed (fixing speed or process speed) of the recording material. Then, the paper conveyance control unit 46 changes the conveyance speed so that the nip passage speed becomes slow when the heating is insufficient, and changes the conveyance speed so that the nip passage speed becomes high when the heating is excessive. ing.

  Next, the processing flow of the fixing device will be described based on the flowchart shown in FIG. In the present embodiment, the second detection temperature is the detection temperature 1.5 seconds ago.

  First, the sensor data input unit 51 receives the detection signals of the thermistors 35a and 35b, detects (calculates) the first detection temperature and the third detection temperature based on these detection signals, respectively (step S1), and detects the detected first The detected temperature and the third detected temperature are stored in the temperature storage unit 52 (step S2).

  Next, the target temperature setting unit 57 reads out the third detected temperature, which is the detected temperature of the pressure roller 34, from the temperature storage unit 52 (step S3), and based on the read third detected temperature value, A target temperature is set (step S4). The third detected temperature may be input from the sensor data input unit 51 to the target temperature setting unit 57. A specific method for setting the target temperature will be described later.

  Next, the temperature deviation calculation unit 53 reads the first detection temperature and the second detection temperature from the temperature storage unit 52 (step S5), and based on each of these detection temperatures and the target temperature set in step S4, The second temperature deviation is calculated (step S6) and output to the output determination unit 55.

  Next, the output determination unit 55 reads the energization amount corresponding to the combination of the first temperature deviation and the second temperature deviation calculated by the temperature deviation calculation unit 53 from the first output setting table stored in the table storage unit 54. (Step S7), and output to the power control unit 56.

  FIG. 7 is a table showing an example of the first output setting table. In the example shown in this table, as the first output setting table 60, the energization amount (power amount) to the heating member 32 is set in advance, and the heating according to the combination of the first temperature deviation and the second temperature deviation is set. A value indicating the ratio of the energization amount to the maximum value (rated power) of the energization amount that can be supplied to the member 32 is stored. Then, the output determining unit 55 determines the energization amount read from the first output setting table as the energization amount to the heating member 32. For example, when the first temperature deviation ΔT1 is −1 ° C. and the second temperature deviation ΔT2 is −5 ° C., the power supplied to the heating member 32 is set to 100% of the rated power. When the first temperature deviation ΔT1 is −2 ° C. and the second temperature deviation ΔT2 is 0 ° C., the power supplied to the heating member 32 is set to 63% of the rated power.

  Thereafter, the power control unit 56 controls the amount of power supplied from the power supply circuit 43 to the heating member 32 by controlling the operation of the heat source driving unit 45 based on the amount of power determined by the output determining unit 55 (step S8). ).

  FIG. 8A is an explanatory diagram showing a control method (control waveform) of the energization amount to the heating member 32 by the power control unit 56. As shown in this figure, the power control unit 56 sets the ratio (duty ratio) between the time when the energization to the heating member 32 is turned on and the time when it is turned off based on the energization amount determined by the output determination unit 55. The power supply to the heating member 32 is controlled by the duty control method. For example, when the energization amount is set to the maximum energization amount, the energization is turned ON for the entire interval time (control cycle). When the energization amount is set to 63% of the maximum energization amount, the energization is turned ON only for a time corresponding to 63% of the interval time, and the energization is turned OFF for the time corresponding to the remaining 37%. In the present embodiment, a resistive heating element (resistance heating layer 32 a) is used as the heating member 32. Thereby, the resistive heating element has a smaller inrush current due to repeated energization ON and energization OFF than a halogen lamp frequently used as a heating means of the fixing device, and therefore flickering that causes flickering can be prevented.

  Note that the method for controlling the amount of power supplied to the heating member 32 is not limited to the duty control as described above. For example, as shown in FIG. 8B, a phase control method for controlling the phase of the AC power supply voltage supplied from the power supply circuit 43 to the heating member 32 via the heat source driving means 45 may be used. In this phase control method, the energization time is defined for each half wavelength of the AC voltage, and the power control is performed by controlling the phase angle of the conduction time according to the energization time for each half wavelength of the AC voltage. In the phase control method, power control can be performed while suppressing the inrush current of an inductive heating element such as a halogen lamp. In other words, if the energization heating element such as a halogen lamp is energized ON and energized finely, the current fluctuation due to the inductive load increases and induces a large voltage fluctuation of the AC power supply. Phase control is suitable for power control when a heating element is used.

  Further, the amount of power supplied to the heating member 32 may be controlled by combining the above-described duty control and phase control. In this case, for example, according to the energization amount determined by the output determination unit 55, whether to perform duty control or phase control may be appropriately selected based on a preset condition. Further, for example, an AC voltage may be converted into a DC voltage using an inverter and driven by pulses, and the amplitude of the AC voltage may be controlled according to the energization amount determined by the output determination unit 55. Further, the energization amount may be controlled by controlling the pulse width and the number of pulses of the DC voltage.

  On the other hand, the sheet conveyance control unit 46 determines in which temperature range (area) of the target setting correction table 61 shown in FIG. The number of prints per unit time, that is, the conveyance speed of the recording paper is read (step S9) and output to the rotation drive control unit 41.

  Then, the rotation drive control unit 41 drives and controls the rotation control means 44 in accordance with the conveyance speed received from the paper conveyance control unit 46 (step S10).

  Thereafter, the temperature control unit 42 determines whether or not to end the fixing process (step S11). If not, the process from S1 is repeated.

  In the example of FIG. 6, the temperature control process of the heating member 32 has been described. However, the temperature control unit 42 may perform the temperature control of the heater lamp 36 by a substantially similar method. That is, the sensor data input unit 51 receives the detection signal of the thermistor 35c, detects the third detection temperature, and stores the detected third detection temperature in the temperature storage unit 52. The temperature deviation calculation unit 53 reads the third detection temperature and the fourth detection temperature from the temperature storage unit 52, calculates the third temperature deviation and the fourth temperature deviation based on each detection temperature, and the output determination unit 55 The energization amount corresponding to the combination of the third temperature deviation and the fourth temperature deviation is read from the second output setting table stored in the table storage unit 54, and the power control unit 56 is based on the energization amount, and the heat source driving means 45. By controlling this operation, the amount of power supplied from the power supply circuit 43 to the heater lamp 36 is controlled. Even when the temperature of the heater lamp 36 is controlled, the target temperature of the pressure roller 34 may be set based on the value of the first detected temperature of the thermistor 35a.

  As described above, in the fixing device 30 according to the present embodiment, the first temperature deviation that is the deviation between the first detected temperature that is the current temperature detection result of the fixing belt 33 and the target temperature of the fixing belt 33, and the first The energization amount to the heating member 32 corresponding to a combination of one detected temperature and a second temperature deviation that is a deviation from a second detected temperature that is a temperature detection result of a predetermined time before the fixing belt 33 (for example, one second before). Set in advance. Then, the amount of power supplied to the heating member 32 is controlled based on the combination of the first temperature deviation and the second temperature deviation calculated based on the temperature detection result of the fixing belt 33 and the target temperature. Then, when setting the target temperature of the fixing belt 33, the temperature of the pressure roller 34 is taken into consideration.

  Thereby, the temperature ripple of the fixing belt 33 and the pressure roller 34 can be effectively suppressed with a simple configuration. Therefore, it is possible to prevent problems such as deterioration in image quality and winding of the recording material due to overheating and insufficient heat. Further, since overheating of the fixing belt 33 and the pressure roller 34 can be prevented, excessive energy consumption can be reduced and energy saving can be achieved.

  In the present embodiment, the configuration in which the heating member 32 uniformly heats the fixing belt 33 in the width direction has been described. However, the present invention is not limited to this. For example, a heating member (a central heating member) that heats the center portion in the width direction of the fixing belt 33 and a heating member (an end heating member) that heats an end portion in the width direction may be provided. In this case, for example, for the central heating member, temperature control is performed based on a combination of the temperature detection result of the thermistor (central temperature detection unit) 35a and the first temperature deviation and the second temperature deviation based on the target temperature, and the end heating member Is the fifth temperature deviation that is the deviation between the fifth detected temperature that is the current detected temperature of the thermistor (end temperature detector) 35b and the target temperature, the sixth detected temperature that is the detected temperature before a predetermined time, and the fifth The temperature may be controlled based on a combination with a sixth temperature deviation that is a deviation from the detected temperature. That is, a third output setting table (end portion table) indicating the amount of power to be supplied to the end heating unit corresponding to the combination of the fifth temperature deviation and the sixth temperature deviation is stored in the table storage unit 54. The amount of power to be supplied may be determined by reading it.

  Further, the configuration, size, control conditions, and the like of each member provided in the fixing device 30 are not limited to the examples shown in the present embodiment, and can be changed as appropriate. Also, the output setting table is not limited to the above-described example, and may be set as appropriate according to the fixing speed, copying speed, fixing method, configuration of each member, size, control conditions, and the like.

  Next, in this embodiment, for example, when the target temperature of the fixing belt 33 is set, correction is performed based on the value of the detected temperature of the pressure roller 34. This will be described.

  The state of the fixing device at the time of printing can take various temperature states such as a state immediately after starting up the image forming apparatus, a state in which the image forming apparatus has been started, and a state in which the image forming apparatus has been on standby for a while, or a state immediately after the completion of printing of a plurality of sheets. . In each state, the thermal energy required for heating and melting the toner image on the recording material hardly changes unless the recording material and the use environment temperature change greatly.

  However, in the various temperature states as described above, the temperatures of the fixing belt 33, the fixing roller 31, the pressure roller 34, and the like are different, and the ambient temperature state is also different. In such a case, when the fixing belt 33, the fixing roller 31 and the pressure roller 34 are heated by setting a uniform temperature, the toner image on the recording material is excessively heated as described above, or The necessary heat energy may not be supplied. That is, depending on the temperature state of the fixing belt 33, the fixing roller 31, and the pressure roller 34, there are optimum temperature states for fixing the toner image. Image degradation such as high temperature offset and fixing failure occurs.

  Therefore, in order to fix the toner image under optimum conditions even in various temperature states, the present invention focuses on the temperature state of the pressure roller 34.

  Here, the optimum conditions can be called fixing performance maintaining conditions. For example, regarding the temperature condition, the temperature of the fixing member and the pressure roller may change to a state different from the original target temperature due to indirect heating with time change. Even in such a state, it is possible to start printing immediately and to indicate that the fixing performance is good. That is, the optimum temperature condition is not a specific one point, but indicates the temperature range of the fixing member and the pressure member that can maintain substantially the same fixing performance in the peripheral region.

  In various temperature states of the fixing device, the temperature of the fixing belt 33 and the fixing roller 31 is often relatively easy to control. When heating is required, the heating member 32 can be energized to increase the temperature with good response. If heating is not necessary, the temperature can be lowered immediately by de-energizing, so that the temperature can be lowered. However, although the fixing device has a low heat capacity as a whole, the pressure roller 34 has a relatively large heat capacity, and the temperature rise / fall is not responsive because it is accompanied by a time delay. This applies to members that are difficult to change to the optimal state.

  On the other hand, depending on the amount of heat stored in the pressure roller 34, even if there is a slight delay in the heat supply or the environmental temperature fluctuates, the temperature followability can be maintained.

  Therefore, the temperature state of the pressure roller 34 is monitored, and from that temperature state, the degree of change in the temperature state of the fixing belt 33 and the fixing roller 31, the adjustment of the number of printed sheets, the conveyance speed of the recording material, and the heat storage operation If the control such as the adjustment of the waiting time is flexibly applied, it is possible to perform printing by bringing the fixing device close to the optimum temperature state.

  For example, when the printing is started, the temperature of the pressure roller 34 immediately before is acquired by the thermistor 35c, and is reflected in the target temperature setting of the fixing belt 33 at the time of printing as the temperature state during the previous printing waiting operation. Thus, it is possible to solve the excessive temperature and the shortage of heat from the beginning to the middle of printing and supply the necessary thermal energy to the toner image on the recording material.

  That is, the target temperature when controlling the heat generation of the heating member 32 is lowered or raised depending on whether the temperature of the pressure roller immediately before starting printing is higher or lower than a certain temperature threshold. Thus, when the temperature of the pressure roller 34 is high, the target temperature when controlling the heat generation of the heating member 32 is set low in order to lower the surface temperature of the fixing belt 33 to be close to the optimum temperature state. To do. That is, since the heat energy supplied from the pressure roller 34 to the recording material increases, the target temperature of the fixing belt 33 is reduced in order to reduce the heat energy supplied from the fixing belt 33 or the fixing roller 31 to the recording material. Set low.

  Conversely, when the temperature of the pressure roller 34 is low, the supply of thermal energy from the pressure roller 34 to the recording material decreases, and accordingly, the thermal energy supplied from the fixing belt 33 or the fixing roller 31 is increased. Therefore, the target temperature of the fixing belt 33 is set high.

  Since such control depends on the temperature of the pressure roller 34, the state immediately after startup of the image forming apparatus, the state of waiting for a while after startup, or the state immediately after the completion of printing of a plurality of sheets. It can be applied regardless of various temperature states, and can be realized based on the target setting correction table 61 as shown in FIG. For example, when the temperature of the pressure roller 34 is less than 110 ° C., for example, regardless of whether printing is started or immediately before the recording material is conveyed to the fixing device, the target temperature of the fixing belt 33 is set to + 10 ° C. The target temperature correction is performed, and the supply heat energy from the heating member 32 is increased so as to prevent the heat supply from becoming insufficient.

  Here, the actual target temperature value is a value obtained by adding the correction value obtained from the target setting correction table 61 to the target temperature setting value stored in the storage unit of the control unit 40 in advance. The target setting correction table 61 may be stored in advance in the storage unit of the control unit 40 or may be stored in the table storage unit 54.

  In the target setting correction table 61a shown in FIG. 9, the target temperature of the fixing belt 33 is corrected even when the number of elapsed prints changes, and the absolute value for correcting the target temperature decreases as the number of elapsed prints increases. However, when the number of printed sheets is not considered, for example, when the temperature of the pressure roller is in each area, only the temperature correction value described in “Up to 10th sheet” may be used. Good.

  However, since the temperature of the fixing belt and the pressure member sequentially changes, in order to maintain the fixing performance according to each temperature condition at that time, it is necessary to lead to the fixing performance maintaining condition, and the number of prints passes. Since the temperature of these members also changes every time, it is desirable that the target temperature value of the fixing belt is also corrected based on the number of elapsed printings in order to obtain the fixing performance maintaining condition at that time. For example, even if the heating amount is simply increased or decreased, if the heating performance is good, the temperature reaches in a short time and the heater lamp is turned off, but undershooting may cause another harmful effect.

In the present embodiment, the target temperature correction value corresponding to the temperature state of the pressure roller is divided into, for example, three areas as shown in the target setting correction table 61 in FIG. 9 to correct the target temperature of the fixing member. At the same time, control is performed to change the number of printed sheets per unit time (recording paper conveyance speed). Here, it can be said that the target setting correction table 61 associates the recording material conveyance speed with the detected temperature of the pressure member.

  In this method, the temperature state of the pressure roller 34 is divided, and conditions for changing to the optimum temperature state are provided according to each temperature state, and the recording material conveyance speed (conveyance interval) is set. The amount of heat energy supplied to the recording material is optimized by changing the passage time of the recording material through the fixing nip.

For example, the temperature of the pressure roller 34, when it is determined that the area 1 of the target setting correction table 61 shown in FIG. 9, the target temperature setting of the fixing belt 33, performs as illustrated, + 10 ° C. and plus correction . On the other hand, when the area is determined to be area 1, if the change in the target temperature of the fixing belt 33 is too rapid or a large target temperature correction needs to be applied, the plus correction cannot be set to be unnecessarily large. For this reason, the conveyance speed per unit time, that is, the number of printed sheets per unit time is changed from 51 to 48 in conjunction with this. Accordingly, a long time is required for the recording material to pass through the fixing nip portion, and the thermal energy necessary for the recording material is supplied.

Conversely, when the area 3 is determined and the temperature of the pressure roller 34 is 141 ° C. or higher, the number of printed sheets per unit time is increased to promote heat transfer from the pressure roller 34 to the recording material. Then, the temperature of the pressure roller 34 is changed to a lower one so that printing is performed in an optimum state. In the target setting the correction table 61, although the three areas provided as a temperature range of the pressure roller 34, may be changed to transport speed and temperature correction value by more have fine range. Moreover, targeting correction table 6 1 may be stored in the table storage unit 54, but for the relationship between the transport speed and the area (segment), and previously stored in the sheet conveyance control unit 46 as a separate table Also good.

  In addition to this, when the target temperature is negatively corrected, the cooling fan provided around or inside the fixing device is controlled by the rotation driving means 44 in accordance with the correction of the target temperature, and the air Forcibly cooling may be performed so that the temperature of the fixing unit itself, the fixing belt 33, the fixing roller 31, and the pressure roller 34 is lowered by the flow to reduce the deviation from the optimum temperature. At that time, if the detected temperature of the pressure roller is high, the air flow of the cooling fan may be increased.

  As described above, in the present embodiment, the heater lamp 133 a provided at a position corresponding to the center portion in the width direction of the fixing belt 33 and the heater lamp 133 b provided at a position corresponding to the end portion in the width direction of the fixing belt 33. And a heater lamp 36 provided inside the pressure roller 34. Then, a first temperature deviation which is a deviation between the current detected temperature in the center in the width direction of the fixing belt 33 and the target temperature of the fixing belt 33, and the current detected temperature in the center in the width direction of the fixing belt 33 and a predetermined time ago. The energization amount to the heater lamp 133a is controlled based on the combination with the second temperature deviation which is a deviation from the detected temperature at the center in the width direction of the fixing belt 33. Based on the detected temperature of the pressure roller 34, the target temperature of the fixing belt 33 and the sheet conveying speed of the recording material are changed.

  Further, a third temperature deviation, which is a deviation between the current detected temperature of the pressure roller 34 and the target temperature of the pressure roller 34, the current detected temperature of the pressure roller 34, and detection of the pressure roller 34 a predetermined time ago. The energization amount to the heater lamp 36 may be controlled based on a combination with the fourth temperature deviation which is a deviation from the temperature. Further, a fifth temperature deviation, which is a deviation between the current detected temperature at the end in the width direction of the fixing belt 33 and the target temperature of the fixing belt 33, and a predetermined time before the current detected temperature at the end in the width direction of the fixing belt 33. The energization amount to the heater lamp 133b may be controlled based on a combination with a sixth temperature deviation which is a deviation from the detected temperature at the end in the width direction of the fixing belt 33.

  As described above, by setting the target temperature setting of the fixing belt 33 to be low depending on the temperature state of the pressure roller 34, the heat energy from a plurality of supply destinations to the recording material is set to an optimum supply state as a whole. Thus, it is possible to perform printing while preventing image deterioration such as winding, high temperature offset, and fixing failure. Then, by changing the nip passage speed of the recording material in accordance with the setting of the target temperature, the supply of thermal energy to the recording material is performed in a more optimal state.

  As described above, the temperature state of the pressure roller 34 may be further increased, and the correction value may be finely determined according to the increase in the category. In addition, the correction value can be changed over time, changed according to the elapsed time during printing standby, changed every time the number of printed sheets passes, changed according to changes in environmental temperature, basis weight of recording material and power supply It is also possible to change it according to printing conditions such as voltage status and connection status of peripheral devices. In that case, prepare multiple target setting correction tables, and target according to changes in time and status The setting correction table may be switched.

  FIG. 10 is a cross-sectional view of the fixing device 30b according to the present embodiment. The fixing device 30b is provided in the image forming apparatus 100 in place of the fixing device 30 shown in FIG.

  As shown in FIG. 10, the fixing device 30b is provided with a heating roller (heating member) 132 instead of the heating member 32 in the fixing device 30 shown in FIG. The heater lamp (center heating member) 133a and the heater lamp (end heating member) 133b are provided.

  The heating roller 132 is a hollow cylindrical roller member made of aluminum having an outer diameter of 28 mm and a wall thickness of 0.5 mm made of aluminum, and both ends thereof can be rotated by a heat insulating resin heat insulating bush and a support member made of a ball bearing. Is held in. Each of these support members is fixed to a frame biased by a biasing member such as a spring in a direction away from the fixing roller 31. As a result, a predetermined tension is applied to the fixing belt 33 stretched around the fixing roller 31 and the heating roller 132. Accordingly, when the fixing roller 31 is rotationally driven and the fixing belt 33 is driven and rotated by the fixing roller 31, the heating roller 132 is driven and rotated by the fixing belt 33.

  Inside the heating roller 132, heater lamps 133a and 133b are arranged. The heater lamp 133a is provided in a region having a predetermined width in the central portion of the heating roller 132 in the axial direction, and the heater lamp 133b is provided in a region having a predetermined width in both axial ends of the heating roller 132. The thermistor 35a is disposed at a position facing the heater lamp 133a via the fixing belt 33 and the heating roller 132, and the thermistor 35b is disposed at a position facing the heater lamp 133b via the fixing belt 33 and the heating roller 132. Has been.

  The operation of the heater lamps 133a and 133b is performed by the temperature control unit 42 controlling the operation of the heat source driving means 45. Specifically, the heat source driving unit 45 controls the power supplied (energized) from the power supply circuit 43 to the heater lamps 133a and 133b in accordance with a control signal from the temperature control unit 42, whereby the heater lamps 133a and 133b are supplied. Light is emitted in accordance with the electric power generated, and infrared rays are emitted from the heater lamps 133a and 133b. Thereby, the inner peripheral surface of the heating roller 132 is heated by absorbing infrared rays, and the entire heating roller 132 is heated. In order to easily absorb the infrared rays emitted from the heater lamps 133a and 133b, a heat-resistant black paint having good absorption characteristics in the infrared wavelength region may be applied to the inner surface of the heating roller 132.

  In each of the above embodiments, the case where a fixing device including only one set of a fixing roller, a fixing belt, and a pressure roller has been described. However, the present invention is not limited to this.

  For example, as shown in FIG. 11, a fixing device 30c including the fixing device 30 shown in FIG. 2 and a second fixing device 60 provided downstream of the fixing device 30 in the recording material conveyance direction is provided. It may be used.

  The fixing device 30c has a configuration in which a fixing roller 61 having a heater lamp 65 therein and a pressure roller 62 having a heater lamp 66 inside are brought into contact with each other with a predetermined load. It is rotationally driven in the reverse direction. Then, by passing the recording material between the rotationally driven fixing roller 61 and the pressure roller 62, the toner image primarily fixed on the recording material by the fixing device 30 is firmly fixed to the recording material. Let

  A thermistor 63 is disposed at a portion facing the fixing roller 61, and a thermistor 64 is disposed at a portion facing the pressure roller 62. Temperature control is performed based on the temperature detection results of both rollers by each thermistor. The unit 42 controls the energization amount to the heater lamps 65 and 66. As the temperature control method, for example, a method similar to the temperature control method of the heating member 32 and the heater lamp 36 can be used.

  The configurations of the fixing roller 61 and the pressure roller 62 are not particularly limited, and those conventionally used in a heat roller fixing type fixing device may be used. In the present embodiment, the fixing roller 61 and the pressure roller 62 have a three-layer structure in which a core metal, an elastic layer, and a release layer are formed in order from the inside. For the core metal, for example, a metal such as iron, stainless steel, aluminum, copper, or an alloy thereof is used. In addition, a heat-resistant rubber material such as silicon rubber or fluororubber is suitable for the elastic layer, and a fluororesin such as PFA or PTFE is suitable for the release layer.

  In addition, a guide member 70 such as a conveyance guide plate or a conveyance roller is provided between the fixing device 30 and the fixing device 60, and the recording material P that has been primarily fixed by the fixing device 30 is along the guide member. The second fixing process is performed by the fixing device 60 and the sheet is discharged.

  Further, when the recording material is thin or when it is desired to perform the fixing process quickly, the conveying direction of the recording material subjected to the primary fixing process by the fixing device 30 is switched by the guide member 70 and discharged without passing through the fixing device 60. The sheet may be conveyed to a detour path and discharged to the outside of the fixing device 30c by a plurality of conveyance rollers 71a and 71b disposed in the detour path.

  The heating means for heating the fixing roller 61 and the pressure roller 62 is not limited to the heater lamp, and an induction heating type heating means using induction heating may be used. You may use it combining a heating means suitably.

  Further, instead of the fixing device 60, a fixing device 30d including the fixing device 30 may be used. That is, as shown in FIG. 12, it is good also as a structure provided with 2 sets of fixing devices 30. FIG.

  In the configuration using these two-stage fixing type fixing devices, the heat capacity of each fixing device can be reduced, so that the heat responsiveness can be improved and the fixing process can be performed quickly. Moreover, the temperature ripple can be reduced by applying the temperature control method according to the present embodiment.

  In each of the above embodiments, the pressure roller 34 is used as the pressure member. However, the present invention is not limited to this. For example, as shown in FIG. 13, a twin belt fixing method using a pressure belt as the pressure member. The fixing device may be used.

  The fixing device 30e shown in FIG. 13 includes a fixing belt 33 rotatably suspended on a fixing roller 31, a heating member 32, and a fixing pad 38a, a pressure roller 34, a suspension roller (tension roller) 34B, and a pressure pad. And a pressurizing belt 33b that is rotatably supported by 38b. The thermistors 35a and 35b detect the surface temperature of the fixing belt 33 and transmit it to the temperature controller 42, and the thermistor 35c detects the surface temperature of the pressure belt 33b and transmits it to the temperature controller 42. Yes. The temperature control unit 42 controls the energization amount to the heating member 32 and the heater lamp 36 by the method described above.

  Also, the fixing pad 38a and the pressure pad 38b are located on the upstream side in the recording material conveyance direction with respect to the position where the fixing roller 31 and the pressure roller 34 are in pressure contact with each other via the fixing belt 33 and the pressure belt 33b. And it arrange | positions so that it may press-contact with a predetermined load via the pressurization belt 33b. As a result, a fixing nip portion is formed in a wide range from the facing portion between the pads 38a and 38b to the facing portion between the fixing roller 31 and the pressure roller 34, so that the conveyed recording material P can be efficiently heated. It has become.

  The pressure contact force between the fixing pad 38 a and the pressure pad 38 b is set smaller than the pressure contact force between the fixing roller 31 and the pressure roller 34. Therefore, in this configuration, the pressure distribution in the recording material conveyance direction is maximized at the facing portion between the fixing roller 31 and the pressure roller 34 which is the most downstream portion of the fixing nip portion. Thereby, it is possible to prevent the fixing belt 33 and the pressure belt 33b from slipping during rotation.

  As the fixing roller 31, the heating member 32, the fixing belt 33, and the pressure roller 34, the same fixing device as that shown in FIG. 2 can be used. Further, as the pressure belt 33b, the same belt as the fixing belt 33 can be used.

  As a material constituting the fixing pad 38a and the pressure pad 38b, for example, PPS (polyphenylene sulfide resin) can be used.

  The configuration of the suspension roller 34B is not particularly limited, but it is preferable to use a suspension roller having a low thermal conductivity from the pressure belt 33b. In this embodiment, a roller member in which a silicone sponge layer is provided around an iron alloy cored bar having an outer diameter of 30 mm and an inner diameter of 26 mm is used.

  When the fixing nip portion is formed by the fixing pad 38a and the pressure pad 38b which are not rotating bodies, the inner peripheral surfaces of the fixing belt 33 and the pressure belt 33b are rubbed against the pads, and the belts 33 and 33b When the friction coefficient between the inner peripheral surface and each of the pads 38a and 38b is large, the sliding resistance increases. As a result, problems such as image misalignment, gear breakage, and drive motor power consumption increase occur, and this problem is particularly noticeable in the twin belt system. Therefore, a low friction sheet layer is provided on the contact surfaces of the fixing pad 38a and the pressure pad 38b with the belts 33 and 33b. As a result, wear of the pads 38a and 38b due to rubbing with the belts 33 and 33b is prevented and sliding resistance can be reduced, so that good belt running performance and belt durability can be obtained.

  Even in such a twin belt type fixing device, the temperature ripple can be reduced by applying the control method of the present invention. In the first embodiment, the case where the target temperature of the fixing belt is changed and the conveyance speed is changed based on the detected temperature of the pressure roller has been described. However, the pressure can be applied without changing the target temperature of the fixing belt. Only the conveyance speed may be changed based on the detected temperature of the roller.

(Embodiment 2)
Another embodiment of the present invention will be described. FIG. 14 is a table showing an example of a target setting correction table used in a fixing device according to another embodiment of the present invention.

The target setting the correction table 62 shown in FIG. 14, based on the difference between the target temperature and the actual temperature (detected temperature) of the fixing member (Fixing belt or fixing roller), so as to change the number of printed sheets per unit time Yes. Here, the correction value of the target temperature of the fixing member is changed according to the temperature of the pressure member and the number of printed sheets. The target temperature of the fixing member is the target temperature before correction, and is set in advance, for example, as described above. This corresponds to the target temperature (control target temperature) of the fixing belt 33. In other words, the difference between the target temperature of the fixing member and the actual temperature corresponds to the first temperature deviation before the target temperature is corrected.

  When the actual temperature (detected temperature) of the fixing member is low, for example, less than −24 ° C. lower than the target temperature, the conveyance speed is slowed to set the number of printed sheets per unit time to 41 sheets / min. As the actual temperature (detected temperature) increases, the number of printed sheets per unit time is increased. Thus, by changing the passage time of the recording material through the fixing nip portion, the amount of heat energy supplied to the recording material is set to an optimum state. When the control target temperature of the fixing member is set to a predetermined value, the range of the difference between the target temperature of the fixing member and the actual temperature in the target setting correction table 62 shown in FIG. 14 is the range of the actual temperature (detected temperature). Can be replaced. Therefore, it can be said that the target setting correction table 62 shown in FIG. 14 associates the recording material conveyance speed with the detected temperature of the fixing member.

  In each of the above embodiments, for example, when temperature control is started (for example, when the power is turned on or when returning from the sleep state), when temperature control conditions are changed (for example, when the target temperature setting is changed, the type of recording material is changed) When changing, when changing the printing speed (process speed), when changing the operating state of the image forming apparatus (for example, when shifting from the Ready standby state to the printing state (fixing processing state), from the warm-up state to the Ready standby state ), Transition from printing to cooling (waiting at a lower temperature than during fixing processing and warming up), transition from cooling to standby, transition from cooling to printing, etc.) When predetermined conditions during printing operation (for example, the elapsed time from the start of printing, the number of printed sheets from the start of printing, the elapsed number of printed sheets during printing, the remaining number of printed sheets, etc.) expire Other operating conditions in the fixing devices 30 and 30b such as when the temperature control condition is changed, when the energization amount is changed, when a predetermined condition during the printing operation in the fixing devices 30 and 30b is completed, when the printing operation is completed, and when the energy saving state is in the preheating state A plurality of output setting tables 60 and target setting correction tables 61 and 62 may be set according to various printing conditions such as when changing. Then, the temperature control unit 42 and the paper conveyance control unit 46 may perform control so that the fixing condition of the recording material is optimized under each condition. These conditions described above may be divided into a plurality of groups, and the output setting table 60 and the target setting correction tables 61 and 62 may be set for each group.

  Although the embodiments have been described above, in each embodiment, the main control unit of the image forming apparatus 100 and the control unit 40 of the fixing devices 30 and 30b may be realized by software using a processor such as a CPU. . In this case, the image forming apparatus 100 and the fixing devices 30 and 30b expand a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, and the program. A random access memory (RAM), and a storage device (recording medium) such as a memory for storing the program and various data. An object of the present invention is to allow a computer to read program codes (execution format program, intermediate code program, source program) of control programs for the image forming apparatus 100 and the fixing apparatuses 30 and 30b, which are software that realize the functions described above. The recording medium recorded in (1) is supplied to the image forming apparatus 100 and the fixing devices 30 and 30b, and the computer (or CPU or MPU) reads and executes the program code recorded on the recording medium.

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  Further, the image forming apparatus 100 and the fixing devices 30 and 30b may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Further, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  In addition, the main control unit of the image forming apparatus 100 and the control unit 40 of the fixing devices 30 and 30b are not limited to those realized using software, and may be configured by hardware logic and processing. A combination of hardware that performs a part of the above and arithmetic means that executes software that controls the hardware and performs the remaining processing may be used.

  As described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope disclosed in the claims, and the technical means disclosed in different embodiments can be appropriately combined. Such embodiments are also included in the technical scope of the present invention.

Reference numerals 30, 30b to 30e: fixing device, 31: fixing roller (belt suspension member), 32: heating member (central heating member, end heating member), 33: fixing belt (fixing member), 33b: pressure belt (additional member) Pressure member), 34 ... pressure roller (pressure member), 35a ... thermistor (temperature detection unit, central temperature detection unit), 35b ... thermistor (temperature detection unit, end temperature detection unit), 35c ... thermistor (pressure application) Member temperature detection unit), 36 ... heater lamp (pressure member heating unit), 38a ... fixing pad (belt suspension member), 38b ... pressure pad (pressure member), 40 ... control unit, 41 ... rotation drive control unit 42 ... Temperature control unit 43 ... Power supply circuit 44 ... Rotation drive means 45 ... Heat source drive means 46 ... Paper transport control part 51 ... Sensor data input part 52 ... Temperature storage part 53 ... Temperature deviation calculation part , 54 ... Tab Storage unit, 55 ... output determination unit, 56 ... power control unit, 57 ... target temperature setting unit, 60 ... first output setting table 61, 62 ... target setting correction table 100 ... image forming apparatus, 132 ... heating roller (Heating member) 133a ... Heater lamp (central heating member), 133b ... Heater lamp (end heating member).

Claims (6)

A fixing member and a pressure member that are rotatably provided, a heating member that heats the fixing member to a target temperature, a temperature control unit that controls the amount of power supplied to the heating member, the fixing member, and the pressure A sheet conveyance control unit that controls a conveyance speed of a recording material inserted between the recording member and the recording material by conveying the recording material while being sandwiched between the fixing member and the pressure member. A fixing device used in an image forming apparatus for fixing an unfixed image to the recording material by heat and pressure,
The temperature controller is
A temperature detector for detecting temperatures of the fixing member and the pressure member;
A target temperature setting unit for setting a target temperature of the fixing member;
An output determining unit that determines an amount of electric power to be supplied to the heating member based on the target temperature set by the target temperature setting unit and the detected temperature of the fixing member;
The fixing device is configured to change the pressure member or the fixing according to an operation state change including at least one of a transition from the ready standby state to the printing state and a transition from the cooling state to the printing state of the image forming apparatus. Having a plurality of target setting correction tables associating the detected temperature of the member with the conveyance speed of the recording material,
The sheet conveyance control unit selects one target setting correction table according to the change in the operation state, and records the recording from the selected target setting correction table based on the detected temperature of the pressure member or the fixing member. A fixing device that determines a conveyance speed of a material and changes the conveyance speed of the recording material. The fixing device further includes a cooling fan,
The fixing device according to claim 1 , wherein the cooling fan is driven in accordance with a detected temperature of the pressure member. An image forming apparatus characterized in that it comprises a fixing device according to claim 1 or 2. A fixing member and a pressure member that are rotatably provided, and a heating member that heats the fixing member to a target temperature, and a recording material inserted between the fixing member and the pressure member is the fixing member. And fixing the unfixed image on the recording material to the recording material by heat and pressure by being conveyed while being sandwiched by the pressure member, and a temperature control method for a fixing device used in an image forming apparatus,
A temperature detecting step for detecting temperatures of the fixing member and the pressure member;
A temperature storage step for storing a temperature detection result in the temperature detection step;
A target temperature setting step for setting a target temperature of the fixing member;
A power amount determining step for determining a power amount to be supplied to the heating member based on the target temperature set in the target temperature setting step;
The detected temperature of the pressure member or the fixing member according to a change in the operation state including at least one of transition from the Ready standby state to the printing state and transition from the cooling state to the printing state of the image forming apparatus. A target setting correction table selection step for selecting one target setting correction table in accordance with the change of the operation state from among a plurality of target setting correction tables associated with recording material conveyance speeds;
A fixing device temperature control method comprising: a conveyance speed changing step of changing a conveyance speed of the recording material from the selected target setting correction table based on a detected temperature of the pressure member or the fixing member. A program for causing a computer to execute the temperature control method according to claim 4 . A computer-readable recording medium on which the program according to claim 5 is recorded.

Images