JP5194900B2 - Fixing apparatus, image forming apparatus, and program - Google Patents

Description

  The present invention relates to a fixing device, an image forming apparatus, and a program.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer or a copying machine, a toner image transferred onto a recording sheet is passed through a nip formed by a fixing roll and a pressure roll provided with a heat source, and the action of heat and pressure is applied. A fixing device that melts and fixes toner is used.

  As a technique relating to this type of fixing device, Patent Document 1 discloses a heating device that can easily detect a change in the conveyance speed due to thermal expansion of a pressure roller and convey a sheet at a predetermined speed in a film-type fixing apparatus. For the purpose of providing, a reflecting member is provided at one end portion of the fixing film that is externally mounted on the heater guide, and the speed of the fixing film is determined by detecting the detection interval of the reflecting member with a reflection type sensor to convey the sheet. A technique for predicting the speed and controlling the driving speed of the pressure roller so as to be a predetermined speed is disclosed.

Patent Document 2 discloses that the pressure roller surface is obtained by driving the pressure roller alone or the downstream side of the pressure roller with respect to the sheet passing direction by a separate motor and pulling the main motor with a constant paper feed speed difference. A main motor for controlling the drive system of the image forming apparatus and another motor for driving the pressure roller for the purpose of guaranteeing a difference in speed at which the toner is cleaned and maintaining the speed of the pressure roller so as not to cause image stretching. When the pressure roller is thermally expanded, the pressure roller drive motor speed is controlled by the sensor means for detecting the outer diameter change of the pressure roller, and the pressure roller drive motor speed is always controlled by the pressure roller. A technique for making the speed difference between the upstream side and the downstream side constant is disclosed.
JP 2002-31744 A JP 2002-365959 A

  An object of the present invention is to provide a fixing device, an image forming apparatus, and a program capable of suppressing response delay and occurrence of overshoot when feedback control is performed on the rotation speed of a fixing member.

In order to achieve the above object, the fixing device according to claim 1 is rotatably supported, a fixing member that fixes the developer on the recording medium in a heated and rotated state, and the fixing device is rotatable. A pressure member that is supported and presses the recording medium against the fixing member in a rotated state when the developer is fixed to the recording medium by the fixing member; and the fixing member and the pressure member Driving means for rotationally driving; and moving means for moving the pressure member from a position spaced from the fixing member to a position pressed against the fixing member when fixing the developer on the recording medium; Detection means for continuously detecting the rotation speed of the fixing member at a predetermined sampling period; storage means for storing the rotation speed detected by the detection means; and storage means stored in the storage means. Based on the average value of a predetermined number of units of rotational speed, the rotational speed of the fixing member, and the predetermined target rotational speed so more increases after the pressing member is pressed from the front to be pressed The execution means for executing feedback control for performing the feedback control and the execution interval of the feedback control by the execution means are more after the movement than before the movement means is moved to the position where the pressing member is pressed against the fixing member. Changing means for changing a predetermined parameter so as to be longer.

  The invention according to claim 2 is the invention according to claim 1, wherein the predetermined parameter is the sampling period, and the changing means changes the sampling period from before the movement. It is changed so that the latter is longer.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the predetermined parameter is the predetermined number, and the changing means moves the predetermined number to the movement. It changes so that the number after the said movement may increase more than before.

  Furthermore, the invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the pressing member is moved to a position where the pressing member is pressed against the fixing member. The rotation speed of the fixing member for which feedback control is executed by the execution means is within a predetermined allowable rotation speed range when the recording medium is sandwiched between the fixing member and the pressure member. It is said that it is time to fit in.

  On the other hand, in order to achieve the above object, an image forming apparatus according to a fifth aspect includes a fixing device according to any one of the first to fourth aspects, an exposure unit that emits exposure light, and the exposure. Developing means for exposing the latent image formed by the exposure light by the means with a developer to form a developer image, and transfer means for transferring the developer image made visible by the developing means onto a recording medium; Conveying means for conveying the recording medium onto which the developer image has been transferred by the transfer means to the fixing device.

Further, in order to achieve the above object, the program according to claim 6 is rotatably supported, a fixing member that fixes the developer on the recording medium in a heated and rotated state, and the rotatable program. A pressure member that presses the recording medium against the fixing member in a rotated state when the developer is fixed to the recording medium by the fixing member, and the fixing member and the pressure member. Driving means for rotationally driving the member; and moving means for moving the pressure member from a position spaced from the fixing member to a position pressed against the fixing member when fixing the developer on the recording medium. Detecting means for continuously detecting the rotation speed of the fixing member at a predetermined sampling period, and detected by the detecting means on a computer A storage step of storing the rolling speed in the storage means, based on the average value of a predetermined number of units of the rotational speed stored in the storage means, the rotational speed of the fixing member, before the pressure member is pressed against An execution step of performing feedback control for setting a predetermined target rotational speed so that the pressure after pressing is higher, and an execution interval of the feedback control by the execution step is the pressurizing member by the moving unit. And a changing step of changing a predetermined parameter so that the length after the movement becomes longer than the position before the movement to the position pressed against the fixing member.

  According to the first, fifth, and sixth aspects of the invention, it is possible to obtain an effect that it is possible to suppress response delay and overshoot when feedback control is performed on the rotation speed of the fixing member.

  In addition, according to the second aspect of the present invention, it is possible to more easily suppress the occurrence of the response delay and the overshoot as compared with the case where the present invention is not applied.

  In addition, according to the third aspect of the present invention, it is possible to obtain the effect that the occurrence of the response delay and overshoot can be more easily suppressed as compared with the case where the present invention is not applied.

  Furthermore, according to the invention described in claim 4, it is possible to more reliably suppress the occurrence of the response delay and overshoot as compared with the case where the present invention is not applied.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, the case where the present invention is applied to an image forming apparatus (hereinafter referred to as “printer”) that forms an image by electrophotography will be described.

[First Embodiment]
First, the overall configuration of the printer 10 according to the present embodiment will be described with reference to FIG.

  As shown in the figure, the printer 10 according to the present embodiment has a yellow (Y), magenta (M), cyan (C), black (black) inside a casing 12 constituting the outer wall of the printer 10. Optical scanning devices 14Y, 14M, 14C, and 14K that emit light beams corresponding to the toners K) are fixed. A control unit 70 that controls the operation of each unit of the printer 10 is provided at a position adjacent to the optical scanning device 14K. In addition, parts including any of the letters “Y”, “M”, “C”, and “K” at the end of the code including the optical scanning devices 14Y, 14M, 14C, and 14K are added. It represents that it corresponds to the color corresponding to the character.

  The optical scanning devices 14Y, 14M, 14C, and 14K scan the light beam emitted from the light source with a rotating polygon mirror (polygon mirror) (not shown), and reflect the light beam with a plurality of optical components such as a reflection mirror, thereby corresponding colors. The light beams 16Y, 16M, 16C, and 16K corresponding to the toners are emitted.

  The light beams 16Y, 16M, 16C, and 16K are guided to the corresponding photoreceptors 18Y, 18M, 18C, and 18K, respectively. Each of the photoconductors 18Y, 18M, 18C, and 18K is rotated in the arrow A direction by a driving unit having a motor and a gear (not shown).

  Chargers 20Y, 20M, 20C, and 20K that charge the surfaces of the photoreceptors 18Y, 18M, 18C, and 18K are provided on the upstream side in the rotation direction of the photoreceptors 18Y, 18M, 18C, and 18K.

  Further, on the downstream side in the rotation direction of the photoconductors 18Y, 18M, 18C, and 18K, developing units 22Y, 22M, and Y for developing the Y, M, C, and K toners on the photoconductors 18Y, 18M, 18C, and 18K, respectively. 22C and 22K are provided.

  An intermediate transfer belt 28 to which the developed toner images are primarily transferred is disposed downstream of the developing units 22Y, 22M, 22C, and 22K in the rotational direction of the photoreceptors 18Y, 18M, 18C, and 18K.

The intermediate transfer belt 28 is constituted by a film-like endless belt in which an appropriate amount of an antistatic agent such as carbon black is contained in a resin such as polyimide or polyamide. And the volume resistivity is formed so that it may become 10 < ⁶ > -10 < ¹⁴ > (omega | ohm) cm, The thickness is comprised by about 0.1 mm, for example.

  At the position where the photoconductors 18Y, 18M, 18C, 18K and the intermediate transfer belt 28 face each other, the toner images of the respective colors formed on the photoconductors 18Y, 18M, 18C, 18K are formed on the inner side of the intermediate transfer belt 28. Primary transfer rolls 24Y, 24M, 24C, and 24K to be transferred to 28 are disposed. The primary transfer rolls 24Y, 24M, 24C, and 24K constitute a primary transfer unit 25 that performs primary transfer from the photoreceptors 18Y, 18M, 18C, and 18K to the intermediate transfer belt 28.

The primary transfer rolls 24Y, 24M, 24C, and 24K have a shaft (not shown) and a sponge layer as an elastic layer fixed around the shaft. Here, the shaft is a cylindrical bar made of metal such as iron or SUS. The sponge layer is a sponge-like cylindrical roll formed of a blend rubber of NBR, SBR, and EPDM containing a conductive agent such as carbon black and having a volume resistivity of 10 ^7.5 to 10 ^8.5 Ωcm. is there.

  The primary transfer rolls 24Y, 24M, 24C, and 24K are pressed against the photoreceptors 18Y, 18M, 18C, and 18K with the intermediate transfer belt 28 interposed therebetween. The primary transfer rolls 24Y, 24M, 24C, and 24K are charged with a voltage (primary voltage) opposite in polarity to the charging polarity of the corresponding color toner (in this embodiment, the negative polarity; the same applies hereinafter) by voltage application means (not shown). Transfer bias) is applied. As a result, the toner images on the photoconductors 18Y, 18M, 18C, and 18K are sequentially electrostatically attracted to the intermediate transfer belt 28, and a superimposed toner image is formed on the intermediate transfer belt 28.

  Further, cleaners 26Y, 26M, 26C, and 26K for removing residual toner on the photoconductors 18Y, 18M, 18C, and 18K are provided on the downstream side in the rotation direction of the photoconductors 18Y, 18M, 18C, and 18K.

  On the other hand, inside the intermediate transfer belt 28, a driving roll 30 that is driven by a motor (not shown) having excellent constant speed to move the intermediate transfer belt 28, and each of the photoreceptors 18Y, 18M, 18C, and 18K. A support roll 32 that extends substantially linearly along the arrangement direction and supports the intermediate transfer belt 28 is provided. Accordingly, the intermediate transfer belt 28 is driven to circulate at a predetermined speed in the arrow B direction.

  A tension roll 34 is provided inside the intermediate transfer belt 28 to apply a constant tension to the intermediate transfer belt 28 and prevent the intermediate transfer belt 28 from meandering.

  Further, a secondary transfer unit 42 that transfers the toner image on the intermediate transfer belt 28 onto the recording paper P is provided on the downstream side in the moving direction of the intermediate transfer belt 28.

  The secondary transfer unit 42 includes a secondary transfer roll 38 disposed on the toner image holding surface side of the intermediate transfer belt 28 and a backup roll 36.

The secondary transfer roll 38 includes a shaft (not shown) and a sponge layer as an elastic layer fixed around the shaft. Here, the shaft is a cylindrical bar made of metal such as iron or SUS. The sponge layer is formed of a rubber blend of NBR, SBR, and EPDM blended with a conductive agent such as carbon black, and has a volume resistivity of 1 × 10 ^7.5 Ωcm to 1 × 10 ^8.5 Ωcm. It is a sponge-like cylindrical roll.

  The secondary transfer roll 38 is disposed in pressure contact with the backup roll 36 with the intermediate transfer belt 28 interposed therebetween. Here, the secondary transfer roll 38 is grounded and a secondary transfer bias is applied between the secondary transfer roll 38 and the backup roll 36, and the toner image is secondarily transferred onto the recording paper P conveyed to the secondary transfer unit 42. .

The backup roll 36 is composed of a tube of EPDM and NBR blend rubber with carbon dispersed on the surface, and the interior is composed of EPDM rubber. The surface resistivity is 1 × 10 ⁷ Ω / □ or more and 10 ¹⁰ Ω / □ or less, and the hardness is set to, for example, 70 ° (Asker C).

  The backup roll 36 is disposed on the back surface side of the intermediate transfer belt 28 to form a counter electrode of the secondary transfer roll 38, and the backup roll 36 is connected to the backup roll 36 through a metal power supply roll 40 disposed in contact with the backup roll 36. The next transfer bias is stably applied.

  An intermediate transfer belt cleaner 46 that removes residual toner and paper dust on the intermediate transfer belt 28 after the secondary transfer is provided downstream of the secondary transfer portion 42 in the moving direction of the intermediate transfer belt 28. It is provided so that it can contact and separate. A cleaning backup roll 44 is provided inside the intermediate transfer belt 28 in the intermediate transfer belt cleaner 46.

  On the other hand, on the upstream side of the primary transfer roll 24Y corresponding to yellow toner, a home position sensor 48 for generating a signal serving as a reference for adjusting the timing of image formation corresponding to each toner is provided.

  The home position sensor 48 detects a predetermined mark provided on the back side of the intermediate transfer belt 28 and generates a reference signal. Based on this reference signal, the aforementioned control unit 70 operates each unit of the printer 10 and starts image formation.

  Further, an image density sensor 43 for adjusting image quality is provided on the downstream side of the primary transfer roll 24K corresponding to black toner.

  On the other hand, a paper tray 50 for storing the recording paper P is provided below the printer 10. A pickup roll 52 is provided at one end of the paper tray 50 to take out and transport the recording paper P at a predetermined timing.

  Above the pick-up roll 52, a plurality of transport rolls 54 that are driven to rotate by a driving means (not shown) having a motor, gears, etc., and transport the recording paper P delivered by the pick-up roll 52 to the secondary transfer section 42 described above. , 56 are provided.

  A conveyance chute 58 for feeding the recording paper P to the secondary transfer unit 42 is provided on the downstream side of the conveyance roll 56 in the conveyance direction of the recording paper P.

  Further, a conveyance belt 60 that conveys the recording paper P, on which the secondary transfer of the toner image has been completed, to the fixing device 100 is provided in the sending direction of the recording paper P in the secondary transfer unit 42. The conveyor belt 60 is stretched by stretch rolls 57 and 59, and is provided so as to be movable by a driving unit having a motor and gears (not shown).

  A guide 62 for guiding the recording paper P to the fixing device 100 is provided on the inlet side of the fixing device 100. A paper stacking tray 64 fixed to the casing 12 of the printer 10 is provided on the exit side of the fixing device 100.

  Here, the image forming process of the printer 10 will be described.

  First, image data output from an image reading device (not shown), a personal computer, or the like is subjected to predetermined image processing by an image processing device (not shown). In the image processing apparatus, a predetermined image such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color editing, moving editing, etc. is applied to the input reflectance data. Processing is performed. The image data subjected to the image processing is converted into color material gradation data of four colors Y, M, C, and K, and is output to the optical scanning devices 14Y, 14M, 14C, and 14K.

  The optical scanning devices 14Y, 14M, 14C, and 14K irradiate the photoconductors 18Y, 18M, 18C, and 18K with the light beams 16Y, 16M, 16C, and 16K according to the input color material gradation data.

  The surfaces of the photoreceptors 18Y, 18M, 18C, and 18K are previously charged by the chargers 20Y, 20M, 20C, and 20K, and the surfaces are exposed by the light beams 16Y, 16M, 16C, and 16K, thereby forming an electrostatic latent image. Is done. The formed electrostatic latent images are developed as toner images of respective colors Y, M, C, and K by developing units 22Y, 22M, 22C, and 22K.

  Subsequently, the toner images formed on the photoconductors 18Y, 18M, 18C, and 18K are transferred onto the intermediate transfer belt 28 in the primary transfer unit 25. In this transfer, the primary transfer rolls 24Y, 24M, 24C, and 24K apply a voltage (primary transfer bias) having a polarity opposite to the toner charging polarity (minus polarity) to the intermediate transfer belt 28, and transfer the toner image to the intermediate transfer belt 28. This is done by sequentially superimposing on the surface.

  Subsequently, the intermediate transfer belt 28 onto which the toner image has been transferred is conveyed to the secondary transfer unit 42.

  On the other hand, the pickup roll 52 rotates in accordance with the timing at which the toner image is conveyed to the secondary transfer unit 42, and a recording paper P having a predetermined size is sent from the paper tray 50.

  The recording paper P sent out by the pickup roll 52 is transported by the transport rolls 54 and 56, and reaches the secondary transfer unit 42 through the transport chute 58. Before reaching the secondary transfer portion 42, the recording paper P is temporarily stopped, and a registration roll (not shown) rotates in accordance with the movement timing of the intermediate transfer belt 28 on which the toner image is held. The position of P and the position of the toner image are aligned.

  In the secondary transfer unit 42, the secondary transfer roll 38 is pressed against the backup roll 36 via the intermediate transfer belt 28. At this time, the recording paper P conveyed at the same timing is sandwiched between the intermediate transfer belt 28 and the secondary transfer roll 38.

  At this time, a voltage (secondary transfer bias) having the same polarity as the toner charging polarity (negative polarity) is applied from the power supply roll 40, and a transfer electric field is formed between the secondary transfer roll 38 and the backup roll 36. The The unfixed toner image held on the intermediate transfer belt 28 is pressed by the secondary transfer roll 38 and the backup roll 36 and is electrostatically transferred onto the recording paper P at once.

  Subsequently, the recording paper P on which the toner image has been electrostatically transferred is conveyed as it is while being peeled off from the intermediate transfer belt 28 by the secondary transfer roll 38, and is conveyed to the conveyance belt 60.

  The conveyance belt 60 conveys the recording paper P to the fixing device 100 in accordance with the optimum conveyance speed in the fixing device 100. The unfixed toner image on the recording paper P conveyed to the fixing device 100 is fixed on the recording paper P by the fixing device 100.

  The recording paper P on which the fixed image is formed is discharged to the paper stacking tray 64 and stacked.

  On the other hand, after the transfer onto the recording paper P is completed, the residual toner remaining on the intermediate transfer belt 28 is conveyed to the intermediate transfer belt cleaner 46 as the intermediate transfer belt 28 rotates, and from the intermediate transfer belt 28. Removed.

  In this way, image formation by the printer 10 is performed.

  Next, the fixing device 100 according to the present embodiment will be described.

  As shown in FIG. 2, the fixing device 100 includes a housing 122 in which an opening for entering or discharging the recording paper P is formed.

  Inside the housing 122, an endless fixing belt 102 that rotates in the direction of arrow D is provided.

  As shown in FIG. 4B, the fixing belt 102 has a base layer 134, a heat generating layer 132, a protective layer 130, an elastic layer 128, and a release layer 126 from the inside to the outside, and these are laminated. And are united.

  The base layer 134 serves as a base for maintaining the strength of the fixing belt 102 and is made of polyimide (PI). The thickness of the base layer 134 is 30 to 80 μm. As the base layer 134, nonmagnetic stainless steel may be used.

The heat generating layer 132 is a metal material that generates heat by an electromagnetic induction effect in which an eddy current flows so as to generate a magnetic field that cancels a magnetic field H (see FIG. 2) to be described later. For example, gold, silver, copper, aluminum, zinc, tin , Lead, bismuth, beryllium, antimony, or a metal material thereof can be used. In the present embodiment, copper is used as the heat generating layer 132 from the viewpoint of efficiently obtaining a necessary heat generation amount by reducing the specific resistance to 1.7 × 10 ⁻⁸ Ωm or less and reducing the cost.

  In addition, the heat generation layer 132 is preferably as thin as possible because it has a smaller heat capacity and can shorten the warm-up time of the fixing device 100.

The protective layer 130 is made of a synthetic resin equivalent to the base layer and has a thickness of 40 to 60 μm, or is made of nonmagnetic stainless steel (specific resistance 7.2 × 10 ⁻⁷ Ωm) and has a thickness of 30 to 30 μm. 60 μm. Further, it may be made of nickel (specific resistance 7 × 10 ⁻⁸ Ωm) and the thickness may be 5 to 9 μm.

  The elastic layer 128 is made of silicon rubber or fluorine rubber from the viewpoint of obtaining excellent elasticity and heat resistance, and in this embodiment, silicon rubber is used.

  The release layer 126 is provided in order to weaken the adhesive force with the toner T (see FIG. 2) melted on the recording paper P so that the recording paper P can be easily separated from the fixing belt 102. In order to obtain excellent surface release properties, it is preferable to use a fluororesin, a silicon resin, or a polyimide resin as the release layer 126. In this embodiment, PFA (tetrafluoroethylene / perfluoroalkoxyethylene copolymer) is used. Polymerization resin). In the present embodiment, the release layer 126 has a thickness of 30 μm.

  On the other hand, as shown in FIG. 2, a bobbin 108 made of an insulating material is disposed at a position facing the outer peripheral surface of the fixing belt 102. The distance between the bobbin 108 and the fixing belt 102 is about 1 to 3 mm. The bobbin 108 is formed in a substantially arc shape that follows the outer peripheral surface of the fixing belt 102, and has a protruding portion 108A.

  An excitation coil 110 is wound around the bobbin 108 a plurality of times in the axial direction (the depth direction in FIG. 2) around the convex portion 108A.

  A magnetic core 112 made of a ferrite-based magnetic material formed in a substantially arc shape following the arc shape of the bobbin 108 is disposed at a position facing the exciting coil 110 and supported by the bobbin 108.

  On the other hand, a fixing member 114 made of a nonmagnetic material such as aluminum or nonmagnetic stainless steel is disposed inside the fixing belt 102 in a non-contact manner with both ends fixed to the casing 122 of the fixing device 100. Yes.

  The fixing member 114 includes an arc portion 114A formed in an arc shape facing the fixing belt 102, and a column portion 114B formed in a column shape, and the arc portion 114A and the column portion 114B are integrally formed.

  A magnetic core 116 made of the same material as that of the magnetic core 112 described above is provided along the circular arc portion 114 </ b> A on the circular arc portion 114 </ b> A of the fixing member 114. The magnetic core 116 is not in contact with the fixing belt 102. A closed magnetic path is formed between the magnetic core 116 and the magnetic core 112 by the magnetic field H penetrating the fixing belt 102, and the magnetic field H is strengthened. The magnetic core may be a magnetic shunt alloy (temperature-sensitive magnetic member).

  A support member 118 that supports the fixing belt 102 from the inside is fixed to the end face of the column portion 114B of the fixing member 114.

  The support member 118 is composed of a member having elasticity such as urethane rubber or sponge, and one end surface is in contact with the inner peripheral surface of the fixing belt 102 to press the fixing belt outward.

  On the other hand, at a position facing the outer peripheral surface of the fixing belt 102, the fixing belt 102 pressurizes the fixing belt 102 toward the support member 118 and rotates in the direction of arrow E by a drive mechanism having a motor and a gear (not shown). Is arranged.

  The pressure roll 104 has a configuration in which a core metal 106 made of a metal such as stainless steel or aluminum is coated with sponge, silicon rubber, and PFA (tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin). .

  The pressure roll 104 can be moved in the directions of arrows A and B by the retract mechanism shown in FIG. 5. When the pressure roll 104 moves in the direction of arrow A, the pressure roller 104 comes into contact with the outer peripheral surface of the fixing belt 102 and pressurizes. When moved in the B direction, it is separated from the outer peripheral surface of the fixing belt 102.

  Here, the retract mechanism of the pressure roll 104 will be described.

  FIG. 5 shows a retract mechanism unit 150 that contacts or separates the pressure roll 104 from the fixing belt 102.

  The retract mechanism 150 is made of sheet metal, and includes an arm member 152 to which a bearing (not shown) that rotatably supports both ends of the pressure roll 104 is fixed.

  The arm member 152 is attached to a pair of side plates 154 erected on both ends of the pressure roll 104 inside the casing 122 by columnar support pins 156, and can swing in the direction of arrow R1. .

  Bolts 158 are provided on the side surface of the side plate 154 substantially parallel to the side surface of the side plate 154. The front end portion of the bolt 158 is fastened to a hole portion 157 of a plate-like fixing portion 160 protruding from the side plate 154, and the rear end portion is fixed by being bonded to an engaging portion (not shown).

  Further, a plate-like urging portion 162 in which a hole portion 159 having a size into which the bolt 158 can be inserted is formed on the opposite side of the arm member 152 from the support pin 156.

  Here, the bolt 158 is inserted into the hole 159 of the urging portion 162, the spring 164 having a predetermined elastic force is externally inserted into the bolt 158, and the tip of the bolt 158 is fastened to the hole 157. Thus, the spring 164 is provided between the fixing portion 160 and the urging portion 162.

  The arm member 152 is urged downward by the urging force of the spring 164. As a result, the pressure roll 104 is separated from the fixing belt 102.

  On the other hand, an eccentric cam 166 is provided in the vicinity of the arm member 152. The eccentric cam 166 swings in the arrow R2 direction about a substantially cylindrical support pin 168 as an axis.

  The eccentric cam 166 is provided with a gear portion 172 having a predetermined number of teeth. A drive gear 174 having a predetermined number of teeth meshes with the gear portion 172. The drive gear 174 swings the eccentric cam 166 by forward rotation (counterclockwise rotation) and reverse rotation (clockwise rotation) of a drive motor 176 driven by a power source (not shown).

  Here, when the drive motor 176 rotates forward and the drive gear 174 rotates in the forward rotation direction, the eccentric cam 166 swings upward. As a result, the eccentric cam 166 contacts the arm member 152 to swing the arm member 152 toward the fixing belt 102, and the pressure roll 104 comes into contact (pressure contact) with the fixing belt 102.

  Further, when the drive motor 176 is reversed and the drive gear 174 rotates in the reverse direction, the eccentric cam 166 swings downward. As a result, the eccentric cam 166 is separated from the contact portion 170 of the arm member 152, the arm member 152 is biased downward by the spring 164, and the pressure roll 104 is separated from the fixing belt 102.

  As shown in FIG. 2, when the pressure roll 104 presses the fixing belt 102 toward the support member 118, a concave portion 103 is formed in the fixing belt 102 at a contact portion (nip portion) between the fixing belt 102 and the pressure roll 104. Thus, a convex portion 105 is formed at a position adjacent to the concave portion 103.

  The shape of the nip portion is curved in a direction to be peeled from the fixing belt 102 when the recording paper P on which the toner T is loaded passes. Therefore, the recording paper P conveyed from the direction of the arrow IN is discharged in the direction of the arrow OUT following the shape of the nip portion with its own waist strength.

  Further, the support member 118 presses the fixing belt 102 toward the pressure roll 104 and bends along the inner peripheral surface of the fixing belt 102 to widen the nip width.

  A thermistor 120 for measuring the temperature of the back surface of the fixing belt 102 is provided in contact with the back surface of the fixing belt 102 in the region facing the exciting coil 110 and the passing region of the recording paper P. The contact position of the thermistor 120 is substantially the center in the axial direction of the fixing belt 102 (the depth direction of the paper surface in FIG. 2) so that the measured value does not change depending on the size of the recording paper P.

  The thermistor 120 measures the temperature of the back surface of the fixing belt 102 by changing the resistance value according to the amount of heat given from the back surface of the fixing belt 102.

  As shown in FIG. 4A, the thermistor 120 is connected to a control circuit 138 provided inside the aforementioned control unit 70 (see FIG. 1) via a wiring 136. Further, the control circuit 138 is connected to the energizing circuit 142 via the wiring 140, and the energizing circuit 142 is connected to the above-described exciting coil 110 via the wirings 144 and 146.

  Here, the control circuit 138 measures the temperature of the back surface of the fixing belt 102 based on the amount of electricity sent from the thermistor 120, and the fixing temperature when fixing the toner T onto the recording paper P by the fixing device 100. A fixing set temperature (170 ° C. in the present embodiment) stored in advance in a predetermined area of a ROM 74, which will be described later, is compared as a suitable temperature on the back surface of the belt 102. When the measured temperature is lower than the fixing set temperature, the energizing circuit 142 is driven to energize the exciting coil 110, and a magnetic field H (see FIG. 2) as a magnetic circuit is generated. On the other hand, when the measured temperature is higher than the fixing set temperature, the energization circuit 142 is stopped.

  The energization circuit 142 is driven or stopped based on an electric signal sent from the control circuit 138, and supplies or stops supplying an alternating current having a predetermined frequency to the exciting coil 110 via the wires 144 and 146.

  As described above, in the printer 10 according to the present embodiment, the control circuit 138 performs feedback control for making the temperature of the fixing belt 102 coincide with the above-described fixing set temperature.

  Next, the rotation mechanism of the fixing belt 102 and the pressure roll 104 will be described. Each shaft and each gear are provided on the side plate of the above-described casing 122 (see FIG. 2).

  As shown in FIG. 6, the fixing device 100 includes a drive motor 180 that is energized and driven by the control unit 70 described above.

  A shaft 182 is attached to the drive motor 180, and a drive gear 184 is attached to the shaft 182. The drive gear 184 meshes with a large-diameter portion 188B of the first gear 188 that is extrapolated to the shaft 186. Further, the small-diameter portion 188 </ b> A of the first gear 188 is meshed with the second gear 192 that is extrapolated to the shaft 190.

  The second gear 192 is engaged with a third gear 196 that is extrapolated to the shaft 194 at a position different from the first gear 188. The third gear 196 is meshed with the fourth gear 200 that is extrapolated to the shaft 198 at a position different from the second gear 192.

  The fourth gear 200 is meshed with a pressure roll drive gear 204 that is externally attached to the shaft 202 of the pressure roll 104 at a position different from the third gear 196.

  The pressure roll drive gear 204 is always meshed with the fourth gear 200 even if the retract mechanism 150 described above is operated.

  On the other hand, the shaft 182 is provided with a gear 206 with a clutch in addition to the drive gear 184. The clutch-equipped gear 206 is meshed with a fifth gear 210 that is externally attached to the shaft 208.

  The fifth gear 210 is meshed with a fixing belt driving gear 214 that is externally attached to the shaft 212 at a position different from the gear 206 with the clutch. The fixing belt driving gear 214 is formed with a substantially cylindrical cap portion (not shown), and this cap portion is fitted into one end portion of the fixing belt 102 and fixed by adhesion.

  Each gear is fitted to each shaft, and is fixed so as not to come off the shaft by an E-ring (not shown) or the like.

  Further, the gear 206 with the clutch rotates idly when the peripheral speed when rotating by the pressure roll 104 is larger than the peripheral speed when rotating by the driving force of the driving motor 180, and the fixing gear is driven from the driving gear 184. The driving force transmitted to the gear 214 is cut off.

  Next, the configuration of the control unit 70 of the printer 10 will be described.

  As shown in FIG. 3, the control unit 70 includes a central processing unit (CPU) 72 that performs various controls of the printer 10, a ROM (Read Only Memory) 74 in which various control programs, various parameters, and the like are stored in advance. A RAM (Random Access Memory) 76 serving as a storage means for temporarily storing various data such as temperature measurement data measured by the thermistor 120 or used as a work area when executing various programs; And a timer 78 operating with the clock of The control unit 70 includes the control circuit 138 (see FIG. 4A).

  The CPU 72 is connected to an input / output interface 80 through which various signals are input / output. Via the input / output interface 80, the photosensor 117, the switch 82, the user interface (UI) 84, the thermistor 120, the drive motor. 180 and a drive motor 176. Note that the switch 82 is a switch for turning on / off the printer 10 (see FIG. 1), and the user interface 84 directly instructs the user to execute image formation or the like. Input panel.

  Here, signals are input to the CPU 72 from the photosensor 117, the switch 82, the user interface 84, and the thermistor 120 via the input / output interface 80. On the other hand, a control signal from the CPU 72 is output to the drive motor 180 and the drive motor 176 via the input / output interface 80.

  Next, the peripheral speed detection of the fixing belt 102 will be described.

  As shown in FIGS. 2 and 7, the photosensor 117 is disposed opposite to the outer peripheral surface of the fixing belt 102 at a predetermined distance.

  As shown in FIG. 7B, the photosensor 117 includes a light emitting portion 123 that emits light and reflected light (reflected by the object to be detected) inside a housing 121 that constitutes the main body of the photosensor 117. RL) to receive and convert it into an electrical signal.

  A power supply line 127 and a signal line 129 are connected to the photosensor 117. Here, light is emitted from the emission unit 123 when power is supplied from a power source (not shown) via the power line 127.

  The other end of the signal line 129 is connected to the CPU 72 (see FIG. 3) via the aforementioned input / output interface 80 (see FIG. 3), and is generated based on the amount of light received by the light receiving unit 125. The electrical signal (pulse signal) thus transmitted is sent to the CPU 72 through the signal line 129.

  As shown in FIG. 7A, in the longitudinal direction, the fixing belt 102 includes a paper passing area (L2) through which the recording paper P (traveling in the direction of the arrow C) passes and a non-paper passing area through which the recording paper P does not pass. (L1, L3). Here, a rectangular mark material 119 made of aluminum foil or a material having a reflectance different from that of the belt surface is provided in the non-sheet passing region L3 of the fixing belt 102.

  As shown in FIG. 7B, the mark material 119 is embedded between the elastic layer 128 and the release layer 126 in advance in the process of manufacturing the fixing belt 102. In the printer 10 according to the present embodiment, the mark material 119 has a thickness of 6 to 20 μm.

  Note that the release layer 126 of the fixing belt 102 is configured to be able to transmit the light emitted from the emission portion 123 of the photosensor 117 described above, and the light incident on the release layer 126 is the surface of the mark material 119. And is reflected by the light receiving unit 125 as reflected light RL.

  Further, as shown in FIG. 7A, the mounting position of the photosensor 117 described above is a position facing the moving region (L4) in which the mark material 119 moves.

  Here, when the fixing belt 102 rotates in the arrow X direction, the mark material 119 also moves in the arrow X direction.

  When the mark material 119 comes to a position facing the photo sensor 117, light is reflected by the mark material 119, and thus a high (High) level signal is output from the photo sensor 117. On the other hand, when the mark material 119 is not located at the position facing the photosensor 117, the reflected light RL hardly enters the photosensor 117 because light is irregularly reflected on the surface of the fixing belt 102. Low) level signal is output.

  Thereby, a pulse signal having a high level signal and a low level signal is generated. The peripheral speed of the fixing belt 102 is obtained by dividing the width of the mark material 119 by the time of the rising period (high level) of the pulse signal.

  The circumferential speed of the fixing belt 102 is measured by detecting the rotation of an actuator (such as a windmill having a plurality of wings, not shown) attached to the fixing belt driving gear 214 with a photo sensor. This may be done by generating a pulse signal having a level signal and a low level signal. In this case, there is less possibility of deterioration compared to the case where the mark material 119 is embedded in the layer of the fixing belt 102, and the peripheral speed can be reliably measured with a longer life.

  Next, as the operation of the present embodiment, the operation of the fixing device 100 particularly related to the present invention will be described in detail with reference to FIG. FIG. 8 shows the processing of a program (hereinafter referred to as a “fixing processing program”) in which only the portion related to the control of the fixing device 100 is extracted from the programs executed by the CPU 72 to perform the above-described image forming process. It is a flowchart showing the flow, and the program is stored in a predetermined area of the ROM 74 in advance.

  In step 500 of FIG. 5, the rotation of the fixing belt 102 and the pressure roll 104 is started by starting the supply of power to the drive motor 180. At this point, the pressure roll 104 is separated from the fixing belt 102 by the retract mechanism 150 (see FIG. 5).

  In the next step 502, sampling of the peripheral speed of the fixing belt 102 at a predetermined first sampling period (20 ms in this embodiment) (in this case, acquisition of the pulse signal from the photosensor 117, the pulse signal) The calculation of the peripheral speed of the fixing belt 102 by dividing the width of the mark material 119 in the rising period (high level period) and the storage of the peripheral speed in the RAM 76 are started.

  In the next step 504, based on the sampling result of the peripheral speed of the fixing belt 102 started by the processing in step 502, the peripheral speed of the fixing belt 102 is changed to a state where the pressure roller 104 is not in pressure contact with the fixing belt 102. Feedback control (hereinafter referred to as “circumferential speed feedback control”) for setting a single belt target speed (169.8 mm / s in the present embodiment) that is predetermined as the target peripheral speed of the fixing belt 102 in FIG. To start.

  In the printer 10 according to the present embodiment, as the peripheral speed feedback control, the average value in units of a predetermined number (in the present embodiment, 10) of the peripheral speeds stored in the RAM 76 by the sampling is the belt single target. The drive motor 180 increases the rotational speed of the pressure roll 104 by a predetermined speed when the speed is lower than the speed, and decreases the rotational speed of the pressure roll 104 by the predetermined speed when the average value is higher than the belt single target speed. The control which controls is applied. In the printer 10 according to the present embodiment, the predetermined speed for raising and lowering the rotation speed of the pressure roll 104 in the circumferential speed feedback control is the difference between the circumferential speed of the fixing belt 102 and the belt single target speed at that time. However, the present invention is not limited to this. For example, the speed according to only the peripheral speed of the fixing belt 102 at that time (as an example, the speed is 1/10 of the difference). Needless to say, any speed can be applied as long as the peripheral speed of the fixing belt 102 can be brought close to the belt single target speed, such as a mode in which the speed is 1/100 of the peripheral speed).

  In the next step 506, the control circuit 138 is controlled to start the feedback control of the temperature of the fixing belt 102 described above. When this feedback control is started, an eddy current is induced in the conductive layer 132 of the fixing belt 102 by the magnetic field H, and the fixing belt 102 generates heat. At this time, since the fixing belt 102 and the pressure roll 104 are not in contact with each other, the heat amount of the fixing belt 102 is not conducted to the pressure roll 104, and the fixing belt 102 can be heated and heated in a short time.

  In the next step 508, the system waits until a condition (hereinafter referred to as “pressure contact condition”) predetermined as a condition for pressing the pressure roll 104 against the fixing belt 102 is satisfied. In the printer 10 according to the present embodiment, the condition that the temperature of the back surface of the fixing belt 102 measured by the thermistor 120 has reached the fixing set temperature is applied as the pressure contact condition. Not limited to, for example, an experiment using an actual machine in advance as a period from the start of feedback control of the temperature of the fixing belt 102 by the processing of step 506 until the temperature of the back surface of the fixing belt 102 reaches the fixing setting temperature, Any condition may be used as long as the temperature on the back surface of the fixing belt 102 has reached the above-mentioned fixing set temperature, such as a condition that a period obtained by computer simulation using an actual machine design specification has passed. Needless to say, it can be applied.

  In the next step 510, the drive of the drive motor 176 of the retract mechanism unit 150 is started to start the pressure contact of the pressure roll 104 to the fixing belt 102, and the process waits until the pressure contact is completed in the next step 512. To do.

  In the next step 514, the sampling cycle of the peripheral speed of the fixing belt 102 started by the processing in step 502 is changed to a second sampling cycle (100 ms in the present embodiment) that is longer than the first sampling cycle. . Therefore, as a result of applying the second sampling period as the sampling period of the peripheral speed of the fixing belt 102 after that, that is, after the time when the pressure roll 104 is pressed against the fixing belt 102, the execution period of the peripheral speed feedback control is The period becomes longer according to the difference between the first sampling period and the second sampling period.

  In the next step 516, the target speed of the peripheral speed feedback control is determined in advance as the target peripheral speed of the fixing belt 102 in a state where the fixing belt 102 and the pressure roll 104 are in pressure contact from the single belt target speed. The fixing target speed is changed to 175 mm / s in the present embodiment. Therefore, thereafter, the peripheral speed feedback control is performed with the fixing target speed as a target.

  Thereafter, the recording paper P holding the unfixed toner image is fed into the fixing nip portion between the fixing belt 102 and the pressure roll 104.

  In the fixing nip portion, the toner image is heated and pressurized and fixed on the recording paper P.

  Subsequently, the recording paper P is peeled from the fixing belt 102 due to a change in the curvature of the fixing belt 102 at the exit of the fixing nip portion, and is conveyed to the paper stacking tray 64.

  In the next step 518, the process waits until a condition (hereinafter referred to as “end condition”) set in advance as a condition for ending the fixing process program is satisfied. In the printer 10 according to the present embodiment, the condition that the image forming process that is continuously executed is completed is applied as the termination condition. However, the present invention is not limited to this. The condition that an instruction input for stopping the execution of the image forming process is made via the interface 84, the condition that the printer 10 has a problem that the image forming process cannot be continued, the switch 82 is turned off, and the like. It goes without saying that other conditions such as these conditions can be applied.

  In the next step 520, a predetermined fixing end process is executed, and then the fixing process program is ended. In the printer 10 according to the present embodiment, as the fixing end process, the rotation of the fixing belt 102 and the pressure roll 104 started by the process of step 500 is stopped, and the fixing belt 102 started by the process of step 502 is used. The peripheral speed feedback control started by the process of step 504, the feedback control of the temperature of the fixing belt 102 started by the process of step 506, and the fixing by the process of step 510. Control is performed to separate the pressure roll 104 pressed against the belt 102 from the fixing belt 102.

  When fixing is continuously performed by the fixing device 100, the fixing belt 102 has a low heat capacity, so that the outer diameter hardly changes, but the outer diameter of the pressure roll 104 is expanded by thermal expansion.

  In particular, in the non-sheet passing region where the recording paper P of the pressure roll 104 does not pass, the recording paper P accumulates without taking heat, so that the temperature is higher than the paper passing region and the outer diameter becomes larger.

  If the fixing belt 102 and the pressure roll 104 are rotated in this state, a slip occurs between the fixing belt 102 and the pressure roll 104, and the toner image passing between the two expands.

  Further, since the fixing belt 102 is in contact with the pressure roll 104, the peripheral speed is increased so as to match the pressure roll 104, and the peripheral speed is higher than the peripheral speed by the fixing belt driving gear 214, so that the fixing belt 102 is easily buckled. turn into.

  However, in the retract mechanism 150 according to the present embodiment, when the peripheral speed of the fixing belt 102 rotated by the pressure roll 104 is larger than the peripheral speed of the fixing belt 102 rotated by the driving force of the drive motor 180, the clutch Since the attached gear 206 idles, the driving force transmitted from the driving gear 184 to the fixing belt driving gear 214 is interrupted.

  As a result, the fixing belt 102 rotates with the pressure roll 104, and slippage due to a difference in the peripheral speed between the fixing belt 102 and the pressure roll 104 is less likely to occur, so that the expansion of the toner image during fixing can be suppressed. .

  Further, the generation of torsional shear force due to the peripheral speed of the fixing belt 102 rotated by the pressure roll 104 being larger than the peripheral speed of the fixing belt 102 rotated by the driving force of the drive motor 180 is suppressed. The fixing belt 102 is less likely to buckle, and the fixing device 100 can be used for a long time.

  Here, at the time of continuous fixing, simply rotating the fixing belt 102 around the pressure roll 104 increases the peripheral speed.

  However, in the printer 10 according to the present embodiment, as shown in FIG. 7, the peripheral speed of the fixing belt 102 is detected based on the pulse signal detected by the photosensor 117, and the predetermined reference speed is used. If the speed is too fast, the rotational speed of the drive motor 180 is decreased so that the reference speed is reached.

  As a result, even if the fixing belt 102 rotates with the pressure roll 104, fluctuations in the peripheral speed of the fixing belt 102 are suppressed.

  On the other hand, according to an experiment using the actual printer 10 by the present inventors, as shown by the broken line in FIG. 9 as an example, the sampling period of the peripheral speed of the fixing belt 102 is set to a relatively short period (in the example shown in FIG. 9). 20ms), the process speed (peripheral speed of the fixing belt 102) when the peripheral speed feedback control is performed is responsive (good), but overshoot occurs and vibrates like chattering thereafter. As a result, it has been found that it takes a relatively long time to fall within the allowable speed range during the fixing process (in the example shown in FIG. 9, the range from 174.7 mm / s to 175.4 mm / s).

  On the other hand, as shown by a two-dot chain line in FIG. 9 as an example, the process speed when the peripheral speed feedback control is performed with the sampling period set as a relatively long period (100 ms in the example shown in FIG. 9) is a response. It was found that although it took a relatively long time to fall within the allowable speed range, the fluctuation was small and stable after entering the allowable speed range.

  Therefore, in the printer 10 according to the present embodiment, the above-described sampling cycle is moved after the sampling cycle before the pressure roll 104 is moved to the position where the pressure roller 104 is pressed against the fixing belt 102 by the above-described fixing processing program. The sampling cycle is lengthened.

  As a result, as shown by a one-dot chain line in FIG. 9 as an example, the overshoot and vibration are reduced, and stability after entering the allowable speed range is improved.

  By the way, in the example shown by the one-dot chain line in FIG. In some cases, the peripheral speed of the fixing belt 102 cannot be within the allowable speed range.

  Therefore, in the printer 10 according to the present embodiment, the timing at which the pressure roll 104 is moved to a position where it is pressed against the fixing belt 102 is set so that the peripheral speed of the fixing belt 102 by the peripheral speed feedback control is the above required timing. The timing is adjusted so as to be within the allowable speed range.

  Accordingly, as shown by a thick solid line in FIG. 9 as an example, the peripheral speed of the fixing belt 102 is within the allowable speed range by the necessary timing.

[Second Embodiment]
In the second embodiment, the number of the peripheral speeds stored in the RAM 76 by the above sampling, which is applied when calculating the average value of the peripheral speeds of the fixing belt 102 when performing the peripheral speed feedback control, is increased. A description will be given of an example in which the number of rolls 104 is larger than that before the roll 104 is pressed against the fixing belt 102.

  The configuration of the printer 10 according to the second embodiment is the same as that of the printer 10 according to the first embodiment (see FIGS. 1 to 7), and thus the description thereof is omitted here. .

  Hereinafter, the operation of the fixing device 100 particularly related to the present invention will be described in detail with reference to FIG. 10 as the operation of the second embodiment. FIG. 10 is a flowchart showing the flow of processing of the fixing processing program according to the second embodiment, and is a step for performing the same processing as the fixing processing program according to the first embodiment in the program. Are given the same step numbers as in FIG.

  As shown in the figure, the fixing processing program according to the second embodiment is different from the fixing processing program according to the first embodiment in that the processing in step 515 is replaced with the processing in step 514. The only difference is that the processing is applied.

  That is, in the fixing processing program according to the second embodiment, in the fixing processing program according to the first embodiment, the sampling cycle of the peripheral speed of the fixing belt 102 started by the processing of step 502 in step 514 is set. Instead of performing the process of changing to the second sampling period, which is a period longer than the first sampling period, the average value of the peripheral speeds of the fixing belt 102 in the peripheral speed feedback control started by the process of step 504 in step 515. The number of peripheral velocities stored in the RAM 76 by the above sampling (hereinafter referred to as “averaged number”) applied when calculating the pressure is compared before the pressure roll 104 is pressed against the fixing belt 102. Many (50 in this embodiment).

  Accordingly, the execution cycle of the peripheral speed feedback control is increased by a period corresponding to the increment of the averaging number thereafter, and as shown in FIG. 9 by an alternate long and short dash line, as in the first embodiment. In addition, the overshoot and vibration are reduced, and the stability after entering the allowable speed range is improved.

  Here, also in the printer 10 according to the second embodiment, the timing at which the pressure roll 104 is moved to the position where it is pressed against the fixing belt 102 is the peripheral speed of the fixing belt 102 by the peripheral speed feedback control. The timing is adjusted so as to be within the allowable speed range at the required timing.

  As a result, as in the first embodiment, the peripheral speed of the fixing belt 102 falls within the allowable speed range by the necessary timing as shown by a thick solid line in FIG. 9 as an example.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the above-described embodiment without departing from the gist of the invention, and embodiments to which such modifications or improvements are added are also included in the technical scope of the present invention.

  The above embodiments do not limit the invention according to the claims (claims), and all the combinations of features described in the embodiments are essential for the solution means of the invention. Is not limited. The embodiments described above include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. Even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, as long as an effect is obtained, a configuration from which these some constituent requirements are deleted can be extracted as an invention.

  For example, in each of the above embodiments, the case where the fixing process is realized by a combination of a software configuration and a hardware configuration has been described. However, the present invention is not limited to this, and for example, the fixing process is performed only by the software configuration. Alternatively, it may be realized only by a hardware configuration.

  In each of the above embodiments, the case where the present invention is applied to an electrophotographic image forming apparatus has been described. However, the present invention is not limited to this, for example, image formation using a liquid developer. It can also be set as the form applied to an apparatus.

  In each of the above embodiments, the case where the temperature of the fixing belt 102 is detected by the thermistor 120 has been described. However, the present invention is not limited to this, and is detected by another temperature sensor such as a thermocouple. It can also be in the form.

  Further, the clutch-equipped gear 206 in each of the above embodiments can be configured as another gear such as a gear having a torque limiter.

  In the first embodiment, a sampling period of the peripheral speed of the fixing belt 102 is applied as a parameter to be changed before and after the pressure roll 104 is moved to a position where it is pressed against the fixing belt 102. In the embodiment, the case where the above averaged number is applied has been described. However, both of these two types of parameters may be applied.

  In addition, the configuration of the printer 10 described in the above embodiments (see FIGS. 1 to 7) is merely an example, and unnecessary portions can be deleted or new portions can be deleted without departing from the gist of the present invention. Needless to say, it can be added.

  Furthermore, the processing flow of the fixing processing program described in each of the above embodiments (see FIGS. 8 and 10) is also an example, and unnecessary steps may be deleted or newly added within the scope not departing from the gist of the present invention. It goes without saying that simple steps can be added and the processing order can be changed.

1 is a cross-sectional side view illustrating an overall configuration of a printer according to an embodiment. FIG. 2 is a cross-sectional side view illustrating a configuration of a fixing device according to an embodiment. FIG. 2 is a block diagram illustrating a main configuration of an electric system of the printer according to the embodiment. (A) is a connection diagram showing an electrical connection state of the control circuit and the energization circuit according to the embodiment, and (b) is a cross-sectional view of the fixing belt according to the embodiment. It is a side view which shows the structure of the retract mechanism part which concerns on embodiment. FIG. 6 is a perspective view showing a meshing state of each gear in the fixing device according to the embodiment. (A) is a front view which shows the arrangement | positioning state of the photosensor which concerns on embodiment, (b) is a side view which shows the light detection state of the photosensor which concerns on embodiment. 4 is a flowchart illustrating a processing flow of a fixing processing program according to the first embodiment. FIG. 10 is a diagram for explaining the fixing process according to the embodiment, and is a graph showing an example of an actual measurement result of a relationship between an elapsed time from the start of rotation of the fixing belt and a process speed (a peripheral speed of the fixing belt). 10 is a flowchart showing a flow of processing of a fixing processing program according to a second embodiment.

Explanation of symbols

10 Printer 14Y, 14M, 14C, 14K Optical scanning device (exposure means)
22Y, 22M, 22C, 22K Developer (Developing means)
42 Secondary transfer part (transfer means)
60 Conveying belt (conveying means)
72 CPU (execution means, change means)
76 RAM (storage means)
102 Fixing belt (fixing member)
104 Pressure roll (Pressure member)
117 Photosensor (detection means)
150 Retract mechanism (moving means)
180 Drive motor (drive means)
P Recording paper (recording medium)
T Toner (Developer)

Claims (6)

A fixing member which is rotatably supported and which fixes the developer to the recording medium in a heated and rotated state;
A pressure member that is rotatably supported and presses the recording medium against the fixing member in a rotated state when the developer is fixed to the recording medium by the fixing member;
Drive means for rotationally driving the fixing member and the pressure member;
Moving means for moving the pressure member from a position spaced from the fixing member to a position pressed against the fixing member when fixing the developer on the recording medium;
Detecting means for continuously detecting the rotation speed of the fixing member at a predetermined sampling period;
Storage means for storing the rotational speed detected by the detection means;
Based on the average value of the rotation speeds stored in the storage unit in a predetermined number unit, the rotation speed of the fixing member is previously set so as to be higher after the pressure member is pressed than before the pressure member is pressed. Execution means for executing feedback control for achieving a predetermined target rotational speed;
The predetermined parameter is changed so that the execution interval of the feedback control by the execution unit is longer after the movement than before the movement of the pressing member to the position where the pressing member is pressed against the fixing member. Change means,
A fixing device provided with The predetermined parameter is the sampling period;
The fixing device according to claim 1, wherein the changing unit changes the sampling cycle so that the time after the movement is longer than that before the movement. The predetermined parameter is the predetermined number;
The fixing device according to claim 1, wherein the changing unit changes the predetermined number so that the number after the movement is larger than that before the movement. The timing at which the pressing member is moved to a position where the pressing member is pressed against the fixing member by the moving means is the rotational speed of the fixing member for which feedback control has been executed by the executing means, and the recording medium and the fixing member. The fixing device according to any one of claims 1 to 3, wherein the fixing device has a timing that falls within a predetermined allowable rotational speed range when being held between the pressing member and the pressure member. A fixing device according to any one of claims 1 to 4,
Exposure means for emitting exposure light;
Developing means for forming a developer image by revealing the latent image formed by the exposure light by the exposure means with a developer;
Transfer means for transferring the developer image made visible by the developing means onto a recording medium;
Conveying means for conveying the recording medium onto which the developer image has been transferred by the transfer means to the fixing device;
An image forming apparatus. A fixing member that is rotatably supported and that fixes the developer to the recording medium in a heated and rotated state, and is rotatably supported and fixes the developer to the recording medium by the fixing member. A pressing member that presses the recording medium against the fixing member in a rotated state, a driving unit that rotationally drives the fixing member and the pressing member, and the developer is fixed to the recording medium. And a moving means for moving the pressure member from a position spaced from the fixing member to a position pressed against the fixing member, and continuously detecting the rotation speed of the fixing member at a predetermined sampling cycle. Corresponding to a fixing device comprising:
On the computer,
A storage step of storing in the storage means the rotational speed detected by the detection means;
Based on the average value of the rotation speeds stored in the storage unit in a predetermined number unit, the rotation speed of the fixing member is set in advance so as to be higher after the pressure member is pressed than before the pressure member is pressed. An execution step of executing feedback control for achieving a predetermined target rotational speed;
The predetermined parameter is changed so that the execution interval of the feedback control in the execution step is longer after the movement than before the movement of the pressure member to the position where the pressure member is pressed against the fixing member. Change steps,
A program that executes

Images