Image forming device

Abstract

To provide an image forming apparatus that prevents a reduction in image quality when an abnormality in which a web is not taken up occurs in a web mechanism using a variable resistor.SOLUTION: An image forming apparatus forms a fixing nip part with a heating rotating body and a pressure rotating body and fixes an unfixed toner image to a recording material at the fixing nip part. The image forming apparatus comprises: a web that recovers a toner attached to a surface of the heating rotating body; a take-up roller that takes up the web; a variable resistor that is connected such that a resistance value can be changed according to the outer diameter of the web taken up by the take-up roller; and a control unit that controls the amount of rotation of the take-up roller according to the resistance value of the variable resistor. When the amount of change of information is equal to or less than a certain amount after a predetermined time, the control unit detects the presence of abnormality, and provides the details related to the abnormality.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus that forms a toner image on a recording material. [Background technology]

[0002] The image forming apparatus has a fixing device that fixes the unfixed toner image on the recording material to the recording material.

[0003] The fixing device has a pair of rotors, including a heating rotor that applies heat to unfixed toner and is driven to rotate, and a pressure rotor that applies pressure to the heating rotor to form a fixing nip between the heating rotor and the pressure rotor, which is also driven to rotate. When a recording material with unfixed toner on it is conveyed to the fixing nip, the heat of the heating rotor and the pressure of the pressure rotor are applied to the recording material, and the unfixed toner is fixed to the recording material.

[0004] In a fixing device, excessive heat from the heating rotor may be transferred to unfixed toner, resulting in hot offset, in which the toner adheres to the surface of the heating rotor without being fixed to the recording material. The toner (hot offset toner) remaining on the surface of the heating rotor due to hot offset may adhere to subsequent paper, resulting in poor image quality.

[0005] Therefore, a configuration in which a web unit is installed to remove hot offset toner is used (Patent Document 1).The hot offset toner can be removed and cleaned from the heating rotor using a web made of nonwoven fabric or the like.

[0006] The web used to clean the surface of the heating rotor is wound up by the rotation of the winding roller. The larger the amount of web wound up, the larger the outer diameter of the wound web. Therefore, in order to wind up the web accurately, the rotational speed of the winding roller when winding up the web is changed depending on the outer diameter of the wound web. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2001-282029 Summary of the Invention [Problem to be solved by the invention]

[0008] A variable resistor is used in the web unit to wind the web with precision. In the web unit using the variable resistor, the winding roller is rotated by a motor to wind the web.

[0009] If an abnormality occurs in which the take-up roller does not rotate and the web is not wound up, the abnormality may go unnoticed and the fixing operation may be performed without the web being wound up, which may result in insufficient toner recovery, and offset toner may adhere to subsequent paper, resulting in a deterioration in image quality.

[0010] Therefore, an object of the image forming apparatus according to the present invention is to suppress the degradation of image quality that occurs when an abnormality occurs in which the web is not wound up in a web mechanism that uses a variable resistor. [Means for solving the problem]

[0011] In consideration of the above problems, an image forming apparatus according to the present invention includes a heating rotor that heats unfixed toner carried on a recording material, a pressure rotor that pressurizes the heating rotor, a fixing nip formed by the heating rotor and the pressure rotor, which sandwiches and transports the recording material carrying unfixed toner through the fixing nip to fix an unfixed toner image on the recording material, a web that collects toner that is not fixed to the recording material and adheres to the surface of the heating rotor, a take-up roller that takes up the web used to collect the toner that has adhered to the surface of the heating rotor, a contact member that comes into contact with the outer surface of the web taken up by the take-up roller and is movable depending on the position of the outer surface of the web taken up by the take-up roller, a variable resistor connected so that its resistance value can be changed depending on the position of the contact member, and a take-up motor that rotates the take-up roller to take up the web. The variable resistor Information about the resistance value The rotation amount of the winding motor is controlled based on the a control unit for In the image forming apparatus, the control unit determines whether or not the motor is driven based on a change in the information during a driving period in which the motor is driven. It is characterized by notifying the contents of the abnormality. In view of the above-mentioned problems, an image forming apparatus according to the present invention includes a heating rotor that heats unfixed toner carried on a recording material, a pressure rotor that pressurizes the heating rotor, a fixing nip formed by the heating rotor and the pressure rotor, the fixing nip sandwiching and conveying the recording material carrying unfixed toner through the fixing nip to fix an unfixed toner image on the recording material, a web for collecting toner that has not been fixed to the recording material and adheres to the surface of the heating rotor, a take-up roller that takes up the web used to collect the toner that has adhered to the surface of the heating rotor, and a toner that comes into contact with the outer surface of the web taken up by the take-up roller and is wound around the take-up roller. In an image forming apparatus comprising a contact member that can move according to the position of the outer surface of the web that has been taken up, a variable resistor connected so that its resistance value can be changed depending on the position of the contact member, a winding motor that winds up the web by rotating the winding roller, and a control unit that controls the amount of rotation of the winding motor based on information about the resistance value of the variable resistor, the control unit is characterized in that, during the driving period in which the motor is driven, if the amount of change in the information after the winding roller has rotated a predetermined amount of at least one rotation since acquiring the information is less than a predetermined amount, it notifies the user of an abnormality. In consideration of the above-mentioned problems, an image forming apparatus according to the present invention includes a heating rotor that heats unfixed toner carried on a recording material, a pressure rotor that presses the heating rotor, a fixing nip formed by the heating rotor and the pressure rotor, which sandwiches and conveys the recording material carrying unfixed toner through the fixing nip to fix an unfixed toner image on the recording material, a web for collecting toner that is not fixed to the recording material and adheres to the surface of the heating rotor, a supply roller around which the web is wound and which supplies the web, a take-up roller that takes up the web used to collect the toner that has adhered to the surface of the heating rotor, and a roller that comes into contact with the outer surface of the web wound around the supply roller. In an image forming apparatus comprising: a contact member that is movable according to the position of the outer surface of the web supplied to the supply roller; a variable resistor connected so that its resistance value can be changed according to the position of the contact member; a winding motor that winds up the web by rotating the winding roller; and a control unit that controls the amount of rotation of the winding motor based on information about the resistance value of the variable resistor, the control unit is characterized in that, during a driving period in which the motor is driven, if the amount of change in the information after the winding roller has rotated a predetermined amount of at least one rotation since acquiring the information is less than a predetermined amount, the control unit notifies the user of an abnormality. [Effects of the Invention]

[0012] An object of the image forming apparatus according to the present invention is to suppress degradation of image quality that occurs when an abnormality occurs in which the web is not wound up in a web mechanism that uses a variable resistor. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus. [Figure 2] FIG. 2 is a schematic cross-sectional view of a fixing device and a web unit. [Figure 3] FIG. 4 is a schematic diagram showing the configuration of an outer diameter detection unit. [Figure 4] FIG. 2 is a diagram illustrating a detection circuit for a variable resistor. [Figure 5] FIG. 10 is a diagram showing the relationship between the outer diameter of the wound web and the rotation angle of the variable resistor. [Figure 6]FIG. 10 is a diagram showing the relationship between the detected voltage and the rotation angle of the variable resistor. [Figure 7] FIG. 10 is a schematic cross-sectional view of a fixing device and a web unit in a modified example. [Figure 8] FIG. 10 is a schematic diagram showing the configuration of an outer diameter detection unit in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] Example 1 <Image forming device> Fig. 1 is a schematic diagram showing the configuration of an image forming apparatus 100. As shown in Fig. 1, image forming apparatus 100 has four image forming units, yellow 120a, magenta 120b, cyan 120c, and black 120d, arranged along the direction of movement of intermediate transfer belt 115. First, the process of forming a toner image on intermediate transfer belt 115 will be described using yellow image forming unit 120a as an example.

[0015] The surface of the photosensitive drum 111, which is driven to rotate by the charger 112, is uniformly charged (charging). Then, the exposure device 113 irradiates the surface of the photosensitive drum 111 with a laser in accordance with input image data, forming an electrostatic latent image on the surface of the photosensitive drum 111 (exposure). Then, the development device 114 forms a yellow toner image on the photosensitive drum 111 (development). The primary transfer roller 117 applies a voltage of a polarity opposite to the potential polarity of the yellow toner image to the intermediate transfer belt 115. As a result, the yellow toner on the photosensitive drum 111 is transferred to the intermediate transfer belt 115 (primary transfer). Note that any yellow toner remaining on the photosensitive drum surface without being transferred is scraped off by a toner cleaner and removed from the surface of the photosensitive drum 111. This series of processes is similarly performed for the magenta 120b, cyan 120c, and black 120d. As a result, a full-color toner image is formed on the intermediate transfer belt 115.

[0016] The toner image on the intermediate transfer belt 115 is transported to a secondary transfer portion N2 formed by a pair of secondary transfer rollers 116. In synchronization with the transport timing of the toner image, recording materials S are taken out one by one from a recording material cassette 103 and fed to the secondary transfer portion N2. Then, the toner image on the intermediate transfer belt 115 is transferred onto the recording material S (secondary transfer).

[0017] The recording material S onto which the toner image has been transferred is conveyed to the fixing device 200, where it is fixed (fixed) by heat and pressure. The recording material S onto which the toner image has been fixed is discharged onto a paper discharge tray.

[0018] The image forming apparatus 100 can also form monochrome images. When forming monochrome images, only the black image forming unit 120d of the multiple image forming units is driven.

[0019] Now, double-sided printing will be described, in which images are formed on both sides of a recording material S. After the recording material S with an image formed on one side is discharged from the fixing device 200, it is guided to the paper path 134 by the flapper 132. The recording material S is transported from the paper path 134 to the reversing path 136, and then switched back and transported on the reversing path 136. The recording material S then passes through the double-sided path 137, at which point the recording material S is in an inverted state. The recording material S is then transported again to the secondary transfer section N2, where the toner image is transferred and fixed by the fixing device 200. The recording material S that has been double-sided printed is then discharged to the paper output tray.

[0020] The process from charging to discharging the recording material S with the fixed toner image onto the paper output tray is called an image forming process (print job).The period during which image formation is being performed is called an image forming process (print job).

[0021] <Fixing device> Next, the fixing device 200 of this embodiment will be described with reference to FIG.

[0022] 2, the recording material is conveyed in the direction indicated by the arrow α. The fixing device 200 has a heating rotor 201 having a heat source for heating an unfixed toner image carried on the recording material S, and a pressure rotor 202 that abuts against the outer surface of the heating rotor 201. The pressure rotor 202 urges the heating rotor 201 toward the heating rotor 201, applying pressure, so that the heating rotor 201 and the pressure rotor 202 form a fixing nip N. In the fixing nip N, heat and pressure are applied to the recording material S, thereby fixing the toner image.

[0023] The heating rotor 201 is cylindrically formed from a metal such as aluminum or stainless steel. The heating rotor 201 has excellent thermal conductivity and heat resistance. In this embodiment, the heating rotor 201 has a cylindrical metal core with a rubber layer of a predetermined thickness on the outer surface. The rubber layer has a three-layer structure: a base layer, an elastic layer outside the base layer, and a release layer outside the elastic layer. The base layer is made of polyimide resin (PI), the elastic layer is made of silicone rubber, and the release layer is made of PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin) as a fluororesin. The release layer on the outer surface improves toner separation. The heating rotor 201 has a heater 205 inside. The heater 205 is a heat source for applying heat to the recording material. The heater 205 is a halogen heater, and heat generated by the heater 205 is transferred to the surface of the heating rotor 201. The surface temperature of the heating rotor 201 is detected by a thermistor 206. Fixing is performed when the outer surface temperature of the heating rotor 201 reaches a predetermined target temperature required for fixing. It is preferable that the heating rotor 201 has multiple heaters 205 with different orientation distributions. By having heaters 205 with different orientation distributions, it is possible to change the heat generation area depending on the size of the recording material. Note that the heating means is not limited to a halogen heater, and it may be configured to heat the heating rotor 201 by electromagnetic induction heating (IH), for example. The heating rotor 201 is driven to rotate in the direction of arrow R1 by a motor (not shown).

[0024] The pressure rotor 202 has a cylindrical aluminum core, an elastic layer with a thickness of 1 mm on the outside of the core, and a release layer on the outside of the elastic layer to enhance separation from the toner.

[0025] The pressure rotating body 202 is also rotated in the direction of arrow R2. Therefore, when the recording material S is conveyed to the fixing nip N formed by the pressure rotating body 202 and the heating rotating body 201, heat and pressure are applied to fix the toner image.

[0026] The pressure rotor 202 can be moved by a contact / separation mechanism that moves the pressure rotor 202 into or away from the heating rotor 201. The contact / separation mechanism includes a frame 385 and a drive motor (not shown). The frame 385 is supported by the image forming apparatus 100. The frame 385 supports the pressure rotor 202. The frame 385 is rotated by receiving drive from a drive motor (not shown) around a rotation axis 332 as the rotation axis. When the drive motor (not shown) rotates the frame 385 around the rotation axis 332 in a clockwise direction on the drawing, the pressure rotor 330 moves in the direction of arrow P. As a result, the pressure rotor 202 contacts the pressure rotor 201 in a direction perpendicular to the recording material conveyance direction α (contact state). This forms a fixing nip N. In this embodiment, a total pressure of 2000 N is applied, and the width of the fixing nip N is 24 mm. When the frame 385 is rotated counterclockwise on the paper surface around the rotation axis 332, the pressure rotating body 202 is separated from the pressure rotating body 201 (separated state).

[0027] As explained above, the recording material carrying the unfixed toner image is sandwiched and conveyed by the heating rotor 201 and the pressure rotor 202 in the fixing nip N, where heat and pressure are applied to fix the toner image.

[0028] 2 is configured to form a fixing nip portion using a pair of rollers to perform fixing, but is not limited to this. For example, the fixing device 200 may be configured to suspend the belt member using multiple suspension members such as a fixing belt, a fixing pad, and a heating roller.

[0029] <Web Unit> Next, the web unit 210 or the collection roller 204 will be described with reference to FIG.

[0030] The fixing device fixes the toner on the recording material to the recording material using heat and pressure. If excessive heat is applied to the toner on the recording material, the toner on the recording material will melt excessively, and will not be fixed to the recording material, but will instead adhere to the heating rotor 201. This phenomenon is called hot offset. If the toner that has adhered to the heating rotor 201 due to hot offset is not collected, the heating rotor 201 will continue to rotate, causing the hot offset toner to adhere to and be fixed on the succeeding paper. This can result in image defects in the area where the hot offset toner has fixed.

[0031] To cope with this, a web unit 210 is known for recovering the toner that has been hot offset. The web unit 210 recovers the toner that has adhered to the heating rotator 201. This prevents image defects caused by hot offset.

[0032] The web unit 210 includes a web 212 , a supply roller 211 , a take-up roller 214 , and a pressure roller 213 .

[0033] The collection roller 204 comes into contact with the surface of the heating rotor 201 and is rotated by the rotation of the heating rotor 201. The offset toner is melted by the application of heat in the fixing nip N and adheres to the surface of the heating rotor 201. The collection roller 204 used in this embodiment is a roller with an outer diameter of 20 mm, and is made of stainless steel SUS303, which has a higher affinity for the melted toner than the release layer on the surface of the heating rotor 201. Therefore, the melted toner is moved to the surface of the collection roller 204.

[0034] The toner that has moved to the surface of the recovery roller 204 is collected from the recovery roller 204 by a web 212 made of nonwoven fabric or the like. The web unit 210 has a pressure roller 213 for pressing the web 212 against the recovery roller 204. The pressure roller 213 presses the web 212 against the recovery roller 204, forming a predetermined nip width. The toner that has moved to the recovery roller 204 is collected by the web 212.

[0035] The web 212 used for toner recovery is taken up by the take-up roller 214. In this embodiment, the take-up roller 214 takes up the web 212 at a frequency of, for example, 0.2 mm per four sheets of A4 paper. One side end of the web 212 is taken up by the take-up roller 214, and the other side end is taken up by the supply roller 211. The supply roller 211 has an unused web 212 wound around it, and when the web 212 is taken up by the take-up roller 214, the unused web 212 is supplied from the supply roller 211. As a result, the unused web 212 is supplied to the contact portion between the web 212 and the recovery roller 204, and the toner adhering to the surface of the heating rotor 201 is recovered.

[0036] The web 212 is made of nonwoven fabric or the like, with a total length of approximately 50 m. After the recording material has been fixed, when the web 212 for collecting toner runs out, it must be replaced with a new web. Therefore, when the web 212 for collecting toner runs out, the user of the image forming apparatus 100 calls a service technician, who then replaces the web unit 210 with a new one. The longer the life of the web unit 210, the fewer times the user will need to call a service technician, so it is preferable that the web unit 210 has a long life. A new web here refers to a web that has never been used to collect toner.

[0037] The reason why the web 212 collects toner via the collection roller 204 will be explained. The web 212 is made of nonwoven fabric or the like. Therefore, if the web 212 were to come into direct contact with the heating rotator 201 without the collection roller 204, the surface of the heating rotator 201 would be more susceptible to deterioration. If the surface of the heating rotator 201 were to deteriorate quickly, the heating rotator 201 would need to be replaced more frequently, which would increase the amount of work required. Therefore, by collecting toner via the metal collection roller 204, the web 212 does not come into direct contact with the heating rotator 201, thereby extending the life of the heating rotator 201. Furthermore, unevenness on the surface of the heating rotator 201 affects the gloss of the image formed on the recording material. If the web 212 were to come into direct contact with the surface of the heating rotator 201, unevenness would occur on the heating rotator 201. This could result in uneven gloss in the image formed on the recording material. Therefore, by using a configuration in which the toner is collected via the collection roller 204 and the web 212 does not come into direct contact with the surface of the heating rotator 201, gloss unevenness can be suppressed.

[0038] <Web unit contact mechanism> The web unit 210 has a mechanism (not shown) for moving the web 212 into contact with or away from the collection roller 204. The collection roller 204 also has a mechanism (not shown) for moving the web 212 into contact with or away from the heating rotator 201. When a print job has not been accepted by the control unit 151, the collection roller 204 is separated from the heating rotator 201. When a print job has been accepted, the collection roller 204 comes into contact with the heating rotator 201, and the surface temperature of the collection roller 204 rises. This makes it easier for toner on the surface of the heating rotator 201 to be transferred to the collection roller 204. When the surface temperature of the collection roller 204 becomes sufficiently high, the web 212 comes into contact with the collection roller 204 approximately one second before the recording material is transported to the fixing nip portion. The web 212 remains in contact with the collection roller 204, and the collection roller 204 remains in contact with the heating rotator 201 until the print job is completed.

[0039] When the print job is completed, the web 212 is separated from the collection roller 204 after the last recording material S for the completed print job has passed through the fixing nip portion N.

[0040] [Controlling the rotation amount of the winding roller according to the outer diameter of the wound web] The winding roller 214 is rotated to wind up the used web 212. As the used web 212 is wound, the amount of the web 212 wound onto the winding roller 214 gradually increases, and the outer diameter of the web 212 wound by the winding roller 214 increases. If the rotational speed of the winding roller 214 is kept constant, the larger the outer diameter of the wound web 212, the greater the amount of the web 212 wound up. Therefore, unless the rotational speed of the winding roller 214 is controlled in accordance with the outer diameter of the wound web 212, it is difficult to maintain a constant amount of the web 212 wound up. If the rotational speed of the winding roller 214 is kept constant without taking the outer diameter of the wound web 212 into consideration, the amount of the web 212 wound up gradually increases, resulting in unnecessary use of the web 212 and a shortened lifespan of the web 212.

[0041] Therefore, it has been conventional to control the rotation amount of the winding roller 214 in consideration of the outer diameter of the wound web 212.

[0042] <Winding mechanism using a variable resistor and motor> The following describes how the amount of web 212 to be wound is controlled in accordance with the outer diameter of the wound web 212. First, with reference to Figure 3, the mechanism by which the variable resistor 225 converts the outer diameter of the wound web 212 into a resistance value via the contact member 221 in this embodiment will be described.

[0043] The fixing device 200 has an outer diameter detection unit 220 that detects the outer diameter of the wound web. Figure 3 is a schematic diagram showing an example of the configuration of the outer diameter detection unit 220 in this embodiment. Also, Figure 3(a) shows a state in which the web unit 210 is unused and the web 212 is not yet wound around the winding roller 214. Figure 3(b) shows a state in which the outer diameter of the web 212 wound around the winding roller 214 has increased as a result of the web 212 being wound around the winding roller 214 in the direction of arrow A.

[0044] The contact member 221 of the outer diameter detection unit 220 shown in FIG. 3 has a lever 221a that is biased to contact the outer surface of the wound web 212, and a portion 221b that contacts the link gear 222. The lever 221a of the contact member 221 rotates in the direction of arrow B shown in FIG. 3(b) in accordance with the outer diameter of the wound web 212. This causes 221b of the contact member 221 to rotate in the direction of arrow C, causing the link gear 222 to rotate in the direction of arrow D. The gear portion of the link gear meshes with a stepped gear 223, and when the link gear 222 rotates in the direction of arrow D, the stepped gear 223 rotates in the direction of arrow E. The stepped gear 223 meshes with a gear portion 224 of the variable resistor 225. The gear shaft of the gear portion 224 of the variable resistor 225 is a D-cut shaft and is engaged with a rotating portion 225a of the variable resistor 225. Therefore, when the stepped gear 223 rotates in the direction of arrow E, the rotating portion 225a of the variable resistor 225 rotates in the direction of arrow G. In other words, when the web 212 is wound by the winding roller 214 and the outer diameter of the web 212 increases, the rotating portion 225a of the variable resistor 225 rotates in the direction of arrow G. The resistance value of the variable resistor 225 can be changed by the amount of rotation of the rotating portion 225a. As described above, the variable resistor 225 used in this embodiment is a rotary variable resistor, a so-called rotary volume.

[0045] <Calculating the detection voltage Vsns from the resistance value of the variable resistor> The relationship between the rotating portion 225a of the variable resistor 225 and the resistance value will be described using Figure 4. Figure 4 is a diagram showing a detection circuit for the variable resistor 225 in this embodiment. The variable resistor 225 has terminals 1, 2, and 3. Terminals 1 to 3 of the variable resistor 225 shown in Figure 4 correspond to terminals 1 to 3 of the variable resistor 225 shown in Figure 3. Terminal 2 is connected to the rotating portion 225a. The resistance value R12 between terminals 1 and 2 or the resistance value R23 between terminals 2 and 3 changes depending on the angle (amount of rotation) of the rotating portion 225a.

[0046] Terminals 1 to 3 of variable resistor 225 are connected to control board 150, terminal 1 is connected to GND, terminal 2 is connected to a terminal of control unit 151 as detection voltage Vsns, and terminal 3 is connected to a 3.3V power supply.

[0047] In this embodiment, the total resistance value of the variable resistor between R1 and R3 is set to 10 kΩ, and the angle (amount of rotation) of the rotating portion 225a of the variable resistor 225, the resistance value R12 between terminals 1 and 2, and the resistance value R23 between terminals 2 and 3 are changed. R13=R12+R23=10kΩ...Formula 1 holds true.

[0048] Next, an example of calculating information related to the resistance value of the variable resistor 225 will be shown. In this embodiment, the voltage value is calculated from the resistance value of the variable resistor 225. However, this is not limiting. A method of calculating the current value from the resistance value is also acceptable. In addition, the resistance value of the variable resistor 225 may be stored in the storage unit 152. However, since the resistance value has the characteristic of changing depending on the temperature of the external environment, it is preferable to store the voltage value or the current value in the storage unit 152.

[0049] Since the resistance value is set by variable resistor 225 and terminal 3 is connected to the 3.3V power supply, detection voltage Vsns is input to control unit 151 connected to terminal 2. The detection voltage Vsns is a voltage obtained by dividing the 3.3V power supply by R12 and R23, and is calculated by the following formula. Vsns=3.3V×(R12)÷(R12+R23)...Equation 2 As a result, by using the detection voltage Vsns, the outer diameter of the web 212 wound around the winding roller 214 can be obtained as an electrical detection signal.

[0050] <Relationship between detection voltage and outer diameter of web> Using FIG. 5, the relationship between the rotation angle of the variable resistor 225 and the output voltage value in this embodiment will be described. In this embodiment, the outer diameter of the winding roller 214 is Φ12 mm, and is Φ50 mm when the winding roller 214 runs out of web 212 (when the web 212 reaches the end of its life). The point at which use of the web 212 begins at factory shipment is designated (1), and the rotational angle of the rotating part 225a of the variable resistor 225 at this time is 45°. The detected voltage value at (1) is designated Va. As the web 212 is subsequently used, the outer diameter of the wound web 212 increases, and the resistance value (between R1 and R2) of the variable resistor 225 also increases. This increases the detected voltage Vsns, and when the web 212 reaches the end of its life, it reaches (2). The rotational angle of the rotating part 225a of the variable resistor 225 at (2) is designated 315°, and the detected voltage is designated Vb. The characteristic line connecting (1) and (2) is defined as TYP, and control unit 151 controls the amount of rotation of take-up motor 240 (described later) along TYP.

[0051] The storage unit 152 stores data related to the web 212. The data includes Va, which is the detected voltage at the time of shipping from the factory, and Vb, which is the detected voltage at the end of the life (the voltage value at the end of the life).

[0052] In this embodiment, Vb indicates the time when the web 212 runs out to be wound, and Vb is calculated from the detected voltage Va at the time of shipment from the factory. Therefore, depending on the amount of toner collected by the web 212, the time when the web 212 actually runs out to be wound and the time when the detected voltage Vsns becomes equal to or greater than Vb may not necessarily coincide. In other words, the outer diameter of the wound web 212 also depends on the amount of collected toner. The greater the amount of collected toner, the larger the outer diameter of the wound web 212.

[0053] In this embodiment, Vb indicates the time when there is no more web 212 to be wound up, but is not limited to this. It may also be a value that indicates when the amount of web 212 falls below a predetermined amount and prompts the user to replace the web 212.

[0054] <The web is wound up by the winding motor> Using FIG. 2, the control unit 151 will explain how it controls the take-up motor 240 based on the acquired voltage value. The control unit 151 is electrically connected to the terminals of the variable resistor 225 and can obtain the resistance value of the variable resistor 225. Therefore, the control unit 151 can obtain the detected voltage value Vsns using Equation 2. The control unit 151 is also connected to the take-up motor 240. The "take-up motor 240" here refers to a motor for rotating the take-up roller 214. The control unit 151 controls the rotation amount of the take-up motor 240 based on the acquired detected voltage value Vsns. Specifically, in this embodiment, if the take-up roller 214 can rewind 0.2 mm of the web 212 in one rotation, it is possible to recover toner from the surface of the heating rotator 201 and reduce the risk of image defects on subsequent sheets. Therefore, the desired amount of the web 212 to be rewound in one rotation of the take-up roller 214 is 0.2 mm. As the outer diameter of the wound web 212 increases, the rotation amount of the winding motor 240 is decreased so that the amount of web 212 wound by the winding roller 214 becomes 0.2 mm. At this time, the control unit 151 controls the rotation amount of the winding motor 240 in accordance with the obtained value of Vsns, and rotates the winding motor 240.

[0055] In this embodiment, a stepping motor is used as the winding motor 240. The control unit 151 controls the number of pulses input to the stepping motor, thereby controlling the amount of rotation of the stepping motor and controlling the amount of web 212 to be wound up.

[0056] Furthermore, as the winding motor 240 winds up the web 212, the unused web 212 gradually runs out, and the time to replace the web 212 approaches. By storing Vb, which is the voltage value for prompting the user to replace the web 212, in the memory unit 152, it is possible to determine whether the detected voltage value Vsns has reached Vb. This makes it possible to determine when it is time to replace the web 212.

[0057] The web 212 is a consumable item. When the wound web 212 runs out, it must be replaced with a new web 212. Usually, the web 212 is not replaced alone, but the web unit 210 is replaced as well. Therefore, when it is time to replace the web unit 210, the user calls a service technician to replace the web 212 with a new web 212. When the web 212 is replaced with a new web, the wound web 212 runs out and the outer diameter of the wound portion of the web 212 also disappears. Because the contact member 221 is biased against the outer surface of the wound web 212, Vsns returns to near Va, which is the value at the start of use.

[0058] The variable resistor 225 converts the position of the contact member 221 into a resistance value. A voltage is detected from the converted resistance value, and the winding motor 240 controls the winding roller 214 based on the detected voltage. Compared to a conventional configuration using a solenoid or the like, the configuration using the variable resistor 225 and the winding motor 240 of this embodiment has less contact between the levers. Therefore, errors due to contact between the levers are suppressed, and the generated errors can be reduced. As a result, the web 212 can be wound with high precision, and the life of the web 212 can be extended.

[0059] The effect of control unit 151 using detected voltage Vsns to control take-up motor 240 will be described. Control unit 151 controls the rotational speed of take-up motor 240. In this case, control unit 151 uses detected voltage Vsns instead of resistance value R12 obtained from variable resistor 225. Variable resistor 225 is made of metal. Metals generally tend to have higher electrical resistivity as their temperature increases. Therefore, resistance value R12 obtained from variable resistor 225 changes depending on the temperature of the external environment. For example, if control unit 151 uses resistance value R12 to control the rotational speed of take-up motor 240, the rotational speed will change depending on the temperature of the external environment. As a result, the error in the amount of web 212 being wound will increase. However, it can be said that detected voltage Vsns calculated using Equation 2 is less dependent on the temperature of the external environment than resistance value R12. Therefore, control unit 151 controls take-up motor 240 using detected voltage Vsns. This allows for accurate winding of web 212.

[0060] <Detecting abnormalities using a variable resistor> In the web unit 210 using the variable resistor 225, the winding roller 214 is rotated by a motor 240, and the web 212 is wound.

[0061] Suppose an abnormality occurs in which the take-up roller 214 does not rotate (e.g., a malfunction of the motor 240). As a result, the web 212 does not reel in. Without a means for detecting this abnormality, it is difficult for the user to notice the abnormality. Image formation continues despite the abnormality, and fixing is performed in the fixing device 200. Because the fixing operation is performed with the same area of ​​the web 212 in contact with the recovery roller 204, there is a risk that sufficient toner may not be recovered. As a result, the toner that was not fully recovered may adhere to the subsequent paper, resulting in a deterioration in image quality. Therefore, in this embodiment, the abnormality of the take-up roller 214 not rotating is detected, and the user is notified of the abnormality, thereby preventing a deterioration in image quality. The detection method is described in detail below.

[0062] In the outer diameter detection unit 221, the variable resistor 225 converts the position of the lever 221a into a resistance value via multiple gears. The resistance value of the variable resistor 225 changes depending on the position of the lever 221a. In this embodiment, the larger the outer diameter of the wound web, the larger the resistance value of the variable resistor 225.

[0063] If an abnormality occurs in which the winding roller 214 does not rotate, the outer diameter of the wound web 212 does not increase. Therefore, the resistance value of the variable resistor 225 does not change due to an increase in the outer diameter of the wound web 212. The same applies to the detected voltage Vsns. In this embodiment, if the resistance value does not change by a certain value or more after a predetermined time, the control unit 151 determines that an abnormality has occurred and notifies the user of the abnormality.

[0064] The "predetermined time" in this embodiment will be explained. Here, the predetermined time refers to the time it takes for the take-up roller 240 to make one rotation to wind up the web 212. A method for calculating the time for one rotation will be described. The control unit 151 detects the detected voltage Vsns. Then, from the graphs shown in FIGS. 5 and 6, the control unit 151 obtains the outer diameter of the wound web 212 and obtains the amount of web 212 that is required for the take-up roller 240 to make one rotation. From the obtained amount of web 212 that is wound up, the time until winding is predicted, and in this embodiment, the predicted time is set as the predetermined time. Specifically, in this embodiment, one rotation of the take-up roller 214 is 0.2 mm. Outer diameter Therefore, the predetermined time is the time required to wind up the web 212 of 12 mm at the shortest.

[0065] In this embodiment, a threshold value is set. Even if the take-up roller 214 is not rotating due to an abnormality, the detected voltage Vsns may vary due to an error or the like, and may change after a predetermined time. Therefore, it is preferable to set a threshold value and have the control unit 151 determine whether the amount of change in the detected voltage Vsns before and after the predetermined time exceeds the threshold value, thereby detecting an abnormality. Furthermore, it is preferable that the threshold value be a value larger than the expected error.

[0066] If the detected voltage Vsns exceeds the threshold value after a predetermined time, which is the predicted time, the control unit 151 determines that the take-up roller 214 is rotating normally. On the other hand, if the detected voltage Vsns is equal to or less than the threshold value after a predetermined time, which is the predicted time, the control unit 151 determines that the take-up roller 214 is not rotating. Then, the control unit 151 issues a notification that an abnormality has occurred.

[0067] In this embodiment, the predetermined time is the time it takes for the winding roller 214 to make one rotation, but this is not limited to this. The web 212 is thin. Therefore, even when the variable resistor 225 or the like is used, it may be difficult to detect an increase in the outer diameter of the wound web 212 by the thickness of the web 212. Therefore, in order to make it easier to detect a change in the outer diameter of the wound web 212, it is also possible to predict the time it will take for the winding roller 214 to make one or more rotations, for example, five rotations, and use this as the predetermined time to detect an abnormality.

[0068] Control unit 151 acquires the predetermined time and determines whether the amount of change in detected voltage Vsns before and after the predetermined time exceeds a threshold. This makes it possible to determine whether take-up roller 214 is rotating normally. As a result, it is possible to detect whether an abnormality has occurred in outer diameter detection unit 220, including take-up motor 240.

[0069] When control unit 151 detects an abnormality, such as take-up roller 214 not rotating, it notifies the user of the details of the abnormality. As a means of notifying, it is preferable to display the details of the abnormality on display unit 180. By displaying the details on display unit 180, it is possible to notify the user that an abnormality has occurred. As a result, the user notices the abnormality and it is possible to prevent the fixing operation from continuing in a state in which toner recovery is not satisfactory. In addition, it is possible to take measures such as dispatching a service technician. Note that in addition to displaying the details of the abnormality on display unit 180, a sound may be generated to notify the user of the abnormality. Therefore, the means for leaving the abnormality alone may be any means that allows the user to notice that an abnormality has occurred.

[0070] When the control unit 151 detects an abnormality and issues a notification using the notification means, image formation is suspended. Suspension of image formation refers to the above-mentioned image formation process (print job), and refers to the suspension of the process from charging to discharging the recording material S with the fixed toner image onto the paper output tray. By detecting an abnormality and suspending image formation, it is possible to prevent image formation from being performed after detecting that the web 212 is not being wound up. This makes it possible to prevent a deterioration in image quality.

[0071] When the winding roller 214 is not rotating, the same area of ​​the web 212 comes into contact with the collection roller 204. Because the collection roller 204 rotates following the rotation of the heating rotator 201, there is a risk that the web 212 may be damaged if the same area comes into contact with the collection roller 204. Therefore, it is preferable that the collection roller 204 and the web 212 are configured to separate from each other when the control unit 151 detects an abnormality.

[0072] <Example 2> Next, a second embodiment will be described with reference to Figures 7 and 8. Note that a description of the same aspects as in Example 1 will be omitted.

[0073] FIG. 7 is a schematic cross-sectional view of a fixing device according to the second embodiment, and FIG. 8 is a schematic view of a supply roller outer diameter detection unit according to the second embodiment.

[0074] As shown in Figure 7, in the second embodiment, an outer diameter detector 250 is provided that detects the outer diameter of the web 212 wound around the supply roller. The signal is converted into an electrical signal using a second variable resistor 252, and then output to the control board 150. Figure 8(a) shows a state in which the web unit 210 is unused and the web 212 is not yet fed from the supply roller 211. Figure 8(b) shows a state in which the outer diameter of the web 212 wound around the supply roller 211 has become smaller as the web 212 is fed by the supply roller 211 in the direction of arrow A'.

[0075] The contact member 251 of the outer diameter detection unit 250 of the supply roller shown in FIG. 8 has a lever 251a that is biased to contact the outer surface of the web 212 wound around the wound supply roller 211, and a portion 251b that contacts the link gear 252. The lever 251a of the contact member 251 rotates in the direction of arrow B' shown in FIG. 8(b) in response to the outer diameter of the wound web 212. Then, 251b of the contact member 251 rotates in the direction of arrow C', causing the link gear 222 to rotate in the direction of arrow D'. The gear portion of the link gear meshes with the stepped gear 223, and when the link gear 222 rotates in the direction of arrow D', the stepped gear 223 rotates in the direction of arrow E'. The stepped gear 223 meshes with the gear portion 224 of the variable resistor 225. The gear shaft of the gear portion 224 of the second variable resistor 225 is a D-cut shaft and is engaged with the rotating portion 225a of the variable resistor 225. Therefore, when the stepped gear 223 rotates in the direction of arrow E', the rotating portion 225a of the variable resistor 225 rotates in the direction of arrow G'. In other words, when the take-up roller 214 takes up the web 212 and the outer diameter of the web 212 increases, the rotating portion 225a of the variable resistor 225 rotates in the direction of arrow G'. The resistance value of the variable resistor 225 can be changed by the amount of rotation of the rotating portion 225a. As described above, in the second embodiment, the second variable resistor 225 is used, and the outer diameter of the web 212 wound around the supply roller 211 is detected using a rotary variable resistor, a so-called rotary volume, and a contact member.

[0076] As described above, as the web 212 is used, the outer diameter of the supply roller 211 decreases and the outer diameter of the web take-up roller 214 increases. In each case, the detected voltage Vsns detected by the variable resistor 225 also increases. The outer diameter detector 250 for the supply roller detects a change in the detected voltage Vsns when the web 212 is unwound from the outer periphery of the supply roller 214. Furthermore, the outer diameter detector 220 for the take-up roller detects a change in the detected voltage Vsns when the web 212 makes one revolution around the outer periphery of the take-up roller 214.

[0077] Here, if an abnormality occurs in which the winding roller 214 does not rotate, the outer diameter of the wound web 212 does not increase. Therefore, the resistance value of the variable resistor 225 does not change due to an increase in the outer diameter of the wound web 212. The same applies to the detected voltage Vsns. Furthermore, in the second embodiment, an outer diameter detection unit 250 is provided that detects the outer diameter of the web 212 wound around the supply roller 211. Therefore, if the resistance value does not change by a certain value or more after a predetermined time, the control unit 151 determines that an abnormality has occurred and notifies the user of the abnormality.

[0078] The detected voltage Vsns changes more quickly when the outer diameter of the supply roller 211 or the take-up roller 214 is smaller. In the first embodiment, which does not include the outer diameter detection unit 250 for the supply roller 211, it takes time to detect an abnormality when the outer diameter of the take-up roller 214 becomes larger than the outer diameter of the supply roller 211. However, in the second embodiment, which includes the outer diameter detection unit 250 for the supply roller 211, the control unit 151 can detect an abnormality using the detected voltage Vsns for the roller with the smaller outer diameter, either the supply roller 211 or the take-up roller 214.

[0079] As described above, in the above-described embodiment, if an abnormality occurs in the contact member, winding motor 240, or outer diameter detection unit 220 (250), the abnormality can be quickly detected and reported, even if the web 212 is in the latter half of its lifespan, thereby preventing a decrease in image quality due to the web not being fed. [Explanation of symbols]

[0080] 100 Image forming device 151 Control Unit 180 Display section 200 Fixing device 201 Heating Rotor 202 Pressurized Rotating Body 204 Collection Roller 205 Heater 210 Web Unit 211 Supply roller 212 Web 213 Pressure roller 214 Winding roller 220 Outer diameter detection unit 221 Contact member 225 variable resistor 240 Winding motor

Claims

1. a heating rotor for heating unfixed toner carried on a recording material; a pressure rotating body that pressurizes the heating rotating body; a fixing nip portion is formed by the heating rotary member and the pressure rotary member, and a recording material carrying unfixed toner is nipped and conveyed through the fixing nip portion, thereby fixing the unfixed toner image on the recording material; a web for collecting toner that has not been fixed to the recording material and adheres to the surface of the heating rotary body; a take-up roller that takes up the web used to collect the toner adhering to the surface of the heating rotary body; a contact member that contacts an outer surface of the web wound around the winding roller and is movable according to the position of the outer surface of the web wound around the winding roller; a variable resistor connected so that its resistance value can be changed depending on the position of the contact member; a winding motor that rotates the winding roller to wind up the web; a control unit that controls the rotation amount of the take-up motor based on information about the resistance value of the variable resistor, The image forming apparatus is characterized in that the control unit notifies the user of the abnormality based on the amount of change in the information during the driving period in which the motor is driven.

2. A heating rotor that heats unfixed toner carried on a recording material; a pressure rotating body that pressurizes the heating rotating body; a fixing nip portion is formed by the heating rotary member and the pressure rotary member, and a recording material carrying unfixed toner is nipped and conveyed through the fixing nip portion, thereby fixing the unfixed toner image on the recording material; a web for collecting toner that has not been fixed to the recording material and adheres to the surface of the heating rotary body; a take-up roller that takes up the web used to collect the toner adhering to the surface of the heating rotary body; a contact member that contacts an outer surface of the web wound around the winding roller and is movable according to the position of the outer surface of the web wound around the winding roller; a variable resistor connected so that its resistance value can be changed depending on the position of the contact member; a winding motor that rotates the winding roller to wind up the web; a control unit that controls the rotation amount of the take-up motor based on information about the resistance value of the variable resistor, The control unit is characterized in that, during the driving period in which the motor is driven, if the change in the information after the winding roller has rotated a predetermined amount of at least one rotation since acquiring the information is less than a predetermined amount, the control unit notifies the user of an abnormality.

3. An image forming apparatus as described in claim 1 or 2, characterized in that it is provided with a display unit that displays information regarding the abnormality.

4. 4. The image forming apparatus according to claim 1, further comprising a recovery roller that recovers toner that has not been fixed to the recording material and adheres to the heating rotor from the heating rotor, and the web recovers toner that has adhered to the recovery roller from the recovery roller.

5. 5. The image forming apparatus according to claim 4, wherein the control unit separates the collection roller from the web when notifying the abnormality.

6. 6. The image forming apparatus according to claim 1, wherein the control unit suspends image formation when notifying the content of the abnormality.

7. 7. The image forming apparatus according to claim 1, wherein the control unit obtains a voltage from the resistance value of the variable resistor, and controls the rotation amount of the winding motor based on the obtained voltage.

8. An image forming apparatus as described in any one of claims 1 to 7, characterized in that the contact member has a lever that contacts the outer surface of the web wound around the winding roller, and the lever is connected to the variable resistor via one or more gears.

9. 9. The image forming apparatus according to claim 1, wherein the variable resistor has a rotating portion that rotates in accordance with the movement of the contact member, and the resistance value can be changed according to the amount of rotation of the rotating portion.

10. A heating rotor for heating unfixed toner carried on a recording material; a pressure rotating body that pressurizes the heating rotating body; a fixing nip portion is formed by the heating rotary member and the pressure rotary member, and a recording material carrying unfixed toner is nipped and conveyed through the fixing nip portion, thereby fixing the unfixed toner image on the recording material; a web for collecting toner that has not been fixed to the recording material and adheres to the surface of the heating rotary body; a supply roller around which the web is wound and which supplies the web; a take-up roller that takes up the web used to collect the toner adhering to the surface of the heating rotary body; a contact member that contacts an outer surface of the web wound around the supply roller and is movable according to the position of the outer surface of the web being supplied to the supply roller; a variable resistor connected so that its resistance value can be changed depending on the position of the contact member; a winding motor that rotates the winding roller to wind up the web; a control unit that controls the rotation amount of the take-up motor based on information about the resistance value of the variable resistor, The control unit is characterized in that, during the driving period in which the motor is driven, if the change in the information after the winding roller has rotated a predetermined amount of at least one rotation since acquiring the information is less than a predetermined amount, the control unit notifies the user of an abnormality.

Images