Image forming apparatus

Abstract

To provide an image forming apparatus that can perform, at a desired timing, an operation according to a trouble occurring in a fixing device.SOLUTION: An image forming apparatus has an image forming unit, a motor, and a control unit. The motor drives the image forming unit and outputs a signal of a magnitude according to the value of driving current. The control unit controls the motor in one of a first operation mode and a second operation mode. When the operation mode is the first operation mode, the control unit sets an upper limit and a lower limit of a first range as thresholds. When the operation mode is the second operation mode, the control unit sets an upper limit and a lower limit of a second range as thresholds. When the magnitude of the signal goes out of the first range during the drive of the motor in the first operation mode, the control unit performs a first operation. When the magnitude of the signal goes out of the second range while the motor is driven in the second operation mode, the control unit performs a second operation.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] An embodiment of the present invention relates to an image forming apparatus. [Background technology]

[0002] Conventionally, there is known an image forming apparatus capable of detecting a parameter value indicating the state of a motor that drives a fixing device, and determining whether or not a malfunction has occurred in the fixing device based on the detected parameter value. The parameter indicating the state of the motor is, for example, a torque of the motor, a driving current of the motor, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-040801 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the value of the parameter indicating the state of the motor varies depending on the rotation speed of the motor, etc. Therefore, in the image forming apparatus as described above, for example, when the motor is driven at a rotation speed different from a predetermined rotation speed, it may be difficult to accurately determine whether or not a malfunction has occurred in the fixing device. As a result, the image forming apparatus may not be able to perform an operation corresponding to a malfunction occurring in the fixing device at a desired timing.

[0005] An object of the present invention is to provide an image forming apparatus that can perform an operation in response to a malfunction occurring in the fixing device at a desired timing. [Means for solving the problem]

[0006] The image forming apparatus of the embodiment has a conveying unit, an image forming unit, a fixing device, a motor, and a control unit. The conveying unit conveys a print medium. The image forming unit forms a toner image of a target image on the print medium conveyed by the conveying unit. The fixing device heats the print medium after the toner image has been formed by the image forming unit, and fixes the toner image to the print medium as the target image. The motor drives the fixing device and outputs a signal having a magnitude according to the value of the drive current. The control unit performs a first operation when the magnitude of the signal falls outside a first range while driving the motor in a first operation mode, and performs a second operation when the magnitude of the signal falls outside a second range different from the first range while driving the motor in a second operation mode. [Brief description of the drawings]

[0007] [Figure 1] 1 illustrates an example of a configuration of an image forming apparatus 1. FIG. [Diagram 2] FIG. 2 illustrates an example of a functional configuration of a control unit 100. [Diagram 3] FIG. 4 is a diagram illustrating an example of a first correspondence relationship. [Figure 4] 1 is a diagram showing an example of a flow of a process for performing a first operation or a second operation among the processes performed by the image forming apparatus 1. FIG. [Diagram 5] 5 is a diagram showing an example of the flow of a first abnormality process performed by the control unit 100 in ACT 190 shown in FIG. [Figure 6] 5 is a diagram showing an example of the flow of a second abnormality process performed by the control unit 100 in ACT 220 shown in FIG. [Figure 7] FIG. 11 is a diagram illustrating an example of a second correspondence relationship. [Figure 8] FIG. 11 is a diagram showing an example of a flow of a process for performing a first operation or a second operation among the processes performed by an image forming apparatus 1 according to a fourth modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An image forming apparatus according to an embodiment will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals.

[0009] (Overview of image forming device) An overview of an image forming apparatus according to an embodiment will be described.

[0010] The image forming apparatus according to the embodiment has a conveying section, an image forming section, a fixing device, a motor, and a control section. The conveying section conveys a print medium. The image forming section forms a toner image of a target image on the print medium conveyed by the conveying section. The fixing device heats the print medium after the toner image has been formed by the image forming section, and fixes the toner image to the print medium as a target image. The motor drives the fixing device and outputs a signal having a magnitude according to the value of the drive current. The control section performs a first operation when the motor is driven in a first operation mode and the magnitude of the signal falls outside a first range, and performs a second operation when the motor is driven in a second operation mode and the magnitude of the signal falls outside a second range different from the first range.

[0011] This allows the image forming apparatus according to the embodiment to perform an operation in response to a malfunction occurring in the fixing device at a desired timing.

[0012] (Configuration of Image Forming Apparatus) The configuration of an image forming apparatus according to an embodiment will be described below. As an example of the image forming apparatus, an image forming apparatus 1 will be described. FIG.

[0013] The image forming device 1 is a device that forms an image on a print medium. For example, the image forming device 1 is a multifunction device, a copier, a printer, etc. The print medium is a medium on which the image forming device 1 performs processing such as image formation. The print medium may be any medium as long as it is a sheet-like medium on which an image can be formed on at least one of both sides. For example, the print medium is printing paper, plastic film, etc.

[0014] Image forming apparatus 1 includes, for example, printer unit 11, control panel 12, manual feed tray TA, and paper discharge tray TB. Image forming apparatus 1 may include other members, other devices, etc. in addition to printer unit 11, control panel 12, manual feed tray TA, and paper discharge tray TB.

[0015] The printer section 11 includes a control section 100 , a paper feed cassette 111 , a paper feed cassette 112 , and an image forming unit 114 .

[0016] The control unit 100 controls the entire image forming apparatus 1. In other words, the control unit 100 controls the printer unit 11, the control panel 12, and the image forming unit 114.

[0017] The paper feed cassette 111 stores a type of print medium desired by the user. For example, the paper feed cassette 111 stores A4 size plain paper.

[0018] The paper feed cassette 112 stores a type of print medium desired by the user. For example, the paper feed cassette 112 stores A4-sized thick paper.

[0019] The control panel 12 includes an operation receiving section and a display section.

[0020] The operation reception unit receives an operation from a user. The operation reception unit is an input device. For example, the operation reception unit is a touch pad, an input key, etc. When the operation reception unit receives an operation from a user, the operation reception unit outputs information indicating the received operation to the control unit 100.

[0021] The display unit displays an image according to the operation received via the operation receiving unit. The display unit is an image display device. For example, the display unit is a liquid crystal display, an organic EL (Electro Luminescence) display, or the like. The display unit may be integrated with the operation receiving unit as a touch panel.

[0022] Image forming unit 114 conveys the print medium and forms an image indicated by image data acquired from control unit 100 on the print medium in accordance with control from control unit 100. For ease of explanation, forming an image on the print medium will be referred to as printing. Image forming unit 114 is an example of an image forming section.

[0023] (Configuration of Image Forming Unit) The configuration of the image forming unit 114 will be described.

[0024] The image forming unit 114 includes an intermediate transfer belt 20. The image forming unit 114 includes a driven roller 21, a backup roller 22, a secondary transfer roller 23, two registration rollers 24, and a manual feed roller 25. The image forming unit 114 includes four image forming stations, namely, an image forming station 31, an image forming station 32, an image forming station 33, and an image forming station 34. The image forming unit 114 includes a belt cleaner 40, a first detection unit 41, a second detection unit 42, and a third detection unit 43. The image forming unit 114 includes a fixing device AD, a motor MT, and a double-sided printing device DF.

[0025] The intermediate transfer belt 20 is a belt onto which a toner image is primarily transferred by four sets of image forming stations. That is, a toner image is formed on the intermediate transfer belt 20. The intermediate transfer belt 20 is supported by a driven roller 21, a backup roller 22, etc. The intermediate transfer belt 20 rotates in the direction indicated by the arrow m in FIG. 1. More specifically, the image forming unit 114 rotates the intermediate transfer belt 20 in that direction by a motor (not shown) in response to control from the control unit 100.

[0026] The image forming station 31 is an image forming station for forming a Y (yellow) image. The image forming station 32 is an image forming station for forming an M (magenta) image. The image forming station 33 is an image forming station for forming a C (cyan) image. The image forming station 34 is an image forming station for forming a K (black) image. In the image forming unit 114, these four sets of image forming stations are arranged below the intermediate transfer belt 20 along the rotation direction of the intermediate transfer belt 20.

[0027] The image forming station 31 includes a photoconductor drum 311, an electrostatic charger 312, an exposure scanning head 313, a developing device 314, a photoconductor cleaner 315, and a primary transfer roller 316. In the image forming station 31, the electrostatic charger 312, the exposure scanning head 313, the developing device 314, the photoconductor cleaner 315, and the primary transfer roller 316 are arranged around the photoconductor drum 311 which rotates in the direction indicated by the arrow n in Fig. 1. The primary transfer roller 316 faces the photoconductor drum 311 via the intermediate transfer belt 20.

[0028] The configurations of the image forming stations 32, 33, and 34 are similar to that of the image forming station 31. Therefore, in the following, descriptions of the configurations of the image forming stations 32, 33, and 34 will be omitted.

[0029] The secondary transfer roller 23 faces the backup roller 22 via the intermediate transfer belt 20. The secondary transfer roller 23 secondarily transfers the toner image, which has been primarily transferred onto the intermediate transfer belt 20, onto a print medium passing between the secondary transfer roller 23 and the intermediate transfer belt 20.

[0030] The two registration rollers 24 transport the print media taken out by a transport mechanism (not shown) from the paper feed cassette 111, the paper feed cassette 112, and the manual feed tray TA between the secondary transfer roller 23 and the intermediate transfer belt 20.

[0031] The manual feed rollers 25 take out the print medium from the manual feed tray TA and transport it to the two registration rollers 24 .

[0032] The belt cleaner 40 removes the toner remaining on the intermediate transfer belt 20 under the control of the control unit 100 .

[0033] The first detection unit 41 is a sensor that detects that the print medium has passed between the two registration rollers 24. In the embodiment, the print medium passing between the two registration rollers 24 means that the print medium is transported by the two registration rollers 24. The first detection unit 41 is provided at a position where it can detect that the print medium has passed between the two registration rollers 24. The first detection unit 41 is, for example, an optical sensor. Instead of an optical sensor, the first detection unit 41 may be another sensor that can detect that the print medium has passed between the two registration rollers 24. When the first detection unit 41 detects that the print medium has passed between the two registration rollers 24, it outputs information indicating that it has detected that the print medium has passed between the two registration rollers 24 to the control unit 100.

[0034] The second detection unit 42 is a sensor that detects that the print medium has passed between the secondary transfer roller 23 and the intermediate transfer belt 20. In the embodiment, the passage of the print medium between the secondary transfer roller 23 and the intermediate transfer belt 20 means that the print medium is transported by the secondary transfer roller 23. The second detection unit 42 is provided at a position where it can detect that the print medium has passed between the secondary transfer roller 23 and the intermediate transfer belt 20. The second detection unit 42 is, for example, an optical sensor. Instead of an optical sensor, the second detection unit 42 may be another sensor that can detect that the print medium has passed between the secondary transfer roller 23 and the intermediate transfer belt 20. When the second detection unit 42 detects that the print medium has passed between the secondary transfer roller 23 and the intermediate transfer belt 20, it outputs information indicating that it has detected that the print medium has passed between the secondary transfer roller 23 and the intermediate transfer belt 20 to the control unit 100.

[0035] The third detection unit 43 is a sensor that detects that the print medium has been discharged to the discharge tray TB. The third detection unit 43 is provided at a position where it can detect that the print medium has been discharged to the discharge tray TB. The third detection unit 43 is, for example, an optical sensor. Instead of an optical sensor, the third detection unit 43 may be another sensor that can detect that the print medium has been discharged to the discharge tray TB. When the third detection unit 43 detects that the print medium has been discharged to the discharge tray TB, it outputs information indicating that it has detected that the print medium has been discharged to the discharge tray TB to the control unit 100.

[0036] The fixing device AD ​​includes a fixing member ADA, a heating section HT, a pressing member ADB, and a pressing force adjusting mechanism ADC.

[0037] The fixing member ADA is a member having an endless peripheral surface. For example, the fixing member ADA is a belt-shaped member. The fixing member ADA abuts against the outer peripheral surface of the pressing member ADB. The fixing member ADA rotates together with the pressing member ADB with which it abuts. A heating section HT is provided inside the fixing member ADA. A support member that rotatably supports the fixing member ADA is provided inside the fixing member ADA. In FIG. 1, the support member is omitted to simplify the drawing.

[0038] The heating section HT heats the fixing member ADA. For example, the heating section HT includes a heater and a heated member that is heated by the heater. In this case, the heated member is in slidable contact with the fixing member ADA. The heating section HT heats the heated member by the heater, and heats the fixing member ADA that is in contact with the heated member.

[0039] The pressing member ADB is a roller that comes into contact with the outer circumferential surface of the fixing member ADA. The driving force of the motor MT is transmitted to the pressing member ADB via gears or the like. In other words, the pressing member ADB is rotated by the driving of the motor MT.

[0040] The pressing member ADB is pressed against the outer peripheral surface of the fixing member ADA by a biasing member such as a spring. The pressing member ADB forms a nip with the fixing member ADA by being pressed against the fixing member ADA. In other words, the pressing member ADB forms a nip with the fixing member ADA by contacting the fixing member ADA. The force with which the pressing member ADB is pressed against the fixing member ADA by the biasing member is adjusted by the control unit 100 via the pressure adjustment mechanism ADC. For convenience of explanation, this force will be referred to as a pressing force. In the fixing device AD, instead of a configuration in which the pressing member ADB is pressed against the outer peripheral surface of the fixing member ADA by the biasing member, a configuration in which the fixing member ADA is pressed against the outer peripheral surface of the pressing member ADB by the biasing member may be used. In this case, the pressing force is the force with which the fixing member ADA is pressed against the pressing member ADB by the biasing member.

[0041] The pressing force adjustment mechanism ADC adjusts the pressing force by moving the pressing member ADB in a direction moving the pressing member ADB away from the fixing member ADA in response to control from the control unit 100. For example, the pressing force adjustment mechanism ADC moves the pressing member ADB in a direction moving the pressing member ADB away from the fixing member ADA, and separates the pressing member ADB from the fixing member ADA. In this case, the pressing force is 0 N. For example, the pressing force adjustment mechanism ADC moves the pressing member ADB in a direction moving the pressing member ADB away from the fixing member ADA, and makes the pressing force coincident with the force in response to control from the control unit 100. In the case where the fixing member ADA is configured to be pressed against the outer peripheral surface of the pressing member ADB by a biasing member, the pressing force adjustment mechanism ADC adjusts the pressing force by moving the fixing member ADA in a direction moving the fixing member ADA away from the pressing member ADB in response to control from the control unit 100.

[0042] The fixing device AD ​​is a device that fixes the toner image onto the print medium after the toner image has been secondarily transferred onto it by the secondary transfer roller 23. More specifically, the fixing device AD ​​applies pressure and heat to the print medium while transporting it using the fixing member ADA and the pressing member ADB. In this way, the fixing device AD ​​fixes the toner image that has been secondarily transferred onto the print medium onto the print medium. As a result, an image is formed on the print medium.

[0043] The motor MT drives the fixing device AD. The motor MT includes a circuit that outputs a signal having a magnitude corresponding to the value of the driving current of the motor MT to the control unit 100. The circuit may be any circuit that can output the signal to the control unit 100. The motor MT is, for example, a servo motor. The motor MT rotates the pressing member ADB via gears or the like. Instead of a servo motor, the motor MT may be another type of motor that can be controlled by the control unit 100.

[0044] The double-sided printing device DF is a device that conveys the print medium after an image has been formed on the front side by the fixing device AD ​​to two registration rollers 24. The print medium is conveyed to the double-sided printing device DF after the front side and back side are turned over. Therefore, the print medium conveyed between the two registration rollers 24 via the double-sided printing device DF has an image formed on the back side via the secondary transfer roller 23 and the fixing device AD.

[0045] (Image forming unit operation) The operation of the image forming unit 114 will now be described.

[0046] First, the operation of the four image forming stations will be described by taking the operation of the image forming station 31 as an example.

[0047] In the image forming station 31, the photoconductor drum 311 is charged by the charging device 312, and then exposed by the exposure scanning head 313. As a result, the image forming station 31 forms an electrostatic latent image on the photoconductor drum 311. Thereafter, the image forming station 31 causes the developing device 314 to develop the electrostatic latent image on the photoconductor drum 311. The developing device 314 develops the electrostatic latent image on the photoconductor drum 311 into a toner image using a two-component developer formed of toner and carrier. In this manner, a toner image is formed on the photoconductor drum 311. The primary transfer roller 316 primarily transfers the toner image formed on the photoconductor drum 311 to the intermediate transfer belt 20. After this primary transfer, the photoconductor cleaner 315 removes the toner remaining on the photoconductor drum 311.

[0048] Each of image forming stations 31, 32, 33, and 34 forms a color toner image on intermediate transfer belt 20 by a primary transfer roller 316. The color toner image is formed by sequentially overlapping toner images of Y (yellow), M (magenta), C (cyan), and K (black).

[0049] Next, the operation of the secondary transfer roller 23 will be described. The secondary transfer roller 23 performs secondary transfer of the color toner images on the intermediate transfer belt 20 all at once onto the print medium passing between the secondary transfer roller 23 and the intermediate transfer belt 20. In the following description, the term "toner image" may refer to either a color toner image or a toner image of only one color. The toner image may be a toner image using a decolorizable toner.

[0050] Next, the operation of conveying the print medium among the operations of the image forming unit 114 will be described.

[0051] At the nip between the two registration rollers 24, the print medium taken out from each of the paper feed cassettes 111, 112, and manual feed tray TA is bent by a transport mechanism (not shown). This aligns the leading edge of the print medium. The two registration rollers 24 then transport the print medium between the secondary transfer roller 23 and intermediate transfer belt 20 in accordance with the timing at which the image forming unit 114 transfers the toner image onto the print medium. The transport paths along which the print media taken out from each of the paper feed cassettes 111, 112, and manual feed tray TA are transported to the two registration rollers 24 join at a junction PA shown in FIG. 1.

[0052] In the image forming unit 114, three transport paths, transport paths LA, LB, and LC, are formed by two registration rollers 24, fixing device AD, and multiple rollers in double-sided printing device DF. Transport path LA is a transport path from junction PA to branching point PB shown in FIG. 1. Transport path LB is a transport path that passes through double-sided printing device DF, and is a transport path from branching point PB to junction point PA. Transport path LC is a transport path from branching point PB to paper discharge tray TB.

[0053] The two registration rollers 24 start rotating in accordance with the position of the toner image on the rotating intermediate transfer belt 20, and move the print medium to the position of the secondary transfer roller 23. As a result, the toner image formed on the intermediate transfer belt 20 is secondarily transferred to the print medium by the secondary transfer roller 23. After the toner image is secondarily transferred to the print medium, the secondary transfer roller 23 transports the print medium along the transport path LA to the fixing device AD. The fixing device AD ​​fixes the toner image secondarily transferred to the print medium transported from the secondary transfer roller 23 to the print medium while transporting the print medium. As a result, the toner image that was secondarily transferred is formed as an image on the print medium. After the image is formed on the print medium, the fixing device AD ​​transports the print medium to the transport path LC. The print medium transported to the transport path LC is then discharged by rollers not shown.

[0054] In the case of double-sided printing, after an image is formed on the front side and the entire print medium passes through the branching portion PB, rollers (not shown) switch back to transport the print medium to the transport path LB. This causes the front and back sides of the print medium to be turned over. Then, multiple rollers in the double-sided printing device DF transport the print medium along the transport path LB to the nip between the two registration rollers 24. The print medium with the turned over front and back sides is then transported along the transport path LA via the two registration rollers 24, where the toner image is fixed by the fixing device AD. As a result, an image is formed on the back side of the print medium. The fixing device AD ​​transports the print medium with the image formed on the back side to the transport path LC and discharges it.

[0055] In this manner, the secondary transfer roller 23, the two registration rollers 24, the fixing device AD, and various rollers within the double-sided printing device DF constitute a transport section that transports the print medium in the image forming apparatus 1.

[0056] (Functional configuration of the control unit) The functional configuration of the control unit 100 will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of the functional configuration of the control unit 100.

[0057] 2, the control unit 100 is communicably connected to each of the printer unit 11 and the control panel 12. The control unit 100 includes a calculation unit 1101, a storage device 1102, a data receiving unit 1103, and an image data developing unit 1104.

[0058] The arithmetic device 1101 is, for example, a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), etc. The arithmetic device 1101 controls the printer unit 11 and the control panel 12 according to an image processing program stored in a storage device 1102.

[0059] The storage device 1102 is a read only memory (ROM), a random access memory (RAM), a hard disk drive (HDD), a solid state drive (SSD), etc. The storage device 1102 may be a separate entity from the control unit 100.

[0060] A data receiving unit 1103 receives print data (eg, data written in a page description language) indicating an image to be printed from a host such as a PC (Personal Computer), and stores the received print data in a storage device 1102 .

[0061] The image data expansion unit 1104 determines printing conditions from the print data stored in the memory device 1102 by the data receiving unit 1103, and expands the data into data that can be printed by the printer unit 11 (e.g., raster data, etc.) and stores it in the memory device 1102.

[0062] (Operation mode of image forming device) The following describes the operation modes of the image forming apparatus 1. The image forming apparatus 1 can perform an operation of forming an image on a print medium in one of a plurality of operation modes depending on the type of print medium. As an example, a case will be described in which the image forming apparatus 1 performs an operation of forming an image on a print medium in one of a first operation mode and a second operation mode depending on the type of print medium.

[0063] The first operation mode is an operation mode in which the motor MT is driven at a first rotation speed. For example, when forming an image on A4-sized plain paper, the image forming apparatus 1 performs an operation of forming an image on the plain paper in the first operation mode. The first rotation speed is, for example, 1500 rpm. The first rotation speed may be a rotation speed slower than 1500 rpm or may be a rotation speed faster than 1500 rpm.

[0064] The second operation mode is an operation mode in which the motor MT is driven at a second rotation speed. For example, when forming an image on A4 size thick paper, the image forming apparatus 1 performs an operation of forming an image on the thick paper in the second operation mode. The second rotation speed is, for example, 940 rpm. The second rotation speed may be a rotation speed slower than 940 rpm or may be a rotation speed faster than 940 rpm.

[0065] (Relationship between the motor drive current and the magnitude of the signal output from the motor) The relationship between the value of the drive current of the motor MT and the magnitude of the signal output from the motor MT will be described. For convenience of explanation, the value of the drive current of the motor MT will be referred to as the drive current value. For convenience of explanation, the signal will be referred to as the motor signal. For convenience of explanation, the magnitude of the motor signal will be referred to as the motor signal value. For convenience of explanation, the relationship between the drive current value and the motor signal value will be referred to as a first correspondence relationship. FIG. 3 is a diagram showing an example of the first correspondence relationship.

[0066] The horizontal axis of the graph shown in FIG. 3 indicates the drive current value. The drive current value changes depending on the load of the motor MT. For example, when the fixing device AD ​​driven by the motor MT is operating normally, the drive current value indicates a value within the normal range shown in FIG. 3. For example, when a contact failure occurs between the fixing member ADA and the pressing member ADB in the fixing device AD ​​driven by the motor MT, the drive current value indicates a value within the first abnormal range shown in FIG. 3. For example, when a lubricant in the fixing member ADA is depleted in the fixing device AD ​​driven by the motor MT, the drive current value indicates a value within the second abnormal range shown in FIG. 3.

[0067] The vertical axis of the graph shown in Fig. 3 indicates the motor signal value. The motor signal value changes according to a combination of the drive current value and the rotation speed of the motor MT. The solid line plotted on the graph indicates the first correspondence relationship when the image forming apparatus 1 operates in the first operation mode. The dotted line plotted on the graph indicates the first correspondence relationship when the image forming apparatus 1 operates in the second operation mode.

[0068] As shown in FIG. 3, when the image forming apparatus 1 is operating in the first operation mode, the motor signal value corresponding to the drive current value indicating the boundary between the normal range and the first abnormal range is different from when the image forming apparatus 1 is operating in the second operation mode. In the example shown in FIG. 3, the motor signal value corresponding to the drive current value indicating the boundary when the image forming apparatus 1 is operating in the first operation mode is larger than the motor signal value corresponding to the drive current value indicating the boundary when the image forming apparatus 1 is operating in the second operation mode. In FIG. 3, the motor signal value corresponding to the drive current value indicating the boundary when the image forming apparatus 1 is operating in the first operation mode is indicated by a threshold value THAB. In FIG. 3, the motor signal value corresponding to the drive current value indicating the boundary when the image forming apparatus 1 is operating in the second operation mode is indicated by a threshold value THBB. On the other hand, in this example, the motor signal value corresponding to the drive current value indicating the boundary when the image forming apparatus 1 is operating in the second operation mode is smaller than the motor signal value corresponding to the drive current value indicating the boundary when the image forming apparatus 1 is operating in the second operation mode. In FIG. 3, the motor signal value corresponding to the drive current value indicating the boundary when the image forming apparatus 1 is operating in the first operation mode is indicated by the threshold value THAA. In FIG. 3, the motor signal value corresponding to the drive current value indicating the boundary when the image forming apparatus 1 is operating in the second operation mode is indicated by the threshold value THBA. For convenience of explanation, the range from the threshold value THAA to the threshold value THAB will be referred to as the first range. For convenience of explanation, the range from the threshold value THBA to the threshold value THBB will be referred to as the second range. The second range is a range in which at least one of the upper limit value and the lower limit value is different from the first range. In the example shown in FIG. 3, the second range is different from the first range in both the upper limit value and the lower limit value.

[0069] (Processing of performing the first operation or the second operation among the processing performed by the image forming apparatus) Among the processes performed by the image forming apparatus 1, the process of performing the first operation or the second operation will be described.

[0070] The first operation is an operation that includes an operation related to the motor signal value being out of the first range among the operations performed by the image forming apparatus 1 in the first operation mode. For example, the first operation includes an operation of outputting notification information to an information processing apparatus communicably connected to the image forming apparatus 1. This notification information includes, for example, information indicating that the motor signal value is out of the first range, information indicating that a malfunction has occurred in the fixing device AD, and the like. For example, the first operation includes an operation of stopping the formation of an image on a print medium. For example, the first operation includes an operation of stopping the driving of the fixing device AD. The first operation may be configured to include other operations instead of some or all of these operations, or in addition to all of these operations.

[0071] The second operation is an operation including an operation related to the motor signal value being out of the second range among the operations performed by the image forming apparatus 1 in the second operation mode. For example, the second operation includes an operation of outputting notification information to an information processing apparatus communicably connected to the image forming apparatus 1. This notification information includes, for example, information indicating that the motor signal value is out of the second range, information indicating that a malfunction has occurred in the fixing device AD, and the like. For example, the second operation includes an operation of stopping the formation of an image on a print medium. For example, the second operation includes an operation of stopping the driving of the fixing device AD. The second operation may include other operations instead of some or all of these operations, or in addition to all of these operations. Some or all of the operations among the one or more operations included in the second operation may be the same as the one or more operations included in the first operation, or may be different from the one or more operations included in the first operation.

[0072] 4 is a diagram showing an example of a flow of a process for performing a first operation or a second operation among the processes performed by the image forming apparatus 1. For convenience of explanation, an image formed on a print medium by the image forming apparatus 1 will be referred to as a target image.

[0073] The control unit 100 waits until the printing operation starts (ACT110). For example, when the control unit 100 receives a print job, it determines to start the printing operation. In this case, the print job includes information indicating the type of print medium on which the target image is to be formed. In the embodiment, the printing operation is an operation performed by the image forming device 1, including transporting the print medium and forming the target image on the print medium. In the flowchart shown in FIG. 4, the flow of the process of performing the printing operation among the processes performed by the image forming device 1 is omitted.

[0074] When the control unit 100 determines to start the printing operation (ACT110-YES), it identifies the type of print medium on which the target image is to be formed based on information included in the print job. After identifying the type, the control unit 100 sets the operation mode of the image forming apparatus 1 to an operation mode corresponding to the identified type. After setting the operation mode of the image forming apparatus 1, the control unit 100 starts the printing operation and also starts a contact operation (ACT120). The contact operation is an operation performed by the image forming apparatus 1 to contact the pressing member ADB with the outer peripheral surface of the fixing member ADA in the fixing device AD. In ACT120, the control unit 100 controls the pressing force adjustment mechanism ADC to start the contact operation.

[0075] Next, the control unit 100 waits until the contact operation started in ACT120 is completed (ACT130). For example, when the pressing force coincides with a predetermined force, the control unit 100 determines that the contact operation is completed. For example, the control unit 100 may be configured to detect the pressing force by a pressure sensor, may be configured to detect the pressing force based on the position of the pressing member ADB, or may be configured to detect the pressing force by another method.

[0076] When the control unit 100 determines that the contact operation started in ACT120 is completed (ACT130-YES), the control unit 100 sets a threshold value (ACT140). Specifically, in ACT140, the control unit 100 sets a threshold value according to the current operation mode of the image forming apparatus 1 as the threshold value for the motor signal value. For example, when the current operation mode of the image forming apparatus 1 is the first operation mode, the control unit 100 sets the threshold value THAA, which is the upper limit value of the first range, and the threshold value THAB, which is the lower limit value of the first range, as the threshold value for the motor signal value. This allows the control unit 100 to determine whether the motor signal value has fallen outside the first range, which is the range from the threshold value THAA to the threshold value THAB. For example, when the current operation mode of the image forming apparatus 1 is the second operation mode, the control unit 100 sets the threshold value THBA, which is the upper limit value of the second range, and the threshold value THBB, which is the lower limit value of the second range, as the threshold value for the motor signal value. This enables the control unit 100 to determine whether or not the motor signal value falls outside the second range, which is the range from the threshold value THBA to the threshold value THBB.

[0077] Next, the control unit 100 drives the motor MT at a rotation speed corresponding to the current operation mode of the image forming apparatus 1, and starts rotating the pressing member ADB (ACT150). In other words, the control unit 100 starts driving the fixing device AD ​​in ACT150. For example, in ACT150, when the current operation mode of the image forming apparatus 1 is the first operation mode, the control unit 100 drives the motor MT at 1500 rpm. For example, in ACT150, when the current operation mode of the image forming apparatus 1 is the second operation mode, the control unit 100 drives the motor MT at 940 rpm.

[0078] Next, the control unit 100 controls the heater of the heating unit HT to start heating the fixing member ADA (ACT160).

[0079] Next, the control unit 100 acquires the motor signal, and determines whether or not the motor signal value of the acquired motor signal is smaller than the lower limit value set in ACT 140 (ACT 170). The lower limit value is the smaller of the threshold values ​​set by the control unit 100 in ACT 140.

[0080] When the control unit 100 determines that the motor signal value of the acquired motor signal is smaller than the lower limit value set in ACT140 (ACT170-YES), it stores contact failure information in the storage device 1102 (ACT180). The contact failure information is information including information indicating that a contact failure has occurred between the fixing member ADA and the pressing member ADB in the fixing device AD ​​driven by the motor MT. The contact failure information may be configured to include other information in addition to information indicating that a contact failure has occurred between the fixing member ADA and the pressing member ADB in the fixing device AD ​​driven by the motor MT.

[0081] Next, the control unit 100 performs the first abnormality processing (ACT190). The first abnormality processing is processing to perform the 11th or 12th operation as an operation corresponding to the current operation mode of the image forming apparatus 1. The 11th operation is the first operation performed in the first abnormality processing by the image forming apparatus 1 operating in the first operation mode. The 12th operation is the second operation performed in the first abnormality processing by the image forming apparatus 1 operating in the second operation mode. The flow of processing by the image forming apparatus 1 to perform the first abnormality processing will be described later. After performing the first abnormality processing, the control unit 100 ends the processing of the flowchart shown in FIG. 4.

[0082] On the other hand, when the control unit 100 determines that the motor signal value of the acquired motor signal is equal to or greater than the lower limit value set in ACT 140 (ACT 170-NO), it determines whether or not the motor signal value of the acquired motor signal is greater than the upper limit value set in ACT 140 (ACT 200). The upper limit value is the larger of the threshold values ​​set by the control unit 100 in ACT 140.

[0083] When the control unit 100 determines that the motor signal value of the acquired motor signal is greater than the upper limit value set in ACT140 (ACT200-YES), it stores lubricant depletion information in the storage device 1102 (ACT210). The lubricant depletion information is information including information indicating that the lubricant in the fixing member ADA in the fixing device AD ​​driven by the motor MT has depleted. The lubricant depletion information may include other information in addition to the information indicating that the lubricant in the fixing member ADA in the fixing device AD ​​driven by the motor MT has depleted.

[0084] Next, the control unit 100 performs the second abnormality processing (ACT220). The second abnormality processing is processing to perform the 21st or 22nd operation as an operation corresponding to the current operation mode of the image forming apparatus 1. The 21st operation is the first operation performed in the second abnormality processing by the image forming apparatus 1 operating in the first operation mode. The 22nd operation is the second operation performed in the second abnormality processing by the image forming apparatus 1 operating in the second operation mode. The flow of processing by the image forming apparatus 1 to perform the second abnormality processing will be described later. After performing the second abnormality processing, the control unit 100 ends the processing of the flowchart shown in FIG. 4.

[0085] On the other hand, when the control unit 100 determines that the motor signal value of the acquired motor signal is equal to or less than the upper limit value set in ACT140 (ACT200-NO), it determines whether or not the printing operation started in ACT120 has ended (ACT230). For example, when the control unit 100 acquires information from the third detection unit 43 indicating that it has detected that the print medium has been discharged to the paper discharge tray TB, it determines that the printing operation has ended. On the other hand, when the control unit 100 does not acquire information from the third detection unit 43 indicating that it has detected that the print medium has been discharged to the paper discharge tray TB, it determines that the printing operation has not ended. The control unit 100 may be configured to determine whether or not the printing operation has ended by another method.

[0086] If the control unit 100 determines that the printing operation started in ACT120 has not finished (ACT230-NO), it transitions to ACT170, acquires a motor signal, and again determines whether the motor signal value of the acquired motor signal is smaller than the lower limit value set in ACT140.

[0087] On the other hand, when the control unit 100 determines that the printing operation started in ACT120 has ended (ACT230-YES), it ends the process of the flowchart shown in FIG.

[0088] (First abnormality processing) The first abnormality process will be described. FIG. 5 is a diagram showing an example of the flow of the first abnormality process performed by the control unit 100 in ACT190 shown in FIG. 4. The operations of the image forming apparatus 1 performed by the processes of ACT310, ACT320, ACT330, ACT340, ACT350, and ACT370 shown in FIG. 5 are an example of the eleventh operation. The operations of the image forming apparatus 1 performed by the processes of ACT310, ACT320, ACT330, ACT340, ACT350, and ACT380 shown in FIG. 5 are an example of the twelfth operation. That is, the operations of the image forming apparatus 1 performed by the processes of ACT310, ACT320, ACT330, ACT340, and ACT350 shown in FIG. 5 are common to both the eleventh operation and the twelfth operation.

[0089] The control unit 100 controls the heater of the heating unit HT to stop heating the fixing member ADA (ACT310).

[0090] Next, the control unit 100 controls the motor MT to stop the rotation of the pressing member ADB (ACT320).

[0091] Next, the control unit 100 stops the printing operation started in ACT120 shown in FIG. 4 (ACT330).

[0092] Next, the control unit 100 transmits the first abnormality notification information (ACT340). The first abnormality notification information is, for example, information including contact failure information. Instead of or in addition to the contact failure information, the first abnormality notification information may be information including information indicating that the motor signal value is out of the first range. The first abnormality notification information may be configured to include other information in addition to either one or both of these two pieces of information. The destination to which the control unit 100 transmits the first abnormality notification information in ACT340 is an information processing device or the like communicably connected to the image forming apparatus 1. The information processing device is, for example, a PC (Personal Computer) of a company that performs maintenance on the image forming apparatus 1, an information processing terminal of an administrator that manages the image forming apparatus 1, or the like, but is not limited to these. The information processing terminal is, for example, a multi-function mobile phone terminal (smartphone), a mobile phone terminal, a tablet PC, a notebook PC, a PDA (Personal Digital Assistant), a desktop PC, or the like, but is not limited to these. The first abnormality notification information is an example of the notification information described above.

[0093] Next, the control unit 100 displays the first abnormality notification information (ACT350). In ACT350, the control unit 100 displays the first abnormality notification information on a display unit of the control panel 12, a display unit of an information processing device communicably connected to the image forming apparatus 1, etc. The information processing device is, for example, a PC in a company that performs maintenance on the image forming apparatus 1, an information processing terminal of an administrator that manages the image forming apparatus 1, etc., but is not limited to these.

[0094] Next, the control unit 100 determines whether the current operation mode of the image forming apparatus 1 is the first operation mode or not (ACT360).

[0095] When the control unit 100 determines that the current operation mode of the image forming apparatus 1 is the first operation mode (ACT360-YES), it performs a first additional operation (ACT370). The first additional operation may be any operation that can be additionally performed by the image forming apparatus 1 operating in the first operation mode in addition to the operations of the image forming apparatus 1 performed by the processes of ACT310, ACT320, ACT330, ACT340, and ACT350 shown in Fig. 5. After performing the process of ACT370, the control unit 100 ends the process of the flowchart shown in Fig. 5.

[0096] On the other hand, when the control unit 100 determines that the current operation mode of the image forming apparatus 1 is the second operation mode (ACT360-NO), it performs a second additional operation (ACT380). The second additional operation may be any operation that can be additionally performed by the image forming apparatus 1 operating in the second operation mode in addition to the operations of the image forming apparatus 1 performed by the processes of ACT310, ACT320, ACT330, ACT340, and ACT350 shown in Fig. 5. After performing the process of ACT380, the control unit 100 ends the process of the flowchart shown in Fig. 5.

[0097] In the flowchart shown in Fig. 5, some of the processes of ACT310, ACT320, ACT330, ACT340, ACT350, ACT370, and ACT380 may be omitted. In the eleventh operation, some of the processes of ACT310, ACT320, ACT330, ACT340, ACT350, and ACT370 may be omitted. In the twelfth operation, some of the processes of ACT310, ACT320, ACT330, ACT340, ACT350, and ACT380 may be omitted.

[0098] 5, some or all of the processes among ACT310, ACT320, ACT330, ACT340, ACT350, and ACT360 may be performed in a different order or in parallel, with the exception that the processes of ACT370 and ACT380 are performed after ACT360.

[0099] (Second abnormality processing) The second abnormality process will be described. FIG. 6 is a diagram showing an example of the flow of the second abnormality process performed by the control unit 100 in ACT220 shown in FIG. 4. ACT310, ACT320, ACT330, and ACT360 shown in FIG. 6 are similar to ACT310, ACT320, ACT330, and ACT360 shown in FIG. 5, and therefore the description will be omitted. The operation of the image forming apparatus 1 performed by the respective processes of ACT310, ACT320, ACT330, ACT410, ACT420, and ACT430 shown in FIG. 6 is an example of the 21st operation. The operation of the image forming apparatus 1 performed by the respective processes of ACT310, ACT320, ACT330, ACT410, ACT420, and ACT440 shown in FIG. 6 is an example of the 22nd operation. That is, the operations of the image forming apparatus 1 performed by the processes of ACT310, ACT320, ACT330, ACT410, and ACT420 shown in FIG. 6 are common to both the 21st operation and the 22nd operation.

[0100] In the flow chart shown in FIG. 6, after performing the process of ACT330, the control unit 100 transmits the second abnormality notification information (ACT410). The second abnormality notification information is, for example, information including lubricant depletion information. The second abnormality notification information may be information including information indicating that the motor signal value is out of the second range instead of or in addition to the lubricant depletion information. The second abnormality notification information may be configured to include other information in addition to either one or both of these two pieces of information. The destination to which the control unit 100 transmits the second abnormality notification information in ACT410 is an information processing device or the like communicably connected to the image forming apparatus 1. The information processing device is, for example, a PC of a company that performs maintenance of the image forming apparatus 1, an information processing terminal of an administrator that manages the image forming apparatus 1, or the like, but is not limited thereto. The second abnormality notification information is an example of the notification information described above.

[0101] Next, the control unit 100 displays the second abnormality notification information (ACT420). In ACT420, the control unit 100 displays the second abnormality notification information on a display unit of the control panel 12, a display unit of an information processing device communicably connected to the image forming apparatus 1, etc. The information processing device is, for example, a PC in a company that performs maintenance on the image forming apparatus 1, an information processing terminal of an administrator that manages the image forming apparatus 1, etc., but is not limited to these.

[0102] In ACT360 shown in Fig. 6, when the control unit 100 determines that the current operation mode of the image forming apparatus 1 is the first operation mode, it performs a third additional operation (ACT430). The third additional operation may be any operation that can be additionally performed by the image forming apparatus 1 operating in the first operation mode in addition to the operations of the image forming apparatus 1 performed by the processes of ACT310, ACT320, ACT330, ACT410, and ACT420 shown in Fig. 6. After performing the process of ACT430, the control unit 100 ends the process of the flowchart shown in Fig. 6.

[0103] On the other hand, in ACT360 shown in Fig. 6, when the control unit 100 determines that the current operation mode of the image forming apparatus 1 is the second operation mode, it performs a fourth additional operation (ACT440). The fourth additional operation may be any operation that can be additionally performed by the image forming apparatus 1 operating in the second operation mode in addition to the operations of the image forming apparatus 1 performed by the processes of ACT310, ACT320, ACT330, ACT410, and ACT420 shown in Fig. 6. After performing the process of ACT440, the control unit 100 ends the process of the flowchart shown in Fig. 6.

[0104] In the flowchart shown in FIG. 6, some of the processes in ACT310, ACT320, ACT330, ACT410, ACT420, ACT430, and ACT440 may be omitted. In the twenty-first operation, some of the processes in ACT310, ACT320, ACT330, ACT410, ACT420, and ACT430 may be omitted. In the twenty-second operation, some of the processes in ACT310, ACT320, ACT330, ACT410, ACT420, and ACT440 may be omitted.

[0105] In the flowchart shown in Fig. 6, some or all of the processes among ACT310, ACT320, ACT330, ACT410, ACT420, and ACT360 may be performed in a different order or in parallel, but the processes of ACT430 and ACT440 are performed after ACT360.

[0106] As described above, the image forming apparatus 1 according to the embodiment performs a first operation when the motor signal value falls outside the first range while driving the motor MT in the first operation mode, and performs a second operation when the motor signal value falls outside the second range while driving the motor MT in the second operation mode. This allows the image forming apparatus 1 to perform an operation according to a malfunction occurring in the fixing device AD ​​at a desired timing.

[0107] (First Modification of the Embodiment) A first modification of the embodiment will be described. In the first modification of the embodiment, the control unit 100 sets a threshold value THCA instead of the threshold value THAA, sets a threshold value THCB instead of the threshold value THAB, sets a threshold value THDA instead of the threshold value THBA, and sets a threshold value THDB instead of the threshold value THBB. The threshold value THCA is a value smaller than the threshold value THAA by a predetermined percentage. For example, the threshold value THCA is a value smaller than the threshold value THAA by 10% of the threshold value THAA. The threshold value THCB is a value larger than the threshold value THAB by a predetermined percentage. For example, the threshold value THCB is a value larger than the threshold value THAB by 10% of the threshold value THAB. That is, the first range according to the first modification of the embodiment is a range narrower than the first range according to the embodiment, and is a range included inside the first range according to the embodiment. For example, the threshold value THDA is a value smaller than the threshold value THBA by 10% of the threshold value THBA. The threshold value THDB is a value larger than the threshold value THBB by a predetermined percentage. For example, the threshold value THDB is a value that is 10% greater than the threshold value THBB. That is, the second range according to the first modification of the embodiment is a range that is narrower than the second range according to the embodiment, and is a range that is included inside the second range according to the embodiment.

[0108] In the first modification of the embodiment, the first abnormality notification information includes, for example, information indicating that there is a high possibility that a contact failure occurs between the fixing member ADA and the pressing member ADB in the fixing device AD ​​driven by the motor MT, information indicating that the motor signal value is out of the first range, and the like. The first abnormality notification information may include other information in addition to either or both of these two pieces of information. In the first modification of the embodiment, the processes ACT310, ACT320, and ACT330 are omitted from the first abnormality processing. In the first modification of the embodiment, the second abnormality notification information includes information indicating that there is a high possibility that the lubricant in the fixing member ADA is depleted in the fixing device AD ​​driven by the motor MT, information indicating that the motor signal value is out of the first range, and the like. The second abnormality notification information may include other information in addition to either or both of these two pieces of information. In the first modification of the embodiment, the processes ACT310, ACT320, and ACT330 are omitted from the second abnormality processing. As a result, the image forming apparatus 1 can perform operations such as notifying that there is a high possibility of a malfunction occurring in the fixing device AD ​​or displaying that there is a high possibility of a malfunction occurring in the fixing device AD ​​before a malfunction occurs in the fixing device AD ​​through the first or second operation.

[0109] (Modification 2 of the embodiment) A second modification of the embodiment will be described. In the second modification of the embodiment, the control unit 100 may be configured to perform the determination processes of ACT170 and ACT200 shown in Fig. 4 using a machine learning model. In this case, the threshold value set in ACT140 shown in Fig. 4 may be incorporated into the machine learning model.

[0110] (Modification 3 of the embodiment) A third modification of the embodiment will be described. In the third modification of the embodiment, the control unit 100 may perform the determination processes of ACT170 and ACT200 shown in FIG. 4 based on a detection difference value instead of based on a motor signal value. The detection difference value is a difference value between a motor signal value and a reference value that is a predetermined reference. When the process of ACT170 is performed based on the detection difference value and the operation mode of the image forming apparatus 1 is the first operation mode, the control unit 100 determines whether or not the detection difference value is smaller than the difference value between the threshold value THAB and the reference value in ACT170. When the process of ACT200 is performed based on the detection difference value and the operation mode of the image forming apparatus 1 is the first operation mode, the control unit 100 determines whether or not the detection difference value is larger than the difference value between the threshold value THAA and the reference value in ACT200. When the process of ACT170 is performed based on the detection difference value and when the operation mode of the image forming apparatus 1 is the second operation mode, the control unit 100 determines whether or not the detection difference value is smaller than the difference value between the threshold value THBB and the reference value in ACT170. When the process of ACT170 is performed based on the detection difference value and when the operation mode of the image forming apparatus 1 is the second operation mode, the control unit 100 determines whether or not the detection difference value is larger than the difference value between the threshold value THBA and the reference value in ACT200.

[0111] As a result, even if the correspondence between the drive current value and the motor signal value varies for each of multiple image forming devices 1 due to individual differences in the motors MT, each image forming device 1 can accurately perform operations in response to malfunctions occurring in the fixing device AD ​​at the desired timing.

[0112] (Fourth Modification of the Embodiment) A fourth modified example of the embodiment will now be described. In the fourth modified example of the embodiment, the difference between the first operation mode and the second operation mode is not the rotation speed of the motor MT but the magnitude of the pressing force.

[0113] The first operation mode in the fourth modified embodiment is an operation mode in which, when the pressing member ADB is pressed against the fixing member ADA by the biasing member, the motor MT is driven while pressing the pressing member ADB against the fixing member ADA with a pressing force of a first magnitude. In other words, the first operation mode is an operation mode in which the motor MT is driven while the pressing member ADB and the fixing member ADA are in contact with each other with a pressing force of a first magnitude. For example, when forming an image on A4-sized plain paper, the image forming apparatus 1 performs an operation of forming an image on the plain paper in the first operation mode. The pressing force of the first magnitude is, for example, 400 N. The pressing force of the first magnitude may be a force smaller than 400 N or a force larger than 400 N.

[0114] The second operation mode in the fourth modified embodiment is an operation mode in which, when the pressing member ADB is pressed against the fixing member ADA by the biasing member, the motor MT is driven while pressing the pressing member ADB against the fixing member ADA with a pressing force of a second magnitude. In other words, the second operation mode is an operation mode in which the motor MT is driven while the pressing member ADB and the fixing member ADA are in contact with each other with a pressing force of a second magnitude. For example, when forming an image on A4-sized cardboard, the image forming apparatus 1 performs an operation of forming an image on the cardboard in the second operation mode. The pressing force of the second magnitude is, for example, 100 N. The pressing force of the second magnitude may be a force smaller than 100 N or a force larger than 100 N.

[0115] 7 is a diagram showing an example of a second correspondence relationship between a drive current value and a motor signal value in the fourth modification of the embodiment.

[0116] 7, the horizontal axis represents the drive current value. The drive current value changes depending on the load of the motor MT. The vertical axis represents the motor signal value. The solid line plotted on the graph represents the second correspondence relationship when the image forming apparatus 1 operates in the first operation mode and the second operation mode.

[0117] For example, when the operation mode of the image forming apparatus 1 is the first operation mode and the fixing device AD ​​driven by the motor MT is operating normally, the drive current value indicates a value within the normal range from the value DAA to the value DAB shown in Fig. 7. For example, when the operation mode of the image forming apparatus 1 is the first operation mode and a contact failure occurs between the fixing member ADA and the pressing member ADB in the fixing device AD ​​driven by the motor MT, the drive current value indicates a value smaller than the value DAB shown in Fig. 7. For example, when the operation mode of the image forming apparatus 1 is the first operation mode and a lubricant depletion occurs in the fixing member ADA in the fixing device AD ​​driven by the motor MT, the drive current value indicates a value larger than the value DAA shown in Fig. 7.

[0118] For example, when the operation mode of the image forming apparatus 1 is the second operation mode and the fixing device AD ​​driven by the motor MT is operating normally, the drive current value indicates a value within the normal range from value DBA to value DBB shown in Fig. 7. For example, when the operation mode of the image forming apparatus 1 is the second operation mode and a contact failure occurs between the fixing member ADA and the pressing member ADB in the fixing device AD ​​driven by the motor MT, the drive current value indicates a value smaller than value DBB shown in Fig. 7. For example, when the operation mode of the image forming apparatus 1 is the second operation mode and a lubricant depletion occurs in the fixing member ADA in the fixing device AD ​​driven by the motor MT, the drive current value indicates a value larger than value DBA shown in Fig. 7.

[0119] The threshold value THCA shown in FIG. 7 indicates the motor signal value when the drive current value is the value DAA. The threshold value THCB shown in FIG. 7 indicates the motor signal value when the drive current value is the value DAB. The threshold value THDA shown in FIG. 7 indicates the motor signal value when the drive current value is the value DBA. The threshold value THDB shown in FIG. 7 indicates the motor signal value when the drive current value is the value DBB. For convenience of explanation, the range from the threshold value THCA to the threshold value THCB will be referred to as the third range. The third range is a modified example of the first range in the embodiment. For convenience of explanation, the range from the threshold value THDA to the threshold value THDB will be referred to as the fourth range. The fourth range is a modified example of the second range in the embodiment.

[0120] The fourth range is a range in which at least one of the upper limit value and the lower limit value is different from the third range. In the example shown in FIG. 7, the fourth range is different from the third range in both the upper limit value and the lower limit value. Therefore, when the operation mode of the image forming apparatus 1 is the first operation mode, the control unit 100 can determine whether or not the motor signal value is outside the third range by using the thresholds THCA and THCB. When the operation mode of the image forming apparatus 1 is the second operation mode, the control unit 100 can determine whether or not the motor signal value is outside the fourth range by using the thresholds THDA and THDB.

[0121] FIG. 8 is a diagram showing an example of a flow of a process for performing a first operation or a second operation among the processes performed by the image forming apparatus 1 according to the fourth modification of the embodiment.

[0122] The control unit 100 waits until the printing operation starts (ACT510). For example, when the control unit 100 receives a print job, it determines to start the printing operation. In this case, the print job includes information indicating the type of print medium on which an image is to be formed. In the embodiment, the printing operation is an operation performed by the image forming apparatus 1, including transporting the print medium and forming an image on the print medium. In the flowchart shown in FIG. 8, the flow of the process of performing the printing operation among the processes performed by the image forming apparatus 1 is omitted.

[0123] When the control unit 100 determines to start a printing operation (ACT510-YES), it sets a threshold value (ACT520). More specifically, in ACT520, the control unit 100 identifies the type of print medium on which an image is to be formed based on the print job received in ACT510. The control unit 100 switches the operation mode according to the identified type. For example, in ACT520, when the identified type is A4 size plain paper, the control unit 100 sets the operation mode of the image forming device 1 to a first operation mode. For example, in ACT520, when the identified type is A4 print paper, the control unit 100 sets the operation mode of the image forming device 1 to a second operation mode. After setting the operation mode to either the first operation mode or the second operation mode, the control unit 100 sets a threshold value according to the current operation mode of the image forming device 1 as a threshold value for the motor signal value. For example, when the current operation mode of the image forming apparatus 1 is the first operation mode, the control unit 100 sets the threshold value THCA, which is the upper limit of the first range, and the threshold value THCB, which is the lower limit of the first range, as the threshold value for the motor signal value. This allows the control unit 100 to determine whether the motor signal value has deviated from the third range, which is the range from the threshold value THCA to the threshold value THCB. For example, when the current operation mode of the image forming apparatus 1 is the second operation mode, the control unit 100 sets the threshold value THDA, which is the upper limit of the fourth range, and the threshold value THDB, which is the lower limit of the fourth range, as the threshold value for the motor signal value. This allows the control unit 100 to determine whether the motor signal value has deviated from the fourth range, which is the range from the threshold value THDA to the threshold value THDB.

[0124] Next, the control unit 100 starts the printing operation and also starts the contact operation (ACT530). At this time, the control unit 100 controls the pressing force adjustment mechanism ADC to start contacting the pressing member ADB with the outer peripheral surface of the fixing member ADA with a pressing force according to the current operation mode of the image forming apparatus 1.

[0125] Next, the control unit 100 waits until the contact operation started in ACT 530 is completed (ACT 540). The process of ACT 540 is similar to the process of ACT 130 shown in FIG. 4, and therefore a detailed description thereof will be omitted.

[0126] When the control unit 100 determines that the contact operation started in ACT540 is completed (ACT540-YES), the control unit 100 drives the motor MT at a predetermined rotation speed to start rotating the pressing member ADB (ACT550). In other words, the control unit 100 starts driving the fixing device AD ​​in ACT550. For example, the control unit 100 drives the motor MT at 1500 rpm in ACT550.

[0127] Next, the control unit 100 controls the heater of the heating unit HT to start heating the fixing member ADA (ACT560).

[0128] Next, the control unit 100 acquires the motor signal, and determines whether the motor signal value of the acquired motor signal is smaller than the lower limit value set in ACT 520 (ACT 570). The lower limit value is the smaller threshold value among the threshold values ​​set by the control unit 100 in ACT 520.

[0129] When the control unit 100 determines that the motor signal value of the acquired motor signal is smaller than the lower limit value set in ACT520 (ACT570-YES), it stores contact failure information in the storage device 1102 (ACT580).

[0130] Next, the control unit 100 performs the third abnormality processing (ACT590). The third abnormality processing is processing in which the 31st operation or the 32nd operation is performed as an operation corresponding to the current operation mode of the image forming apparatus 1. The 31st operation is the first operation performed in the third abnormality processing by the image forming apparatus 1 operating in the first operation mode. That is, the 31st operation is a modified example of the 11th operation according to the embodiment. The 32nd operation is the second operation performed in the third abnormality processing by the image forming apparatus 1 operating in the second operation mode. That is, the 32nd operation is a modified example of the 12th operation according to the embodiment. The flow of the processing in which the image forming apparatus 1 performs the third abnormality processing is similar to the flow of the first abnormality processing, so a detailed description will be omitted. However, in the third abnormality processing, the third abnormality notification information is used instead of the first abnormality notification information in ACT340 and ACT350. The third abnormality notification information is, for example, information including contact failure information. The third abnormality notification information may be information including information indicating that the motor signal value is out of the third range, instead of or in addition to the contact failure information. The third abnormality notification information may be configured to include other information in addition to either or both of these two pieces of information. After performing the third abnormality process, the control unit 100 ends the process of the flowchart shown in FIG. 8.

[0131] On the other hand, when the control unit 100 determines that the motor signal value of the acquired motor signal is equal to or greater than the lower limit value set in ACT520 (ACT570-NO), the control unit 100 determines whether or not the motor signal value of the acquired motor signal is greater than the upper limit value set in ACT520 (ACT600). The upper limit value is the larger of the threshold values ​​set by the control unit 100 in ACT520.

[0132] When the control unit 100 determines that the motor signal value of the acquired motor signal is greater than the upper limit value set in ACT520 (ACT600-YES), it stores lubricant depletion information in the storage device 1102 (ACT610).

[0133] Next, the control unit 100 performs the fourth abnormality processing (ACT620). The fourth abnormality processing is a processing to perform the 41st operation or the 42nd operation as an operation corresponding to the current operation mode of the image forming apparatus 1. The 41st operation is a first operation performed in the fourth abnormality processing by the image forming apparatus 1 operating in the first operation mode. That is, the 41st operation is a modified example of the 21st operation according to the embodiment. The 42nd operation is a second operation performed in the fourth abnormality processing by the image forming apparatus 1 operating in the second operation mode. That is, the 42nd operation is a modified example of the 22nd operation according to the embodiment. The flow of the processing in which the image forming apparatus 1 performs the fourth abnormality processing is similar to the flow of the second abnormality processing, and therefore a detailed description thereof will be omitted. However, in the fourth abnormality processing, the fourth abnormality notification information is used in ACT340 and ACT350 instead of the second abnormality notification information. The fourth abnormality notification information is, for example, information including lubricant depletion information. The fourth abnormality notification information may include information indicating that the motor signal value is out of the fourth range instead of or in addition to the lubricant depletion information. The fourth abnormality notification information may include other information in addition to either or both of these two pieces of information. After performing the fourth abnormality process, the control unit 100 ends the process of the flowchart shown in FIG. 8.

[0134] On the other hand, when the control unit 100 determines that the motor signal value of the acquired motor signal is equal to or less than the upper limit value set in ACT520 (ACT600-NO), it determines whether the printing operation started in ACT530 has ended (ACT630). The process of ACT630 is the same as the process of ACT230 shown in FIG. 4, and therefore a detailed description thereof will be omitted.

[0135] If the control unit 100 determines that the printing operation started in ACT530 has not finished (ACT630-NO), it transitions to ACT570, acquires a motor signal, and again determines whether the motor signal value of the acquired motor signal is smaller than the lower limit value set in ACT520.

[0136] On the other hand, if the control unit 100 determines that the printing operation started in ACT530 has ended (ACT630-YES), it ends the process of the flowchart shown in FIG.

[0137] As described above, the image forming apparatus 1 according to the fourth modified embodiment performs the first operation when the motor signal value falls outside the third range while the motor MT is being driven in the first operation mode, and performs the second operation when the motor signal value falls outside the fourth range while the motor MT is being driven in the second operation mode. This allows the image forming apparatus 1 to perform an operation in response to a malfunction occurring in the fixing device AD ​​at a desired timing.

[0138] (Other variations) In the embodiments or variants of the embodiments described above, the difference between the first operating mode and the second operating mode may be the nip pressure of the nip formed by the fixing member ADA and the pressing member ADB in the fixing device AD.

[0139] In the above-described embodiment or each modified example of the embodiment, the difference between the first operation mode and the second operation mode may be the nip pressure of the nip formed by the fixing member ADA and the pressing member ADB in the fixing device AD, because the load on the motor MT also changes depending on the difference in the nip pressure.

[0140] In the above-described embodiment or each modified example of the embodiment, the difference between the first operation mode and the second operation mode may be the target temperature of heating the fixing member ADA by the heating unit HT, because the viscosity of the lubricant changes with the change in temperature of the fixing member ADA, and as a result, the load of the motor MT changes.

[0141] The above-described embodiments and the modified examples of the embodiments may be combined in any manner.

[0142] As described above, the image forming apparatus (image forming apparatus 1 in the example described above) has a conveying section (secondary transfer roller 23, two registration rollers 24, fixing device AD, various rollers in double-sided printing device DF, etc. in the example described above), an image forming section (image forming unit 114 in the example described above), a fixing device (fixing device AD ​​in the example described above), a motor (motor MT in the example described above), and a control section (control section 100 in the example described above). The conveying section conveys the print medium. The image forming section forms a toner image of a target image on the print medium conveyed by the conveying section. The fixing device heats the print medium after the toner image is formed by the image forming section, and fixes the toner image to the print medium as a target image. The motor drives the fixing device, and outputs a signal (motor signal in the example described above) of a magnitude (motor signal value in the example described above) corresponding to the value of the drive current (drive current value in the example described above). The control unit performs a first operation when the magnitude of the signal deviates from a first range (the first range or the third range in the above-described example) while driving the motor in the first operation mode, and performs a second operation when the magnitude of the signal deviates from a second range (the second range or the fourth range in the above-described example) different from the first range while driving the motor in the second operation mode. This allows the image forming apparatus to perform an operation according to a malfunction occurring in the fixing device at a desired timing.

[0143] In the image forming apparatus, a configuration may be used in which at least one of the upper limit value and the lower limit value of the second range is different from that of the first range.

[0144] In the image forming apparatus, a configuration may be used in which the first operating mode is an operating mode in which the motor is driven at a first rotation speed (1500 rpm in the example described above), and the second operating mode is an operating mode in which the motor is driven at a second rotation speed different from the first rotation speed (940 rpm in the example described above).

[0145] In the image forming apparatus, the fixing device may include a heating section (heating section HT in the example described above), a fixing member heated by the heating section (fixing member ADA in the example described above), and a pressing member (pressing member ADB in the example described above) that forms a nip with the fixing member by contacting the fixing member, and a configuration in which a first operating mode is an operating mode in which the motor is driven while the pressing member and the fixing member are in contact with a first force (a pressing force of a first magnitude, i.e., 400 N in the example described above), and a second operating mode is an operating mode in which the motor M is driven while the pressing member and the fixing member are in contact with a second force different from the first force (a pressing force of a second magnitude, i.e., 100 N in the example described above).

[0146] In the image forming apparatus, a configuration may be used in which the first operation and the second operation include an operation of outputting notification information (in the example described above, each of the first to fourth abnormality notification information) including information indicating that a malfunction has occurred in the fixing device (in the example described above, contact failure information and lubricant depletion information) to an information processing device.

[0147] In the image forming apparatus, a configuration may be used in which the first operation includes an operation related to the magnitude of a signal output from a motor being outside a first range, and the second operation includes an operation related to the magnitude of the signal being outside a second range.

[0148] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention.

[0149] A program for implementing the functions of any of the components in the device described above (for example, image forming device 1) may be recorded on a computer-readable recording medium, and the program may be read into a computer system and executed. The term "computer system" as used herein includes hardware such as an operating system (OS) and peripheral devices. The term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and compact disk (CD)-ROMs, as well as storage devices such as hard disks built into computer systems. The term "computer-readable recording medium" also includes those that hold a program for a certain period of time, such as volatile memory (RAM) inside a computer system that serves as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line.

[0150] The above program may be transmitted from a computer system in which the program is stored in a storage device or the like to another computer system via a transmission medium, or by transmission waves in the transmission medium. A "transmission medium" that transmits a program refers to a medium that has the function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The above program may be for realizing some of the above functions. The above program may be a so-called differential file (differential program) that can realize the above functions in combination with a program already recorded in the computer system. [Explanation of symbols]

[0151] 1...image forming apparatus, 11...printer section, 12...control panel, 20...intermediate transfer belt, 21...driven roller, 22...backup roller, 23...secondary transfer roller, 24...registration roller, 25...paper feed roller, 31, 32, 33, 34...image forming station, 40...belt cleaner, 41...first detection section, 42...second detection section, 43...third detection section, 100...control section, 111, 112...paper feed cassette, 114...image forming unit, 311...photosensitive drum, 312 ...electric charger, 313...exposure scanning head, 314...developing device, 315...photoconductor cleaner, 316...primary transfer roller, 1101...arithmetic unit, 1102...storage device, 1103...data receiving unit, 1104...image data development unit, AD...fixing device, ADA...fixing member, ADB...pressure member, ADC...pressure adjustment mechanism, DF...duplex printing device, HT...heating unit, LA, LB, LC...transport path, MT...motor, PA...junction, PB...branching unit, TA...manual feed tray, TB...paper output tray

Claims

1. An image forming apparatus for forming a target image on a print medium using toner, an image forming unit that forms a toner image of a target image on the print medium; a motor that drives the image forming unit and outputs a signal having a magnitude corresponding to a value of a drive current; A control unit; Equipped with The control unit is Controlling the motor in either a first operating mode or a second operating mode; when the operation mode for driving the motor is the first operation mode, an upper limit value and a lower limit value of a first range are set as threshold values ​​for the magnitude of the signal; When the operation mode is the second operation mode, an upper limit value and a lower limit value of a second range different from the first range are set as the threshold values; performing a first operation when the magnitude of the signal falls outside the first range while the motor is being driven in the first operation mode; performing a second operation when the magnitude of the signal falls outside the second range while driving the motor in the second operation mode; the first operating mode is an operating mode in which the motor is driven at a first rotation speed; the second operating mode being an operating mode in which the motor is driven at a second rotational speed; Image forming device.

2. The second range is a range in which at least one of an upper limit value and a lower limit value is different from that of the first range. The image forming apparatus according to claim 1 .

3. The image forming unit includes: A heating unit; a fixing member heated by the heating section; a pressing member that contacts the fixing member to form a nip with the fixing member; Equipped with the first operation mode is an operation mode in which the motor is driven while the pressing member and the fixing member are in contact with each other with a first force, the second operation mode is an operation mode in which the motor is driven while the pressing member and the fixing member are in contact with each other with a second force different from the first force; The image forming apparatus according to claim 1 .

4. A device that is communicatively connected to an information processing device; The first operation and the second operation include an operation of outputting, to the information processing device, notification information including information indicating that a malfunction has occurred in the image forming device. The image forming apparatus according to claim 1 .

5. a conveying unit that conveys two or more types of the print medium; the control unit drives the motor in one of the first and second operation modes, the operation mode corresponding to the type of the print medium. The image forming apparatus according to claim 1 .

Images