Image-forming device

Abstract

To precisely determine presence or absence of wrapping of a recording medium around a heating roll as compared with a configuration for determining presence or absence of wrapping of a recording medium around a heating roll on the basis of a temperature drop gradient when clogging of the recording medium occurs in a fixing section.SOLUTION: An image-forming device includes: a fixing section that has a heating roll and a pressurizing roll and fixes an image to a recording medium; detection means for detecting temperature of the fixing section; cooling means for cooling the fixing section; and a processor for controlling the fixing section and the cooling means on the basis of temperature information acquired from the detection means. The processor increases cooling capacity of the cooling means when clogging of the recording medium occurs in the fixing section and the recording medium may wrap around the heating roll, increases temperature of the fixing section when the fixing section reaches a predetermined temperature or less, and determines presence or absence of wrapping of the recording medium from a temperature increase gradient based on the temperature information.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to an image forming apparatus. [Background technology]

[0002] Patent document 1 discloses an image forming apparatus comprising a fixing unit that uses heat to fix a developer image adhered to a recording medium onto the recording medium, a heat source that supplies heat to the fixing unit, a fixing temperature detection unit that detects the temperature of the fixing unit heated by the heat source, a timing unit that measures elapsed time, a temperature gradient calculation unit that calculates a temperature gradient value of the temperature change of the fixing unit based on the detection result of the temperature of the fixing unit by the fixing temperature detection unit, and a remainder determination unit that determines whether the recording medium remains in the fixing unit based on the temperature gradient value calculated by the temperature gradient calculation unit and the elapsed time of the temperature gradient value measured by the timing unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 62-254159 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure aims to accurately determine whether or not a recording medium is wrapped around a heating roll when a recording medium becomes clogged in a fixing section, compared to a configuration that determines whether or not a recording medium is wrapped around a heating roll based on a temperature drop gradient. [Means for solving the problem]

[0005] The image forming apparatus of the first aspect of the present disclosure has a heating roll that heats a recording medium, and a pressure roll that pressurizes the recording medium together with the heating roll, and is equipped with a fixing unit that fixes an image onto the recording medium, a detection means that detects the temperature of the fixing unit, a cooling means that cools the fixing unit, and a processor that controls the fixing unit and the cooling means based on temperature information acquired from the detection means, and when a jam of the recording medium occurs in the fixing unit and there is a possibility that the recording medium will wrap around the heating roll, the processor increases the cooling capacity of the cooling means, and when the fixing unit reaches a predetermined temperature or lower, increases the temperature of the fixing unit and determines whether or not the recording medium has wrapped around the heating roll from the temperature rise gradient based on the temperature information.

[0006] An image forming apparatus of a second aspect of the present disclosure is the image forming apparatus of the first aspect, wherein the processor determines that the recording medium is wrapped around the heating roll when the temperature rise gradient value is below a predetermined threshold value.

[0007] An image forming apparatus of a third aspect of the present disclosure is the image forming apparatus of the first aspect, wherein when a jam of the recording medium occurs in the fixing section, the processor stops heating the heating roll and determines whether or not there is a possibility of the recording medium wrapping around the recording medium from a temperature drop gradient based on the temperature information.

[0008] An image forming apparatus of a fourth aspect of the present disclosure is the image forming apparatus of the third aspect, wherein the processor determines that there is a possibility that the recording medium will wrap around the heating roll when the temperature drop gradient value is below a predetermined threshold value.

[0009] An image forming apparatus of a fifth aspect of the present disclosure is the image forming apparatus of the fourth aspect, wherein the processor changes the predetermined threshold value based on at least one of the size of the recording medium and the thickness of the recording medium.

[0010] An image forming apparatus of a sixth aspect of the present disclosure is the image forming apparatus of the first aspect, wherein when the fixing unit reaches a predetermined temperature or lower, the processor increases the temperature of the fixing unit, determines whether or not the recording medium is wrapped around the recording medium from a temperature rise gradient based on the temperature information, and if it determines that the recording medium is not wrapped around the recording medium, maintains the temperature of the fixing unit at a temperature or higher at which an image can be fixed to the recording medium.

[0011] An image forming apparatus according to a seventh aspect of the present disclosure is the image forming apparatus according to the first aspect, wherein the cooling unit is a cooling fan that blows air to the fixing unit, and the processor controls the rotation speed of the cooling fan.

[0012] An image forming apparatus according to an eighth aspect of the present disclosure is the image forming apparatus according to the seventh aspect, wherein the cooling fans are disposed upstream and downstream of the fixing unit in a transport direction of the recording medium.

[0013] An image forming apparatus of a ninth aspect of the present disclosure is an image forming apparatus of any one of the first to eighth aspects, wherein the processor, when a jam of the recording medium occurs in the fixing section, stops heating the heating roll, and when the fixing section reaches a predetermined temperature or below, reheats the heating roll, and measures the time from when the fixing section reaches a predetermined temperature or below to when the heating roll is reheated, and determines that the recording medium has wrapped around the recording medium if the measured time exceeds a predetermined winding time. Effect of the Invention

[0014] In the image forming apparatus of the first embodiment, when a recording medium becomes clogged in the fixing section, it is possible to more accurately determine whether or not the recording medium is wrapped around the heating roll, compared to a method in which the determination of whether or not the recording medium is wrapped around the heating roll is based on a temperature drop gradient.

[0015] In the image forming apparatus of the second embodiment, when a recording medium becomes clogged in the fixing section, it is possible to accurately determine whether or not the recording medium is wrapped around the heating roll, compared to an apparatus that determines that the recording medium is not wrapped around the heating roll when the temperature rise gradient value is below a predetermined threshold value.

[0016] In the image forming apparatus of the third embodiment, when a recording medium becomes clogged in the fixing section, it is possible to more accurately determine whether or not the recording medium is wrapped around the heating roll, compared to a case where the determination is made based solely on the temperature rise gradient.

[0017] In the image forming apparatus of the fourth embodiment, when a recording medium becomes clogged in the fixing section, it is possible to accurately determine whether or not the recording medium has wrapped around the heating roll, compared to an apparatus that determines that there is no possibility of the recording medium wrapping around the heating roll when the temperature drop gradient value is below a predetermined threshold value.

[0018] In the image forming apparatus of the fifth aspect, it is possible to more accurately determine whether or not the recording medium is wrapped around the heating roll, compared to an apparatus that uses a constant gradient as a threshold value regardless of the size and thickness of the recording medium.

[0019] In the image forming apparatus of the sixth aspect, the recovery speed of the apparatus after a recording medium jam is cleared can be increased compared to an apparatus in which the temperature of the fixing section is lowered below the temperature at which an image can be fixed after it is determined that there is no wrapping of the recording medium.

[0020] In the image forming apparatus of the seventh aspect, the apparatus configuration can be simplified compared to an apparatus using a liquid-cooling type cooling means.

[0021] In the image forming apparatus of the eighth aspect, the cooling speed of the fixing unit can be increased compared to an image forming apparatus in which the cooling fans are disposed only on the upstream side or the downstream side of the fixing unit in the transport direction of the recording medium.

[0022] In the image forming apparatus of the ninth embodiment, it is possible to more accurately determine whether or not the recording medium is wrapped around the heating roll, compared to an apparatus that determines whether or not the recording medium is wrapped around the heating roll based only on the temperature rise gradient. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present disclosure. [Diagram 2] 2 is a diagram showing a heating roll and a pressure roll provided in a fixing unit of the image forming apparatus shown in FIG. 1, as viewed from the conveying direction of a recording medium. [Diagram 3] 2 is a block diagram showing a hardware configuration of a control device used in the image forming apparatus shown in FIG. 1. [Figure 4] 2 is a block diagram showing a functional configuration of the image forming apparatus shown in FIG. 1. [Diagram 5] 4 is a flowchart when a paper jam occurs in the image forming apparatus shown in FIG. [Figure 6] 6 is a flowchart of a first detection process shown in FIG. 5. [Figure 7] 2 is a flowchart showing a recovery process executed in the image forming apparatus shown in FIG. 1. [Figure 8] 8 is a flowchart of the second detection process shown in FIG. 7. [Figure 9] 6 is a control transition chart of components of the fixing unit when a paper jam occurs. [Figure 10] FIG. 11 is a diagram showing a determination of paper wrapping detection. [Figure 11] FIG. 11 is a diagram showing a determination of paper wrapping detection. [Figure 12] 13 is a chart showing transitions in detected temperature during target control in a normal state and in a paper-wrapped state. [Figure 13] 13 is a flowchart of another detection process for detecting paper wrapping. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An example of an image forming apparatus according to an embodiment of the present disclosure will be described.

[0025] An image forming apparatus 20 according to an embodiment of the present disclosure will be described below. Fig. 1 is a schematic diagram showing the configuration of the image forming apparatus 20 according to the present embodiment.

[0026] 1 is a device that forms an image on paper P as an example of a recording medium. Specifically, the image forming device 20 includes a paper feed section 30, a plurality of conveying sections 40, an image forming section 50, a fixing section 60, and a discharge section 80. Each section of the image forming device 20 will be described below.

[0027] (Paper feed section 30) The paper feed section 30 shown in FIG. 1 is a section in the image forming apparatus 20 that sends out paper P. This paper feed section 30 has a function of supplying (feeding) paper P to the image forming section 50. This paper feed section 30 has one or more paper feed trays 32 on which paper P is placed. The paper feed tray 32 is provided with a paper feed roller 34 that sends out the paper P placed at the top of the paper feed tray 32 one sheet at a time to the image forming section 50. The paper feed tray 32 is configured, for example, to be capable of storing a large volume of paper P and to store paper P of different types (paper types) and sizes. In this embodiment, the paper feed section 30 has four paper feed trays 32.

[0028] (Transport unit 40) 1 is a component that transports paper P in image forming apparatus 20. Specifically, a plurality of transport sections 40 are arranged at intervals on a transport path for paper P in image forming apparatus 20 (hereinafter, appropriately referred to as a "paper transport path"). These transport sections 40 have a function of transporting paper P sent out from paper supply section 30 along the paper transport path.

[0029] As shown in FIG. 1, each of the multiple transport sections 40 has a pair of transport rolls 42. The pair of transport rolls 42 rotate while sandwiching the paper P to transport the paper P along the transport path. Of the multiple transport sections 40, the one immediately before the image forming section 50, in other words, the one that is upstream of the image forming section 50 in the transport direction of the paper P and closest to the image forming section 50, is hereinafter referred to as a transport section 40R. The pair of transport rolls included in this transport section 40R is referred to as a pair of transport rolls 42R. The pair of transport rolls 42R is also referred to as a pair of registration rolls.

[0030] In this embodiment, the multiple transport sections 40 are configured to have a pair of transport rolls 42, but some or all of the transport sections 40 may be configured to have a transport belt instead of the pair of transport rolls 42, or some or all of the transport sections 40 may be configured to have a transport drum instead of the pair of transport rolls 42. In other words, the multiple transport sections 40 may use various transport members as long as they can transport the paper P along the paper transport path.

[0031] (Image forming unit 50) 1 is a component that forms an image on paper P sent out from paper feed unit 30 in image forming apparatus 20. Image forming unit 50 is an electrophotographic image forming unit that forms an image on paper P using toner.

[0032] The image forming unit 50 performs the steps of charging, exposing, developing, and transferring to form an image on the paper P. Note that the image forming unit 50 may also form an image on the paper P by performing the steps of charging, exposing, developing, and transferring to form an image on a transfer body, and then transferring the image from the transfer body to the paper P.

[0033] Furthermore, the image forming unit 50 may be configured to form an image on the paper P using a single color of toner (e.g., black toner), or may be configured to form an image on the paper P using multiple toners of different colors (e.g., black, yellow, magenta, and cyan toners).

[0034] (Fixing unit 60) The fixing section 60 shown in FIG. 1 is a component that fixes an image transferred to a sheet P to the sheet P in the image forming apparatus 20. As shown in FIG. 1, the fixing section 60 has a heating roll 62 that heats the sheet P and a pressure roll 64 that pressurizes the sheet P together with the heating roll 62. The fixing section 60 has a function of fixing the image transferred to the sheet P to the sheet P by heating and pressing the sheet P to which the image has been transferred with the heating roll 62 and the pressure roll 64. The heating roll 62 has a lamp 63 as a heat source therein. Specifically, three lamps 63 are arranged inside the heating roll 62. For example, halogen lamps may be used as these lamps 63. Note that in FIGS. 1 and 4, the three lamps 63 are shown as a first lamp 63A, a second lamp 63B, and a third lamp 63C, respectively. The heating roll 62 is configured to be rotatable by a rotational force from a drive motor 67 as a drive source. As the heating roll 62 rotates, the paper P sandwiched between the heating roll 62 and the pressure roll 64 is transported (sent out) in the paper transport direction.

[0035] 1, the fixing unit 60 has a housing 66. The heating roll 62 and the pressure roll 64 are each housed in the housing 66. The heating roll 62 and the pressure roll 64 are each rotatably supported by bearings provided in the housing 66. A drive motor 67 may be attached to the housing 66.

[0036] As shown in FIG. 2, the fixing section 60 has a temperature sensor 68 as an example of a detection unit for detecting the temperature of the fixing section 60. Specifically, the fixing section 60 has a plurality of temperature sensors 68 for measuring the surface temperature of the heating roll 62. In this embodiment, a total of three temperature sensors 68 are arranged so as to contact the surface of the heating roll 62, one at the center of the axial direction of the heating roll 62 and one at each of both axial end sides of the heating roll 62. In addition, in FIG. 2 and FIG. 4, the three temperature sensors 68 are respectively shown as a first temperature sensor 68A, a second temperature sensor 68B, and a third temperature sensor 68C. As shown in FIG. 2, the first temperature sensor 68A is a temperature sensor arranged at the center of the axial direction of the heating roll 62. In addition, the second temperature sensor 68B and the third temperature sensor 68C are temperature sensors arranged at both axial end sides of the heating roll 62.

[0037] In this embodiment, a contact-type temperature sensor that measures the temperature by contacting the surface of the heating roll 62 is used as the temperature sensor 68, but the present disclosure is not limited to this configuration, and a non-contact-type temperature sensor that measures the temperature without contacting the surface of the heating roll 62 may also be used.

[0038] 1, the fixing section 60 has a cooling device 70 as an example of a cooling means for cooling the fixing section 60. The cooling device 70 has a function of cooling the heating roll 62 by blowing air to the heating roll 62. Specifically, the cooling device 70 has an intake fan 72 and an exhaust fan 74 as an example of a pair of cooling fans that blow air to the heating roll 62.

[0039] The intake fan 72 is disposed upstream in the paper transport direction of the fixing unit 60. Specifically, the intake fan 72 is connected to an intake port 66A provided on the upstream side of the housing 66 in the paper transport direction.

[0040] The exhaust fan 74 is disposed downstream in the paper transport direction of the fixing unit 60. Specifically, it is connected to an exhaust port 66B provided on the downstream side of the housing 66 in the paper transport direction.

[0041] The air sucked into the housing 66 from the intake fan 72 removes heat from the heating roll 62 and is discharged to the outside of the housing 66 from the exhaust fan 74. This causes the heating roll 62 to cool.

[0042] In this embodiment, the intake fan 72 is connected to the intake port 66A of the housing 66, and the exhaust fan 74 is connected to the exhaust port 66B, but the present disclosure is not limited to this configuration. For example, the intake fan 72 may be connected only to the intake port 66A of the housing 66, and the exhaust fan 74 may not be connected to the exhaust port 66B. Even in this case, the air sucked into the housing 66 from the intake fan 72 is discharged from the exhaust port 66B after removing the heat from the heating roll 62. Also, for example, the intake fan 72 may not be connected to the intake port 66A of the housing 66, and the exhaust fan 74 may be connected only to the exhaust port 66B. Even in this case, the air in the housing 66 is discharged from the exhaust port 66B by the exhaust fan 74, so that the air is sucked into the housing 66 from the intake port 66A. As a result, the air sucked into the housing 66 is discharged from the exhaust port 66B by the exhaust fan 74 after removing the heat from the heating roll 62.

[0043] (Discharge section 80) 1 is a portion of the image forming apparatus 20 where paper P on which an image has been formed is discharged. Paper P on which an image has been formed by the image forming section 50 and on which the image has been fixed by the fixing section 60 is transported by the multiple transport sections 40 and discharged to the discharge section 80.

[0044] The image forming apparatus 20 also has a housing 22. The housing 22 houses a paper feed unit 30, a conveying unit 40, an image forming unit 50, and a fixing unit 60. The discharge unit 80 is disposed, for example, on the top or side of the housing 22. In this embodiment, the discharge unit 80 is disposed on the top of the housing 22.

[0045] The housing 22 also includes an opening / closing cover 24. The opening / closing cover 24 constitutes a part of the wall constituting the housing 22. By opening the opening / closing cover 24, for example, it becomes possible to replenish paper P to the paper feed tray 32 of the paper feed unit 30. By closing the opening / closing cover 24, the multiple paper feed trays 32 are covered from the outside by the opening / closing cover 24. Note that in this embodiment, a part of the front wall of the housing 22 is constituted by the opening / closing cover 24, but the present disclosure is not limited to this configuration. For example, a part of the right side wall, left side wall, or rear wall of the housing 22 may be constituted by the opening / closing cover. Also, each wall of the housing 22 may be constituted entirely by the opening / closing cover, or each wall may be constituted by multiple opening / closing covers.

[0046] The image forming apparatus 20 also includes a plurality of paper sensors 90 on the paper transport path. The paper sensors 90 are sensors that are turned on when the paper P passes (detection state) and turned off when the paper P does not pass (detection state). That is, the paper sensors 90 have a function of detecting the paper P.

[0047] In the image forming apparatus 20, as described above, a plurality of paper sensors 90 are arranged on the paper transport path. In this embodiment, as shown in FIG. 1, the paper sensor immediately before the transport section 40R, in other words, the paper sensor located upstream of the transport section 40R in the transport direction of the paper P and closest to the transport section 40R, is hereinafter referred to as the first paper sensor 90A. Also, the paper sensor immediately after the fixing section 60, in other words, the paper sensor located downstream of the fixing section 60 in the transport direction of the paper P and closest to the fixing section 60, is hereinafter referred to as the second paper sensor 90B. Furthermore, the paper sensor immediately before the discharge section 80, in other words, the paper sensor located upstream of the discharge section 80 in the transport direction of the paper P and closest to the discharge section 80, is hereinafter referred to as the third paper sensor 90C. Note that, in FIG. 1 and FIG. 4, only the first paper sensor 90A, the second paper sensor 90B, and the third paper sensor 90C are illustrated among the plurality of paper sensors 90, and the remaining paper sensors are omitted.

[0048] Next, an example of the hardware configuration of the image forming apparatus 20 of the present embodiment will be described.

[0049] 3, the image forming apparatus 20 has a CPU 101, a memory 102, a storage device 103 such as a hard disk drive, a communication interface (hereinafter referred to as "communication I / F") 104 for transmitting and receiving data to and from external devices via a network, a user interface (hereinafter referred to as "UI") device 105 including a touch panel or liquid crystal display and a keyboard, and a print engine 106. These components are connected to each other via a control bus 107.

[0050] The print engine 106 prints an image on paper P through processes such as charging, exposure, development, transfer, and fixing.

[0051] CPU 101 is a processor that executes a predetermined process based on a control program stored in memory 102 or storage device 103 to control the operation of image forming apparatus 20. Note that, in this embodiment, CPU 101 is described as reading and executing a control program stored in memory 102 or storage device 103, but it is also possible to store the program in a storage medium such as a CD-ROM and provide it to CPU 101. Note that CPU 101 in this embodiment is an example of a processor of the present disclosure.

[0052] FIG. 4 is a block diagram showing the functional configuration of the image forming apparatus 20 realized by executing the above control program.

[0053] 4, the image forming apparatus 20 of this embodiment has a temperature detection unit 110, a lamp control unit 112, a motor control unit 114, a fan control unit 116, a paper detection unit 118, a control management unit 120, a calculation unit 122, and a determination unit 124. Specifically, the temperature detection unit 110, the lamp control unit 112, the motor control unit 114, the fan control unit 116, the paper detection unit 118, the control management unit 120, the calculation unit 122, and the determination unit 124 are configured by the CPU 101.

[0054] The temperature detection unit 110 receives information transmitted from each temperature sensor 68. Specifically, the temperature detection unit 110 receives information from each of the first temperature sensor 68A, the second temperature sensor 68B, and the third temperature sensor 68C.

[0055] The lamp control unit 112 controls the output of each lamp 63. Specifically, the lamp control unit 112 controls the output of each of the first lamp 63A, the second lamp 63B, and the third lamp 63C. By controlling the output of each lamp 63, the heating of the paper P is controlled.

[0056] The motor control unit 114 controls the output of the drive motor 67. Specifically, the motor control unit 114 controls the output of the drive motor 67 to control the rotation speed of the heating roll 62.

[0057] The fan control unit 116 controls the output of the intake fan 72 and the exhaust fan 74. Specifically, the fan control unit 116 controls the rotation speed of the intake fan 72 and the rotation speed of the exhaust fan 74. By controlling the rotation speed of the intake fan 72 and the rotation speed of the exhaust fan 74, the speed of air flowing inside the housing 66 (wind speed) is controlled.

[0058] The paper detection unit 118 receives information from a plurality of paper sensors 90 .

[0059] The control management unit 120 controls the lamp control unit 112, the motor control unit 114, and the fan control unit 116. In other words, the control management unit 120 has a function of managing and controlling the state of the fixing unit 60. The control management unit 120 also manages information received by the paper detection unit 118. Specifically, the control management unit 120 temporarily stores and manages the information received by the paper detection unit 118. The information received by the paper detection unit 118 is temporarily stored in, for example, the memory 102 or the storage device 103.

[0060] The calculation unit 122 has a function of calculating necessary information from information received by the CPU 101, information stored in the memory 102 and the storage device 103, etc. The calculation unit 122 is used to obtain the temperature gradient of the heating roll 62, for example.

[0061] The determination unit 124 has a function of, for example, comparing a measured value or a calculated value with a threshold value to determine whether the measured value or the calculated value is large or small.

[0062] As described above, CPU 101 has a function of controlling fixing unit 60 and cooling device 70 based on temperature information obtained from each temperature sensor 63. Specifically, CPU 101 controls the rotation speed of intake fan 72 and exhaust fan 74.

[0063] When a jam of the paper P occurs in the fixing unit 60 and there is a possibility that the paper P will wrap around the heating roll 62, the CPU 101 increases the cooling capacity of the cooling device 70. Specifically, when there is a possibility that the paper P will wrap around the heating roll 62, the CPU 101 increases the rotation speed of each of the intake fan 72 and the exhaust fan 74. In other words, the CPU 101 increases the rotation speed of each of the intake fan 72 and the exhaust fan 74. Then, when the fixing unit 60 reaches a predetermined temperature (a predetermined temperature) or lower, the CPU 101 increases the temperature of the fixing unit 60 and determines whether or not the paper P has wrapped around the heating roll 62 from the temperature rise gradient based on the temperature information. Specifically, when the heating roll 62 reaches a predetermined temperature or lower, the CPU 101 increases the temperature of the heating roll 62 and determines whether or not the paper P has wrapped around the heating roll 62 from the temperature rise gradient based on the temperature information. Then, when the temperature rise gradient value is equal to or lower than a predetermined threshold value, the CPU 101 determines that the paper P has wrapped around the heating roll 62. Furthermore, when the CPU 101 determines that the sheet P is not wrapped around the heating roll 62, it causes the temperature of the fixing unit 60 to be maintained at a temperature at which an image can be fixed onto the sheet P or higher. In addition, the occurrence of a jam of the paper P in the fixing unit 60 mentioned here includes the occurrence of a jam of the paper P before or after the fixing unit 60.

[0064] Furthermore, when a jam of the paper P occurs in the fixing unit 60, the CPU 101 stops heating the heating roll 62 and determines whether or not there is a possibility of the paper P wrapping around the heating roll 62 from a temperature drop gradient based on the temperature information. Then, the CPU 101 determines that there is a possibility of the paper P wrapping around the heating roll 62 when the temperature drop gradient value is equal to or less than a predetermined threshold value (first detection threshold value).

[0065] Furthermore, the CPU 101 changes the predetermined threshold value based on at least one of the size and thickness of the paper P. Specifically, the CPU 101 changes the predetermined threshold value based on at least one of the size and thickness of the paper P, as shown in FIG.

[0066] Next, a flow when a paper jam occurs in the image forming apparatus 20 of this embodiment will be described with reference to Fig. 5. Note that Fig. 9 shows the operation of each part of the fixing unit 60.

[0067] 5, when a paper jam occurs, CPU 101 included in image forming apparatus 20 identifies the location of the paper jam on the paper transport path from the paper detection results of multiple paper sensors 90 arranged on the paper transport path (step S200). Specifically, CPU 101 identifies the location of the paper jam on the paper transport path based on detection information of paper P received from each paper sensor 90. The identified location of the paper jam is displayed, for example, on a display unit (not shown) such as a display included in image forming apparatus 20.

[0068] Next, CPU 101 determines whether the paper jam has occurred before or after fixing unit 60 (step S202). Specifically, when paper P has passed first paper sensor 90A but has not yet passed second paper sensor 90B, CPU 101 determines that the paper jam has occurred before or after fixing unit 60. If the paper jam has occurred before or after fixing unit 60, the process proceeds to step S204. On the other hand, if the paper jam has not occurred before or after fixing unit 60, image forming apparatus 20 enters a standby state until recovery operations, including clearing the paper jam, are performed.

[0069] Next, if the paper jam occurs before or after the fixing unit 60, the CPU 101 stops the drive motor 67 and each lamp 63 of the fixing unit 60 (step S204). Specifically, the CPU 101 stops the power supply to the drive motor 67 and each lamp 63.

[0070] Next, the CPU 101 executes a first detection process to detect wrapping of the paper P around the heating roll 62 (step S206). In the first detection process, it is determined whether or not there is a possibility that the paper P will wrap around the heating roll 62. The first detection process will be described in detail later.

[0071] When the execution of the first detection process is completed, the CPU 101 determines whether or not there is a possibility that the paper has wrapped around the heating roll 62 (step S208). Specifically, the CPU 101 determines whether or not there is a possibility that the paper has wrapped around the heating roll 62 from the result of the first detection process. If there is a possibility that the paper has wrapped around the heating roll 62 (in other words, if there is a high possibility that the paper has wrapped around the heating roll 62), the process proceeds to step S210. On the other hand, if there is no possibility that the paper has wrapped around the heating roll 62 (in other words, if there is a low possibility that the paper has wrapped around the heating roll 62), the image forming apparatus 20 enters a standby state until the recovery process is executed.

[0072] Next, when there is a possibility that the paper may be wrapped around the heating roll 62, the CPU 101 increases the cooling capacity of the cooling device 70 (step S210). Specifically, when there is a possibility that the paper may be wrapped around the heating roll 62, the CPU 101 rotates the intake fan 72 and the exhaust fan 74 of the cooling device 70 at high speed. This increases the speed of the air flowing from the intake fan 72 to the exhaust fan 74 inside the housing 66 of the fixing unit 60, and the heat of the heating roll 62, which is in the middle of the air flow, is rapidly removed and cooled. Then, the image forming apparatus 20 goes into a standby state with the intake fan 72 and the exhaust fan 74 rotating at high speed until the recovery process is executed.

[0073] Next, the flow of the first detection process for detecting wrapping of the paper P will be described with reference to FIG.

[0074] When the first detection process is executed, the CPU 101 first stores the current temperature of the fixing unit 60 (step S250). Specifically, the CPU 101 stores the temperature information of the heating roll 62 in the memory 102 or the storage device 103. More specifically, the CPU 101 stores the temperature information of each temperature sensor 103 in the memory 102 or the storage device 103.

[0075] Next, the CPU 101 starts a temperature drop monitoring timer (step S252). A predetermined time is set in this temperature drop monitoring timer. Specifically, the CPU 101 stores the temperature information of the heating roll 62 so that the temperature information of the heating roll 62 stored in step S250 becomes the temperature at the start of the temperature drop monitoring timer, and starts the temperature drop monitoring timer.

[0076] Next, CPU 101 determines whether the temperature drop monitoring timer has ended (step S254). Specifically, CPU 101 determines whether a predetermined time has elapsed since the start of the temperature drop monitoring timer, in other words, whether the end time has been reached. If the temperature drop monitoring timer has reached the end time, the process proceeds to step S256. On the other hand, if the temperature drop monitoring timer has not reached the end time, step S254 is repeated.

[0077] When the temperature drop monitoring timer ends, the CPU 101 stores the current temperature of the fixing unit 60 (step S256). Specifically, the CPU 101 stores the temperature information of the heating roll 62 in the memory 102 or the storage device 103, similar to step S250. More specifically, the CPU 101 stores the temperature information of each temperature sensor 103 in the memory 102 or the storage device 103. Here, the CPU 101 stores the temperature information of the heating roll 62 so that the temperature information of the heating roll 62 stored in step S256 becomes the temperature at the end of the temperature drop monitoring timer.

[0078] Next, CPU 101 calculates the temperature gradient based on the elapsed time measured by the temperature drop monitoring timer and the temperature change of fixing unit 60 (step S258). Specifically, CPU 101 calculates the temperature gradient based on the time preset in the temperature drop monitoring timer, the temperature at the start of the temperature drop monitoring timer, and the temperature at the end of the temperature drop monitoring timer. In this embodiment, the temperature gradient is calculated based on temperature information from first temperature sensor 68A. Note that the present disclosure is not limited to this configuration. The temperature gradient may be calculated based on the average value of each temperature sensor 68, or in some other way.

[0079] Next, the CPU 101 judges whether the temperature gradient value (hereinafter, appropriately referred to as the "temperature drop gradient value") calculated in step S258 is equal to or less than the first detection threshold (step S260). Specifically, the CPU 101 judges whether the temperature drop gradient value is equal to or less than the first detection threshold set in advance. The first detection threshold is a threshold set based on the temperature gradient when the paper P is wrapped around the heating roll 62. When the paper P is wrapped around the heating roll 62, the temperature gradient value becomes lower than when the paper P is not wrapped around the heating roll 62. If the temperature drop gradient value is judged to be equal to or less than the first detection threshold, there is a possibility that the paper is wrapped around the heating roll 62 (in other words, the possibility of the paper wrapping is high), so the process proceeds to step S262. On the other hand, if the temperature drop gradient value is not judged to be equal to or less than the first detection threshold, in other words, if the temperature drop gradient value is judged to be greater than the first detection threshold, there is no possibility that the paper is wrapped around the heating roll 62 (in other words, the possibility of the paper wrapping is low), so the first detection process is terminated and the process proceeds to step S208.

[0080] Next, when CPU 101 determines in step S260 that the temperature drop gradient value is equal to or less than the first detection threshold, in step S262, it sets that there is a possibility of paper wrapping. Specifically, CPU 101 stores the possibility of paper wrapping in memory 102 or storage device 103. After executing step S262, the first detection process ends and the process proceeds to step S208.

[0081] Next, a flow of the recovery process in the image forming apparatus 20 of this embodiment will be described with reference to Fig. 7. First, when all the open covers, etc. are closed to clear a paper jam, the recovery process of the image forming apparatus 20 starts. The recovery process includes a warm-up process, which will be described later.

[0082] When all covers are closed, the CPU 101 included in the image forming apparatus 20 first determines whether each paper sensor 90 is off (step S300). Specifically, if each paper sensor 90 is off, that is, if the paper P is not being detected, the CPU 101 proceeds to step S302. On the other hand, if all the paper sensors 90 are not off, the recovery process is interrupted and terminated.

[0083] Next, CPU 101 determines whether or not there is a possibility of paper wrapping (step S302). Specifically, if the possibility of paper wrapping is set in the first detection process, CPU 101 determines that there is a possibility of paper wrapping in step S302. If there is a possibility of paper wrapping, the process proceeds to step S304. On the other hand, if there is no possibility of paper wrapping, the process proceeds to step S308.

[0084] Next, CPU 101 determines whether the temperature of fixing unit 60 is equal to or lower than the paper winding detection start temperature (hereinafter referred to as "detection start temperature" where appropriate) (step S304). Specifically, CPU 101 determines whether the temperature of heating roll 62 is equal to or lower than a preset detection start temperature. If it is equal to or lower than the detection start temperature, the process proceeds to step S306. On the other hand, if it exceeds the detection start temperature, step S304 is repeated. In this manner, step S304 is repeated until the temperature of heating roll 62 is equal to or lower than the detection start temperature. Note that when it is set that there is a possibility of paper winding, both intake fan 72 and exhaust fan 74 are rotating at high speed. This improves the cooling speed of heating roll 62.

[0085] Next, the CPU 101 changes the high speed rotation of the intake fan 72 and the exhaust fan 74 to normal rotation (step S306). Note that the high speed rotation and normal rotation are set in advance.

[0086] Next, the CPU 101 starts a warm-up process for the fixing unit 60 (step S308). Specifically, the CPU 101 turns on each lamp 63 in the heating roll 62 to increase the temperature of the heating roll 62. The temperature information detected by each temperature sensor 68 is stored in the memory 102 or the storage device 103.

[0087] Next, the CPU 101 executes a second detection process to detect the wrapping of the paper P around the heating roll 62 (step S310). In the second detection process, it is determined whether the paper P has wrapped around the heating roll 62. The second detection process will be described in detail later.

[0088] When the execution of the second detection process is completed, the CPU 101 determines whether or not the paper is wrapped around the heating roll 62 (step S312). Specifically, the CPU 101 determines whether or not the paper is wrapped around the heating roll 62 from the result of the second detection process. If the paper is wrapped around the heating roll 62, the process proceeds to step S314. On the other hand, if the paper is not wrapped around the heating roll 62, the process proceeds to step S318.

[0089] Next, in step S312, if the paper is wrapped around the heating roll 62, the CPU 101 stops the drive motor 67 and each lamp 63 of the fixing unit 60 (step S314). Specifically, the CPU 101 stops the power supply to the drive motor 67 and each lamp 63.

[0090] Next, the CPU 101 stops the drive motor 67 of the fixing unit 60 and each lamp 63, and then notifies a display unit (not shown) such as a display provided in the image forming apparatus 20 that paper has wrapped around the paper (step S316). Then, the CPU 101 suspends and ends the recovery process.

[0091] Furthermore, in step S312, if there is no paper wrapping around the heating roll 62, the CPU 101 determines whether the temperature of the fixing unit 60 has reached the standby temperature (step S318). Specifically, if there is no paper wrapping, the CPU 101 determines whether the temperature of the heating roll 62 has reached a preset standby temperature. If the temperature of the heating roll 62 has reached the standby temperature, the recovery process of the image forming apparatus 20 is completed. Completion of the recovery process puts the image forming apparatus 20 in a printable state. On the other hand, if the temperature of the heating roll 62 has not reached the standby temperature, step S318 is repeated. That is, step S318 is repeatedly executed until the temperature of the heating roll 62 reaches the standby temperature.

[0092] Next, the flow of the second detection process for detecting wrapping of the paper P will be described with reference to FIG.

[0093] When the second detection process is executed, the CPU 101 first determines whether or not the temperature of the fixing unit 60 has reached the detection start temperature (step S350).

[0094] Next, the CPU 101 starts the temperature rise start time timer (step S352).

[0095] Next, CPU 101 determines whether the temperature of fixing unit 60 has reached the temperature rise start temperature (step S354). Specifically, CPU 101 determines whether the temperature of heating roll 62 has reached the temperature rise start temperature. If the temperature of heating roll 62 has reached the temperature rise start temperature, the process proceeds to step S356. On the other hand, if the temperature of heating roll 62 has not reached the temperature rise start temperature, step S354 is repeated. This step S354 is repeatedly executed until the temperature of heating roll 62 reaches the temperature rise start temperature.

[0096] Next, the CPU 101 stops the temperature rise start time timer and saves the temperature rise start time (step S356). Specifically, the CPU 101 stores the temperature rise start time in the memory 102 or the storage device 103.

[0097] Next, CPU 101 determines whether the temperature rise start time is equal to or greater than the temperature rise start time threshold (step S358). The temperature rise start time threshold is a preset threshold for the temperature rise start time. If it is determined that the temperature rise start time is equal to or greater than the temperature rise start time threshold, the process proceeds to step S360. On the other hand, if it is determined that the temperature rise start time is less than the temperature rise start time threshold, the process proceeds to step S368.

[0098] Next, when CPU 101 determines that the temperature rise start time is equal to or greater than the temperature rise start time threshold, it starts a temperature rise rate timer (step S360).

[0099] Next, CPU 101 determines whether the temperature of fixing unit 60 has reached the temperature rise measurement end temperature (step S362). Specifically, CPU 101 determines whether the temperature of heating roll 62 has reached the temperature rise measurement end temperature. If the temperature of heating roll 62 has reached the temperature rise measurement end temperature, the process proceeds to step S364. On the other hand, if the temperature of heating roll 62 has not reached the temperature rise measurement end temperature, step S362 is repeated. This step S362 is repeatedly executed until the temperature of heating roll 62 reaches the temperature rise measurement end temperature.

[0100] Next, the CPU 101 stops the temperature rise rate timer, and saves the temperature rise rate (temperature rise gradient) (step S364). Specifically, the CPU 101 stores the temperature rise rate in the memory 102 or the storage device 103.

[0101] Next, as shown in Fig. 11, CPU 101 determines whether the temperature rise rate is equal to or greater than the temperature rise rate threshold (step S366). The temperature rise rate threshold is a preset threshold for the temperature rise rate. If it is determined that the temperature rise rate is equal to or greater than the temperature rise rate threshold, there is no paper wrapping, so the first detection process ends and the process proceeds to step S312. On the other hand, if it is determined that the temperature rise rate is less than the temperature rise rate, the process proceeds to step S368.

[0102] Next, when CPU 101 determines in step S366 that the temperature increase rate is less than the temperature increase rate, it sets in step S366 that there is paper wrapping. Specifically, CPU 101 stores the presence of paper wrapping in memory 102 or storage device 103. After executing step S366, the second detection process ends and the process proceeds to step S312.

[0103] As described above, in the image forming apparatus 20 of this embodiment, the first detection process determines whether or not there is a possibility of paper wrapping, and the second detection process determines whether or not there is paper wrapping. Specifically, the image forming apparatus 20 determines whether or not there is a possibility of paper wrapping when the temperature of the fixing unit 60 drops, and determines whether or not there is paper wrapping when the temperature of the fixing unit 60 rises. In other words, the image forming apparatus 20 determines whether or not there is a possibility of paper wrapping when the temperature of the fixing unit 60 drops, which is caused by many disturbance factors, and determines whether or not there is paper wrapping when the temperature rises, which is caused by fewer disturbance factors compared to when the temperature drops, and therefore can accurately determine whether or not there is paper wrapping around the heating roll 62.

[0104] Next, the effects of this embodiment will be described.

[0105] As described above, in the image forming apparatus 20 of this embodiment, when a jam of the paper P occurs in the fixing section 60, the image forming apparatus 20 judges whether the paper P is wrapped around the heating roll 62 based on the temperature rise gradient (temperature rise rate). Therefore, the image forming apparatus 20 can judge whether the paper P is wrapped around the heating roll 62 with higher accuracy than an apparatus that judges whether the paper P is wrapped around the heating roll 62 based on the temperature fall gradient.

[0106] In addition, in the image forming device 20, when a jam of the paper P occurs in the fixing section 60, it is possible to accurately determine whether or not the paper P is wrapped around the heating roll 62, compared to determining that the paper P is not wrapped around the heating roll when the temperature rise gradient value is below a predetermined second detection threshold value.

[0107] Furthermore, in the image forming apparatus 20, when a jam of the paper P occurs in the fixing section 60, the paper wrapping is determined based on the temperature drop gradient (first detection process) and the temperature rise gradient (second detection process). Therefore, the image forming apparatus 20 can determine the presence or absence of the recording medium wrapping around the heating roll with higher accuracy than when the image forming apparatus 20 determines the presence or absence of the paper wrapping based only on the temperature rise gradient.

[0108] In addition, in the image forming device 20, when a jam of the paper P occurs in the fixing section 60, it is possible to accurately determine whether or not the paper P has wrapped around the heating roll 62, compared to determining that there is no possibility of the paper P wrapping around the heating roll 62 when the temperature decrease / increase gradient value is below a predetermined first detection threshold value.

[0109] Furthermore, in the image forming apparatus 20, whether or not the paper P is wrapped around the heating roll 62 can be determined with higher accuracy than in a case where a constant gradient is used as the threshold value regardless of the size and thickness of the paper P.

[0110] In addition, in the image forming device 20, the recovery speed of the device after the jam of the paper P is cleared can be increased compared to when the temperature of the fixing section 60 is lowered below the temperature at which the image can be fixed after it is determined that the paper P is not wrapped around the paper P.

[0111] Furthermore, the image forming apparatus 20 can have a simpler device configuration than one that uses a liquid-cooling type cooling means.

[0112] Moreover, in the image forming apparatus 20, the cooling speed of the fixing unit 60 can be increased compared to an image forming apparatus in which only one of the intake fan 72 and the exhaust fan 74 is provided in the fixing unit 60.

[0113] (Other embodiments) 12 and 13, the CPU 101 may execute the following detection process during or following the second detection process during the recovery process. Specifically, when a jam of the paper P occurs in the fixing unit 60, the CPU 101 stops heating the heating roll 62, and when the fixing unit 60 becomes equal to or lower than a predetermined temperature, the CPU 101 reheats the heating roll 62, and measures the time from when the fixing unit 60 becomes equal to or lower than the predetermined temperature to when the heating roll 62 is reheated, and when the measured time exceeds a predetermined winding time, it may determine that the paper P is wrapped around the paper P. Specifically, the CPU 101 first determines whether or not the second detection process is being executed (step S400). If the second detection process is being executed, the process proceeds to step S402, and if the second detection process is not being executed, the process stops the detection process and proceeds to step S208. In step S402, the CPU 101 determines whether or not the fixing unit 60 has reached a predetermined target temperature. If the fixing unit 60 has reached the predetermined target temperature, the process proceeds to step S404. On the other hand, if the fixing unit 60 has not reached the predetermined target temperature, step S402 is repeated. Next, in step S404, the CPU 101 turns off the lamp 63. That is, the heating of the heating roll 62 is stopped. Then, the CPU 101 starts the measurement timer T (step S406). Next, the CPU 101 judges whether the temperature of the fixing unit 60 is lower than the target temperature (step S408). If the temperature of the fixing unit 60 is lower than the target temperature, the process proceeds to step S410. On the other hand, if the temperature of the fixing unit 60 is equal to or higher than the target temperature, step S408 is repeated. Then, in step S410, the CPU 101 turns off the lamp 63. That is, the heating of the heating roll 62 is started. Next, the CPU 101 stops the measurement timer T (step S412). Then, the CPU 101 judges whether the measurement timer T is equal to or higher than the predetermined T threshold value. If the measurement timer T is equal to or greater than the predetermined threshold T, the process proceeds to step S416. On the other hand, if the measurement timer T is less than the predetermined threshold T, the process stops and ends the detection process, and the process proceeds to step S208. In step S416, the CPU 101 sets that there is paper wrapping, the detection process ends, and the process proceeds (returns) to step S208.By carrying out the above-mentioned detection process, the accuracy of detecting the wrapping of the paper is further improved.

[0114] The present disclosure is not limited to the above-described embodiment, and various modifications, changes, and improvements are possible without departing from the spirit and scope of the present disclosure. For example, the above-described modified examples may be appropriately combined to form a configuration.

[0115] The following is further disclosed regarding the above embodiment.

[0116] (((1))) a fixing section including a heating roll for heating the recording medium and a pressure roll for pressing the recording medium together with the heating roll, and fixing an image onto the recording medium; A detection means for detecting the temperature of the fixing unit; A cooling means for cooling the fixing unit; a processor for controlling the fixing unit and the cooling unit based on temperature information obtained from the detection unit; Equipped with The processor, When a jam of the recording medium occurs in the fixing unit and there is a possibility that the recording medium may be wrapped around the heating roll, the cooling capacity of the cooling means is increased, When the temperature of the fixing unit reaches a predetermined temperature or lower, the temperature of the fixing unit is increased, and the presence or absence of wrapping of the recording medium is determined from the temperature increase gradient based on the temperature information. Image forming device. (((2))) The processor, The image forming apparatus according to (((1))), wherein, when the temperature rise gradient value is equal to or less than a predetermined threshold value, it is determined that the recording medium is wrapped around the heating roll. (((3))) The processor, When a jam of the recording medium occurs in the fixing unit, Stop heating the heating roll; The image forming apparatus according to (((1))) determines whether or not there is a possibility of the recording medium wrapping from a temperature drop gradient based on the temperature information. (((4))) The processor, The image forming apparatus according to (((3))), wherein if the temperature drop gradient value is equal to or less than a predetermined threshold value, it is determined that there is a possibility that the recording medium will wrap around the heating roll. (((5))) The processor, The image forming apparatus according to ((4))), wherein the predetermined threshold value is changed based on at least one of the size and the thickness of the recording medium. (((6))) The processor, When the fixing unit reaches or exceeds a predetermined temperature, the temperature of the fixing unit is increased, and the presence or absence of wrapping of the recording medium is determined from a temperature increase gradient based on the temperature information. If it is determined that the recording medium is not wrapped around the recording medium, the temperature of the fixing unit is maintained at or above a temperature at which an image can be fixed to the recording medium (((1))). (((7))) the cooling unit is a cooling fan that blows air to the fixing unit, The image forming apparatus according to (((1))), wherein the processor controls a rotation speed of the cooling fan. (((8))) The image forming apparatus according to ((7)) above, wherein the cooling fans are disposed upstream and downstream of the fixing unit in a transport direction of the recording medium. (((9))) The processor, When a jam of the recording medium occurs in the fixing unit, Stop heating the heating roll; The image forming apparatus according to any one of (((1))) to (((8))) above, wherein when the fixing unit reaches a predetermined temperature or below, the heating roll is reheated, and the time from when the fixing unit reaches a predetermined temperature or below to when the heating roll is reheated is measured, and when the measured time exceeds a predetermined winding time, it is determined that the recording medium has wrapped around the recording medium.

[0117] In the image forming apparatus (((1))), when a recording medium becomes clogged in the fixing section, it is possible to more accurately determine whether or not the recording medium is wrapped around the heating roll, compared to an apparatus which determines whether or not the recording medium is wrapped around the heating roll based on a temperature drop gradient. In the image forming apparatus (((2))), when a recording medium becomes clogged in the fixing section, it is possible to accurately determine whether or not the recording medium is wrapped around the heating roll, compared to an apparatus that determines that the recording medium is not wrapped around the heating roll when the temperature rise gradient value is below a predetermined threshold value. In the image forming apparatus (((3))), when a recording medium becomes clogged in the fixing section, it is possible to more accurately determine whether or not the recording medium is wrapped around the heating roll, compared to a case in which this is determined based only on the temperature rise gradient. In the image forming apparatus (((4))), when a recording medium becomes clogged in the fixing unit, it is possible to accurately determine whether or not the recording medium has wrapped around the heating roll, compared to an apparatus which determines that there is no possibility of the recording medium wrapping around the heating roll when the temperature drop gradient value is equal to or below a predetermined threshold value. In the image forming apparatus (((5))), it is possible to more accurately determine whether or not the recording medium is wrapped around the heating roll, compared to an apparatus that uses a constant gradient as a threshold value regardless of the size and thickness of the recording medium. In the image forming apparatus (((6))), the recovery speed of the apparatus after a recording medium jam is cleared can be increased, compared to an apparatus in which the temperature of the fixing unit is lowered below the temperature at which an image can be fixed after it is determined that there is no wrapping of the recording medium. In the image forming apparatus of (((7))), the apparatus configuration can be simplified compared to an apparatus that uses a liquid-cooling type cooling means. In the image forming apparatus (((8))), the cooling speed of the fixing unit can be increased compared to an apparatus in which the cooling fan is disposed only upstream or downstream of the fixing unit in the transport direction of the recording medium. In the image forming apparatus (((9))), it is possible to more accurately determine whether or not the recording medium is wrapped around the heating roll, compared to an apparatus that determines whether or not the recording medium is wrapped around the heating roll based only on the temperature rise gradient. [Explanation of symbols]

[0118] 20 Image forming device 60 Fixing unit 62 Heating Roll 64 Pressure Roll 68 Temperature sensor (an example of a detection means) 70 Cooling device (an example of a cooling means) 72 Intake fan (an example of a cooling fan) 74 Exhaust fan (an example of a cooling fan) 101 CPU (an example of a processor) P Paper (an example of a recording medium)

Claims

1. a fixing section including a heating roll for heating a recording medium and a pressure roll for pressing the recording medium together with the heating roll, and fixing an image onto the recording medium; A detection means for detecting the temperature of the fixing unit; A cooling means for cooling the fixing unit; a processor for controlling the fixing unit and the cooling unit based on temperature information obtained from the detection unit; Equipped with The processor, When a jam of the recording medium occurs in the fixing unit and there is a possibility that the recording medium may be wrapped around the heating roll, the cooling capacity of the cooling means is increased, When the temperature of the fixing unit reaches a predetermined temperature or lower, the temperature of the fixing unit is increased, and the presence or absence of wrapping of the recording medium is determined from the temperature increase gradient based on the temperature information. Image forming device.

2. The processor, When the temperature rise gradient value is equal to or less than a predetermined threshold value, it is determined that the recording medium is wrapped around the heating roll. The image forming apparatus according to claim 1 .

3. The processor, When a jam of the recording medium occurs in the fixing unit, Stop heating the heating roll; The possibility of the recording medium wrapping is judged from a temperature drop gradient based on the temperature information. The image forming apparatus according to claim 1 .

4. The processor, When the temperature drop gradient value is equal to or less than a predetermined threshold value, it is determined that there is a possibility that the recording medium may wrap around the heating roll. The image forming apparatus according to claim 3 .

5. The processor, The predetermined threshold is changed based on at least one of the size and the thickness of the recording medium. The image forming apparatus according to claim 4 .

6. The processor, When the temperature of the fixing unit reaches a predetermined temperature or lower, the temperature of the fixing unit is increased, and the presence or absence of wrapping of the recording medium is determined from a temperature increase gradient based on the temperature information, and when it is determined that the wrapping is not present, the temperature of the fixing unit is maintained at a temperature at which an image can be fixed to the recording medium or higher. The image forming apparatus according to claim 1 .

7. the cooling unit is a cooling fan that blows air to the fixing unit, The processor controls the rotation speed of the cooling fan. The image forming apparatus according to claim 1 .

8. The cooling fans are disposed on the upstream side and downstream side of the fixing unit in the conveying direction of the recording medium. The image forming apparatus according to claim 7.

9. The processor, When a jam of the recording medium occurs in the fixing unit, Stop heating the heating roll; When the fixing section becomes equal to or lower than a predetermined temperature, the heating roll is reheated, and the time from when the fixing section becomes equal to or lower than the predetermined temperature to when the heating roll is reheated is measured. When the measured time exceeds a predetermined winding time, it is determined that the recording medium has wrapped around the recording medium. The image forming apparatus according to any one of claims 1 to 8.

Images