JP2021033183A - Fixing device, image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine a slip occurrence state of a pressure member with respect to a sliding member in a fixing device while suppressing an increase in cost due to addition of parts. A fixing device 48 includes a heater 51, a sliding member 53, a pressurizing member 6, a driving device, a temperature sensor 57, a control unit, and a slip determination unit. The temperature sensor 57 measures the temperature of the sliding member 53. The control unit operates the heater 51 with the pressurizing member 6 stopped, and then operates the driving device to rotate the pressurizing member 6 at a constant speed. The slip determination unit determines the slip occurrence status of the pressurizing member 6 with respect to the sliding member 53 based on the time interval of the peak of the measured temperature of the temperature sensor 57 when the pressurizing member 6 is rotating. judge. [Selection diagram] Fig. 2

Description

The present invention relates to a fixing device for fixing a toner image on a sheet and an image forming device including the fixing device.

The electrophotographic image forming apparatus includes a fixing apparatus that heats and pressurizes the toner image transferred to the sheet. Further, the fixing device forms a nip through which a sheet passes between a heater composed of a plurality of heating elements arranged along the width direction, a tubular sliding member including the heater, and the sliding member. May be equipped with a pressurizing roller.

When the pressure roller rotates, the sliding member rotates drivenly, and the inner peripheral surface of the sliding member slides in the sheet transport direction with respect to the surface of the heater. A lubricant is applied to the inner peripheral surface of the sliding member.

The sliding member deteriorates due to wear, deterioration of the lubricant over time, or contamination of the inner peripheral surface of the sliding member with foreign matter. Deterioration of the sliding member manifests itself as an increase in frictional resistance between the sliding member and the heater.

When the frictional resistance between the sliding member and the heater increases, slip of the pressure roller with respect to the sliding member occurs. This slip causes poor image quality.

Further, in the fixing device, it is known that the estimated life of the sliding member is determined based on the difference between the starting torque of the motor that drives the pressurizing roller and the driving torque after the motor is started. (See, for example, Patent Document 1).

JP-A-2018-31836

By the way, in the fixing device, it is important to determine whether or not the pressurizing roller has slipped in order to avoid poor image quality.

For example, in order to detect the slip occurrence state of the pressure roller, it is conceivable to provide a rotation measurement mechanism that mechanically or optically measures the rotation speed of the sliding member. However, if the rotation measuring mechanism is provided, a plurality of additional parts and mechanical adjustment of the plurality of additional parts are required. This is not preferable in terms of cost.

An object of the present invention is to provide a fixing device and an image forming device capable of determining a slip occurrence state of a pressure member with respect to a sliding member in the fixing device while suppressing an increase in cost due to the addition of parts.

The fixing device according to one aspect of the present invention is a device for fixing the toner image to the sheet by heating and pressurizing the toner image on the sheet at the fixing position of the sheet transport path. The fixing device includes a heater, a sliding member, a pressurizing member, a driving device, a temperature sensor, a control unit, and a slip determination unit. The heater is arranged along the width direction orthogonal to the sheet transport direction at the fixing position. The sliding member is a tubular member that includes the heater, and the inner peripheral surface that is rotatably supported and coated with a lubricant by rotation is along the sheet transport direction with respect to the surface of the heater. Sliding. The pressurizing member is rotatably supported and urged toward the heater to form a nip through which the sheet passes between the pressurizing member and the sliding member. The driving device rotationally drives the sliding member. The temperature sensor measures the temperature of the sliding member. The control unit operates the heater in a state where the pressurizing member is stopped, and then operates the driving device to rotate the pressurizing member at a constant speed. The slip determination unit determines the occurrence state of slip of the pressurizing member with respect to the sliding member based on the time interval of the peak of the measured temperature of the temperature sensor when the pressurizing member is rotating.

An image forming apparatus according to another aspect of the present invention includes a transfer device for transferring a toner image to a sheet and the fixing device for fixing the toner image to the sheet.

According to the present invention, it is possible to provide a fixing device and an image forming device capable of determining a slip occurrence state of a pressure member with respect to a sliding member in the fixing device while suppressing an increase in cost due to the addition of parts. ..

FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment. FIG. 2 is a configuration diagram of a fixing device in the image forming device according to the embodiment. FIG. 3 is a block diagram showing a configuration of a control device in the image forming device according to the embodiment. FIG. 4 is a graph showing an example of a change in the measured temperature in the fixing device when the slip determination process is performed in the image forming device according to the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are examples that embody the present invention, and do not limit the technical scope of the present invention.

[Structure of image forming apparatus 10]
The image forming apparatus 10 according to the embodiment is an apparatus that performs a printing process for forming an image on the sheet 9. The image forming apparatus 10 performs the printing process by an electrophotographic method. The sheet 9 is an image forming medium such as paper or a sheet-shaped resin member.

As shown in FIG. 1, the image forming apparatus 10 includes a sheet transporting apparatus 3 and a printing apparatus 40 provided in the main body 1, a control apparatus 8, an operating apparatus 801 and a display apparatus 802.

The sheet transfer device 3 includes a sheet delivery device 30 and a plurality of sets of transfer roller pairs 31. The sheet delivery device 30 sends the sheet 9 accommodated in the sheet accommodating portion 2 to the transport path 300 in the main body portion 1.

The plurality of sets of transport roller pairs 31 are rotationally driven by a motor and rotate with the seat 9 sandwiched between them to transport the seat 9 along the transport path 300. Further, the plurality of sets of transport roller pairs 31 discharge the sheet 9 from the outlet of the transport path 300 to the discharge tray 101. In the following description, the direction in which the sheet 9 is conveyed along the transfer path 300 is referred to as the sheet transfer direction D1. Further, the direction orthogonal to the sheet transport direction D1 and along the transport path 300 is referred to as a width direction D2.

The printing device 40 forms a toner image on the sheet 9 transported along the transport path 300 by the sheet transport device 3. The printing device 40 includes an image forming device 4, an optical scanning device 46, a transfer device 47, and a fixing device 48. The image forming apparatus 4 includes a drum-shaped photoconductor 41, a charging apparatus 42, a developing apparatus 43, a drum cleaning apparatus 45, and the like.

The image forming apparatus 10 shown in FIG. 1 is a tandem type color image forming apparatus. Therefore, the printing device 40 includes four image forming devices 4 corresponding to the four color toners of yellow, cyan, magenta, and black. Further, the transfer device 47 includes an intermediate transfer belt 471, four belt transfer devices 472 corresponding to the four image forming devices 4, a sheet transfer device 473, and a belt cleaning device 474.

In the image forming apparatus 4, the photoconductor 41 rotates, and the charging device 42 charges the surface of the photoconductor 41. Further, the optical scanning device 46 writes an electrostatic latent image on the surface of the photoconductor 41 by scanning the laser beam. The photoconductor 41 is an example of an image carrier.

Further, the developing apparatus 43 supplies the toner to the surface of the photoconductor 41 to develop the electrostatic latent image as a toner image.

The transfer device 47 transfers the toner image to the sheet 9 in the transport path 300. In the transfer device 47, the belt transfer device 472 transfers the toner image on the surface of the photoconductor 41 to the surface of the intermediate transfer belt 471. As a result, the color toner image is formed on the surface of the intermediate transfer belt 471.

The sheet transfer device 473 transfers the toner image formed on the intermediate transfer belt 471 to the sheet 9 in the transport path 300.

When the image forming apparatus 10 is a monochrome image forming apparatus, the sheet transfer apparatus 473 transfers the toner image on the photoconductor 41 to the sheet 9 in the transport path 300.

The drum cleaning device 45 removes the toner remaining on the surface of the photoconductor 41. The belt cleaning device 474 removes the toner remaining on the intermediate transfer belt 471.

The fixing device 48 fixes the toner image on the sheet 9 by heating and pressurizing the toner image transferred to the sheet 9 at the fixing position P1 of the transport path 300.

The fixing device 48 includes a heating device 5, a pressurizing roller 6, a motor 60, and a motor drive circuit 61. The heating device 5 includes a heater 51, a support member 52, a sliding member 53, and a heater power supply circuit 50.

The sliding member 53 is a tubular flexible member. The pressure roller 6 is a roller in which a layer of an elastic member such as rubber is formed on the surface layer.

The heater 51 is arranged along the width direction D2 at the fixing position P1. For example, the heater 51 is composed of a plurality of heating elements arranged along the width direction D2. Each of the heating elements generates heat when electric power is supplied.

The support member 52 is a member that supports the heater 51. The heater 51 and the support member 52 are arranged so that the longitudinal direction is along the width direction D2. The heater 51 heats the sliding member 53.

The sliding member 53 is a flexible tubular member. That is, the sliding member 53 is an endless belt-shaped member. For example, the sliding member 53 is a tubular film member.

The sliding member 53 is rotatably supported so as to include the heater 51 and the support member 52. For example, as shown in FIG. 2, the fixing device 48 includes a pair of guide members 55 having an upright portion 55a along an arc.

The pair of guide members 55 are supported in a state in which each of the upright portions 55a faces both end portions in the width direction D2 on the inner peripheral surface of the sliding member 53. As a result, the pair of guide members 55 rotatably support the sliding member 53.

Since the sliding member 53 rotates around the heater 51 and the support member 52, the inner peripheral surface of the sliding member 53 slides with respect to the surface of the heater 51 along the sheet transport direction D1. A lubricant 54 is applied to the inner peripheral surface of the sliding member 53.

The heater 51 heats the sliding member 53. The heater 51 is an example of a base member in contact with the inner peripheral surface of the sliding member 53. That is, the heater 51 is a heat generating member that heats the sliding member 53, and is also the base member that is in contact with the inner peripheral surface of the base member.

The pressurizing roller 6 is rotatably supported in a state of being urged toward the heater 51. For example, the pressurizing roller 6 is urged toward the heater 51 by a spring (not shown). The toner image on the sheet 9 is heated by the heater 51 and pressurized by the pressurizing roller 6. The pressurizing roller 6 is an example of a pressurizing member.

The pressure roller 6 forms a nip Np1 through which the sheet 9 passes between the pressure roller 6 and the sliding member 53. The position where the nip Np1 is formed is the fixing position P1.

The motor 60 is an example of a drive device that rotationally drives the pressurizing roller 6. The motor drive circuit 61 supplies electric power to the motor 60 so that the motor 60 rotates constantly at a predetermined rotation speed. As a result, the pressurizing roller 6 rotates at a predetermined constant speed. For example, the motor drive circuit 61 is an inverter drive circuit.

As the pressure roller 6 rotates, the sliding member 53 is driven to rotate with respect to the pressure roller 6. That is, the pressure roller 6 rotates to rotate the sliding member 53 in a driven manner.

The heater power supply circuit 50 supplies electric power to the heater 51 in accordance with a command from the control device 8. Further, the heater power supply circuit 50 adjusts the amount of power supplied to the heater 51 in accordance with a command from the control device 8.

Further, the heating device 5 further includes a fixing temperature sensor 56 that measures the temperature of the heater 51. The fixing temperature sensor 56 is a temperature sensor used for feedback control for maintaining the temperature of the heater 51 at a preset target temperature. For example, the fixing temperature sensor 56 is a thermistor.

The fixing temperature sensor 56 measures the temperature of the fixing position P1, that is, the temperature which is an alternative index of the temperature of the nip Np1. Therefore, the fixing temperature sensor 56 may be arranged at a position where the temperature of the sliding member 53 is measured.

The operation device 801 is a device that accepts human operations, and includes, for example, operation buttons and a touch panel. The display device 802 is a device that displays information, and includes, for example, a panel display device such as a liquid crystal display unit.

The control device 8 executes various data processing and controls of devices such as the sheet transfer device 3, the printing device 40, and the display device 802.

As shown in FIG. 3, the control device 8 includes a CPU (Central Processing Unit) 81 and peripheral devices such as a RAM (Random Access Memory) 82, a secondary storage device 83, and a signal interface 84.

The CPU 81 is a processor that executes various data processing and control by executing a computer program. The RAM 82 is a computer-readable volatile storage device. The RAM 82 primarily stores the computer program executed by the CPU 81 and data to be output and referenced in the process of executing various processes by the CPU 81.

The CPU 81 includes a plurality of processing modules realized by executing the computer program. The plurality of processing modules include a main control unit 8a, a temperature control unit 8b, a transfer control unit 8c, a print control unit 8d, and the like.

The main control unit 8a executes start control for starting various processes in response to an operation on the operation device 801 and control for the display device 802.

The temperature control unit 8b adjusts the amount of power supplied to the heating device 5 by feedback control based on the comparison between the measured temperature of the fixing temperature sensor 56 and the preset target temperature. The temperature control unit 8b adjusts the amount of power supplied to the heating device 5 by controlling the heater power supply circuit 50.

The transfer control unit 8c controls the sheet transfer device 3. The print control unit 8d causes the printing device 40 to execute the printing process in synchronization with the transfer of the sheet 9.

The secondary storage device 83 is a computer-readable non-volatile storage device. The secondary storage device 83 can store and update the computer program and various data. For example, one or both of the flash memory and the hard disk drive are adopted as the secondary storage device 83.

The signal interface 84 converts signals output by various sensors such as the fixing temperature sensor 56 into digital data, and transmits the converted digital data to the CPU 81. Further, the signal interface 84 converts the control command output by the CPU 81 into a control signal, and transmits the control signal to the device to be controlled.

The sliding member 53 of the fixing device 48 deteriorates due to wear, deterioration of the lubricant 54 over time, or contamination of the inner peripheral surface of the sliding member 53 with foreign matter. Deterioration of the sliding member 53 manifests itself as an increase in frictional resistance between the sliding member 53 and the heater 51.

When the frictional resistance between the sliding member 53 and the heater 51 increases, the pressure roller 6 slips on the sliding member 53. This slip causes poor image quality.

By the way, in the fixing device 48, it is important to determine whether or not the pressurizing roller 6 has slipped in order to avoid poor image quality.

For example, in order to detect the slip occurrence state of the pressure roller 6, it is conceivable to provide a rotation measurement mechanism that mechanically or optically measures the rotation speed of the sliding member 53. However, if the rotation measuring mechanism is provided, a plurality of additional parts and mechanical adjustment of the plurality of additional parts are required. This is not preferable in terms of cost.

On the other hand, in the present embodiment, the fixing device 48 includes the ripple temperature sensor 57 shown in FIG. 2 and executes the slip determination process described later. As a result, the fixing device 48 can determine the state of occurrence of slip of the pressure roller 6 with respect to the sliding member 53 while suppressing an increase in cost due to the addition of parts.

The ripple temperature sensor 57 is a temperature sensor that measures the temperature of the sliding member 53. In the example shown in FIG. 2, the ripple temperature sensor 57 is supported by a support member 52 that supports the heater 51.

That is, the support member 52 is arranged inside the sliding member 53 and supports the heater 51 and the ripple temperature sensor 57. As shown in FIG. 2, the ripple temperature sensor 57 is supported by the support member 52 at a position on the upstream side of the sheet transport direction D1 with respect to the fixing position P1 in contact with the inner peripheral surface of the sliding member 53. ing. In this case, it is conceivable that the ripple temperature sensor 57 is a thermistor.

As will be described later, the ripple temperature sensor 57 is used to measure the temperature unevenness generated in the sliding member 53 in the slip determination process.

When the sliding member 53 rotates, the portion of the sliding member 53 along the nip Np1 receives an external force in the sheet transport direction D1. By arranging the ripple temperature sensor 57 at the position shown in FIG. 2, the portion of the sliding member 53 facing the ripple temperature sensor 57 is moved toward the inside of the sliding member 53 by the external force. Therefore, the fixing device 48 does not require a mechanism for urging the sliding member 53 to the ripple temperature sensor 57.

Further, in the present embodiment, the plurality of processing modules realized by the CPU 81 executing the computer program further include a slip determination unit 8e. The temperature control unit 8b, the transfer control unit 8c, and the slip determination unit 8e execute the slip determination process.

The temperature control unit 8b, the transport control unit 8c, and the slip determination unit 8e that execute the slip determination process form a part of the fixing device 48.

[Slip judgment processing]
The slip determination unit 8e starts the slip determination process when a predetermined investigation start condition is satisfied. For example, the survey start condition includes the first start condition and the second start condition shown below.

The first start condition is a condition that a predetermined slip determination start operation has been performed on the operation device 801.

The second start condition is a condition that a predetermined time has elapsed since the previous slip determination process was executed and the job of the print process is not accepted.

In the following description, the temperature measured by the ripple temperature sensor 57 is referred to as a ripple measurement temperature.

In the slip determination process, first, with the pressurizing roller 6 stopped, the temperature control unit 8b operates the heater 51 by feeding the heater power supply circuit 50 to the heater 51. As a result, the heater 51 heats only a part of the sliding member 53 in the circumferential direction. Therefore, only a part of the sliding member 53 in the circumferential direction becomes hot, and the sliding member 53 causes temperature unevenness.

After that, when the predetermined ripple measurement start condition is satisfied, the transfer control unit 8c rotates the pressurizing roller 6 at a constant speed by operating the motor 60 through the motor drive circuit 61. For example, the ripple measurement start condition may be the first measurement start condition or the second measurement start condition shown below.

The first measurement start condition is a condition that the measurement temperature of the fixing temperature sensor 56 reaches a predetermined reference temperature. The reference temperature is a temperature sufficiently higher than the temperature around the fixing device 48.

For example, it is conceivable that the reference temperature is in the range from the target temperature set when the sheet 9 passes through the fixing position P1 to a temperature about 50 degrees lower than the target temperature.

The second measurement start condition is a condition that a predetermined time has elapsed since the heater 51 was operated.

When the pressurizing roller 6 rotates at a constant speed due to the establishment of the ripple measurement start condition, the sliding member 53 is driven to rotate, and the local high temperature portion of the sliding member 53 periodically passes through the position of the ripple temperature sensor 57. To do.

Therefore, as shown in FIG. 4, the ripple measurement temperature fluctuates periodically in synchronization with the passage of the local high temperature portion. The graph of FIG. 4 shows a change in the ripple measurement temperature when the heater 51 continuously operates even when the pressurizing roller 6 is rotating due to the establishment of the ripple measurement start condition.

It is also conceivable that the temperature control unit 8b stops the power supply to the heater 51 when the pressurizing roller 6 is rotating due to the establishment of the ripple measurement start condition. In the present embodiment, the temperature control unit 8b and the transfer control unit 8c operate the heater 51 with the pressurizing roller 6 stopped, and then operate the motor 60 to rotate the pressurizing roller 6 at a constant speed. This is an example of a control unit.

Then, the slip determination unit 8e detects the peaks Pk1 and Pk2 of the ripple measurement temperature when the pressurizing roller 6 is rotating at a constant speed. The peaks Pk1 and Pk2 of the ripple measurement temperature include the top peak Pk1 and the bottom peak Pk2 of the ripple measurement temperature.

The top peak Pk1 is generated when the local high temperature portion of the sliding member 53 passes the position of the ripple temperature sensor 57, and the bottom peak Pk2 is the portion of the sliding member 53 farthest from the local high temperature portion. Occurs when passing through the position of the ripple temperature sensor 57.

In the following description, the time interval of the top peak Pk1 is referred to as the first peak time interval Ts1. Further, the time interval between a certain top peak Pk1 and the bottom peak Pk2 that occurs next to the top peak Pk1 and the time interval between a certain bottom peak Pk2 and the top peak Pk1 that occurs next to the bottom peak Pk2. It is referred to as the second peak time interval Ts2.

The first peak time interval Ts1 is the time required for the sliding member 53 to make one rotation. The second peak time interval Ts2 is the time required for the sliding member 53 to rotate half a turn.

The slip determination unit 8e derives the actual peak period based on the first peak time interval Ts1 or the second peak time interval Ts2. For example, the slip determination unit 8e derives a representative value of a plurality of first peak time intervals Ts1 or a representative value of a plurality of second peak time intervals Ts2 as the actual peak period. The representative value is an average value, a median value, or the like.

The actual peak cycle is an example of the time interval of the peak of the measured temperature of the ripple temperature sensor 57 when the pressurizing roller 6 is rotating at a constant speed.

Further, the slip determination unit 8e determines the slip occurrence status of the pressure roller 6 with respect to the sliding member 53 based on the actual peak period.

Specifically, the slip determination unit 8e determines that the slip of the pressure roller 6 has not occurred when the actual peak period is within a predetermined reference range, and the actual peak period is the said. When it deviates from the reference range, it is determined that the slip of the pressure roller 6 has occurred.

Here, when the sliding member 53 rotates at the same peripheral speed as the peripheral speed of the pressure roller 6 rotating at a constant speed, the time required for the sliding member 53 to make one rotation is defined as the reference rotation time. Refer to.

When the actual peak period is a representative value of a plurality of first peak time intervals Ts1, the reference range is a permissible error range based on the reference rotation time.

On the other hand, when the actual peak period is a representative value of a plurality of second peak time intervals Ts2, the reference range is a permissible error range based on half the time of the reference rotation time.

The slip determination unit 8e executes a predetermined notification process when it is determined that the slip of the pressure roller 6 has occurred.

For example, the notification process is a process of displaying a message prompting the replacement or replacement of the sliding member 53 on the display device 802.

Further, the slip determination unit 8e stores the determination result of the slip occurrence status of the pressurizing roller 6 and the determination record information including the information on the date and time when the determination result is obtained in the secondary storage device 83.

The determination record information is used for determining the elapsed time since the previous slip determination process was performed, for example, when determining the success or failure of the second start condition.

Further, when the control device 8 is restarted after the energization is stopped or the state is shifted to the hibernation state, the slip determination unit 8e refers to the determination record information. Then, the slip determination unit 8e executes the notification process when the determination record information indicates the occurrence of the slip.

In the present embodiment, the fixing device 48 can determine the slip occurrence state of the pressure roller 6 with respect to the sliding member 53 only by adding one ripple temperature sensor 57.

[First application example]
Hereinafter, a first application example of the fixing device 48 will be described.

In this application example, the ripple temperature sensor 57 also serves as the fixing temperature sensor 56. As described above, the fixing temperature sensor 56 is a sensor that measures the temperature used for feedback control of the amount of feed to the heater 51 based on the comparison with the target temperature when the sheet 9 passes through the fixing position P1.

When this application example is adopted, it is not necessary to add a temperature sensor to determine the slip occurrence status.

[Second application example]
Hereinafter, a second application example of the fixing device 48 will be described.

In this application example, the ripple temperature sensor 57 is a non-contact temperature sensor. In this case, the ripple temperature sensor 57 may be arranged inside or outside the sliding member 53. For example, the thermopile may be adopted as the ripple temperature sensor 57.

When this application example is adopted, the same effect as when the fixing device 48 is adopted can be obtained.

[Third application example]
Hereinafter, a third application example of the fixing device 48 will be described. In this application example, the ripple temperature sensor 57 is arranged outside the sliding member 53 and is in contact with the outer peripheral surface of the sliding member 53.

Further, in the present application example, the fixing device 48 includes an elastic member that elastically biases the ripple temperature sensor 57 toward the sliding member 53 and the support member 52 inside the sliding member 53. The elastic member is, for example, a spring.

In this application example, the ripple temperature sensor 57 sandwiches a part of the sliding member 53 with the support member 52 by the urging force of the elastic member. As a result, the ripple temperature sensor 57 can measure the temperature of the sliding member 53.

When this application example is adopted, the same effect as when the fixing device 48 is adopted can be obtained.

1: Main body 2: Seat storage 3: Sheet transfer device 4: Image drawing device 5: Heating device 6: Pressurized roller 8: Control device 8a: Main control unit 8b: Temperature control unit 8c: Transfer control unit 8d: Print Control unit 8e: Slip determination unit 9: Sheet 10: Image forming device 30: Sheet sending device 31: Conveying roller pair 40: Printing device 41: Photoreceptor 42: Charging device 43: Developing device 45: Drum cleaning device 46: Optical scanning Device 47: Transfer device 48: Fixing device 50: Heater feeding circuit 51: Heater 52: Support member 53: Sliding member 54: Lubricant 55: Guide member 55a: Standing part 56: Fixing temperature sensor 57: Ripple temperature sensor 60: Motor 61: Motor drive circuit 81: CPU
82: RAM
83: Secondary storage device 84: Signal interface 101: Discharge tray 300: Transport path 471: Intermediate transfer belt 472: Belt transfer device 473: Sheet transfer device 474: Belt cleaning device 801: Operating device 802: Display device D1: Sheet transfer Direction D2: Width direction Np1: Nip P1: Fixing position Pk1: Top peak Pk2: Bottom peak Ts1: First peak time interval Ts2: Second peak time interval

Claims (6)

A fixing device for fixing the toner image to the sheet by heating and pressurizing the toner image on the sheet at the fixing position of the sheet transport path.
A heater arranged along the width direction orthogonal to the sheet transport direction at the fixing position, and
A tubular member that includes the heater, and is rotatably supported, and by rotating, the inner peripheral surface coated with the lubricant slides with respect to the surface of the heater along the sheet transport direction. Members and
A pressurizing member that is rotatably supported and urged toward the heater to form a nip between the sliding member and the sheet through which the sheet passes.
A drive device that rotationally drives the sliding member,
A temperature sensor that measures the temperature of the sliding member,
A control unit that rotates the pressurizing member at a constant speed by operating the driving device after operating the heater in a state where the pressurizing member is stopped.
Fixing including a slip determination unit for determining a slip occurrence state of the pressurizing member with respect to the sliding member based on the time interval of the peak of the measured temperature of the temperature sensor when the pressurizing member is rotating. apparatus. A support member disposed inside the sliding member and supporting the heater and the temperature sensor is further provided.
The first aspect of the present invention, wherein the temperature sensor is supported by the support member at a position upstream of the fixing position in the sheet transport direction and in contact with the inner peripheral surface of the sliding member. Fixing device. When the slip determination unit determines that the pressurizing member has not slipped when the peak time interval is within a predetermined reference range, and the peak time interval deviates from the reference range. The fixing device according to claim 1 or 2, wherein it is determined that the pressurizing member has slipped. The fixing device according to claim 3, wherein the slip determination unit executes a predetermined notification process when it is determined that the pressurizing member has slipped. A 1 to 4 claim, wherein the temperature sensor also serves as a sensor for measuring a temperature used for feedback control of an amount of power supplied to the heater based on a comparison with a target temperature when the sheet passes through the fixing position. The fixing device according to any one of the above items. A transfer device that transfers the toner image to the sheet,
The fixing device according to any one of claims 1 to 5, wherein the toner image is fixed on the sheet.
An image forming apparatus comprising.