JP7451347B2 - Temperature control device and image forming device - Google Patents

Description

Embodiments of the present invention relate to a temperature control device and an image forming device.

The image forming apparatus includes a fixing device that fixes a toner image on a printing medium by applying heat and pressure to the printing medium. The fixing device includes a fixing rotating body (heat roller), a pressure member (press roller), a heating member (such as a lamp or an IH heater), and a temperature sensor. The temperature sensor detects the temperature of the surface of the heat roller.

A controller that controls the fixing device controls the surface temperature of the heat roller to a target value by increasing or decreasing the amount of electricity supplied to the heater based on the detection signal of the temperature sensor (temperature sensor signal).

If a deviation (or time lag) occurs between the temperature detected by the temperature sensor and the surface temperature of the heat roller, overshoot, temperature ripple, etc. may occur. Therefore, in order to prevent the occurrence of overshoot and temperature ripple, a temperature sensor with good responsiveness (for example, a thermopile, etc.) is required. However, a temperature sensor with good responsiveness has a problem in that it is expensive.

Japanese Patent Application Publication No. 2002-116658

An object of the present invention is to provide a temperature control device and an image forming apparatus that can prevent overshoot and temperature ripples from occurring.

A temperature control device according to one embodiment is a temperature control device that controls the temperature of a temperature-controlled object to which heat is propagated from the heater by supplying power to the heater, and includes a temperature estimation section and a high frequency component extraction section. , a counting section, an adding section, and a control signal generating section. The temperature estimator estimates the temperature of the temperature controlled object based on energization of the heater. The high frequency component extractor extracts a high frequency component of the temperature estimation result. The counting unit counts the number of times the heater is turned on based on energization of the heater. The addition unit sets a coefficient for adjusting the high frequency component to be added to the temperature detection result of the temperature control target by the temperature sensor based on the number of lighting times, and adds the result of multiplying the high frequency component by the coefficient to the temperature detection result. Calculate the corrected temperature value added to. The control signal generation unit outputs an energization pulse for controlling power supplied to the heater based on the corrected temperature value.

FIG. 1 is a diagram for explaining an example of the configuration of an image forming apparatus according to an embodiment. FIG. 2 is a diagram for explaining an example of the configuration of a heater energization control circuit according to an embodiment. FIG. 3 is a diagram for explaining an example of the operation of the heater energization control circuit according to one embodiment. FIG. 4 is a diagram for explaining an example of the operation of the heater energization control circuit according to one embodiment. FIG. 5 is a diagram for explaining an example of the operation of the heater energization control circuit according to one embodiment. FIG. 6 is a diagram for explaining an example of the operation of the heater energization control circuit according to one embodiment. FIG. 7 is a flowchart illustrating coefficient setting processing of the heater energization control circuit according to one embodiment. FIG. 8 is a diagram illustrating an example of setting coefficients in coefficient setting processing of the heater energization control circuit according to an embodiment.

Hereinafter, a temperature control device and an image forming device according to one embodiment will be described with reference to the drawings.
FIG. 1 is an explanatory diagram for explaining a configuration example of an image forming apparatus 1 according to an embodiment.

The image forming apparatus 1 is, for example, a multi-function printer (MFP) that performs various processes such as image formation while conveying a recording medium such as a print medium. The image forming apparatus 1 is, for example, a solid-state scanning type printer (for example, an LED printer) that scans an LED array that performs various processes such as image formation while conveying a recording medium such as a print medium.

For example, the image forming apparatus 1 is configured to receive toner from a toner cartridge and form an image on a print medium using the received toner. The toner may be a single color toner, or may be a color toner such as cyan, magenta, yellow, and black. Further, the toner may be a decolorable toner that decolorizes when heat is applied.

As shown in FIG. 1, the image forming apparatus 1 includes a housing 11, a communication interface 12, a system controller 13, a heater energization control circuit 14, a display section 15, an operation interface 16, a plurality of paper trays 17, and a paper output tray 18. , a transport section 19, an image forming section 20, and a fixing device 21.

The housing 11 is the main body of the image forming apparatus 1 . The housing 11 includes a communication interface 12, a system controller 13, a heater energization control circuit 14, a display section 15, an operation interface 16, a plurality of paper trays 17, a paper output tray 18, a transport section 19, an image forming section 20, and a fixing device. Accommodates 21 people.

First, the configuration of the control system of the image forming apparatus 1 will be described.
The communication interface 12 is an interface for communicating with other devices. The communication interface 12 is used, for example, to communicate with a host device (external device). The communication interface 12 is configured as, for example, a LAN connector. Further, the communication interface 12 may perform wireless communication with other devices according to a standard such as Bluetooth (registered trademark) or Wi-fi (registered trademark).

A system controller 13 controls the image forming apparatus 1 . The system controller 13 includes, for example, a processor 22 and a memory 23.

The processor 22 is an arithmetic element that performs arithmetic processing. The processor 22 is, for example, a CPU. The processor 22 performs various processes based on data such as programs stored in the memory 23. The processor 22 functions as a control unit that can execute various operations by executing programs stored in the memory 23.

The memory 23 is a storage medium that stores programs and data used in the programs. The memory 23 also functions as a working memory. That is, the memory 23 temporarily stores data being processed by the processor 22, programs executed by the processor 22, and the like.

The processor 22 performs various information processing by executing programs stored in the memory 23. For example, the processor 22 generates a print job based on an image obtained from an external device via the communication interface 12. The processor 22 stores the generated print job in the memory 23.

The print job includes image data indicating an image to be formed on the print medium P. The image data may be data for forming an image on one print medium P, or may be data for forming an image on a plurality of print media P. Furthermore, the print job includes information indicating whether it is color printing or monochrome printing. Furthermore, the print job may include information such as the number of copies to be printed (number of page sets) and the number of sheets to be printed per copy (number of pages).

Furthermore, the processor 22 generates print control information for controlling the operations of the transport section 19, image forming section 20, and fixing device 21 based on the generated print job. The print control information includes information indicating the timing of paper passing. The processor 22 supplies print control information to the heater energization control circuit 14 .

Furthermore, the processor 22 functions as a controller (engine controller) that controls the operations of the transport section 19 and the image forming section 20 by executing a program stored in the memory 23 . That is, the processor 22 controls the transport of the print medium P by the transport section 19, the formation of an image on the print medium P by the image forming section 20, and the like.

Note that the image forming apparatus 1 may be configured to include an engine controller separately from the system controller 13. In this case, the engine controller controls the transportation of the printing medium P by the transportation section 19, the formation of an image on the printing medium P by the image forming section 20, and the like. Further, in this case, the system controller 13 supplies the engine controller with information necessary for control in the engine controller.

The image forming apparatus 1 also includes a power conversion circuit (not shown) that supplies DC voltage to various components within the image forming apparatus 1 using the AC voltage of the AC power supply AC. The power conversion circuit supplies the system controller 13 with DC voltage necessary for the operation of the processor 22 and memory 23. Further, the power conversion circuit supplies the image forming section 20 with a DC voltage necessary for image formation. Further, the power conversion circuit supplies the transport unit 19 with a DC voltage necessary for transporting the print medium. Further, the power conversion circuit supplies a DC voltage for driving the heater of the fixing device 21 to the heater energization control circuit 14 .

The heater energization control circuit 14 is a temperature control device (temperature control section) that controls energization to the heater of the fixing device 21, which will be described later. The heater energization control circuit 14 generates energization power PC for energizing the heater of the fixing device 21 and supplies it to the heater of the fixing device 21 . A detailed explanation of the heater energization control circuit 14 will be given later.

The display unit 15 includes a display that displays a screen according to a video signal input from the system controller 13 or a display control unit such as a graphic controller (not shown). For example, screens for various settings of the image forming apparatus 1 are displayed on the display of the display unit 15.

The operation interface 16 is connected to an operation member (not shown). The operation interface 16 supplies an operation signal to the system controller 13 according to the operation of the operation member. The operation member is, for example, a touch sensor, a numeric keypad, a power key, a paper feed key, various function keys, or a keyboard. The touch sensor acquires information indicating a specified position within a certain area. The touch sensor inputs a signal indicating a touched position on the screen displayed on the display section 15 to the system controller 13 by being configured as a touch panel integrally with the display section 15 .

Each of the plurality of paper trays 17 is a cassette that accommodates print media P. The paper tray 17 is configured to be able to supply the print medium P from outside the housing 11 . For example, the paper tray 17 is configured to be able to be pulled out from the housing 11.

The paper discharge tray 18 is a tray that supports the print medium P discharged from the image forming apparatus 1 .

Next, a configuration for conveying the print medium P of the image forming apparatus 1 will be described.
The transport unit 19 is a mechanism that transports the print medium P within the image forming apparatus 1 . As shown in FIG. 1, the transport section 19 includes a plurality of transport paths. For example, the transport section 19 includes a paper feed transport path 31 and a paper discharge transport path 32.

The paper feed conveyance path 31 and the paper discharge conveyance path 32 each include a plurality of motors, a plurality of rollers, and a plurality of guides (not shown). The plurality of motors rotate the shafts under the control of the system controller 13, thereby rotating rollers that are linked to the rotation of the shafts. The plurality of rollers move the print medium P by rotating. The plurality of guides control the conveyance direction of the print medium P.

The paper feed conveyance path 31 takes in the print medium P from the paper tray 17 and supplies the taken in print medium P to the image forming section 20 . The paper feed conveyance path 31 includes pickup rollers 33 corresponding to each paper tray. Each pickup roller 33 takes in the print medium P from the paper tray 17 into the paper feed conveyance path 31, respectively.

The discharge conveyance path 32 is a conveyance path through which the print medium P on which an image is formed is discharged from the housing 11. The print medium P discharged through the paper discharge conveyance path 32 is supported by the paper discharge tray 18 .

Next, the image forming section 20 will be explained.
The image forming section 20 is configured to form an image on the print medium P. Specifically, the image forming unit 20 forms an image on the print medium P based on the print job generated by the processor 22.

The image forming section 20 includes a plurality of process units 41, a plurality of exposure devices 42, and a transfer mechanism 43. The image forming section 20 includes an exposure device 42 for each process unit 41. Note that since the plurality of process units 41 and the plurality of exposure devices 42 each have the same configuration, one process unit 41 and one exposure device 42 will be described respectively.

First, the process unit 41 will be explained.
The process unit 41 is configured to form a toner image. For example, a plurality of process units 41 are provided for each type of toner. For example, the plurality of process units 41 respectively correspond to color toners such as cyan, magenta, yellow, and black. Specifically, each process unit 41 is connected to a toner cartridge containing toner of a different color.

The toner cartridge includes a toner container and a toner delivery mechanism. The toner storage container is a container that stores toner. The toner delivery mechanism is a mechanism that includes a screw or the like that delivers the toner in the toner storage container.

The process unit 41 includes a photosensitive drum 51, a charger 52, and a developing device 53.
The photosensitive drum 51 is a photosensitive body that includes a cylindrical drum and a photosensitive layer formed on the outer peripheral surface of the drum. The photosensitive drum 51 is rotated at a constant speed by a drive mechanism (not shown).

The charger 52 uniformly charges the surface of the photosensitive drum 51. For example, the charger 52 charges the photosensitive drum 51 to a uniform negative potential (contrast potential) by applying a voltage (developing bias voltage) to the photosensitive drum 51 using a charging roller. The charging roller rotates as the photosensitive drum 51 rotates while applying a predetermined pressure to the photosensitive drum 51.

The developing device 53 is a device that attaches toner to the photosensitive drum 51. The developing device 53 includes a developer container, a stirring mechanism, a developing roller, a doctor blade, an auto toner control (ATC) sensor, and the like.

The developer container is a container that receives and stores the toner sent out from the toner cartridge. A carrier is stored in the developer container in advance. The toner sent out from the toner cartridge is stirred with the carrier by the stirring mechanism, thereby forming a developer in which the toner and the carrier are mixed. The carrier is housed in a developer container when the developing device 53 is manufactured.

The developing roller causes developer to adhere to the surface by rotating within the developer container. The doctor blade is a member disposed at a predetermined distance from the surface of the developing roller. The doctor blade removes a portion of the developer attached to the surface of the rotating developing roller. As a result, a layer of developer is formed on the surface of the developing roller with a thickness corresponding to the distance between the doctor blade and the surface of the developing roller.

The ATC sensor is, for example, a magnetic flux sensor that has a coil and detects a voltage value generated in the coil. The detection voltage of the ATC sensor changes depending on the density of magnetic flux from the toner in the developer container. That is, the system controller 13 determines the concentration ratio of the toner remaining in the developer container to the carrier (toner concentration ratio) based on the detected voltage of the ATC sensor. Based on the toner concentration ratio, the system controller 13 operates a motor (not shown) that drives a toner cartridge delivery mechanism, and sends the toner from the toner cartridge to the developer container of the developing device 53.

Next, the exposure device 42 will be explained.
The exposure device 42 includes a plurality of light emitting elements. The exposure device 42 forms a latent image on the photosensitive drum 51 by irradiating the charged photosensitive drum 51 with light from a light emitting element. The light emitting element is, for example, a light emitting diode (LED). One light emitting element is configured to irradiate light to one point on the photosensitive drum 51. The plurality of light emitting elements are arranged in the main scanning direction, which is a direction parallel to the rotation axis of the photosensitive drum 51.

The exposure device 42 forms a one-line latent image on the photosensitive drum 51 by irradiating light onto the photosensitive drum 51 using a plurality of light emitting elements arranged in the main scanning direction. Further, the exposure device 42 forms a plurality of lines of latent images by continuously irradiating the rotating photosensitive drum 51 with light.

In the above configuration, when the surface of the photosensitive drum 51 charged by the charging charger 52 is irradiated with light from the exposure device 42, an electrostatic latent image is formed. When the developer layer formed on the surface of the developing roller approaches the surface of the photosensitive drum 51, toner contained in the developer adheres to the latent image formed on the surface of the photosensitive drum 51. As a result, a toner image is formed on the surface of the photosensitive drum 51.

Next, the transfer mechanism 43 will be explained.
The transfer mechanism 43 is configured to transfer the toner image formed on the surface of the photosensitive drum 51 onto the print medium P.

The transfer mechanism 43 includes, for example, a primary transfer belt 61, a secondary transfer opposing roller 62, a plurality of primary transfer rollers 63, and a secondary transfer roller 64.

The primary transfer belt 61 is an endless belt wrapped around a secondary transfer opposing roller 62 and a plurality of wrapping rollers. The primary transfer belt 61 has an inner surface (inner circumferential surface) in contact with the secondary transfer opposing roller 62 and the plurality of wrapping rollers, and an outer surface (outer circumferential surface) that faces the photosensitive drum 51 of the process unit 41. .

The secondary transfer opposing roller 62 is rotated by a motor (not shown). The secondary transfer opposing roller 62 rotates to convey the primary transfer belt 61 in a predetermined conveyance direction. The plurality of winding rollers are configured to be freely rotatable. The plurality of winding rollers rotate according to the movement of the primary transfer belt 61 by the secondary transfer opposing roller 62.

The plurality of primary transfer rollers 63 are configured to bring the primary transfer belt 61 into contact with the photosensitive drum 51 of the process unit 41 . The plurality of primary transfer rollers 63 are provided to correspond to the photosensitive drums 51 of the plurality of process units 41. Specifically, the plurality of primary transfer rollers 63 are provided at positions facing the photosensitive drums 51 of the corresponding process units 41 with the primary transfer belt 61 in between. The primary transfer roller 63 contacts the inner peripheral surface of the primary transfer belt 61 and displaces the primary transfer belt 61 toward the photosensitive drum 51 . Thereby, the primary transfer roller 63 brings the outer peripheral surface of the primary transfer belt 61 into contact with the photosensitive drum 51.

The secondary transfer roller 64 is provided at a position facing the primary transfer belt 61. The secondary transfer roller 64 contacts the outer peripheral surface of the primary transfer belt 61 and applies pressure. As a result, a transfer nip is formed in which the secondary transfer roller 64 and the outer peripheral surface of the primary transfer belt 61 come into close contact with each other. When the print medium P passes through the transfer nip, the secondary transfer roller 64 presses the print medium P passing through the transfer nip against the outer peripheral surface of the primary transfer belt 61 .

The secondary transfer roller 64 and the secondary transfer opposing roller 62 rotate to convey the print medium P supplied from the paper feed conveyance path 31 while sandwiching the print medium P therebetween. As a result, the print medium P passes through the transfer nip.

In the above configuration, when the outer circumferential surface of the primary transfer belt 61 comes into contact with the photosensitive drum 51, the toner image formed on the surface of the photosensitive drum is transferred to the outer circumferential surface of the primary transfer belt 61. When the image forming section 20 includes a plurality of process units 41 , the primary transfer belt 61 receives toner images from the photosensitive drums 51 of the plurality of process units 41 . The toner image transferred to the outer peripheral surface of the primary transfer belt 61 is conveyed by the primary transfer belt 61 to a transfer nip where the secondary transfer roller 64 and the outer peripheral surface of the primary transfer belt 61 are in close contact. When the printing medium P exists in the transfer nip, the toner image transferred to the outer peripheral surface of the primary transfer belt 61 is transferred to the printing medium P in the transfer nip.

Next, a configuration related to fixing of the image forming apparatus 1 will be described.
The fixing device 21 fixes the toner image onto the print medium P onto which the toner image has been transferred. The fixing device 21 operates under the control of the system controller 13 and the heater energization control circuit 14 . The fixing device 21 includes a fixing rotating body, a pressure member, and a heating member. The heating member fixing rotating body heating member is, for example, the heat roller 71. Further, the pressure member is, for example, a press roller 72. The heating member is, for example, a heater 73 that heats the heat roller 71. Furthermore, the fixing device 21 includes a temperature sensor (thermal sensor) 74 that detects the temperature of the surface of the heat roller 71. Further, the fixing device 21 includes a voltage detector 75.

The heat roller 71 is a fixing rotating body rotated by a motor (not shown). The heat roller 71 has a hollow metal core and an elastic layer formed on the outer periphery of the core. For example, the diameter φ of the heat roller 71 is 30 mm. For example, the thickness of the core metal is 0.6 mm. The inner side of the core metal of the heat roller 71 is heated by a heater 73 disposed inside the core metal formed in a hollow shape. The heat generated inside the core metal is transferred to the outside surface of the heat roller 71 (ie, the surface of the elastic layer). For example, the heater 73 is composed of a heater lamp divided into two parts. In this example, the heater 73 includes a center lamp that warms the center of the heat roller 71 and side lamps that warm the ends of the heat roller 71. For example, the wattage of the center lamp and side lamps is 600W each. The center lamp and side lamps can be turned on alternately. The heat roller 71 is an example of a temperature controlled object.

The press roller 72 is provided at a position facing the heat roller 71. The press roller 72 has a core made of metal with a predetermined outer diameter, and an elastic layer formed on the outer periphery of the core. For example, the diameter φ of the press roller 72 is 30 mm. The press roller 72 applies pressure to the heat roller 71 by stress applied from a tension member (not shown). For example, the P/R pressurization is configured to be 150N. By applying pressure from the press roller 72 to the heat roller 71, a nip (fixing nip) in which the press roller 72 and the heat roller 71 are in close contact is formed. The press roller 72 is rotated by a motor (not shown). The press roller 72 rotates to move the print medium P that has entered the fixing nip and presses the print medium P against the heat roller 71 .

The heater 73 is a device that generates heat using the energization power PC supplied from the heater energization control circuit 14 . The heater 73 is, for example, a halogen heater. The heater 73 generates heat inside the core metal of the heat roller 71 by energizing the halogen lamp heater, which is a heat source, with the energizing power PC supplied from the heater energization control circuit 14, using electromagnetic waves radiated from the halogen lamp heater. . Furthermore, the heater 73 may be, for example, an IH heater.

The temperature sensor 74 detects the temperature of the air near the surface of the heat roller 71. There may be a plurality of temperature sensors 74. For example, a plurality of temperature sensors 74 may be arranged parallel to the rotation axis of the heat roller 71. Note that the temperature sensor 74 only needs to be provided at a position where it can detect at least a change in the temperature of the heat roller 71. The temperature sensor 74 supplies the heater energization control circuit 14 with a temperature detection signal Td indicating the detection result.

Voltage detector 75 detects the value of the input voltage to heater 73. The voltage detector 75 only needs to be provided at a position where it can detect at least the value of the input voltage to the heater 73. The voltage detector 75 supplies the heater energization control circuit 14 with a voltage detection signal Vd indicating the value of the input voltage.

With the above configuration, the heat roller 71 and the press roller 72 apply heat and pressure to the print medium P passing through the fixing nip. The toner on the print medium P is melted by the heat applied from the heat roller 71 and applied to the surface of the print medium P by the pressure applied by the heat roller 71 and the press roller 72. As a result, the toner image is fixed on the print medium P that has passed through the fixing nip. The print medium P that has passed through the fixing nip is introduced into the paper discharge conveyance path 32 and discharged to the outside of the casing 11 .

Next, the heater energization control circuit 14 will be explained.
The heater energization control circuit 14 controls the energization of the heater 73 of the fixing device 21 . The heater energization control circuit 14 generates energization power PC for energizing the heater 73 of the fixing device 21 and supplies it to the heater 73 of the fixing device 21 .

As shown in FIG. 2, the heater energization control circuit 14 includes a temperature estimation section 81, an estimation history holding section 82, a high frequency component extraction section 83, a counting section 84, a coefficient addition section 85, a target temperature output section 86, and a difference comparison section. 87, a control signal generation section 88, and a power supply circuit 89. Further, the temperature detection result Td is inputted to the heater energization control circuit 14 from the temperature sensor 74 . A voltage detection signal Vd can be input to the heater energization control circuit 14 from the voltage detector 75 .

The temperature estimation unit 81 performs temperature estimation processing to estimate the temperature of the surface of the heat roller 71. The temperature estimation unit 81 receives a temperature detection result Td from the temperature sensor 74, an estimation history PREV from an estimation history holding unit 82 (described later), and an energization pulse Ps from a control signal generation unit 88 (described later). The temperature estimation unit 81 generates a temperature estimation result EST based on the temperature detection result Td, the estimation history PREV, and the energization pulse Ps. Further, the temperature estimation unit 81 calculates the temperature based on the temperature detection result Td, the estimation history PREV, the energization pulse Ps, and the voltage (rated voltage) supplied to the heater 73 when the energization pulse Ps is on. The configuration may also be such that the estimation result EST is generated. The temperature estimation section 81 outputs the temperature estimation result EST to the estimation history holding section 82 and the high frequency component extraction section 83.

The estimation history holding unit 82 holds a history of temperature estimation results EST. The estimation history holding unit 82 outputs the estimation history PREV, which is the history of the temperature estimation results EST (past temperature estimation results EST), to the temperature estimation unit 81.

The high frequency component extraction unit 83 performs high-pass filter processing to extract high frequency components of the temperature estimation result EST. The high frequency component extractor 83 outputs a high frequency component HPF, which is a signal indicating the extracted high frequency component, to the coefficient adder 85.

The counting unit 84 counts the number of times the heater 73 is turned on based on the energization of the heater 73 . The counting section 84 receives an energizing pulse Ps from a control signal generating section 88, which will be described later. The counting unit 84 counts the number of times the heater 73 is turned on based on the energization pulse Ps, which is an example of energizing the heater 73 . The number of lighting times corresponds to the number of energization pulses Ps. The counting unit 84 counts the number of times the light is turned on every fixed period. For example, the fixed period is one minute, but is not limited to this. The counting section 84 outputs the counted number of lighting times CNT to the coefficient adding section 85.

The coefficient addition unit 85 performs coefficient addition processing that is correction of the temperature detection result Td. The coefficient adder 85 receives the temperature detection result Td from the temperature sensor 74 , the high frequency component HPF from the high frequency component extractor 83 , and the number of times of lighting CNT from the counter 84 . The coefficient adder 85 sets a coefficient K based on the number of times of lighting CNT. The coefficient K is a value for adjusting the high frequency component HPF to be added to the temperature detection result Td of the heat roller 71 by the temperature sensor 74. The coefficient K can also be said to be the ratio of the value of the high frequency component HPF to be added to the temperature detection result Td. The coefficient adding section 85 sets the coefficient K based on the number of times of lighting CNT for each fixed period counted by the counting section 84. An example of setting the coefficient K will be described later. The coefficient addition unit 85 corrects the temperature detection result Td based on the high frequency component HPF. Specifically, the coefficient addition unit 85 calculates a corrected temperature value WAE by adding the result of multiplying the high frequency component HPF by the coefficient K to the temperature detection result Td. That is, the coefficient addition unit 85 calculates the corrected temperature value WAE=temperature detection result Td+K×high frequency component HPF. The coefficient addition section 85 outputs the corrected temperature value WAE to the difference comparison section 87. The coefficient adder 85 is an example of an adder.

The target temperature output section 86 outputs a preset target temperature TGT to the difference comparison section 87.

The difference comparison unit 87 performs difference calculation processing. The difference comparison section 87 calculates the difference DIF between the target temperature TGT from the target temperature output section 86 and the corrected temperature value WAE from the coefficient addition section 85, and outputs it to the control signal generation section 88.

The control signal generation unit 88 generates an energization pulse Ps, which is a pulse signal for controlling energization to the heater 73, based on the difference DIF. The control signal generation section 88 outputs the energization pulse Ps to the power supply circuit 89, the temperature estimation section 81, and the counting section 84. That is, the control signal generation unit 88 outputs the energization pulse Ps for controlling the power supplied to the heater 73 based on the corrected temperature value WAE.

The power supply circuit 89 supplies energization power PC to the heater 73 based on the energization pulse Ps. The power supply circuit 89 energizes the heater 73 of the fixing device 21 using a DC voltage supplied from a power conversion circuit (not shown). The power supply circuit 89 supplies energizing power PC to the heater 73 by, for example, switching between a state in which the DC voltage from the power conversion circuit is supplied to the heater 73 and a state in which it is not supplied, based on the energization pulse Ps. That is, the power supply circuit 89 varies the time period during which the heater 73 of the fixing device 21 is energized in accordance with the energization pulse Ps.

Note that the power supply circuit 89 may be configured integrally with the fixing device 21. That is, the heater energization control circuit 14 may be configured to supply the energization pulse Ps to the power supply circuit of the heater 73 of the fixing device 21 instead of supplying the energization pulse Ps to the heater 73 of the energization power PC.

As described above, the heater energization control circuit 14 adjusts the amount of power supplied to the heater 73 of the fixing device 21 based on the temperature detection result Td, the temperature estimation history PREV, and the energization pulse Ps. Thereby, the heater energization control circuit 14 controls the surface temperature of the heat roller 71 heated by the heater 73. Such control is called Weighted Average control with Estimate temperature (WAE control). Note that the heater energization control circuit 14 includes a temperature estimation section 81, an estimation history holding section 82, a high frequency component extraction section 83, a counting section 84, a coefficient addition section 85, a target temperature output section 86, a difference comparison section 87, and a control signal generation section. Each of 88 may be configured by an electric circuit or may be configured by software.

The WAE control will be explained in detail below.
FIG. 3 is a flowchart for explaining WAE control. 4 and 5 are explanatory diagrams for explaining each signal in WAE control. The horizontal axis in FIGS. 4 and 5 indicates time. The vertical axis in FIGS. 4 and 5 indicates temperature.

The heater energization control circuit 14 sets various initial values (ACT11). For example, the heater energization control circuit 14 sets the target temperature TGT of the target temperature output section 86 based on a signal from the system controller 13.

The temperature estimation unit 81 of the heater energization control circuit 14 obtains the temperature detection result Td from the temperature sensor 74, the estimation history PREV from the estimation history holding unit 82, and the energization pulse Ps from the control signal generation unit 88 (ACT12).

As shown in FIG. 4, there is a difference between the temperature detection result Td and the actual surface temperature of the heat roller 71. The surface temperature of the heat roller 71 changes in small cycles because heating is performed intermittently by the heater 73. On the other hand, the temperature sensor 74 may have poor responsiveness to temperature changes depending on its own heat capacity and the characteristics of the temperature-sensitive material. In particular, cheaper temperature sensors tend to have poorer responsiveness. As a result, the temperature detection result Td cannot accurately track the actual surface temperature of the heat roller 71. That is, the temperature detection result Td is detected by the temperature sensor 74 with a delay with respect to the surface temperature of the heat roller 71. Further, the temperature detection result Td is detected by the temperature sensor 74 in a smoothed state without reproducing fine changes in the surface temperature of the heat roller 71.

The temperature estimation unit 81 performs temperature estimation processing (ACT13). That is, the temperature estimation unit 81 generates the temperature estimation result EST based on the temperature detection result Td, the estimation history PREV, and the energization pulse Ps. The temperature estimation section 81 outputs the temperature estimation result EST to the high frequency component extraction section 83 and the estimation history holding section 82.

The transfer of heat can be equivalently expressed by the CR time constant of an electric circuit. The heat capacity is replaced by a capacitor C. The resistance of heat transfer is replaced by a resistance R. The heat source is replaced by a DC voltage source. The temperature estimation unit 81 estimates the amount of heat given to the heat roller 71 based on the CR circuit in which the values of each element are set in advance based on the amount of electricity applied to the heater 73 and the heat capacity of the heat roller 71. . The temperature estimation unit 81 estimates the surface temperature of the heat roller 71 based on the amount of heat given to the heat roller 71, the temperature detection result Td, and the estimation history PREV, and outputs the temperature estimation result EST.

The temperature estimation unit 81 is repeatedly energized/cut off from the DC voltage source based on the energization pulse Ps, and the CR circuit operates according to the input voltage pulse to generate an output voltage. Thereby, it is possible to estimate the heat propagated to the surface of the heat roller 71, which is the object of temperature control.

Note that the heat from the heat roller 71 flows out to the external environment via the space inside the fixing device 21 (outside the heat roller 71). For this reason, the temperature estimation section 81 further includes a CR circuit for estimating the outflow of heat from the heat roller 71 to the external environment. Further, the temperature estimating unit 81 may further include a CR circuit for estimating the amount of heat flowing from the heat roller 71 into the space within the fixing device 21 .

As shown in FIG. 4, the temperature estimation result EST appropriately follows the change in the actual surface temperature of the heat roller 71. However, since the temperature estimation result EST is a simulation result, the absolute value may differ from the actual surface temperature of the heat roller due to differences in conditions.

The high frequency component extraction unit 83 performs high-pass filter processing to extract the high frequency component of the temperature estimation result EST (ACT14). As shown in FIG. 4, the high frequency component HPF, which is a signal indicating the high frequency component of the temperature estimation result EST, appropriately follows the change in the actual surface temperature of the heat roller 71.

The coefficient addition unit 85 performs coefficient addition processing, which is correction of the temperature detection result Td (ACT15). The coefficient adder 85 calculates a corrected temperature value WAE by adding the result of multiplying the high frequency component HPF by the coefficient K to the temperature detection result Td. That is, the coefficient addition unit 85 adjusts the value of the high frequency component HPF to be added to the temperature detection result Td by the coefficient K, and calculates the corrected temperature value WAE.

For example, when the coefficient is 1, the coefficient adding section 85 directly adds the high frequency component HPF to the temperature detection result Td. Further, for example, when the coefficient is 0.1, the coefficient adding section 85 adds a value of 1/10 of the high frequency component HPF to the temperature detection result Td. In this case, the effect of the high frequency component HPF is almost eliminated, and the temperature detection result becomes close to Td. Further, for example, when the coefficient is 1 or more, the effect of the high frequency component HPF can be expressed more strongly.

FIG. 5 is an explanatory diagram for explaining an example of the actual surface temperature of the heat roller 71, the temperature detection result Td, and the corrected temperature value WAE. In the WAE control, minute changes in the surface temperature of the heat roller 71 are estimated based on the temperature detection result Td and the high frequency component HPF of the temperature estimation result EST. Therefore, as shown in FIG. 5, the corrected temperature value WAE is a value that appropriately follows the surface temperature of the heat roller 71.

The difference comparison section 87 calculates the difference DIF between the target temperature TGT from the target temperature output section 86 and the corrected temperature value WAE from the coefficient addition section 85, and outputs it to the control signal generation section 88 (ACT16).

The control signal generation unit 88 generates the energization pulse Ps based on the difference DIF. The control signal generation unit 88 outputs the energization pulse Ps to the power supply circuit 89 and the temperature estimation unit 81 (ACT17). The power supply circuit 89 supplies energization power PC to the heater 73 based on the energization pulse Ps.

The relationship between the target temperature TGT and the corrected temperature value WAE appears in the difference DIF. For example, if the corrected temperature value WAE>target temperature TGT, by narrowing the width of the energizing pulse Ps or reducing its frequency, the amount of energization to the heater 73 is reduced, and the heat roller surface temperature is Go down. In addition, when the corrected temperature value WAE<target temperature TGT, the amount of current applied to the heater 73 increases by controlling the width of the energization pulse Ps to widen or increase the frequency, and the surface temperature of the heat roller increases. .

Note that from the difference DIF, it is possible to grasp not only the vertical relationship between the corrected temperature value WAE and the target temperature TGT, but also how far apart they are. For example, when the difference DIF (absolute value thereof) is a large value, the deviation between the corrected temperature value WAE and the target temperature TGT is large, so the above control may be changed significantly. Further, for example, when (the absolute value of) the difference DIF is a small value, the deviation between the corrected temperature value WAE and the target temperature TGT is small, so the above control may be performed slowly.

The processor 22 of the system controller 13 determines whether to end WAE control (ACT18). When the processor 22 determines to continue WAE control, it moves to the process of ACT12. Further, when the processor 22 determines to end the WAE control, it ends the process of FIG. 3 .

As described above, when processing a certain cycle (the relevant cycle), the heater energization control circuit 14 uses the values in the previous cycle (the energization pulse Ps and temperature estimation result EST: estimation history PREV) and the value in the current cycle. WAE control is performed based on the temperature detection result Ts. That is, the heater energization control circuit 14 inherits the value in the next cycle. The heater energization control circuit 14 recalculates the temperature estimation based on the history of previous calculations. Therefore, the heater energization control circuit 14 constantly performs calculations during operation. In the heater energization control circuit 14, the calculation result is held in a memory or the like and reused in the calculation of the next cycle.

FIG. 6 is an explanatory diagram for explaining a processing cycle in the heater energization control circuit 14. As shown in FIG. The horizontal axis in FIG. 6 indicates time. For example, the temperature estimating unit 81 performs temperature estimation processing at time t(n), performs the next temperature estimation processing at t(n+1), which is ahead by dt, and then performs the next temperature estimation processing at t(n+2), which is further advanced by dt. ) performs temperature estimation processing. In this manner, the temperature estimation unit 81 repeatedly performs temperature estimation processing. The temperature estimation unit 81 uses the previous temperature estimation result EST to estimate a new temperature in the temperature estimation process of each cycle.

At time t(n), the temperature detection result Td at time t(n), the energization pulse Ps at the previous time t(n-1), and the temperature estimation result EST( The estimation history PREV) is input to the temperature estimating section 81. The temperature estimation unit 81 performs processing based on the input signal and outputs the temperature estimation result EST at time t(n). The high frequency component extractor 83, the coefficient adder 85, the difference comparator 87, and the control signal generator 88 perform processing based on the input signals and output the energization pulse Ps at time t(n).

At time t(n+1), the temperature detection result Td newly detected at time t(n+1), the energization pulse Ps at time t(n), and the estimation history PREV which is the temperature estimation result EST at time t(n) are The temperature is input to the temperature estimating section 81. The temperature estimation unit 81 performs processing based on the input signal and outputs the temperature estimation result EST at time t(n+1). The high frequency component extraction section 83, the coefficient addition section 85, the difference comparison section 87, and the control signal generation section 88 perform processing based on the input signals and output the energization pulse Ps at time t(n+1).

At time t(n+2), the temperature detection result Td newly detected at time t(n+2), the energization pulse Ps at time t(n+1), and the estimation history PREV which is the temperature estimation result EST at time t(n+1) are The temperature is input to the temperature estimating section 81. The temperature estimation unit 81 performs processing based on the input signal and outputs the temperature estimation result EST at time t(n+2). The high frequency component extraction section 83, the coefficient addition section 85, the difference comparison section 87, and the control signal generation section 88 perform processing based on the input signals and output the energization pulse Ps at time t(n+2).

Note that the above-mentioned time interval dt may be a fixed value or may be configured to be set in the initial value setting of ACT11. For example, the time interval dt is set to 100 [msec].

The coefficient setting process by the coefficient adding section 85 will be described below.
FIG. 7 is a flowchart illustrating the coefficient setting process.

The coefficient addition unit 85 detects the start of the printing operation (ACT21). In ACT21, for example, the coefficient addition unit 85 detects the start of the printing operation based on a signal from the system controller 13 indicating the start of the printing operation.
The coefficient adder 85 sets an initial value to the coefficient K (ACT22). In ACT22, for example, the coefficient addition unit 85 sets the coefficient K to an arbitrary determined initial value. The initial value is the set value of the coefficient K at the time of starting energization to the heater 73 of the fixing device 21, such as at the start of a printing operation. The initial value can be updated as appropriate. For example, the initial value is 0.6 (60%).

The coefficient addition unit 85 obtains the number of lighting times CNT (ACT22). In ACT22, for example, the coefficient addition unit 85 obtains the number of lighting times in a certain period counted by the counting unit 84.
The coefficient adder 85 sets the coefficient K (ACT24). In ACT24, for example, the coefficient adding section 85 sets the coefficient K based on the number of times of lighting in a certain period counted by the counting section 84. An example of setting the coefficient K in ACT24 will be described later.

The coefficient addition unit 85 detects the end of the printing operation (ACT25). In ACT25, for example, the coefficient addition unit 85 detects the end of the printing operation based on a signal from the system controller 13 indicating the end of the printing operation. If the coefficient addition unit 85 does not detect the end of the printing operation (ACT25, NO), it repeats ACT23 and ACT24 until it detects the end of the printing operation. In other words, the coefficient adding section 85 repeats setting of the coefficient K based on the number of lighting times for each fixed period. When the coefficient adding unit 85 detects the end of the printing operation (ACT25, YES), it ends the coefficient setting process.

An example of setting the coefficient K in the above-mentioned ACT24 will be explained.
FIG. 8 is a diagram illustrating an example of setting the coefficient K.
Here, the value of the number of lighting times CNT is assumed to be the number of lighting times X. The increase/decrease value of the coefficient K is associated with the number of lighting times X. The relationship between the increase/decrease value of the coefficient K and the number of lighting times X may be stored in the memory 23.

When the number of lighting times X is within a certain predetermined range, the increase/decrease value of the coefficient K is 0. For example, the predetermined range is a range of more than 25 times and no more than 75 times. The lower limit of 25 times and the upper limit of 75 times are examples, and both can be set as appropriate. The predetermined range is a range in which a stable image can be supplied. For example, as the coefficient K increases, the number of lighting times X tends to increase. As a result, the heater 73 repeats ON/OFF in a very short period of time, which worsens the flicker. On the other hand, as the coefficient K decreases, the number of lighting times X tends to decrease. As a result, ripples are more likely to occur. In view of these circumstances, the predetermined range is set within a range that maintains a balance between preventing deterioration of flicker and reducing ripples, and provides a stable image.

When the number of lighting times X is greater than a predetermined range, the increase/decrease value of the coefficient K is a negative value. When the number of lighting times X is greater than 75 times and less than 100 times, the increase/decrease value of the coefficient K is -0.1. When the number of lighting times X is more than 100 times, the increase/decrease value of the coefficient K is -0.2. The upper limit value and lower limit value regarding the number of lighting times X are merely examples, and both can be set as appropriate. Although the increase/decrease value of the coefficient K when the number of lighting times X is greater than a predetermined range is divided into two stages, the present invention is not limited thereto. The coefficient K may be increased or decreased by one step, or by three or more steps. The increase/decrease values for each stage are merely examples, and all can be set as appropriate. When the increase/decrease value of the coefficient K is divided into multiple stages, the increase/decrease value of the coefficient K increases in the negative direction as the number of lighting times X increases. The reason why the increase/decrease value of the coefficient K is set to a negative value is to ensure that the number of lighting times X falls within a predetermined range. That is, as the coefficient K becomes smaller, the effect of the high frequency component HPF on the corrected temperature value WAE becomes smaller. As a result, the number of lighting times X is reduced, and deterioration of flicker is prevented.

When the number of lighting times X is below a predetermined range, the increase/decrease value of the coefficient K is a positive value. When the number of lighting times X is more than 10 times and less than 25 times, the increase/decrease value of the coefficient K is +0.1. When the number of lighting times X is less than 25 times, the increase/decrease value of the coefficient K is +0.2. The upper limit value and lower limit value regarding the number of lighting times X are merely examples, and both can be set as appropriate. Although the increase/decrease value of the coefficient K when the number of lighting times X is below a predetermined range is divided into two stages, the present invention is not limited thereto. The coefficient K may be increased or decreased by one step, or by three or more steps. The increase/decrease values for each stage are merely examples, and all can be set as appropriate. When the increase/decrease value of the coefficient K is divided into multiple stages, the increase/decrease value of the coefficient K increases in the positive direction as the number of lighting times X decreases. The reason why the increase/decrease value of the coefficient K is set to a positive value is to ensure that the number of lighting times X falls within a predetermined range. That is, as the coefficient K increases, the effect of the high frequency component HPF on the corrected temperature value WAE increases. As a result, the number of times X of lighting is increased and the ripple is reduced.

The coefficient adding unit 85 maintains the coefficient K when the number of lighting times X is within a certain predetermined range. Maintaining coefficient K is an example of setting coefficient K.
If the number of lighting times X is greater than a predetermined range, the coefficient adding unit 85 changes the coefficient K to be smaller. In this example, the coefficient addition unit 85 adds an increase/decrease value, which is a negative value, associated with the number of lighting times X to the current value of the coefficient K. The coefficient adder 85 changes the coefficient K to a value smaller than the current value. Changing the coefficient K is an example of setting the coefficient K.

The coefficient adding unit 85 changes the coefficient K to be larger when the number of lighting times X is below a predetermined range. In this example, the coefficient addition unit 85 adds an increase/decrease value, which is a positive value, associated with the number of lighting times X to the current value of the coefficient K. The coefficient adder 85 changes the coefficient K to a value larger than the current value.

Note that although the initial value of the coefficient K has been described as being an arbitrary predetermined value, it is not limited to this. The coefficient adder 85 may set the initial value of the coefficient K based on the input voltage of the heater 73. In this example, the coefficient adder 85 obtains the value of the input voltage to the heater 73 detected by the voltage detector 75. The coefficient adding unit 85 may change the initial value of the coefficient K depending on whether the value of the input voltage is more positive than the rated voltage or negative. This is because the ripple changes depending on the input voltage. For example, if the value of the input voltage is more positive than the rated voltage, the ripple may become large, so the number of times the heater 73 is turned on tends to decrease. In this case, the coefficient adder 85 may set a value larger than 0.6 (60%) as the initial value of the coefficient K. On the other hand, for example, if the value of the input voltage is a value more negative than the rated voltage, the ripple may become smaller, so the number of times the heater 73 is turned on tends to increase. In this case, the coefficient adder 85 may set a value smaller than 0.6 (60%) as the initial value of the coefficient K.

According to this example, the coefficient adding unit 85 can shorten the time it takes to bring the number of lighting times X within a certain predetermined range after the heater 73 of the fixing device 21 starts being energized. Therefore, the processing load on the coefficient adding section 85 is reduced.

As described above, the image forming apparatus 1 includes a fixing device 21 that includes a heat roller 71 that heats a toner image formed on a medium and fixes it on the medium, and a heater 73 that heats the heat roller 71. A temperature control device (heater energization control circuit 14) is provided. The heater energization control circuit 14 controls the temperature of the heat roller 71 to which heat is transmitted from the heater 73 by supplying power to the heater 73. The heater energization control circuit 14 includes a temperature estimation section 81 that estimates the temperature of the heat roller 71 based on the energization of the heater 73 . Furthermore, the heater energization control circuit 14 includes a high frequency component extraction section 83 that extracts a high frequency component HPF of the temperature detection result Td. The heater energization control circuit 14 also includes a counting section 84 that counts the number of lighting times CNT of the heater 73 based on the energization of the heater 73 . Further, the heater energization control circuit 14 sets a coefficient K based on the number of lighting times CNT, and calculates a corrected temperature value WAE by adding the result of multiplying the high frequency component HPF by the coefficient K to the temperature detection result Td. Equipped with The heater energization control circuit 14 includes a control signal generation section 88 that outputs an energization pulse Ps for controlling the power supplied to the heater 73 based on the corrected temperature value WAE.

With such a configuration, even if the temperature sensor 74 detects the temperature of the heat roller 71 with poor responsiveness, the temperature control device is able to track the surface temperature of the heat roller 71 based on the temperature estimation result. can. Thereby, it is possible to prevent overshoot, temperature ripple, and the like from occurring. Further, the temperature control device can adjust the effect of the high frequency component HPF on the corrected temperature value WAE by setting the coefficient K based on the number of lighting times CNT. Thereby, the temperature control device can reduce the temperature ripple of the fixing device 21 without worsening the flicker depending on the number of lighting times CNT, and can supply a stable image.

Further, the counting unit 84 counts the number of lighting times CNT for each fixed period. The coefficient adding unit 85 sets the coefficient K based on the number of times of lighting CNT for each fixed period.
According to such a configuration, the temperature control device can set the repetition coefficient K at fixed time intervals. Thereby, the temperature control device can repeatedly set the coefficient K so that the temperature ripple of the fixing device 21 can be reduced without deteriorating flicker.

Further, the coefficient adding unit 85 maintains the coefficient K when the number of lighting times CNT is within a certain predetermined range. The coefficient adding unit 85 changes the coefficient K to be smaller when the number of times of lighting CNT is greater than a predetermined range. The coefficient adding unit 85 changes the coefficient K to be larger when the number of times of lighting CNT is below a predetermined range.
According to such a configuration, the temperature control device can adjust the number of times of lighting CNT to fall within a predetermined range. Thereby, the temperature control device can reduce the temperature ripple of the fixing device 21 without worsening the flicker depending on the number of lighting times CNT, and can supply a stable image.

Note that the functions described in each of the above-described embodiments are not limited to being configured using hardware, but can also be realized using software by loading a program in which each function is described into a computer. Further, each function may be configured by selecting either software or hardware as appropriate.

Although several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

DESCRIPTION OF SYMBOLS 1... Image forming apparatus, 11... Housing, 12... Communication interface, 13... System controller, 14... Heater energization control circuit, 15... Display section, 16... Operation interface, 17... Paper tray, 18... Paper output tray, 19 ...Conveyance section, 20...Image forming section, 21...Fixing device, 22...Processor, 23...Memory, 31...Paper feed conveyance path, 32...Sheet discharge conveyance path, 33...Pickup roller, 41...Process unit, 42...Exposure device, 43...transfer mechanism, 51...photosensitive drum, 52...electrostatic charger, 53...developing device, 61...primary transfer belt, 62...secondary transfer opposing roller, 63...primary transfer roller, 64...secondary transfer roller , 71... Heat roller, 72... Press roller, 73... Heater, 74... Temperature sensor, 75... Voltage detector, 81... Temperature estimation section, 82... Estimation history holding section, 83... High frequency component extraction section, 84... Counting section , 85... Coefficient addition section, 86... Target temperature output section, 87... Difference comparison section, 88... Control signal generation section, 89... Power supply circuit.

Claims (5)

A temperature control device that controls the temperature of a temperature-controlled object to which heat is propagated from the heater by supplying power to the heater,
The temperature control device includes:
a temperature estimation unit that estimates the temperature of the temperature controlled object based on energization of the heater;
a high frequency component extractor that extracts a high frequency component of the temperature estimation result;
a counting unit that counts the number of times the heater is turned on based on energization of the heater;
A correction in which a coefficient for adjusting the high frequency component to be added to the temperature detection result of the temperature control target by the temperature sensor is set based on the number of lighting times, and a result of multiplying the high frequency component by the coefficient is added to the temperature detection result. an addition unit that calculates a temperature value;
a control signal generation unit that outputs an energization pulse for controlling power supplied to the heater based on the corrected temperature value;
A temperature control device comprising: The counting unit counts the number of times the lighting is lit every certain period,
The addition unit sets the coefficient based on the number of times the lighting is lit for each fixed period.
The temperature control device according to claim 1. The adding unit maintains the coefficient when the number of lighting times is within a certain range, changes the coefficient to be smaller when the number of lighting times is greater than the range, and changes the coefficient so that the number of lighting times is less than or equal to the range. If so, the temperature control device according to claim 1 or 2, wherein the coefficient is changed to be larger. The temperature control device according to any one of claims 1 to 3, wherein the adding section sets the initial value of the coefficient based on the input voltage of the heater. a fixing device having a fixing rotary body that heats a toner image formed on a medium to fix it on the medium; and a heater that heats the fixing rotary body;
a temperature control unit that controls the temperature of the fixing rotor through which heat is propagated from the heater by supplying power to the heater;
The temperature control section includes:
a temperature estimation unit that estimates the temperature of the fixing rotor based on energization of the heater;
a high frequency component extractor that extracts a high frequency component of the temperature estimation result;
a counting unit that counts the number of times the heater is turned on based on energization of the heater;
A coefficient for adjusting the high frequency component to be added to the temperature detection result of the fixing rotor by the temperature sensor is set based on the number of lighting times, and a result of multiplying the high frequency component by the coefficient is added to the temperature detection result. an addition unit that calculates a corrected temperature value;
a control signal generation unit that outputs an energization pulse for controlling power supplied to the heater based on the corrected temperature value;
An image forming apparatus comprising: