JP2017058568A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device and the like that can properly control the temperature of a fixing device including a plurality of heaters and suppress the maximum power.SOLUTION: A fixing device 6 comprises: a plurality of heating parts 611, 612 that heat a fixing member; temperature detection parts 617, 618 that respectively detect the temperature of the plurality of heating parts; a calculation part that calculates a pattern to apply a driving power to the plurality of heating parts on the basis of an output from the temperature detection parts; a selection control part that sequentially selects a heating part to be a reference from the plurality of heating parts; and a power control part that controls switching elements 614,d 615 on the basis of the application pattern to select a half wave of an AC waveform and supplies a power to the heating part to be a reference as a driving power, deletes the half wave of the AC waveform of the application pattern overlapping with an application pattern of the heating part to be a reference, and controls the switching elements 614,d 615 to select a half wave of the AC waveform and supplies a power to the other heating part as a driving power.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fixing device and an image forming apparatus.

  Conventionally, in an image forming apparatus, in order to suppress the maximum power of the image forming apparatus as a whole, the required power of each unit is obtained in advance, and each unit is operated exclusively to integrate the units that operate simultaneously. The maximum power was set according to the value. In such an exclusive operation, a method of preferentially operating a unit having a great influence on image quality, such as a fixing device, and restricting the operation of other units is employed.

  However, when each unit cannot function exclusively due to its function, each unit may operate at the same time. In this case, the maximum power is temporarily exceeded. In some cases, the specification value of the maximum power of the forming apparatus had to be changed.

  In particular, in an image forming apparatus having a fixing device that drives a plurality of heaters independently, for example, in order to ensure the image quality of cardboard, control is performed to increase the driving frequency of the plurality of heaters and maintain the temperature of the fixing device. Will be exceeded and may exceed the maximum power.

  For this reason, a half-wave of the AC waveform that is the driving power of the heater is appropriately selected, and the AC waveform supplied to the plurality of heaters is half-processed using a control method (Patent Documents 1 and 2) that supplies the heater as driving power. It is known to suppress the maximum power by controlling exclusively for each wave. For example, when a half wave of an AC waveform is supplied as drive power to one heater, the maximum power can be suppressed by controlling exclusively so as not to supply drive power to the other heater. .

JP 2014-167543 A JP 2007-156110 A

  However, when the AC waveform supplied to a plurality of heaters is controlled exclusively for each half wave, the reference heater to which the half waveform of the AC waveform is supplied preferentially can be appropriately controlled, Other heaters that are not the reference have a problem in that appropriate temperature control cannot be performed because the required drive power is not supplied depending on the drive frequency of the reference heater.

  For example, in a fixing device having a central heater and two end heaters at both ends of the central heater, when the central heater is used as a reference heater and the supplied AC waveform is exclusively controlled every half wave, the end portion Since sufficient driving power is not supplied to the heater, there is a problem that the amount of heat generated is insufficient, the temperature distribution of the fixing device becomes uneven, and the image quality is affected.

  An object of the present invention is to provide a fixing device and an image forming apparatus capable of appropriately controlling temperature of a fixing device having a plurality of heaters and suppressing the maximum power.

In order to achieve the above object, a fixing device according to claim 1 is provided.
In a fixing device for fixing a color material attached to the recording medium by heating the recording medium with a fixing member,
A plurality of heaters for heating the fixing member;
An AC power supply for applying an AC voltage to the plurality of heaters;
A temperature detector for detecting the temperature of each of the plurality of heaters;
A calculation unit that calculates an application pattern of the driving power of the plurality of heaters based on an output of the temperature detection unit;
A selection control unit for selecting a reference heater from the plurality of heaters;
For the reference heater, appropriately select a half wave of the AC waveform of the AC power supply based on the application pattern calculated by the calculation unit, supply driving power from the AC power supply, and become the reference For the heaters other than the heater, appropriately select the half wave of the AC waveform of the AC power source based on the application pattern obtained by deleting the half wave of the AC waveform that overlaps the application pattern of the reference heater, and from the AC power source A power control unit for supplying driving power;
With
The selection control unit repeatedly performs a selection operation of the reference heater every time a predetermined condition is satisfied.

According to a second aspect of the present invention, in the fixing device according to the first aspect,
The selection control unit selects the reference heater using a predetermined random number.

According to a third aspect of the present invention, in the fixing device according to the first or second aspect,
The selection control unit selects the reference heater based on the required amount of heat of the plurality of heaters.

According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects,
The selection control unit selects the reference heater based on a predetermined cycle.

According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects,
The power control unit calculates a plurality of application patterns of the driving power of each of the plurality of heaters based on the output of the temperature detection unit, and sequentially switches the plurality of application patterns to select a half wave of an AC waveform, The driving power is supplied from the AC power source to the reference heater.

According to a sixth aspect of the present invention, in the image forming apparatus,
An image forming unit for forming a toner image on a recording medium;
The fixing device according to claim 1, further comprising: a fixing device that fixes the toner image to the recording medium through the recording medium on which the toner image is formed.

  According to the present invention, it is possible to appropriately control the temperature of a fixing device having a plurality of heaters and to suppress the maximum power.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment to which the present invention is applied. It is the schematic and control circuit diagram which expanded the roller part of the fixing device. It is explanatory drawing which shows an example of selection operation | movement of the half wave of an alternating current waveform. It is a flowchart explaining an example of control operation of a control part. It is explanatory drawing which shows an example of the control action on the basis of alternate of each roller. It is explanatory drawing which shows an example of the control operation which switches a several application pattern sequentially.

(Embodiment)
[1. Description of configuration]
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.
FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 100 according to an embodiment to which the present invention is applied. FIG. 2 is an enlarged schematic view and a control circuit diagram of the roller portion of the fixing device.

As shown in FIGS. 1 and 2, the image forming apparatus 100 according to the present exemplary embodiment includes image data acquired by reading a color image formed on a document, or an external information device (for example, a personal computer) via a network. An image is formed by superimposing colors on a sheet (recording medium) M based on image data input from a computer.
In addition, the image forming apparatus 100 travels the photosensitive drums 43Y, 43M, 43C, and 43K corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K) on the intermediate transfer belt 47a. This is a tandem type image forming apparatus that is arranged in series in the direction and sequentially transfers toner images of respective colors to a transfer medium in one procedure.

  Specifically, the image forming apparatus 100 of the present embodiment includes an image reading unit 1, an operation display unit 2, an image processing unit 3, an image forming unit 4, a transport unit 5, a fixing device 6, and a control. It comprises a part (not shown) etc.

  The image reading unit 1 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), a document image scanning device (scanner) 12, and the like.

  The automatic document feeder 11 conveys the document placed on the document tray by the conveyance mechanism and sends it out to the document image scanning device 12. The automatic document feeder 11 can continuously read images (including both sides) of a large number of documents placed on the document tray at once.

The document image scanning device 12 optically scans a document conveyed on the contact glass from the automatic document feeder 11 or a document placed on the contact glass, and reflects light from the document to a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and an original image is read. The image (analog image signal) read by the image reading unit 1 is subjected to predetermined image processing in the image processing unit 3.
Here, the image means not only image data such as graphics and photographs but also text data such as characters and symbols.

The operation display unit 2 includes a liquid crystal display (LCD) with a touch panel and the like, and functions as the display unit 21 and the operation unit 22.
The display unit 21 displays various operation screens, an image status display, an operation status of each function, and the like according to a display control signal input from the control unit.
The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit.

The image processing unit 3 includes a circuit that performs analog-digital (A / D) conversion processing and digital image processing.
It is configured with a circuit for performing processing.
The image processing unit 3 generates digital image data (RGB signals) by subjecting the analog image signal from the image reading unit 1 to A / D conversion processing. The image processing unit 3 performs color conversion processing, gradation reproduction processing (screen processing, etc.), correction processing (shading correction, etc.) according to initial settings or user settings, compression processing, and the like on the digital image data. . The image forming unit 4 is controlled based on the digital image data (YMCK signal) subjected to these processes.

  The image forming unit 4 includes exposure devices 41Y, 41M, 41C, and 41K, developing devices 42Y, 42M, 42C, and 42K, and a photosensitive drum 43Y, which are provided corresponding to different color components Y, M, C, and K. 43M, 43C, 43K, charging devices 44Y, 44M, 44C, 44K, lubricant application removing units 45Y, 45M, 45C, 45K, primary transfer rollers 46Y, 46M, 46C, 46K and intermediate transfer unit 47, etc. It is prepared for.

In the Y component unit of the image forming unit 4, the charging device 44Y charges the photosensitive drum 43Y. The exposure device 41Y is composed of, for example, a semiconductor laser, and irradiates the photosensitive drum 43Y with laser light corresponding to the Y component. As a result, an electrostatic latent image of the Y component is formed on the surface of the photosensitive drum 43Y. The developing device 42Y contains a Y-component developer (for example, a two-component developer composed of a toner having a small particle diameter and a magnetic material), and causes the Y-component toner to adhere to the surface of the photosensitive drum 43Y. Thus, the electrostatic latent image is developed (formation of a toner image).
Similarly, in the units for M component, C component, and K component, each color toner image is formed on the surface of the corresponding photosensitive drum 43M, 43C, 43K.

  The lubricant applying / removing portions 45Y, 45M, 45C, and 45K apply lubricant to the surfaces of the photosensitive drums 43Y, 43M, 43C, and 43K, and excessively adhere to the surfaces of the photosensitive drums 43Y, 43M, 43C, and 43K. Remove the lubricant and foreign matter.

The intermediate transfer unit 47 is configured by a plurality of support rollers 47b,... Being stretched with an endless intermediate transfer belt 47a serving as a transfer target.
When the intermediate transfer belt 47a is pressed against the photosensitive drums 43Y, 43M, 43C, and 43K by the primary transfer rollers 46Y, 46M, 46C, and 46K, the toner images of the respective colors are sequentially superimposed and primarily transferred onto the intermediate transfer belt 47a. . Then, the intermediate transfer belt 47a subjected to the primary transfer is pressed against the paper M by the secondary transfer roller 48, whereby the toner image is secondarily transferred to the paper M.
The toner remaining on the intermediate transfer belt 47a after the secondary transfer is removed by a blade or the like of the cleaning device 49.

The transport unit 5 includes a paper feeding device 51, a transport mechanism 52, a paper discharge device 53, and the like.
The paper feeding device 51 includes three paper feeding tray units 51a to 51c. In these paper feed tray units 51a to 51c, standard paper and special paper identified based on the basis weight, size, and the like of the paper M are stored for each preset type. The sheets M accommodated in the sheet feeding tray units 51a to 51c are sent out one by one from the uppermost part, and are conveyed to the image forming unit 4 by a conveying mechanism 52 including a plurality of conveying rollers such as a registration roller 52a. At this time, the registration unit in which the registration roller 52a is disposed corrects the inclination of the fed paper M and adjusts the conveyance timing.
The paper feeding device 51 is provided with a manual tray unit 51d for manually supplying the paper M.

  Then, in the image forming unit 4, the toner image on the intermediate transfer belt 47 a is secondarily transferred onto the image forming surface of the paper M at once, and a fixing process is performed in the fixing device 6. The sheet M on which the image has been formed is discharged to a discharge tray 53b outside the apparatus by a discharge device 53 having a discharge roller 53a.

  The fixing device 6 includes a fixing roller 61a and a pressure roller 61b that are fixing members. The fixing device 6 performs a fixing process for fixing the toner image, which is a color material transferred to the paper M. Further, the fixing roller 61a and the pressure roller 61b constitute a nip portion that sandwiches and conveys the paper M.

The fixing roller 61a is disposed on the image forming surface side of the paper M, and the fixing roller 61a rotates in accordance with driving of a driving unit such as a motor (not shown).
In addition, the fixing roller 61a has a configuration in which an elastic layer made of silicone rubber or the like is formed on the outer peripheral surface of a cylindrical metal core made of iron or the like, and has a built-in fixing heater 61c such as a halogen heater. At the same time, the sheet M is contacted with the image forming surface of the sheet M on which the toner image is transferred, and the sheet M is heated at a predetermined fixing temperature. That is, the fixing roller 61a contacts the image forming surface of the paper M while rotating and heats the paper M.
The predetermined fixing temperature is a temperature at which the amount of heat necessary to melt the toner when the paper M passes through the nip portion, and differs depending on the paper type of the paper M on which an image is formed.

  The pressure roller 61b is disposed to face the fixing roller 61a, and is pressed against the fixing roller 61a with a predetermined pressing force. That is, the pressure roller 61b functions as a pressure unit that sandwiches and pressurizes the paper M together with the fixing roller 61a.

  The pressure roller 61b has a configuration in which an elastic layer made of silicone rubber or the like is formed on the outer peripheral surface of a cylindrical metal core made of iron or the like. Further, since the surface of the pressure roller 61b is relatively hard with respect to the surface of the fixing roller 61a, the pressure roller 61b is pressed against the elastic layer on the surface of the fixing roller 61a while being pressed against the fixing roller 61a. A nip portion having a biting shape is formed.

[2. Description of fixing device configuration]
FIG. 2A is an enlarged schematic view of the roller portion of the fixing device, and FIG. 2B is a control circuit diagram of the fixing heater.
As shown in FIG. 2A, the central heater 611 is built in the central portion of the fixing roller 61a. Further, the end heaters 612 are provided at both ends of the central heater 611 inside the fixing roller 61a.

  The AC power source 613 outputs general AC power (for example, 100 V, 50 Hz, or 60 Hz).

  The switching element 614 and the switching element 615 are elements such as a thyristor and a bidirectional thyristor (triac), and are turned on when a trigger signal is applied to the gate as a control terminal. The output of AC power supply 613 is connected to the input terminals of switching element 614 and switching element 615, respectively, and the output terminals are connected to the power input terminals of central heater 611 and end heater 612, respectively.

  The control unit 616 controls the temperature of the central heater 611 and the end heater 612. Specifically, the control unit 616 functions as a power control unit together with the switching element 614 and the switching element 615, controls the switching element 614 and the switching element 615 with the control signals (CS61 and CS62), and outputs from the AC power supply 613. A half wave of the alternating waveform to be selected is selected and supplied to the central heater 611 and the end heater 612.

  The temperature detection unit 617 and the temperature detection unit 618 are temperature detection elements such as a temperature sensor, and are provided in the vicinity of the central heater 611 and the end heater 612, respectively, and detect the temperatures of the central heater 611 and the end heater 612. And output to the control unit 616.

  The zero cross detection unit 619 takes in the output of the AC power supply 613, generates a zero cross signal ZC61, and outputs it to the control unit 616.

[3. Explanation of selection of half wave of AC waveform]
Here, a method of selecting a half wave of the AC waveform output from the AC power source 613 by the switching element 614 and the switching element 615 and supplying the half wave to the central heater 611 and the end heater 612 will be described with reference to FIG.

  As shown in FIG. 3B, the zero-cross detection unit 619 detects a point where the AC waveform output from the AC power supply 613 passes ± 0 V, and generates a zero-cross signal ZC61 in which the output value is switched at the time of detection. And output to the control unit 616.

  As shown in FIG. 3C, the control unit 616 generates a control signal CS61 (control signal CS62) synchronized with the inputted zero cross signal ZC61 and applies it to the control terminal of the switching element 614 (switching element 615). To do.

  That is, as shown in FIG. 3, the switching element 614 (switching element 615) is turned “ON” in the period T1, the period T2, and the period T4 when the control signal CS61 (control signal CS62) is applied from the control unit 616. The half wave of the AC waveform output from the AC power source 613 is selected and supplied to the central heater 611 (end heater 612).

  On the other hand, in the period T3 in which the control signal CS61 (control signal CS62) is not applied from the control unit 616, the switching element 614 (switching element 615) remains “OFF” and is non-conductive, and thus is output from the AC power supply 613. The half wave of the alternating waveform is not selected.

  In addition, the switching element 614 (switching element 615) is maintained in a conductive state once a trigger signal (control signal) is applied to the gate, but returns to a non-conductive state when the voltage becomes 0 V as in an AC waveform. Therefore, even if it conducts in the cycle T2, it automatically returns to non-conduction in the cycle T3.

[4. Description of operation of fixing device]
Here, the operation of the fixing device 6 will be described with reference to the flowchart of FIG.
The control unit 616 determines whether or not to turn on the heater (supply driving power) (step S41). If it is determined that the heater is not turned on (step S41: No), the process returns to step S41. On the other hand, when the control unit 616 determines to turn on the heater (step S41: Yes), the control unit 616 calculates an application pattern of the central heater 611 and the end heater 612 as a calculation unit (step S42).

  For example, the control unit 616 serves as a calculation unit, based on the difference between the temperature of the central heater 611 detected by the temperature detection unit 617 and the target temperature, more specifically, the number of half-waves of the alternating waveform to be selected in a predetermined cycle. (Duty ratio) is calculated. Similarly, the control unit 616 calculates an application pattern as a calculation unit based on the difference between the temperature of the end heater 612 detected by the temperature detection unit 618 and the target temperature.

  Specifically, the so-called PID control (Proportional-Integral-Derivative Controller) is used to calculate the applied pattern by three elements: the deviation between the detected heater temperature and the target temperature, its integration, and differentiation. Ask.

  Here, the application pattern is a pattern in which a half wave of an alternating waveform having a predetermined period is selected based on the duty ratio.

  Next, the control unit 616 determines whether or not the reference flag is “0” (step S43). Here, the reference flag is a flag indicating whether the current reference heater is the central heater 611 or the end heater 612. For example, when the reference flag is “0”, the central heater 611 is It shows that it is a standard.

  When the control unit 616 determines that the reference flag is “0” (step S43: Yes), the central heater 611 is used as a reference (step S44), and the control unit 616 is a selection control unit and sets the reference flag to “1”. To the next reference heater (step S45), and the process proceeds to step S48.

  On the other hand, when the control unit 616 determines that the reference flag is not “0” (step S43: No), the end heater 612 is used as a reference (step S46), and the control unit 616 uses the reference flag as a selection control unit. The heater is changed to “0” and the next reference heater is switched (step S47), and the process proceeds to step S48.

  Then, the control unit 616 turns on the central heater 611 and the end heater 612 with the calculated application pattern (step S48). At this time, the control unit 616 gives priority to the application pattern of the heater serving as a reference, and the period in which the application pattern of the reference heater selects the half wave of the AC waveform is non-conductive among the application patterns of the other heater. The central heater 611 and the end heater 612 are controlled so as not to be simultaneously turned on in the same cycle.

  For example, when the central heater 611 is the reference, the control unit 616 uses the application pattern calculated in step S42 as it is as the power control unit as shown in FIG. 5A, and uses the cycle T1, the cycle T3, and the cycle. T4, cycle T5, cycle T8, and cycle T10 are set to “ON”. On the other hand, in the end heater 612, the half wave of the AC waveform of the application pattern that overlaps the application pattern of the reference central heater 611 among the calculated application patterns is deleted, and the period T1, the period T3, and the period T4 are deleted. The period T5, the period T8, and the period T10 are forcibly made non-conductive.

  Further, for example, when the end heater 612 is a reference, the control unit 616 uses the application pattern calculated in step S42 as the power control unit as shown in FIG. T5, cycle T7, and cycle T9 are set to “ON”. On the other hand, in the central heater 611, the half wave of the AC waveform of the application pattern that overlaps the application pattern of the end heater 612 serving as a reference is deleted from the calculated application patterns, and the period T1 to the period T5 and the period T7 are deleted. The period T9 is forcibly turned off.

  Finally, the control unit 616 determines whether or not the predetermined number of times has been completed (step S49). If the control unit 616 determines that the predetermined number of times has not been completed (step S49: No), the control unit 616 returns to step S49. If it is determined that the number of times has been completed (step S49: Yes), it is determined whether or not to turn on the heater (step S50).

  And when it judges that control part 616 does not end lighting of a heater (Step S50: No), it returns to Step S42, and when it is judged that lighting of a heater is ended (Step S50: Yes), processing is ended.

  That is, since the heater is turned on by alternately switching the reference heater every predetermined number of times, the amount of heat generated by one of the heaters is insufficient, the temperature distribution of the fixing device becomes uneven, and the image quality is affected. Can be prevented. Further, since the central heater 611 and the end heater 612 are not conducted at the same time, it is possible to prevent the maximum power from being exceeded.

  As described above, according to the fixing device 6 of the present embodiment, a plurality of heaters that heat the fixing member, the temperature detection units 617 and 618 that respectively detect the temperatures of the plurality of heaters, and the output of the temperature detection unit. Calculate the drive power application pattern of multiple heaters, select the reference heater alternately from the multiple heaters, control the switching element based on the applied pattern, select the AC waveform half wave, and use it as the drive power reference The half-wave of the AC waveform of the application pattern that overlaps the application pattern of the reference heating unit is deleted and the switching element is controlled to select the half-wave of the AC waveform and drive power as another power By providing the control unit 616 that supplies the heater, the temperature of the fixing device having a plurality of heaters can be appropriately controlled and the maximum power can be suppressed. Kill

  In the description of the embodiment, the central heater 611 and the end heater 612 are alternately switched as reference heaters every predetermined number of times, but the reference heaters may be selected in order, A reference heater may be selected using a random number. Further, a reference heater may be selected in accordance with the required heat amount of the central heater 611 and the end heater 612.

  For example, as the selection control unit, the control unit 616 obtains necessary heat amounts of the central heater 611 and the end heater 612 from the application pattern, and the heater having the larger required heat amount among the central heater 611 and the end heater 612 is given priority. Select the standard heater. As a result, the heater having the larger required heat quantity is set to a heater other than the reference heater, and the trouble of temperature control due to the temperature of the heater not sufficiently rising can be prevented.

  In the description of the embodiment, only one application pattern of the central heater 611 and the end heater 612 is calculated and each heater is turned on. However, a plurality of application patterns are calculated and the plurality of application patterns are sequentially switched. Then, a half wave of the AC waveform may be selected and supplied to the reference heater.

  For example, FIG. 6 is an explanatory diagram illustrating an example of a control operation for sequentially switching a plurality of application patterns. FIGS. 6A to 6F show application patterns having the same duty ratio (50%), and such application patterns are sequentially switched to select an AC waveform half wave.

  In this case, even when the duty ratio is the same (50%), since the heater is turned on with a plurality of application patterns, the load on the reference heater can be reduced.

  In the description of the embodiment, the fixing device 6 includes a fixing roller 61a and a pressure roller 61b that constitute a nip portion N that sandwiches and conveys the paper M, but a heating roller that is a heating member; A fixing belt, and the fixing belt is stretched between a heating roller and a fixing roller 61a, and the fixing roller 61a and the pressure roller 61b sandwich and convey the paper M via the fixing belt. N may be configured.

  In the description of the embodiment, for example, an image forming unit is provided for each color such as Y (yellow), M (magenta), C (cyan), and K (black), and a color image is formed on the sheet M. Although the image forming apparatus 100 to be formed is illustrated as an example, the present invention is not limited thereto, and may be an image forming apparatus that forms a monochrome image, for example.

  In the description of the embodiment, the fixing roller and the pressure roller are described separately, but may be considered as a pair of fixing members.

  In the description of the embodiment, paper is exemplified as the recording medium. However, the recording medium is not limited to paper, and may be any sheet that can form and fix a toner image. , Non-woven fabric, plastic film, leather, etc.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 4 Image forming part 6 Fixing apparatus 61a Fixing roller 61b Pressure roller 61c Fixing heater 611 Central heater 612 End heater 613 AC power supply 614,615 Switching element (electric power control part)
616 control unit (calculation unit, selection control unit, power control unit)
617, 618 Temperature detector 619 Zero cross detector M Paper (recording medium)
CS61, CS62 Control signal ZC61 Zero-cross signal

Claims (6)

In a fixing device for fixing a color material attached to the recording medium by heating the recording medium with a fixing member,
A plurality of heaters for heating the fixing member;
An AC power supply for applying an AC voltage to the plurality of heaters;
A temperature detector for detecting the temperature of each of the plurality of heaters;
A calculation unit that calculates an application pattern of the driving power of the plurality of heaters based on an output of the temperature detection unit;
A selection control unit for selecting a reference heater from the plurality of heaters;
For the reference heater, appropriately select a half wave of the AC waveform of the AC power supply based on the application pattern calculated by the calculation unit, supply driving power from the AC power supply, and become the reference For the heaters other than the heater, appropriately select the half wave of the AC waveform of the AC power source based on the application pattern obtained by deleting the half wave of the AC waveform that overlaps the application pattern of the reference heater, and from the AC power source A power control unit for supplying driving power;
With
The fixing device is characterized in that the selection controller repeatedly executes a selection operation of the reference heater every time a predetermined condition is satisfied.   The fixing device according to claim 1, wherein the selection control unit selects the reference heater using a predetermined random number.   The fixing device according to claim 1, wherein the selection control unit selects the reference heater based on a necessary heat amount of the plurality of heaters.   The fixing device according to claim 1, wherein the selection control unit selects the reference heater based on a predetermined cycle.   The power control unit calculates a plurality of application patterns of the driving power of each of the plurality of heaters based on the output of the temperature detection unit, and sequentially switches the plurality of application patterns to select a half wave of an AC waveform, 5. The fixing device according to claim 1, wherein driving power is supplied from the AC power source to the reference heater. 6. An image forming unit for forming a toner image on a recording medium;
An image forming apparatus comprising: the fixing device according to claim 1, wherein the toner image is fixed to the recording medium through the recording medium on which the toner image is formed. .

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