JP2015197671A - Fixing apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably satisfy a flicker regulation value.SOLUTION: A control section performs power-on control of first and second heaters by switching a switching section, on the basis of an arrangement pattern 2 of on-sections and off-sections, based on a half-wave period of an AC power supply. When a flicker regulation value cannot be satisfied with a set arrangement pattern combination, the control section performs power-on control of the first and second heaters, by use of an arrangement pattern formed by changing the arrangement of the on-sections and the off-sections, so as to satisfy the flicker regulation value with the same duty ratio of the arrangement pattern 2 in the first heater, for example.

Description

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

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus having a large number of functions such as a printer, a copier, and a facsimile is widely known. In this image forming apparatus, an image is formed on a sheet through a series of processes in which the image is transferred to the sheet and then the image is fixed on the sheet. The image forming apparatus includes a fixing device that performs a fixing process. The fixing device has a fixing heater for performing heat fixing. As the fixing heater, for example, a halogen lamp can be used.

  In recent years, energy saving (reduction of power consumption) has been demanded in image forming apparatuses. It has been found that reducing the power of the fixing device is effective in realizing energy saving of the image forming apparatus. To reduce the power of the fixing device, it is common to reduce the heat capacity of the fixing device. However, if the heat capacity of the fixing device is reduced, the temperature ripple of the fixing device increases, and the fixing performance is greatly affected. There's a problem.

  Therefore, conventionally, for example, power ripple control by variable duty control such as phase control or PWM control is performed to reduce the temperature ripple of the fixing device. However, the fixing device has a problem that various standards such as noise terminal voltage, harmonic distortion regulation, and flicker regulation must be cleared in addition to the problem of temperature ripple. As one of effective power control methods for clearing these various regulations, there is known a technique for controlling the lighting of a heater by an on / off pattern with a half wave period of an AC power supply as one unit.

  For example, Patent Document 1 discloses an arrangement pattern in which all of the sections having the smaller number of half-waves are all non-continuous among the on section to be turned on and the off section to be turned off in one control cycle. Describes an image forming apparatus for controlling on / off of a fixing heater based on the above. Patent Document 2 describes a fixing device that supplies electric power to a heater so that the heater is turned on by an AC discontinuous pattern so that the power is less than the rated energized power by AC continuous lighting at least for a predetermined time from the ON timing of the heater. Has been. Patent Document 3 describes a fixing device in which a control unit selects one of a plurality of specified cycles according to the length of a specified cycle, and then controls switching of the switching unit over the selected specified cycle. Yes.

JP 2009-237070 A JP-A-9-80961 Japanese Patent Laid-Open No. 11-344899

  However, the image forming apparatus and the fixing apparatus described in Patent Documents 1 to 3 have the following problems. That is, in Patent Documents 1 to 3, when a plurality of heaters are provided in the fixing device, lighting control is performed for each heater by an on / off pattern of an AC power supply in a half-wave unit. Even if a simple arrangement pattern is used, the flicker regulation value (standard) may not be cleared depending on the combination of arrangement patterns for each heater.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device and an image forming apparatus that can reliably clear a flicker regulation value.

  In order to solve the above-described problems, the fixing device according to the present invention includes a plurality of heaters that fix an image on a sheet, an ON state in which the plurality of heaters and an AC power source are connected, and a connection between the plurality of heaters and the AC power source. A switching unit that switches between an off state and a controller that performs lighting control of a plurality of heaters by switching the switching unit according to an array pattern of an on section and an off section in units of a half-wave period of an AC power supply. The control unit, when simultaneously controlling lighting of each of the plurality of heaters with an array pattern having a predetermined duty ratio, satisfies a flicker regulation value set with the same duty ratio of the array pattern in at least one heater. The lighting control is performed using an arrangement pattern in which the arrangement of the ON section and the OFF section is changed.

An image forming apparatus according to the present invention includes: an image forming unit that forms an image on a sheet; a fixing device that fixes an image formed by the image forming unit on the sheet; and a control unit that controls at least the fixing device. The fixing device includes a plurality of heaters for fixing an image on a sheet, a switching unit that switches between an on state in which the plurality of heaters and the AC power source are connected, and an off state in which the connection between the plurality of heaters and the AC power source is released. And the control unit performs lighting control of the plurality of heaters by switching the switching unit according to the arrangement pattern of the on section and the off section in units of half-wave periods of the AC power supply, and each of the plurality of heaters is controlled. When controlling lighting simultaneously with an array pattern with a predetermined duty ratio, the duty ratio of the array pattern is set to be the same for at least one heater. And it performs lighting control by using the array pattern for changing the sequence of ON intervals and OFF intervals so as to satisfy the flicker regulation values.

  According to the present invention, even in a combination of arrangement patterns that cannot satisfy the flicker regulation value, the arrangement pattern in which the duty ratio of the arrangement pattern is the same and the arrangement of the on section and the off section is changed so as to satisfy the flicker regulation value. Therefore, the flicker regulation value can be surely cleared.

1 is a diagram illustrating a configuration example of an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a diagram illustrating a block configuration example of a fixing device. It is a figure for demonstrating the arrangement | sequence pattern for carrying out lighting control of the 1st and 2nd heater. It is a figure for demonstrating the current waveform of the arrangement pattern whose duty ratio is 88.89%. It is a figure which shows the flicker measurement value in the arrangement | sequence pattern which controls lighting of the 1st and 2nd heater, and an arrangement | sequence pattern (the 1). It is a figure which shows the flicker measured value in the arrangement | sequence pattern and arrangement | sequence pattern which carry out lighting control of the 1st and 2nd heater (the 2). It is a figure which shows the flicker measured value in the arrangement | sequence pattern and arrangement | sequence pattern which carry out lighting control of the 1st and 2nd heater (the 3). It is a figure which shows the flicker measured value in the arrangement | sequence pattern and arrangement | sequence pattern which carry out lighting control of the 1st and 2nd heater (the 4). It is a figure which shows the flicker measured value in the arrangement | sequence pattern and arrangement | sequence pattern which carry out lighting control of the 1st and 2nd heater (the 5). It is a figure which shows the flicker measured value in the arrangement | sequence pattern and arrangement | sequence pattern which carry out lighting control of the 1st and 2nd heater (the 6). It is a figure which shows the flicker measured value in the arrangement | sequence pattern and arrangement | sequence pattern which carry out lighting control of the 1st and 2nd heater (the 7). It is a figure which shows the flicker measured value in the arrangement | sequence pattern and arrangement | sequence pattern which carry out lighting control of the 1st and 2nd heater (the 8). It is a figure which shows the flicker measured value in the arrangement | sequence pattern and arrangement | sequence pattern which carry out lighting control of the 1st and 2nd heater (the 9). It is a figure which shows the flicker measured value in the arrangement | sequence pattern and arrangement | sequence pattern which carry out lighting control of the 1st and 2nd heater (the 10). It is a figure which shows the flicker measured value in the arrangement | sequence pattern which controls lighting of the 1st and 2nd heater, and an arrangement | sequence pattern (the 11). It is a figure which shows the flicker measured value in the arrangement | sequence pattern which controls lighting of the 1st and 2nd heater, and an arrangement | sequence pattern (the 12). It is a figure which shows the flicker measured value at the time of lighting-controlling the 1st and 2nd heater by the combination of a predetermined arrangement pattern. It is a figure which shows the structural example of the table which matches and memorize | stores the combination of the arrangement pattern of the 1st and 2nd heater which cleared the flicker regulation value, and the flicker measured value. 6 is a flowchart illustrating an operation example of the image forming apparatus during fixing processing.

  Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<First Embodiment>
[Configuration example of image forming apparatus]
First, the image forming apparatus 100 according to the present invention will be described. FIG. 1 shows an example of the configuration of an image forming apparatus 100 according to the present invention. As shown in FIG. 1, the image forming apparatus 100 is called a tandem type image forming apparatus, and includes an automatic document feeder 80 and an apparatus main body 102. The automatic document conveyance unit 80 is attached to the upper part of the apparatus main body 102 and sends out the paper set on the conveyance table to the image reading unit 90 of the apparatus main body 102 by a conveyance roller or the like.

  The apparatus main body 102 includes an operation display unit 70, an image reading unit 90, an image forming unit 10, an intermediate transfer belt 8, a paper feeding unit 20, a registration roller pair 32, a fixing device 200, and automatic paper reversal conveyance. And a unit 60 (Auto Duolex Unit: hereinafter referred to as ADU).

  The operation display unit 70 includes a touch panel in which a display unit and an input unit are combined, and a plurality of operation keys including a start key and a determination key provided in a peripheral part of the touch panel. The operation display unit 70 displays an operation screen or the like, or receives information such as an image forming condition or a fixing condition input by a touch operation on the operation screen or an operation key operation.

  The image reading unit 90 scans and exposes the document placed on the document table or the document transported by the automatic document transport unit 80 by the optical system of the scanning exposure device, and the image of the scanned document is CCD (Charge Coupled Devices). ) Photoelectric conversion is performed by an image sensor to generate an image information signal. The image information signal is output to the image forming unit 10 after being subjected to analog processing, analog / digital (hereinafter referred to as A / D) conversion processing, pseudo correction, image compression processing, and the like by an image processing unit (not shown).

  The image forming unit 10 forms an image by electrophotography, and includes an image forming unit 10Y that forms a yellow (Y) image, an image forming unit 10M that forms a magenta (M) image, The image forming unit 10C forms a cyan (C) color image, and the image forming unit 10K forms a black (K) color image. In this example, common function names, for example, Y, M, C, and K indicating colors to be formed are added to the back of the reference numeral 10.

  The image forming unit 10Y includes a photosensitive drum 1Y, a charger 2Y, an exposure unit (optical writing unit) 3Y, a developing unit 4Y, and a cleaning unit 6Y arranged around the photosensitive drum 1Y. The image forming unit 10M includes a photosensitive drum 1M, a charger 2M, an exposure unit 3M, a developing unit 4M, and a cleaning unit 6M disposed around the photosensitive drum 1M. The image forming unit 10C includes a photosensitive drum 1C, and a charger 2C, an exposure unit 3C, a developing unit 4C, and a cleaning unit 6C disposed around the photosensitive drum 1C. The image forming unit 10K includes a photosensitive drum 1K, a charger 2K, an exposure unit 3K, a developing unit 4K, and a cleaning unit 6K disposed around the photosensitive drum 1K.

  Respective photosensitive drums (image carriers) 1Y, 1M, 1C, and 1K in the image forming units 10Y, 10M, 10C, and 10K, chargers 2Y, 2M, 2C, and 2K, exposure units 3Y, 3M, 3C, and 3K, development The devices 4Y, 4M, 4C, and 4K and the cleaning units 6Y, 6M, 6C, and 6K have the same configuration. In the following description, Y, M, C, and K are not used unless particularly distinguished.

  The charger 2 charges the surface of the photosensitive drum 1 almost uniformly. The exposure unit 3 is composed of, for example, an LPH (LED Print Head) having an LED array and an imaging lens, or a polygon mirror type laser exposure scanning device, and the photosensitive drum 1 is irradiated with laser light based on an image information signal. Scan to form an electrostatic latent image. The developing device 4 develops the electrostatic latent image formed on the photosensitive drum 1 with toner. As a result, a toner image which is a visible image is formed on the photosensitive drum 1.

  The intermediate transfer belt 8 is stretched by a plurality of rollers and is rotatably supported. Along with the rotation of the intermediate transfer belt 8, the primary transfer roller 7 and the photosensitive drum 1 rotate, and a predetermined voltage is applied between the primary transfer roller 7 and the photosensitive drum 1, whereby the photosensitive member. The toner image formed on the drum 1 is transferred onto the intermediate transfer belt 8 (primary transfer).

  The paper feed unit 20 has a plurality of paper feed trays 20A and 20B in which paper P such as A3 and A4 is accommodated. The paper P transported from the paper feed trays 20A, 20B by the transport rollers 22, 24, 26, 28, etc. is transported to the loop roller pair 30. Note that the number of paper feed trays is not limited to two. Further, a single or a plurality of large-capacity paper feeders that can accommodate a large-capacity paper P may be connected as necessary.

  The leading end of the paper P transported to the loop roller pair 30 is abutted against the registration roller pair 32. The registration roller pair 32 forms a loop in the abutted paper P, and corrects bending (for example, skew) of the paper P with respect to the paper transport direction D1. The paper P in which the bending of the paper P is corrected is conveyed to the secondary transfer roller 34 at a predetermined timing. In the secondary transfer roller 34, the Y, M, C, K toner images transferred onto the intermediate transfer belt 8 are collectively transferred onto the surface of the paper P conveyed by the resist roller pair 32 (secondary transfer). . The second-transferred paper P is conveyed to the fixing device 200 on the downstream side in the paper conveyance direction D1.

  The fixing device 200 includes a heating roller and a pressure roller. The toner image on the surface of the paper P is fixed to the paper P by applying pressure and heat treatment to the paper P on which the toner image is transferred by the secondary transfer roller 34. Let The fixing device 200 will be described later. A transport path switching unit 48 for switching the transport path of the paper P to the discharge path side or the ADU 60 side is provided on the downstream side of the fixing apparatus 200 in the paper transport direction D1. The transport path switching unit 48 performs transport path switching control based on the selected print mode (single-sided print mode, double-sided print mode, or the like).

  The paper P on which single-sided printing has been completed in the single-sided printing mode or the paper P on which double-sided printing has been completed in the double-sided printing mode is discharged onto the paper discharge tray by the paper discharge roller 46. In the double-sided printing mode, when an image is formed on the back side of the paper P, the paper P on which the image is formed on the front side is conveyed to the ADU 60 via the conveyance roller 62 and the like. In the switchback path of the ADU 60, the reverse rotation control of the ADU roller 64 causes the rear end of the paper P to be transported to the U-turn path section, and is reversed by the transport rollers 66 and 68 provided in the U-turn path section. In this state, the paper is fed again to the secondary transfer roller 34.

[Block Configuration Example of Image Forming Apparatus]
FIG. 2 is a block diagram illustrating a configuration of an image forming apparatus including the fixing device 200. As illustrated in FIG. 2, the image forming apparatus 100 includes an AC power supply 210, a fixing device 200, a control unit 250, and a storage unit 252. The AC power supply 210 is installed in an office or the like where the image forming apparatus 100 is installed, and supplies predetermined power to the image forming apparatus 100 including the fixing device 200.

  The fixing device 200 includes a first heater 220, a temperature sensor (temperature detection unit) 222, a second heater 230, a temperature sensor (temperature detection unit) 232, and switching units 260 and 270. . The first and second heaters 220 and 230 are connected to the AC power supply 210 in parallel via a power line.

  The first heater 220 is composed of, for example, a halogen heater or the like, and controls the temperature of the fixing device 200 by turning on and off based on power with a predetermined duty ratio supplied from the AC power supply 210. The temperature sensor 222 is composed of, for example, a thermistor and is provided in the vicinity of the first heater 220. The temperature sensor 222 detects the temperature of the first heater 220 and outputs temperature information obtained by the detection to the control unit 250.

  The switching unit 260 is provided between the AC power supply 210 and the first heater 220 via a power line, and includes a switching element such as a triac. The switching unit 260 is configured to be able to switch between an on state in which the AC power source 210 and the first heater 220 are connected and an off state in which the connection between the AC power source 210 and the first heater 220 is released.

  The second heater 230 is composed of, for example, a halogen heater or the like, and controls the temperature of the fixing device 200 by turning on and off based on power with a predetermined duty ratio supplied from the AC power supply 210. The temperature sensor 232 is composed of, for example, a thermistor and is provided in the vicinity of the second heater 230. The temperature sensor 232 detects the temperature of the second heater 230 and outputs temperature information obtained by the detection to the control unit 250.

  The switching unit 270 is provided between the AC power supply 210 and the second heater 230 via a power line, and includes a switching element such as a triac. The switching unit 270 is configured to be able to switch between an on state in which the AC power source 210 and the second heater 230 are connected and an off state in which the connection between the AC power source 210 and the second heater 230 is released.

  The controller 250 controls the lighting of the first and second heaters 220 and 230 based on the temperature information of the first and second heaters 220 and 230 output from the temperature sensors 222 and 232. Specifically, the control unit 250 calculates a temperature difference based on a comparison result between preset target temperatures of the first and second heaters 220 and 230 and measured temperatures detected by the temperature sensors 222 and 232. Then, on / off control of the first and second heaters 220 and 230 is performed based on the calculated temperature difference. When the lighting control of the first and second heaters 220 and 230 is performed, the control unit 250 switches and controls the on / off states of the switching units 260 and 270 based on the duty pattern arrangement pattern corresponding to the temperature difference. The array pattern is configured by an on / off pattern with a half-wave period of the AC power supply 210 as a unit. Note that the control unit 250 may be provided in the fixing device 200.

  Further, the control unit 250 executes a flicker priority mode that prioritizes reducing flicker, a temperature ripple priority mode that prioritizes reducing temperature ripple, and a mode that prioritizes both priority modes. Each mode can be selected on the operation screen of the operation display unit 70 or the like.

  The storage unit 252 includes, for example, a non-volatile semiconductor memory, an HDD (Hard Disk Drive), or the like. The storage unit 252 stores a table TB1 that stores an array pattern for controlling lighting of first and second heaters 220 and 230, which will be described later, and a table that stores flicker measurement values of each array pattern that clears the flicker specified value. TB2 is stored. The flicker measurement value is, for example, a value measured in advance before the image forming apparatus 100 is shipped.

[Configuration example of array pattern]
Next, an arrangement pattern of current waveforms in half-wave units will be described. FIG. 3 shows an example of the arrangement pattern of current waveforms in half-wave units. In FIG. 3, the current waveform in units of half-waves is indicated by a rectangle, the ON interval is indicated by a colored rectangle, and the OFF interval is indicated by a white rectangle. Further, the “judgment result” in FIG. 3 indicates whether or not the flicker measurement value when each of the array patterns 1 to 11 (one control section) is continuously lit clears a preset flicker specified value. It is a result. In this example, when the flicker measurement value exceeds the flicker specified value (for example, pst = 0.9), the determination result is “x”, and when the flicker measurement value is less than the flicker specified value, the determination result is “◯”. It was. The frequency of the AC power supply 210 is 50 Hz, and the half wave period is 10 msec.

  The array pattern 1 is a duty pattern having a duty ratio of 88.89%. Arrangement pattern 1 includes nine half-wave periods as one control section, and is composed of eight on sections and one off section. One control section of the array pattern 1 is 90 msec. When the lighting control of the heater was performed using the array pattern 1, the flicker determination was “x”.

  FIG. 4 shows a voltage waveform when a heater is applied based on the arrangement pattern 1. In FIG. 4, the solid line is a state where a voltage is applied to both ends of the heater, and the broken line is a state where a voltage is not applied to both ends of the heater. In the arrangement pattern 1, the second voltage waveform is off, and the other voltage waveforms are on. In the following description, the voltage waveforms of the array patterns 2 to 11 are omitted for convenience.

  Returning to FIG. 3, the arrangement pattern 2 is a duty pattern having a duty ratio of 85.71%. The array pattern 2 includes seven half-wave periods as one control section, and includes six on sections and one off section. Specifically, the second column is an off section, and the other is an on section. One control section of the array pattern 2 is 70 msec. When the lighting control of the heater was performed using the array pattern 2, the flicker determination was “x”.

  The array pattern 3 is a duty pattern having a duty ratio of 81.8%. Arrangement pattern 3 is composed of nine on sections and two off sections, with 11 half-wave periods as one control section. Specifically, the second and seventh rows are off sections, and the other are on sections. One control section of the array pattern 3 is 110 msec. When the lighting control of the heater was performed using the arrangement pattern 3, the flicker determination was “◯”.

  The array pattern 4 is a duty pattern with a duty ratio of 80%. The array pattern 4 is composed of four on sections and one off section, with five half-wave periods as one control section. Specifically, the second column is an off section, and the other is an on section. One control section of the array pattern 4 is 50 msec. When the heater lighting control was performed using the arrangement pattern 4, the flicker determination was “◯”.

  The array pattern 5 is a duty pattern with a duty ratio of 71.43%. The array pattern 5 is composed of five on sections and two off sections, with seven half-wave periods as one control section. Specifically, the second row and the fifth row are off sections, and the others are on sections. One control section of the array pattern 5 is 70 msec. When the heater lighting control was performed using the arrangement pattern 5, the flicker determination was “◯”.

  The array pattern 6 is a duty pattern having a duty ratio of 66.67%. The array pattern 6 is composed of two on sections and one off section, with three half-wave periods as one control section. Specifically, the second column is an off section, and the other is an on section. One control section of the array pattern 6 is 30 msec. When the heater lighting control was performed using the arrangement pattern 6, the flicker determination was “◯”.

  The array pattern 7 is a duty pattern having a duty ratio of 57.14%. The array pattern 7 is composed of four on sections and three off sections, with seven half-wave periods as one control section. Specifically, the second column, the fifth column, and the seventh column are off sections, and the others are on sections. One control section of the array pattern 7 is 70 msec. When the heater lighting control was performed using the arrangement pattern 7, the flicker determination was “◯”.

  The array pattern 8 is a duty pattern having a duty ratio of 55.56%. The array pattern 8 is composed of five on sections and four off sections, with nine half-wave periods as one control section. Specifically, the third column, the sixth column, the eighth column, and the ninth column are off sections, and the others are on sections. One control section of the array pattern 8 is 90 msec. When the heater lighting control was performed using the array pattern 8, the flicker determination was “x”.

  The array pattern 9 is a duty pattern with a duty ratio of 40%. The array pattern 9 is composed of two on sections and three off sections, with five half-wave periods as one control section. Specifically, the first column and the fourth column are on sections, and the others are off sections. One control section of the array pattern 9 is 50 msec. When the lighting control of the heater was performed using the arrangement pattern 9, the flicker determination was “◯”.

  The array pattern 10 is a duty pattern having a duty ratio of 33.33%. The array pattern 10 includes three half-wave periods as one control section, and is composed of one on section and two off sections. Specifically, the first column is an on section, and the other is an off section. One control section of the array pattern 10 is 30 msec. When the lighting control of the heater was performed using the arrangement pattern 10, the flicker determination was “◯”.

  The array pattern 11 is a duty pattern with a duty ratio of 20%. The array pattern 11 includes five half-wave periods as one control section, and is composed of one on section and four off sections. Specifically, the first column is an on section, and the other is an off section. One control section of the array pattern 11 is 50 msec. When the lighting control of the heater was performed using the arrangement pattern 11, the flicker determination was “x”.

[Example of array pattern change]
When the lighting control of the first and second heaters 220 and 230 is performed using the arrangement patterns 1 to 11 shown in FIG. 3 as they are, the flicker regulation value may not be cleared depending on the combination of arrangement patterns. Therefore, in the present invention, in at least one heater, the duty ratio of the arrangement pattern is the same, and the arrangement of the on section and the off section is changed (made different) so as to satisfy the flicker regulation value. The flicker regulation value can be cleared for the two heaters 220 and 230 as a whole. Hereinafter, an example in which the flicker regulation value is not cleared in the combination of the arrangement patterns of the first and second heaters 220 and 230 will be described. In this example, when the arrangement numbers of the arrangement patterns of the first and second heaters 220 and 230 are different, the duty ratio is switched by a multiple of the arrangement number that is the least common multiple of both arrangement numbers.

  FIG. 5A shows flicker measurement of the first and second heaters 220 and 230 when both the first and second heaters 220 and 230 are turned on by the array pattern 2 having a duty ratio of 85.71%. Values and array patterns are shown. As shown in FIG. 5A, when the arrangement patterns 2 and 2 are combined, the flicker measurement value becomes “1.973” and the flicker regulation value cannot be cleared. This is because the flicker becomes large when the first and second heaters 220 and 230 are simultaneously turned off.

  Therefore, in the present invention, the flicker regulation value is cleared by changing the arrangement of the on section and the off section of at least one arrangement pattern 2 of the first and second heaters 220 and 230. FIG. 5B shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when the arrangement of the ON section and the OFF section of the arrangement pattern 2 of the first heater 220 is changed. .

  As shown in FIG. 5B, the off section of the array pattern 2 of the first heaters 220 is not located at the same position as the off section of the array pattern 2 of the second heaters 230, that is, the first and second The arrangement of the arrangement pattern 2 of the first heater 220 is changed with the same duty ratio so that the heaters 220 and 230 of the first heater 220 are not simultaneously turned off. For example, the off section in the second row of the arrangement pattern 2 of the first heaters 220 is changed to the on section. As a result, the flicker measurement value becomes “0.553”, and the flicker regulation value can be cleared even by the combination of the arrangement patterns 2 and 2.

  FIG. 6A shows the first case where the first heater 220 is turned on by the array pattern 3 having a duty ratio of 81.8% and the second heater 230 is turned on by the array pattern 4 having a duty ratio of 80%. The flicker measurement value and arrangement pattern of the 1st and 2nd heaters 220 and 230 are shown. As shown in FIG. 6A, when the arrangement patterns 3 and 4 are combined, the flicker measurement value is “0.95” and the flicker regulation value cannot be cleared. This is because the flicker becomes large when the first and second heaters 220 and 230 are simultaneously turned off.

  FIG. 6B shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when the arrangement of the ON section and the OFF section of the arrangement pattern 3 of the first heater 220 is changed. . As shown in FIG. 6B, the off section of the array pattern 3 of the first heaters 220 is not located at the same position as the off section of the array pattern 4 of the second heaters 230, that is, the first and first The arrangement of the arrangement pattern 3 of the first heater 220 is changed with the same duty ratio so that the two heaters 220 and 230 are not turned off simultaneously. For example, the off section in the second row of the arrangement pattern 3 of the first heaters 220 is changed to the on section. As a result, the number of arrays that are simultaneously turned on simultaneously can be reduced, so that the flicker measurement value is “0.698”, and the flicker regulation value can be cleared even by a combination of the array patterns 3 and 4.

  FIG. 7A shows the case where the first heater 220 is turned on by the array pattern 3 having a duty ratio of 81.8%, and the second heater 230 is turned on by the array pattern 8 having a duty ratio of 55.56%. 2 shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 in FIG. As shown in FIG. 7A, when the arrangement patterns 3 and 8 are combined, the flicker measurement value is “1.098”, and the flicker regulation value cannot be cleared. This is because the flicker increases when the first and second heaters 220 and 230 are simultaneously turned off or continuously turned on simultaneously.

  FIG. 7B shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when the arrangement of the ON section and the OFF section of the arrangement pattern 8 of the second heater 230 is changed. . As shown in FIG. 7B, the ON section of the array pattern 8 of the second heater 230 is not continuously located at the same position as the ON section of the array pattern 3 of the first heater 220, that is, the first section And the arrangement of the arrangement pattern 8 of the second heater 230 is changed to have the same duty ratio so that the second heaters 220 and 230 are not turned on simultaneously. For example, the on section of the fourth row and the fifth row of the arrangement pattern 8 of the second heater 230 is changed to the off section.

  Further, as shown in FIG. 7B, the off section of the array pattern 8 of the second heater 230 is not located at the same position as the off section of the array pattern 3 of the first heater 220, that is, the first section And the arrangement of the arrangement pattern 8 of the second heater 230 is changed to have the same duty ratio so that the second heaters 220 and 230 are not simultaneously turned off. Specifically, the 18th row off section of the array pattern 8 of the second heater 230 is changed to an on section. As a result, the flicker measurement value becomes “0.543”, and the flicker regulation value can be cleared even when the arrangement patterns 3 and 8 are combined.

  FIG. 8A shows the first case where the first heater 220 is turned on by the array pattern 3 having a duty ratio of 81.8% and the second heater 230 is turned on by the array pattern 11 having a duty ratio of 20%. The flicker measurement value and arrangement pattern of the 1st and 2nd heaters 220 and 230 are shown. As shown in FIG. 8A, when the arrangement patterns 3 and 11 are combined, the flicker measurement value is “1.059”, and the flicker regulation value cannot be cleared. This is because the flicker becomes large when the first and second heaters 220 and 230 are simultaneously turned off.

  FIG. 8B shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when the arrangement of the ON section and the OFF section of the arrangement pattern 11 of the second heater 230 is changed. . As shown in FIG. 8B, the off section of the array pattern 11 of the second heater 230 is not located at the same position as the off section of the array pattern 3 of the first heater 220, that is, the first and second The arrangement of the arrangement pattern 11 of the second heater 230 is changed with the same duty ratio so that the heaters 220 and 230 of the second heater 230 do not turn off simultaneously. Specifically, the off section in the second row of the arrangement pattern 11 of the second heater 230 is changed to the on section. As a result, the flicker measurement value becomes “0.483”, and the flicker regulation value can be cleared even when the arrangement patterns 3 and 11 are combined.

  FIG. 9A shows flicker measurement values of the first and second heaters 220 and 230 when both the first and second heaters 220 and 230 are turned on by the array pattern 4 having a duty ratio of 80%. The arrangement pattern is shown. As shown in FIG. 9A, when the arrangement patterns 4 and 4 are combined, the flicker measurement value is “1.901” and the flicker regulation value cannot be cleared. This is because the flicker increases when the first and second heaters 220 and 230 are simultaneously turned off.

  FIG. 9B shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when the arrangement of the ON section and the OFF section of the arrangement pattern 4 of the first heater 220 is changed. . As shown in FIG. 9B, the off section of the array pattern 4 of the first heater 220 is not located at the same position as the off section of the array pattern 4 of the second heater 230, that is, the first and second The arrangement of the arrangement pattern 4 of the first heater 220 is changed with the same duty ratio so that the heaters 220 and 230 of the first heater 220 are not turned off simultaneously. Specifically, the second row of the array pattern 4 of the first heaters 220 is changed from the off section to the on section. As a result, it is possible to reduce the number of arrays that are continuously turned on at the same time, so that the flicker measurement value is “0.451”, and the flicker regulation value can be cleared even by a combination of the array patterns 4 and 4.

  FIG. 10A shows the first case where the first heater 220 is turned on by the array pattern 4 having a duty ratio of 80% and the second heater 230 is turned on by the array pattern 8 having a duty ratio of 55.56%. The flicker measurement value and arrangement pattern of the 1st and 2nd heaters 220 and 230 are shown. As shown in FIG. 10A, when the arrangement patterns 4 and 8 are combined, the flicker measurement value is “1.03”, and the flicker regulation value cannot be cleared. This is because the flicker increases when the first and second heaters 220 and 230 are simultaneously turned off or continuously turned on simultaneously.

  FIG. 10B shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when the arrangement of the ON section and the OFF section of the arrangement pattern 8 of the second heater 230 is changed. . As shown in FIG. 10B, the off section of the array pattern 8 of the second heater 230 is not located at the same position as the off section of the array pattern 4 of the first heater 220, that is, the first and second The arrangement of the arrangement pattern 8 of the second heater 230 is changed with the same duty ratio so that the heaters 220 and 230 of the second heater 230 do not turn off simultaneously. For example, the off section in the 12th column of the array pattern 8 of the second heater 230 is changed to the on section.

  Further, the ON section of the arrangement pattern 8 of the second heater 230 is not continuously located at the same position as the ON section of the arrangement pattern 4 of the first heater 220, that is, the first and second heaters 220 and 230. The arrangement of the arrangement pattern 8 of the second heater 230 is changed with the same duty ratio so that the two are not simultaneously turned on. For example, the on section of the fourth row and the fifth row of the arrangement pattern 8 of the second heater 230 is changed to the off section. As a result, the flicker measurement value becomes “0.548”, and the flicker regulation value can be cleared even when the arrangement patterns 4 and 8 are combined.

  FIG. 11A shows the first and second cases in which the first heater 220 is turned on by the array pattern 4 having a duty ratio of 80% and the second heater 230 is turned on by the array pattern 9 having a duty ratio of 40%. The flicker measurement value and arrangement pattern of the second heaters 220 and 230 are shown. As shown in FIG. 11A, when the arrangement patterns 4 and 9 are combined, the flicker measurement value becomes “0.984” and the flicker regulation value cannot be cleared. This is because the flicker becomes large when the first and second heaters 220 and 230 are simultaneously turned off.

  FIG. 11B shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when the arrangement of the ON section and the OFF section of the arrangement pattern 4 of the first heater 220 is changed. . As shown in FIG. 11B, the off section of the array pattern 4 of the first heaters 220 is not located at the same position as the off section of the array pattern 9 of the second heaters 230, that is, the first and second The arrangement of the arrangement pattern 4 of the first heater 220 is changed with the same duty ratio so that the heaters 220 and 230 of the first heater 220 are not turned off simultaneously. For example, the off section in the second row of the array pattern 4 of the first heaters 220 is changed to the on section. As a result, the number of arrays with the same ON interval can also be reduced, so that the flicker measurement value is “0.638”, and the flicker regulation value can be cleared even with a combination of the array patterns 4 and 9.

  FIG. 12A shows the case where the first heater 220 is turned on by the array pattern 5 having a duty ratio of 71.43% and the second heater 230 is turned on by the array pattern 8 having a duty ratio of 55.56%. 2 shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 in FIG. As shown in FIG. 12A, when the arrangement patterns 5 and 8 are combined, the flicker measurement value becomes “0.982” and the flicker regulation value cannot be cleared. This is because the flicker increases when the first and second heaters 220 and 230 are simultaneously turned off or continuously turned on simultaneously.

  FIG. 12B shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when the arrangement of the ON section and the OFF section of the arrangement pattern 8 of the second heater 230 is changed. . As shown in FIG. 12B, the off section of the arrangement pattern 8 of the second heater 230 is not located at the same position as the off section of the arrangement pattern 5 of the first heater 220, that is, the first and second The arrangement of the arrangement pattern 8 of the second heater 230 is changed with the same duty ratio so that the heaters 220 and 230 of the second heater 230 do not turn off simultaneously. For example, the off section in the 12th column of the array pattern 8 of the second heater 230 is changed to the on section.

  Further, the ON section of the array pattern 8 of the second heater 230 is not continuously located at the same position as the ON section of the array pattern 5 of the first heater 220, that is, the first and second heaters 220 and 230. The arrangement pattern 8 of the second heater 230 is changed so as not to be turned on simultaneously. For example, the on section of the 10th column of the arrangement pattern 8 of the second heater 230 is changed to the off section. As a result, the flicker measurement value becomes “0.502”, and the flicker regulation value can be cleared even when the arrangement patterns 5 and 8 are combined.

  FIG. 13A shows the case where the first heater 220 is turned on by the array pattern 7 having a duty ratio of 57.14% and the second heater 230 is turned on by the array pattern 8 having a duty ratio of 55.56%. 2 shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 in FIG. As shown in FIG. 13A, when the arrangement patterns 7 and 8 are combined, the flicker measurement value becomes “0.984” and the flicker regulation value cannot be cleared. This is because the flicker increases when the first and second heaters 220 and 230 are simultaneously turned off or continuously turned on simultaneously.

  FIG. 13B shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when the arrangement of the ON section and the OFF section of the arrangement pattern 8 of the second heater 230 is changed. . As shown in FIG. 13B, the off section of the array pattern 8 of the second heater 230 is not located at the same position as the off section of the array pattern 7 of the first heater 220, that is, the first and second The arrangement of the second heaters 230 is changed to have the same duty ratio so that the heaters 220 and 230 of the first and second heaters 230 and 230 do not turn off simultaneously. For example, the off section in the ninth row of the array pattern 8 of the second heater 230 is changed to the on section.

  Further, the ON section of the array pattern 8 of the second heater 230 is not continuously located at the same position as the ON section of the array pattern 7 of the first heater 220, that is, the first and second heaters 220 and 230. The arrangement of the arrangement pattern 8 of the second heater 230 is changed with the same duty ratio so that the two are not simultaneously turned on. For example, the 10th and 11th rows of the on-section of the array pattern 8 of the second heater 230 are changed to off-sections. As a result, the flicker measurement value becomes “0.719”, and the flicker regulation value can be cleared even when the arrangement patterns 7 and 8 are combined.

  FIG. 14A shows the first case where the first heater 220 is turned on by the array pattern 8 having a duty ratio of 55.56% and the second heater 230 is turned on by the array pattern 9 having a duty ratio of 40%. The flicker measurement value and arrangement pattern of the 1st and 2nd heaters 220 and 230 are shown. As shown in FIG. 14A, when the arrangement patterns 8 and 9 are combined, the flicker measurement value is “1.228”, and the flicker regulation value cannot be cleared. This is because the flicker increases when the first and second heaters 220 and 230 are turned on or off at the same time.

  FIG. 14B shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when the arrangement of the ON section and the OFF section of the arrangement pattern 8 of the first heater 220 is changed. . As shown in FIG. 14B, the ON section of the array pattern 8 of the first heater 220 is not located at the same position as the ON section of the array pattern 9 of the second heater 230, that is, the first and second The arrangement of the arrangement pattern 8 of the first heater 220 is changed with the same duty ratio so that the heaters 220 and 230 of the first heater 220 are not turned on simultaneously. For example, the on section in the first row of the array pattern 8 of the first heaters 220 is changed to the off section.

  Further, the off section of the arrangement pattern 8 of the first heater 220 is not located at the same position as the off section of the arrangement pattern 9 of the second heater 230, that is, the first and second heaters 220 and 230 are turned off simultaneously. The arrangement of the arrangement pattern 8 of the first heater 220 is changed so that the duty ratio is the same. For example, the off section in the eighth row of the array pattern 8 of the first heaters 220 is changed to the on section. Furthermore, by changing the off section of the 17th column of the arrangement pattern 8 to the on section, it is possible to prevent the off sections from being continuously located at the same position. As a result, the flicker measurement value becomes “0.782”, and the flicker regulation value can be cleared even when the arrangement patterns 8 and 9 are combined.

  FIG. 15A illustrates the first case where the first heater 220 is turned on by the array pattern 8 having a duty ratio of 55.56% and the second heater 230 is turned on by the array pattern 11 having a duty ratio of 20%. The flicker measurement value and arrangement pattern of the 1st and 2nd heaters 220 and 230 are shown. As shown in FIG. 15A, when the arrangement patterns 8 and 11 are combined, the flicker measurement value is “1.356”, and the flicker regulation value cannot be cleared. This is because the flicker increases when the first and second heaters 220 and 230 are simultaneously turned on or continuously turned off simultaneously.

  FIG. 15B shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when the arrangement of the ON section and the OFF section of the arrangement pattern 8 of the first heater 220 is changed. . As shown in FIG. 15B, the ON section of the array pattern 8 of the first heater 220 is not located at the same position as the ON section of the array pattern 11 of the second heater 230, that is, the first and second The arrangement of the arrangement pattern 8 of the first heater 220 is changed with the same duty ratio so that the heaters 220 and 230 of the first heater 220 are not turned on simultaneously. For example, the on section in the first row of the array pattern 8 of the first heaters 220 is changed to the off section.

  Further, the off section of the array pattern 8 of the first heater 220 is not continuously located at the same position as the off section of the array pattern 11 of the second heater 230, that is, the first and second heaters 220 and 230. The arrangement of the arrangement pattern 8 of the first heaters 220 is changed to have the same duty ratio so that they are not simultaneously turned off. For example, the off section in the eighth row of the array pattern 8 of the first heaters 220 is changed to the on section. As a result, the flicker measurement value becomes “0.728”, and the flicker regulation value can be cleared even when the arrangement patterns 8 and 11 are combined.

  FIG. 16A shows flicker measurement values of the first and second heaters 220 and 230 when both the first and second heaters 220 and 230 are turned on by the array pattern 9 having a duty ratio of 40%. The arrangement pattern is shown. As shown in FIG. 16A, when the arrangement patterns 9 and 9 are combined, the flicker measurement value becomes “0.901” and the flicker regulation value cannot be cleared. This is because the flicker increases when the first and second heaters 220 and 230 are simultaneously turned on or continuously turned off simultaneously.

  FIG. 16B shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when the arrangement of the ON section and the OFF section of the arrangement pattern 8 of the first heater 220 is changed. . As shown in FIG. 16B, the ON section of the array pattern 9 of the first heater 220 is not located at the same position as the ON section of the array pattern 9 of the second heater 230, that is, the first and second The arrangement of the arrangement pattern 9 of the first heater 220 is changed with the same duty ratio so that the heaters 220 and 230 of the first heater 220 are not turned on simultaneously. For example, the on section in the first row of the array pattern 9 of the first heaters 220 is changed to the off section.

  Further, the off section of the arrangement pattern 9 of the first heater 220 is not continuously located at the same position as the off section of the arrangement pattern 9 of the second heater 230, that is, the first and second heaters 220 and 230. The arrangement of the arrangement pattern 9 of the first heaters 220 is changed with the same duty ratio so that the two are not simultaneously turned off. For example, the off section in the second row of the array pattern 9 of the first heaters 220 is changed to the on section. As a result, the flicker measurement value becomes “0.714”, and the flicker regulation value can be cleared even when the arrangement patterns 9 and 9 are combined.

[Table configuration example]
The image forming apparatus 100 includes a table TB1 that stores combinations of arrangement patterns of the first and second heaters 220 and 230 that can clear flicker measurement values. For example, as a combination of array patterns, among the combinations of the array patterns 1 to 11 of the first and second heaters 220 and 230 shown in FIG. 3, a combination of array patterns that can originally clear the flicker regulation value, As illustrated in FIG. 5 to FIG. 16, there are combinations of arrangement patterns in which the arrangement of the on section and the off section is changed so that the flicker specified value can be cleared. The table TB1 is created, for example, before shipment of the image forming apparatus 100, and is stored in the storage unit 252.

  FIG. 17 shows a summary of flicker measurement values when the first heater 220 is turned on by the array patterns 3 to 7 and the second heater 230 is turned on by the array patterns 5 to 11. The upper part of each enclosed part in FIG. 17 represents the flicker measurement value that could not clear the flicker regulation value when the arrangement pattern of the first and second heaters 220 and 230 was combined, and the lower part represents the first heater 220. The flicker regulation value in which the flicker regulation value is cleared by changing the arrangement pattern such as. Note that other arrangement pattern combinations are omitted for convenience.

  FIG. 18 shows a configuration of a table TB2 that stores a combination of an array pattern that clears the flicker regulation value among the flicker measurement values of the first and second heaters 220 and 230 shown in FIG. 17 and the flicker measurement value in association with each other. An example is shown. FIG. 18 shows flicker measurement values when the first heater 220 is turned on by the array patterns 3 to 7 and the second heater 230 is turned on by the array patterns 5 to 11. FIG. It is assumed that flicker measurement values when the first and second heaters 220 and 230 are turned on by other combinations of arrangement patterns are also stored in the table TB2.

  The table TB2 is a table that is referred to when determining the arrangement pattern of the first and second heaters 220 and 230 when the flicker priority mode is selected. The table TB2 is created, for example, before shipment of the image forming apparatus 100, and is stored in the storage unit 252 in advance. The table TB2 can be configured as one table in association with the pattern information of the table TB1, or can be configured separately in association with the table TB1.

[Operation example of image forming apparatus]
Next, an operation example of the image forming apparatus 100 including the fixing device 200 during the fixing process will be described. FIG. 19 is a flowchart illustrating an example of the operation of the image forming apparatus 100 during the fixing process.

  As shown in FIG. 19, in step S <b> 10, for example, when an instruction for image forming processing is received by the operation display unit 70 or the like, fixing processing including temperature control of the first and second heaters 220 and 230 by the fixing device 200 is performed. Be started.

  In step S <b> 20, the control unit 250 acquires the measured temperature of the first heater 220 from the temperature sensor 222 and acquires the measured temperature of the second heater 230 from the temperature sensor 232. The control unit 250 stores the acquired measured temperatures in the storage unit 252.

  In step S <b> 30, the control unit 250 determines the duty ratio for turning on the first heater 220 based on the difference between the acquired measured temperature of the first heater 220 and the preset target temperature of the first heater 220. Is calculated. Similarly, the control unit 250 determines the duty ratio for turning on the second heater 230 based on the difference between the acquired measured temperature of the second heater 230 and a preset target temperature of the second heater 230. Is calculated. Note that the duty ratios of the first and second heaters 220 and 230 can be calculated by a method such as PI control using a past temperature history.

  In step S <b> 40, the control unit 250 selects and sets the optimal duty ratio of the first heater 220 corresponding to the set lighting mode based on the calculated duty ratio of the first heater 220. Specifically, when the calculation result of the duty ratio of the first heater 220 is “60%”, for example, referring to the table shown in FIG. 18, the duty ratio “60%” is the duty ratio “66.67%”. And the duty ratio “57.14%”, it is necessary to select one of the duty ratios. When the flicker priority mode is set as the lighting mode, the control unit 250 selects the duty ratio with the smaller flicker measurement value out of the two duty ratios “66.67%” and “57.14%”. Here, it is assumed that the duty ratio during the lighting control of the second heater 230 is set to, for example, “40%” based on the calculation result. The control unit 250 refers to the table TB2 of FIG. 18, the flicker measurement value of the duty ratio “66.67%” is “0.551”, and the flicker regulation value of the duty ratio “57.14%” is “0”. .708 ", a duty ratio" 66.67% "with a small flicker measurement value is selected. In this way, the controller 250 sets “66.67%” as the duty ratio when turning on the first heater 220 and “40%” as the duty ratio when turning on the second heater 230. Set.

  In step S50, the control unit 250 controls lighting of the first and second heaters 220 and 230 based on the set duty ratio. Specifically, the control unit 250 reads an array pattern corresponding to the set duty ratio “66.67%” of the first heater 220 from the table TB1, and switches the switching unit 260 based on the read array pattern. By controlling, lighting control of the first heater 220 is performed. Similarly, the control unit 250 reads an array pattern corresponding to the set duty ratio “40%” of the second heater 230 from the table TB1, and controls the switching unit 270 to switch based on the read array pattern. The lighting control of the second heater 230 is performed.

  As described above, according to the first embodiment, even if there is a combination of arrangement patterns that cannot clear the flicker regulation value, the ON interval of at least one arrangement pattern of the first and second heaters 220 and 230. In addition, since the arrangement of the off section is changed to clear the flicker specified value and the lighting control is performed using the changed arrangement pattern, the flicker regulation value can be surely cleared. In addition, deterioration of temperature ripple can be prevented.

  Further, according to the first embodiment, since an optimum combination of arrangement patterns according to the flicker priority mode can be selected, the flicker regulation value can be cleared more reliably.

  In the first embodiment, the arrangement pattern is changed so that the on and off sections of the first and second heaters 220 and 230 are not in the same position, and the on and off sections are continuously the same. Change the array pattern so that it does not become a position. Thereby, since rapid fluctuations such as the voltages of the first and second heaters 220 and 230 can be suppressed, the occurrence of flicker can be effectively suppressed.

  Furthermore, conventionally, an expensive resistor module may be required for the flicker regulation. However, according to the first embodiment, since the flicker countermeasure can be taken by changing the arrangement of the arrangement pattern, Modules and other countermeasure parts are not required.

<Second Embodiment>
In the first embodiment, the method for determining the duty ratio of the first heater 220 and the like when the flicker priority mode is selected has been described. However, in the second embodiment, the temperature ripple mode is selected. A method for determining the duty ratio of the first heater 220 will be described. Other configurations and operations of the image forming apparatus 100 and the like are the same as those in the first embodiment, and therefore, common constituent elements are denoted by the same reference numerals and detailed description thereof is omitted. Specifically, since only the control content of step S40 of FIG. 19 of the first embodiment is different, only step S40 will be described below.

  If the calculation result of the duty ratio of the first heater 220 is “60%” in step S30 of FIG. 19, referring to the table TB2 shown in FIG. 18, the duty ratio “60%” is the duty ratio “66.67%”. ”And the duty ratio“ 57.14% ”, it is necessary to select any one of the duty ratios. When the temperature ripple priority mode is set as the lighting mode, the control unit 250 selects a duty ratio with a smaller temperature ripple out of the two duty ratios “66.67%” and “57.14%”. . Here, it is assumed that the duty ratio at the time of lighting control of the second heater 230 is set to “40%”, for example.

  In the temperature ripple priority mode, the lighting control can be controlled more stably and the temperature ripple can be improved by selecting a duty ratio having a value close to the calculated duty ratio “60%”. Therefore, the control unit 250 selects “57.14%” as the duty ratio. In this way, the controller 250 sets “57.14%” as the duty ratio when turning on the first heater 220 and “40%” as the duty ratio when turning on the second heater 230. Set.

  As described above, according to the second embodiment, the same operational effects as those of the first embodiment can be obtained. In addition, according to the second embodiment, since an optimal combination of arrangement patterns according to the temperature ripple priority mode can be selected, the temperature ripple can be improved more reliably.

<Third Embodiment>
In the first embodiment, the method of determining the duty ratio of the first heater 220 and the like when the flicker priority mode is selected has been described. In the third embodiment, both the flicker priority mode and the temperature ripple mode are described. A method for determining the duty ratio of the first heater 220 or the like when is selected will be described. Other configurations and operations of the image forming apparatus 100 and the like are the same as those in the first embodiment, and therefore, common constituent elements are denoted by the same reference numerals and detailed description thereof is omitted. Specifically, since only the control content of step S40 of FIG. 19 of the first embodiment is different, only step S40 will be described below.

  In step S30 of FIG. 19, for example, “80%” is calculated as the duty ratio of the first heater 220, and “70%” is calculated as the duty ratio of the second heater 230, for example. Referring to the table TB2, the duty ratio “80%” of the first heater 220 is between the duty ratio “81.3%” and the duty ratio “80%”, and the duty ratio “70” of the first heater 220 is set. % ”Is between the duty ratio“ 71.43% ”and the duty ratio“ 66.67% ”. Therefore, the control unit 250 needs to select one combination of duty ratios from the four combinations of duty ratios.

  Here, with respect to the calculation result “80%” of the duty ratio of the first heater 220, there is no deviation at the duty ratio “80%”, and the deviation is about 2% at the duty ratio “81.3%”. Further, with respect to the calculation result “70%” of the duty ratio of the second heater 230, the deviation is about 2% at the duty ratio “71.43%”, and the deviation is about 5% at the duty ratio “66.67%”. It becomes.

  Since both the flicker priority mode and the temperature ripple priority mode are selected as the lighting mode, the controller 250 has a small flicker measurement value among the four sets of duty ratios, and the calculated first and second heaters. A duty ratio that is close to the duty ratio of 220 and 230 is selected. The flicker measurement values of the four sets of duty ratios are “0.879”, “0.804”, “0.818”, “0.745” as shown in the table TB2 (boxed portion) shown in FIG. is there.

  When “80%” is selected as the duty ratio of the first heater 220, it is a value close to the duty ratio calculated in the first heater 220 (no deviation) and flicker measurement values of four sets of duty ratios Among them, “0.804” and “0.745” having a small value can be selected. Therefore, the controller 250 first selects and sets “80%” as the duty ratio of the first heater 220.

  Subsequently, when the flicker measurement value “0.804” in the case of the duty ratio “71.43” is compared with the flicker measurement value “0.745” in the case of the duty ratio “66.67”, the flicker measurement value is obtained. “0.745” has an improvement rate of 7% compared to “0.804”. For this reason, the control unit 250 selects and sets “66.67%” as the duty ratio of the second heater 230, which decreases the flicker measurement value.

  Next, a case where the calculation result of the duty ratio of the first heater 220 is “80%” and the calculation result of the duty ratio of the second heater 230 is “50%” will be described. Referring to the table TB2, the duty ratio “80%” of the first heater 220 is between the duty ratio “81.3%” and the duty ratio “80%”, and the duty ratio “50” of the second heater 230 is set. % ”Is between the duty ratio“ 55.56% ”and the duty ratio“ 40% ”. Therefore, the control unit 250 needs to select one combination of duty ratios from the four combinations of duty ratios.

  Here, with respect to the calculation result “80%” of the duty ratio of the first heater 220, there is no deviation at the duty ratio “80%”, and the deviation is about 2% at the duty ratio “81.3%”. Further, with respect to the calculation result “50%” of the duty ratio of the second heater 230, the deviation is about 10% at the duty ratio “55.56%”, and the deviation is about 20% at the duty ratio “40%”. .

  Since both the flicker priority mode and the temperature ripple priority mode are selected as the lighting mode, the controller 250 has a small flicker measurement value among the four sets of duty ratios, and the calculated first and second heaters. A duty ratio that is close to the duty ratio of 220 and 230 is selected. The flicker measurement values of the four sets of duty ratios are “0.543”, “0.548”, “0.9”, “0.638” as shown in the table TB2 (gray colored portion) shown in FIG. It is.

  When “55.56%” is selected as the duty ratio of the second heater 230, the value is close to the calculated duty ratio of the second heater 230, and is a value among the flicker measurement values of the four sets of duty ratios. “0.548” and “0.543” can be selected. Therefore, the control unit 250 first selects “55.56%” as the duty ratio of the second heater 230.

  Subsequently, the flicker measurement value “0.543” when the duty ratio of the first heater 220 is “81.8%” and the flicker measurement value “0.548” when the duty ratio is “80%” are compared. Since the improvement rate of the flicker measurement value is almost equal, either duty ratio may be selected. For example, the control unit 250 selects and sets “81.8%” as the duty ratio of the first heater 220 when the flicker is particularly prioritized, and particularly when the temperature ripple is prioritized. As a duty ratio of 220, “80%” can be selected and set.

  As described above, according to the third embodiment, the same operational effects as those of the first embodiment can be obtained. Further, according to the third embodiment, since it is possible to select an optimum combination of arrangement patterns according to the flicker priority mode and the temperature ripple priority mode, it is possible to improve both the flicker priority mode and the temperature ripple more reliably. Can be achieved.

  It should be noted that the technical scope of the present invention is not limited to the above-described embodiments, and includes those in which various modifications are made to the above-described embodiments without departing from the spirit of the present invention.

  For example, in the above embodiment, the flicker regulation value is cleared by changing the arrangement pattern of one of the first and second heaters 220 and 230. However, the present invention is not limited to this. Absent. For example, the flicker regulation value may be cleared by changing the arrangement pattern of both the first and second heaters 220 and 230. If there are three or more heaters, the arrangement pattern of one heater may be changed, or the flicker regulation value may be cleared by changing the arrangement pattern of two or more heaters. .

  Moreover, in the said embodiment, although the arrangement pattern of the 1st and 2nd heaters 220 and 230 was determined using the table TB1 and TB2 which memorize | stored the combination of the arrangement pattern and the flicker measurement value, it is limited to this. There is nothing. For example, a sensor that measures flicker of an electronic device such as a lighting device may be provided, and the arrangement pattern of the first and second heaters 220 and 230 may be determined based on the flicker measurement result of the sensor. Specifically, the control unit 250 acquires the flicker measurement value from the sensor, and determines whether or not the acquired flicker measurement value clears the flicker regulation value. When the control unit 250 determines that the flicker regulation value is not cleared, the control unit 250 sets the arrangement of the on section and the off section of the arrangement pattern shown in FIG. 3 in the duty of at least one of the first and second heaters 220 and 230. The ratio is set to be the same so that the flicker regulation value is cleared, and lighting control is performed based on the changed arrangement pattern. On the other hand, when it is determined that the flicker regulation value is cleared, the control unit 250 controls the lighting of the first and second heaters 220 and 230 based on a combination of preset arrangement patterns (for example, the table TB1) shown in FIG. I do. The method for determining the duty ratio and the arrangement pattern is the same as in the above-described embodiment.

  In addition, when changing the arrangement of the arrangement pattern, it is preferable to consider the arrangement of the arrangement pattern of the next period. Further, when changing the arrangement pattern, it is changed so as to include at least one of the on-interval and the off-interval not being simultaneously performed and the off-interval and the on-interval not being simultaneously performed simultaneously.

  Furthermore, in the above-described embodiment, the example in which the present invention is applied to the image forming apparatus 100 that forms a color image has been described.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 200 Fixing apparatus 220 1st heater 222 Temperature sensor (temperature detection part)
230 Second heater 232 Temperature sensor (temperature detector)
250 Control unit 260, 270 Switching unit TB1, TB2 Table

Claims (11)

Multiple heaters to fix the image on the paper,
A switching unit that switches between an on state that connects the plurality of heaters and the AC power source and an off state that releases the connection between the plurality of heaters and the AC power source;
A control unit that performs lighting control of the plurality of heaters by switching the switching unit according to an array pattern of an on section and an off section in units of a half-wave period of the AC power supply,
The controller, when simultaneously controlling lighting of each of the plurality of heaters with the array pattern having a predetermined duty ratio, satisfies a flicker regulation value set with the same duty ratio of the array pattern in at least one heater. A lighting device that performs lighting control using an arrangement pattern in which the arrangement of the on section and the off section is changed. The fixing device according to claim 1, further comprising a table that stores pattern information obtained by combining array patterns of duty ratios for each of the plurality of heaters. The fixing device according to claim 2, wherein flicker measurement values are associated with each pattern information and stored in the table. A temperature detection unit for detecting the temperature of the heater;
The control unit selects from the table a duty ratio having a small flicker measurement value among a plurality of duty ratios corresponding to the duty ratio of the heater calculated from the heater temperature information detected by the temperature detection unit. The fixing device according to claim 3. A temperature detection unit for detecting the temperature of the heater;
The fixing device according to claim 3, wherein the control unit selects a duty ratio closest to the duty ratio of the heater calculated from the temperature information of the heater detected by the temperature detection unit from the table. . A temperature detection unit for detecting the temperature of the heater;
The control unit has a small flicker measurement value among a plurality of duty ratios corresponding to the duty ratio of the heater calculated from the temperature information of the heater detected by the temperature detection unit, and the calculated duty ratio of the heater The fixing device according to claim 3, wherein a duty ratio close to is selected from the table. The fixing unit according to any one of claims 1 to 6, wherein the off section of the arrangement pattern of the one heater is arranged so as not to be in the same position as the off section of the arrangement pattern of the other heaters. apparatus. 8. The arrangement according to claim 1, wherein the off section of the arrangement pattern of the one heater is arranged so as not to be continuously located at the same position as the off section of the arrangement pattern of the other heaters. The fixing device described. 9. The fixing according to claim 1, wherein the ON section of the arrangement pattern of the one heater is arranged not to be in the same position as the ON section of the arrangement pattern of the other heaters. apparatus. The on section of the arrangement pattern of the one heater is arranged so as not to be continuously located at the same position as the on section of the arrangement pattern of the other heaters. The fixing device described. An image forming unit for forming an image on paper;
A fixing device for fixing the image formed by the image forming unit to the paper;
A control unit for controlling at least the fixing device,
The fixing device includes:
Multiple heaters to fix the image on the paper,
A switching unit that switches between an on state that connects the plurality of heaters and the AC power source and an off state that releases the connection between the plurality of heaters and the AC power source,
The control unit performs lighting control of the plurality of heaters by switching the switching unit according to an arrangement pattern of an on section and an off section in units of half-wave periods of the AC power supply, and each of the plurality of heaters is set to be predetermined. When the lighting control is performed simultaneously with the arrangement pattern of the duty ratio of at least one heater, the arrangement of the ON section and the OFF section is changed so as to satisfy the flicker regulation value set with the same duty ratio of the array pattern. An image forming apparatus that performs lighting control using an array pattern.