JP6269280B2 - Fixing apparatus and image forming apparatus - Google Patents

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 with an array pattern in units of half waves in each heater, but it is assumed that an array pattern advantageous to the flicker regulation value is used. However, if the timing for switching the arrangement pattern of a plurality of heaters is incorrect, the flicker regulation value may not be cleared.

  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 problems, a 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, the plurality of heaters, and the AC power source. A plurality of heaters by switching the switching unit according to an arrangement pattern composed of different arrangement numbers by on / off in units of half-wave periods of the AC power supply; A control unit that performs lighting control of the plurality of heaters, and the control unit controls the lighting of each of the plurality of heaters according to the arrangement pattern of a predetermined duty ratio. switching the arrangement pattern when the sequence of common multiple is completed, a reference of common multiple of the arrangement pattern of the plurality of heaters based Near your period, and is for the common multiple of long the arrangement pattern than the reference control period and control period.

The fixing device according to the present invention includes a plurality of heaters for fixing an image on a sheet, an ON state in which the plurality of heaters and an 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. A control unit that performs lighting control of the plurality of heaters by switching the switching unit according to an array pattern configured by a different number of arrays by ON / OFF with a half-wave period of the AC power supply as a unit. The control unit includes a first control unit, and a second control unit that performs control different from the control by the first control unit, and the second control unit includes: When the lighting control of each of the plurality of heaters is performed with the arrangement pattern having a predetermined duty ratio, the arrangement is performed when the arrangement of the common multiple of the arrangement number of the arrangement patterns of the plurality of heaters is completed. The pattern is switched, and the common multiple of the array pattern that is close to the reference control cycle and shorter than the reference control cycle among the common multiples of the array pattern of the plurality of heaters is set as the control cycle, or the plurality of heaters In the common multiple of the array pattern, it is determined whether the common multiple of the array pattern that is close to the reference control cycle and longer than the reference control cycle is used as the control cycle .

In addition, the control unit of the fixing device according to the present invention can change the control cycle according to a common multiple of the number of arrangements of the arrangement patterns of the plurality of heaters .

An image forming apparatus according to the present invention includes an image forming unit that forms an image on a sheet, a fixing unit that fixes an image formed by the image forming unit on the sheet, and a control unit that controls at least the fixing unit. The fixing device includes: a plurality of heaters for fixing an image on a sheet; an on state in which the plurality of heaters and an 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. A switching unit that switches between the switching unit and the control unit by switching the switching unit according to an array pattern composed of different array numbers by ON / OFF in units of half-wave periods of the AC power supply. When the lighting control of the plurality of heaters is performed and the lighting control of each of the plurality of heaters is performed according to the arrangement pattern having a predetermined duty ratio, the arrangement of the plurality of heaters is performed. The arrangement pattern is switched when the arrangement of the common multiple of the arrangement number of the patterns is completed, the reference multiple of the arrangement patterns of the plurality of heaters is close to a reference control cycle that is a reference, and longer than the reference control cycle The control pattern is a common multiple of the array pattern.

An image forming apparatus according to the present invention includes an image forming unit that forms an image on a sheet, a fixing unit that fixes an image formed by the image forming unit on the sheet, and a control unit that controls at least the fixing unit. The fixing device includes: a plurality of heaters for fixing an image on a sheet; an on state in which the plurality of heaters and an 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 a switching unit that switches between the first control unit and the second control unit that performs a control different from the control by the first control unit . The control unit of 2 performs lighting control of the plurality of heaters by switching the switching unit according to an arrangement pattern composed of different arrangement numbers by ON / OFF in units of half-wave periods of the AC power supply, No hi If lights controlling each by the arrangement pattern of a predetermined duty ratio of the terpolymer, switches the arrangement pattern when sequence SEQ number of common multiple of the arrangement pattern of the plurality of heaters is completed, the said plurality of heater Of the common multiples of the array pattern, the common multiple of the array pattern that is close to the reference control cycle that is the reference and shorter than the reference control cycle is used as the control cycle, or the reference control among the common multiples of the array pattern of the plurality of heaters It is determined whether the common multiple of the array pattern that is close to the cycle and longer than the reference control cycle is set as the control cycle .

  According to the present invention, since the arrangement pattern is switched when the arrangement of the common multiple of the arrangement number of the plurality of heater patterns is completed, the switching control that observes the arrangement of each arrangement pattern can be performed. Thereby, a flicker regulation value can be cleared reliably.

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 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 temperature control of the first and second heaters. 10 is a flowchart illustrating an operation example of the image forming apparatus during temperature control of the first and second heaters according to the second embodiment. FIG. 10 is a diagram for explaining a problem in fixing processing of an image forming apparatus according to a third embodiment. 6 is a flowchart illustrating an operation example of the image forming apparatus during temperature control of the first and second heaters. It is a figure which shows the block structural example of the image forming apparatus which concerns on 4th Embodiment. 6 is a flowchart illustrating an operation example of the image forming apparatus during temperature control of the first and second heaters. It is explanatory drawing in the case of determining the common multiple in which the common multiple of each arrangement pattern of the 1st and 2nd heaters is the closest to the reference control cycle as the next control cycle.

  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, the duplicate description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<First Embodiment>
[Configuration example of image forming apparatus]
First, the image forming apparatus 100A according to the present invention will be described. FIG. 1 shows an example of the configuration of an image forming apparatus 100A according to the present invention. As shown in FIG. 1, the image forming apparatus 100 </ b> A 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 Duplex 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 Device). ) 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 transported to the ADU 60 via the transport 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 100A including the fixing device 200. As illustrated in FIG. 2, the image forming apparatus 100 </ b> A includes an AC power supply 210, a fixing device 200, a control unit 250, and a storage unit 280. The AC power supply 210 is installed in an office or the like where the image forming apparatus 100A is installed, and supplies predetermined power to the image forming apparatus 100A including the fixing device 200.

  The fixing device 200 includes a first heater 220, a temperature sensor 222, a second heater 230, a temperature sensor 232, and switching units 260 and 270. The controller 250 can also be provided in the fixing device 200. 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 switches 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 switches 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 between a preset target temperature of the first and second heaters 220 and 230 and a measured temperature detected by the temperature sensors 222 and 232, and calculates the calculated temperature. On / off control of the first and second heaters 220 and 230 is performed based on the 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.

  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 280 is configured by, for example, a nonvolatile semiconductor memory, an HDD (Hard Disk Drive), or the like. The storage unit 280 stores a table TB (see FIG. 17) for storing combinations of arrangement patterns for controlling lighting of first and second heaters 220 and 230, which will be described later, and flicker measurement values.

[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 the current waveform in half-wave units and an example of flicker measurement values. 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”.

  In this example, lighting control is performed by combining the arrangement patterns 1 to 11 shown in FIG. 3 in the first and second heaters 220 and 230. However, when the lighting control is performed continuously by combining the array patterns 1 to 11 having different numbers of arrays, the flicker regulation value may not be cleared because the array pattern itself is changed due to the control cycle or the like. is there. Furthermore, even if the arrangement patterns 1 to 11 are combined, the flicker regulation value may not be cleared from the relationship between the arrangement positions of the on section and the off section.

  Therefore, in the present invention, at the timing when the arrangement of the common multiple of the arrangement numbers of the arrangement patterns of the first and second heaters 220 and 230 ends, the duty ratios of the first and second heaters 220 and 230 in the next control cycle are completed. Change the ratio. Further, in at least one heater, the duty ratio of the arrangement pattern is made the same, and the arrangement of the on section and the off section is changed so as to satisfy the flicker regulation value.

  Below, the case where lighting control of the 1st and 2nd heaters 220 and 230 is performed by the common multiple of the arrangement pattern will be described. FIGS. 5 to 16 show examples of combinations of arrangement patterns when the flicker restriction value can be cleared by changing the arrangement of the arrangement pattern in which the flicker restriction value cannot be cleared.

  FIG. 5 shows flicker measurement values and arrangement of the first and second heaters 220 and 230 when both the first and second heaters 220 and 230 are turned on by the arrangement pattern 2 having a duty ratio of 85.71%. The pattern is shown.

  As shown in FIG. 5, when both the first and second heaters 220 and 230 are controlled to be lit with the arrangement patterns 2 and 2, the arrangement numbers of the arrangement patterns 2 and 2 are “7”, and the least common multiple is “7”. Therefore, when combined lighting control by the first and second heaters 220 and 230 is performed, the lighting control is performed with a common multiple of “7”. When the arrangement pattern 2 or 2 is changed to an arrangement pattern having a different duty ratio, the arrangement pattern is switched to a different arrangement pattern at the timing when the arrangement of the common multiple of “7” is completed.

  Further, the off section of the arrangement pattern 2 of the first heater 220 is not in the same position as the off section of the arrangement pattern 2 of the second heater 230, that is, the first and second heaters 220 and 230 are turned off simultaneously. In order to avoid this, the arrangement of the arrangement pattern 2 of the first heaters 220 is changed with the same duty ratio. 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. 6 shows the first and second cases 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%. 2 shows flicker measurement values and arrangement patterns of the two heaters 220 and 230.

  As shown in FIG. 6, when the lighting of the first heater 220 is controlled by the array pattern 3 and the lighting of the second heater 230 is controlled by the array pattern 4, the number of arrays of the array pattern 3 is “11”. Since the number of arrays of pattern 4 is “5”, the least common multiple is “55”. Therefore, when combined lighting control by the first and second heaters 220 and 230 is performed, the lighting control is performed with a common multiple of “55”. When the arrangement pattern 3 or 4 is changed to an arrangement pattern having a different duty ratio, the arrangement pattern is switched to a different arrangement pattern at the timing when the arrangement of the common multiple of “55” is completed.

  Also, the duty ratio of the array pattern 3 of the first heater 220 is set so that the off section of the array pattern 3 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. Change as the same. As a result, the number of arrays that are simultaneously turned on can be reduced, and 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. 7 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 8 having a duty ratio of 55.56%. In addition, flicker measurement values and arrangement patterns of the second heaters 220 and 230 are shown.

  As shown in FIG. 7, when the lighting control of the first heater 220 is performed using the array pattern 3 and the lighting control of the second heater 230 is performed using the array pattern 8, the number of arrays of the array pattern 3 is “11”. Since the number of arrays of pattern 8 is “9”, the least common multiple is “99”. Therefore, when combined lighting control by the first and second heaters 220 and 230 is performed, the lighting control is performed with a common multiple of “99”. When the arrangement pattern 3 or 8 is changed to an arrangement pattern with a different duty ratio, the arrangement pattern is switched to a different arrangement pattern at the timing when the arrangement of the common multiple of “99” is completed.

  Further, the arrangement pattern 8 of the second heater 230 is set to duty so that 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 3 of the first heater 220. Change the ratio to be the same. Further, the duty ratio of the arrangement pattern 8 of the second heater 230 is set so that the off section of the arrangement pattern 8 of the second heater 230 is not in the same position as the off section of the arrangement pattern 3 of the first heater 220. Change as the same. As a result, the flicker measurement value becomes “0.543”, and the flicker regulation value can be cleared even by the combination of the array patterns 3 and 8.

  FIG. 8 shows the first and second cases 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%. 2 shows flicker measurement values and arrangement patterns of the two heaters 220 and 230.

  As shown in FIG. 8, when the first heater 220 is controlled to be turned on by the array pattern 3 and the second heater 230 is controlled to be turned on by the array pattern 11, the number of arrays of the array pattern 3 is “11”. Since the number of arrangements of the pattern 11 is “5”, the least common multiple is “55”. Therefore, when combined lighting control by the first and second heaters 220 and 230 is performed, the lighting control is performed with a common multiple of “55”. When the arrangement pattern 3 or 11 is changed to an arrangement pattern having a different duty ratio, the arrangement pattern is switched to a different arrangement pattern at the timing when the arrangement of the common multiple of “55” is completed.

  In addition, the arrangement of the arrangement pattern 11 of the second heater 230 has the same duty ratio so that the off section of the arrangement pattern 11 of the second heater 230 does not coincide with the off section of the arrangement pattern 3 of the first heater 220. Change as As a result, the flicker measurement value becomes “0.483”, and the flicker regulation value can be cleared even by the combination of the array patterns 3 and 11.

  FIG. 9 shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when both the first and second heaters 220 and 230 are turned on by the arrangement pattern 4 having a duty ratio of 80%. Show.

  As shown in FIG. 9, when both the first and second heaters 220 and 230 are controlled to be lit by the arrangement patterns 4 and 4, the arrangement numbers of the arrangement patterns 4 and 4 are “5”, respectively, and the least common multiple is “5”. Therefore, when combined lighting control by the first and second heaters 220 and 230 is performed, the lighting control is performed with a common multiple of “5”. When the arrangement pattern 4 or 4 is changed to an arrangement pattern having a different duty ratio, the arrangement pattern is switched to a different arrangement pattern at the timing when the arrangement of the common multiple of “5” is completed.

  Also, the duty ratio of the array pattern 4 of the first heater 220 is the same so that the off section of the array pattern 4 of the first heater 220 does not coincide with the off section of the array pattern 4 of the second heater 230. Change as As a result, it is possible to reduce the number of arrays that are continuously turned on simultaneously, 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. 10 shows the first and second cases when 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%. 2 shows flicker measurement values and arrangement patterns of the two heaters 220 and 230.

  As shown in FIG. 10, when the lighting control of the first heater 220 is performed using the array pattern 4 and the lighting control of the second heater 230 is performed using the array pattern 8, the number of arrays of the array pattern 4 is “5”. Since the number of arrays of pattern 8 is “9”, the least common multiple is “45”. Therefore, when combined lighting control is performed by the first and second heaters 220 and 230, the lighting control is performed with a common multiple of “45”. When changing from the arrangement patterns 4 and 8 to an arrangement pattern having a different duty ratio, the arrangement pattern is switched to a different arrangement pattern at the timing when the arrangement of the common multiple of “45” is completed.

  In addition, the arrangement of the arrangement pattern 8 of the second heater 230 has the same duty ratio so that the off section of the arrangement pattern 8 of the second heater 230 does not coincide with the off section of the arrangement pattern 4 of the first heater 220. Change as In addition, the arrangement of the arrangement pattern 8 of the second heater 230 is set to a duty so that 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. Change the ratio to be the same. 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. 11 shows the first and second cases 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 9 having a duty ratio of 40%. The flicker measurement value and arrangement pattern of the heaters 220 and 230 are shown.

  As shown in FIG. 11, when the lighting of the first heater 220 is controlled by the array pattern 4 and the lighting of the second heater 230 is controlled by the array pattern 9, the number of arrays of the array pattern 4 is “5”. Since the number of arrangements of the pattern 9 is “5”, the least common multiple is “5”. Therefore, when combined lighting control by the first and second heaters 220 and 230 is performed, the lighting control is performed with a common multiple of “5”. When changing from the arrangement patterns 4 and 9 to an arrangement pattern having a different duty ratio, the arrangement pattern is switched to a different arrangement pattern at the timing when the arrangement of the common multiple of “5” is completed.

  Also, the duty ratio of the array pattern 4 of the first heater 220 is the same so that the off section of the array pattern 4 of the first heater 220 does not coincide with the off section of the array pattern 9 of the second heater 230. Change as As a result, the flicker measurement value becomes “0.638”, and the flicker regulation value can be cleared even when the arrangement patterns 4 and 9 are combined.

  FIG. 12 shows the first 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%. In addition, flicker measurement values and arrangement patterns of the second heaters 220 and 230 are shown.

  As shown in FIG. 12, when the lighting control of the first heater 220 is performed by the array pattern 5 and the lighting control of the second heater 230 is performed by the array pattern 8, the number of arrays of the array pattern 5 is “7”. Since the number of arrays of pattern 8 is “9”, the least common multiple is “63”. Therefore, when combined lighting control by the first and second heaters 220 and 230 is performed, the lighting control is performed with a common multiple of “63”. When changing from the arrangement patterns 5 and 8 to an arrangement pattern having a different duty ratio, the arrangement pattern is switched to a different arrangement pattern at the timing when the arrangement of the common multiple of “63” is completed.

  In addition, the duty ratio of the array pattern 8 of the second heater 230 is the same so that the off section of the array pattern 8 of the second heater 230 does not coincide with the off section of the array pattern 5 of the first heater 220. Change as Further, the arrangement pattern 8 of the second heater 230 is changed so that 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 5 of the first heater 220. 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. 13 shows the first 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%. In addition, flicker measurement values and arrangement patterns of the second heaters 220 and 230 are shown.

  As shown in FIG. 13, when the lighting control of the first heater 220 is performed by the array pattern 7 and the lighting control of the second heater 230 is performed by the array pattern 8, the number of arrays of the array pattern 7 is “7”. Since the number of arrays of pattern 8 is “9”, the least common multiple is “63”. Therefore, when combined lighting control by the first and second heaters 220 and 230 is performed, the lighting control is performed with a common multiple of “63”. When the arrangement pattern 7 or 8 is changed to another arrangement pattern having a different duty ratio, the arrangement pattern is switched to a different arrangement pattern at the timing when the arrangement of the common multiple of “63” is completed.

  Further, the arrangement of the second heater 230 is changed to have the same duty ratio so that the off section of the arrangement pattern 8 of the second heater 230 does not coincide with the off section of the arrangement pattern 7 of the first heater 220. Further, the arrangement pattern 8 of the second heater 230 is set to duty so that 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 7 of the first heater 220. Change the ratio to be the same. 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. 14 shows the first and second cases 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%. 2 shows flicker measurement values and arrangement patterns of the two heaters 220 and 230.

  As shown in FIG. 14, when the lighting of the first heater 220 is controlled by the array pattern 8 and the lighting of the second heater 230 is controlled by the array pattern 9, the number of arrays of the array pattern 8 is “9”. Since the number of arrangements of the pattern 9 is “5”, the least common multiple is “45”. Therefore, when combined lighting control is performed by the first and second heaters 220 and 230, the lighting control is performed with a common multiple of “45”. When the arrangement pattern 8 or 9 is changed to an arrangement pattern having a different duty ratio, the arrangement pattern is switched to a different arrangement pattern at the timing when the arrangement of the common multiple of “45” is completed.

  Also, the duty ratio of the array pattern 8 of the first heater 220 is the same so that the ON section of the array pattern 8 of the first heater 220 is not in the same position as the ON section of the array pattern 9 of the second heater 230. Change as Further, the duty ratio of the array pattern 8 of the first heater 220 is the same so that the off section of the array pattern 8 of the first heater 220 does not coincide with the off section of the array pattern 9 of the second heater 230. Change as 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. 15 shows the first and second cases when 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%. 2 shows flicker measurement values and arrangement patterns of the two heaters 220 and 230.

  As shown in FIG. 15, when the lighting of the first heater 220 is controlled by the array pattern 8 and the lighting of the second heater 230 is controlled by the array pattern 11, the number of arrays of the array pattern 8 is “9”. Since the number of arrangements of the pattern 11 is “5”, the least common multiple is “45”. Therefore, when combined lighting control is performed by the first and second heaters 220 and 230, the lighting control is performed with a common multiple of “45”. When the arrangement pattern 8 or 11 is changed to an arrangement pattern having a different duty ratio, the arrangement pattern is switched to a different arrangement pattern at the timing when the arrangement of the common multiple of “45” is completed.

  Also, the duty ratio of the array pattern 8 of the first heater 220 is the same so that the ON section of the array pattern 8 of the first heater 220 does not coincide with the ON section of the array pattern 11 of the second heater 230. Change as Further, the arrangement of the arrangement pattern 8 of the first heater 220 is set to duty so that the off section of the arrangement pattern 8 of the first heater 220 is not continuously located at the same position as the off section of the arrangement pattern 11 of the second heater 230. Change the ratio to be the same. 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. 16 shows flicker measurement values and arrangement patterns of the first and second heaters 220 and 230 when both the first and second heaters 220 and 230 are turned on by the arrangement pattern 9 having a duty ratio of 40%. Show.

  As shown in FIG. 16, when both the first and second heaters 220 and 230 are controlled to be lit by the array patterns 9 and 9, the number of the array patterns 9 and 9 is “5”, and the least common multiple is “5”. Therefore, when combined lighting control by the first and second heaters 220 and 230 is performed, the lighting control is performed with a common multiple of “5”. When the arrangement pattern 9 or 9 is changed to an arrangement pattern having a different duty ratio, the arrangement pattern is switched to a different arrangement pattern at the timing when the arrangement of the common multiple of “5” is completed.

  Also, the duty ratio of the array pattern 9 of the first heater 220 is the same so that the ON section of the array pattern 9 of the first heater 220 does not coincide with the ON section of the array pattern 9 of the second heater 230. Change as Further, the arrangement of the arrangement pattern 9 of the first heater 220 is set to duty so that 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. Change the ratio to be the same. 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]
FIG. 17 shows an example of the configuration of the table TB used during lighting control of the first and second heaters 220 and 230. In FIG. 17, only the duty ratio is shown, but an array pattern corresponding to the duty ratio is actually stored. FIG. 17 shows flicker measurement values when the first heater 220 is turned on by the array patterns 3 to 6 and the second heater 230 is turned on by the array patterns 6 to 11. The array patterns and flicker measurement values of other combinations shown are also stored in the table TB. In the table TB, combinations of array patterns in which the flicker specified values in the first and second heaters 220 and 230 are cleared and flicker measurement values of the array patterns are stored in association with each other. The table TB is created, for example, before shipment of the image forming apparatus 100A, and is stored in the storage unit 280 in advance.

[Operation example of image forming apparatus]
Next, an operation example of the image forming apparatus 100A during temperature control of the first and second heaters 220 and 230 according to the first embodiment will be described. FIG. 18 is a flowchart illustrating an example of the operation of the image forming apparatus 100A during the temperature control of the first and second heaters 220 and 230.

  As shown in FIG. 18, in step S100, the control unit 250 starts lighting control of the first and second heaters 220 and 230 based on an arrangement pattern corresponding to a predetermined duty ratio in the current control cycle. The duty ratio is calculated based on the temperature information of the first and second heaters 220 and 230 acquired in the control cycle prior to the current control cycle. For example, when the controller 250 controls lighting of the first and second heaters 220 and 230 with the arrangement patterns 2 and 2 shown in FIG. 3 in the current control cycle, the arrangement number of the arrangement patterns 2 and 2 is “7”. Therefore, the lighting control is performed in the control cycle based on the common multiple of “7”.

  In step S <b> 110, the temperature sensor 222 detects the temperature of the first heater 220, and the temperature sensor 232 detects the temperature of the second heater 230. The control unit 250 acquires the temperature information of the first and second heaters 220 and 230 detected by the temperature sensors 222 and 232, and stores the temperature information in the current control cycle in the storage unit 280.

  In step S120, the control unit 250 determines the duty ratios of the first and second heaters 220 and 230 in the next control cycle based on the acquired temperature information of the first and second heaters 220 and 230. For example, the control unit 250 calculates and determines the duty ratios of the first and second heaters 220 and 230 based on the difference value between each acquired temperature information and each preset target temperature. The duty ratio can also be calculated by PI control.

  In step S130, the control unit 250 determines an arrangement pattern corresponding to the determined duty ratio of the first and second heaters 220 and 230. For example, when the flicker priority mode is set as the lighting mode, the control unit 250 selects and determines from the table TB the combination of the arrangement patterns of the first and second heaters 220 and 230 having the smallest flicker measurement value. To do. In addition, when the temperature ripple priority mode is set, the control unit 250 can calculate lighting more stably by selecting a duty ratio that is close to the calculated duty ratio, and can improve temperature ripple. A duty ratio indicating a value closest to the duty ratio is selected from the table TB and determined.

  In step S140, the control unit 250 determines whether or not the arrangement of common multiples of the arrangement patterns of the first and second heaters 220 and 230 in the current control cycle has been completed. If the controller 250 determines that the arrangement of the common multiples of the arrangement pattern of the first and second heaters 220 and 230 in the current control cycle has been completed, the process proceeds to step S150. On the other hand, when the control unit 250 determines that the arrangement of the common multiples of the arrangement pattern of the first and second heaters 220 and 230 in the current control cycle is not completed, the arrangement of the common multiples of each arrangement pattern is completed. The lighting control of the array pattern of the current control cycle is executed until

  In step S150, when the arrangement of the common multiples of the arrangement pattern of the first and second heaters 220 and 230 in the current control cycle is completed, the control unit 250 changes the arrangement pattern to the determined duty ratio and changes it in the next control cycle. The lighting control of the first and second heaters 220 and 230 is started according to the arrangement pattern. For example, the lighting control of the first and second heaters 220 and 230 is performed with the arrangement patterns 2 and 2 shown in FIG. 3 in the current control cycle, and the first and second heaters 220 and 230 in FIG. 3 in the next control cycle. When the lighting control is performed with the array patterns 2 and 8 shown, the control unit 250 sets the duty ratio (array pattern) to the array pattern 2 of the next control period when the array of common multiples of “7” in the current control period is completed. Change to 8. In this example, such a lighting control process is repeatedly executed.

  Conventionally, if the array pattern is switched other than the common multiple of the array pattern, the array pattern itself is shifted (changed) in combination with the array pattern of the next control cycle, and an array pattern advantageous to flicker is used. However, sometimes the flicker regulation value could not be cleared. On the other hand, according to the first embodiment, the arrangement pattern is switched when the arrangement of common multiples of the arrangement numbers of the arrangement patterns of the first and second heaters 220 and 230 is completed. Switching control that observes the arrangement can be performed. As a result, the flicker regulation value can be reliably cleared.

  Further, according to the first embodiment, it is possible to prevent deterioration of temperature ripple. 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>
The second embodiment is different from the first embodiment in that the lighting control is performed by adopting the common multiple of the arrangement pattern of the first and second heaters 220 and 230 that is closest to the reference control cycle. It is different. Since the configuration and operation of the other image forming apparatus 100B are the same as those in the first embodiment, common constituent elements are denoted by the same reference numerals, and detailed description thereof is omitted.

  The control period is a reference period when the duty ratio is switched, and the temperature of the first and second heaters 220 and 230 is reflected on the fixing after the duty ratio of the first and second heaters 220 and 230 is changed. It is set in consideration of the delay until it is done. For example, if the time during which the temperature of the first and second heaters 220 and 230 is reflected in the fixing by changing the duty ratio is 1000 ms, the control cycle is set to 1000 ms, and every 1000 ms according to a command from the control unit 250. The duty ratio (arrangement pattern) of the first and second heaters 220 and 230 is changed.

  However, if the duty ratio is changed by an arrangement other than the common multiple of the arrangement pattern of the first and second heaters 220 and 230, there is a possibility that the flicker may be adversely affected. Therefore, in the second embodiment, the control cycle is changed to be close to the original reference control cycle in accordance with the result of switching the common multiple of the arrangement number of the arrangement patterns of the first and second heaters 220 and 230.

[Operation example of image forming apparatus]
Next, an operation example of the image forming apparatus 100B during temperature control of the first and second heaters 220 and 230 according to the second embodiment will be described. FIG. 19 is a flowchart illustrating an example of the operation of the image forming apparatus 100 </ b> B during temperature control of the first and second heaters 220 and 230.

  As shown in FIG. 19, in step S200, the control unit 250 starts lighting control of the first and second heaters 220 and 230 based on an arrangement pattern corresponding to a predetermined duty ratio in the current control cycle.

  In step S210, the temperature sensor 222 detects the temperature of the first heater 220, and the temperature sensor 232 detects the temperature of the second heater 230. The control unit 250 acquires temperature information of the first and second heaters 220 and 230 detected by the temperature sensors 222 and 232.

  In step S220, the control unit 250 determines the duty ratios of the first and second heaters 220 and 230 in the next control cycle based on the acquired temperature information of the first and second heaters 220 and 230.

  In step S230, the control unit 250 determines an arrangement pattern corresponding to the determined duty ratio of the first and second heaters 220 and 230.

  In step S240, the control unit 250 determines a common multiple that is close to a preset reference control cycle among the common multiples of the determined arrangement patterns of the first and second heaters 220 and 230 as a control cycle. In this example, the time until the temperature is reflected by changing the duty ratios of the first and second heaters 220 and 230 is 1000 ms, and the reference control period for changing the duty ratio is 1000 ms. Since the frequency of the AC power supply 210 is 50 Hz, one array of each array pattern is 10 ms.

  When the determined arrangement pattern of the first and second heaters 220 and 230 is the arrangement pattern 2 with the duty ratio “85.71%”, the arrangement pattern of the first and second heaters 220 and 230 in the next control cycle Since the number of arrays in one control unit of 2 and 2 is “7”, the least common multiple of the array patterns 2 and 2 is “7”.

  The control unit 250 multiplies “10” by “7”, which is the least common multiple of the array patterns 2 and 2, to obtain “70 ms”, and obtains “70 ms” as the common multiple of the array patterns 2 and 2 close to “1000 ms” of the reference control period. “980 ms” and “1050 ms” are calculated. The control unit 250 determines “980 ms”, which is a common multiple close to the set reference control cycle, among the two calculated common multiples as the next control cycle. Note that the control cycle can also be calculated by calculation by the process of step S340 described in FIG. 21 of the third embodiment described later.

  In step S250, the control unit 250 determines whether or not the arrangement of common multiples of the arrangement patterns of the first and second heaters 220 and 230 in the current control cycle has been completed. When the control unit 250 determines that the arrangement of the common multiples of the arrangement pattern of the first and second heaters 220 and 230 in the current control cycle has been completed, the control unit 250 proceeds to step S260, and the first and second heaters 220 and 230 are performed. If it is determined that the arrangement of the common multiples of the arrangement pattern is not completed, the lighting control of the arrangement pattern of the current control cycle is executed until the arrangement of the common multiples of the arrangement patterns is completed.

  In step S260, the control unit 250 changes to the determined duty ratio array pattern and control cycle when the array of common multiples of the array pattern of the first and second heaters 220 and 230 in the current control cycle is completed. The lighting control of the first and second heaters 220 and 230 is started with the changed arrangement pattern and control cycle. For example, as described above, when the determined arrangement pattern of the first and second heaters 220 and 230 is the arrangement pattern 2 with the duty ratio “85.71%”, the control unit 250 sets the control cycle to “1000 ms. To “980 ms”.

  As described above, in the second embodiment, a common multiple of the common pattern of each arrangement pattern of the first and second heaters 220 and 230 is selected and determined as the next control cycle. . Thereby, since the reflection time of temperature information can be made close to the original basic control cycle, the temperature of the first and second heaters 220 and 230 can be adjusted to a temperature close to the target temperature more accurately and with high accuracy. it can. Further, since the duty ratio is changed to the next duty ratio when the arrangement of the common multiples of the arrangement pattern is completed, switching in compliance with the arrangement pattern can be performed, and the lighting control can be executed without setting the flicker value to NG. .

<Third Embodiment>
In the third embodiment, the lighting control is performed by adopting a common multiple of the arrangement pattern of the first and second heaters 220 and 230 that is longer than the reference control period to perform the lighting control. This is different from the embodiment. Since the configuration and operation of the other image forming apparatus 100C are the same as those in the first embodiment and the like, common constituent elements are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 20 is a diagram for explaining problems in the conventional temperature control of the fixing device. When the first and second heaters 220 and 230 are controlled to be lighted by the array patterns 2 and 2 shown in FIG. 3 when the reference control period is, for example, 1000 ms, the control period of the common multiples of these array patterns 2 and 2 The common multiple close to is “980 ms” if it is shorter than the reference control period, and “1050 ms” if it is longer than the reference control period. Ideally, it is desirable to change the arrangement pattern (duty) at a time closer to the reference control period set as the time at which the temperature information is reflected.

  However, when the duty is changed by “980 ms” as the control cycle, since the reference control cycle “1000 ms” has not been reached, the change processing (reflection) is performed with the old temperature information one control cycle before the duty change. Therefore, there is a problem that the real-time property is lacking. On the other hand, when the control cycle is “1050 ms”, it exceeds the reference control cycle “1000 ms”, so that the latest temperature information can be reflected in fixing.

  Therefore, in the third embodiment, the common multiple of the arrangement patterns of the first and second heaters 220 and 230 is longer than the original reference control cycle and the closest multiple to the reference control cycle is set as the next control cycle. Determine as.

[Operation example of image forming apparatus]
Next, an operation example of the image forming apparatus 100C during temperature control of the first and second heaters 220 and 230 according to the third embodiment will be described. FIG. 21 is a flowchart illustrating an example of the operation of the image forming apparatus 100 </ b> C during temperature control of the first and second heaters 220 and 230. Below, the case where the temperature control of the 1st and 2nd heaters 220 and 230 is performed by the single control part 250 is demonstrated.

  As shown in FIG. 21, in step S300, the control unit 250 starts lighting control of the first and second heaters 220 and 230 based on an arrangement pattern corresponding to a predetermined duty ratio in the current control cycle.

  In step S <b> 310, the temperature sensor 222 detects the temperature of the first heater 220, and the temperature sensor 232 detects the temperature of the second heater 230. The control unit 250 acquires temperature information of the first and second heaters 220 and 230 detected by the temperature sensors 222 and 232.

  In step S320, the control unit 250 determines the duty ratios of the first and second heaters 220 and 230 in the next control cycle based on the acquired temperature information of the first and second heaters 220 and 230.

  In step S330, the control unit 250 determines an arrangement pattern corresponding to the determined duty ratios of the first and second heaters 220 and 230.

  In step S340, after determining the arrangement pattern, the control unit 250 performs an operation according to the following equation (1).

Reference control cycle / (Least common multiple of array pattern of duty ratio of next control cycle × 10)
... (1)
In this example, the time until the temperature is reflected by changing the duty ratios of the first and second heaters 220 and 230 is 1000 ms, and the reference control period for changing the duty ratio is 1000 ms. Since the frequency of the AC power supply 210 is 50 Hz, one array of each array pattern is 10 ms.

  When the determined arrangement pattern is the arrangement pattern 2 with the duty ratio “85.71%”, the number of arrangements of one control unit of the arrangement patterns 2 and 2 in the first and second heaters 220 and 230 in the next control cycle is Since each is “7”, the least common multiple of the array patterns 2 and 2 is “7”. When the reference control period “1000 ms” is divided by the common multiple “70 ms”, the calculation result according to the above equation (1) becomes “14.285.

  The control unit 250 rounds down the decimal point of the calculation result “14.2”, adds 1 to the first digit of the rounded calculation result to obtain “15”, and adds “70 ms to“ 15 ”of the addition result. ”To obtain“ 1050 ms ”. The control unit 250 determines the obtained “1050 ms” as the next control cycle.

  In step S350, control unit 250 determines whether or not the arrangement of common multiples of the arrangement pattern of the current control period has been completed. When it is determined that the arrangement of the common multiples of the array pattern of the current control cycle has been completed, the control unit 250 proceeds to step S360, and when it is determined that the arrangement of the common multiples of the array pattern of the current control cycle has not ended. The lighting control of the array pattern is executed in the current control period until the array of common multiples is completed.

  In step S360, when the arrangement of the common multiples of the arrangement pattern of the current control cycle is completed, the control unit 250 changes the arrangement pattern and control cycle of the determined duty ratio to the first by the arrangement pattern and control cycle changed in the next control cycle. And lighting control of the 2nd heaters 220 and 230 is started.

  As described above, in the third embodiment, the common multiple of each arrangement pattern of the first and second heaters 220 and 230 is longer than the original reference control cycle and is the closest common reference cycle. Is determined as the next control cycle. Thereby, the temperature information can be reflected in the fixing process in real time. Further, when the temperature control, duty ratio switching, image formation processing, and the like of the fixing device 200 are performed by the same (single) control unit 250, the control cycle can be prevented from being frequently changed. And control load can be reduced. Further, cost and arrangement space can be reduced.

<Fourth embodiment>
The fourth embodiment is different from the first to third embodiments in that a sub-control unit 252 that specializes lighting control of the first and second heaters 220 and 230 is provided. Since the configuration and operation of the other image forming apparatus 100D are the same as those in the first embodiment and the like, common constituent elements are denoted by the same reference numerals and detailed description thereof is omitted.

[Configuration example of image forming apparatus]
FIG. 22 shows an example of a block configuration of an image forming apparatus 100D according to the fourth embodiment. As illustrated in FIG. 22, the image forming apparatus 100 </ b> D includes an AC power supply 210, a fixing device 200, a control unit (first control unit) 250, a sub control unit (second control unit) 252, and a storage unit. 280. The control unit 250 performs processing such as image formation processing, receives temperature information of the first heaters 220 and 230 measured by the temperature sensors 222 and 232, and supplies the temperature information to the sub-control unit 252.

  The sub-control unit 252 has a CPU specialized for lighting control of the first and second heaters 220 and 230, and is based on temperature information of the first and second heaters 220 and 230 supplied from the control unit 250. Thus, the duty ratio and the array pattern are determined, the control cycle is determined based on the determined array pattern, and the array pattern is changed (switched) in units of the determined control cycle.

[Operation example of image forming apparatus]
Next, an operation example of the image forming apparatus 100D during temperature control of the first and second heaters 220 and 230 according to the fourth embodiment will be described. FIG. 23 is a flowchart illustrating an example of the operation of the image forming apparatus 100D during temperature control of the first and second heaters 220 and 230. FIG. 24 is an explanatory diagram in the case where the common multiple of the arrangement patterns of the first and second heaters 220 and 230 that is closest to the original reference control cycle is determined as the next control cycle.

  As shown in FIG. 23, in step S400, the sub-control unit 252 starts lighting control of the first and second heaters 220 and 230 based on an array pattern corresponding to a predetermined duty ratio in the current control cycle.

  In step S410, the temperature sensor 222 detects the temperature of the first heater 220, and the temperature sensor 232 detects the temperature of the second heater 230. The sub control unit 252 acquires temperature information of the first and second heaters 220 and 230 detected by the temperature sensors 222 and 232 from the control unit 250.

  In step S420, the sub-control unit 252 determines the duty ratio of the first and second heaters 220 and 230 in the next control cycle based on the acquired temperature information of the first and second heaters 220 and 230.

  In step S430, the sub-control unit 252 determines an arrangement pattern corresponding to the determined duty ratio of the first and second heaters 220 and 230.

  In step S440, the sub-control unit 252 performs calculation according to the above equation (1). Hereinafter, a first case in which the determined arrangement pattern of the first and second heaters 220 and 230 is the arrangement pattern 2 having a duty ratio of “85.71%”, and the determined arrangement of the first heater 220 will be described. A case where the pattern is the arrangement pattern 3 with the duty ratio “81.8%” and the arrangement pattern of the second heater 230 is the arrangement pattern 4 with the duty ratio “80%” will be described.

  In the case of the first case, the number of arrangements of one control unit of the arrangement patterns 2 and 2 in the first and second heaters 220 and 230 in the next control cycle is “7”, respectively. The common multiple is “7”. When the reference control period “1000 ms” is divided by the common multiple “70 ms”, the calculation result according to the above equation (1) becomes “14.285.

  In the case of the second case, the number of arrangements of one control unit of the arrangement pattern 3 in the first and second heaters 220 and 230 in the next control cycle is “11” and the arrangement number of one control unit of the arrangement pattern 4 is Since it is “5”, the least common multiple of the array patterns 3 and 4 is “55”. When the reference control period “1000 ms” is divided by the common multiple “550 ms”, the calculation result by the above equation (1) becomes “1.818.

  In step S450, the sub-control unit 252 determines whether or not the first digit after the decimal point of the calculation result according to the equation (1) is 4 or less. The sub-control unit 252 proceeds to step S460 when the first decimal place of the calculation result according to the above formula (1) is 4 or less, and proceeds to step S470 when the first decimal place of the calculation result exceeds 4. . For example, in the first case, the calculation result according to the above equation (1) is “14.285...”, And the first digit after the decimal point of the calculation result is 4 or less, so the process proceeds to step S460. In the case of the second case, the calculation result according to the above equation (1) is “1.818...”, And the first digit after the decimal point of the calculation result exceeds 4, so the process proceeds to step S470.

  In step S460, when the first digit after the decimal point of the operation result is 4 or less, the sub-control unit 252 rounds down the operation result to the next decimal point, and multiplies the operation result by the least common multiple × 10 to obtain the next control cycle. To decide. For example, in the first case, the calculation result “14.285...” Is rounded down to obtain “14”. Subsequently, the sub-control unit 252 calculates “980 ms” by multiplying the calculated “14” by the least common multiple “7” × 10, and as shown in FIG. 24, “980 ms” obtained by the calculation is calculated. Determined as the next control cycle.

  On the other hand, if the first decimal place of the operation result exceeds 4 in step S470, the sub control unit 252 rounds down the operation result and adds 1 to the first digit of the operation result. Multiply × 10 to determine the next control period. For example, in the second case, the calculation result “1.818...” Is rounded down to obtain “1”, and 1 is added to “1” to obtain “2”. Subsequently, the sub-control unit 252 calculates “1100 ms” by multiplying “2” by the least common multiple “55” × 10, and determines “1100 ms” obtained by the calculation as the next control period.

  In step S480, the sub-control unit 252 determines whether or not the arrangement of common multiples of the arrangement pattern of the current control period has been completed. If the sub-control unit 252 determines that the arrangement of the common multiples of the array pattern of the current control cycle is complete, the sub-control unit 252 proceeds to step S490, and determines that the array of the common multiples of the array pattern of the current control period is not complete. Performs the lighting control of the array pattern in the current control period until the array of common multiples is completed.

  In step S490, the sub-control unit 252 changes the arrangement pattern and control cycle to the determined duty ratio when the arrangement of the common multiple of the arrangement pattern of the current control cycle is completed, and changes the first arrangement pattern and control cycle in the next control cycle. The lighting control of the first and second heaters 220 and 230 is started.

  As described above, according to the fourth embodiment, the dedicated sub-control unit 252 for switching the duty ratio of the first and second heaters 220 and 230 is provided. The control load can be reduced. As a result, the control unit 250 can preferentially execute processes other than the lighting control of the first and second heaters 220 and 230, so that the control can be prevented from becoming complicated and image formation can be performed efficiently. Processing can be performed. Further, since the sub-control unit 252 can also specialize in switching the duty ratio and the like, it is possible to perform lighting control more efficiently and quickly.

  Further, since the common multiple of the arrangement patterns of the first and second heaters 220 and 230 that is closest to the original reference control cycle is determined as the next control cycle, the temperature is close to the target temperature more accurately and accurately. The temperature of the first and second heaters 220 and 230 can be adjusted. Further, since the duty ratio is changed to the next duty ratio when the arrangement of the common multiples of the arrangement pattern is completed, switching in compliance with the arrangement pattern can be performed, and the lighting control can be executed without setting the flicker value to NG. .

  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-described embodiment, the example in which the fixing device 200 is configured by the two first and second heaters 220 and 230 has been described. However, the present invention is applicable even when the fixing device 200 is configured by three or more heaters. Can be applied. In the above embodiment, the image forming apparatuses 100A, 100B, 100C, and 100D that form color images have been described. However, the present invention can also be applied to image forming apparatuses that form monochrome images.

DESCRIPTION OF SYMBOLS 10 Image forming part 100A, 100B, 100C, 100D Image forming apparatus 200 Fixing apparatus 210 AC power supply 220 1st heater 230 2nd heater 250 Control part (1st control part)
252 Sub-control unit (second control unit)
260,270 switching part

Claims (5)

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 an 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 configured by different array numbers by ON / OFF in units of half-wave periods of the AC power supply,
The controller is
When controlling the lighting of each of the plurality of heaters according to the array pattern of a predetermined duty ratio, the array pattern is switched when the array of common multiples of the array number of the array patterns of the plurality of heaters is finished ,
The fixing device, wherein a common multiple of the array pattern that is close to a reference control cycle that is a reference among the common multiples of the array patterns of the plurality of heaters and that is longer than the reference control cycle is used as a control cycle . 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 an 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 configured by different array numbers by ON / OFF in units of half-wave periods of the AC power supply,
The control unit includes a first control unit and a second control unit that performs control different from the control by the first control unit,
The second controller is
When controlling the lighting of each of the plurality of heaters according to the array pattern of a predetermined duty ratio, the array pattern is switched when the array of common multiples of the array number of the array patterns of the plurality of heaters is finished ,
Of the common multiples of the array pattern of the plurality of heaters, a control period is a common multiple of the array pattern that is close to a reference control cycle that is a reference and shorter than the reference control cycle, or of the array pattern of the plurality of heaters A fixing device that determines whether a common multiple of the array pattern that is close to the reference control cycle and longer than the reference control cycle among the common multiples is set as a control cycle . Wherein the control unit, a fixing device according to claim 1 or 2, characterized in that changing the control period in accordance with the sequence number of a common multiple of the arrangement pattern of the plurality of heaters. An image forming unit for forming an image on paper;
A fixing device for fixing an image formed by the image forming unit to a sheet;
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, and
The controller is
The lighting control of the plurality of heaters is performed by switching the switching unit according to an array pattern composed of different array numbers by ON / OFF with the half wave period of the AC power supply as a unit, and each of the plurality of heaters is predetermined. When the lighting control is performed by the arrangement pattern of the duty ratio of the plurality of heaters, the arrangement pattern is switched when the arrangement of the common multiple of the arrangement number of the arrangement pattern of the plurality of heaters is completed ,
An image forming apparatus comprising: a common multiple of the array pattern that is close to a reference control cycle that is a reference among the common multiples of the array patterns of the plurality of heaters and that is longer than the reference control cycle . An image forming unit for forming an image on paper;
A fixing device for fixing an image formed by the image forming unit to a sheet;
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, and
The control unit includes a first control unit and a second control unit that performs control different from the control by the first control unit,
The second controller is
The lighting control of the plurality of heaters is performed by switching the switching unit according to an array pattern composed of different array numbers by ON / OFF with the half wave period of the AC power supply as a unit, and each of the plurality of heaters is predetermined. When the lighting control is performed by the arrangement pattern of the duty ratio of the plurality of heaters, the arrangement pattern is switched when the arrangement of the common multiple of the arrangement number of the arrangement pattern of the plurality of heaters is completed ,
Of the common multiples of the array pattern of the plurality of heaters, a control period is a common multiple of the array pattern that is close to a reference control cycle that is a reference and shorter than the reference control cycle, or of the array pattern of the plurality of heaters An image forming apparatus that determines whether a common multiple of the array pattern that is close to the reference control cycle and longer than the reference control cycle among the common multiples is set as a control cycle .