JP2018173528A - Image forming apparatus, method for controlling heater, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology that enables determination and control according to wiring impedance.SOLUTION: An image forming apparatus receives a signal from a sensor while energizing a heater and detects a predetermined amount of detection, measures the length of a specific time that is the time from the timing at which the amount of detection becomes zero until the timing at which the amount of detection reaches a peak, when the length of the specific time is within a predetermined range, executes first control of controlling energization to the heater in a first energization pattern, and when the length of the specific time is outside the predetermined range, executes second control of controlling energization to the heater in a second energization pattern for reducing the occurrence of a flicker phenomenon or reducing the visual sensitivity to the flicker phenomenon compared with the first control.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image forming apparatus including a heater, a heater control method, and a program.

  2. Description of the Related Art Conventionally, an image forming apparatus that forms an image by an electrophotographic method is known to include a fixing device having a heater and a heating roller heated by the heater. Also known is a technique for controlling energization to the heater so that the surface temperature of the heating roller becomes a desired temperature. A configuration of a conventional fixing device and heater energization control is disclosed in, for example, Patent Document 1.

JP 2008-090110 A

  When the wiring distance from the switchboard to the image forming device is long, when the number of branches from one switchboard is large, or when the equipment is aging, the environment where the wiring impedance from the external power supply to the image forming device is large There is. When the wiring impedance is large, when power supply to the image forming apparatus is started, there is a possibility that a so-called flicker phenomenon (flickering phenomenon) may occur in lighting equipment connected to the same external power source.

  The present invention has been made to solve the above-described problems of the prior art. That is, the problem is to provide a technique that can make judgment and control according to the wiring impedance.

In order to solve the above problems, the image forming apparatus of the present invention has the following configuration.
A heater that receives supply of power from an external power source, a sensor that outputs a different signal according to the amount of current or voltage supplied to the heater from the external power source, and a controller, the controller including the heater In a state in which the detection amount is received, a predetermined detection amount is detected by receiving a signal from the sensor, a timing at which the detection amount becomes zero is detected, a timing at which the detection amount reaches a peak is detected, and the detection amount is Measuring the length of a specific time, which is the time from the timing when it becomes zero to the timing when the detected amount reaches a peak, and determining whether the length of the specific time is within a predetermined range or out of a predetermined range; It is characterized by.

  If the wiring impedance is high, when the energization of the image forming apparatus is started, that is, when the energization of the heater is started, the timing at which the detection amount reaches a peak is biased. Therefore, the image forming apparatus disclosed in the present specification detects the length of time (specific time) from the timing when the detection amount becomes zero to the timing when the detection amount reaches a peak, and the specific time falls within a predetermined range. Otherwise, since there is a high possibility that the wiring impedance is high, an energization pattern that suppresses the occurrence of the flicker phenomenon or reduces the visibility to the flicker phenomenon makes it less susceptible to the flicker phenomenon.

  A heater control method and program for realizing the functions of the apparatus are also novel and useful.

  According to the present invention, a technique capable of determining and controlling according to the wiring impedance is realized.

1 is a cross-sectional view illustrating a schematic configuration of a printer according to a first embodiment. FIG. 2 is a block diagram illustrating an electrical configuration of a printer. It is a circuit diagram which shows the electric constitution of a power supply part. It is a flowchart which shows the control procedure concerning heater control. It is a flowchart which shows the control procedure concerning a power supply determination process. It is a flowchart which shows the control procedure regarding the determination processing regarding a power supply impedance. It is a figure which shows the relationship between the actual measurement current waveform measured with the current sensor, and its differentiation result. (A) It is a figure which simplifies and shows the current waveform at the time of supplying electric power to the fixing heater by wave number control. (B) It is a figure which simplifies and shows the current waveform at the time of supplying electric power to the fixing heater by wave number control after phase control. 6 is a circuit diagram showing an electrical configuration of a power supply unit according to Embodiment 2. FIG. It is a flowchart which shows the control procedure of a zero cross detection process. It is a figure which shows the relationship between the change of the voltage value of a commercial power source, and the change of the current value measured with a current sensor. It is a figure which shows the relationship between the change of the electric current value measured with a current sensor, and zero cross detection. FIG. 6 is a circuit diagram showing an electrical configuration of a power supply unit according to a third embodiment.

(Embodiment 1)
Hereinafter, a printer as an example embodying an image forming apparatus according to the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are drawn with simplified or modified exaggeration as appropriate, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily the same as those in the examples. In the present embodiment, the present invention is applied to a laser printer capable of forming a color image, but it goes without saying that the present invention may be applied to a laser printer capable of forming a monochrome image. Absent.

FIG. 1 is a cross-sectional view illustrating a schematic configuration of the printer according to the first embodiment.
In the figure, a printer 100 is a so-called tandem color laser printer. The printer 100 includes process units 10Y, 10M, 10C, and 10K for each color of yellow (Y), magenta (M), cyan (C), and black (K). The process unit 10 </ b> K includes a photoreceptor 2, a charger 3, and a developing device 4. The other color process units 10Y, 10M, and 10C have the same configuration. In addition, the printer 100 includes a main motor for driving the photosensitive member 2, the developing device 4, and the like. Further, the printer 100 has an exposure device 6 common to each color above the process units 10Y, 10M, 10C, and 10K for each color.

  The exposure device 6 includes a polygon motor for rotationally driving the polygon mirror, a motor driving unit for controlling the polygon motor, and the like.

  Further, the printer 100 includes a transfer belt 7, a thermal fixing device 8, a paper feed tray 91, and a paper discharge tray 92. Further, the heat fixing device 8 includes an upper heating roller 81, a fixing heater 82 disposed in the heating roller 81, a temperature sensor 83 made of, for example, a thermistor element disposed near the heating roller 81, and A pressure roller 84 disposed below the heating roller 81 and a drive motor for driving the heating roller 81 are provided. The heating roller 81 is heated to a predetermined temperature by the fixing heater 82, and the surface temperature of the heating roller 81 is detected by the temperature sensor 83. The fixing heater 82 is an example of the heater of the present invention.

Next, the overall operation of the printer 100 will be briefly described.
The printer 100 is connected to a host device (not shown) such as a personal computer via a network, for example. Further, the printer 100 receives a plurality of print data from a host device and forms an image based on the print data, and a plurality of modes such as a sleep mode and a standby mode that are appropriately set according to the status of the printer 100 when no image is formed. In the following description, the print mode and the sleep mode will be mainly described. In the following description, the entire printing operation in the printing mode will be briefly described. In particular, image formation by the process unit 10K will be described.

  That is, in the printing operation in the printing mode, the printer 100 charges the photoreceptor 2 with the charger 3 and then exposes it with the exposure device 6. Thereby, an electrostatic latent image based on the image data is formed on the surface of the photoreceptor 2. Further, the printer 100 forms a toner image by developing the electrostatic latent image with the developing device 4.

  Further, the printer 100 pulls out the sheets stored in the paper feed tray 91 one by one and conveys them to the transfer belt 7. The transfer belt 7 includes a transfer roller 5 on the inner side of the contact position with the photosensitive member 2, and transfers the toner image on the photosensitive member 2 to the sheet when the sheet passes between the photosensitive member 2 and the transfer roller 5. To do. Further, the printer 100 heats the toner image placed on the sheet by the heating roller 81 of the heat fixing device 8 when the sheet passes between the heating roller 81 and the pressure roller 84 of the heat fixing device 8. To heat-fix the sheet. Thus, the sheet on which the image is formed is discharged to the paper discharge tray 92.

  When performing color printing, the printer 100 forms toner images of the respective colors in the process units 10Y, 10M, and 10C of other colors, and sequentially transfers them to a sheet. Thereby, the toner images of the respective colors are superimposed on the sheet. Then, a color image is formed by fixing the superimposed toner images on the sheet.

FIG. 2 is a block diagram showing the electrical configuration of the printer. Next, the electrical configuration of the printer 100 will be described with reference to FIG.
That is, the printer 100 includes a controller 30 including a CPU 31, a ROM 32, a RAM 33, and an NVRAM (nonvolatile RAM) 34. The printer 100 includes a motor 11 as an example of a DC 24V load, an operation panel 35, a network interface 36, a USB interface 37, and a heat fixing device 8, which are electrically connected to the controller 30. Yes. The motor 11 may be a main motor for driving the photosensitive member 2 and the developing unit 4, a polygon motor provided in the exposure unit 6, or a driving motor for driving the heating roller 81. It may be a combination thereof.

  Further, the printer 100 includes a power supply unit 40 that is electrically connected to the controller 30. In the printing mode, the power supply unit 40 supplies power to the controller 30, the motor 11, and the fixing heater 82 of the heat fixing unit 8. Connected so that it can be supplied.

  The ROM 32 stores various control programs for controlling the printer 100, various settings, initial values, and the like. The RAM 33 is used as a work area from which various control programs are read, or as a storage area for temporarily storing data. The CPU 31 controls each component of the printer 100 while storing the processing result in the RAM 33 or the NVRAM 34 according to the control program read from the ROM 32. The RAM 33 or the NVRAM 34 constitutes a storage unit.

  The CPU 31 is an example of a control unit. The controller 30 may be an example of a control unit. Note that the controller 30 in FIG. 2 is a general term that summarizes hardware used to control the printer 100 such as the CPU 31. Specifically, the controller 30 includes an ASIC (Application Specific Integrated Circuit) and the like. Therefore, the ASIC may be responsible for a part of the function of the controller 30, and a part of the function of the controller 30 is a logic circuit. May be responsible.

  The network interface 36 is hardware for communicating with a host device connected via a network. The USB interface 37 is hardware for communicating with a device connected based on the USB standard. The operation panel 35 is hardware that is responsible for displaying a notification to the user and receiving an instruction input by the user.

FIG. 3 is a diagram illustrating an electrical configuration of the power supply unit, and subsequently, an electrical configuration of the power supply unit 40 will be described with reference to FIG. 3.
In the figure, an AC power of 100 V, for example, is supplied from an external power source 411 to a first input terminal 41 constituting a power input unit of the power supply unit 40. The voltage of the external power supply 411 is not limited to 100V, and may be 200V, for example. The external power source 411 may be a commercial AC power source outside the printer 100 or a power source by a private generator.

  The input terminal of the noise filter 60 is connected to the first input terminal 41 via the first line L1 and the second line L2. The noise filter 60 removes noise from the subsequent stage of the noise filter 60.

  A rectifier circuit 42 composed of a diode bridge is connected to the output terminal of the noise filter 60. Therefore, the AC power supplied from the first input terminal 41 is full-wave rectified by the rectifier circuit 42.

  An AC / DC converter 43 is connected to the output terminal of the noise filter 60. The AC / DC converter 43 is connected between the rectifier circuit 42 formed of a diode bridge connected to the output terminal of the noise filter 60 and the output terminal of the rectifier circuit 42, and the smoothing capacitor 431 that smoothes the output current of the rectifier circuit 42. And a transformer 432 having a primary winding connected between the output terminals of the rectifier circuit 42 via a switching element 433, and a rectifying / smoothing circuit 44.

  Therefore, AC power supplied from the first input terminal 41 and output from the output terminal of the noise filter 60 is full-wave rectified by the rectifier circuit 42 and then smoothed by the smoothing capacitor 431. The smoothing capacitor 431 is an example of the capacitor of the present invention, and the AC / DC converter 43 is an example of the converter of the present invention. Further, the smoothing capacitor 431 may be composed of a plurality of capacitors connected in parallel.

  The rectifying / smoothing circuit 44 connected to the secondary winding of the transformer 432 includes a rectifying element 441 and a smoothing capacitor 442, and after rectifying the power output from the secondary winding of the transformer 432 by the rectifying element 441, The output is smoothed by the capacitor 442. For example, the DC 24V power output from the rectifying / smoothing circuit 44 is supplied to the DC 24V load represented by the motor 11 via the first output terminal 45.

  Further, the DC / DC converter 46 is connected to the first output terminal 45 via the second input terminal 52, and therefore, the DC 24V power output from the first output terminal 45 is the DC / DC converter. 46. The DC / DC converter 46 converts 24V power to 3.3V, and the power output from the DC / DC converter 46 is supplied to the controller 30 and the like.

  The power supply control IC 63 is for switching control of the switching element 433 of the AC / DC converter 43.

  One end side of the third line L3 is connected to the first branch point P1 provided on the first line L1, and the other end side of the third line L3 is fixed via the electromagnetic relay 49. The heater 82 is connected to one terminal.

  In addition, one end side of the fourth line L4 is connected to the second branch point P2 provided on the second line L2, and the other end side of the fourth line L4 is, for example, from a triac element. It is connected to the other terminal of the fixing heater 82 through the configured switching element 50. The switching element 50 is a switching element.

  The energization timing of the switching element 50 is controlled by a heater control signal from the controller 30 via the phototriac coupler 51. When the switching element 50 continuously receives an ON signal from the controller 30, the switching element 50 continues to be energized even at the next zero cross timing, and when the ON signal is not continuously received from the controller 30, the next external power supply A non-energized state is established at the zero cross timing of the voltage input from 411. The zero cross timing of the voltage input from the external power supply 411 is an example of the timing at which the voltage value of the external power supply 411 input from the first input terminal 41 passes zero volts.

  In the present embodiment, the electromagnetic relay 49 is disposed on the third line L3 and the switching element 50 is disposed on the fourth line L4. However, the electromagnetic relay 49 is disposed on the third line L3 or the fourth line L4. The electromagnetic relay 49 and the switching element 50 may be arranged in series.

  The contact of the electromagnetic relay 49 is controlled by a relay control signal from the controller 30.

  That is, in the printing mode, the contact of the electromagnetic relay 49 is controlled to be in an on state (energized state) by a relay control signal from the controller 30, and in the sleep mode, the contact is controlled to be in an off state (non-energized state). . Further, in the printing mode, when opening of the cover is detected via a switch (not shown) for detecting opening / closing of the cover of the printer 100, the energized state is changed to the non-energized state by the relay control signal from the controller 30. It is controlled and the safety of the device is ensured.

  The phototriac coupler 51 outputs a control signal to the switching element 50 based on the heater control signal from the controller 30. Accordingly, when the switching element 50 continuously receives the ON signal from the controller 30, the switching element 50 continues to be energized even at the next zero cross timing, and when the ON signal is not continuously received from the controller 30, The non-energized state is entered at the zero cross timing of the incoming external power supply 411.

  Therefore, in the printing mode, the first line L1, the first branch point P1, the third line L3, the electromagnetic relay 49, the switching element 50, the fourth line L4, the second branch point P2, and the second line. Electric power is supplied from the external power source 411 to the fixing heater 82 via L2, thereby heating the heating roller 81. Further, when the electromagnetic relay 49 or the switching element 50 is in a non-energized state, power is not supplied to the fixing heater 82.

  Between the first branch point P1 on the third line L3 and the electromagnetic relay 49, for example, a hall-type current sensor 55 using a hall element is arranged, and the current flowing through the third line L3 That is, the current value (current amount) supplied to the fixing heater 82 can be measured. Specifically, the current sensor 55 has a sampling period sufficiently finer than half of the AC period of the power supplied from the external power supply 411 and sufficiently finer than a time width in which one capacitor input current is generated. The value can be measured. The measured current value is output to the controller 30 as a current sensor signal via the second output terminal 47 and the third input terminal 48 in real time. The current sensor 55 is an example of the sensor of the present invention.

  As the current sensor, instead of the current sensor 55 capable of measuring the absolute value of the current value of the alternating current flowing on the first line L1, the relative value of the alternating current relative to the current value of zero is used. It is also possible to use a comparison type current sensor capable of measuring the current amount, and the current value and the relative current amount are examples of the detection amount of the present invention. Further, the current sensor 55 is connected between the first input terminal 41 and the first branch point P1 on the first line L1, and between the first input terminal 41 and the second branch point on the second line L2. It may be arranged between P2 and on the fourth line L4.

  However, the AC / DC converter 43 is more disposed when the current sensor 55 is disposed on the third line L3 or the fourth line L4 than when disposed on the first line L1 and the second line L2. Therefore, the current value (current amount) supplied to the fixing heater 82 can be measured (detected) more accurately.

  The first line L1 and the second line L2 correspond to the first line of the present invention, and the third line L3 and the fourth line L4 correspond to the second line of the present invention, respectively. Moreover, the 1st line and 2nd line of this invention point out the electric power path | route for transmitting electric power, and do not necessarily need to be connected mechanically continuously. That is, the power path only needs to have a function of transmitting power, and includes those that are intermittently connected via a switching member, a transformer, or the like.

  A zero cross detection circuit 56 is connected between the third line L3 between the electromagnetic relay 49 and the fixing heater 82 and the fourth line L4 between the second branch point P2 and the switching element 50. When the contact of the electromagnetic relay 49 is closed (energized), the zero cross point of the external power source 411 connected to the first input terminal 41 can be detected and the zero cross signal can be output to the controller 30 in real time. It is.

  FIG. 4 is a flowchart showing a control procedure related to heater control. Next, the control procedure will be described with reference to FIG. Note that the control shown in FIG. 4 is executed by the controller 30 at predetermined time intervals when the printer 100 is turned on or during the print mode period.

  That is, first, in step 1 (hereinafter referred to as S1), the controller 30 determines whether or not it is a print mode for printing the print data transmitted from the host device, and if it is not the print mode (S1: NO), in the next S7, the controller 30 controls the contact of the electromagnetic relay 49 to the ON state (non-energized state), and the present process ends.

  On the other hand, if it is the printing mode (S1: YES), in the next S2, the controller 30 controls the contact of the electromagnetic relay 49 from the on state (non-energized state) to the off state (energized state).

  Next, in S3, the controller 30 determines whether or not printing based on the print data transmitted from the host device is continuing. If printing is not continuing (S3: NO), this process ends. .

  On the other hand, if printing is continuing (S3: YES), in S4, the controller 30 compares the detected temperature value of the temperature sensor 83 with the reference temperature value. In S5, if the detected temperature value of the temperature sensor 83 exceeds the reference temperature value in the comparison in S4, it is determined that it is not necessary to supply power to the fixing heater 82 (S5: NO), and the process returns to S3. .

  If the detected temperature value of the temperature sensor 83 is lower than the reference temperature value in the comparison in S4, the controller 30 determines that power supply to the fixing heater 82 is necessary (S5: YES), and proceeds to S6. To do.

  Next, in S6, the controller 30 controls the energization state of the switching element 50 based on the heater control method set in S20 or S23 shown in FIG. 5 to be described later, thereby supplying power to the fixing heater 82. After that, the process returns to S3. Note that S6 is an example of an energization step and an energization process of the present invention.

  It should be noted that when the printer 100 is turned on, shifted from the sleep mode to the print mode, or when a new print job is started after one continuous print job is completed, FIG. Since the wave number control is set in step S13, power is supplied to the fixing heater 82 by the wave number control.

  FIG. 5 is a flowchart showing a control procedure related to the power source determination process. Next, the control procedure will be described with reference to FIG. The control shown in FIG. 5 is executed by the controller 30 at predetermined time intervals when the printer 100 is turned on or during the print mode period.

  That is, in S11, the controller 30 sets the value of the counter stored in the RAM 33 or NVRAM 34 to zero, and in the next S12, the controller 30 determines whether or not the contact of the electromagnetic relay 49 is in an on state (energized state). to decide. When the controller 30 determines that the contact of the electromagnetic relay 49 is not in the on state (energized state) (S12: NO), the determination in S12 is performed until the contact of the electromagnetic relay 49 is controlled to be in the on state (energized state). repeat.

  On the other hand, when the printer 100 is in the print mode and the above-described S2 shown in FIG. 4 is executed and the contact of the electromagnetic relay 49 is controlled to be in the ON state (energized state), in S12, the controller 30 It is determined that the contact of relay 49 is in an on state (energized state) (S12: YES), and in next S13, wave number control is set as heater control, and the process proceeds to next S14.

  Next, in S14, the controller 30 acquires the zero cross signal output from the zero cross detection circuit 56, calculates the AC half cycle (Tu) based on the zero cross signal, and proceeds to the next S15. Note that the AC half cycle (Tu) is a half wave of the power cycle of the external power source 411 as shown in FIG.

Next, in S15, the controller 30 determines whether or not the switching element 50 is energized. If it is determined that the switching element 50 is not energized (S15: NO), the controller 30 returns to S14.
On the other hand, when the controller 30 supplies power to the fixing heater 82 in order to heat the heating roller 81 in S6 shown in FIG. 4 described above, the controller 30 turns on the switching element 50 in S15. It is determined that the state has been controlled (S15: YES). In the next S16, the controller 30 determines whether or not the first wave in the heater control in the continuous series of print jobs out of the AC power supplied to the fixing heater 82. If it is determined that it is not the first wave (S16: NO), the process returns to S14.

On the other hand, when the controller 30 determines that it is the first wave in S16 (S16: YES), the determination process relating to the power source impedance is executed in the next S17 using the first half wave.
The determination process related to the power supply capacity is the determination process shown in FIG. 6. Next, the control procedure of the determination process related to the power supply impedance will be described with reference to FIG.

  That is, in S31, the controller 30 adds one counter value stored in the RAM 33 or the NVRAM 34. Next, in S <b> 32, the controller 30 acquires the zero cross timing t <b> 0 based on the zero cross signal output from the zero cross detection circuit 56. Note that S32 is an example of the first detection step, the second detection step, the first detection process, and the second detection process of the present invention.

  Next, in S33, the controller 30 acquires the output current value of the current sensor 55 from the zero cross timing t0 and sequentially differentiates the current value. Note that S33 is an example of the detection step and the detection process of the present invention. In addition, “differentiation” in the present embodiment refers to dividing (dividing) a difference between acquired discrete current values by a unit time.

  Next, in S34, the controller 30 detects a time t1 when the differential value becomes zero. Thereafter, the time PEAK_TIME is calculated from the difference between t1 and t0. Note that S34 corresponds to the third detection step, the specific time length measurement step, the third detection process, and the specific time length measurement process of the present invention, and the time PEAK_TIME is an example of the specific time of the present invention.

  Next, in S35, the controller 30 calculates the ratio that the time PEAK_TIME occupies in the AC half period (Tu), that is, the ratio α = (time PEAK_TIME / AC half period (Tu)) × 100.

  Specifically, in the case where the wiring impedance from the switchboard to the image forming apparatus is sufficiently low, when power is supplied to the image forming apparatus, particularly the fixing heater 82, as shown by the one-dot chain line in FIG. The output current value of the sensor 55 changes while drawing a sine waveform or a waveform close thereto. The differentiated result changes by drawing a cosine waveform or a waveform close thereto. Therefore, the differential waveform crosses zero at time t2, which is approximately the middle of the AC half cycle (Tu), that is, at a position of about 50%.

  However, when the wiring distance from the switchboard to the image forming apparatus is long, when the number of branches from one switchboard is large, or when facilities are aging, the wiring impedance from the switchboard to the image forming apparatus is large. There is an environment. When power is supplied to the image forming apparatus, particularly the fixing heater 82 under an environment where the wiring impedance is large, the peak of the output current value of the current sensor 55 tends to shift to the left as shown by the solid line in FIG. There is. In addition, the larger the wiring impedance, the larger the deviation amount.

  Therefore, the time when the differential value corresponding to the peak of the output current value of the current sensor 55 becomes zero is a position shifted to the left side of the time t2, that is, the time t1, as indicated by a broken line in FIG.

  As described above, in this embodiment, since the differential value of the supply current to the fixing heater 82 is used to determine the wiring impedance from the switchboard to the image forming apparatus, the peak of the supply current can be easily grasped, and the accuracy The wiring impedance from the switchboard to the image forming apparatus can be determined well.

  Next, in S36, the controller 30 determines whether or not the ratio α obtained in S35 is within a range of 45% or more and 55% or less. In S36, when the controller 30 determines that the ratio α is within the range of 45% or more and 55% or less (S36: YES), the wiring impedance from the switchboard to the image forming apparatus is normal ( Small). In the next S37, the controller 30 stores the level 0 in the RAM 33 or the NVRAM 34 and ends the process.

  In S36, the controller 30 may more preferably determine whether or not the ratio α is 50%. A range of 45% or more is an example of the first threshold value of the present invention, and a range of 55% or less is an example of the second threshold value of the present invention.

  On the other hand, if the controller 30 determines in S36 that the ratio α is not in the range of 45% to 55% (S36: NO), the wiring impedance from the switchboard to the image forming apparatus is abnormal ( Judgment is large). In the next S38, the controller 30 stores the level 1 in the RAM 33 or the NVRAM 34 and ends the process.

  As described above, according to the present exemplary embodiment, when the printer 100 is turned on, when the standby mode is shifted to the print mode, or when a new print job is started after one continuous print job is completed. There is a state where the fixing heater 82 is cold. In the state where the fixing heater 82 is cooled, the wiring impedance from the switchboard to the image forming apparatus is judged using the half-wave supply current of the first wave in energizing the fixing heater 82, so that the accuracy is high. It becomes possible to determine the wiring impedance from the switchboard to the image forming apparatus.

  That is, FIG. 8A shows a current waveform when power is supplied to the fixing heater by the 33% duty wave number control. The first-wave supply current waveform A in the energization to the fixing heater 82 is as follows. When the fixing heater 82 is cold, it becomes a large value due to the inrush current. Therefore, since the wiring impedance from the switchboard to the image forming apparatus is determined using this first large supply current waveform A, the wiring impedance from the switchboard to the image forming apparatus can be determined with high accuracy.

  In the case of 33% duty wave number control, as shown in FIG. 8A, power is supplied to the fixing heater after every half wave, so that the half wave is accurately extracted. Therefore, the capacity of the external power supply 411 can be determined with high accuracy.

  FIG. 8B shows a current waveform when the electric power is supplied to the fixing heater by the 33% duty wave number control after the phase control. Even in such a control method, there is a control method for the wave number control. The first supply current waveform B after the change has a large inrush current since the fixing heater 82 is still cold. Therefore, since the wiring impedance from the switchboard to the image forming apparatus is determined using the first supply current waveform B, the capacity of the external power supply 411 can be determined with high accuracy. In this case, 100% power supply control may be used instead of the 33% duty wave number control.

  Next, returning to the description of the control procedure shown in FIG. 5, in S18, the controller 30 determines whether or not the number of determination processes, that is, whether or not the value of the counter is larger than “N”. In the first process, since the number of determination processes is not greater than “N” (S18: NO), in the next S19, the controller 30 determines whether or not the determination level is “0”.

  In S19, when the controller 30 determines that the determination level is “0” (S19: YES), that is, in S36 shown in FIG. 6, the ratio α is 45% or more and 55% or less. If it is determined that the value falls within the range (S36: YES), in the next S20, the controller 30 stores the normal heater control in the RAM 33 or NVRAM 34, and then resets the counter value in the next S21. After that, the process ends.

Therefore, in S6 shown in FIG. 4 described above, the controller 30 supplies power to the fixing heater 82 by normal heater control.
In normal heater control, shortening of the first printout time (hereinafter abbreviated as FPOT) is regarded as important. The controller 30 performs wave number control in which the electric power from the external power supply 411 is energized or de-energized every half wave, specifically, high duty wave number control, more preferably, 100% duty wave number control. Conduct energization control. Alternatively, the controller 30 turns on the electric power from the external power supply 411 every half wave from the zero cross timing to a predetermined phase angle timing, specifically, phase control with a long on period, more preferably a phase angle of 0 degree. The energization control of the fixing heater 82 is performed by this phase control. Alternatively, the energization control of the fixing heater 82 may be performed by a control method combining them. This normal heater control is an example of the first control of the present invention.

  On the other hand, when the controller 30 determines in S19 that the determination level is not “0” (S19: NO), that is, in S36 shown in FIG. 6, the ratio α is 45% or more and 55%. If it is determined that it is not within the following range (S36: NO), in the next S23, the controller 30 stores the second heater control in the RAM 33 or the NVRAM 34, and proceeds to the next S24.

Therefore, in S6 shown in FIG. 4, the controller 30 supplies power to the fixing heater 82 by the second heater control.
This second heater control is a control corresponding to a higher wiring impedance from the switchboard to the image forming apparatus than to shorten the FPOT time. That is, when power supply to the image forming apparatus, in particular, the fixing heater 82 is started, so-called flicker phenomenon (flicker phenomenon) that occurs in a lighting device connected to the same switchboard is reduced, or visibility to the flicker phenomenon is reduced. The controller 30 controls energization with the energization pattern to be lowered. This makes it less susceptible to the flicker phenomenon.

  Therefore, the second heater control employs a 33% duty or 67% duty wave number control in order to avoid a frequency (about 10 Hz) at which human vision is likely to feel flicker.

  Further, in the second heater control, the energization control is performed such that the wave number control of 33% duty or 67% duty is performed for a predetermined time and then 100% energization is performed by wave number control or phase control. Accordingly, the warm-up time of the fixing heater 82 may be shortened. The predetermined time is an estimated time until the temperature of the filament of the halogen heater increases (becomes a high resistance state). After the predetermined time has elapsed, the influence of the resistance component of the halogen heater is strong and flicker is less likely to occur. Therefore, the heater warm-up can be completed earlier by increasing the energization amount to the heater.

  Further, as the second heater control, phase control is performed in which the power from the external power supply 411 is turned on every half wave from the zero cross timing to a predetermined phase angle, and the phase angle is 90 degrees or more, more preferably 150 degrees. The phase control may be performed at a degree or more. In the case of this phase control, by reducing the current supplied at one time, the voltage drop can be suppressed, and as a result, the flicker phenomenon hardly occurs.

  Therefore, the second control is an energization control that suppresses the occurrence of the flicker phenomenon or lowers the visual sensitivity to the flicker phenomenon than the first control. This second heater control is an example of the second control of the present invention.

  As described above, in this embodiment, when heating the heating roller 81, in S6 shown in FIG. 4, power is supplied to the fixing heater 82 based on the heater control method set in S20 and S23 shown in FIG. Therefore, in an environment where the wiring impedance from the switchboard to the image forming apparatus is large, when power supply is started to the image forming apparatus, particularly the fixing heater 82, a so-called flicker phenomenon (flicker phenomenon) that occurs in a lighting device connected to the same switchboard. Phenomenon) is reduced, or an energization pattern that lowers the visual sensitivity to the flicker phenomenon can be made less susceptible to the flicker phenomenon.

  Next, in S24, the controller 30 determines whether or not printing has been completed. If it is determined that printing has not ended (S24: NO), the controller 30 returns to S23 and continues until the printing is completed. The heater control is maintained. That is, the second heater control is maintained until printing of one sheet or printing of a plurality of continuous sheets is completed.

  On the other hand, if the controller 30 determines in S24 that printing has ended (S24: YES), the process returns to S13, and the controller 30 sequentially executes S13 to S16 again.

  Prior to the start of printing of a new print job, when the controller 30 energizes the switching element 50 to start energization of the fixing heater 82 in S6 of FIG. 4 described above, S15 and In S16, the controller 30 determines YES (S15: YES, S16: YES), and therefore the controller 30 executes the processes of S17 to S21 and S23 to S24 again.

  As described above, in this embodiment, the state of the wiring impedance from the switchboard to the image forming apparatus is confirmed again after a predetermined time by this process, and the first heater control or the second heater is determined according to the state of the wiring impedance. Electric power is supplied to the fixing heater 82 by the control. Therefore, the FPOT can be shortened according to the state of the wiring impedance, the flicker phenomenon (flicker phenomenon) can be reduced, or it can be made less susceptible to the flicker phenomenon.

  However, every time the controller 30 executes S17, the counter is incremented in S31 shown in FIG. 6. Therefore, when the controller 30 executes S17 N + 1 times, in S18, the controller 30 determines that the number of determination processes is “N”. (S18: YES), the controller 30 notifies an error in the next S22 and ends the process.

  That is, no electric power is supplied to the fixing heater 82. The notification of the error may be made by notifying the capacity shortage error of the external power supply 411 using a display on the operation panel 35 or a power supply abnormality lamp, or the wiring impedance from the switchboard to the image forming apparatus is large with a buzzer or the like. It does not matter if an error sound is issued. Note that “N” takes any one value from 3 to 10.

  Therefore, if the ratio α does not fall within the range of 45% or more and 55% or less N + 1 times consecutively, an abnormality in wiring impedance from the switchboard to the image forming apparatus is notified and power is supplied to the fixing heater 82. There is no. Therefore, it is possible to avoid a so-called flicker phenomenon (flickering phenomenon) that occurs in lighting equipment connected to the same switchboard when power supply to the image forming apparatus, particularly the fixing heater 82 is started.

(Embodiment 2)
FIG. 9 is a circuit diagram showing the electrical configuration of the power supply unit according to the second embodiment, and the details thereof will be described below with reference to FIG. In addition, in the description, the same code | symbol is attached | subjected and demonstrated to what has the same effect as Embodiment 1. FIG.

  That is, in the first embodiment, the zero cross detection circuit 56 detects the zero cross point of the external power supply 411 connected to the first input terminal 41 and outputs the zero cross signal to the controller 30 in real time. In the present embodiment, the zero cross point is detected based on the current value (current amount) from the current sensor 55.

  Therefore, in this embodiment, the current sensor 55 is disposed between the first input terminal 41 on the first line L1 and the first branch point P1, as shown in FIG. It is possible to measure the value of the alternating current flowing on one line L1, that is, the charging current to the smoothing capacitor 431 and the power supplied to the fixing heater 82 in addition to the charging current. The measured current value is output as a current sensor signal to the controller 30 via the second output terminal 47 and the third input terminal 48 in real time.

  Note that the current sensor 55 may be disposed between the first input terminal 41 on the second line L2 and the second branch point P2.

  FIG. 11 shows a waveform of a current value measured by the current sensor 55. When power is not supplied to the fixing heater 82 in the printing mode, the smoothing capacitor 431 is discharged by the power supplied to the controller 30 or the like, and the terminal voltage is lowered. Thereafter, when the voltage output from the rectifier circuit 42 exceeds the terminal voltage of the smoothing capacitor 431, the smoothing capacitor 431 is rapidly charged. Therefore, as shown on the left side of FIG. 11, the current value measured by the current sensor 55 changes while taking a steep pulse-like value spaced with time.

  Here, “charging” includes a charging process and / or full charging, and may also be referred to as capacitor input.

Further, in a state where power is supplied to the fixing heater 82 in the printing mode, in addition to the rapid charging current to the smoothing capacitor 431, the power supplied to the fixing heater 82 is combined.
Therefore, as shown on the right side of FIG. 11, the current value measured by the current sensor 55 generally changes in a sinusoidal waveform with the passage of time. In this case, the current value supplied to the fixing heater 82 is much larger than the charging current of the smoothing capacitor 431. Therefore, in the current waveform shown on the right side of FIG. Only the waveform due to the current supplied to the fixing heater 82 is visible.

  Further, in the sleep mode, the power output from the AC / DC converter 43 is not supplied to the 24V load, is supplied only to the controller 30, and further, the power is not supplied to the fixing heater 82. When the power is supplied to the controller 30, only the capacitor input current generated is mainly seen as a waveform.

FIG. 10 is a flowchart showing the control procedure of the zero-cross detection process, and the details of the zero-cross detection process will be described below with reference to FIG. Note that the control shown in FIG. 10 is executed by the controller 30 when the printer 100 is turned on or during the print mode period.
That is, in S51, the controller 30 continuously acquires the current value of the current sensor 55.

  Next, in S52, the controller 30 determines whether or not the fixing heater 82 is energized. If it is determined that power is being supplied (S52: YES), in S53, the controller 30 continuously acquires the current value of the current sensor 55, and at the timing when the acquired current value becomes zero. After detecting the zero cross point, the zero cross point stored in the RAM 33 or NVRAM 34 is updated, and the process is terminated.

  Specifically, while the fixing heater 82 is energized, the current sensor 55 also adds and measures the alternating current supplied to the fixing heater 82, so the current value output from the current sensor 55 is as shown in FIG. As shown on the right side, the value changes so as to swing up and down continuously with the passage of time. Therefore, the CPU 31 detects a point where the current value becomes zero (for example, indicated by P13 in FIG. 11) and sets it as a zero cross point (for example, indicated by Z2 in FIG. 11). As described above, while the fixing heater 82 is energized, S51 to S53 are sequentially executed, whereby the zero cross point Z2 stored in the RAM 33 or NVRAM 34 is sequentially updated to the latest zero cross point Z2.

  At this time, the timing when the current value becomes zero and the zero cross point Z2 are stored in the RAM 33 or the NVRAM 34 as elapsed time information (time stamp). The zero cross point Z2 is an example of the zero cross timing, and the zero cross timing may be stored in the RAM 33 or the NVRAM 34 as a time difference between the previously detected zero cross timing and the next (current) zero cross timing. .

  Note that the zero cross point Z2 stored in the RAM 33 or the NVRAM 34 is used in S14 shown in FIG. 5 in the same manner as the zero cross signal output from the zero cross detection circuit 56 of the first embodiment.

  In this embodiment, when the fixing heater 82 is energized, in S53, the current value of the current sensor 55 is continuously acquired, and the zero cross point is set based on the acquired current value of zero. However, the peak value of the current value output from the current sensor 55 (for example, indicated by P14 and P15 in FIG. 11) is detected, and the intermediate point thereof is the zero cross point (for example, indicated by Z3 in FIG. 11). And the zero cross point stored in the RAM 33 or the NVRAM 34 may be updated.

  On the other hand, if the controller 30 determines in S52 that it is not energized (S52: NO), the process proceeds to S54. In the next S54, the controller 30 continuously acquires the current value of the current sensor 55. Timing X1 is detected based on the acquired current value. This timing X1 is a timing at which the current value of the current sensor 55 exceeds the threshold value −α, as shown in FIG.

  Next, in S55, the controller 30 detects the timing X2 based on the acquired current value by continuously acquiring the current value of the current sensor 55. As shown in FIG. 12, the timing X2 is a timing at which the current value of the current sensor 55 falls below the threshold value −α.

Next, in S56, the controller 30 calculates the peak timing P11 shown in FIGS. 11 and 12 based on the detected timing X1 and timing X2. The peak timing P11 of the charging current value to the smoothing capacitor 431 can be detected by calculating the following equation.
P11 = X1 + (X2-X1) / 2

  Next, in S57, the controller 30 continuously acquires the current value of the current sensor 55 and detects the timing Y1 based on the acquired current value. This timing Y1 is a timing at which the current value of the current sensor 55 exceeds the threshold value α as shown in FIG.

  Next, in S58, the controller 30 detects the timing Y2 based on the acquired current value by continuously acquiring the current value of the current sensor 55. This timing Y2 is a timing when the current value of the current sensor 55 falls below the threshold value α as shown in FIG.

Next, in S59, the controller 30 calculates the peak timing P12 of the charging current value shown in FIGS. 11 and 12 based on the timing Y1 and the timing Y2. The peak timing P12 of the charging current value to the smoothing capacitor 431 can be detected by calculating the following equation.
P12 = Y1 + (Y2-Y1) / 2

Next, in S60, the controller 30 calculates the zero-cross point Z1 shown in FIGS. 11 and 12 based on the timing P11 of the charging current value peak and the timing P12 of the charging current value peak. This zero cross point Z1 can be detected by calculating the following equation.
Z1 = P11 + (P12-P11) / 2

  As described above, when power is not supplied to the fixing heater 82 in the printing mode, the zero cross point (for example, indicated by Z1 in FIGS. 11 and 12) changes with time. Based on the current value of 55, that is, the charging current to the smoothing capacitor 431, it is detected by sequential calculation. The zero cross point Z1 is stored in the RAM 33 or the NVRAM 34 as elapsed time information (time stamp). The zero cross point Z1 is an example of the zero cross timing, and the zero cross timing may be stored in the RAM 33 or the NVRAM 34 as a time difference between the previously detected zero cross timing and the next (current) zero cross timing. .

  Note that the zero-cross point Z1 stored in the RAM 33 or the NVRAM 34 is used in S14 shown in FIG. 5 in the same manner as the zero-cross signal output from the zero-cross detection circuit 56 of the first embodiment.

  In this embodiment, when detecting the peak of the current value measured by the current sensor, the current sensor 55 is used to detect the timing X1, the timing X2, the timing Y1, and the timing Y2 in S54, S55, S57, and S58 shown in FIG. The amount of change per unit time of the charging current value to the smoothing capacitor 431 measured by the current sensor 55 is obtained by comparing the charging current value to the smoothing capacitor 431 measured by the threshold value −α and the threshold value α. That is, the timing X1, the timing X2, the timing Y1, and the timing Y2 may be detected using the differential value, the threshold value Y, and the threshold value -Y.

  That is, the timing X1 is a timing at which the threshold value Y is reached (passed) only after the differential value of the current value of the current sensor 55 rises from zero. Timing X2 is the timing at which the differential value of the current value of the current sensor 55 reaches (passes) the threshold value -Y for the second time. The timing Y1 is a timing at which the differential value of the current value of the current sensor 55 reaches (passes) the threshold value Y. Furthermore, the timing Y2 is a timing at which the threshold value Y is reached for the second time after rising from zero. That is, in one charging waveform, there are two timings when the differential value of the current value passes the threshold value Y and the threshold value -Y, and among the four timings, X1 is the timing when the threshold value is first passed, and X2 Is the timing when the threshold value is finally passed.

  As described above, in this embodiment, since the zero cross detection circuit is not required, the configuration is simple, and the zero cross point is detected using the current value of the current sensor 55. It becomes possible to detect.

  In addition, this Embodiment is only a mere illustration and does not limit this invention at all. Therefore, the present invention can be variously improved and modified without departing from the scope of the invention. For example, the image forming apparatus is not limited to a printer, and can be applied as long as it has a function of forming an image by an electrophotographic method, such as a copier, a FAX apparatus, or a multifunction peripheral. The printer 100 according to the embodiment is a color printer and includes four process units 10K, 10C, 10M, and 10Y. However, the printer 100 may be a monochrome printer including one process unit.

  In the first embodiment, the current sensor 55 is used. However, as shown in FIG. 13, a voltage sensor 57 can be used instead of the current sensor 55. In that case, in S33-S34 shown in FIG. 6, it will process based on the voltage value output from an alternating current voltmeter.

  In the first embodiment, when the controller 30 determines in S18 shown in FIG. 5 that the determination level is not “0” (S19: NO), until the printing is completed (S24: YES), In S6 shown in FIG. 4, the controller 30 is configured to supply power to the fixing heater 82 by the second heater control. For example, the controller 30 supplies power to the fixing heater 82 by the second heater control for a certain period of time. Then, the setting is changed to normal heater control, and power is supplied to the fixing heater 82 by normal heater control, so that warm-up can be completed early.

  Further, in the first embodiment, the current sensor 55 is connected between the first input terminal 41 on the first line L1 and the first branch point P1, and between the first input terminal 41 on the second line L2 and the first input terminal 41. It may be arranged between two branch points P2. In this case, when power is supplied to the fixing heater 82, the current sensor 55 detects a combined current of the current supplied to the fixing heater 82 and the current supplied to the AC / DC converter 43. become. Since the current supplied to the fixing heater 82 is much larger than the current supplied to the AC / DC converter 43, in the present invention, this combined current can be regarded as the current supplied to the fixing heater 82 approximately.

DESCRIPTION OF SYMBOLS 100 Printer 6 Exposure device 8 Thermal fixing device 81 Heating roller 82 Fixing heater 83 Temperature sensor 30 Controller 31 CPU
40 power supply unit 41 first input terminal 42 rectifier circuit 43 AC / DC converter 50 switching element 55 current sensor 56 zero cross detection circuit 57 voltage sensors L1 to L4 first to fourth lines P1 to P2 first to second branches point

Claims (20)

A heater that receives power from an external power source;
A sensor that outputs different signals according to the amount of current or voltage supplied to the heater from the external power source; and
A controller,
With
The controller is
In a state where the heater is energized, a predetermined detection amount is detected by receiving a signal from the sensor,
Detect the timing when the detection amount becomes zero,
Detect the timing when the detected amount reaches a peak,
Measure the length of a specific time that is the time from the timing when the detected amount becomes zero to the timing when the detected amount reaches a peak,
Determining whether the length of the specific time is within a predetermined range or out of a predetermined range;
An image forming apparatus. The image forming apparatus according to claim 1,
The controller is
If the length of the specific time is within a predetermined range, a first control for controlling energization to the heater with a first energization pattern is executed,
If the length of the specific time is out of the predetermined range, the heater is energized with a second energization pattern that suppresses the occurrence of the flicker phenomenon or reduces the visibility to the flicker phenomenon as compared with the first control. Performing a second control to control,
An image forming apparatus. The image forming apparatus according to claim 1 or 2,
The controller is
The length of the specific time is measured when performing wave number control in which power from the external power source is energized or de-energized every half wave,
An image forming apparatus. The image forming apparatus according to claim 3.
The controller is
The length of the specific time is measured in the first half wave when the wave number control is performed.
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 4, wherein:
The controller is
Detecting the timing when the detected amount reaches a peak based on the timing when the differential value of the detected amount becomes 0;
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 5,
The controller is
When the length of the specific time is equal to or greater than the first threshold, the length of the specific time is within the predetermined range, and when the length of the specific time is less than the first threshold, the length of the specific time Is outside the predetermined range,
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 5,
The controller is
When the length of the specific time is greater than or equal to a first threshold and less than a second threshold that is longer than the first threshold, it is determined that the length of the specific time is within the predetermined range, and the length of the specific time Is less than the first threshold, or if the length of the specific time is greater than or equal to the second threshold, it is determined that the length of the specific time is outside the predetermined range.
An image forming apparatus. The image forming apparatus according to any one of claims 2 to 7,
The controller is
The second control is a wave number control in which the electric power from the external power supply is energized or de-energized every half wave, and the wave number control with the duty ratio of energization being 33% or 67% is performed.
An image forming apparatus. The image forming apparatus according to any one of claims 2 to 7,
The controller is
The second control is a phase control in which a current from the external power source is supplied at a timing of a predetermined phase angle from a timing at which the detection amount becomes zero every half wave, and the predetermined phase angle is set to 90 degrees. The phase control is performed as described above.
An image forming apparatus. The image forming apparatus according to any one of claims 2 to 9,
The controller is
When a predetermined time has elapsed after starting execution of the second control, the second control is switched to the first control.
An image forming apparatus. The image forming apparatus according to any one of claims 2 to 9,
The controller is
When a predetermined time has elapsed after starting the execution of the second control, the second control is terminated, and the length of the specific time is re-measured.
If the remeasured length of the specific time is within the predetermined range, the first control is executed,
If the length of the re-measured specific time is outside the predetermined range, the second control is executed.
An image forming apparatus. The image forming apparatus according to claim 11.
With a notification unit,
The controller is
Count the number of times the length of the specific time was measured,
When the count value exceeds the threshold number of times, the notification unit is controlled to notify an error.
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 12,
An AC input unit to which power from the external power source is input;
A converter having a rectifier circuit for rectifying an alternating current from the alternating current input unit, and a capacitor for smoothing the current from the rectifier circuit;
A first line that electrically connects the AC input unit and the converter;
A second line electrically connecting the branch point on the first line and the heater;
With
The controller is supplied with power converted by the converter,
The sensor is a current sensor and is disposed on the second line.
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 12,
An AC input unit to which power from the external power source is input;
A converter having a rectifier circuit for rectifying an alternating current from the alternating current input unit, and a capacitor for smoothing the current from the rectifier circuit;
A first line that electrically connects the AC input unit and the converter;
A second line electrically connecting the branch point on the first line and the heater;
With
The controller is supplied with power converted by the converter,
The sensor is a current sensor, on the first line, and disposed between the AC input unit and the branch point.
An image forming apparatus. The image forming apparatus according to claim 14.
The controller is
Detecting the charging timing of the capacitor based on the detected current value, and detecting the timing when the detection amount becomes zero based on the detected charging timing of the capacitor;
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 14,
A detection circuit for detecting a timing at which the electric power supplied to the heater becomes zero;
The controller is
Based on a signal output at a timing when the power supplied from the detection circuit to the heater becomes zero, a timing at which the detection amount becomes zero is detected.
An image forming apparatus. A heater that receives power from an external power source;
A sensor that outputs different signals according to the amount of current or voltage supplied to the heater from the external power source; and
A method of controlling the heater of an image forming apparatus comprising:
A first detection step of detecting a predetermined detection amount in response to a signal from the sensor in a state where the heater is energized;
A second detection step of detecting a timing at which the detection amount becomes zero;
A third detection step of detecting a timing at which the detection amount reaches a peak;
A specific time length measuring step for measuring a length of a specific time which is a time from a timing when the detected amount becomes zero to a timing when the detected amount reaches a peak, and an energizing step for controlling energization to the heater,
The heater control method comprising the energization step of determining whether the length of the specific time is within a predetermined range or outside the predetermined range. In the heater control method according to claim 17,
An energization step for controlling energization of the heater,
If the length of the specific time is within a predetermined range, a first control for controlling energization to the heater with a first energization pattern is executed,
If the length of the specific time is out of the predetermined range, the heater is energized with a second energization pattern that suppresses the occurrence of the flicker phenomenon or reduces the visibility to the flicker phenomenon as compared with the first control. Executing the second control to control, the energization step,
A method for controlling a heater, comprising: A heater that receives power from an external power source;
A sensor that outputs different signals according to the amount of current or voltage supplied to the heater from the external power source; and
An image forming apparatus comprising:
A first detection process for detecting a predetermined detection amount in response to a signal from the sensor in a state where the heater is energized;
A second detection process for detecting a timing at which the detection amount becomes zero;
A third detection process for detecting a timing at which the detection amount reaches a peak;
A specific time length measurement process for measuring a length of a specific time that is a time from a timing at which the detection amount becomes zero to a timing at which the detection amount reaches a peak, and an energization process for controlling energization to the heater,
Determining whether the length of the specific time is within a predetermined range or out of a predetermined range;
A program characterized by having executed. The program according to claim 19,
An energization process for controlling energization to the heater,
If the length of the specific time is within a predetermined range, a first control for controlling energization to the heater with a first energization pattern is executed,
If the length of the specific time is out of the predetermined range, the heater is energized with a second energization pattern that suppresses the occurrence of the flicker phenomenon or reduces the visibility to the flicker phenomenon as compared with the first control. Performing the second control to control, the energization process,
For causing the image forming apparatus to execute the program.

Images