JP2019203958A - Image forming apparatus and method for controlling image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can more reliably prevent the generation of an abnormal noise, and a method for controlling the image forming apparatus.SOLUTION: An image forming apparatus comprises: heaters H1 and H2; and a control unit 20 that controls a current supplied to the heater H1 through phase control for adjusting an on-phase angle and controls a current supplied to the heater H2 through inverse phase control. The control unit 20 acquires a resistance value of each of the heaters H1 and H2 on the basis of the time elapsed from complete turn-off of each of the heaters H1 and H2. When starting turn-on of each of the heaters H1 and H2 in a complete turned-off state, the control unit 20 determines each of the on-phase angle and an off-phase angle on the basis of the resistance value of each of the heaters H1 and H2 and a first threshold. The first threshold is the amount of variation in current at which the magnitude of an abnormal noise reaches a level at which the abnormal noise is inaudible to humans.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus and an image forming apparatus control method. More specifically, the present invention relates to an image forming apparatus provided with each of first and second heaters having different power consumption and a method for controlling the image forming apparatus.

  The electrophotographic image forming apparatus includes a scanner function, a facsimile function, a copying function, a function as a printer, a data communication function, and a server function, an MFP (Multi Function Peripheral), a facsimile apparatus, a copying machine, a printer, and the like. is there.

  Some electrophotographic image forming apparatuses form an electrostatic latent image by scanning a light beam from an optical writing device onto an image carrier. The image forming apparatus develops an electrostatic latent image using a developing unit to form a toner image, transfers the toner image to a sheet, and then fixes the toner image on the sheet by a fixing unit. Form.

  The image forming apparatus includes a heater for heating the fixing device. When the heater of the image forming apparatus is a halogen heater in particular, a large inrush current is generated in the heater when the heater is turned on. For this reason, a method is generally employed in which the inrush current to the heater is suppressed by performing phase control that adjusts the on-phase angle, which is the phase angle at which the supply of alternating current from the power source to the heater is started. When performing phase control, there is a problem in that abnormal noise is generated from an electrical component such as a choke coil because a switch for passing a current to the heater is turned on during the half-wave period of the AC waveform from the power supply.

  Therefore, a technique for suppressing abnormal noise generated when phase control is performed is proposed in Patent Document 1 below. In Patent Document 1 below, the phase control execution period is divided into two periods, a first stage period and the remaining second stage period. In the first stage period, no abnormal noise is generated or the abnormal noise generated is a predetermined volume. An image forming apparatus is disclosed in which energization is performed with an abnormal noise suppression duty ratio as described below, and energization is performed with a second duty ratio higher than the abnormal noise suppression duty ratio in the subsequent second stage period.

  Prior art relating to phase control is also disclosed in Patent Documents 2 and 3 below. Patent Document 2 below discloses a power control device that adjusts power supplied from an AC power source to a plurality of loads by phase control. The power control apparatus includes: a first switching unit that turns on / off power supply to a first load; a second switching unit that turns on / off power supply to a second load; and Phase control means for controlling the conduction angle. In the phase control section including a plurality of alternating half-waves, the phase control means turns off one of the two switching means and turns off the other to supply power to one of the first and second loads. Power is supplied to the third load when the switching means is turned OFF.

  Patent Document 3 below discloses a technique for controlling power supply to the sub heater by phase control and controlling power supply to the main heater by switching control. During switching control, the switching duty is switched at the timing of turning on the power supply to the sub heater in phase control so that the combined waveform of the current flowing through the sub heater and the current flowing through the main heater matches the sine wave. It is done.

JP2013-16781A JP 2010-186218 A Japanese Patent Laid-Open No. 2015-210276

  The conventional technique has a problem that it is not possible to reliably suppress abnormal noise generated when phase control is performed. In particular, the technique of Patent Document 1 limits the time during which sound is generated only to the second stage period, and cannot sufficiently suppress the generation of sound during the second stage period. Further, even during the first stage period, a current larger than expected may flow through the heater due to fluctuations in the resistance value of the heater, and there is a risk that an abnormal sound may be heard by the human ear. The office environment in recent years is quiet, and it is necessary to reliably suppress abnormal noise, assuming that the image forming apparatus is installed in such an environment.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus and an image forming apparatus control method that can more reliably suppress the generation of abnormal noise.

  An image forming apparatus according to an aspect of the present invention includes a first and a second heater having different power consumptions, a storage unit that stores a first threshold value related to a variation amount of current, and a first and a second heater. Acquisition means for acquiring the resistance value of each of the first and second heaters based on the elapsed time from the complete extinction of each of the heaters, and an on-phase which is a phase angle for starting supply of alternating current from the power source The second heater is controlled by the anti-phase control that controls the current supplied to the first heater by the phase control for adjusting the angle and the off-phase angle that is the phase angle for stopping the supply of the alternating current from the power source. Control means for controlling the current supplied to the first and second heaters obtained by the obtaining means when starting lighting of each of the first and second heaters in a completely extinguished state. Heater And a first control means for determining each of the on-phase angle and the off-phase angle based on the first threshold value, and the first threshold value is applied to the first heater at the on-phase angle. A level at which humans cannot hear the magnitude of abnormal noise caused by fluctuations in the flowing current and the magnitude of abnormal noise caused by fluctuations in the current flowing through the second heater at the off phase angle. Is the amount of current fluctuation.

  Preferably, in the image forming apparatus, the first control unit causes the second heater to generate a noise that is generated due to a fluctuation in the current flowing through the first heater at the on-phase angle, and to the second heater at the off-phase angle. The values at which the magnitudes of allophones generated due to fluctuations in the flowing current are both within a predetermined range are determined as the on phase angle and the off phase angle.

  In the image forming apparatus, the power consumption of the first heater is preferably larger than the power consumption of the second heater.

  Preferably, in the image forming apparatus, the storage unit stores a plurality of threshold values related to the amount of fluctuation of the current, and includes a plurality of threshold values including the first threshold value. In response, based on the selection means for selecting a threshold value from a plurality of threshold values, the resistance values of the first and second heaters acquired by the acquisition means, and the threshold value selected by the selection means. Determining means for determining each of the phase angle and the off-phase angle.

  Preferably, the image forming apparatus further includes a printing unit that performs printing on the printing medium, and the selection unit starts to turn on during printing by the printing unit than the first threshold value among the plurality of threshold values. Choose a large second threshold.

  Preferably, the image forming apparatus further includes a fixing unit that is heated by the first and second heaters, and the selection unit starts lighting during warm-up to heat the fixing unit in a paused state to a predetermined temperature. In addition, a third threshold value larger than the first threshold value is selected from the plurality of threshold values.

  Preferably, the image forming apparatus further includes a sound sensor that acquires sound in the vicinity of the image forming apparatus, and the selection unit is turned on in a state where the volume of the sound acquired by the sound sensor exceeds the first level. When starting, a fourth threshold value larger than the first threshold value is selected from the plurality of threshold values.

  Preferably, in the image forming apparatus, the selection unit has a plurality of threshold values when lighting is started in a state where the volume of sound acquired by the sound sensor exceeds a second level that is larger than the first level. A fifth threshold value larger than the fourth threshold value is selected.

  Preferably, the image forming apparatus further includes a human sensor that senses a person around the image forming apparatus, and the selection unit has a plurality of threshold values when lighting is started without the human sensor detecting the human. A sixth threshold value larger than the first threshold value is selected.

  Preferably, in the image forming apparatus, the storage unit further stores an effective value threshold that is a threshold of an effective value of a current that flows while each of the first and second heaters is turned on, and the effective value threshold is: The voltage drop amount of the power source generated due to the current flowing through the first and second heaters is a value that falls within a predetermined range, and the first control means is the first and second heaters in a completely extinguished state. When the lighting of each of these is started, each of the on phase angle and the off phase angle is determined further based on the effective value threshold value.

  Preferably, in the image forming apparatus, an illuminance sensor that detects illuminance of an environment in which the image forming apparatus is installed, and an illuminance sensor when lighting is started at an on phase angle and an off phase angle determined based on an effective value threshold When the lighting device starts the next lighting when the lighting device detects that there is no variation in illuminance detected by the illuminance sensor. And a redetermination unit that determines each of the on phase angle and the off phase angle based on another effective value threshold value that is a large value.

  Preferably, the image forming apparatus further includes a temperature sensor that acquires information on a temperature in a room in which the image forming apparatus is installed, and the acquisition unit further includes first and second information based on the information acquired by the temperature sensor. Get the resistance value of each heater.

  Preferably, in the image forming apparatus, the first control unit is configured to gradually increase a ratio of time for supplying current to each of the first and second heaters as time elapses after starting lighting. Each of the on phase angle and the off phase angle is determined.

  Preferably, in the image forming apparatus, the control unit sets the temperature of the fixing unit heated by the first and second heaters when starting lighting of each of the first and second heaters that are completely turned off. Accordingly, the second control means for determining each of the on phase angle and the off phase angle, and the elapsed time from the complete extinguishing of the first and second heaters at the start of lighting of the first and second heaters are predetermined. If the time is less than the time, the control by the first control means is selected, and the elapsed time from the complete turn-off of the first and second heaters exceeds the predetermined time at the start of lighting of the first and second heaters In the case, it further includes control selection means for selecting control by the second control means, and the second control means is configured such that the temperature of the fixing device is the first temperature from the start of lighting of the first and second heaters. Until you reach In the meantime, the current supplied to each of the first and second heaters is gradually increased, and the second control means is higher than the first temperature after the temperature of the fixing device reaches the first temperature. Until the second temperature is reached, the on-phase angle and the off-phase angle are gradually decreased while keeping the on-phase angle and the off-phase angle at the same value. The on-phase angle and the off-phase angle are kept at a predetermined phase angle from when the first temperature reaches the second temperature until the third temperature higher than the second temperature is reached.

  According to another aspect of the present invention, a method for controlling an image forming apparatus includes first and second heaters having different power consumptions, and a storage unit that stores a first threshold value related to a current fluctuation amount. An image forming apparatus control method, wherein an acquisition step of acquiring a resistance value of each of the first and second heaters based on an elapsed time from the complete extinction of each of the first and second heaters, and a power source This is a phase angle that controls the current supplied to the first heater and stops the supply of AC current from the power source by phase control that adjusts the ON phase angle, which is the phase angle at which supply of AC current from the power source is started A control step for controlling a current supplied to the second heater by reverse phase control for adjusting the off-phase angle, and the control step turns on each of the first and second heaters in a completely extinguished state. When starting, a first control step of determining each of the on phase angle and the off phase angle based on the resistance values of the first and second heaters acquired in the acquisition step and the first threshold value And the first threshold value is due to the magnitude of the abnormal noise generated due to the fluctuation of the current flowing through the first heater at the on-phase angle and the fluctuation of the current flowing through the second heater at the off-phase angle. The magnitude of the abnormal noise generated in this way is the amount of fluctuation in the current at a level that cannot be heard by humans.

  According to the present invention, it is possible to provide an image forming apparatus and an image forming apparatus control method capable of more reliably suppressing the occurrence of abnormal noise.

1 is a cross-sectional view schematically showing a configuration of an image forming apparatus 1 according to an embodiment of the present invention. 1 is a diagram illustrating a heater drive circuit (fixing lighting circuit) in an image forming apparatus 1 according to an embodiment of the present invention. FIG. It is a figure which shows the lighting control circuit of the heater in the image forming apparatus 1 of one embodiment of this invention. It is a figure which shows typically the phase control which the control part 20 performs in one embodiment of this invention. It is a figure which shows typically the antiphase control which the control part 20 performs in one embodiment of this invention. It is a figure explaining the principle which abnormal noise generate | occur | produces. It is a figure which shows the resistance value table which ROM22 memorize | stores in one embodiment of this invention. It is a figure which shows the relationship between the on phase angle (theta) 1 and off phase angle (theta) 2 which are calculated in one embodiment of this invention, and the rated power consumption of a heater. It is a figure which shows typically the lighting control according to the sound suppression reference | standard table in one embodiment of this invention. 3 is a flowchart showing a basic operation of the image forming apparatus 1 according to an embodiment of the present invention. 3 is a flowchart showing an operation of the image forming apparatus 1 including an operation at the time of printing in an embodiment of the present invention. 4 is a flowchart showing an operation of the image forming apparatus 1 including an operation at the time of warm-up in an embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  In the following embodiment, a case where the image forming apparatus is an MFP will be described. The image forming apparatus may be a printer, a facsimile machine, a copying machine, or the like in addition to the MFP.

  [Configuration of Image Forming Apparatus]

  First, the configuration of the image forming apparatus in the present embodiment will be described.

  FIG. 1 is a cross-sectional view schematically showing a configuration of an image forming apparatus 1 according to an embodiment of the present invention.

  Referring to FIG. 1, image forming apparatus 1 in the present embodiment prints an image on sheet-like print medium M (for example, paper). The image forming apparatus 1 includes a paper feeding unit 2, a registration roller 3, an image forming unit 4, a fixing device 5, an operation panel (operation / input unit) 6, heaters H1 and H2 (first and second). An example of a heater).

  An unused print medium M is stacked on the paper feed unit 2. The paper feed unit 2 feeds the print medium M one by one to the transport path TR indicated by a broken line in FIG.

  The registration roller 3 is provided on the downstream side of the paper feeding unit 2 on the transport path TR. The registration roller 3 temporarily stops the printing medium M fed from the paper feeding unit 2 and then sends it to the secondary transfer region ST at a predetermined timing.

  The image forming unit 4 and the fixing device 5 (an example of a printing unit) perform printing on the transported print medium M. The image forming unit 4 generates a toner image on the intermediate transfer belt by, for example, a well-known electrophotographic method and tandem method. Such a toner image is carried by the intermediate transfer belt and conveyed toward the secondary transfer region ST. The printing medium M is sent from the registration roller 3 to the secondary transfer region ST, and the toner image is conveyed from the image forming unit 4. In the secondary transfer region ST, the toner image is transferred from the intermediate transfer belt to the print medium M.

  The fixing device 5 fixes the toner image on the print medium M by transporting the print medium M on which the toner image is formed along the transport path TR. The print medium M that has passed through the fixing device 5 is discharged to the outside of the image forming apparatus 1.

  The heaters H1 and H2 are, for example, halogen heaters, and heat the fixing device 5 to a necessary temperature. The power consumption of the heater H1 and the power consumption of the heater H2 are different from each other, and the power consumption of the heater H1 is larger than the power consumption of the heater H2.

  The operation panel 6 accepts various operations and displays various information.

  FIG. 2 is a diagram showing a heater driving circuit (fixing lighting circuit) in the image forming apparatus 1 according to the embodiment of the present invention.

  Referring to FIG. 2, image forming apparatus 1 further includes a control unit 20 (an example of an acquisition unit and a control unit), switch units 30 a and 30 b, and a choke coil 34.

  The heaters H1 and H2 are connected in parallel to the commercial power supply 11 (for example, AC 100V). A choke coil 34 and a switch unit 30a are connected in series between the commercial power supply 11 and the heater H1. A choke coil 34 and a switch unit 30b are connected in series between the commercial power supply 11 and the heater H2.

  The control unit 20 controls the current I1 flowing through the heater H1 by controlling on / off of the switch unit 30a by the heater remote signal REM1. The control unit 20 controls the current I2 flowing through the heater H2 by controlling on / off of the switch unit 30b by the heater remote signal REM2.

  A current I3 that is a choke coil current flows through the choke coil 34. Current I3 has a magnitude corresponding to the sum of currents I1 and I2.

  FIG. 3 is a diagram showing a heater lighting control circuit in the image forming apparatus 1 according to the embodiment of the present invention.

  Referring to FIG. 3, the image forming apparatus 1 includes a main substrate SB1, a low voltage power supply substrate SB2, a temperature detection unit 24, an environmental sensor 25, a line filter 31, a secondary power supply 32, and a zero cross detection circuit. 33.

  On the main substrate SB1, a control unit 20, a temperature detection unit 24 of the fixing device 5, an environmental sensor 25, and heaters H1 and H2 are mounted.

  The control unit 20 includes a CPU (Central Processing Unit) 21 that controls the entire image forming apparatus 1 according to the control program, a ROM (Read Only Memory) 22 (an example of a storage unit) that stores the control program, and a work area of the CPU 21. It comprises a RAM (Random Access Memory) 23 and the like.

  The control unit 20 starts turning on the heaters H1 and H2 when the power of the image forming apparatus 1 is turned on or when the image forming apparatus 1 starts a job, and performs phase control or reverse phase control, which will be described later. . The control unit 20 shifts to predetermined lighting control after performing the phase control and the antiphase control. The control unit 20 turns on the heaters H1 and H2 until the temperature of the fixing device 5 satisfies the target temperature, and performs fixing temperature control control to turn off the heaters H1 and H2 when the temperature of the fixing device 5 reaches the target temperature. Do. The controller 20 controls the heaters H1 and H2 to control abnormal noise (such as sound suppression lighting control and lighting control according to a sound suppression reference table, which will be described later), and other general lighting controls. Switch between each other.

  The temperature detection unit 24 detects the temperature of the fixing device 5 and outputs the detection result to the control unit 20.

  The environment sensor 25 detects various information related to the environment around the image forming apparatus 1 and outputs the detection result to the control unit 20. The environment sensor 25 is a sound sensor 25a that acquires sound in the vicinity of the image forming apparatus 1, a human sensor 25b that senses people around the image forming apparatus 1, and the brightness of the environment in which the image forming apparatus 1 is installed. An illuminance sensor 25c to be detected and a temperature sensor 25d to acquire information on the temperature of the room in which the image forming apparatus 1 is installed are included.

  A line filter 31, a secondary power supply 32, and a zero cross detection circuit 33 are mounted on the low voltage power supply board SB2. The line filter 31 is for removing noise, and is provided between the switch units 30 a and 30 b and the commercial power supply 11.

  The secondary power supply 32 is connected to the commercial power supply 11 through an outlet. The secondary power supply 32 supplies power to the control unit 20. The secondary power supply 32 includes a switching circuit that converts the power from the commercial power supply 11 into a form suitable for supply (for example, a direct current having a predetermined voltage).

  The zero cross detection circuit 33 detects the timing when the alternating current supplied from the commercial power supply 11 becomes zero, and outputs the detection result to the control unit 20 as a zero cross signal.

  Each of switch units 30a and 30b turns on and off the energization path according to each of heater remote signals REM1 and REM2 output from control unit 20. Thereby, the supply of current to each of the heaters H1 and H2 is controlled.

  [Phase control and anti-phase control performed by the control unit 20]

  FIG. 4 is a diagram schematically showing phase control performed by the control unit 20 in the embodiment of the present invention.

  Referring to FIG. 4, control unit 20 controls the current supplied to heater H1 by phase control. The phase control is a control method for adjusting an on phase angle that is a phase angle at which supply of an alternating current from the commercial power supply 11 is started. Specifically, the control unit 20 stops the supply of current to the heater H1 at the timing when the AC current supplied from the commercial power supply 11 becomes zero, and the phase angle of the AC current supplied from the commercial power supply 11 is the ON phase angle. The supply of current to the heater H1 is started at the timing when θ1 is reached. The control unit 20 performs phase control in a cycle (range of 0 to 180 ° phase angle) corresponding to a half cycle of the alternating current from the commercial power supply 11.

  When the supply of current to the heater H1 is started at the on phase angle θ1, the absolute value of the fluctuation amount of the current flowing through the heater H1 is defined as a peak current I1p. When phase control is performed, the effective value of the current flowing through the heater H1 is a value obtained by multiplying the current value I1m whose absolute value is a maximum within a phase angle range of 0 ° to 180 ° by (1 / √2). It becomes.

  As shown in FIG. 4A, when the on phase angle θ1 is greater than 90 ° and less than 180 °, the peak current I1p and the current value I1m at which the absolute value is maximized coincide with each other.

  As shown in FIG. 4B, when the on phase angle θ1 is greater than 0 ° and equal to or less than 90 °, the current value I1m having the maximum absolute value is the current value when the phase angle is 90 °. . The peak current I1p is smaller than the current value I1m at which the absolute value is maximized.

  As shown in FIG. 4C, when the ON phase angle θ1 is 0 °, current is always supplied to the heater H1, and the heater H1 is completely lit. The peak current I1p is zero. The current value I1m having the maximum absolute value is the current value when the phase angle is 90 °.

  When the on phase angle θ1 is 180 °, the heater H1 is completely turned off, and the peak current I1p and the current value I1m are both zero.

  When performing the sound suppression lighting control to be described later, the control unit 20 starts lighting by gradually decreasing the ON phase angle θ1 as shown in FIG. 4A → FIG. 4B → FIG. 4C. As the time elapses, the ratio of the time for supplying current to the heater H1 is gradually increased, and finally the heater H1 is completely lit.

  FIG. 5 is a diagram schematically illustrating the anti-phase control performed by the control unit 20 in the embodiment of the present invention.

  Referring to FIG. 5, control unit 20 controls the current supplied to heater H <b> 2 by reverse phase control. The reverse phase control is a control method for adjusting an off phase angle that is a phase angle at which the supply of the alternating current from the commercial power supply 11 is stopped. Specifically, the control unit 20 starts supplying current to the heater H2 at a timing when the alternating current supplied from the commercial power supply 11 becomes zero, and the phase angle of the alternating current supplied from the commercial power supply 11 is the off phase angle. The supply of current to the heater H2 is stopped at the timing when it becomes θ2. The control unit 20 performs antiphase control at a period (range of 0 to 180 ° phase angle) corresponding to a half period of the alternating current from the commercial power supply 11.

  The fluctuation amount of the current flowing through the heater H2 when the supply of current to the heater H2 is stopped is defined as a peak current I2p. The effective value of the current flowing through the heater H2 in the case of performing the anti-phase control is obtained by multiplying the current value I2m having the maximum absolute value within the phase angle range of 0 ° to 180 ° by (1 / √2). Value.

  As shown in FIG. 5A, when the off-phase angle θ2 is greater than 0 ° and less than 90 °, the magnitude of the peak current I2p coincides with the current value I2m at which the absolute value is maximized.

  As shown in FIG. 5B, when the off phase angle θ2 is 90 or more and less than 180 °, the current value I2m having the maximum absolute value is the current value when the phase angle is 90 °. . The peak current I2p is smaller than the current value I2m at which the absolute value is maximized.

  As shown in FIG. 5C, when the off phase angle θ2 is 180 °, current is always supplied to the heater H2, and the heater H2 is completely lit. The peak current I2p is zero. The current value I2m having the maximum absolute value is the current value when the phase angle is 90 °.

  When the off phase angle θ2 is 0 °, the heater H2 is completely turned off, and the peak current I2p and the current value I2m are both zero.

  When performing the sound suppression lighting control described later, the control unit 20 starts lighting by gradually increasing the off phase angle θ2 as shown in FIG. 5A → FIG. 5B → FIG. 5C. As the time elapses, the ratio of the time for supplying current to the heater H2 is gradually increased, and finally the heater H2 is completely turned on (or completely turned off).

  [Principle of abnormal noise]

  FIG. 6 is a diagram for explaining the principle that abnormal noise occurs. FIG. 6A is a diagram schematically showing the configuration of the choke coil 34. FIG. 6B is a diagram showing the peak current I1p in the phase control. FIG. 6C is a diagram showing the peak current I2p in the antiphase control.

  Referring to FIG. 6, choke coil 34 includes a core 34a and a winding 34b. The iron core is, for example, annular. The winding 34b is a portion through which a current flows, and is wound around the core 34a.

  When the peak current I1p of the heater H1 is not zero (in other words, when the on phase angle θ1 is not 0 ° and 180 °), the current flowing through the choke coil 34 immediately after the start of power supply to the heater H1 is Increases rapidly. Similarly, when the peak current I2p of the heater H2 is not zero (in other words, when the off phase angle θ2 is not 0 ° or 180 °), immediately after the supply of power to the heater H2 is stopped, the choke coil 34 The flowing current decreases rapidly.

  When the current flowing through the choke coil 34 changes, a repulsive force is generated between the core 34a and the winding 34b, and the core 34a and the winding 34b vibrate due to this action. This vibration causes abnormal noise generated by the choke coil 34. As each of the peak current I1p of the heater H1 and the peak current I2p of the heater H2 is larger, the vibration of the choke coil 34 is increased, and thus the generated abnormal noise is increased.

  By the way, the resistance value of the heater greatly varies depending on the temperature of the heater. Usually, as the elapsed time after the heater is completely turned off increases, the temperature of the heater decreases and the resistance value of the heater decreases.

  Therefore, when starting lighting of each of the heaters H1 and H2 that are completely turned off, the control unit 20 performs sound suppression lighting control based on the resistance values of the heaters H1 and H2.

  [Sound and flicker suppression lighting control]

  Next, sound and flicker suppression lighting control will be specifically described.

  The control unit 20 calculates (acquires) the respective resistance values of the heaters H1 and H2 based on the elapsed time since the heaters H1 and H2 are completely turned off. Then, the control unit 20 turns on the lighting at the start of lighting based on the calculated resistance values of the heaters H1 and H2, the threshold value TH1 (an example of the first threshold value) and the effective value threshold value ET stored in the ROM 22. Each of the phase angle θ1 and the off phase angle θ2 is determined. The on-phase angle θ1 at the start of lighting is the on-phase angle at the first wave when the supply of alternating current from the commercial power supply 11 is started, and the off-phase angle θ2 at the start of lighting is the alternating current from the commercial power supply 11 This is the off phase angle at the first wave where the supply of current starts.

  The threshold value TH1 is a threshold value of the peak currents I1p and I2p. As the threshold value TH1, the magnitude of the abnormal noise generated due to the fluctuation of the current flowing through the heater H1 at the on phase angle θ1, and the abnormal noise generated due to the fluctuation of the current flowing through the heater H2 at the off phase angle θ2. The amount of fluctuation in current (peak current value) is set such that the magnitude of each is a level that cannot be heard by humans. The effective value threshold value ET is a threshold value of the effective value of the current that flows while each of the heaters H1 and H2 is on. The effective value threshold ET is a value in which the amount of voltage drop of the commercial power supply 11 caused by the current flowing through the heaters H1 and H2 falls within a predetermined range (light flickering of a lighting fixture that receives current supply from the commercial power supply 11) Is set so that at least flicker is suppressed to the extent that a person does not feel flicker.

  FIG. 7 is a diagram showing a resistance value table stored in the ROM 22 in the embodiment of the present invention.

  Referring to FIG. 7, in the resistance value table, when the rated power consumption of the heater is 230 W, 950 W, 790 W, and 357 W, respectively, the resistance value (Ω) when the heater is sufficiently cooled, the heater is warmed Resistance value Rf (Ω) at the time of heating, resistance value (Ω) 10 seconds after the heater is completely turned off, change amount of resistance value (Ω) 10 seconds after the heater is completely turned off, and resistance per second A change amount ΔR (Ω / s) of the value is described. Of these values, the resistance value (Ω) when the heater is sufficiently cooled, the resistance value Rf (Ω) when the heater is warmed, and the resistance value (Ω) after 10 seconds have elapsed since the heater is completely turned off. It is an experimental value. The amount of change in resistance value (Ω) and the amount of change in resistance value ΔR per second (Ω / s) in 10 seconds after the heater is completely turned off are values calculated based on the above experimental values. For example, when the rated power consumption of the heater is 230 W, the change amount ΔR of the resistance value per second of the heater is “−3.0 (Ω / s)”.

  When the heaters H1 and H2 are completely turned off, the control unit 20 counts the elapsed time since the heaters H1 and H2 are completely turned off.

  At the start of lighting of the heaters H1 and H2, the control unit 20 determines the amount of change ΔR of the resistance value per second of the heater H1 and the resistance value Rf when the heater H1 is warmed based on the rated power consumption of the heater H1. Are extracted from the resistance value table. Further, the control unit 20 changes the resistance value ΔR of the heater H2 per second and the resistance value when the heater H2 is warmed based on the rated power consumption of the heater H2 when the heaters H1 and H2 are turned on. Rf is extracted from the resistance value table. Further, the control unit 20 extracts the count value of the elapsed time as the elapsed time t at the start of lighting of the heaters H1 and H2.

  Subsequently, the control unit 20 calculates the resistance value R1 of the heater H1 at the start of lighting using the following formula (1), and calculates the resistance value R2 of the heater H2 at the start of lighting using the following formula (2). . In the following equation (1), the change amount ΔR1 is a change amount of the resistance value of the heater H1 per second, and the resistance value R1f is a resistance value when the heater H1 is warmed. In the following equation (2), the change amount ΔR2 is the change amount of the resistance value of the heater H2 per second, and the resistance value R2f is the resistance value when the heater H2 is warmed.

  Resistance value R1 = R1f + t × ΔR1 (1)

  Resistance value R2 = R2f + t × ΔR2 (2)

  Next, the control unit 20 calculates the ranges of the on phase angle θ1 and the off phase angle θ2 using the following equations (3) and (4) based on the resistance values R1 and R2, respectively. The control unit 20 determines each of the on phase angle θ1 and the off phase angle θ2 at the start of lighting to a value within the calculated range.

  Threshold TH1 ≧ sin (π / 180 × θ1) × 100 × √2 / R1 (3)

  Threshold TH1 ≧ sin (π / 180 × θ2) × 100 × √2 / R2 (4)

  The on-phase angle θ1 and the off-phase angle θ2 determined using the equations (3) and (4) are magnitudes of abnormal noise generated due to fluctuations in the current flowing through the heater H1 at the on-phase angle θ1, and The magnitude of the abnormal noise generated due to the fluctuation of the current flowing through the heater H2 at the off phase angle θ2 is within a predetermined range that cannot be heard by humans. Further, by determining the on-phase angle θ1 and the off-phase angle θ2 so that the effective value of the current flowing while each of the heaters H1 and H2 is on is equal to or less than the effective value threshold ET, the heaters H1 and H2 are The amount of voltage drop of the commercial power supply 11 caused by the flowing current does not cause the light flickering of the lighting fixture that receives the current supply from the commercial power supply 11 (at least the flicker is suppressed to the extent that a person does not feel the flicker). I) Within a predetermined range.

  Formulas (3) and (4) are obtained by the following method.

  The AC voltage Vpp of the commercial power supply 11 when the effective value of the AC voltage of the commercial power supply 11 is 100 V and the phase angle is the phase angle θ (°) is expressed by the following equation (5).

  AC voltage Vpp = sin (π / 180 × θ) × 100 × √2 (5)

  When the resistance value of the heater is the resistance value R, the current App flowing through the heater is expressed by the following formula (6).

  Current App = Vpp / R = sin (π / 180 × θ) × 100 × √2 / R (6)

  By substituting the on-phase angle θ1 into the phase angle θ and substituting the resistance value R1 of the heater H1 into the resistance value R in the equation (6), the peak current I1p at the start of lighting of the heater H1 is expressed by the following equation (7) It is represented by In Expression (6), the on-phase angle θ2 is substituted for the phase angle θ and the resistance value R2 of the heater H2 is substituted for the resistance value R, whereby the peak current I2p at the start of lighting of the heater H2 is represented by the following Expression (8 ).

  Peak current I1p = sin (π / 180 × θ1) × 100 × √2 / R1 (7)

  Peak current I2p = sin (π / 180 × θ2) × 100 × √2 / R2 (8)

  By the way, at the start of lighting of the heater H1, in order to make the magnitude of the abnormal noise generated due to the fluctuation of the current flowing through the heater H1 at the on phase angle θ1 at a level that cannot be heard by humans, The peak current I1p must satisfy the following formula (9). Further, at the start of lighting of the heater H2, in order to make the magnitude of the abnormal noise generated due to the fluctuation of the current flowing through the heater H2 at the off phase angle θ2 at the start of lighting of the heater H2, the level at which the heating of the heater H2 starts. The peak current I2p needs to satisfy the following formula (10).

  Threshold TH1 ≧ peak current I1p (9)

  Threshold TH1 ≧ peak current I2p (10)

  By substituting equation (7) into the peak current I1p of equation (9), equation (3) is obtained. Moreover, Formula (4) is obtained by substituting Formula (8) into the peak current I2p of Formula (10).

  FIG. 8 is a diagram showing the relationship between the on phase angle θ1 and the off phase angle θ2 calculated in the embodiment of the present invention, and the rated power consumption of the heater.

  Referring to FIG. 8, line LN1a is a line indicating a phase angle at which peak current I1p becomes equal to threshold value TH1 (here, 6.5 A). The region RG1 is a region having a phase angle larger than the phase angle indicated by the line LN1a, the peak current I1p is 6.5 A or less, and the effective value of the current flowing through the heater H1 is 7.5 A or more effective value threshold ET (here In this case, the region is 26.5 A) or less.

  By setting the ON phase angle θ1 at the start of lighting of the heater H1 within the range of the region RG1, the magnitude of the abnormal noise generated at the time of phase control at the start of lighting of the heater H1 becomes a level that cannot be heard by humans. In addition, no flickering of light occurs in the lighting fixture that receives the supply of current from the commercial power supply 11. At least flicker is suppressed to the extent that a person does not feel flicker.

  The line LN1b is a line indicating a phase angle at which the peak current I2p becomes equal to the threshold value TH1. Region RG5 is a region where the phase angle is smaller than the phase angle indicated by line LN1b, the peak current I2p is 6.5 A or less, and the effective value of the current flowing through heater H2 is 7.5 A or more.

  By setting the off phase angle θ2 at the start of lighting of the heater H2 within the range of the region RG5, the level of the abnormal noise generated at the time of reverse phase control at the start of lighting of the heater H2 cannot be heard by humans. Thus, no flickering of light occurs in the lighting fixture that receives the supply of current from the commercial power supply 11. At least flicker is suppressed to the extent that a person does not feel flicker.

  The ROM 22 may store a plurality of threshold values TH1, TH2, TH3, TH4 (TH1 <TH2 <TH3 <TH4) including a threshold value TH1, which are a plurality of threshold values related to a current fluctuation amount. Each of the plurality of threshold values TH1, TH2, TH3, TH4 is a value calculated by experiment.

  A line LN2 is a line indicating a phase angle at which the peak currents I1p and I2p are equal to the threshold value TH2. Region RG2 is a region where the phase angle is larger than the phase angle indicated by line LN2, peak currents I1p and I2p are 7A or less, and the effective value of the current flowing through each of heaters H1 and H2 is effective value threshold ET or less. It is an area.

  By setting the ON phase angle θ1 at the start of lighting of the heater H1 within the range of the region RG2, a level at which a human can slightly hear the magnitude of abnormal noise generated during phase control at the start of lighting of the heater H1. Thus, no flickering of light occurs in the lighting fixture that receives the supply of current from the commercial power supply 11. At least flicker is suppressed to the extent that a person does not feel flicker.

  A line LN3 is a line indicating a threshold value TH3 that is a voltage drop (here, 7 V) that causes light flickering of a lighting fixture that is supplied with current from the commercial power supply 11. Region RG3 is a region having a phase angle larger than the phase angle indicated by line LN3 and smaller than the phase angle indicated by line LN2. In the region RG3, when the phase angle in this region is set as the on phase angle θ1 or the off phase angle θ2, the voltage drop of the commercial power supply 11 is 7 V or less, and the effective value of the current flowing through each of the heaters H1 and H2 is effective. This is an area that is less than or equal to the value threshold ET (26.5 A or less).

  When the ON phase angle θ1 or OFF phase angle θ2 at the start of lighting of the heaters H1 and H2 is set within the range of the region RG3, the phase control at the start of lighting of the heater H1 and the reverse phase at the start of lighting of the heater H2 During the control, although the magnitude of the generated abnormal noise is at a level that can be heard by humans, no flickering of light occurs in the luminaire that is supplied with current from the commercial power supply 11. At least flicker is suppressed to the extent that a person does not feel flicker.

  Region RG4 is a region having a phase angle smaller than the phase angle indicated by line LN3 and a phase angle larger than the phase angle indicated by line LN1b. In the region RG4, when the phase angle in this region is set as the on phase angle θ1 or the off phase angle θ2, the effective value of the current flowing through each of the heaters H1 and H2 exceeds the effective value threshold ET, and the commercial power supply 11 This is a region where the voltage drop exceeds 7V.

  When the ON phase angle θ1 or OFF phase angle θ2 at the start of lighting of the heaters H1 and H2 is set within the range of the region RG4, the phase control at the start of lighting of the heater H1 or the reverse phase at the start of lighting of the heater H2 During the control, the magnitude of the generated abnormal noise becomes a level that can be heard by humans, and light flickers in the lighting fixture that receives the supply of current from the commercial power supply 11.

  When the ROM 22 stores a plurality of threshold values TH1, TH2, TH3, and TH4, the control unit 20 determines each of the on phase angle θ1 and the off phase angle θ2 according to the situation of the image forming apparatus 1. Is selected from a plurality of threshold values TH1, TH2, TH3, and TH4, and the on-phase angle θ1 and the off-phase angle θ2 are selected based on the resistance values of the heaters H1 and H2 and the selected threshold value. Each of these may be determined. Specifically, the threshold value may be selected by a method shown in the following (Example 1) to (Example 6).

  (Example 1) When lighting of the heaters H1 and H2 is started during printing by the image forming unit 4 and the fixing device 5, since the operation sound of the image forming unit 4 and the fixing device 5 is generated, abnormal noise is generated. Even if it occurs, the effect is small. In this case, the control unit 20 selects the threshold value TH3 (an example of the second threshold value) that suppresses only the flickering of the light of the lighting fixture, and the on-phase angle θ1 and the off-phase angle so that the phase angle is within the region RG3. Each of θ2 is determined. As a result, the amount of current flowing through the heaters H1 and H2 can be increased, and the fixing device 5 can be heated quickly.

  (Example 2) In the case where the lighting of the heaters H1 and H2 is started during the warm-up to heat the stationary fixing device 5 to a predetermined temperature, priority should be given to increasing the heating rate of the fixing device 5. It is in. In this case, the control unit 20 selects the threshold value TH3 (an example of a third threshold value) that suppresses only the flickering of the light from the lighting fixture, and the on phase angle θ1 and the off phase angle so that the phase angle is within the region RG3. Each of θ2 is determined. As a result, the amount of current flowing through the heaters H1 and H2 can be increased, and the fixing device 5 can be heated quickly.

  (Example 3) When the lighting of the heaters H1 and H2 is started in a state where the volume of sound in the vicinity of the image forming apparatus 1 acquired by the environmental sensor 25 exceeds the first level, If the magnitude is less than or equal to the first level, the influence of abnormal noise is small. In this case, the control unit 20 selects the threshold value TH2 (an example of a fourth threshold value) that suppresses only the flickering of the light of the lighting fixture, and the on phase angle θ1 and the off phase angle so that the phase angle is within the region RG2. Each of θ2 is determined. Accordingly, the amount of current flowing through the heaters H1 and H2 can be increased while suppressing the abnormal noise to an inconspicuous level, and the fixing device 5 can be heated quickly.

  (Example 4) When the lighting of the heaters H1 and H2 is started in a state where the sound volume in the vicinity of the image forming apparatus 1 acquired by the environment sensor 25 exceeds the second level that is larger than the first level. Is less affected by abnormal noise than in the case of (Example 3) above. In this case, the control unit 20 selects the threshold value TH3 (an example of a fifth threshold value) that suppresses only the flickering of the light of the lighting fixture, and the on phase angle θ1 and the off phase angle so that the phase angle is within the region RG3. Each of θ2 is determined. As a result, the amount of current flowing through the heaters H1 and H2 can be increased, and the fixing device 5 can be heated quickly.

  (Example 5) When the lighting of the heaters H1 and H2 is started in a state where the environment sensor 25 does not detect a person around the image forming apparatus 1, even if abnormal noise or light flickering of the lighting fixture occurs. The impact is small. In this case, the control unit 20 selects the threshold value TH4 (sixth threshold value), and determines each of the on phase angle θ1 and the off phase angle θ2 to be the phase angle in the region RG4. As a result, the amount of current flowing through the heaters H1 and H2 can be increased, and the fixing device 5 can be heated quickly.

  (Example 6) The control part 20 discriminate | determines the presence or absence of the fluctuation | variation of the illumination intensity detected by the illumination intensity sensor 25c, when lighting is started by the ON phase angle (theta) 1 and OFF phase angle (theta) 2 which were determined based on the effective value threshold value. When the controller 20 determines that there is no change in illuminance, each of the on-phase angle and the off-phase angle is based on another effective value threshold value that is larger than the effective value threshold value when lighting is next started. To decide. Thereby, an appropriate threshold value can be selected based on the presence or absence of actual occurrence of light flickering of the luminaire.

  After starting the lighting of the heaters H1 and H2 at the on-phase angle θ1 and the off-phase angle θ2 determined by the above-described method, the control unit 20 uses the method shown in FIG. 4 and FIG. The ratio of the time for supplying current to H1 and H2 is gradually increased, and finally the heaters H1 and H2 are completely turned on. In addition, the heater H2 with the smaller power consumption may finally be completely turned off.

  [Lighting control method according to sound suppression reference table]

  The controller 20 performs the phase control of the heater H1 and the reverse phase control of the heater H2 at different times depending on the value of the elapsed time t from when the heaters H1 and H2 are completely turned off when the heaters H1 and H2 are turned on. Also good.

  Specifically, when the elapsed time t is equal to or shorter than a predetermined time (for example, 10 seconds), the control unit 20 performs the above-described sound suppression lighting control.

  Further, when the elapsed time t exceeds a predetermined time, the control unit 20 performs lighting control according to the sound suppression reference table. The lighting control according to the sound suppression reference table is a lighting control that determines each of the on phase angle θ1 or the off phase angle θ2 in accordance with the temperature of the fixing device 5. The lighting control according to the sound suppression reference table suppresses the generation of abnormal noise and the flickering of the lighting fixture when the temperature and resistance value of the heaters H1 and H2 are sufficiently low (when the image forming apparatus 1 is on standby). It is lighting control to do.

  The sound suppression reference table is stored in the ROM 22. In the sound suppression reference table, temperatures TP1, TP2, and TP3 described later and first, second, and third phase angles described later are described.

  FIG. 9 is a diagram schematically showing lighting control according to the sound suppression reference table in one embodiment of the present invention.

  Referring to FIG. 9A, when starting lighting of heaters H1 and H2, control unit 20 sets on-phase angle θ1 at the start of lighting to the first phase angle (here, 172 °). The off phase angle θ2 is set to the second phase angle (here, 23 °). Thereafter, the control unit 20 gradually decreases the on-phase angle θ1 from the first angle and gradually increases the off-phase angle θ2 from the second angle, whereby the current supplied to each of the heaters H1 and H2 is increased. Increase gradually. As the on phase angle θ1 and the off phase angle θ2 at the start of lighting, values are set such that each of the peak currents I1p and I2p is equal to or less than the threshold value TH1.

  Referring to FIG. 9B, when the temperature TP of the fixing device 5 reaches the temperature TP1, the control unit 20 sets the off phase angle θ2 to the same value as the on phase angle θ1 at this time (here 171 °) (the ON phase angle or the OFF phase angle of the heater with the lower power consumption is matched with the ON phase angle or the OFF phase angle with the higher power consumption). Thereafter, the control unit 20 gradually decreases the on phase angle θ1 and the off phase angle θ2 while keeping the on phase angle θ1 and the off phase angle θ2 at the same value.

  Referring to FIG. 9C, when the temperature TP of the fixing device 5 reaches the temperature TP2 (> TP1), the control unit 20 sets the on phase angle θ1 and the off phase angle θ2 to be less than 90 °. The phase angle is set to 3 (here, 27 °). Thereafter, the control unit 20 maintains the on phase angle θ1 and the off phase angle θ2 at predetermined values.

  Referring to FIG. 9D, the control unit 20 turns on the heaters H1 and H2 completely when the temperature TP of the fixing device 5 reaches the temperature TP3 (> TP2). Note that the heater H2 may be completely turned off while the heater H1 is completely turned on.

  [flowchart]

  FIG. 10 is a flowchart showing the basic operation of the image forming apparatus 1 according to the embodiment of the present invention.

  Referring to FIG. 10, control unit 20 determines whether or not image forming apparatus 1 is on standby when heaters H1 and H2 are completely turned off (S1). Until it is determined that the image forming apparatus 1 is on standby, the control unit 20 repeats the process of step S1.

  When it is determined in step S1 that the image forming apparatus 1 is on standby (YES in S1). The control unit 20 determines whether or not the heaters H1 and H2 need to be turned on (S3). The controller 20 repeats the process of step S3 until it is determined that it is necessary to start the heaters H1 and H2.

  If it is determined in step S3 that the heaters H1 and H2 need to be turned on (YES in S3), the control unit 20 has an elapsed time t after the heaters H1 and H2 are completely turned off not longer than a predetermined time. Is determined (S5).

  If it is determined in step S5 that the elapsed time t is equal to or shorter than the predetermined time (YES in S5), the control unit 20 causes the control unit 20 to determine the resistance values R1 of the heaters H1 and H2 based on the elapsed time t. And R2 are calculated (S7), and each of the on-phase angle θ1 and the off-phase angle θ2 is set based on the calculated resistance values R1 and R2 (S9), and sound suppression lighting control is performed. Thereafter, the control unit 20 proceeds to the process of step S13.

  If it is determined in step S5 that the elapsed time t exceeds the predetermined time (NO in S5), the control unit 20 performs lighting control according to the sound suppression reference table (S11), and proceeds to the process of step S13.

  In step S13, the control unit 20 determines whether or not the temperature of the fixing device 5 has reached the target temperature (S13). The controller 20 repeats the process of step S13 until it is determined that the temperature of the fixing device 5 has reached the target temperature.

  If it is determined in step S13 that the temperature of the fixing device 5 has reached the target temperature (YES in S13), the control unit 20 turns off the heaters H1 and H2 (S15), and proceeds to the process of step S1.

  FIG. 11 is a flowchart showing the operation of the image forming apparatus 1 including the operation at the time of printing in the embodiment of the present invention.

  Referring to FIG. 11, in this flowchart, sound suppression lighting control is not performed during printing, and general lighting control is performed. When the heaters H1 and H2 are completely turned off, the control unit 20 determines whether a print instruction has been received (S21).

  If it is determined in step S21 that a print instruction has been received (YES in S21), the control unit 20 does not perform sound suppression lighting control, and performs lighting control during general printing (priority is given to quick heating of the fixing device 5). Lighting control) performed (S22). Subsequently, the control unit 20 determines whether or not the printing is completed (S23).

  If it is determined in step S23 that printing is not completed (NO in S23), the control unit 20 proceeds to the process of step S22.

  If it is determined in step S21 that the print instruction is not accepted (NO in S21), or if it is determined in step S23 that printing is completed (YES in S23), the control unit 20 causes the image forming apparatus 1 to be on standby. It is determined whether or not (S24).

  If it is determined in step S24 that the image forming apparatus 1 is on standby (YES in S24), the control unit 20 performs the processing after step S3 in FIG. 10 and turns off the heater in step S15 (S15). The process proceeds to step S21.

  If it is determined in step S24 that the image forming apparatus 1 is not waiting (NO in S24), the control unit 20 proceeds to the process of step S21.

  FIG. 12 is a flowchart showing the operation of the image forming apparatus 1 including the operation during warm-up according to the embodiment of the present invention.

  Referring to FIG. 12, in this flowchart, sound suppression lighting control is not performed during warm-up and printing, and general lighting control is performed. When the main switch is turned on, the control unit 20 (S31). The control unit 20 determines whether warm-up is necessary (S32). The control unit 20 repeats the process of step S32 until it is determined that warm-up is necessary.

  When it is determined in step S32 that warm-up is necessary (YES in S32), the control unit 20 does not perform sound suppression lighting control, and gives priority to general lighting control (rapid heating of the fixing device 5 is given the highest priority). Lighting control) is performed (S33). Subsequently, the control unit 20 determines whether or not the warm-up is completed (S34). The control unit 20 repeats the process of step S34 until it is determined that the warm-up has been completed.

  If it is determined in step S34 that the warm-up has been completed (YES in S34), the control unit 20 performs the processing after step S21 in FIG.

  [Effect of the embodiment]

  According to the present embodiment, since the resistance values of the heaters H1 and H2 are calculated based on the elapsed time t from the complete extinction, the currents flowing through the heaters H1 and H2 can be accurately calculated. . Further, the on-phase angle θ1 and the off-phase angle θ2 at the start of lighting are determined based on the threshold value TH1 which is a current fluctuation amount at which the magnitude of the generated abnormal noise is inaudible to humans and the calculated resistance value. Therefore, the generation of abnormal noise can be reliably suppressed.

  Further, a threshold value is selected from a plurality of threshold values according to the situation of the image forming apparatus 1, and each of the on phase angle θ1 and the off phase angle θ2 is determined based on the selected threshold value. Heating of the heaters H1 and H2 can be performed in an appropriate manner. Further, when each of the heaters H1 and H2 in the completely extinguished state is started, each of the on-phase angle θ1 and the off-phase angle θ2 is determined further based on the effective value threshold value ET. At the same time, it is possible to suppress the flickering of the lighting fixture.

  [Others]

  The image forming apparatus 1 may further include a heater other than the heaters H1 and H2.

  The controller 20 may acquire (calculate) the resistance values of the heaters H1 and H2 based on the information acquired by the temperature sensor 25d. Specifically, the ROM 22 stores a plurality of resistance value tables, and the control unit 20 selects an appropriate resistance value table based on the room temperature acquired by the temperature sensor 25d, and selects the selected resistance value. The resistance values of the heaters H1 and H2 may be obtained (calculated) using a table. Moreover, the control part 20 may correct | amend each resistance value of heater H1 and H2 based on the indoor temperature acquired with the temperature sensor 25d.

  The above-described embodiments can be appropriately combined.

  The processing in the above-described embodiment may be performed by software or by using a hardware circuit. It is also possible to provide a program for executing the processing in the above-described embodiment, and record the program on a recording medium such as a CD-ROM, flexible disk, hard disk, ROM, RAM, memory card, etc. You may decide to do it. The program is executed by a computer such as a CPU. The program may be downloaded to the apparatus via a communication line such as the Internet.

  The above-described embodiment is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Paper feed part 3 Registration roller 4 Image formation part (an example of a printing means)
5 Fixing device (an example of printing means)
6 Operation Panel 11 Commercial Power Supply 20 Control Unit (Example of Acquisition Unit and Control Unit)
21 CPU (Central Processing Unit)
22 ROM (Read Only Memory) (an example of storage means)
23 RAM (Random Access Memory)
24 Temperature detection unit 25 Environmental sensor 25a Sound sensor 25b Human sensor 25c Illuminance sensor 25d Temperature sensor 30a, 30b Switch unit 31 Line filter 32 Secondary power supply 33 Zero cross detection circuit 34 Choke coil 34a Core 34b Winding H1, H2 Heater ( Example of first and second heaters)
M Print medium REM1, REM2 Heater remote signal SB1 Main board SB2 Low voltage power supply board ST Secondary transfer area TR Transport path

Claims (15)

Each of the first and second heaters having different power consumption;
Storage means for storing a first threshold relating to the amount of variation in current;
Obtaining means for obtaining respective resistance values of the first and second heaters based on an elapsed time from the complete extinction of each of the first and second heaters;
A phase in which the current supplied to the first heater is controlled by the phase control that adjusts the ON phase angle, which is the phase angle at which the supply of the alternating current from the power supply is started, and the supply of the alternating current from the power supply is stopped. Control means for controlling the current supplied to the second heater by anti-phase control for adjusting the off-phase angle, which is an angle,
The control means, when starting lighting of each of the first and second heaters in a completely extinguished state, each resistance value of the first and second heaters acquired by the acquisition means, First control means for determining each of the on phase angle and the off phase angle based on the first threshold;
The first threshold value is a magnitude of abnormal noise generated due to a fluctuation in current flowing through the first heater at the on-phase angle, and a fluctuation in current flowing through the second heater at the off-phase angle. An image forming apparatus in which the magnitude of abnormal noise generated due to the current is the amount of fluctuation in current at a level that cannot be heard by humans.   The first control means is configured to detect a magnitude of an abnormal noise generated due to a variation in a current flowing through the first heater at the on phase angle, and a current flowing through the second heater at the off phase angle. 2. The image forming apparatus according to claim 1, wherein values for which the magnitudes of abnormal sounds generated due to fluctuations both fall within a predetermined range are determined as the on phase angle and the off phase angle.   The image forming apparatus according to claim 1, wherein power consumption of the first heater is larger than power consumption of the second heater. The storage means stores a plurality of threshold values relating to a variation amount of current, the threshold value including the first threshold value,
The first control means includes
A selection unit that selects a threshold value from the plurality of threshold values according to the state of the image forming apparatus;
Determination means for determining each of the on phase angle and the off phase angle based on the resistance value of each of the first and second heaters acquired by the acquisition means and the threshold value selected by the selection means. The image forming apparatus according to claim 1, comprising: A printing unit that prints on the print medium;
5. The image formation according to claim 4, wherein the selection unit selects a second threshold value larger than the first threshold value among the plurality of threshold values when the lighting is started during printing by the printing unit. apparatus. A fixing device heated by the first and second heaters;
The selection unit selects a third threshold value larger than the first threshold value among the plurality of threshold values when starting the lighting during the warm-up to heat the fixing device in a resting state to a predetermined temperature. The image forming apparatus according to claim 4 or 5. A sound sensor for acquiring sound near the image forming apparatus;
When the lighting starts in a state where the volume of the sound acquired by the sound sensor exceeds the first level, the selection unit has a first value greater than the first threshold value among the plurality of threshold values. The image forming apparatus according to claim 4, wherein a threshold value of 4 is selected.   The selection means, when starting the lighting in a state in which the volume of sound acquired by the sound sensor exceeds a second level that is larger than the first level, The image forming apparatus according to claim 7, wherein a fifth threshold value greater than the fourth threshold value is selected. A human sensor for detecting a person around the image forming apparatus;
The said selection means selects the 6th threshold value larger than the said 1st threshold value among these threshold values, when the said lighting is started in the state which does not detect a human with the said human sensitive sensor. The image forming apparatus according to any one of 8 to 8. The storage means further stores an effective value threshold value which is a threshold value of an effective value of a current flowing while each of the first and second heaters is on,
The effective value threshold is a value in which a voltage drop amount of the power source generated due to currents flowing through the first and second heaters is within a predetermined range,
When the first control unit starts lighting each of the first and second heaters in a completely extinguished state, each of the on-phase angle and the off-phase angle is further based on the effective value threshold value. The image forming apparatus according to claim 1, wherein: An illuminance sensor for detecting the illuminance of the environment in which the image forming apparatus is installed;
Discriminating means for discriminating whether or not there is a change in illuminance detected by the illuminance sensor when the lighting is started at the on phase angle and the off phase angle determined based on the effective value threshold;
In the case where the determination unit determines that there is no change in illuminance detected by the illuminance sensor, the next time lighting is started, based on another effective value threshold value that is larger than the effective value threshold value, The image forming apparatus according to claim 10, further comprising redetermination means for determining each of the on phase angle and the off phase angle. A temperature sensor that acquires temperature information in a room in which the image forming apparatus is installed;
The image forming apparatus according to claim 1, wherein the acquisition unit acquires the resistance value of each of the first and second heaters based further on information acquired by the temperature sensor.   The first control means includes the on-phase angle so that the ratio of the time for supplying current to each of the first and second heaters gradually increases with the passage of time from the start of lighting. The image forming apparatus according to claim 1, wherein each of the first phase angle and the off phase angle is determined. The control means includes
When starting lighting of each of the first and second heaters in a completely extinguished state, the on phase angle and the off phase depend on the temperature of the fixing device heated by the first and second heaters. Second control means for determining each of the corners;
If the elapsed time from the complete extinction of the first and second heaters is less than or equal to a predetermined time at the start of lighting of the first and second heaters, select the control by the first control means, Control selection for selecting control by the second control means when the first and second heaters start to turn on and the elapsed time from the complete turn-off of the first and second heaters exceeds a predetermined time Further comprising means,
The second control means is supplied to each of the first and second heaters from the start of lighting of the first and second heaters until the temperature of the fixing device reaches the first temperature. Gradually increase the current
The second control unit includes the on-phase angle and the off-phase angle from when the temperature of the fixing device reaches the first temperature until it reaches the second temperature higher than the first temperature. With the same value, gradually decreasing the on phase angle and the off phase angle,
The second control means includes the on-phase angle and the off-phase angle from when the temperature of the fixing device reaches the second temperature until reaching the third temperature higher than the second temperature. The image forming apparatus according to claim 13, wherein a predetermined phase angle is maintained. A control method for an image forming apparatus, comprising: first and second heaters having different power consumptions; and storage means for storing a first threshold value relating to a current fluctuation amount.
Obtaining the resistance values of each of the first and second heaters based on the elapsed time from the complete extinction of each of the first and second heaters;
A phase in which the current supplied to the first heater is controlled by the phase control that adjusts the ON phase angle, which is the phase angle at which the supply of the alternating current from the power supply is started, and the supply of the alternating current from the power supply is stopped. A control step of controlling a current supplied to the second heater by an anti-phase control that adjusts an off-phase angle that is an angle, and
In the control step, when starting the lighting of each of the first and second heaters in a completely extinguished state, the resistance values of the first and second heaters acquired in the acquisition step, A first control step of determining each of the on phase angle and the off phase angle based on the first threshold;
The first threshold value is a magnitude of abnormal noise generated due to a fluctuation in current flowing through the first heater at the on-phase angle, and a fluctuation in current flowing through the second heater at the off-phase angle. The control method for the image forming apparatus, wherein the magnitude of the abnormal noise caused by the current is the amount of fluctuation of the current at a level that cannot be heard by humans.

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