JP2006351400A - Heater control device, image forming device, heater control method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heater control device which can suppress outbreak of a flicker surely and occurrence of harmonics and a beat sound of a coil. <P>SOLUTION: This is the heater control device 20 in which electric current supplied to the heater 25 is turned on and off with a micro period T, and this has a heater control part 22 in which phase control is carried out so that heater current is gradually increased at the time of turning on of heater current in micro period and which controls so that a time to carry out phase control in the first micro period in heating period after moving from a non-heating period to the heating period and a time to carry out phase control in the micro period of second time or later in the heating period may become different. For that reason, rush current can be suppressed sufficiently and the occurrence of the harmonics and the beat sound of the coil can be suppressed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heater control device for a fixing device mounted on a copying machine, a printer, or the like. In particular, the present invention relates to a technique for controlling a fixing device using a thin fixing roll having a small heat capacity.

  In order to keep the fixing roll surface temperature of the fixing device constant, conventionally, heater control for turning on / off the power to the heater (hereinafter referred to as on / off control) has been performed. This is because the surface temperature of the fixing roll is periodically detected by a thermistor, and when the detected temperature falls below the lower limit value of the target temperature as shown in FIG. If it exceeds the upper limit, the energization is stopped to keep the surface temperature of the fixing roll constant.

  In recent years, thin fixing rolls having a small heat capacity have been used. A thin fixing roll having a small heat capacity can quickly reach the target temperature, so that the warm-up time can be shortened. However, since the thin fixing roll has a large temperature change with respect to the energization time, problems such as occurrence of temperature overshoot and a large temperature difference in the roll axis direction occur. Therefore, during the heating period in which the surface temperature of the fixing roll reaches the upper limit value from the lower limit value of the target temperature, power is forcibly supplied with a very short cycle (corresponding to the micro cycle of the present invention, hereinafter referred to as a cutoff cycle). Cut-off control is used to turn on and off. As shown in FIG. 1B, within the cut-off period T, the heater current is continuously turned on and off.

  The cut-off period T is generally 1 second or less, and by changing the setting of the cut-off period and the on-period Ton within the period, various power supply and finer power supply are possible. Thereby, the overshoot of the fixing roll temperature and the temperature difference in the roll axis direction can be reduced.

  Incidentally, a halogen lamp is generally used as a heat source of the fixing device. Since this halogen lamp has a positive resistance characteristic to temperature, a large inrush current flows when the filament temperature is low. For example, as shown in FIGS. 1A and 1B, a large inrush current is generated by energizing the first heater that has shifted from the non-heating period to the heating period. The inrush current causes voltage fluctuations in a power supply line to which a device equipped with a fixing device is connected, and flickers, for example, in an indoor fluorescent lamp.

  As a general control method for suppressing an inrush current, a soft start in which a current supplied to the heater (hereinafter referred to as a heater current) is gradually increased when energization of the heater is started (for example, Patent Documents). 1-3). FIG. 2A shows a waveform of the heater current when the soft start is not performed, and FIG. 2B shows a waveform of the heater current due to the soft start. As shown in FIG. 2A, during the heater-on period, the current to be energized is not maximized at once, but the amount of current to be energized gradually is increased as shown in FIG. By limiting the amount of current at the beginning of the heating period in which the inrush current tends to flow, and gradually increasing the amount of current, the occurrence of the inrush current can be prevented.

Japanese Patent Laid-Open No. 11-24487 JP-A-10-91037 JP-A-10-133504

  As a countermeasure against flicker in cut-off control, a method of combining soft start with cut-off control as shown in FIG. In this case, when the heater is turned on, the soft start by the phase control is performed only for a small predetermined period which is sufficiently smaller than the cycle of the cutoff control. In the ON period Ton of the cutoff control, the phase control is performed only for the first time tp. This phase control is performed for the same time tp in all ON periods Ton. That is, the phase control times are all set at the same tp.

The above-described control is a method for suppressing flicker by repeatedly performing phase control for the same period each time the heater is turned on for a heater that is repeatedly turned on and off in a very short cycle such as cut-off control. The following problems occur.
First, since the total time during which the phase control is performed becomes longer, the time average value of the harmonic current becomes larger. Since the AC waveform is greatly distorted by the phase control, harmonic current is likely to be generated. The generated harmonic current causes malfunction of peripheral devices and the power supply system.

  If the execution time of the phase control is set to be short in order to suppress the time average value of the harmonic current, the phase control is conventionally performed for the same time tp in all the on periods Ton. The first inrush current when shifting to the heating period cannot be sufficiently suppressed. As a result, flicker deteriorates.

  On the other hand, when the on-time of phase control is set such that harmonic current and flicker do not become a problem, a roaring noise of a noise countermeasure coil provided in the device is likely to occur. Since the cut-off control is repeatedly turned on and off in a short time, a coiling sound can be heard in synchronization with the turn-on and turn-off timing, which can be very disturbing depending on the setting environment.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heater control device that can reliably suppress the generation of flicker and can also suppress the generation of harmonics and beat noise of a coil. .

  In order to achieve such an object, the heater control device of the present invention has a heating period and a non-heating period, and during this heating period, the heater current supplied to the heater is turned on at a minute cycle shorter than the heating period. A heater control device for turning off, wherein when the heater current is turned on within the minute period, phase control is performed to gradually increase the heater current, and the transition from the non-heating period to the heating period is performed. Control means for controlling so that the time for performing the phase control in the first micro-cycle and the time for performing the phase control in the second and subsequent micro-cycles within the heating period are different. As described above, according to the present invention, the time for performing the phase control in the first minute cycle and the time for performing the phase control in the second and subsequent minute cycles are controlled to be different. For this reason, for example, in the first minute cycle in which a large inrush current may occur, the inrush current can be sufficiently suppressed by setting the phase control time longer. In addition, in the second and subsequent micro cycles in which the influence of the inrush current is reduced, the generation of harmonics and coiling noise can be suppressed by setting the phase control time short.

  In the heater control device having the above-described configuration, the control unit may control the time for performing the phase control in the second and subsequent micro cycles to be shorter than the time for performing the phase control in the first micro cycle. . Therefore, in the first minute period in which a large inrush current may occur, the inrush current can be sufficiently suppressed by setting the phase control time longer. In addition, in the second and subsequent micro cycles in which the influence of the inrush current is reduced, the generation of harmonics and coiling noise can be suppressed by setting the phase control time short.

  In the heater control device having the above-described configuration, the control unit may control the time for performing the phase control to be zero in the second and subsequent minute cycles. Therefore, it is possible to sufficiently suppress harmonics and coil beat noise.

  In the heater control device having the above-described configuration, the control unit may control the length of the first minute cycle to be different from the length of the second and subsequent minute cycles. For example, by setting the first minute period to be longer than the second minute and subsequent minute periods, it is possible to take a sufficient amount of time for phase control. Therefore, it is possible to sufficiently suppress the inrush current that is generated most greatly in the first minute cycle, and to prevent the occurrence of flicker.

  In the heater control device having the above-described configuration, the control unit may control the second and subsequent minute cycles to be shorter than the first minute cycle. Therefore, it is possible to sufficiently suppress the inrush current that is generated most greatly in the first minute cycle, and to prevent the occurrence of flicker.

  In the heater control device having the above-described configuration, the control unit includes a time for performing the phase control in the first minute cycle within the heating period, and a time for performing the phase control in the second and subsequent minute cycles within the heating period. May be controlled differently for each of the plurality of heaters. Since the rated power varies depending on the heater, the magnitude of the generated inrush current also varies. Therefore, by changing the time for performing the phase control according to the heater, the inrush current can be sufficiently suppressed, and the occurrence of flicker can be prevented.

  In the heater control device having the above-described configuration, when the control unit determines that there is little variation in the combined current supplied to the plurality of heaters when the plurality of heaters are exclusively operated, the second and subsequent heating periods are performed. It is preferable to set the time for performing the phase control to zero in the minute period. Since an inrush current is unlikely to occur when the fluctuation of the combined current is sufficiently small, unnecessary control can be stopped.

  The image forming apparatus of the present invention has a configuration in which the fixing member of the fixing device is heated by the heater control device according to any one of claims 1 to 7 during standby of a job. When the image forming apparatus is in a standby state where the influence of the humming noise of the harsh coil is large, it is possible to sufficiently suppress the humming noise of the coil.

  The heater control method of the present invention is a heater control method in which a heater current supplied to a heater is turned on / off in a heating cycle with a minute cycle shorter than the heating period, and is changed from a non-heating period to the heating period. When the transition is detected, in the first minute cycle within the heating period, a step of executing phase control for gradually increasing the heater current at a first time, and in the second and subsequent minute cycles within the heating period And performing the phase control at a second time set shorter than the first time. As described above, according to the present invention, the time for performing the phase control in the first minute cycle is controlled so as to differ from the time for performing the phase control in the second and subsequent minute cycles. For this reason, for example, in the first minute cycle in which a large inrush current may occur, the inrush current can be sufficiently suppressed by setting the phase control time longer. In addition, in the second and subsequent micro cycles in which the influence of the inrush current is reduced, the generation of harmonics and coiling noise can be suppressed by setting the phase control time short.

  The heater control program of the present invention is a heater control program for turning on and off a heater current supplied to a heater in a heating cycle with a minute cycle shorter than the heating period, and from the non-heating period to the heating period. When the transition is detected, in the first minute cycle within the heating period, the phase control for gradually increasing the heater current in the first time is performed, and in the minute cycle after the second time in the heating period. And performing the phase control at a second time set shorter than the first time. As described above, according to the present invention, the time for performing the phase control in the first minute cycle is controlled so as to differ from the time for performing the phase control in the second and subsequent minute cycles. For this reason, for example, in the first minute cycle in which a large inrush current may occur, the inrush current can be sufficiently suppressed by setting the phase control time longer. In addition, in the second and subsequent micro cycles in which the influence of the inrush current is reduced, the generation of harmonics and coiling noise can be suppressed by setting the phase control time short.

  According to the present invention, generation of flicker can be reliably suppressed, and generation of harmonics and coiling noise can be suppressed.

  Preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  First, the configuration of an image forming apparatus equipped with a fixing device will be described with reference to FIG. In response to a predetermined print start signal, image data output from an image processing unit (not shown) is converted into an optical signal by a laser exposure device (hereinafter referred to as ROS) 2 and irradiated to the photosensitive drum 4 rotating in the direction of the arrow. . The surface of the photosensitive drum 4 is uniformly charged to, for example, −700 V by the charger 3, and an electrostatic latent image is formed on the surface by receiving light irradiation from the ROS 2.

  The electrostatic latent image is attenuated to, for example, about −200 V at the maximum density portion. At this time, when the laser exposure amount is changed, the potential of the electrostatic latent image is changed, and the finally obtained image density is changed. With the rotation of the photosensitive drum 4, the electrostatic latent image is visualized as a toner image by the developing device 5. The developing device 5 is filled with toner and a carrier for charging and transporting the toner, and the image density finally obtained is changed by changing the mixing ratio.

  A developing bias voltage is applied to the developing roll 6 that transports toner and carrier to the surface of the photosensitive drum 4, and the toner is developed by a potential difference (developing contrast potential) created between the electrostatic latent image and the developing bias voltage. 6 to the surface of the photosensitive drum 4, and a toner image is formed on the surface of the photosensitive drum 4. At this time, when the developing bias is changed, the developing contrast potential changes, and the finally obtained image density changes.

  The charge of the toner image formed on the surface of the photosensitive drum 4 by the developing device 5 is adjusted by a transfer auxiliary charger (not shown) and reaches the transfer device 7. On the other hand, the transfer belt 9 is stretched by a drive roll and a follower roll and circulates in the direction of the arrow to form a transfer portion between the transfer drum 9 and the photosensitive drum 4.

  In response to the image recording instruction, the paper feeding unit selects one of the plurality of paper trays and transports the paper on which the image is to be recorded to the transfer unit via the paper transport path. The toner image on the photosensitive drum 4 is transferred to the sheet conveyed to the transfer unit. At this time, a voltage having a polarity opposite to that of the toner passing through the transfer roll 8 is applied to the transfer belt 9. Thereafter, the sheet is further conveyed to the fixing device 12 via the sheet conveying path, where the toner is permanently fixed to the sheet by heat and pressure. The paper on which the toner is fixed on the paper and the image is formed is discharged from the discharge roll to the outside of the image forming apparatus via the paper conveyance path.

  Next, the configuration of the heater control device 20 that receives power supply and controls the heater on / off will be described. As shown in FIG. 5, the heater control device 20 detects a heater 25 that receives heat from the AC power supply 30 and generates heat, a roll temperature detection unit 26 that measures the surface temperature of the fixing roll 24, and a zero cross point of the AC power supply. And a heater control unit 22 that calculates the energization time of the heater current supplied to the heater 25 and controls the on / off switching unit 23 on and off according to the calculated energization time. The fixing roll 24 is a thin one having a small heat capacity. The heater control unit 22 includes a CPU as a central processing unit that executes various arithmetic processes, a ROM that stores control programs, a RAM that stores various data, an input / output circuit (I / O), and a bus line that connects them. It is configured as a logical operation circuit consisting of The CPU performs arithmetic processing according to a program read from the ROM, thereby realizing heater control processing described later.

  The zero cross detection unit 21 detects the timing at which the voltage 0V (zero cross point) passes when the AC power from the AC power source 30 shifts to the + component and the − component, and outputs this to the heater control unit 22 as a zero cross signal. To do.

  The heater control unit 22 performs phase control of the current supplied to the heater 25 based on the zero cross point detected by the zero cross detection unit 21. Generally, when the time from the zero cross point to the heater ON is set long, the energization time to the heater 25 is shortened. This suppresses the inrush current immediately after the image forming apparatus is turned on. Conversely, if the time from the zero cross point to the heater on is short, the energization time to the heater 25 becomes long. Further, the heater control unit 22 performs cut-off control for forcibly turning on and off the energization with a very short cut-off period T. In addition, phase control for gradually increasing the heater current is performed at the beginning of the energization period in which the heater current is supplied to the heater 25.

  In the present embodiment, when shifting from the non-heating period to the heating period, the phase control period (tp1 shown in FIG. 6) in the ON period Ton of the first cutoff control (hereinafter referred to as the ON period Ton for simplicity). , Which corresponds to the first time of the present invention) and the phase control period (which is tp2 shown in FIG. 6 and corresponds to the second time of the present invention) in the second and subsequent ON periods Ton. Each can be set separately. The phase control period tp1 in the first on-period Ton is set to be long so that the inrush current can be suppressed. The phase control period tp2 in the second and subsequent on periods Ton is set to be short so that harmonics and abnormal noise of the coil can be suppressed.

  In the first on-period Ton from the non-heating period to the heating period, since the influence of the inrush current is very large, the inrush current can be suppressed by taking a longer phase control time. Further, in the second and subsequent ON periods Ton, the heater is also warmed by the first energization, and it is not necessary to consider the effect of the inrush current as much as the first time, so the phase control time is shortened. Thereby, the total time during which the phase control is performed can be shortened, and the time average value of the harmonic current can be reduced. Furthermore, it is possible to suppress abnormal noise generated in the noise countermeasure coil.

  The operation procedure of the heater control device 20 will be described with reference to the flowchart shown in FIG. When the heater temperature detecting unit 26 detects that the surface temperature of the fixing roll 24 has become equal to or lower than the lower limit value of the target value, the heater control device 20 resumes energization to the heater 25. First, the heater control device 20 determines whether or not the number of times the heater 25 is turned on is the first time after shifting to the heating period. When the heater is turned on for the first time (step S1 / YES), the cut-off control is turned on at Ton and the phase control period at tp1.

  Further, when the heater is turned on for the second time and after instead of the heater being turned on for the first time (step S1 / NO), energization is performed with the on period of the cutoff control being Ton and the phase control period being tp2 (step S3). As shown in FIG. 6, the first phase control period tp1 is set longer than the second and subsequent phase control periods tp2.

  When the on-period Ton of the cut-off control elapses, this time, the off-period Toff is entered, and the energization to the heater 25 is forcibly turned off (step S4). This procedure is repeated, and when it is detected that the surface temperature of the fixing roll 24 is equal to or higher than the upper limit value of the target temperature (step S5 / YES), the heater temperature control is terminated.

As described above, in this embodiment, when the number of times the heater 25 is turned on is the first time after the transition to the heating period, generation of inrush current can be suppressed by performing the phase control longer. . In addition, when the heater 25 is turned on for the second time or later, the generation of harmonics and beat noise can be suppressed by performing phase control shortly.
[Modification of Example 1]

  Further, as a modification of the first embodiment, as shown in FIG. 8, when the number of times the heater 25 is turned on becomes 2 times or more, it is possible not to perform the soft start by the phase control. How to hear the noise noise of the coil for noise reduction varies depending on the installation environment and the person, and even if the phase control period is set short, an unpleasant sensation cannot be completely eliminated. Therefore, the phase control may be set not to be performed when the number of heaters turned on in the heating period T is two or more. In the second and subsequent ON periods Ton, the heater 25 is also warmed by the first energization, and the inrush current is not as great as the first. Therefore, by setting so as not to perform the phase control, flicker is slightly worsened, but the beat sound of the coil can be completely shut down.

  A second embodiment of the present invention will be described with reference to the accompanying drawings. The configuration of the present embodiment is the same as the configuration of the first embodiment described above, and the description thereof is omitted. In this embodiment, as shown in FIG. 10, the non-heating period is changed to the heating period, and the cut-off period of the first cut-off control is set longer than the cut-off period of the second transfer.

  When it is desired to perform the cut-off control with a shorter period or when the heater power is large, if the inrush current is sufficiently suppressed, the phase control time tp1 becomes longer than the on-time period Ton of the cut-off control. There is a case. FIG. 9 shows a case where the phase control is also stopped at the end of the on-period Ton of the cutoff control. In this example, the phase control of the first cut-off control cannot take a sufficient time to suppress the inrush current. Therefore, the inrush current is generated in the second on-period Ton.

  On the other hand, in this embodiment, as shown in FIG. 10, the cycle T ′ of the first cut-off control is set to be longer than the cycle T of the second transition. The cut-off control cycle is set to be long only in the first cut-off control that has shifted from the non-heating period to the heating period, and the second and subsequent cut-off control is performed in the conventional cycle. Therefore, in the first cutoff control, the inrush current can be sufficiently suppressed by taking a sufficient phase control time. Furthermore, conventional fine power control is possible, and the temperature overshoot and the temperature distribution in the roll axis direction, which are the original purposes of cut-off control, can be improved. In the second and subsequent cut-off control, the cut-off control can be performed in the same manner as in the prior art or in a shorter cycle. Thereby, the total time during which the phase control is performed can be shortened, and the time average value of the harmonic current can be reduced. Furthermore, it is possible to suppress abnormal noise generated in the noise countermeasure coil.

The operation procedure of this embodiment will be described with reference to the flowchart shown in FIG.
When the heater temperature detecting unit 26 detects that the surface temperature of the fixing roll 24 has become equal to or lower than the lower limit value of the target value, the heater control device 20 resumes energization to the heater 25. First, the heater control device 20 determines whether or not the number of times the heater 25 is turned on is the first time after shifting to the heating period. When the heater is turned on for the first time (step S10 / YES), the cut-off control is turned on at Ton ′ and the phase control period at tp1 (step S11). After that, the current supply to the heater 25 is forcibly stopped for the cut-off control off time Toff (step S12).

  Further, when the heater is turned on for the second and subsequent times instead of the heater being turned on for the first time (step S10 / NO), the on-time of the cutoff control is set to Ton and the phase control period is set to tp2 (step S13). After that, the current supply to the heater 25 is forcibly stopped for the cut-off control off time Toff (step S14). As shown in FIG. 10, the on period Ton ′ of the first cutoff control is set longer than the on period Ton of the second and subsequent cutoff controls. By taking a sufficiently long ON period Ton 'of the first cut-off control, the inrush current can be sufficiently suppressed even when the heater power is large.

  This procedure is repeated, and when it is detected that the surface temperature of the fixing roll 24 is equal to or higher than the upper limit value of the target temperature (step S15 / YES), the heater temperature control is terminated (step S5).

  The present embodiment will be described in detail with reference to the accompanying drawings. The configuration of the present embodiment is the same as the configuration of the first embodiment described above, and the description thereof is omitted. In this embodiment, as shown in FIG. 12, a plurality of heaters (hereinafter referred to as a main heater 41 and a sub heater 42) are provided, and the fixing roll 40 is heated by these. The main heater 41 and the sub heater 42 are different in rated power.

  Usually, in a fixing device of a copying machine or a printer, a plurality of heaters having different rated powers are used. Since the magnitude of the inrush current varies depending on the value of the rated power, the optimum value of the phase control period also varies as a result. Therefore, in the present embodiment, the phase control period can be set individually for the first and second and subsequent cut-off control in each of the main heater 41 and the sub heater 42. That is, the first phase control period tp1 of the cutoff control to the main heater 41, the second and subsequent phase control periods tp2, the first phase control period tp3 of the cutoff control to the sub heater 42, and the second and subsequent times. The phase control period tp4 is set individually. In particular, in the present embodiment, as shown in FIG. 13, it is set so that tp1 ≧ tp3 ≧ tp2 ≧ tp4.

Since the phase control period can be set in accordance with the rated power of the heater in this way, flicker can be suppressed regardless of the rated power of the heater, and harmonics and coil beat noise are optimally suppressed. be able to.
[Modification of Example 3]

  As a modification of the third embodiment described above, there is a case where the main heater 41 and the sub heater 42 are operated exclusively. Flicker is caused by fluctuations in the current flowing from the commercial power source to the device main body via the outlet, that is, the combined current of the current supplied to the main heater 41 and the sub heater 42. As shown in FIG. 15A, when there is a period in which both the main heater 41 and the sub heater 42 are on, the amount of fluctuation of the combined current is large. On the other hand, when the main heater 41 and the sub heater 42 are operated exclusively as in the present embodiment, the amount of fluctuation of the combined current becomes a small value as shown in FIG. Therefore, in this embodiment, control is performed so that the phase control period becomes zero (tp4 = 0 shown in FIG. 14) in the second and subsequent phase control of the cutoff control. In the second and subsequent cut-off control, since the fluctuation amount of the combined current is small, it is less likely to be affected by flicker even if the phase control period is zero.

  In addition, the heater control devices according to the first to third embodiments described above can obtain a remarkable effect particularly when waiting for a job such as printing. An image forming apparatus such as a copying machine or a printer has a larger inrush current during standby than during image formation. Furthermore, abnormal coil noise caused by phase control becomes more conspicuous during standby than during image formation that is drowned out by the operation sound of the device. Therefore, a remarkable effect can be obtained by performing the heater control device shown in the first to third embodiments during standby.

  The embodiment described above is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

(A) shows the heater current during normal on / off control, and (B) shows the heater current during cut-off control. (A) shows the heater current during normal on / off control, and (B) is a diagram showing the heater current when phase control by soft start is performed. It is a figure which shows the heater electric current which flows in the control which combined the soft start by cut-off control and phase control. 1 is a diagram illustrating a configuration of an image forming apparatus. It is a figure which shows the structure of a heater control apparatus. It is a figure which shows the heater electric current which flows into a heater by control of the heater control apparatus of Example 1. FIG. It is a flowchart which shows the operation | movement procedure of the heater control apparatus of Example 1. FIG. It is a figure which shows the heater electric current which flows into a heater by control of the heater control apparatus of the modification of Example 1. FIG. It is a figure for demonstrating the subject which arises when the electric power of a heater is large. It is a figure which shows the heater electric current which flows into a heater by control of the heater control apparatus of Example 2. FIG. It is a flowchart which shows the operation | movement procedure of the heater control apparatus of Example 2. It is a block diagram which shows the structure of the heater control apparatus of Example 3. FIG. It is a figure which shows the heater current which flows into a heater by control of the heater control apparatus of Example 3. FIG. It is a figure which shows the heater electric current which flows into a heater by control of the heater control apparatus of the modification of Example 3. FIG. It is a figure which shows the heater electric current which flows into a main heater and a sub heater, and the synthetic | combination electric current which synthesize | combined these.

Explanation of symbols

1 Image forming apparatus 2 ROS
DESCRIPTION OF SYMBOLS 3 Charger 4 Photoconductor 5 Developing device 6 Developing roll 7 Transfer device 8 Transfer roll 9 Transfer belt 10 Cleaner 11 Charger 12 Fixing device 20 Heater control device 21 Zero cross detection unit 22 Heater control unit 23 On / off switching unit 24 Fixing roll 25 Heater 26 Roll temperature detector 30 AC power supply

Claims (10)

A heater control device having a heating period and a non-heating period, wherein in the heating period, the heater current supplied to the heater is turned on and off in a minute cycle having a cycle shorter than the heating period,
When the heater current is turned on within the minute period, phase control for gradually increasing the heater current is performed,
Time to shift from the non-heating period to the heating period, the time for performing the phase control in the first minute period in the heating period, and the time for performing the phase control in the second and subsequent minute periods in the heating period A heater control device having control means for controlling the difference between the heater control unit and the heater control unit.   2. The control unit according to claim 1, wherein the time for performing the phase control in the second and subsequent micro cycles is shorter than the time for performing the phase control in the first micro cycle. Heater control device.   2. The heater control device according to claim 1, wherein the control unit controls the time for performing the phase control to be zero in the second and subsequent minute cycles.   2. The heater control device according to claim 1, wherein the control unit performs control so that a length of the first minute cycle is different from a length of the second and subsequent minute cycles.   5. The heater control device according to claim 4, wherein the control unit controls the second and subsequent micro cycles to be shorter than the first micro cycle.   The control means is configured such that the time for performing the phase control in the first minute cycle in the heating period and the time for performing the phase control in the second and subsequent minute cycles in the heating period are different for each of the plurality of heaters. The heater control apparatus according to claim 1, wherein the control is performed as follows.   When the control means determines that there is little variation in the combined current supplied to the plurality of heaters when operating the plurality of heaters exclusively, the control unit performs the phase control in a minute cycle after the second heating period. 7. The heater control apparatus according to claim 6, wherein a time for performing the setting is set to zero.   An image forming apparatus, wherein a fixing member of a fixing device is heated by a heater control device according to claim 1 during standby of a job. In the heating period, a heater control method for turning on and off the heater current supplied to the heater with a minute period shorter than the heating period,
Detecting a transition from a non-heating period to the heating period, performing phase control for gradually increasing the heater current in a first time in the first minute period in the heating period;
And a step of performing the phase control at a second time set shorter than the first time in the second and subsequent minute cycles within the heating period. In the heating period, a heater control program for turning on and off the heater current supplied to the heater at a minute cycle shorter than the heating period,
Detecting a transition from a non-heating period to the heating period, performing phase control for gradually increasing the heater current in a first time in the first minute period in the heating period;
And a step of performing the phase control at a second time set shorter than the first time in the second and subsequent minute cycles within the heating period.

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