JP2021148988A - Heater control device, heater control method, and image forming apparatus - Google Patents

Abstract

To provide a heater control device that allows prevention of a harmonic current without deteriorating electric power responsiveness.SOLUTION: A heater control device has control means that switches and uses a first lighting pattern and a second lighting pattern to achieve a predetermined lighting duty ratio for every control period that is the integral multiple of the period of the AC voltage through phase control of controlling the phase angle of an AC voltage carried on a heater, so as to control the lighting of the heater. The second lighting pattern has a smaller number of half wave sections in which the phase control for every control period is performed, and a smaller number of half wave sections in which the symmetry between the plus side and the minus side of the AC voltage is maintained through the phase control, than the first lighting pattern.SELECTED DRAWING: Figure 2

Description

The present invention relates to a heater control device, a heater control method, and an image forming device.

In an image forming apparatus that heats and fixes a toner image transferred to a recording member such as paper by a fixing unit, the temperature of the fixing unit is appropriately controlled in consideration of user convenience and energy efficiency. The fixing unit is equipped with a heating roller having a built-in heater such as a halogen heater, a temperature sensor for detecting the surface temperature of the heating roller, and the heater control device controls the lighting of the heater based on the surface temperature of the heater and the target temperature. To control the temperature of the fixing unit to the set temperature.

As a control method, the energization rate is set for each half cycle (half wave section) of the AC voltage from the AC power supply, and the energization is set so that the predetermined average energization rate is obtained for each control cycle that is an integral multiple of the AC voltage cycle. A control method for controlling lighting (energization control) of a heater by a pattern is known (for example, Patent Document 1). Here, the energization rate is the ratio of the time for energizing the heater to the half cycle (half wave section) of the AC voltage, and is based on the phase control that controls the phase angle of energization according to the on / off timing of the AC voltage. Can be changed. The "average energization rate" and "energization pattern" may also be referred to as "lighting duty ratio" and "lighting pattern", respectively. Hereinafter, in the present specification, the "average energization rate" and "energization pattern" will be referred to as "lighting duty ratio" and "lighting pattern".

By the way, the fixing unit is equipped with a large heater in order to shorten the time required for the surface temperature to rise to the set temperature due to the demand for shortening the printing time. Since a large heater consumes a large amount of power, an inrush current is generated at the initial stage of temperature control when the heater is energized. In particular, since the halogen heater has a small resistance value when the temperature is low, the inrush current tends to be larger in the initial stage of temperature control when the temperature is low. Due to the generation of this inrush current, the AC voltage of the power supply drops, causing flicker (appearing as flicker of the fluorescent lamp) in the fluorescent lamp or the like that shares the fixing unit and the power supply system.

When phase control is performed, the inrush current can be reduced by lowering the lighting duty ratio when the heater is started up, and the occurrence of flicker due to voltage fluctuation can be suppressed. However, by performing phase control, the AC voltage waveform supplied to the heater is greatly distorted, so that a harmonic current is likely to be generated. Harmonic currents cause malfunctions in peripheral devices and power supply systems.

In order to suppress this harmonic current, in the fixing device described in Patent Document 1, a plurality of lighting patterns having different combinations of energization rates in the half-wave section are prepared for each of the plurality of different lighting duty ratios. Then, when deciding the lighting pattern to be newly used, the average value of the harmonic current generated by the newly used lighting pattern and the harmonic current generated by the lighting pattern used in the past predetermined period is calculated for each lighting pattern. calculate. Further, one of the lighting patterns having the lighting duty ratio corresponding to the required power is selected from the lighting patterns in which the calculated average value does not exceed the standard value of the average harmonic current. Further, if any lighting pattern having a lighting duty ratio corresponding to the required power exceeds the regulation value of the harmonic current, the lighting duty ratio is lowered to select the lighting pattern.

However, in the heater control device described in Patent Document 1, since the harmonic current cannot be suppressed while maintaining the lighting duty ratio, the control cycle is prolonged, and as a result, the power responsiveness is deteriorated. There is a problem.

The present invention has been made in view of such circumstances, and is to enable suppression of harmonic currents without deteriorating power responsiveness.

The present invention relates to a heater control device, wherein a predetermined lighting duty ratio is obtained for each control cycle that is an integral multiple of the cycle of the AC voltage by phase control that controls the phase angle of the AC voltage that energizes the heater. The second lighting pattern has a control means for controlling the lighting of the heater by switching between the lighting pattern of the above and the second lighting pattern, and the second lighting pattern is a half-wave section that performs phase control for each control cycle. The number of half-wave sections in which the symmetry of the positive side and the negative side of the AC voltage is maintained by the phase control is smaller than that of the first lighting pattern.

According to the present invention, it is possible to suppress the harmonic current without deteriorating the power responsiveness.

The block diagram which shows the schematic structure of the image forming apparatus which concerns on embodiment of this invention. The block diagram which shows the main part structure of the heater control device which concerns on 1st Embodiment. The figure which shows the 1st lighting pattern table. The figure which shows the 2nd lighting pattern table. The figure which shows the 3rd lighting pattern table. The figure which shows the 4th lighting pattern table. The flowchart which shows the heater control method which concerns on 1st Embodiment. The block diagram which shows the main part structure of the heater control device which concerns on 2nd Embodiment. The flowchart which shows the heater control method which concerns on 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

<Image forming apparatus according to the embodiment of the present invention>
As shown in FIG. 1, the image forming apparatus 100 includes a scanner unit 10 that optically reads an image formed on a recording material (for example, “transfer paper”) which is a sheet-shaped recording medium, and a scanner unit 10. An engine unit 20 that transfers a toner image corresponding to an image after performing predetermined image processing on a scanned image to a recording material, and a paper feed tray 30 as a recording material accommodating unit for storing the recording material. The engine unit 20 comprises a fixing device 50 for fixing the toner image transferred to the recording material. The heater control device according to the embodiment of the present invention is provided in the fixing device 50.

The scanner unit 10 optically scans the recording material on which the image is formed, converts the information attached to the recording material into an image signal, and outputs the information to the engine unit 20.

The engine unit 20 as an image forming unit performs image processing such as color conversion and gradation correction on the image signal output from the scanner unit 10, and images an electrostatic latent image according to the image after the image processing. An image is formed on the carrier, and toner, which is an deposit as a imaging material, is attached to the imaged electrostatic latent image to form a toner image. The engine unit 20 further transfers the formed toner image from the paper feed tray 30 to a recording material as a medium conveyed via the transfer path 40, and transfers the recording material to the fixing device 50 via the transfer path 40. Send out towards.

The fixing device 50 applies heat from the cylindrical fixing roller 51a and pressure from the pressurizing roller 51b to the recording material to which the toner image is attached, and fixes the toner image attached to the recording material by heat and pressure. , Discharge the paper toward the output tray.

<Heater control device according to the first embodiment>
Next, the heater control device according to the first embodiment of the present invention will be described. FIG. 2 is a block diagram showing a main configuration of a heating control device 60, which is a heater control device according to the first embodiment of the present invention.

As shown in FIG. 2, the heating control device 60 is provided in the fixing device 50 and includes a triac 54, a temperature sensor 55, a control unit 56, and a zero cross detection unit 57. The heating control device 60 is a device that controls the heating operation (lighting operation, energizing operation) of the heater 52 that heats the fixing roller 51a, which is a heating member that heats the recording material. The heater 52 is controlled by the heating control device 60 to control a heating state (lighting state, energized state) for heating the fixing roller 51a and a non-heating state (lighting state, non-energized state).

The fixing roller 51a receives heat from the heater 52 and rotates while being in pressure contact with the pressure roller 51b (FIG. 1) to fix the toner image transferred to the recording material. The fixing roller 51a is an example of a heating member.

Further, the heater 52 is an example of a heating means for heating the fixing roller 51a as a heating member. The heater 52 as a heating means is built in, for example, the fixing roller 51a. The heat of the heater 52 is a temperature at which the toner image attached to the recording material is melted by heat via the fixing roller 51a. The heater 52 is a heat source that heats the fixing roller 51a to fix the toner image on the recording material. As the heater 52, for example, a halogen heater that heats by radiant heat generated when the halogen lamp is turned on is used.

The AC power supply 53 supplies an AC voltage to the heater 52. In the present embodiment, it is assumed that an AC voltage that changes in a sinusoidal shape with time is supplied. Further, in the present embodiment, a cycle for controlling the heating operation of the heater 52 is defined as a “control cycle” based on the cycle of the voltage waveform related to the supply voltage from the AC power supply 53. That is, the cycle when the heating operation of the heater 52 is controlled as feedback control is based on the voltage waveform cycle related to the AC voltage from the AC power supply 53. In the present embodiment, for example, two cycles (four half-wave sections) of the AC voltage from the AC power supply 53 are set as one control cycle. The control cycle is not limited to the above example as long as it is an integral multiple of the cycle of the supply voltage used for heating the heater 52. The AC power supply 53 may share the operating power supply supplied to the image forming apparatus 100 and the operating power supply supplied to the fixing device 50, or may be provided individually.

The triac 54 is a switching means, and switches (on / off) the AC voltage supplied from the AC power supply 53 at a timing instructed by the control unit 56. Then, the triac 54 supplies the switched AC voltage to the heater 52. When the triac 54 is on, the heater 52 is in a lit state (energized state) and generates heat. Then, when the triac 54 is off, the heater 52 is turned off (non-energized state).

The temperature sensor 55 is an example of the temperature detecting means, and measures the surface temperature of the fixing roller 51a. The temperature sensor 55 has, for example, a built-in thermistor whose resistance value changes according to the temperature, and measures the surface temperature of the fixing roller 51a based on the resistance value of the thermistor. The temperature sensor 55 may be built in the fixing roller 51a. Further, the temperature sensor 55 may be installed at a position facing the surface of the fixing roller 51a to measure the surface temperature of the fixing roller 51a in a non-contact manner. The surface temperature of the fixing roller 51a measured by the temperature sensor 55 is acquired by the control unit 56.

In the zero cross detection unit 57, the timing when the AC voltage supplied from the AC power supply 53 crosses 0 volt, that is, the timing when the positive side (positive voltage) shifts to the negative side (negative voltage), or the timing when the negative side (negative voltage) is positive. Detects the timing of shifting to the side (positive voltage). The timing at which the supply voltage crosses 0 volt is hereinafter referred to as "zero cross timing". Then, when the zero-cross detection unit 57 detects the zero-cross timing, the zero-cross detection unit 57 outputs a zero-cross detection signal to the control unit 56.

The control unit 56 as a control means determines the timing of switching the AC voltage based on the surface temperature of the fixing roller 51a measured by the temperature sensor 55 and the timing of the zero cross of the AC voltage detected by the zero cross detection unit 57. .. Then, the control unit 56 operates the triac 54 based on the determined timing.

The control unit 56 is an information processing device implemented as a computer in which a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an input / output interface are connected via a bus. Consists of equivalent hardware. Further, the functional block realized by the control unit 56 is realized by the CPU as a hardware resource reading and executing the program stored in the ROM.

The control unit 56 has the following functional blocks realized by hardware resources and a computer program. That is, the control unit 56 includes a heating control unit 561, a lighting pattern storage unit 562, a continuous use number counter 563, a maximum continuous use number setting value storage unit 564, and a lighting pattern switching determination unit 565.

The heating control unit 561 selects a lighting pattern table in which a specific lighting pattern is stored based on the surface temperature of the fixing roller 51a detected by the temperature sensor 55 and the determination result notified from the lighting pattern switching determination unit 565. do. The specific lighting pattern is a voltage waveform pattern specified based on the above determination result from the lighting pattern table stored in the lighting pattern storage unit 562. In the present embodiment, the specific lighting pattern is advantageous for suppressing even-order harmonic currents, is disadvantageous for suppressing odd-order harmonic currents, and is advantageous for suppressing odd-order harmonic currents. Yes, it includes a lighting pattern that is disadvantageous for suppressing even-order harmonic currents. The heating control unit 561 controls the switching operation of the triac 54 based on the selected specific lighting pattern.

A lighting pattern table is stored in the lighting pattern storage unit 562 as a storage means. The lighting pattern table controls the phase angle of the AC voltage energized from the AC power supply 53 to the heater 52 by the switching operation of the triac 54, so that the AC voltage energized to the heater 52 has a predetermined lighting duty ratio for each control cycle. It is a table that stores the lighting pattern, which is the data to be used. There are a plurality of lighting patterns, and there are a plurality of lighting pattern tables in which each is stored. In the present embodiment, the first lighting pattern, which is advantageous for suppressing the even-order harmonic current and is disadvantageous for suppressing the odd-order harmonic current, is advantageous for suppressing the odd-order harmonic current, and is advantageous for suppressing the even-order harmonic current. There are four lighting pattern tables that hold four lighting patterns consisting of second to fourth lighting patterns that are disadvantageous in suppressing harmonic currents. However, this is just an example, and a lighting pattern that is disadvantageous for suppressing odd-order harmonic currents, a lighting pattern that is advantageous for suppressing odd-order harmonic currents, and a lighting pattern that is disadvantageous for suppressing even-order harmonic currents. , Each may be one or more. Details of these lighting patterns and lighting pattern tables will be described later.

The continuous use count counter 563 counts the number of continuous lighting controls according to the lighting pattern after the heating control unit 561 starts the heater lighting control according to any lighting pattern. In the present embodiment, the continuous use count counter 563 has a first counting means for counting the number of continuous lighting controls according to the first lighting pattern, a second counting means for counting the number of continuous lighting controls according to the second lighting pattern, and a third lighting pattern. A third counting means for counting the number of continuous lighting controls according to the method and a fourth counting means for counting the number of times for continuous lighting control according to the fourth lighting pattern are included.

The maximum continuous use number setting value storage unit 564 stores the set value of the maximum continuous use number of each lighting pattern. In the present embodiment, the first set value storage unit that stores the first set value which is the set value of the maximum continuous use number of the first lighting pattern, and the second setting which is the set value of the maximum continuous use number of the second lighting pattern. The second set value storage unit that stores the value, the third set value storage unit that stores the third set value which is the set value of the maximum continuous use number of the third lighting pattern, and the setting of the maximum continuous use number of the fourth lighting pattern. A fourth set value storage unit for storing a fourth set value, which is a value, is included.

The lighting pattern switching determination unit 565 determines whether or not the count value of the continuous use count counter 563 exceeds the set value stored in the maximum continuous use count setting value storage unit 564, and determines whether or not the determination result exceeds the set value stored in the heating control unit 561. Notify to. In the present embodiment, the lighting pattern switching determination unit 565 determines whether or not the count value of the first counting means exceeds the first set value, and notifies the heating control unit 561 of the determination result. The count value of the second determination means and the third counting means, which determines whether or not the count value of the second counting means exceeds the second set value and notifies the heating control unit 561 of the determination result, sets the third set value. It is determined whether or not it has exceeded, and it is determined whether or not the count values of the third determination means and the fourth counting means which notify the heating control unit 561 of the determination result exceed the fourth set value, and the determination result is heated. A fourth determination means for notifying the control unit 561 is configured.

The heating control unit 561 is used when any of the first determination means, the second determination means, the third determination means, and the fourth determination means notifies the determination result that the set value of the maximum number of continuous uses has been exceeded. Lighting control is performed by switching the lighting pattern. The details of this lighting control switching will be described later.

<Lighting pattern table>
Here, the lighting patterns stored in each lighting pattern table stored in the lighting pattern storage unit 562 will be described with reference to FIGS. 3 to 6.

3, FIG. 4, FIG. 5, and FIG. 6 show the first lighting pattern table, the second lighting pattern table, in which the first lighting pattern, the second lighting pattern, the third lighting pattern, and the fourth lighting pattern are stored, respectively. It is a figure which shows the 3rd lighting pattern table and the 4th lighting pattern table. Here, for convenience of explanation, the waveform of the AC voltage shown as the first to fourth lighting patterns in these figures is based on the data on the lighting pattern table, that is, the lighting pattern itself, but the lighting pattern 54. This is an example of the waveform of the voltage supplied to the heater 52 when the above is switched. Further, the ratio of the voltage waveform for each half wave in each lighting pattern is the energization rate.

The first lighting pattern is a lighting pattern that is advantageous for suppressing even-order harmonic currents and disadvantageous for suppressing odd-order harmonic currents. Further, the second lighting pattern, the third lighting pattern, and the fourth lighting pattern are all advantageous in suppressing odd-order harmonic currents and disadvantageous in suppressing even-order harmonic currents. That is, the first lighting pattern is an example of the first lighting pattern according to the present invention, and the second lighting pattern, the third lighting pattern, and the fourth lighting pattern are all of the second lighting pattern according to the present invention. This is an example.

As shown in FIG. 3, in the first lighting pattern stored in the first lighting pattern table 5621, all half-wave sections of the control cycle, that is, the first half-wave section a and the second half-wave section b , The third half wave section c and the fourth half wave section d are subjected to phase control, and the energization rate is uniformly increased in each half wave section. Here, the case where the lighting duty ratio, that is, the average value of the energization rate in each half-wave section for each control cycle is 10%, 50%, and 90% is illustrated (with respect to FIGS. 4, 5, and 6 described below). The same applies). The heating control unit 561 selects a lighting pattern having a required lighting duty ratio based on the surface temperature of the fixing roller 51a detected by the temperature sensor 55.

In the first lighting pattern, since the power distribution for each half-wave section is uniform, the symmetry between the plus side and the minus side for each half-wave section is maintained, and the generation of even-order harmonics can be suppressed. Therefore, it is advantageous for suppressing even-order harmonic currents. However, since phase control is performed for each half-wave section, odd-order harmonics increase. Therefore, it is disadvantageous for suppressing odd-order harmonic currents.

As shown in FIG. 4, in the second lighting pattern stored in the second lighting pattern table 5622, the first half of the control cycle (first half wave section a and second half wave) depends on the lighting duty ratio. Phase control is performed in the section b) or the latter half (third half wave section c and fourth half wave section d). That is, first, phase control is performed in the first half-wave section a and the second half-wave section b to increase the energization rate in those sections. During this period, phase control is not performed in the third half wave section c and the fourth half wave section d, and the energization rate is fixed at 0%. When the energization rate of the first half wave section a and the second half wave section b reaches 100% (lighting Duty ratio is 50%), the energization rate of the first half wave section a and the second half wave section b is 100%. In addition to fixing to, phase control is performed in the third half wave section c and the fourth half wave section d to increase the energization rate in the third half wave section c and the fourth half wave section d. That is, the second lighting pattern is a lighting pattern in which phase control is performed in two half-wave sections of AC voltage every other cycle.

In this second lighting pattern, the number of phase controls in the half-wave section for each control cycle is two, which is less than that of the first lighting pattern, so that the odd-order harmonics are smaller than those of the first lighting pattern. Therefore, it is advantageous for suppressing odd-order harmonic currents.

As shown in FIG. 5, in the third lighting pattern stored in the third lighting pattern table 5623, phase control is first performed in the first half wave section a and the third half wave section c, and these sections are performed. Increase the energization rate of. During this period, phase control is not performed in the second half wave section b and the fourth half wave section d, and the energization rate is fixed at 0%. When the energization rate of the first half wave section a and the third half wave section c reaches 100% (lighting Duty ratio is 50%), the energization rate of the first half wave section a and the third half wave section c is 100%. In addition to fixing to, phase control is performed in the second half wave section b and the fourth half wave section d to increase the energization rate in the second half wave section b and the fourth half wave section d. That is, the third lighting pattern is a pattern in which phase control is performed in one half-wave section of each period of the AC voltage.

Similar to the second lighting pattern, this third lighting pattern also has two phase controls in the half-wave section for each control cycle, which is less than the first lighting pattern, and therefore has odd-numbered harmonics more than the first lighting pattern. Less. Therefore, it is advantageous for suppressing odd-order harmonic currents. In addition, since the current is applied every other half-wave section, the inrush current is smaller than that of the second lighting pattern.

As shown in FIG. 6, in the fourth lighting pattern stored in the fourth lighting pattern table 5624, phase control is first performed in the first half wave section a, and the energization rate in that section is increased. .. During this period, phase control is not performed in the other three half-wave sections, and the energization rate is fixed at 0%. Then, when the energization rate of the first half wave section a reaches 100% (lighting duty ratio is 25%), the energization rate of the first half wave section a is fixed to 100%, and the phase is set in the second half wave section b. Control is performed to increase the energization rate in the second half wave section b. Then, when the energization rate of the second half wave section b reaches 100% (lighting duty ratio is 50%), phase control is performed in the third half wave section c to increase the energization rate of the third half wave section c. To go. After that, the energization rate is similarly increased in the third half wave section c and the fourth half wave section d. That is, the fourth lighting pattern is a pattern in which phase control is performed in one half-wave section of the AC voltage every other cycle.

In this fourth lighting pattern, the number of phase controls in the half-wave section for each control cycle is one, which is less than that of the first to third lighting patterns. Less. Therefore, among the first to fourth lighting patterns, it is most advantageous for suppressing odd-order harmonic currents.

In addition, in the same lighting duty ratio of the lighting patterns stored in each of the above lighting pattern tables, the power supplied to the heater is made equal. Further, for each lighting pattern, it is necessary to adjust the energization rate according to the actual heater and set the power supply.

<Heater control method according to the first embodiment>
The first lighting pattern, which is a lighting pattern that is advantageous for suppressing even-numbered harmonic currents and is disadvantageous for suppressing odd-numbered harmonic currents, or even-numbered harmonic currents that are advantageous for suppressing even-numbered harmonic currents. When the lighting control of the heater 52 is performed by continuously using a lighting pattern that is disadvantageous for suppressing the harmonic current, for example, the second lighting pattern, the odd-numbered or even-numbered harmonic currents may not satisfy the regulation.

Therefore, in the heater control method according to the present embodiment, every time the heater lighting control using the first lighting pattern is continuously performed N times (the first set value described above), the heater lighting control is continuously performed using the second lighting pattern. Perform M times (the second set value described above). Hereinafter, it will be described with reference to the flowchart shown in FIG. This flow is executed by the control unit 56 of the heating control device 60.

First, the heating control unit 561 counts the count value n of the first counting means for counting the number of times of continuous use of the first lighting pattern in the continuous use number counter 563, and the second counting means for counting the number of times of continuous use of the second lighting pattern. The count value m of is cleared to zero (step S1).

Next, the heating control unit 561 monitors the presence or absence of a lighting request for the heater 52 (step S2). While there is no lighting request (step S2: No), the count value n of the first counting means and the count value m of the second counting means are cleared to zero (step S3), and the monitoring of the lighting request is continued.

If a lighting request is made (step S2: Yes), the lighting pattern switching determination unit 565 determines whether or not the count value n of the first counting means is N or less (step S4). That is, whether or not the number of times of continuous use of the first lighting pattern is equal to or less than the first set value N, which is the set value of the maximum number of times of continuous use of the first lighting pattern stored in the maximum number of times of continuous use setting value storage unit 564. judge. The lighting pattern switching determination unit 565 notifies the heating control unit 561 of the determination result.

If the count value n of the first counting means is equal to or less than the first set value N (step S4: Yes), the heating control unit 561 controls the heater by the first lighting pattern stored in the lighting pattern storage unit 562. (Step S5), when the lighting control is completed, the count value n of the first counting means is incremented by 1 (step S6), and the process returns to step S2.

When the count value n of the first counting means exceeds the first set value N, the heating control unit 561 controls the lighting of the heater according to the second lighting pattern stored in the lighting pattern storage unit 562 (step S7). ), When the lighting control is completed, the count value m of the second counting means is incremented by 1 (step S8). Then, it is determined whether or not the count value m of the second counting means is M or less (step S9). That is, whether or not the number of times of continuous use of the second lighting pattern is equal to or less than the second set value M, which is the set value of the maximum number of times of continuous use of the second lighting pattern stored in the maximum number of times of continuous use set value storage unit 564. judge.

If the count value m of the second counting means is equal to or less than the second set value M (step S9: Yes), the process returns to step S2 as it is. If the count value m of the second counting means exceeds the second set value M (step S9: No), the count value n of the first counting means and the count value m of the second counting means are cleared to zero. (Step S10), the process returns to step S2.

As described above, according to the heater control device according to the first embodiment of the present invention and the heater control method executed by the device, it is advantageous to suppress even-order harmonic currents and odd-order harmonics. The number of consecutive uses of each of the lighting pattern that is disadvantageous for suppressing wave current and the lighting pattern that is advantageous for suppressing odd-order harmonic current and is disadvantageous for suppressing even-order harmonic current is less than or equal to the preset maximum value. It is limited to. Therefore, the timing at which the odd-order harmonic current increases and the timing at which the even-order harmonic current increases are dispersed, so that the power responsiveness deteriorates even in a short control cycle of about a quarter wave of the AC voltage. Harmonic current regulation can be met without

<Heater control device according to the second embodiment>
Next, the heater control device according to the second embodiment of the present invention will be described.
FIG. 8 is a block diagram showing a main configuration of a heating control device 60, which is a heater control device according to a second embodiment of the present invention. In this figure, the same or corresponding parts as those in FIG. 2 (heater control device according to the first embodiment) are designated by the same reference numerals as those in FIG. 2, and the description of these parts is omitted or omitted. Simplify.

As shown in FIG. 8, the heating according to the first embodiment is that the control unit 56 in the heating control device 60, which is the heater control device according to the present embodiment, includes the linear speed set value storage unit 566. This is a major configuration difference from the control device 60.

The linear velocity set value storage unit 566 holds the linear velocity set value of the recording material on which the toner image is fixed by the fixing device 50. The line speed values are set to low line speed, medium line speed, and high line speed according to, for example, the type of recording material (plain paper, thick paper, thin paper, etc.) conveyed from the paper feed tray 30. Further, the maximum continuous use number setting value storage unit 564 stores the set value of the maximum continuous use number for each of the low line speed, the middle line speed, and the high line speed of the recording material. In the present embodiment, as the first set value N of the maximum number of continuous uses of the first lighting pattern, the first set value N ₁ for low line speed, the first set value N ₂ for medium line speed, and high line speed The first set value N _{3 of} is the second set value M of the maximum number of continuous uses of the second lighting pattern, the second set value M ₁ for low line speed, the second set value M ₂ for medium line speed, The second set value M ₃ for high line speed is stored.

<Heater control method according to the second embodiment>
Next, the heater control method according to the present embodiment will be described. The heater lighting control procedure of the heater control device according to the present embodiment is basically the same as the heater lighting control procedure of the heater control device according to the first embodiment. That is, a lighting pattern that is advantageous for suppressing even-order harmonic currents and is disadvantageous for suppressing odd-order harmonic currents, and an even-numbered harmonic current that is advantageous for suppressing odd-numbered harmonic currents. The number of consecutive uses of each lighting pattern, which is disadvantageous for suppression, is limited to a preset maximum value or less.

The main difference from the heater control method according to the first embodiment is that in the present embodiment, the set value of the maximum number of continuous uses of each lighting pattern differs according to the linear velocity of the recording material in the fixing device 50. be. Hereinafter, it will be described with reference to the flowchart shown in FIG.

In this figure, steps S101, S102, and S103 are the same as steps S1, S2, and S3 in FIG. 7, respectively, and thus description thereof will be omitted. In step S104, the heating control unit 561 determines whether or not the linear velocity of the recording material in the fixing device 50 is a low linear velocity based on the set value of the linear velocity set value storage unit 566 (step S104).

When the line speed is low (step S104: Yes), the heating control unit 561 sets the first set value N of the maximum number of continuous uses of the first lighting pattern to the line speed set value storage unit 566 for low line speed. The first set value N _{1 of the above is selected, and the second set value M 1} for low linear speed is selected as the second set value M of the maximum number of continuous uses of the second lighting pattern (step S105).

If the linear velocity is not low (step S104: No), the heating control unit 561 determines whether or not the linear velocity is medium (step S106). In the case of the middle line speed (step S106: Yes), the heating control unit 561 sets the first set value N of the maximum number of continuous uses of the first lighting pattern from the line speed set value storage unit 566 to the middle line speed. The first set value N _{2 of the above is selected, and the second set value M 2} for the median speed is selected as the second set value M of the maximum number of continuous uses of the second lighting pattern (step S105).

When the speed is not the middle line speed (step S106: No), the heating control unit 561 sets the heating control unit 561 as the first set value N of the maximum number of continuous uses of the first lighting pattern, and sets the line speed set value storage unit. The first set value N _{3 for high line speed is selected from 566, and the second set value M 3} for high line speed is selected as the second set value M for the maximum number of continuous uses of the second lighting pattern (step S105). ).

After the heating control unit 561 executes any of steps S105, S107, and S108, the lighting pattern switching determination unit 565 determines whether or not the count value n of the first counting means is equal to or less than the first set value N (step). S109). This process is the same as step S4 in FIG.

Here, low-speed maximum continuous use count of the first lighting pattern, medium speed, the first set value N ₁ for _high-speed, N 2, _{the relationship} of _{N 3,} and the maximum continuous use count of the second lighting pattern Low _{The relationship between the second set values M 1} , M ₂ , and M ₃ for line speed, medium line speed, and high line speed will be described. As the linear velocity of the recording material in the fixing device 50 is slower, a lighting pattern having a lower lighting duty ratio is used. Therefore, when lighting control is performed with the second lighting pattern, odd-numbered harmonics are likely to increase. Therefore, the slower the line speed, the smaller the number of times the second lighting pattern is continuously used, and the more times the first lighting pattern is continuously used, so that the initial setting values for each are determined. That is, the relationship _{is "N 1} > N ₂ > N ₃ " and "M ₁ <M ₂ <M _3".

Returning to the description of FIG. If the count value n of the first counting means is equal to _{or less than the first set value N (N 1} or N ₂ or N ₃ ) (step S109: Yes), the heating control unit 561 is stored in the lighting pattern storage unit 562. The heater is controlled to be lit according to the first lighting pattern (step S110), and when the lighting control is completed, the count value n of the first counting means is incremented by 1 (step S111), and the process returns to step S102.

When the count value n of the first counting means exceeds the first set value N, the heating control unit 561 controls lighting of the heater according to the second lighting pattern stored in the lighting pattern storage unit 562 (step S112). ), When the lighting control is completed, the count value m of the second counting means is incremented by 1 (step S113). Then, it is determined whether or not the count value m of the second counting means is M (M ₁ or M ₂ or M ₃ ) or less (step S114). That is, whether or not the number of times of continuous use of the second lighting pattern is equal to or less than the second set value M, which is the set value of the number of times of continuous lighting control by the second lighting pattern stored in the maximum number of times of continuous use setting value storage unit 564. judge.

If the count value m of the second counting means is equal to or less than the second set value M (step S114: Yes), the process returns to step S102 as it is. If the count value m of the second counting means exceeds the second set value M (step S114: No), the count value n of the first counting means and the count value m of the second counting means are cleared to zero. (Step S115), the process returns to step S102.

As described above, according to the heater control device according to the second embodiment of the present invention and the heater control method executed by the device, the heater control device according to the first embodiment and the device thereof are executed. In addition to the effect of the heater control method, the lighting pattern can be selected according to the linear velocity of the recording material in the fixing device 50. Therefore, the odd-order due to the use of the second lighting pattern having a low lighting duty ratio. It has the effect of suppressing the increase in harmonics.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the technical gist thereof, and the technical concept included in the claims is included in the technical concept. All of the matters are the subject of the present invention. Since the above-described embodiment shows a suitable example, those skilled in the art can realize various modified examples from the disclosed contents. Such modifications are also included in the technical scope described in the claims.

Hereinafter, modification examples will be given.
(1) In the flowchart shown in FIG. 7, as a lighting pattern that is advantageous for suppressing odd-order harmonic currents and disadvantageous for suppressing even-order harmonic currents, a third lighting pattern is used instead of the second lighting pattern. A lighting pattern or a fourth lighting pattern is used.
(2) In the flow shown in FIG. 7, the lighting pattern to be switched with the first lighting pattern is not fixed to any one of the second to fourth lighting patterns, but two or more are used in order.
(3) In the flowchart shown in FIG. 9, the linear speed is set to 2 or 4 or more.
(4) In the flow shown in FIG. 7 and the flow shown in FIG. 9, the second lighting pattern and the third lighting pattern are switched, and the third lighting pattern and the fourth lighting pattern are switched.

10: Scanner unit 20: Engine unit 30: Paper feed tray 40: Transport path 50: Fixing device 51a: Fixing roller 51b: Pressurizing roller 52: Heater 53: AC power supply 54: Triac 55: Temperature sensor 56: Control unit 57: Zero cross detection unit 60: Heating control device 100: Image forming device 561: Heating control unit 562: Lighting pattern storage unit 563: Continuous use count counter 564: Maximum continuous use count setting value storage unit 565: Lighting pattern switching determination unit 566: Line Speed setting value storage unit
5621: 1st lighting pattern table 5622: 2nd lighting pattern table 5623: 3rd lighting pattern table 5624: 4th lighting pattern table

Japanese Unexamined Patent Publication No. 2012-132946

Claims (9)

A first lighting pattern and a second lighting pattern in which a predetermined lighting duty ratio is obtained for each control cycle that is an integral multiple of the AC voltage cycle by phase control that controls the phase angle of the AC voltage that energizes the heater. It has a control means for controlling the lighting of the heater by switching between the pattern and the pattern.
The second lighting pattern includes the number of half-wave sections for which phase control is performed for each control cycle, and the number of half-wave sections for which the positive and negative symmetry of the AC voltage is maintained by the phase control. , A heater control device characterized in that the number of lighting patterns is less than that of the first lighting pattern. When the control means reaches the maximum number of continuous uses of the preset first lighting pattern, the control means switches from the first lighting pattern to the second lighting pattern, and the preset second lighting pattern The heater control device according to claim 1, wherein when the maximum number of times of continuous use is reached, the second lighting pattern is switched to the first lighting pattern. The heater control device according to claim 1 or 2, wherein the first lighting pattern is a pattern for performing phase control in all half-wave sections of an AC voltage. The heater control device according to claim 1 or 2, wherein the second lighting pattern is a pattern in which phase control is performed in two half-wave sections of AC voltage every other cycle. The heater control device according to claim 1 or 2, wherein the second lighting pattern is a pattern in which phase control is performed in one half-wave section of each period of the AC voltage. The heater control device according to claim 1 or 2, wherein the second lighting pattern is a pattern in which phase control is performed in one half-wave section of AC voltage every other cycle. An image forming part that forms an image by adhering a imaging material to a medium,
It has a fixing device for fixing the imaging material attached to the medium to the medium by heating.
An image forming apparatus, characterized in that the heater control device according to any one of claims 1 to 6 is used to control the lighting of a heater that lights the fixing roller of the fixing device by an AC voltage. 2. The image forming apparatus according to claim 7, which is cited. The heater is operated by using a first lighting pattern in which a predetermined lighting duty ratio is obtained every control cycle that is an integral multiple of the cycle of the AC voltage by phase control that controls the phase angle of the AC voltage that energizes the heater. The first lighting control step for lighting control and
Using a second lighting pattern in which a predetermined lighting duty ratio is obtained for each control cycle that is an integral multiple of the cycle of the AC voltage by phase control that controls the phase angle of the AC voltage that energizes the heater. A second lighting control step that controls the lighting of the heater, and
Have,
In the second lighting pattern, the number of half-wave sections for which phase control is performed for each control cycle and the number of half-wave sections for which the symmetry of the plus side and the minus side is maintained by the phase control are the first. A heater control method characterized by having less than the lighting pattern of.

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