JP2021107859A - Image forming apparatus, control method, and program - Google Patents

Abstract

To prevent sudden change of a current used in a fixing device during change of a current-carrying pattern.SOLUTION: A control unit can execute first start phase control C11 of, before first continuous current-carrying control C1 of continuously carrying a first AC current A1 to a first heater, performing the current-carrying in a part of a sine wave of the first AC current, and second end phase control C22 of, after second continuous current-carrying control C2 of continuously carrying a second AC current A2 to a second heater, performing the current-carrying in a part of a sine wave of the second AC current, and controls the current-carrying to the heaters on the basis of a current-carrying pattern determined for every control period T. The current-carrying pattern is a prescribed current-carrying pattern (III) in which the first start phase control is started at the start of the control period and the second end phase control is ended at the end of the control period, the pattern in which an initial peak current value β in the first start phase control matches a last peak current value α of combination of the first and second AC currents at the end of the second end phase control.SELECTED DRAWING: Figure 8

Description

The present invention relates to an image forming apparatus including a fixing device having a plurality of heaters, and a control method and a program in the image forming apparatus.

Conventionally, as an image forming apparatus, an image forming apparatus is known in which the energization patterns of two heaters are switched at a control cycle (see Patent Document 1). In this technology, continuous energization control in which alternating current is continuously energized for each of the two heaters within the control cycle, and per half wave of alternating current by changing the phase angle before continuous energization control. A soft start that gradually increases the amount of energization of the alternating current and a soft stop that gradually decreases the amount of energization per half wave of the alternating current by changing the phase angle after continuous energization control are executed. .. Then, within the control cycle, a period is provided for stopping the energization of each heater after the soft stop for each heater is completed.

Japanese Unexamined Patent Publication No. 2010-096969

However, if a period for stopping the energization of each heater is provided in the latter half of the control cycle, the current used in the fixing device suddenly changes when the energization is restarted in the next control cycle, that is, when the energization pattern is switched. , There is a risk of a momentary voltage drop that causes flicker.

Therefore, an object of the present invention is to suppress a sudden change in the current used in the fixing device when switching the energization pattern.

In order to solve the above problems, the image forming apparatus according to the present invention fixes a developer image forming portion that forms a developing agent image on a sheet and a developer image formed by the developing agent image forming portion on the sheet. It includes a device and a control unit.
The fixing device has an output peak in a heating unit and a first region of the heating unit, and outputs to a first heater for heating the heating unit and a second region different from the first region of the heating unit. A second heater having a peak and heating the heating unit, a pressurizing unit that sandwiches a sheet between the heating unit, and a first temperature detecting unit that detects the temperature of at least a part of the first region. It has a second temperature detection unit that detects at least a part of the temperature of the second region.
The control unit includes a first continuous energization control in which a first alternating current is continuously energized in the first heater, and a first phase control at the start before the first continuous energization control. The first phase control at the start of energizing the heater with a part of the sinusoidal wave of the first alternating current and the first phase control at the end after the first continuous energization control are performed on the first heater. On the other hand, phase control at the end of the first phase in which a part of the sinusoidal wave of the first alternating current is energized, second continuous energization control in which the second alternating current is continuously energized in the second heater, and the second continuous energization. The second start phase control performed before the energization control, the second start phase control in which the second heater is energized with a part of the sinusoidal wave of the second alternating current, and the second continuous energization. The second termination phase control performed after the control, which is the second termination phase control in which a part of the sinusoidal wave of the second alternating current is energized to the second heater, can be executed. To the first heater and the second heater based on the energization pattern determined for each control cycle from the first detection temperature detected by the first temperature detection unit and the second detection temperature detected by the second temperature detection unit. Controls the energization of.
The energization pattern is a defined energization pattern in which the first start phase control is started at the start of the control cycle and the second end phase control is terminated at the end of the control cycle. A specified energization pattern in which the first peak current value in the time phase control and the final peak current value of the combination of the first AC current and the second AC current at the end of the second end phase control match. Have.

According to this configuration, when the energization pattern is determined to be the specified energization pattern in both the predetermined control cycle and the next control cycle of the predetermined control cycle, the second end phase control in the predetermined control cycle is performed. The final peak current value of the combination of the first alternating current and the second alternating current at the end coincides with the first peak current value of the first phase control at the start of the next control cycle. Therefore, it is possible to suppress a sudden change in the current used in the fixing device when switching the energization pattern.

Further, the control unit may gradually reduce the amount of energization of the second alternating current per half wave by changing the phase angle in the second end phase control.

According to this, in the phase control at the second end, the amount of energization per half wave of the second alternating current is gradually reduced, so that it is possible to suppress a sudden change in the current flowing through the second heater.

Further, the control unit satisfies the first condition of T1 + T2 <T, where T is the control cycle, T1 is the period for executing the first continuous energization control, and T2 is the period for executing the second continuous energization control. In this case, the second continuous energization control may be started immediately after the end of the first continuous energization control.

According to this, by starting the second continuous energization control immediately after the end of the first continuous energization control, the first continuous energization control and the second continuous energization control are continuously performed within the control cycle, and within the control cycle. Since the continuous energization control is performed once in the above, the momentary voltage drop generated in the control cycle can be suppressed to one time.

Further, when the first condition is satisfied, the control unit may stop the energization without executing the phase control at the first end after the first continuous energization control.

According to this, when the first condition is satisfied, the phase control at the first end is not executed after the first continuous energization control, so that the peak of the combined current becomes too large in the second continuous energization control. It can be suppressed.

Further, the peak of the current in the energization in the second continuous energization control is larger than the peak of the current in the energization in the first continuous energization control, and the control unit sets the control cycle to T and the first continuous energization control. When the second condition of T1 + T2 ≧ T and T1> T2 is satisfied, where T1 is the period for executing the above and T2 is the period for executing the second continuous energization control, the first continuous energization control is performed. The second continuous energization control may be started during the execution.

Further, when the second condition is satisfied and T1 <T, the control unit may execute the first end-time phase control after the first continuous energization control.

According to this, since the first end-time phase control is executed after the first continuous energization control, it is possible to suppress a sudden change in the current flowing through the first heater.

Further, the control method according to the present invention includes a developer image forming unit that forms a developer image on the sheet, a fixing device that fixes the developer image formed by the developer image forming unit on the sheet, and a control unit. The fixing device has a heating unit, a first heater having an output peak in the first region of the heating unit, and heating the heating unit, and a second heater different from the first region of the heating unit. A second heater having an output peak in the region and heating the heating portion, a pressurizing portion sandwiching a sheet between the heating portion, and a first temperature for detecting at least a part of the temperature of the first region. A first unit having a detection unit and a second temperature detection unit that detects at least a part of the temperature in the second region, and the control unit continuously energizes the first heater with a first alternating current. The continuous energization control and the first phase control at the start before the first continuous energization control, at the first start of energizing the first heater with a part of a sinusoidal wave of the first alternating current. Phase control and first end phase control performed after the first continuous energization control, and first end phase control in which a part of a sinusoidal wave of a first alternating current is energized to the first heater. The second continuous energization control in which the second alternating current is continuously energized in the second heater and the second start phase control performed before the second continuous energization control are performed with respect to the second heater. The second start phase control that energizes a part of the sinusoidal wave of the second alternating current, and the second end phase control that is performed after the second continuous energization control. A control method by the control unit in an image forming apparatus capable of performing a second end-time phase control in which a part of a sinusoidal wave of an alternating current is energized, and a first detected by the first temperature detection unit. Based on the energization pattern determined for each control cycle from the 1 detection temperature and the second detection temperature detected by the second temperature detection unit, the energization of the first heater and the second heater is controlled, and the energization pattern Is a defined energization pattern in which the first start phase control is started at the start of the control cycle and the second end phase control is terminated at the end of the control cycle, and is the first start phase control. Has a defined energization pattern in which the first peak current value in the above and the final peak current value of the combination of the first alternating current and the second alternating current at the end of the second end phase control match.

Further, the program according to the present invention includes a developer image forming unit that forms a developer image on a sheet, a fixing device that fixes a developer image formed by the developer image forming unit on the sheet, and a control unit. The fixing device has a heating unit, a first heater having an output peak in the first region of the heating unit, and heating the heating unit, and a second region different from the first region of the heating unit. A second heater that has an output peak and heats the heating unit, a pressurizing unit that sandwiches a sheet between the heating unit, and a first temperature detection that detects at least a part of the temperature of the first region. A first continuous unit having a unit and a second temperature detecting unit that detects a temperature of at least a part of the second region, and the control unit continuously energizes the first heater with a first alternating current. The energization control and the first phase control at the start before the first continuous energization control, the first phase at which the first heater is energized with a part of a sinusoidal wave of the first alternating current. Control and first phase control at the end, which is performed after the first continuous energization control, and first phase control at which the first heater is energized with a part of a sinusoidal wave of the first alternating current. The second continuous energization control for continuously energizing the second alternating current to the second heater and the second start phase control performed before the second continuous energization control for the second heater. The second start phase control that energizes a part of the sinusoidal wave of the second alternating current and the second end phase control that is performed after the second continuous energization control are the second with respect to the second heater. A program for operating the control unit in an image forming apparatus capable of executing a second end-time phase control in which a part of a sinusoidal wave of an alternating current is energized, and the control unit is subjected to the first temperature. The first heater and the second heater are energized based on an energization pattern determined for each control cycle from the first detection temperature detected by the detection unit and the second detection temperature detected by the second temperature detection unit. It functions as a means for controlling, and the energization pattern is a defined energization pattern in which the first start phase control is started at the start of the control cycle and the second end phase control is ended at the end of the control cycle. Therefore, the first peak current value in the phase control at the first start and the final peak current value of the combination of the first alternating current and the second alternating current at the end of the phase control at the second end. Has a specified energization pattern that matches.

According to the control method or program described above, when the energization pattern is determined to be the specified energization pattern in both the predetermined control cycle and the next control cycle of the predetermined control cycle, the second in the predetermined control cycle. The final peak current value of the combination of the first AC current and the second AC current at the end of the phase control at the end coincides with the first peak current value of the phase control at the first start in the next control cycle. Therefore, it is possible to suppress a sudden change in the current used in the fixing device when switching the energization pattern.

According to the present invention, it is possible to suppress a sudden change in the current used in the fixing device when switching the energization pattern.

It is a figure which shows the laser printer which concerns on this embodiment. It is a figure which shows the fixing device. It is a graph which shows the output of each heater. It is a block diagram which shows the structure of a control part. It is a figure which shows the table for determining the energization pattern. It is a figure which shows the energization pattern in the column surrounded by the frame X of FIG. It is a figure which shows the energization pattern in the column surrounded by the frame Y of FIG. It is a figure (a) which shows the energization control in a pattern III, the figure (b) which shows the composite waveform in the first phase control at a start time, and the figure (c) which shows the last half wave of a composite waveform enlarged. It is a figure which shows the energization control in the pattern I. It is a flowchart which shows the operation of a control part. It is a figure which shows the mode in which the execution period of the first termination phase control and the execution period of the second termination phase control overlap.

Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1, the laser printer 1 is an example of an image forming apparatus that forms an image on a sheet S, and is an example of a main body housing 2, a sheet supply unit 3, and a developing agent image forming unit. It includes a PR, a fixing device 8, and a control unit 100.

The sheet supply unit 3 is a mechanism for supplying the sheet S to the process unit PR, and is provided at the lower part in the main body housing 2. The sheet supply unit 3 includes a supply tray 31 for accommodating the sheet S, a sheet pressing plate 32, and a supply mechanism 33. The supply mechanism 33 includes a pickup roller 33A, a separation roller 33B, a first transfer roller 33C, and a registration roller 33D. In the sheet supply unit 3, the sheet S in the supply tray 31 is brought to the pickup roller 33A by the sheet pressing plate 32 and sent to the separation roller 33B by the pickup roller 33A. The sheet S is separated into one sheet by the separation roller 33B, and is conveyed by the first transfer roller 33C. After aligning the positions of the tips of the sheets S, the registration roller 33D conveys the sheets S toward the process unit PR. Here, the transport direction of the sheet S is defined as the transport direction, and the direction orthogonal to the transport direction in the plane of the sheet S is defined as the width direction.

The process unit PR has a function of forming a developer image on the sheet S. The process unit PR includes an exposure apparatus 4 and a process cartridge 5.

The exposure apparatus 4 is arranged in the upper part of the main body housing 2 and includes a laser light source (not shown), a polygon mirror, a lens, a reflecting mirror, etc., which are indicated by omitting reference numerals. In the exposure apparatus 4, the laser beam based on the image data emitted from the laser light source is scanned on the surface of the photoconductor drum 61 to expose the surface of the photoconductor drum 61.

The process cartridge 5 is arranged below the exposure apparatus 4, and is removable from the main body housing 2 through an opening formed when the front cover 21 provided in the main body housing 2 is opened. The process cartridge 5 includes a drum unit 6 and a developing unit 7.

The drum unit 6 includes a photoconductor drum 61, a charger 62, and a transfer roller 63. The developing unit 7 is removable from the drum unit 6, and includes a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, a developer accommodating unit 74 for accommodating a developer which is a dry toner, and an agitator 75. And have.

In the process cartridge 5, the surface of the photoconductor drum 61 is uniformly charged by the charger 62 and then exposed by the laser beam from the exposure apparatus 4, so that the photoconductor drum 61 is statically charged based on the image data. An electro-latent image is formed. Further, the developer in the developer accommodating portion 74 is supplied to the developing roller 71 via the supply roller 72 while being stirred by the agitator 75, and as the developing roller 71 rotates, the developing roller 71 and the layer thickness regulating blade It enters between 73 and is supported on the developing roller 71 as a thin layer having a constant thickness.

The developer supported on the developing roller 71 is supplied from the developing roller 71 to the electrostatic latent image formed on the photoconductor drum 61. As a result, the electrostatic latent image is visualized and a developer image is formed on the photoconductor drum 61. After that, the sheet S supplied from the sheet supply unit 3 is conveyed between the photoconductor drum 61 and the transfer roller 63, so that the developer image formed on the photoconductor drum 61 is transferred onto the sheet S. NS.

The fixing device 8 is a device for fixing the developer image formed by the process unit PR on the sheet S. The fixing device 8 includes a heating unit 81 that heats the sheet S, and a pressurizing unit 82 that sandwiches the sheet S between the heating units 81.

The heating unit 81 is a rotatable cylindrical heating roller, and is made of metal or the like. Inside the heating unit 81, a first heater H1 and a second heater H2 for heating the heating unit 81 are provided. The pressurizing unit 82 is a rotatable pressurizing roller, and has an elastic layer made of elastically deformable rubber or the like on its surface. In the fixing device 8, the sheet S on which the developer image is transferred is conveyed between the heating unit 81 and the pressurizing unit 82, so that the developer image is heat-fixed on the sheet S. The sheet S on which the developer image is heat-fixed is discharged onto the discharge tray 22 by the second transfer roller 23 and the discharge roller 24.

As shown in FIG. 2, the fixing device 8 includes the above-mentioned heating unit 81, the first heater H1 and the second heater H2, and further includes a first temperature detection unit ST1 and a second temperature detection unit ST2. There is.

The first heater H1 is a halogen lamp and has an output peak in the first region 81A including the central portion in the width direction of the heating portion 81 (see FIG. 3). The first heater H1 includes a glass tube H11 and a filament H12 provided in the glass tube H11. In the filament H12, the light emitting portions are concentrated in the central portion in the width direction as compared with the respective end portions in the width direction.

The second heater H2 is a halogen lamp, and has an output peak in the second regions 81B and 81C, which are on the end side of the first region 81A of the heating unit 81 (see FIG. 3). The second heater H2 includes a glass tube H21 and a filament H22 provided in the glass tube H21. In the filament H22, the light emitting portions are concentrated at each end portion in the width direction as compared with the central portion in the width direction.

Here, the width direction of the heating unit 81 means a direction along the rotation axis of the heating unit 81, and means the same direction as the width direction of the sheet S. The first region 81A of the heating portion 81 is a range including the center in the width direction of the heating portion 81, and the second region 81B on one end side of the heating portion 81 is the edge 81D and the first edge 81D on one end side of the heating portion 81. It is a range between the region 81A and the region 81A. The second region 81C on the other end side of the heating portion 81 is a range between the end edge 81E on the other end side of the heating portion 81 and the first region 81A.

As shown by the solid line in FIG. 3, the output of the first heater H1 has a distribution that is highest in the center in the width direction and gradually decreases toward both ends in the width direction. As a result, in the first heater H1, the heating capacity of the heating unit 81 for the first region 81A is larger than the heating capacity for the second regions 81B and 81C. As shown by the broken line, the output of the second heater H2 has a distribution higher on the end side than in the center in the width direction. As a result, in the second heater H2, the heating capacity of the heating unit 81 for the second regions 81B and 81C is larger than the heating capacity for the first region 81A. The range in which the output of the first heater H1 is maximized and the range in which the output of the second heater H2 is maximized are set so as not to overlap.

The output of the first heater H1 in the second regions 81B and 81C is 30% or less of the output in the first region 81A, and the output of the second heater H2 in the first region 81A is 80 of the output in the second regions 81B and 81C. It is less than%.

Examples of the method of detecting the output of each of the heaters H1 and H2 include a method of arranging an optical sensor for detecting the light of the heater at a predetermined distance from the heater and detecting the amount of the light. Here, the predetermined distance is the distance from the heater to the inner peripheral surface of the heating unit 81.

As shown in FIG. 2, the first temperature detection unit ST1 is a sensor that detects at least a part of the temperature of the first region 81A of the heating unit 81. The first temperature detection unit ST1 is in non-contact with the heating unit 81. Specifically, the first temperature detection unit ST1 is arranged at a distance from the outer peripheral surface of the heating unit 81.

The second temperature detection unit ST2 is a sensor that detects at least a part of the temperature of the second region 81B on one end side of the heating unit 81. The second temperature detection unit ST2 is in contact with the second region 81B of the heating unit 81. The second temperature detection unit ST2 is displaced from the maximum region SW of the sheet S that can be fixed by the fixing device 8 to the end edge 81D side on one end side.

As the first temperature detection unit ST1 and the second temperature detection unit ST2, for example, a thermistor or the like can be used.

As shown in FIG. 4, the control unit 100 includes an ASIC 110 and an energization circuit 120. The ASIC 110 has a CPU 111 and a heater controller 112. The energization circuit 120 is a circuit including a switching circuit for switching the input AC voltage between the energized state and the non-energized state, and is connected to the heaters H1 and H2 and the ASIC 110.

The CPU 111 is implemented as a function in the ASIC 110. The CPU 111 outputs the first target temperature, which is the target temperature of the first region 81A, and the second target temperature, which is the target temperature of the second region 81B, to the heater controller 112. Each target temperature is a command value in the feedback process when the heater controller 112 executes energization control to the first heater H1 and the second heater H2.

The heater controller 112 is a function or circuit built in the ASIC 110, and controls each heater by controlling the energization circuit 120 so that the temperature detected by each temperature detection unit ST1 and ST2 becomes the respective target temperature. H1 and H2 are energized. Specifically, the heater controller 112 determines the duty ratio of the AC voltage that energizes each heater H1 and H2 based on the detected temperature and the target temperature, and performs feedback processing that controls the energizing circuit 120 at the determined duty ratio. .. The feedback process performed by the heater controller 112 may be mounted on a chip external to the ASIC 110, or may be executed by the CPU 111.

The control unit 100 includes a print command output from an external computer, a detection temperature detected by the first temperature detection unit ST1 and the second temperature detection unit ST2, and a program stored in a storage unit such as ROM 113 or RAM 114. Control is executed by performing various arithmetic processes based on the data. In other words, the control unit 100 functions as a means for executing various controls by operating according to the program.

The control unit 100 has a first energization pattern P determined for each control cycle T from the first detection temperature detected by the first temperature detection unit ST1 and the second detection temperature detected by the second temperature detection unit ST2. It has a function of controlling energization of the heater H1 and the second heater H2. Here, the control cycle T is a predetermined unit time in which the energization patterns of the heaters H1 and H2 are set. The control unit 100 has a first deviation D1 which is a deviation between the first target temperature and the first detection temperature, a second deviation D2 which is a deviation between the second target temperature and the second detection temperature, and a table shown in FIG. Based on the above, the energization pattern P is selected.

The table shown in FIG. 5 is a table set in advance by an experiment, a simulation, or the like, and is stored in the ROM 113 or the RAM 114. Here, the magnitude relation of the numerical values a to i shown in FIG. 5 is a <b <c <d <e <f <g <i. The magnitude relationship between the numerical values j to r is j <k <l <m <n <o <p <q <r.

The energization pattern P is a pattern indicating an execution period of various energization controls executed for each heater H1 and H2 within the control cycle T. As the energization pattern P, a plurality of types of patterns such as pattern I, pattern II, pattern III, pattern IV, pattern V, and pattern VI are set. Note that FIG. 5 shows a part of the energization patterns P among the plurality of types, but in addition to this, the energization pattern P is applied to at least one of the heaters H1 and H2 from the beginning to the end of the control cycle T. A pattern to stop the energization of is set.

As shown in FIGS. 6 and 7, the energization pattern P is a first energization pattern P1 for controlling energization of the first heater H1 and a second energization pattern for controlling energization of the second heater H2. It has P2. Here, FIG. 6 shows the energization patterns P (I to IV) in the column surrounded by the broken line frame X in FIG. Further, FIG. 7 shows the energization patterns P (I to III, V) in the column surrounded by the broken line frame Y in FIG.

In the first energization pattern P1, periods T1 and T11 to T13 for executing a plurality of types of energization control for the first heater H1 are selectively set in the control cycle T. Hereinafter, the period T1 is also referred to as a "first full lighting period T1", the period T11 is also referred to as a "first start period T11", the period T12 is also referred to as a "first end period T12", and the period T13 is also referred to as a "first extinguishing period T13".

The first start period T11 is a period during which the first start phase control described later is executed. The first full lighting period T1 is a period for executing the first continuous energization control described later. The first end period T12 is a period for executing the first end time phase control described later. The first extinguishing period T13 is a period during which the energization of the first heater H1 is stopped. The first full lighting period T1 is set to a longer period as the first deviation D1 is larger. The relationship between the first full lighting period T1 and the first deviation D1 is not limited to the frame X in FIG. 5, and has the same relationship in the columns arranged vertically.

In the second energization pattern P2, periods T2, T21 to T23 for executing a plurality of types of energization control for the second heater H2 are selectively set in the control cycle T. Hereinafter, the period T2 is also referred to as a "second full lighting period T2", the period T21 is also referred to as a "second start period T21", the period T22 is also referred to as a "second end period T22", and the period T23 is also referred to as a "second extinguishing period T23".

As shown in FIG. 7, the second start period T21 is a period during which the second start phase control described later is executed. The second full lighting period T2 is a period for executing the second continuous energization control described later. The second end period T22 is a period during which the second end phase control described later is executed. The second extinguishing period T23 is a period during which the energization of the second heater H2 is stopped. As shown in FIG. 7, the second full lighting period T2 is set to a longer period as the second deviation D2 is larger. The relationship between the second full lighting period T2 and the second deviation D2 is not limited to the frame Y in FIG. 5, and has the same relationship in the columns arranged side by side.

As shown in FIG. 6, the pattern I is a pattern in which the first full lighting period T1 and the second full lighting period T2 do not overlap. Specifically, in pattern I, the second full lighting period T2 is started immediately after the first full lighting period T1.

In the first energization pattern P1 of the pattern I, the first start period T11, the first full lighting period T1 and the first extinguishing period T13 are set, and the first end period T12 is not set. In the second energization pattern P2 of the pattern I, all the periods T2, T21 to T23 described above are set.

In the first energization pattern P1 of the pattern I, each period T11, T1 and T13 are set in the order of the first full lighting period T1 after the first start period T11 and the first extinguishing period T13 after the first full lighting period T1. Has been done. In the second energization pattern P2 of the pattern I, the second turn-off period T23 is followed by the second start period T21, the second start period T21 is followed by the second full lighting period T2, and the second full lighting period T2 is followed by the second end period T22. In this order, T23, T21, T2, and T22 are set for each period.

In the pattern I, the start time point of the first start period T11 and the start time point of the second extinguishing period T23 coincide with the start time point of the control cycle T. In pattern I, the start time point of the first full lighting period T1 and the start time point of the second start period T21 are the same. In the pattern I, the end time point of the first extinguishing period T13 and the end time point of the second end period T22 coincide with the end time point of the control cycle T.

That is, the energization pattern P of the pattern I corresponds to a defined energization pattern in which the first start phase control is started at the start of the control cycle T and the second end phase control is ended at the end of the control cycle T.

The pattern II is a pattern in which the second full lighting period T2 is started immediately after the first full lighting period T1 as in the pattern I. Specifically, the pattern II is a pattern in which the second end period T22 is removed from the pattern I. In pattern II, the end time point of the second full lighting period T2 coincides with the end time point of the control cycle T.

Pattern III is a pattern in which the first full lighting period T1 and the second full lighting period T2 overlap. Specifically, pattern III is a pattern in which the first end period T12 is added to pattern I. In pattern III, the first end period T12 is set between the first full lighting period T1 and the first extinguishing period T13. In pattern III, the start time point of the second full lighting period T2 is set after the start time point of the first full lighting period T1 and before the end time point of the first full lighting period T1. In pattern III, the end time point of the second full lighting period T2 coincides with the end time point of the first end period T12.

Further, in the pattern III, similarly to the pattern I, the start time point of the first start period T11 coincides with the start time point of the control cycle T, and the end time point of the second end period T22 coincides with the end time point of the control cycle T. I am doing it. Therefore, the energization pattern P of the pattern III also corresponds to the above-mentioned specified energization pattern.

Similar to pattern III, pattern IV is a pattern in which the first full lighting period T1 and the second full lighting period T2 overlap, and the first full lighting period T1 is set as a period from the start to the end of the control cycle T. Is. Specifically, the pattern IV is a pattern in which the first start period T11, the first extinguishing period T13, and the second extinguishing period T23 are removed from the pattern I.

In pattern IV, the start time point of the first full lighting period T1 and the start time point of the second start period T21 coincide with the start time point of the control cycle T. In pattern IV, the end time point of the first full lighting period T1 and the end time point of the second end period T22 coincide with the end time point of the control cycle T.

As shown in FIG. 7, the pattern V is a pattern in which the first full lighting period T1 and the second full lighting period T2 overlap, and the second full lighting period T2 ends from the start of the control cycle T, as in the pattern III. It is a pattern set in the period until. Specifically, the pattern V is a pattern obtained by removing the first extinguishing period T13, the second starting period T21, the second ending period T22, and the second extinguishing period T23 from the pattern III.

In the pattern V, the start time point of the second full lighting period T2 coincides with the start time point of the control cycle. In the pattern V, the end time point of the first end period T12 and the end time point of the second full lighting period T2 coincide with the end time point of the control cycle T.

Although not shown, the pattern VI is a pattern in which the first full lighting period T1 and the second full lighting period T2 are set as a period from the start to the end of the control cycle T.

The control unit 100 can execute the first continuous energization control, the second continuous energization control, and the phase control based on the energization pattern P. As shown in FIG. 8A, the first continuous energization control C1 is a control for continuously energizing the first alternating current A1 to the first heater H1. The second continuous energization control C2 is a control for continuously energizing the second alternating current A2 to the second heater H2. Here, the waveform shown in FIG. 8A is a waveform corresponding to pattern III, but individual controls such as the first continuous energization control and the second continuous energization control are similarly performed in any pattern. , Each control will be described with reference to the waveform shown in FIG. 8 (a).

The peak of the second alternating current A2 is larger than the peak of the first alternating current A1. That is, the peak of the current in the energization of the second continuous energization control C2 is larger than the peak of the current in the energization of the first continuous energization control C1.

Phase control is a control that energizes a part of a sine wave of an alternating current. More specifically, the phase control is a control in which the sine wave is energized in a portion less than the half wave (the latter half portion of the half wave). The control unit 100 supplies an alternating current to the heaters H1 and H2 based on the target phase angle θt in the phase control.

Here, the phase angle is defined as 0 ° at the end point of the predetermined half wave and 180 ° at the start point of the predetermined half wave. That is, the position of the current value 0 after the absolute value of the current value tends to decrease in the predetermined half wave is set to the phase angle 0 °, and the phase angle gradually increases from this position toward the start point of the predetermined half wave. The phase angle range is set from 0 to 180 °. The range of the phase angle used for control is 0 to 90 °.

The control unit 100 performs intermittent energization by changing or fixing the target phase angle θt to a constant value during the execution period of the phase control. The control unit 100 can execute the first start phase control C11, the first end phase control C12, the second start phase control C21, and the second end phase control C22 as phase control. ing.

The first start phase control C11 is a phase control performed before the first continuous energization control C1 and is a phase control for energizing the first heater H1 with a part of a sine wave of the first alternating current A1. .. The control unit 100 keeps the target phase angle θt constant when, for example, the first start phase control C11 is executed in the pattern I shown in FIG. 9 or the pattern III shown in FIG. That is, when the time of the first start period T11 can be set only to a very short time as in patterns I to III, the target phase angle θt is kept constant. Here, the target phase angle θt when the target phase angle θt is kept constant is set to a value less than 90 ° and larger than 0 °.

When the control unit 100 executes the first phase control C11 at the time of starting in the pattern V shown in FIG. 7, the control unit 100 changes the target phase angle θt to change the energization amount per half wave of the first alternating current A1. Gradually increase. That is, when the time of the first start period T11 can be set to a sufficiently long time as in the pattern V, the target phase angle θt is changed.

Specifically, the control unit 100 sets the target phase angle θt to 0 so that the absolute value of the current peak in each half wave gradually increases from the state where the current value is 0 toward the peak of the first alternating current A1. Gradually increase from ° to 90 °. As a method of gradually increasing the target phase angle θt, for example, a method of proportionally increasing the target phase angle θt by adding a predetermined amount from 0 °, or a logarithmically or exponentially target phase angle. Examples thereof include a method of increasing θt. Further, as a method of increasing the target phase angle θt by a predetermined amount, for example, a value obtained by dividing the phase angle 90 ° by the number of half waves that fit within the execution period (T11) of the first phase control C11 at the start is used. It can be quantitative.

The first termination phase control C12 is a phase control performed after the first continuous energization control C1 and is a phase control for energizing the first heater H1 with a part of a sine wave of the first alternating current A1. For example, when the control unit 100 executes the phase control C12 at the end of the first phase in the pattern III shown in FIG. 8, the control unit 100 gradually changes the energization amount per half wave of the first alternating current A1 by changing the target phase angle θt. Make it smaller. That is, when the time of the first end period T12 can be set to a sufficiently long time as in pattern III, the target phase angle θt is changed.

Specifically, the control unit 100 gradually sets the target phase angle θt from 90 ° to 0 ° so that the absolute value of the current peak in each half wave gradually decreases from the peak of the first alternating current A1. Make it smaller. The method of gradually decreasing the target phase angle θt includes a method of proportionally decreasing the target phase angle θt, a method of logarithmically and exponentially decreasing the target phase angle θt, and the like, as in the above-mentioned increasing method. Can be mentioned.

Further, when the control unit 100 executes the first end phase control C12 in the pattern V shown in FIG. 7, the target phase angle θt is kept constant. In the first end phase control C12 in the pattern V, the target phase angle θt may be changed so that the amount of energization per half wave gradually decreases.

The second start phase control C21 is a phase control performed before the second continuous energization control C2, and is a phase control for energizing the second heater H2 with a part of the sine wave of the second alternating current A2. be. The second start phase control C21 is the same control as the first start phase control C11. The control unit 100 changes the target phase angle θt or fixes it to a constant value according to the length of the second start period T21.

As an example, when the control unit 100 executes the second start phase control C21 in the pattern I shown in FIG. 9 or the pattern III shown in FIG. 8, the control unit 100 changes the target phase angle θt to obtain the second alternating current. The amount of current A2 per half wave is gradually increased. Specifically, the control unit 100 sets the target phase angle θt to 0 so that the absolute value of the current peak in each half wave gradually increases from the state where the current value is 0 toward the peak of the second alternating current A2. Gradually increase from °. As a method of gradually increasing the target phase angle θt, the same method as that of the first phase control C11 at the start can be mentioned.

FIG. 8B is an enlarged view showing a composite waveform of the first alternating current A1 and the second alternating current A2 in the second start period T21. FIG. 8 (c) is an enlarged view showing the last half wave of the composite waveform of FIG. 8 (b). As shown in FIGS. 8 (b) and 8 (c), in the second start phase control C21, the combined value A12 of the first alternating current A1 and the second alternating current A2 is the second alternating current. Energize so that it is below the peak PK of A2. Specifically, the control unit 100 obtains a final phase angle θe that has the same current value as the peak PK of the second AC current A2 in the last half wave of the combined value A12, and sets the final phase angle θe to the second start. The final target phase angle θt of the time phase control C21 is set. Then, the control unit 100 sequentially subtracts a predetermined amount from the final phase angle θe from the last half wave of the second start phase control C21 toward the first half wave, and subtracts a predetermined amount from the final phase angle θe to the target phase angle θt of each half wave. Set to.

As shown in FIG. 8A, the second termination phase control C22 is a phase control performed after the second continuous energization control C2, and is a thyrist wave of the second alternating current A2 with respect to the second heater H2. It is a phase control that energizes a part. The second termination phase control C22 is substantially the same as the first termination phase control C12. The control unit 100 changes the target phase angle θt or fixes it to a constant value according to the length of the second end period T22.

As an example, when the control unit 100 executes the second end phase control C22 in the pattern I shown in FIG. 9 or the pattern III shown in FIG. 8, the control unit 100 changes the target phase angle θt to obtain the second alternating current. The amount of current A2 per half wave is gradually reduced. Specifically, the control unit 100 gradually reduces the target phase angle θt from 90 ° so that the amount of energization per half wave is gradually reduced by a method substantially the same as that of the first end phase control C12.

Here, the energization pattern P of the patterns I and III is the above-mentioned specified energization pattern. The specified energization pattern is the final peak of the combination of the first peak current value β in the first start phase control C11 and the first AC current A1 and the second AC current A2 at the end of the second end phase control C22. It is set to match the current value α. In the present embodiment, since the execution periods of the phase control C11, C12, C21, and C22 are set so as not to overlap, the energization of the first heater H1 is stopped at the end of the second end phase control C22. The first alternating current A1 is 0. Therefore, in the present embodiment, the final peak current value α of the second alternating current A2 in the control cycle T is the combined value of the first alternating current A1 and the second alternating current A2 at the end of the phase control C22 at the end of the second end. It has become.

When the first condition represented by the following equation (1) is satisfied, the control unit 100 starts the second continuous energization control C2 immediately after the end of the first continuous energization control C1 as shown in FIG. do.
T1 + T2 <T ... (1)
T: Control cycle T1: First full lighting period T2: Second full lighting period

Specifically, in the present embodiment, the minimum period required to execute the first start phase control C11 is T11 _min , and the condition represented by the following equation (2) is the first condition.
T11 _min + T1 + T2 <T ... (2)

That is, the first condition does not include the conditions relating to the first end period T12, the second start period T21, and the second end period T22.

Further, when the first condition is satisfied, the control unit 100 stops the energization without executing the first end-time phase control C12 after the first continuous energization control C1. When the first condition is satisfied, the control unit 100 starts the second start phase control C21 at the same time as the start of the first continuous energization control C1.

The case where the first condition is satisfied means the case where the patterns I and II are selected based on the deviations D1 and D2. In other words, the first condition means that the first detection temperature and the second detection temperature have reached the temperature at which the patterns I and II are selected.

When the second condition having the conditions of the following equations (3) and (4) is satisfied, the control unit 100 has a second continuous energization control C1 during execution of the first continuous energization control C1, as shown in FIG. The continuous energization control C2 is started.
T1 + T2 ≧ T ・ ・ ・ (3)
T1> T2 ... (4)

Specifically, in the present embodiment, the minimum period required to execute the first start phase control C11 is T11 _min , and the condition represented by the following equation (4) is the second condition.
T11 _min + T1 + T2> T ... (4)

When the second condition is satisfied and T1 <T, the control unit 100 executes the first end-time phase control C12 after the first continuous energization control C1. When the second condition is satisfied and T1 <T, the control unit 100 stops energizing the first heater H1 after the end of the first end phase control C12. When the second condition is satisfied and T1 <T, the control unit 100 executes the second termination phase control C22 immediately after the termination of the first termination phase control C12.

The case where the second condition is satisfied means the case where the patterns III and VI are selected based on the deviations D1 and D2. In other words, the second condition means that the first detection temperature and the second detection temperature have reached the temperature at which the patterns III and VI are selected.

Further, the case where the second condition is satisfied and T1 <T means that the pattern III is selected based on the respective deviations D1 and D2. In other words, when the second condition is satisfied and T1 <T, it means that the first detection temperature and the second detection temperature are the temperatures at which pattern III is selected.

Next, the operation of the control unit 100 will be described with reference to the flowchart shown in FIG. Upon receiving the print command, the control unit 100 repeatedly executes the process shown in FIG. 10 in the control cycle T until printing is completed.

In the process shown in FIG. 10, the control unit 100 first acquires the temperature from the first temperature detection unit ST1 and the second temperature detection unit ST2 (S1). After step S1, the control unit 100 selects the energization pattern P based on the detected temperatures acquired from the temperature detection units ST1 and ST2 and the table of FIG. 5 (S2). Specifically, in step S2, the control unit 100 calculates the first deviation D1 and the second deviation D2 from each detected temperature and the target temperature, and selects the energization pattern P from the respective deviations D1 and D2 and the table.

After step S2, the control unit 100 sets the wave number and the target phase angle in each phase control based on the start periods T11 and T21 and the end periods T12 and T22 set in the energization pattern P (S3). ). After step S3, the control unit 100 executes energization control based on the energization pattern P (S4), and ends this process.

Next, a specific example of the operation of the control unit 100 will be described.
As shown in FIG. 5, when the deviation conditions are j ≦ D1 <k and d ≦ D2 <e, the control unit 100 selects the pattern I as the energization pattern P. In pattern I, as shown in FIG. 6, the first start period T11, the first full lighting period T1, the first extinguishing period T13, the second extinguishing period T23, the second start period T21, the second all lighting period T2, and The second end period T22 is set.

The control unit 100 fixes the target phase angle to a predetermined value for the first start phase control C11 executed in the first start period T11. The control unit 100 obtains the wave number from the length of each period for the second start phase control C21 executed in the second start period T21 and the second end phase control C22 executed in the second end period T22, and obtains the wave number. The target phase angle in each half wave is set based on.

After that, as shown in FIG. 9, the control unit 100 executes the energization control based on the pattern I. Specifically, the control unit 100 first starts the first start phase control C11 in a state where the energization of the second heater H2 is stopped. At this time, the control unit 100 executes the first start phase control C11 with the target phase angle constant.

The control unit 100 executes the first start phase control C11 during the first start period T11, then terminates the first start phase control C11, and terminates the first continuous energization control C1 and the second start phase control C21. Start at the same time. In the second start phase control C21, the control unit 100 gradually increases the peak of the current per half wave by gradually increasing the target phase angle. Specifically, the control unit 100 gradually increases the target phase angle so that the peak current value of the combination of the first alternating current A1 and the second alternating current A2 gradually approaches the peak current value of the second alternating current A2. do.

The control unit 100 executes the first continuous energization control C1 and the second start phase control C21 for a predetermined time (T1, T21), and then ends the first continuous energization control C1 and the second start phase control C21. .. After the end of the first continuous energization control C1 and the second start phase control C21, the control unit 100 stops energization of the first heater H1 and starts the second continuous energization control C2.

The control unit 100 executes the second continuous energization control C2 during the second full lighting period T2, and then starts the second end-time phase control C22. In the second end phase control C22, the control unit 100 gradually reduces the peak of the current per half wave by gradually reducing the target phase angle. Specifically, in the control unit 100, the peak current value α of the last half wave of the second end phase control C22 becomes a predetermined value (the same value as the first peak current value β in the first start phase control C11). As described above, the peak of the current per half wave is gradually reduced. As a result, when the next selected energization pattern P is patterns I to III, the peak current value at the end of the energization control by the current energization pattern P and the first energization control by the next selected energization pattern P Can be matched with the peak current value of.

After executing the second end phase control C22 during the second end period T22, the control unit 100 selects the next energization pattern P (for example, pattern I) and performs energization control with the selected energization pattern P.

As shown in FIG. 5, when the deviation conditions are o ≦ D1 <p and d ≦ D2 <e, the control unit 100 selects pattern III as the energization pattern P. In pattern III, as shown in FIG. 6, in addition to each period set in pattern I, a first end period T12 is set. The control unit 100 obtains the wave number from the length of the period for the first end phase control C12 executed in the first end period T12, and sets the target phase angle based on the wave number. Other phase controls are set in the same manner as when pattern I is selected.

After that, the control unit 100 executes the energization control based on the pattern III as shown in FIG. In the following description, the same operation as when the energization control is executed based on the pattern I will be omitted.

The control unit 100 ends the second start phase control C21 and starts the second continuous energization control C2 while the first continuous energization control C1 is being executed. The control unit 100 ends the first continuous energization control C1 and starts the first end-time phase control C12 while the second continuous energization control C2 is being executed. In the first end phase control C12, the control unit 100 gradually reduces the target phase angle so that the peak of the current per half wave gradually decreases toward 0.

The control unit 100 simultaneously terminates the first termination phase control C12 and the second continuous energization control C2 after the lapse of the first termination period T12 from the start of the first termination phase control C12. After the end of the first end phase control C12 and the second continuous energization control C2, the control unit 100 stops the energization of the first heater H1 and starts the second end phase control C22.

Based on the above, the following effects can be obtained in the present embodiment.
When patterns I and II are selected as the energization pattern P, the second continuous energization control C2 is started immediately after the end of the first continuous energization control C1 to cause the first continuous energization control C1 within the control cycle T. Since the second continuous energization control C2 is continuously performed and the continuous energization control is performed once in the control cycle T, the instantaneous voltage drop that occurs in the control cycle T is suppressed to one time. be able to.

When the first condition is satisfied, the phase control C12 at the end of the first end is not executed after the first continuous energization control C1, so that the peak of the combined current can be suppressed in the second continuous energization control C2.

Since the peak of the current in the energization of the second continuous energization control C2 is made larger than the peak of the current in the energization in the first continuous energization control C1, it is possible to quickly heat the second regions 81B and 81C of the heating unit 81. can.

In the second start phase control C21, energization is performed so that the combined value of the first alternating current A1 and the second alternating current A2 is equal to or less than the peak of the second alternating current A2, so that the first continuous energization control C1 And when the second start phase control C21 is being executed at the same time, the peak of the combined current can be suppressed.

Since the amount of energization of the second alternating current A2 per half wave is gradually increased in the second start phase control C21, it is possible to suppress a sudden change in the current flowing through the second heater H2.

In the first termination phase control C12 and the second termination phase control C22, the amount of energization per half wave of the alternating current is gradually reduced, so that it is possible to suppress sudden changes in the currents flowing through the heaters H1 and H2. can.

When the energization pattern P is determined to be the specified energization pattern (for example, I, III) in both the predetermined control cycle T and the next control cycle T of the predetermined control cycle T, the predetermined control cycle T is used. The final peak current value α of the combination of the first AC current A1 and the second AC current A2 at the end of the second end phase control C22 is the first of the first start phase control C11 in the next control cycle T. Consistent with the peak current value β. Therefore, it is possible to suppress a sudden change in the current used in the fixing device 8 when switching the energization pattern P.

When the second condition is satisfied and T1 <T, the first termination phase control C12 is executed after the first continuous energization control C1, so that the current flowing through the first heater H1 suddenly changes. It can be suppressed.

The present invention is not limited to the above embodiment, and can be used in various forms as illustrated below. In the following description, the same reference numerals will be given to controls and the like substantially the same as those in the above embodiment, and the description thereof will be omitted.

In the above embodiment, the energization pattern P is set so that the execution periods of the phase control do not overlap, but the present invention is not limited to this, and as shown in FIG. 11, for example, in the energization control in the pattern III, The execution period (T12) of the first termination phase control C12 and the execution period (T22) of the second termination phase control C22 may overlap.

Specifically, in the energization control in pattern III, the first end-time phase control C12 may be executed until the end time of the control cycle T. In this case, the control unit 100 adds the peak current value α1 of the last half wave in the first end phase control C12 and the peak current value α2 of the last half wave in the second end phase control C22. However, the final target phase angle θt may be set and the second end phase control C22 may be executed so as to coincide with the first peak current value β in the first start phase control C11.

In the above embodiment, the energization pattern P is determined using the table shown in FIG. 5, but the present invention is not limited to this, and for example, the energization pattern may be determined using a function or the like.

In the above embodiment, the first region 81A is a region including the central portion in the width direction of the heating portion 81, and the second regions 81B and 81C are regions that are on the end side of the first region 81A of the heating portion 81. However, the present invention is not limited to this, and the first region and the second region may be regions having different positions in the width direction.

In the above embodiment, in both the first termination phase control and the second termination phase control, the amount of alternating current energized per half wave is gradually reduced, but the present invention is not limited to this, and the first termination is not limited to this. In either the time phase control or the second end phase control, the amount of current applied per half wave of the alternating current may be gradually reduced.

In the above embodiment, the second start phase control is started at the same time as the first continuous energization control is started, but the present invention is not limited to this, and the second start phase control is performed during the execution of the first continuous energization control. Just do it. Specifically, the phase control at the time of the second start may be started after the start of the first continuous energization control.

The sheet S may be a paper such as thick paper, a postcard, or a thin paper, or may be an OHP sheet or the like.

The developer image forming unit is arbitrarily configured. For example, it may be a developer image forming unit that exposes a photosensitive drum with an LED head.

In the above embodiment, the heating roller is exemplified as the heating unit, but the present invention is not limited to this, and the heating unit includes, for example, a plate-shaped nip member heated by a heater, or a nip member and a pressurizing unit. It may be a fixing belt sandwiched between them.

In the above embodiment, the halogen lamp is exemplified as the heater, but the present invention is not limited to this, and the heater may be a solid heat generating element such as a carbon heater.

In the above embodiment, the thermistor is exemplified as the temperature detection unit, but the present invention is not limited to this, and any sensor that detects the temperature may be used.

In the above embodiment, the first temperature detection unit ST1 is not in contact with the heating unit 81, but the present invention is not limited to this, and the first temperature detection unit may be in contact with the heating unit. Further, the second temperature detection unit may be in non-contact with the heating unit.

In the above embodiment, the present invention is applied to the laser printer 1, but the present invention is not limited to this, and the present invention may be applied to other image forming devices such as a color printer, a copying machine, and a multifunction device. ..

In the above embodiment, the phase angle is set so that the phase angle gradually increases from the end point of the predetermined half wave toward the start point, but the present invention is not limited to this, and the phase angle is from the start point to the end point of the predetermined half wave. The phase angle may be set so that the phase angle gradually increases. That is, the phase angle at the start point of a predetermined half wave may be defined as 0 °, and the phase angle at the end point may be defined as 180 °. In this case, assuming that the range of the phase angle used for control is 90 ° to 180 °, the increase / decrease of the phase angle in each control may be reversed from that of the above-described embodiment.

Each element described in the above-described embodiment and modification may be arbitrarily combined and implemented.

1 Laser printer 8 Fixing device 81 Heating unit 81A 1st region 81B, 81C 2nd region 82 Pressurizing unit 100 Control unit A1 1st AC current A2 2nd AC current C1 1st continuous energization control C2 2nd continuous energization control C11 1st 1 Start phase control C12 1st end phase control C21 2nd start phase control C22 2nd end phase control H1 1st heater H2 2nd heater I, III pattern P energization pattern PR process unit S sheet ST1 1st temperature Detection unit ST2 Second temperature detection unit T Control cycle

Claims (8)

A developer image forming part that forms a developing agent image on the sheet,
A fixing device for fixing the developer image formed by the developer image forming unit on the sheet,
With a control unit
The fixing device is
With the heating part
A first heater having an output peak in the first region of the heating portion and heating the heating portion,
A second heater having an output peak in a second region different from the first region of the heating portion and heating the heating portion, and a second heater.
A pressurizing part that sandwiches the sheet between the heating part and
A first temperature detection unit that detects at least a part of the temperature in the first region,
It has a second temperature detection unit that detects at least a part of the temperature of the second region, and has a second temperature detection unit.
The control unit
The first continuous energization control in which the first alternating current is continuously energized to the first heater, and
The first phase control at the start, which is performed before the first continuous energization control, is the first phase control at which the first heater is energized with a part of a sine wave of the first alternating current.
The first termination phase control that is performed after the first continuous energization control, that is, the first termination phase control that energizes the first heater with a part of a sine wave of the first alternating current.
The second continuous energization control in which the second alternating current is continuously energized to the second heater, and
The second start phase control that is performed before the second continuous energization control, and the second start phase control that energizes the second heater with a part of the sine wave of the second alternating current.
The second termination phase control, which is performed after the second continuous energization control, is the second termination phase control in which the second heater is energized with a part of the sine wave of the second alternating current. It is possible and
The first heater and the second heater are based on an energization pattern determined for each control cycle from the first detection temperature detected by the first temperature detection unit and the second detection temperature detected by the second temperature detection unit. Control the energization to
The energization pattern is
A defined energization pattern in which the first start phase control is started at the start of the control cycle and the second end phase control is terminated at the end of the control cycle, which is the first in the first start phase control. It is characterized by having a defined energization pattern in which the peak current value of the above and the final peak current value of the combination of the first alternating current and the second alternating current at the end of the second termination phase control match. Image forming device. The image according to claim 1, wherein the control unit gradually reduces the amount of energization of the second alternating current per half wave by changing the phase angle in the phase control at the second end. Forming device. The control unit
The control cycle is T, the period for executing the first continuous energization control is T1, and the period for executing the second continuous energization control is T2.
When the first condition of T1 + T2 <T is satisfied,
The image forming apparatus according to claim 1 or 2, wherein the second continuous energization control is started immediately after the end of the first continuous energization control. The control unit
The image forming apparatus according to claim 3, wherein when the first condition is satisfied, the energization is stopped without executing the first end-time phase control after the first continuous energization control. .. The peak of the current in the energization in the second continuous energization control is larger than the peak of the current in the energization in the first continuous energization control.
The control unit
The control cycle is T, the period for executing the first continuous energization control is T1, and the period for executing the second continuous energization control is T2.
When T1 + T2 ≧ T and the second condition T1> T2 is satisfied,
The image forming apparatus according to any one of claims 1 to 4, wherein the second continuous energization control is started during the execution of the first continuous energization control. The control unit
The image according to claim 5, wherein when the second condition is satisfied and T1 <T, the first end-time phase control is executed after the first continuous energization control. Forming device. A developer image forming part that forms a developing agent image on the sheet,
A fixing device for fixing the developer image formed by the developer image forming unit on the sheet,
With a control unit
The fixing device is
With the heating part
A first heater having an output peak in the first region of the heating portion and heating the heating portion,
A second heater having an output peak in a second region different from the first region of the heating portion and heating the heating portion, and a second heater.
A pressurizing part that sandwiches the sheet between the heating part and
A first temperature detection unit that detects at least a part of the temperature in the first region,
It has a second temperature detection unit that detects at least a part of the temperature of the second region, and has a second temperature detection unit.
The control unit
The first continuous energization control in which the first alternating current is continuously energized to the first heater, and
The first phase control at the start, which is performed before the first continuous energization control, is the first phase control at which the first heater is energized with a part of a sine wave of the first alternating current.
The first termination phase control that is performed after the first continuous energization control, that is, the first termination phase control that energizes the first heater with a part of a sine wave of the first alternating current.
The second continuous energization control in which the second alternating current is continuously energized to the second heater, and
The second start phase control that is performed before the second continuous energization control, and the second start phase control that energizes the second heater with a part of the sine wave of the second alternating current.
The second termination phase control, which is performed after the second continuous energization control, is the second termination phase control in which the second heater is energized with a part of the sine wave of the second alternating current. It is a control method by the control unit in a possible image forming apparatus, and is
The first heater and the second heater are based on an energization pattern determined for each control cycle from the first detection temperature detected by the first temperature detection unit and the second detection temperature detected by the second temperature detection unit. Control the energization to
The energization pattern is
A defined energization pattern in which the first start phase control is started at the start of the control cycle and the second end phase control is terminated at the end of the control cycle, which is the first in the first start phase control. It is characterized by having a defined energization pattern in which the peak current value of the above and the final peak current value of the combination of the first alternating current and the second alternating current at the end of the second termination phase control match. Control method to do. A developer image forming part that forms a developing agent image on the sheet,
A fixing device for fixing the developer image formed by the developer image forming unit on the sheet,
With a control unit
The fixing device is
With the heating part
A first heater having an output peak in the first region of the heating portion and heating the heating portion,
A second heater having an output peak in a second region different from the first region of the heating portion and heating the heating portion, and a second heater.
A pressurizing part that sandwiches the sheet between the heating part and
A first temperature detection unit that detects at least a part of the temperature in the first region,
It has a second temperature detection unit that detects at least a part of the temperature of the second region, and has a second temperature detection unit.
The control unit
The first continuous energization control in which the first alternating current is continuously energized to the first heater, and
The first phase control at the start, which is performed before the first continuous energization control, is the first phase control at which the first heater is energized with a part of a sine wave of the first alternating current.
The first termination phase control that is performed after the first continuous energization control, that is, the first termination phase control that energizes the first heater with a part of a sine wave of the first alternating current.
The second continuous energization control in which the second alternating current is continuously energized to the second heater, and
The second start phase control that is performed before the second continuous energization control, and the second start phase control that energizes the second heater with a part of the sine wave of the second alternating current.
The second termination phase control, which is performed after the second continuous energization control, is the second termination phase control in which the second heater is energized with a part of the sine wave of the second alternating current. A program that operates the control unit in a possible image forming apparatus.
The control unit
The first heater and the second heater are based on an energization pattern determined for each control cycle from the first detection temperature detected by the first temperature detection unit and the second detection temperature detected by the second temperature detection unit. To function as a means to control the energization to
The energization pattern is
A defined energization pattern in which the first start phase control is started at the start of the control cycle and the second end phase control is terminated at the end of the control cycle, which is the first in the first start phase control. It is characterized by having a defined energization pattern in which the peak current value of the above and the final peak current value of the combination of the first alternating current and the second alternating current at the end of the second termination phase control match. Program to do.

Images