JP4922842B2 - Fixing apparatus, image forming apparatus, temperature control method, program, and storage medium - Google Patents

Description

  The present invention relates to a fixing device and the like, and relates to a fixing device, an image forming apparatus, a temperature control method, a program, and a storage medium that can reduce power consumption.

There is known a fixing device that transfers an unfixed image (toner image) formed on a photosensitive drum in an image forming unit using an electrophotographic process onto a recording material such as paper and fixes the image on the recording material. For example, in a fixing device that uses a halogen heater as a heat source, the temperature of the fixing device is detected by a temperature detection element, and the detected temperature is used to control power supply to the halogen heater based on a calculation result such as PID calculation. Then, temperature control is performed so that the temperature of the fixing device becomes a target temperature.
In order to reduce power consumption in such a fixing device, only one of the two heaters is heated alternately between the time when one image is transferred to the intermediate transfer member and the time when the next image is read and transferred. At the same time, there has been proposed a fixing device that performs control so that heating by two heaters does not occur (see, for example, Patent Document 1).

  However, since the simultaneous lighting of the heaters is prohibited in the control described in Patent Document 1, a situation frequently occurs in which the heaters that are supposed to be turned on as a result of the calculation must be turned off. There is a problem that the fixing to the site becomes unstable.

  Further, time proportional control is known in which an ON operation period (operation amount) of a predetermined control cycle is determined according to a calculation result. FIG. 19 shows an example of conventional time proportional control. In such control, the ON operation period is determined in the range of 0 to 100% in accordance with the calculation result in the control cycle, and the heater is turned on during the ON operation period.

In FIG. 19, in a fixing device having two heaters, the on operation period of one heater 1 is based on the start end of the control cycle, and the on operation period of the other heater 2 is based on the end of the control cycle. As a result, the power consumption is reduced by reducing the overlap period in which the two heaters 1 and 2 are turned on.
JP 2000-019926 A

  However, if the end of the control cycle is used as a reference for the ON operation period as in the heater 2 of FIG. 19, the heater 2 is turned ON during the ON operation period based on the calculation result after the OFF period from the start end of the control cycle. In other words, there is a problem that there is a delay from when the preferred on-operation period is calculated until the heater 2 is turned on. This delay does not occur when the entire control cycle is set to the ON operation period, but it is considered that there are many situations where the delay occurs because the control becomes rare after the temperature is stabilized. Further, since the delay becomes longer as the control period is longer, the temperature followability is further deteriorated depending on the control period, for example, the temperature of the heater 2 is changed.

  In view of the above problems, the present invention provides a fixing device, an image forming apparatus, a temperature control method, a program, and a storage medium that reduce power consumption by suppressing a decrease in temperature followability in a fixing device having a plurality of heaters. For the purpose.

  In view of the above problems, the present invention is mounted on a mounted apparatus (for example, the image forming apparatus 100), and records an unfixed image on a recording material by heating it with a plurality of heating units (for example, the heaters 11 and 12). In a fixing device for fixing to a material, a calculation unit (for example, a temperature control unit 23) that independently calculates an operation amount of a plurality of heating units for each control cycle, and an energization period corresponding to the operation amount from the beginning of the control cycle A control unit that controls energization of a plurality of heating units independently; and a margin power detection means (for example, a power consumption output device 24) that detects a margin power that can be used by the fixing device out of the power that can be supplied by the mounted device. When the surplus power is less than the predetermined value, the control unit has a low priority so that the end of the energization period of the predetermined low priority heating unit substantially coincides with the end of the control cycle. The power supply is controlled, That.

  According to the present invention, if the surplus power is sufficient, the energization control is performed from the beginning of the control cycle, so that the temperature follow-up property is maintained and the image quality does not deteriorate. Is controlled based on the rear end of the control cycle, so that power consumption can be reduced. Therefore, both temperature followability and power consumption can be achieved.

  In one embodiment of the present invention, a power consumption calculation unit that calculates power consumption consumed by the fixing device in a control cycle based on an operation amount; and a determination unit that determines whether the power consumption is greater than the marginal power. In addition, when the power used is larger than the surplus power, there is provided an overlapping period shortening means for shortening an overlapping period in which a plurality of heating units overlap and are energized and controlled.

  According to the present invention, when the power consumption exceeds the surplus power, the total power consumption of the fixing device can be suppressed because the period is shortened from the overlap period.

  Moreover, in one form of this invention, an overlap period shortening means shortens the electricity supply time of a heating part with a low priority, and shortens an overlap period.

  According to the present invention, since the energization time of the heating unit having a low priority is shortened, stable fixing can be performed even when power is saved.

  According to another aspect of the present invention, there is provided a priority switching unit that acquires the size of the recording material and switches the priority of the plurality of heating units according to the size.

  According to the present invention, the degree of influence of the heating unit on fixing varies depending on the arrangement position of the heating unit and the size of the recording material that passes, but the priority of the heating unit is switched according to the size of the recording material to be fixed. Thus, temperature followability can be maintained.

  In one embodiment of the present invention, a priority heater selection table in which priorities of a plurality of heating units are set in association with operating conditions such as when a mounted device is started up, in standby, in a fixing process, and the like is stored. Heater selection table storage means, and priority switching means for referring to the priority heater selection table based on operating conditions and switching the priority of a plurality of heating units.

The purpose of heating differs depending on the operating conditions of the image forming apparatus, such as uniformly warming the fixing device members when starting up the image forming apparatus and giving priority to fixing properties during the fixing process. By switching the priority of the heating unit according to the operating conditions of the image forming apparatus such as start-up, standby, energy-saving mode, and fixing process, the target temperature can be stably tracked even with power saving.
According to another aspect of the present invention, there is provided a priority switching unit that switches the priority of the plurality of heating units in accordance with the fixing process time.

  The temperature distribution of the recording material changes depending on the arrangement position of the heating unit and the continuous time of the fixing process. Therefore, by switching the heating priority of each heating unit according to the continuous time of the fixing process, the followability of the target temperature can be maintained stably even with power saving.

  Moreover, in one form of this invention, it has the priority setting means which sets the priority of a some heating part arbitrarily, It is characterized by the above-mentioned.

  The degree of influence of each heating unit on the fixing property is determined by a plurality of factors such as fixing process time and recording material size. By making it possible to arbitrarily set the priority of each heating unit, the user can finely adjust the fixing property.

  Further, in one aspect of the present invention, when the image quality priority mode or the power saving mode is set and the mode selection unit is set, and the image quality priority mode is selected, the control unit may have a marginal power equal to or less than a predetermined value. A plurality of heating units are independently energized and controlled for an energization period corresponding to an operation amount from the start end of the control cycle.

  By selecting the mode, the heating timing of each heating unit can be arbitrarily set, and the user can select image quality priority or power priority according to the power environment of the place of use.

  In one embodiment of the present invention, an operation amount correction table storage unit that stores an operation amount correction table in which correction amounts of operation amounts of a plurality of heating units are set in association with the fixing process time, and based on the fixing process time. An operation amount correction unit that refers to the operation amount correction table and corrects the operation amounts of the plurality of heating units is provided.

  By switching the energization time of each heating unit according to the fixing process time, power distribution corresponding to the temperature drop due to the fixing process time is performed, and the follow-up of the target temperature can be stably maintained even with power saving.

  In one embodiment of the present invention, an operation amount correction table storage unit that stores an operation amount correction table in which correction amounts of operation amounts of a plurality of heating units are set in association with the size of the recording material, and the size of the recording material And an operation amount correction means for referring to the operation amount correction table and correcting the operation amounts of the plurality of heating units.

By switching the energization time of each heating unit according to the size of the recording material, power distribution according to the size of the recording material is performed, and the follow-up of the target temperature can be maintained stably even with power saving.
Moreover, in one form of this invention, it has the upper limit time setting means which sets the upper limit of the energization time of a some heating part, and a control part makes an energization period below an upper limit irrespective of the operation amount which the calculating part computed. It is characterized by limiting.

  According to the present invention, the upper limit of the energization time of each heating unit can be arbitrarily set, so that the fixability can be finely adjusted according to the power environment at the place of use.

Further, in one aspect of the present invention, when there is an overlap period in which a plurality of heating units overlap and are energized, the control unit shortens the energization time of one or more heating units so that the overlap period is eliminated.
It is characterized by that.

  Unlike the fixing process, the waiting time or the like does not require accuracy in the temperature follow-up property, so that power can be saved by controlling not to heat all the heaters at the same time.

  In a fixing device having a plurality of heaters, it is possible to provide a fixing device, an image forming apparatus, a temperature control method, a program, and a storage medium that reduce power consumption by suppressing a decrease in temperature followability.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings.

  The fixing device 10 according to the present embodiment controls the heating timing of the heater according to the power consumption of the load other than the fixing device 10, and when there is a margin in power, the start end of the control cycle is used as a reference for the on operation period. When there is no margin in power, the overlapping period in which the two heaters overlap and become the ON operation period is minimized, thereby suppressing power consumption and realizing stable fixing.

  FIG. 1 is a schematic configuration diagram of a fixing device 10 mounted on an image forming apparatus. Although the case where there are two heaters 11 and 12 will be described, three or more may be used. When there is a margin in the power that can be used by the fixing device 10, both the heaters 11 and 12 are controlled with the start end of the control cycle as a reference for the ON operation period, and when there is no margin in the power, only the heater 11 or 12 with higher priority is controlled. The beginning of the cycle is used as a reference for the ON operation period. Then, the overlapping period can be minimized by switching the heater 11 or 12 having a low priority to the heating timing using the end of the control cycle as a reference of the ON operation period. In addition, the heater 11 or 12 having a high priority can minimize a decrease in temperature followability by using the start end of the control cycle as a reference for the on-operation period. Note that the term “terminating the end of the ON operation period” refers to controlling the heating timing so that the ON operation period ends at the end of the control cycle.

  The fixing device 10 will be described. The toner image has already been transferred to the recording material 9 such as paper, and the recording material 9 is conveyed to the two rotating rollers 13 and 14. A heater 11 is provided in the rotating roller 13 and a heater 12 is provided in the rotating rotor 14, respectively, and they are heated to a predetermined temperature by a control method described later. Since the toner image is melted by this temperature, the toner image is fixed on the recording material 9 by the heat and pressure by the rotating rollers 13 and 14.

  The rotating rollers 13 and 14 are coated with rubber on a metal pipe, and include heaters 11 and 12 such as halogen heaters on the inside of the metal pipe, and the heat of the heaters 11 and 12 is transmitted to the surfaces of the rotating rollers 13 and 14. It is supposed to be. The temperatures of the surfaces of the rotating rollers 13 and 14 are detected by temperature sensors 15 and 16, respectively, and are controlled by the control unit 22 to a predetermined temperature by a control method such as feedback control.

  In FIG. 1, the heaters 11 and 12 are provided in the rotary rollers 13 and 14 that press the recording material 9, respectively, but a plurality of heaters 11 and 12 are provided in one axial direction of the rotary roller 13 or 14. You may set up.

  The heaters 11 and 12 may use heating resistors, Peltier elements, electromagnetic induction heating, or the like. Also, a flash heating device that heats the recording material 9 in a non-contact manner is known. However, when the heaters 11 and 12 are used to assist heating of the flash heating device, the control method of this embodiment is used. It can be suitably applied.

  In the fixing device 10 of the present embodiment, priority is set so that either the heater 11 or 12 is preferentially heated, and a default priority is set in advance, which will be described later. The priority can be made variable as described in the example. For example, the heater 11 that heats the rotating roller 13 that is in contact with the surface of the recording material 9 on which the toner image is transferred has a high priority by default.

  FIG. 2 is a block diagram of the fixing device 10. Here, the heaters 11 and 12 are halogen heaters. On the power supply circuit 25, a circuit for generating power from electric power supplied from the AC power supply 26 and a circuit for independently driving the heaters 11 and 12 are arranged. The power supply circuit 25 includes a relay that cuts off the power supply from the AC power supply 26 and a switch circuit that turns on / off the power supply to the heaters 11 and 12. That is, the heaters 11 and 12 heat the rotating rollers 13 and 14 while the switch circuit is on.

  A keyboard 27a and a touch panel display 27b are connected to the control unit 22, and setting input at the time of image formation described later can be performed by operating the keyboard 27a or the display 27b. Therefore, these constitute the input device 27. In addition, an operation menu, an operation status, and the like are displayed on the display 27b.

  The target temperature setting means 21 connected to the control unit 22 inputs the target temperature to the control unit 22 according to the operation mode (sleep mode, standby mode, etc.) of the image forming apparatus or the like. For example, when the image forming apparatus is in operation, the target temperature is about 180 degrees, and in the sleep mode or the like, a lower temperature is the target temperature.

  The temperature control unit 23 calculates an operation amount by, for example, PID from the temperatures of the rotary rollers 13 and 14 detected by the temperature sensors 15 and 16 and the target temperature. The calculation result is input to the control unit 22, and the control unit 22 determines the ON operation period of the two heating rollers based on the operation amount, and controls ON / OFF of the switch circuit according to the ON operation period.

PID will be briefly described. The PID calculation calculates the difference between the current deviation and the previous deviation with respect to the manipulated variable (P) according to the difference from the target temperature, the manipulated variable (I) according to the residual deviation from the target temperature, and a sudden disturbance. The corresponding operation amount (D) is calculated to calculate the final operation amount. Here, the following formula was used as an example.
PID operation amount =
(Kp × (T1 + T0) + Ki × (target temperature−T0) + Kd × (2 × T1−T0−T2)
Kp: proportional constant Ki: integral constant Kd: differential constant T0: current heater temperature T1: previous heater temperature T2: previous heater temperature The temperature control unit 23 calculates the above equations for each of the temperature sensors 15 and 16. The operation amounts of the heaters 11 and 12 are calculated. The constants Kp, Ki, and Kd are set by a tuning method such as a step response method.

  In this embodiment, the operation amount is calculated using PID calculation, but the calculation method is not limited, and the operation amount may be calculated by P calculation or PI calculation.

A power consumption detection device 24 is connected to the control unit 22, and the power consumption acquired by the power consumption detection device 24 by monitoring the power supply circuit 25 is input. The power consumption detector 24 includes, for example, an ammeter and a voltmeter, and independently detects the power consumption of the heaters 11 and 12 from the product thereof. The power supply circuit 25 supplies power to devices other than the heaters 11 and 12 (computer, display, scanner, transport motor, etc.). The power consumption detection device 24 also uses the power consumed by these devices. To detect. Hereinafter, the power consumption by the devices other than the heaters 11 and 12 is the device power consumption, and the amount of power that can be supplied to the fixing device 10 with respect to the supplyable power that can be supplied by the power supply circuit 25 is the marginal power Watt_max. Call each one.
Available power = Device power consumption + Marginal power Watt_max
The control unit 22 calculates the marginal power Watt_max that can be supplied to the fixing device 10 from the current device power consumption with respect to the power that can be supplied by the power supply circuit 25.

  The control unit 22 is a computer including a CPU 22a that executes the program 51, a RAM 22c that is a working memory of the CPU 22a, and a ROM 22b that stores the program 51 and the like. When the CPU 22a executes the program 51, the power consumption calculation means 53 that calculates the power used by the fixing device 10 in a predetermined control cycle, the determination means 54 that determines whether or not the power consumption is larger than the surplus power, and the power consumption Is larger than the surplus power, the heating period of the heating heaters 11 and 12 is switched depending on the size of the recording material 9 and the overlapping period shortening means 55 for shortening the overlapping period in which the heating heaters 11 and 12 are overlapped. Refer to priority switching means 56, priority setting means 57 for arbitrarily setting the priority of heaters 11 and 12, mode selection means 58 for setting image quality priority mode or power saving mode, and operation amount correction tables A and B. The operation amount correction means 59 for correcting the operation amount of the heaters 11 and 12 and the upper limit of the ON operation period of the heaters 11 and 12 are set. Time setting means 60, is realized.

  In addition to the program 51, the ROM 22b stores a priority heater selection table 52 and operation amount correction tables A and B, which will be described later. Note that the program 51 is distributed in a state of being stored in a portable storage medium 28 such as a CD, a DVD, or a flash memory, and is installed in the ROM 22b from the drive device. Note that it may be downloaded from a terminal connected via a network and installed in the ROM 22b.

  Based on the above configuration, the on / off control of the heaters 11 and 12 by the control unit 22 will be described. FIG. 3 is a diagram illustrating an example of on / off control of the heaters 11 and 12 when the marginal power Watt_max is equal to or greater than a predetermined value.

When the surplus power Watt_max is greater than or equal to a predetermined value, the control unit 22 uses the on-operation periods of the two heaters 11 and 12 as a reference for the start end of the control cycle. For example, the control period is 1 second, and the calculation result of the operation amount by the temperature control unit 23 is 60%, 40%, 60%, 100% for the heater 11, and 60%, 30%, 100% for the heater 12. , 40%, the control unit 22 controls on / off of the switch circuit as follows. The predetermined value for determining whether or not the marginal power Watt_max is equal to or greater than a predetermined value is determined in advance from the power required by the device.
Heater 11: Control cycle 1 “600 milliseconds on then 400 milliseconds off”
Control cycle 2 “400 milliseconds off then 600 milliseconds off”
Control period 3 “600 ms on then 400 ms off”
Control cycle 4 "1000 milliseconds on"
Heater 12: Control cycle 1 "600 milliseconds on then 400 milliseconds off"
Control cycle 2 “300 ms on then 700 ms off”
Control cycle 3 "1000 milliseconds on"
Control cycle 4 "400 milliseconds off then 600 milliseconds off"
FIG. 4 is a diagram illustrating an example of on / off control of the heaters 11 and 12 when the marginal power Watt_max is less than a predetermined value. When the surplus power Watt_max is less than a predetermined value, the control unit 22 uses the start end of the control cycle for the heater with high priority (here, the heater 11) as a reference for the ON operation period, and the heater 12 with low priority has the control cycle. The end of is used as a reference for the ON operation period. Thereby, the overlap period when both the two heaters 11 and 12 become an ON operation period can be reduced.

For example, when the control cycle is 1 second and the operation amount calculation result by the temperature control unit 23 is the same as that in FIG. 3, the control unit 22 controls the on / off of the switch circuit as follows.
Heater 11: Control cycle 1 “600 milliseconds on then 400 milliseconds off”
Control cycle 2 “400 milliseconds off then 600 milliseconds off”
Control period 3 “600 ms on then 400 ms off”
Control cycle 4 "1000 milliseconds on"
Heater 12: Control cycle 1 “400 milliseconds off then 600 milliseconds on”
Control cycle 2 “700 ms off then 300 ms on”
Control cycle 3 "1000 milliseconds on"
Control cycle 4 "400 ms off after 600 ms off"
In FIG. 3, the overlap period in the four control cycles is 1900 milliseconds, whereas in FIG. 4, it is 1200 milliseconds, and the overlap period can be reduced by about 37% even when the operation amount calculation result by PID is the same. It will be.

  FIG. 5 is a flowchart of a procedure in which the control unit 22 controls the ON operation period of the heaters 11 and 12. The flowchart of FIG. 5 is repeatedly executed, for example, every control cycle.

  The control unit 22 acquires the operation amount calculated by the temperature control unit 23 by the PID, and detects the surplus power Watt_max from the power consumption detection device 24 (S10).

  Then, the control unit 22 determines whether or not the surplus power Watt_max is less than a predetermined value (S20). When it is not less than the predetermined value (No in S20), the control unit 22 sets the start end of the control cycle for the two heaters 11 and 12 as a reference for the ON operation period (S30).

  When it is less than the predetermined value (Yes in S20), the control unit 22 sets the end of the control cycle for the heater 12 with low priority as a reference for the on-operation period (S40).

  According to the present embodiment, when the surplus power Watt_max is sufficient, the temperature of the rotating rollers 13 and 14 can be controlled with high accuracy. When the power available to the fixing device 10 is small, such as during image reading, the priority is given. By switching to the end of the ON operation period of the heater 12 having a low value, power consumption can be reduced while minimizing a decrease in accuracy.

  When the end of the control cycle is used as a reference, the light extinction period is first generated, so if the control cycle is relatively long, the temperature follow-up performance is degraded. However, since the reference of the ON operation period of the heater 12 with low priority is set as the end. In addition, it is possible to minimize a decrease in temperature followability.

  In this embodiment, since the device power consumption is increased, the marginal power Watt_max is reduced, and the two heaters 11 and 12 are used within the power consumption when the power consumption is lower than the power used by the fixing device 10 (hereinafter referred to as power consumption). The fixing device 10 that controls on / off of the toner will be described.

  The power consumption is the power consumption of the fixing device 10 determined according to the ON operation period. When the operation amount is 100%, the heater 11 consumes Watt_A power, and the heater 12 consumes Watt_B power. When the on-operation period of the heater 11 is M% and the on-operation period of the heater 12 is N%, the used power calculating unit 53 calculates the used power Watt_idl as follows.

Power consumption Watt_idl = Watt_A × M / 100 + Watt_B × N / 100
For example, when Watt_A is 550 W, Watt_B is 750 W, the heater 11 has an ON operation period of 80%, and the heater 12 has an ON operation period of 70%, the power consumption Watt_idl is 965 W.

  When the surplus power Watt_max is lower than the used power Watt_idl, the ON operation period based on the PID calculation becomes difficult. Therefore, the determination unit 54 determines whether or not the surplus power Watt_max is lower than the used power Watt_idl. If the surplus power Watt_max <the used power Watt_idl, the overlapping period shortening unit 55 determines whether the heater 12 with the lower priority is used. By shortening the ON operation period, the power consumption of the fixing device 10 is suppressed within the marginal power Watt_max.

  Since the ON operation period of the heater 11 having a high priority is the same as that of the first embodiment regardless of the device power consumption, the ON operation period of the heater 12 is determined as follows.

The electric power P1 that can be used in the heater 12 with low priority is:
Electric power P1 = margin electric power Watt_max− (Watt_A × M / 100)
Therefore, the value obtained by dividing the power P1 by Watt_B is the ON operation period of the heater 12.

An example of calculation is shown. When the surplus power Watt_max is, for example, 860 W,
Electric power P1 = 860W-440W = 420W
420W / 750W = 0.56
Therefore, even if the operation amount of the heater 12 by PID is 70%, the power consumption can be suppressed within the usable power usable in the fixing device 10 by reducing this to 56%.

  FIG. 6 is a diagram illustrating an example of on / off control of the heaters 11 and 12 when the surplus power Watt_max is lower than the used power Watt_idl. The control of the heater 11 having a high priority is the same as in the practical example 1. Further, in the case where the marginal power Watt_max <used power Watt_idl ≦ predetermined value, the heater 12 having a low priority is controlled based on the end of the control cycle as the reference for the ON operation period, as in the first embodiment.

  In this embodiment, the ON operation period of the heater 12 having a low priority is further shortened as shown in the above calculation example. For example, the control cycle is 1 second, and the calculation result of the operation amount by the temperature control unit 23 is 80%, 40%, 60%, 100% for the heater 11, and 70%, 30%, 100% for the heater 12. When it is 40%, the control unit 22 controls on / off of the switch circuit as follows. In FIG. 6, the surplus power Watt_max is set to 860 W.

  The control unit 22 detects the surplus power Watt_max for each control cycle, and the used power calculation unit 53 calculates the used power Watt_idl, and the determination unit 54 determines whether or not the surplus power Watt_max <used power Watt_idl. .

  Since the power consumption Watt_idl in the control cycles 1 to 4 is 965, 445, 1080, and 850 W, respectively, the surplus power Watt_max (860 W) is exceeded in the control cycles 1 and 3.

  Therefore, the overlapping period shortening means 55 shortens the ON operation period of the heater 12 in the control cycles 1 and 3. In the control cycle 1, 56% is the on operation period as described above, and in the control cycle 3, (860−330) / 750 = about 0.7 to 30% is the on operation period. Thus, by shortening the ON operation period of the heater 12 with low priority so as to be within the marginal power Watt_max, the marginal power Watt_max can be maximized to achieve both temperature follow-up and power saving. .

  FIG. 7 is a flowchart of a procedure in which the control unit 22 controls the ON operation period of the heaters 11 and 12. The flowchart in FIG. 7 is repeatedly executed, for example, every control cycle.

  The control unit 22 acquires the operation amount calculated by the temperature control unit 23 by the PID, and detects the surplus power Watt_max from the power consumption detection device 24 (S10).

  Then, the control unit 22 determines whether or not the surplus power Watt_max is less than a predetermined value (S20). When it is not less than the predetermined value (No in S20), the control unit 22 sets the start end of the control cycle for the two heaters 11 and 12 as a reference for the ON operation period (S30).

  When it is less than the predetermined value (Yes in S20), the used power calculation means 53 calculates the used power Watt_idl from the operation amount of the PID calculation result (S21). And the determination means 54 determines whether surplus electric power Watt_max <used electric power Watt_idl (S22). If the surplus power Watt_max is equal to or greater than the used power Watt_idl (No in S22), it is not necessary to shorten the on-operation period of the heater 12, so the control unit 22 ends the control cycle for the heater 12 with low priority. The on-operation period is used as a reference (S40).

  In the case of surplus power Watt_max <used power Watt_idl (Yes in S22), if the operation amount of the PID calculation is set to the on-operation period, the surplus power Watt_max is exceeded. The power consumption of the heater 11 is reduced, and the ON operation period of the heater 12 having a low priority is calculated from the value (S23).

  According to the present embodiment, in addition to the effects of the first embodiment, when the marginal power Watt_max is reduced because the device power consumption is during image formation or the like, the heater with a low priority is set so that the marginal power Watt_max is less than or equal to the marginal power Watt_max. Since the 12 on-operation periods are reduced, the overlap period can be reduced and the power consumption can be further reduced.

  In the first and second embodiments, the priority of the heaters 11 and 12 is fixed. However, which of the heaters 11 or 12 is prioritized is affected by the operating conditions of the image forming apparatus. The operating conditions are various conditions that can be set in the image forming apparatus at the time of printing, such as the fixing process time (continuous time of the fixing process), the size of the recording material 9, the presence / absence of double-sided printing, the presence / absence of color printing, and reduction / enlargement. is there. For example, the entire fixing device 10 is uniformly warmed when the image forming apparatus is started up, but priority is given to fixability during the fixing process. It is also known that the temperature distribution of the recording material 9 varies depending on the fixing process time.

  Therefore, in this embodiment, the priority of the heaters 11 and 12 is switched according to the operating conditions of the image forming apparatus such as standby, energy saving mode, fixing process time, and paper size.

  The ROM 22b of the control unit 22 stores a priority heater selection table 52 in which such operation conditions are associated with the heaters 11 or 12 to be prioritized. The priority switching means 56 refers to the priority heater selection table 52 based on the operation conditions input from the input device 27 such as the keyboard 27a and the touch panel 27b and other operation conditions, and prioritizes either the heater 11 or 12. Switch between high and low degrees. When the image forming apparatus receives a print request from a terminal connected via a network, the operation conditions are transmitted together with the print data.

  FIG. 8 shows an example of the priority heater selection table 52. For example, in the priority heater selection table 52, when the size of the recording material 9 is less than B4 (A4 or less), the priority of the heater 11 is higher than that of the heater 12, and the size of the recording material 9 is B4 or more. The priority of the heater 12 is set to be higher than that of the heater 11. In this way, by making the priority of the heater 11 or 12 variable according to the operating conditions, it is possible to easily realize suitable temperature followability for each operating condition. Although the size of the recording material 9 has been described according to the standard, specifically, it is preferable to determine the size based on the length of the recording material 9 passing through the rotation rollers 13 and 14 in the rotation direction. This is because the amount of heat taken from the rotating rollers 13 and 14 varies depending on the length of passage. Note that the size may be determined by the area of the recording material 9.

  FIG. 9 is a diagram illustrating an example of on / off control of the heaters 11 and 12 when the marginal power Watt_max is less than a predetermined value. This embodiment can be applied to both the first and second embodiments. FIG. 9 shows a case where the size of the recording material 9 is B4 or more, for example, and the priority of the heater 12 is higher than that of the heater 11. In such a case, when the surplus power Watt_max becomes less than a predetermined value, the heater 11 having a low priority is controlled to be turned on / off with the end of the control cycle as a reference for the on operation period.

For this reason, the heater 11 with low priority is on / off controlled as follows.
Heater 11: Control cycle 1 “400 ms off then 600 ms on”
Control cycle 2 “700 ms off then 300 ms on”
Control cycle 3 "1000 milliseconds on"
Control cycle 4 "400 ms off after 600 ms off"
FIG. 10 is a flowchart illustrating a procedure in which the control unit 22 controls the on-operation period of the heaters 11 and 12. The flowchart of FIG. 10 is repeatedly executed for each control cycle, for example.

  The priority switching means 56 refers to the priority heater selection table 52 based on the operating conditions, and switches the priority of the heaters 11 and 12 (S5). Note that since the operating condition is not changed in, for example, printing of a single sheet or a plurality of continuous sheets, the priority of the heaters 11 and 12 may be determined only when the operating condition is changed. The subsequent processing is the same as in the first embodiment. Also when applied to the second embodiment, step S5 may be processed before step S10.

  The control unit 22 acquires the operation amount calculated by the temperature control unit 23 by the PID, and detects the surplus power Watt_max from the power consumption detection device 24 (S10).

  Then, the control unit 22 determines whether or not the surplus power Watt_max is less than a predetermined value (S20). When it is not less than the predetermined value (No in S20), the control unit 22 sets the start end of the control cycle for the two heaters 11 and 12 as a reference for the ON operation period (S30).

  When it is less than the predetermined value (Yes in S20), the control unit 22 sets the end of the control cycle for the heater 12 with low priority as a reference for the on-operation period (S40).

  According to the present embodiment, in addition to the effects of the first and second embodiments, the priority of the heaters 11 and 12 can be made variable according to the operating conditions. Can be improved.

  Although it is preferable to reduce power consumption, there are cases where priority is given to improving image quality over reduction of power consumption. When such a user's determination is made, it is preferable to execute temperature control with priority on image quality in preference to the control of the fixing device 10 described in the first to third embodiments. Therefore, in this embodiment, when the user inputs a setting that prioritizes image quality from the input device 27, both the heaters 11 and 12 turn on the rear end of the control cycle even if the marginal power Watt_max is less than a predetermined value. The temperature of the rotating rollers 13 and 14 is controlled without using the operation period as a reference.

  FIG. 11 shows an example of an image quality setting screen displayed on the display. The mode selection means 58 displays the screen of FIG. 11 on the display 27b in response to a user's predetermined operation, and the user can select “normal printing” and “image quality priority”. When “image quality priority” is selected, the image forming apparatus forms an image in, for example, an image quality priority mode, and when “normal printing” is selected, for example, an image is formed in a power saving mode.

  When the user selects “image quality priority”, the control unit 22 fixes the heaters 11 and 12 to the reference of the ON operation period at the beginning of the control cycle even if the surplus power Watt_max is less than a predetermined value.

  Since “normal printing” is selected by default, the heater 11 or 12 having a low priority is placed after the control cycle if the marginal power Watt_max is less than a predetermined value unless the user selects “image quality priority”. The temperature is controlled with the end as a reference for the ON operation period.

  Accordingly, when the user selects “image quality priority”, both of the heaters 11 and 12 are used even when the marginal power Watt_max is less than the predetermined value as in the case where the marginal power Watt_max shown in FIG. On / off control is performed using the start end of the control cycle as a reference for the on-operation period. In addition, a present Example is applicable to any of Examples 1-3.

  Further, instead of selecting through “image quality”, it may be possible to directly select or input which of the heaters 11 or 12 is preferentially heated. The priority setting means 57 displays the arrangement of the heaters 11 and 12 on the display 27b with an illustration or the like, and sets the heater 11 or 12 arbitrarily selected by the user as a heater that preferentially heats.

  FIG. 12 is a flowchart of a procedure in which the control unit 22 controls the ON operation period of the heaters 11 and 12. The flowchart of FIG. 12 is repeatedly executed for each control cycle, for example.

  The priority setting unit 57 determines whether or not the image quality priority is input from the user (S4). When there is an input for priority on image quality (Yes in S4), the priority setting means 57 notifies the control unit 22 of this, and the control unit 22 controls the heaters 11 and 12 even if the surplus power Watt_max is less than a predetermined value. In either case, since the rear end of the control cycle is not used as a reference for the ON operation period, the process proceeds to step S30.

  When there is no image quality priority input (No in S4), the subsequent processing is the same as in the first embodiment. When applied to the third embodiment, step S4 may be set before step S5.

  The control unit 22 acquires the operation amount calculated by the temperature control unit 23 by the PID, and detects the surplus power Watt_max from the power consumption detection device 24 (S10).

  Then, the control unit 22 determines whether or not the surplus power Watt_max is less than a predetermined value (S20). When it is not less than the predetermined value (No in S20), the control unit 22 sets the start end of the control cycle for the two heaters 11 and 12 as a reference for the ON operation period (S30).

  When it is less than the predetermined value (Yes in S20), the control unit 22 sets the end of the control cycle for the heater 12 with low priority as a reference for the on-operation period (S40).

  According to the present embodiment, when the user wants to prioritize image quality, both the heaters 11 and 12 use the start end of the control cycle as a reference for the on-operation period even if the marginal power Watt_max is less than a predetermined value. It is possible to prioritize image quality by realizing high temperature tracking.

  Although the desired temperature accuracy may be obtained by calculating the operation amount by the PID calculation, in actual printing by the image forming apparatus, even if the rotation rollers 13 and 14 have reached the target temperature, the temperature drops at the beginning of paper feeding. In such a case, it may be preferable to make the ON operation period slightly longer than the operation amount based on the PID calculation result. Here, it is detected that the sheet is in the initial stage based on the fixing process time (for example, continuous printing time).

  In addition, if the size of the recording material 9 is small, the recording material 9 passes while leaving a range in which the heaters 11 and 12 are temperature-controlled. Therefore, an extreme temperature rise may occur in a portion where the recording material 9 does not pass. In such a case, it may be preferable to slightly shorten the ON operation period rather than the operation amount based on the PID calculation result.

  In this embodiment, a fixing device 10 is described in which the ON operation period of the two heaters 11 and 12 is variable depending on the fixing process time and the size of the recording material 9.

  FIG. 13A shows an example of an operation amount correction table A showing the relationship between the fixing process time and the operation amount correction amount for each of the heaters 11 and 12, and FIG. 13B shows correction of the paper size and the operation amount. An example of the operation amount correction table B indicating the relationship between the amounts will be shown.

  FIG. 13A shows the amount of correction of the operation amount of the heaters 11 and 12 according to the fixing process time tn (n: 1 to 3). For example, the operation amount of the heater 11 is 0 to t1 seconds. Is + 15% of the PID calculation result, is + 10% from t1 to t2, is + 5% from t2 to t3, and is not corrected after t3. The operation amount correction means 59 refers to the operation amount correction table A based on the fixing process time, and corrects the calculation results (operation amounts) of the heaters 11 and 12.

  As described above, the longer the fixing process time, the longer the operation amount of the heaters 11 and 12 is corrected, thereby preventing the temperature drop at the initial stage of paper passing. Although FIG. 13A shows a case where the operation amount is made longer, the operation amount may be corrected so as to be shortened when the fixing process time is long.

  FIG. 13B shows a correction amount of the operation amount of the heaters 11 and 12 according to the size of the recording material 9. For example, when the size is small (for example, B5 or less), the operation amount of the heater 11 is shown. It is shown that correcting -20% from the calculation result of PID does not correct the calculation result of PID when the size is large.

  The operation amount correction means 59 refers to the operation amount correction table B based on the size of the recording material 9 and corrects the calculation results (operation amounts) of the heaters 11 and 12.

  As described above, when the size is small, by correcting the operation amount of the heaters 11 and 12 to be shortened, it is possible to prevent an extreme temperature rise in a portion where the recording material 9 does not pass. Although FIG. 13B shows a case where the operation amount is shortened, the operation amount may be corrected to be longer when the size is small, or the operation amount may be corrected for each size.

  In FIGS. 13A and 13B, the operation amount is corrected based on the fixing process time and the size of the recording material 9, but the operation amount is corrected by linearly combining (adding) the respective correction amounts. Also good.

  Further, as shown in FIG. 13C, an upper limit value of the ON operation period may be set in the fixing process time. In FIG. 13C, the upper limit of the ON operation period of the heater 11 is set to 80% at 0 to t1 seconds, 70% is set to the upper limit at t1 to t2 seconds, and 60% is set at t2 to t3. It is shown that the upper limit is 50% at t3 to 50%. When the operation amount by the PID calculation exceeds these upper limits, the ON operation period is limited to the upper limit value, so that the followability to the target temperature can be maintained even with power saving. The paper size can be determined in the same manner.

  FIG. 14 is a diagram illustrating an example of on / off control of the heaters 11 and 12 when the marginal power Watt_max is less than a predetermined value. This embodiment can be applied to all embodiments.

  For example, when the fixing process time is t2 to t3, the calculation result of the operation amount by the temperature control unit 23 is 60%, 40%, 60%, 100% for the heater 11, and 60% for the heater 12. , 30%, 100%, 40%, the operation amount correction means 59 corrects the operation amount as follows.

Heater 11: 65%, 45%, 65%, 100%
Heater 12: 65%, 35%, 100%, 45%
Even if the marginal power Watt_max is less than or equal to a predetermined value, depending on the fixing process time, the amount of operation of the heaters 11 and 12 is corrected to be longer so that the followability of the target temperature is kept good while suppressing an increase in the overlap period. Will be able to. In addition, when the paper size is small, the amount of operation of the heaters 11 and 12 is corrected to be shortened, so that the increase in the overlapping period can be further reduced and the target temperature followability can be kept good.

  FIG. 15 is a flowchart of a procedure in which the control unit 22 controls the ON operation period of the heaters 11 and 12. The flowchart of FIG. 15 is repeatedly executed, for example, every control cycle.

  The control unit 22 acquires the operation amount calculated by the temperature control unit 23 by the PID, and detects the surplus power Watt_max from the power consumption detection device 24 (S10).

  Then, the control unit 22 determines whether or not the surplus power Watt_max is less than a predetermined value (S20). When it is not less than the predetermined value (No in S20), the control unit 22 sets the start end of the control cycle for the two heaters 11 and 12 as a reference for the ON operation period (S30).

  If it is less than the predetermined value (Yes in S20), the operation amount correction means 59 refers to the operation amount correction tables A and B according to the fixing process time and the paper size, and extracts the correction amount (S24). Then, the control unit 22 determines the on-operation period for the two heaters 11 and 12 using the corrected operation amount of the PID calculation, and sets the end of the control cycle as the on-operation period for the heater 12 with low priority. (S41).

  According to the present embodiment, in addition to the effects of the first to fourth embodiments, the followability of the target temperature can be kept good and the image quality can be improved regardless of the fixing process time and the paper size.

  By the way, an upper limit may be set for the on-operation period of the heaters 11 and 12. As described so far, the ON operation period is 100% at the maximum, but the heater 12 having a low priority can be set so that the PID calculation result is, for example, 70% as an upper limit. When the user's predetermined operation is input, the upper limit time setting means 60 displays a screen for setting an upper limit value for each of the heaters 11 and 12 on the display 27b, and the numerical value input by the user from the keyboard 27a is turned on. The upper limit of.

  For example, when the power situation of the use environment is getting worse, if the upper limit of the heaters 11 and 12 is 50%, the overlapping period can be always reduced to zero, so that power consumption can be reduced. Further, if a desired upper limit is set, temperature followability and toner image fixability can be finely adjusted.

  When the image forming apparatus is not used for a predetermined time for power saving, the image forming apparatus shifts to a standby state. In this standby state, however, accuracy is not required for temperature followability unlike the fixing process. Therefore, during standby, it is preferable to control the temperature by giving priority to power consumption over temperature followability. Therefore, in this embodiment, the fixing device 10 that controls the on-operation period of the heaters 11 and 12 so as to completely eliminate the overlapping period in the standby state will be described.

  FIG. 16 is a diagram illustrating an example of on / off control of the heaters 11 and 12 when the marginal power Watt_max is equal to or less than a predetermined value. When the calculation result of the operation amount by the temperature control unit 23 is 80%, 40%, 60%, 100% for the heater 11, and 70%, 30%, 100%, 40% for the heater 12, the control unit 22 shortens the operation amount of the heater 12 having a low priority so that the overlapping period becomes zero.

  In the control cycle 1, there is an overlap in the period of 50%, so 70-50 = 20% is the ON operation period of the heater 12, and in the control cycle 2, there is no overlap period, so the ON operation period of the heater 12 is shortened. However, in the control cycle 3, since it overlaps in the period of 60%, 100-60 = 40% is the ON operation period of the heater 12, and in the control cycle 4, it overlaps in the period of 40%, so 40-40 = 0% is the ON operation period of the heater 12.

  Thus, when a system is not required for temperature followability, the power consumption can be further reduced by controlling so that the plurality of heaters 11 and 12 are not turned on at the same time. The fixing device 10 of the present embodiment can be applied to all the embodiments of the first to fifth embodiments.

  In FIG. 16, the ON operation period of the heater 12 with low priority is shortened, but the ON operation periods of the two heaters 11 and 12 may be shortened regardless of the priority. For example, when the on-operation period is shortened by the same time for the two heaters 11 and 12, since 50% overlaps in the control period 1, 50/2 = 25% is subtracted, respectively. The ON operation period is 80-25 = 55%, and the ON operation period of the heater 12 is 70-25 = 45%. In the control cycle 3, since it overlaps in the period of 60%, 60/2 = 30% is subtracted, the ON operation period of the heater 11 is 60-30 = 30%, and the ON operation period of the heater 12 is 100%. −30 = 70% is the ON operation period. In the control cycle 4, since it overlaps in the period of 40%, 40/2 = 20% is subtracted, respectively, the ON operation period of the heater 11 is 100-20 = 80%, and the ON operation period of the heater 12 is 40%. −20 = 20% is the on-operation period. Further, a shortening ratio (for example, a shortening ratio 3 for the heater 11 with a high priority and a shortening ratio 7 for the heater 12 with a low priority) is determined according to the priority, and two heaters are set according to the shortening ratio. Each of the on-operation periods 11 and 12 may be shortened.

  FIG. 17 is a flowchart illustrating a procedure in which the control unit 22 controls the on-operation period of the heaters 11 and 12. The flowchart of FIG. 17 is repeatedly executed, for example, every control cycle.

  The control unit 22 acquires the operation amount calculated by the temperature control unit 23 by the PID, and detects the surplus power Watt_max from the power consumption detection device 24 (S10).

  Then, the control unit 22 determines whether or not the surplus power Watt_max is less than a predetermined value (S20). When it is not less than the predetermined value (No in S20), the control unit 22 sets the start end of the control cycle for the two heaters 11 and 12 as a reference for the ON operation period (S30).

  When it is less than the predetermined value (Yes in S20), the control unit 22 determines whether or not the total operation amount of the two heaters 11 and 12 by the PID calculation exceeds 100% (S42). When it does not exceed 100% (No in S42), the end of the control cycle is set as the reference for the on-operation period for the heater 12 with low priority as in the first embodiment (S40).

  When it exceeds 100% (Yes in S42), the control unit 22 determines whether or not the image forming apparatus is in a standby state (S43). If it is not in the standby state (No in S43), it is not preferable to impair the temperature followability, so the process proceeds to step S40, and the end of the control cycle is set to the end of the on operation period for the heater 12 having a low priority without shortening the on operation period. A reference is made (S40).

  In the standby state (Yes in S43), the control unit 22 subtracts the operation amount exceeding 100% from the ON operation period of either the heater 11 or 12 (S44). Thereby, in the standby state, reduction of power consumption can be prioritized over temperature followability. In addition, when applying a present Example to Example 2, what is necessary is just to perform the process after step S42 after step S23.

  According to the present embodiment, when a system is not required for temperature followability, the power consumption can be further reduced by controlling so that the plurality of heaters 11 and 12 are not turned on at the same time.

[Image forming apparatus]
An image forming apparatus to which the fixing device 10 of this embodiment is applied will be described.
FIG. 18 is a schematic configuration diagram of an image forming apparatus 100 in which the fixing device 10 is applied to an electrophotographic copying machine, a printer device, or the like. The image forming apparatus 100 is largely divided into a reading unit 32 for reading a document, an image forming unit 41 for forming an image, an automatic document feeder (ADF) 67, a document discharge tray 63 for stacking documents sent from the ADF 67, a paper feed cassette. The sheet feeding unit 39 includes 35 to 38, and a sheet discharge unit (sheet discharge tray 33) for stacking recording sheets.

  When the document D is set on the document table 66 of the ADF 67 and an operation on the input device 27 (not shown), for example, a print key is pressed, the uppermost document D is sent in the direction of the arrow B1 by the rotation of the pickup roller 68, and the document By the rotation of the conveyance belt 65, the sheet is fed onto the contact glass 64 fixed to the image reading unit 32, and stops there. The image of the recording material 9 placed on the contact glass 64 is read by the reading device 43 positioned between the image forming unit 41 and the contact glass 64. The reading device 43 includes a light source 31 that illuminates the document D on the contact glass 64, an optical system 62 that forms an image of the document, a photoelectric conversion element 61 that includes a CCD that forms an image of the document, and the like. After the image reading is completed, the document D is transported in the direction of the arrow B2 by the rotation of the document transport belt 65 and discharged onto the paper discharge tray 63. In this way, the document D is fed one by one onto the contact glass 64 and the document image is read by the image reading unit 32.

  On the other hand, inside the image forming unit 41, a photoreceptor 44 as an image carrier is disposed. The photosensitive member 44 is driven to rotate clockwise in the drawing, and the surface is charged to a predetermined potential by the charging device 47. Further, the writing unit 49 emits a laser beam L that is light-modulated in accordance with image information read by the reading device 43, and the surface of the charged photosensitive member 44 is exposed with the laser beam L, whereby the photosensitive member is exposed. An electrostatic latent image is formed on the surface 44. When the electrostatic latent image passes through the developing device 42, the electrostatic latent image is transferred to the recording material 9 fed between the photosensitive member 44 and the transfer device 45 by the opposing transfer device 45. The surface of the photoreceptor 44 after the toner image is transferred is cleaned by a cleaning device 48.

  A plurality of paper feed cassettes 35 to 38 arranged at the lower part of the image forming unit 41 accommodate recording materials 9 such as paper, and the recording materials 9 are fed from any of the paper feed cassettes 35 to 38 in the direction of arrow B3. The toner image formed on the surface of the photoreceptor 44 as described above is transferred onto the surface of the recording material 9. Next, the recording material 9 is passed through the fixing device 10 in the image forming unit 41 as indicated by an arrow B4, and the toner image transferred to the surface of the recording material 9 by the action of heat and pressure is fixed. The recording material 9 that has passed through the fixing device 10 is conveyed by the discharge roller pair 34, discharged to the discharge tray 33 as indicated by an arrow B5, and stacked.

  Although FIG. 18 shows an image forming apparatus for monochrome printing such as monochrome printing, the fixing apparatus 10 of the present embodiment can be similarly applied to a color image forming apparatus. In the case of color printing, for example, toner images of four colors (cyan, magenta, yellow, black) are overlaid to form a color image. For this reason, after the four color toner images are transferred one after another from the photosensitive drum to the intermediate transfer member (belt or drum) in sequence, the four color toner images on the intermediate transfer member are collectively transferred to the recording material 9. Although the temperature and the like are different, fixing of the transferred unfixed image to the recording material 9 is the same as in the case of monochrome printing.

  The fixing device 10 of the present embodiment can be suitably applied as long as it is an electrophotographic image forming apparatus 100. In addition to a copying machine as shown in FIG. 18, the image forming apparatus 100 can be a printer, a facsimile, or an MFP (Multi Function Printer). Etc.

1 is a schematic configuration diagram of a fixing device mounted on an image forming apparatus. 1 is an example of a block diagram of a fixing device. It is a figure which shows an example of on / off control of two heaters when margin electric power is more than predetermined value. (Example 1) which is a figure which shows an example of on / off control of two heaters in case surplus electric power is less than predetermined. (Example 1) which is a flowchart of the procedure in which a control part controls the ON operation period of two heaters. (Example 2) which is a figure which shows an example of on / off control of a heater when the margin electric power Watt_max is less than the use electric power Watt_idl. (Example 2) which is a flowchart of the procedure in which a control part controls the ON operation period of two heaters. It is a figure which shows an example of a priority heater selection table. (Example 3) which is a figure which shows an example of on / off control of two heaters in case surplus electric power is less than predetermined. (Example 3) which is a flowchart of the procedure in which a control part controls the ON operation period of two heaters. It is a figure which shows an example of the setting screen of the image quality displayed on a display. (Example 4) which is a flowchart of the procedure in which a control part controls the ON operation period of two heaters. It is a figure which shows an example of operation amount correction table A and B which show the relationship between fixing process time or paper size, and the correction amount of the operation amount of two heaters. (Example 5) which is a figure which shows an example of on / off control of two heaters in case surplus electric power is less than predetermined. (Example 5) which is a flowchart of the procedure in which a control part controls the ON operation period of two heaters. (Example 6) which is a figure which shows an example of on / off control of two heaters in case margin electric power is below a predetermined value. (Example 6) which is a flowchart of the procedure in which a control part controls the ON operation period of two heaters. 1 is a schematic configuration diagram of an image forming apparatus in which a fixing device is applied to an electrophotographic copying machine, a printer device, or the like. It is a figure which shows an example of the conventional time proportional control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 Recording material 10 Fixing device 11,12 Heater 13,14 Rotating roller 15,16 Temperature sensor 21 Target temperature setting means 22 Control part 23 Temperature control part 24 Power consumption detection apparatus 25 Power supply circuit 26 AC power supply 27 Input device 28 Storage medium 51 Program 52 Priority Heater Selection Table 53 Power Use Calculation Unit 54 Judgment Unit 55 Duplicate Period Shortening Unit 56 Priority Switching Unit 57 Priority Setting Unit 58 Mode Selection Unit 59 Operation Amount Correction Unit 60 Upper Limit Time Setting Unit A, B Operation Amount Correction table

Claims (18)

In a fixing device mounted on a mounted device and fixing an unfixed image on a recording material to the recording material by heating by a plurality of heating units,
A calculation unit that independently calculates an operation amount of the plurality of heating units for each control period;
From the beginning of the control cycle, a control unit that independently controls energization of the plurality of heating units for an energization period according to the operation amount;
Surplus power detection means for detecting surplus power that can be used by the fixing device among the power that can be supplied by the mounted device, and
When the marginal power is less than a predetermined value, the control unit has the low priority so that the end of the energization period of the heating unit having a low priority is substantially coincident with the end of the control cycle. To control the energization
A fixing device. Power consumption calculating means for calculating power consumption consumed by the fixing device in a control cycle based on the operation amount;
Determining means for determining whether or not the used power is greater than the margin power;
When the power used is larger than the surplus power, an overlapping period shortening means for shortening an overlapping period in which a plurality of the heating units are energized and controlled, and
The fixing device according to claim 1, further comprising: The overlapping period shortening means shortens the energization time of the heating unit with the low priority to shorten the overlapping period,
The fixing device according to claim 2.   4. The fixing device according to claim 3, further comprising a priority switching unit configured to acquire a size of the recording material and switch the priority of the plurality of heating units according to the size. Priority heater selection table storage means for storing a priority heater selection table in which the priorities of the plurality of heating units are set in association with operating conditions such as when the mounted device is started up, during standby, and during a fixing process; ,
Priority switching means for referring to the priority heater selection table based on operating conditions and switching the priority of the plurality of heating units;
The fixing device according to claim 3, further comprising:   The fixing device according to claim 3, further comprising priority switching means for switching the priority of the plurality of heating units according to a fixing process time.   The fixing device according to claim 3, further comprising a priority setting unit configured to arbitrarily set the priority of the plurality of heating units. It has mode selection means for setting the image quality priority mode or the power saving mode,
When the image quality priority mode is selected,
The control unit performs energization control of the plurality of heating units independently for an energization period according to the operation amount from the start of the control cycle even when the marginal power is equal to or less than a predetermined value.
The fixing device according to claim 1, wherein An operation amount correction table storage unit that stores an operation amount correction table in which correction amounts of the operation amounts of the plurality of heating units are set in association with the fixing process time;
An operation amount correction means for referring to the operation amount correction table based on a fixing process time and correcting the operation amounts of the plurality of heating units;
The fixing device according to claim 1, further comprising: An operation amount correction table storage unit that stores an operation amount correction table in which correction amounts of the operation amounts of the plurality of heating units are set in association with the size of the recording material;
An operation amount correction means for correcting the operation amounts of the plurality of heating units with reference to the operation amount correction table based on the size of the recording material;
The fixing device according to claim 1, further comprising: An upper limit time setting means for setting an upper limit of the energization time of the plurality of heating units,
The control unit limits the energization period to the upper limit or less regardless of the operation amount calculated by the calculation unit.
The fixing device according to claim 1, wherein: When there is an overlap period in which a plurality of heating units are overlapped and energized and controlled, the control unit shortens the energization time of one or more of the heating units so that there is no overlap period.
The fixing device according to claim 1, wherein:   The fixing device according to claim 4, wherein the control unit determines the size of the recording material from a length of the recording material passing through the fixing device.   An image forming apparatus equipped with the fixing device according to claim 1. A photoreceptor, and an intermediate transfer body to which an unfixed image formed on the photoreceptor is transferred,
An unfixed image is transferred from the intermediate transfer member to the recording material, and the unfixed image is fixed to the recording material by the fixing device.
The image forming apparatus according to claim 14. A calculation unit that is mounted on the mounted device and independently calculates the operation amount of the plurality of heating units for each control cycle, and margin power detection means that detects usable margin power among the power supplied by the mounted device; In a temperature control method of a fixing device for fixing an unfixed image on a recording material to the recording material by heating the unfixed image on the recording material,
A step of determining whether or not the surplus power is less than a predetermined value;
If the marginal power is not less than a predetermined value, the control unit independently controls energization of the plurality of heating units for an energization period according to the operation amount from the start of the control cycle;
When the marginal power is less than a predetermined value, the control unit has a low priority so that the end of the energization period of the heating unit having a low priority is substantially coincident with the end of the control cycle. A step of energizing the heating unit;
A temperature control method for a fixing device. Installed in the mounted device to detect the operation power of multiple heating units independently for each control period so that the target temperature can be obtained, and to detect the surplus power available from the power supplied by the mounted device To the surplus power detecting means, and the computer connected to the
Determining whether the marginal power is less than a predetermined value;
When the marginal power is not less than a predetermined value, from the start of the control cycle, independently conducting energization control of the plurality of heating units for an energization period according to the operation amount; and
When the marginal power is less than a predetermined value, energization control is performed on the heating unit having a low priority so that the end of the energization period of the heating unit having a low priority is substantially coincident with the end of the control cycle. And steps to
A program characterized by having executed.   A computer-readable storage medium storing the program according to claim 17.

Images