JP2005215448A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption and prevent shutoff of a power source. <P>SOLUTION: The image forming apparatus includes: a heating body which heats a fixing roller; a temperature detecting part which detects the temperature of the fixing roller; a driving means for driving the heating body by turning on/off a drive signal in accordance with the turning on of the power source; and a duty altering means for altering the duty of the drive signal. Thus, since the heating body is intermittently driven with the specific duty according to the turning on of the power source, a current is made to flow in a heater intermittently. As a result, power consumption can be reduced and shutoff of the power source can be prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus.

  Conventionally, in an image forming apparatus such as an electrophotographic printer, a copying machine, a facsimile machine, etc., the surface of a photosensitive drum is uniformly and uniformly charged and exposed to form an electrostatic latent image. The electrostatic latent image is developed to form a toner image, and the toner image is transferred to a printing medium such as paper by a transfer roller. Then, the print medium on which the toner image is transferred is sent to the fixing device.

  The fixing device has a built-in heater as a heat source and is rotated, and similarly has a built-in heater, and is provided with a pressure roller that is pressed against and rotated by the fixing roller, to which a toner image is transferred. As the printed medium passes through the nip region formed between the fixing roller and the pressure roller, the toner image is heated and fused to the printing medium (see, for example, Patent Document 1). .)

  FIG. 2 is a time chart showing the operation of the conventional fixing device.

  In this case, a power source voltage of a commercial power source as a power source is applied to each heater, and when the heater lighting signal is turned on (low level), the heater current starts to flow. In addition, the target temperature of the fixing roller and the pressure roller is set by the sequence control unit, and the temperature detected by each thermistor disposed on the fixing roller and the pressure roller, that is, the detected temperature is set as the fixing possible temperature. Each heater is turned on via the fixing heater driver until the target temperature is reached, and when the rise time t1 has elapsed and the detected temperature reaches the target temperature, on / off control is performed and the target temperature is maintained. .

By the way, the heater has a low resistance because the temperature is low in the initial state where lighting is started. Therefore, as the heater lighting signal is turned on, an inrush current flows, and the amplitude of the heater current is first the largest and gradually decreases with time.
JP-A-8-314322

  However, in the conventional fixing device, if the inrush current is large, the power consumption increases correspondingly, and the commercial power supply may be cut off when other electrical devices are used simultaneously.

  An object of the present invention is to solve the problems of the conventional image forming apparatus, and to provide an image forming apparatus capable of reducing power consumption and preventing power from being cut off. .

  For this purpose, in the image forming apparatus of the present invention, a heating body for heating the fixing roller, a temperature detecting unit for detecting the temperature of the fixing roller, and a drive signal when the power is turned on. Drive processing means for driving the heating body by turning on and off, and duty change processing means for changing the duty of the drive signal.

  According to the present invention, in the image forming apparatus, the heating body that heats the fixing roller, the temperature detection unit that detects the temperature of the fixing roller, and the drive signal when the power is turned on. Drive processing means for driving the heating body by turning on and off, and duty change processing means for changing the duty of the drive signal.

  In this case, as the power is turned on, the heater is intermittently driven at a predetermined duty, so that the heater current can flow intermittently. Therefore, power consumption can be reduced and the power supply can be prevented from being shut off.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 3 is a sectional view of the fixing device according to the first embodiment of the present invention.

  In the figure, reference numeral 11 denotes a fixing device, in which a printing medium 18 such as a sheet on which a toner image 19 is transferred, an OHP sheet, and the like are added as a fixing roller 12 as a first fixing roller and a second fixing roller. The toner image 19 is fixed to the print medium 18 as it passes through the nip region formed between the pressure roller 15 and the pressure roller 15.

  The fixing roller 12 is provided with a heater 14 as a first heating body, an elastic layer 12b made of silicone rubber or the like formed on the surface of a core metal 12a made of metal such as iron, and the like. A release layer 12c made of a fluorine resin or the like is provided on the surface of the elastic layer 12b. The fixing roller 12 is rotatably disposed by a support member (not shown).

  The pressure roller 15 is urged against the fixing roller 12 by a spring 10 as an urging member and is brought into pressure contact with the fixing roller 12. Here, the pressure roller 15 is provided with a heater 17 as a second heating body, and an elastic layer made of silicone rubber or the like formed on the surface of a metal core 15a made of a metal pipe such as aluminum. 15b and a release layer 15c made of a fluororesin or the like, which is coated on the surface of the elastic layer 15b. The pressure roller 15 is rotatably disposed by a support member (not shown).

  A gear (not shown) is provided at one end of the fixing roller 12, and rotation is transmitted to the fixing roller 12 via a gear (not shown) provided in the main body of the image forming apparatus. Is rotated by being driven by.

  A thermistor 13 as a first temperature detector is disposed on the fixing roller 12, and a thermistor 16 as a second temperature detector is disposed on the pressure roller 15 so as to be in contact with a substantially central portion in the axial direction. . The thermistors 13 and 16 can also be arranged in a non-contact state. Accordingly, the temperatures of the fixing roller 12 and the pressure roller 15 are controlled by a control unit (not shown).

  FIG. 1 is a block diagram showing a control device of the image forming apparatus according to the first embodiment of the present invention.

  As shown in the figure, the image forming apparatus 20 is connected to a host computer 30 by an interface unit 29 and receives power from a commercial power source 35 as a power source. The electric power from the commercial power source 35 is converted to a predetermined voltage on the one hand by the low-voltage power supply unit 21 and connected to the fixing heater driver 22 on the other hand, and is supplied to the heaters 14 and 17 by the heater driving circuit 40. 14 and 17 are driven and turned on to generate heat.

  The low-voltage power supply unit 21 includes an interruption detection circuit 21a and a sub power supply circuit 21b. The shut-off detection circuit 21a monitors the voltage supplied from the commercial power source 35, that is, the input voltage and the on / off of a power switch (not shown), and the power switch is turned on / off so that the input voltage is a predetermined value. When the voltage is lower than the voltage, it is determined that the commercial power source 35 is turned off. Further, it is determined that the commercial power source 35 has been cut off when the input voltage becomes equal to or lower than a predetermined voltage without turning on / off the power switch.

  The sub power supply circuit 21b supplies low-voltage power to the sequence control unit 24 and the interruption detection circuit 21a in order to operate the sequence control unit 24 for a predetermined time when the commercial power supply 35 is turned off.

  The interruption detection circuit 21a instructs the sub power supply circuit 21b to supply power to the sequence control unit 24 as the input voltage becomes equal to or lower than a predetermined voltage. Thereby, the sub power supply circuit 21b supplies power to the sequence control unit 24 for a predetermined time, and the sequence control unit 24 performs a predetermined power-off sequence. When the sub power supply circuit 21b supplies power to the sequence control unit 24 for a predetermined time, the supply of power to the sequence control unit 24 is terminated and the sub power supply circuit 21b enters a power-off state.

  Further, when the interruption detection circuit 21a determines that the commercial power supply 35 has been interrupted, as described above, the interruption detection circuit 21a instructs the sequence control unit 24 to supply power for a predetermined time, and also to the sequence control unit 24. A notification that the commercial power source 35 is shut off is sent. When the sequence control unit 24 receives a notification that the commercial power supply 35 has been shut off from the shutoff detection circuit 21a, the sequence control unit 24 records the shutoff information indicating that the commercial power supply 35 has been shut down in a storage unit 24b including a memory such as an EEPROM. To do. When the power switch is turned on next time, the sequence control unit 24 detects whether or not the commercial power source 35 recorded in the storage unit 24b is cut off. Control for starting up the fixing device 11 (FIG. 3) is performed.

  The temperature of the fixing roller 12 is detected by the thermistor 13, and the temperature of the pressure roller 15 is detected by the thermistor 16 and sent to the sequence control unit 24. The temperature control unit 24 a as temperature control processing means of the sequence control unit 24 includes: Control is performed so that the temperatures of the fixing roller 12 and the pressure roller 15 become the target temperatures.

  The sequence control unit 24 includes the temperature control unit 24a, a storage unit 24b, a timer 24c, and the like, and the thermistors 13 and 16, a high voltage power supply unit 23, an optical system driver unit 25, a motor drive driver 26, an image processing unit 27, and an interface. Connected to the unit 29. Further, the sequence control unit 24 is connected to an operation panel 28 as an operation unit, and accepts settings from a user, displays a state, and the like on the operation panel 28.

  Furthermore, the sequence control unit 24 switches between two modes that can be selected in accordance with an input from the operation panel 28 or the host computer 30, and until the temperature of the fixing roller 12 and the pressure roller 15 reaches a certain target temperature. During the startup time, when the normal power mode is selected as the first supply mode in which the normal power consumption as the first energy is supplied and the heaters 14 and 17 are turned on, and the commercial power supply 35 is shut off. Control is performed by selecting the low power consumption mode as the second supply mode in which the heaters 14 and 17 are turned on with the small power consumption as the second energy.

  Next, the heater drive circuit 40 will be described.

  FIG. 4 is a block diagram showing a heater drive circuit according to the first embodiment of the present invention.

  As shown in the figure, the heater drive circuit 40 includes a drive element 41, a zero cross timing detection circuit 42, a noise filter 43, a CPU 44, and the like. The drive element 41 supplies power from the commercial power source 35 to the heaters 14 and 17. Supply. For this purpose, the zero-cross timing detection circuit 42 detects the timing at which the power supply voltage of the commercial power supply 35 passes the zero (0) point, and sends a zero-cross signal to the CPU 44. Upon receiving the zero cross signal, the CPU 44 outputs a heater lighting signal as a drive signal to the drive element 41. The heaters 14 and 17 are turned on according to the heater lighting signal, and the temperatures of the fixing roller 12 and the pressure roller 15 are gradually increased.

  Next, the operation of the image forming apparatus 20 (FIG. 1) configured as described above will be described.

  FIG. 5 is a flowchart showing the operation of the image forming apparatus according to the first embodiment of the present invention.

  First, it waits for the power switch to be turned on, and when the power switch is turned on, a block information determination processing unit (not shown) of the sequence control unit 24 (FIG. 1) performs a block information determination process, Reference is made to 24b to determine whether the storage unit 24b has blocking information. When there is cutoff information, a mode selection processing unit (not shown) of the sequence control unit 24 performs mode selection processing to select a low power consumption mode. When there is no cutoff information, the mode selection processing unit selects the normal power mode. select.

  Subsequently, the temperature control unit 24a performs temperature control processing in a mode selected via the fixing heater driver 22, waits for the fixing set temperature to be reached, and displays the printable state when the fixing set temperature is reached. Then, the process shifts to a standby state, and the process ends.

Next, a flowchart will be described.
Step S1 Wait for the power switch to be turned on, and if the power switch is turned on, the process proceeds to step S2.
Step S2: Refer to the storage unit 24b.
Step S3: It is determined whether there is blocking information. If there is blocking information, the process proceeds to step S4. If there is no blocking information, the process proceeds to step S5.
Step S4: The low power consumption mode is selected.
Step S5: Select the normal power mode.
Step S6: Start the temperature control process in the selected mode.
Step S7 Wait until the fixing set temperature is reached. If the fixing set temperature is reached, the process proceeds to Step S8.
Step S8: The printable state is displayed, the process shifts to the standby state, and the process ends.

  In the present embodiment, on / off control of the heaters 14 and 17 is performed in order to reduce the current value when the power is turned on compared to the current state.

  Next, the operation of the temperature control process when the normal power mode is selected will be described.

  FIG. 6 is a first time chart showing the operation of the temperature control process when the normal power mode is selected in the first embodiment of the present invention, and FIG. 7 is the normal power in the first embodiment of the present invention. It is a 2nd time chart which shows the detailed operation | movement of the temperature control process when a mode is selected.

  First, when the zero-cross timing detection circuit 42 (FIG. 4) detects that the power supply voltage of the commercial power source 35 has passed the zero point and sends a zero-cross signal to the CPU 44, the drive processing means (not shown) of the CPU 44 includes the temperature control unit. When the driving process is performed based on the instruction by 24a and the commercial power supply 35 is turned on, when the on a1 of the zero cross signal on (low level) ai (i = 1, 2,...) Is detected, The heaters 14 and 17 are turned on by turning on and off the heater lighting signal. For this purpose, the drive processing means starts timing of a first timer built in the CPU 44, and when a predetermined time tfj (j = 1, 2,...) Elapses, the heater lighting signal is turned on (low level). To. Then, as the heater lighting signal is turned on, the drive processing means starts measuring a second timer built in the CPU 44, and when a predetermined time toj (j = 1, 2,...) Elapses, the heater Turn off the lighting signal (high level). In this way, the heater lighting signal is repeatedly turned on and off.

The times tfj and toj and the number of times the heater lighting signal is turned on / off are obtained in advance by experiments and recorded in the storage unit 24b (FIG. 1). Each time tfj, toj is
tf1>tf2> tf3 ...
to1 <to2 <to3 ...
It is set so that Sum of times tfj and toj, that is, on / off cycle T of the heater lighting signal
T = tfj + toj
Is made constant.

  When the heater lighting signal is repeatedly turned on and off for a predetermined number of repetitions, the heater lighting signal remains on and the temperatures of the fixing roller 12 and the pressure roller 15 are increased.

  In the present embodiment, when the zero cross signal ON a1 is detected, the time tfj and toj are measured repeatedly. However, each time the zero cross signal is turned on ai, the time tfj is started to be measured. In the meantime, the heater lighting signal can be turned on, and then the heater lighting signal can be turned off. In that case, the time toj is not counted.

  Since the heater current flows much when the temperature of the heaters 14 and 17 is low, the temperature of the heaters 14 and 17 becomes a predetermined temperature, the time for which the heater current is stabilized is obtained by experiment, and the time when the heater current is stabilized is obtained. Based on this, the number of repetitions is set.

  Thus, as the commercial power supply 35 is turned on, the heater lighting signal is turned on / off while the temperature of the heaters 14 and 17 is low, and the heaters 14 and 17 are intermittently driven at a predetermined duty. , The heater current can be intermittently supplied. Therefore, power consumption can be reduced and the commercial power supply 35 can be prevented from being shut off.

  Further, since the heater current flows after the time tfi has elapsed from the zero crossing timing, the inrush current I2 can be reduced. The rise time t2 at which the detected temperature becomes the target temperature is longer than the rise time t1 in the conventional image forming apparatus.

  Next, the operation of the temperature control process when the low power consumption mode is selected will be described.

  FIG. 8 is a time chart showing the operation of the temperature control process when the low power consumption mode is selected in the first embodiment of the present invention.

  In this case, the duty change processing means as the heating body drive processing means (not shown) of the CPU 44 (FIG. 4) performs the duty change processing as the heating body drive processing, and the duty of the heater lighting signal corresponding to the selected mode, In the present embodiment, the heaters 14 and 17 are driven by changing the on-duty representing the on-time. That is, when the low power consumption mode is selected, the duty change processing means makes the on-duty smaller than when the normal power mode is selected. Therefore, the inrush current I3 becomes smaller than the inrush current I2 (FIG. 7). The rise time t3 when the low power consumption mode is selected is longer than the rise time t2. In the present embodiment, the temperature control process is performed by changing the duty of the heater lighting signal. However, the temperature control process is performed by changing the electric power supplied to the heaters 14 and 17. It can also be done.

  By the way, the respective modes can be selected by the operator operating the operation panel 28 (FIG. 1).

  In that case, when the operator first turns on the power switch while pressing a predetermined key (not shown) on the operation panel 28, each mode can be selected, and the display processing means (not shown) of the sequence control unit 24 is displayed. The display processing is performed, and a display panel (not shown) serving as a display unit is prompted to press a predetermined X key when selecting the normal power mode and a predetermined Y key when selecting the low power consumption mode. Display a message. Therefore, when the operator presses the X key or the Y key, the mode selection processing means selects a mode, and a mode recording processing means (not shown) of the sequence control unit 24 performs mode recording processing, and selects the selected mode. It is recorded in the storage unit 24b.

  Subsequently, the temperature control unit 24a performs temperature control processing in the selected mode, waits for reaching the fixing set temperature, and when reaching the fixing set temperature, displays the printable state and shifts to the standby state. Then, the process ends.

  Since the selected mode is recorded in the storage unit 24b, when the power switch is turned on next time, the temperature control unit 24a refers to the storage unit 24b, reads the selected mode, and is selected. Control the temperature in the selected mode. The mode recorded in the storage unit 24b is not changed until the operator selects the mode again.

  By the way, in the present embodiment, when the low power consumption mode is selected, the start-up time t3 becomes long, and when there is a margin in power consumption, the printable state is unnecessarily delayed. .

  Therefore, instead of selecting a mode, a second embodiment of the present invention will be described in which the fixing temperature is raised based on the startup time when the operator inputs a predetermined startup time. To do. The structure of the image forming apparatus in the present embodiment is the same as that in the first embodiment, and will be described with reference to FIGS.

  FIG. 9 is a flowchart showing the operation of the image forming apparatus in the second embodiment of the present invention, and FIG. 10 is a diagram showing an on-duty table in the second embodiment of the present invention.

In the present embodiment, the operator can input and set the rise time Tk (k = 1, 2,...) By performing a specific operation on the host computer 30 (FIG. 1). It has become. Further, an on-duty table shown in FIG. 10 is recorded in a storage unit (not shown) built in the CPU 44 as a memory, and the on-duty table shows an on-time representing the rise time Tk and the first on-time of the heater lighting signal. Duty xk (k = 1, 2,...), Addition value Δxk (k = 1, 2,...), Number of repetitions yk (k = 1, 2,...), Etc. are recorded in association with each other. The rise time Tk and on-duty xk are obtained in advance by experiments,
T1 = 1 [minute]
T2 = 2 [minutes]
T3 = 3 [minutes]
T4 = 4 [minutes]
...
When
x1>x2>x3> x4 ...
It is set so that The on-duty xk is shortened as the rise time Tk is longer. The added value Δxk is sequentially added to each on-duty xk,
x (k + 1) ← xk + Δxk
And the number of repetitions yk is the number of times the heater lighting signal is turned on repeatedly.

  In this case, it waits for the power switch to be turned on, and when the power switch is turned on, the temperature control unit 24a as the temperature control processing means determines whether or not the rise time Tk is set. When the rise time Tk is set, the duty change processing means changes the on-duty xk according to the rise time Tk, and the temperature control process is performed based on the on-duty xk, the added value Δxk, and the number of repetitions yk. I do. The drive processing means of the CPU 44 reads the on-duty xk, the added value Δxk, and the number of repetitions yk corresponding to the rise time Tk set based on the instruction from the temperature control unit 24a, and the on-duty xk, The heater lighting signal is turned on / off based on the added value Δxk and the number of repetitions yk, and the heaters 14 and 17 as the first and second heating bodies are turned on.

  In the present embodiment, the on-duty xk can be calculated by repeatedly adding the addition value Δxk by the number of repetitions yk, but all the on-duty xk are recorded as a table. You can also

  Thus, since the operator can arbitrarily set the rise time Tk, it is possible to prevent the printable state from being unnecessarily delayed when there is a sufficient power consumption.

Next, a flowchart will be described.
Step S11 The system waits for the power switch to be turned on, and proceeds to step S12 when the power switch is turned on.
Step S12 Wait until the rise time Tk is set, and when the rise time Tk is set, the process proceeds to step S13.
Step S13 The temperature control process is started according to the rise time Tk.
Step S14 Wait for the fixing set temperature to be reached, and if the fixing set temperature is reached, proceed to Step S15.
Step S16: The printable state is displayed, the process shifts to the standby state, and the process ends.

  In this embodiment, the heater lighting signal is turned on / off for the number of repetitions yk. However, the heater lighting signal is turned on / off only when the detected temperature is low, and the detected temperature is high. When the heater current is small, it can be always turned on.

  In this embodiment, the on-duty xk, the added value Δxk, and the number of repetitions yk are set in correspondence with the rise time Tk. However, instead of the rise time Tk, power consumption is set. The on-duty xk, the added value Δxk, and the number of repetitions yk can be set corresponding to the power consumption, the current value, and the like.

  By the way, in the present embodiment, the operator can arbitrarily set the rise time Tk, but depending on the setting, it may be difficult to reduce the inrush current.

  Therefore, a third embodiment of the present invention will be described in which the operator can arbitrarily set the rise time Tk and the inrush current can be made sufficiently small. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by providing the same code | symbol, and the effect of the same embodiment is used about the effect of the invention by having the same structure. .

  FIG. 11 is a block diagram of a heater drive circuit in the third embodiment of the present invention.

  As shown in the figure, the heater drive circuit 40 is provided with drive elements 61 and 62, and the drive elements 61 and 62 can drive the heaters 14 and 17 as the first and second heating bodies. It is like that. A heater selection switching circuit 63 is provided, and the heaters 14 and 17 are turned on alternately by turning on and off the drive elements 61 and 62 alternately. Noise filters 64 and 65 are connected to the heaters 14 and 17, respectively.

  Therefore, the heater lighting signal is generated in the same manner as in the first embodiment, but is generated by alternately masking the zero-cross timing every other time.

  Next, the operation of the image forming apparatus having the above configuration will be described.

  FIG. 12 is a flowchart showing the operation of the image forming apparatus according to the third embodiment of the present invention, and FIG. 13 is a time chart showing the operation of the image forming apparatus according to the third embodiment of the present invention.

  In this case, it waits for the power switch to be turned on, and when the power switch is turned on, the temperature control unit 24a as the temperature control processing means of the sequence control unit 24 (FIG. 1) has a rise time Tk. It is determined whether or not the rise time Tk is set. If the rise time Tk is set, the temperature control process is performed according to the rise time Tk. Then, the drive processing means of the CPU 44 reads the on-duty xk, the added value Δxk, and the number of repetitions yk corresponding to the set rise time Tk, and based on the on-duty xk, the added value Δxk, and the number of repetitions yk. The heater lighting signal is turned on / off to turn on the heaters 14 and 17.

  Next, the interruption information determination processing means of the sequence control unit 24 refers to the storage unit 24b as a memory to determine whether or not the commercial power supply 35 as a power source has been interrupted, and whether or not the storage unit 24b has the interruption information. When the commercial power supply 35 is cut off, the drive processing means turns on / off a heater lighting signal for lighting at least a predetermined heater, in the present embodiment, the heaters 14 and 17. That is, in the present embodiment, the drive processing means turns on the heaters 14 and 17 alternately.

  Thus, in this embodiment, as shown in FIG. 13, when the heaters 14 and 17 are turned on at the same time, the inrush current I3 flows through the heater currents of the heaters 14 and 17, and the inrush current I4 in total On the other hand, when the heaters 14 and 17 are turned on alternately, the inrush current I3 alternately flows in the heater currents of the heaters 14 and 17, and the inrush current I3 remains in total. Therefore, the inrush current I3 can be made sufficiently small.

Next, a flowchart will be described.
Step S21 Wait for the power switch to be turned on. If the power switch is turned on, the process proceeds to step S22.
Step S22 Wait for the rise time Tk to be set, and when the rise time Tk is set, proceed to Step S23.
Step S23: It is determined whether or not the commercial power source 35 is shut off. If the commercial power source 35 is shut off, the process proceeds to step S25. If the commercial power source 35 is not shut off, the process proceeds to step S24.
Step S24: The heaters 14 and 17 are turned on simultaneously.
Step S25 The heaters 14 and 17 are turned on alternately.
Step S26 The temperature control process is started according to the rise time Tk.
Step S27: It is determined whether or not the fixing set temperature has been reached. If the fixing set temperature has been reached, the process proceeds to step S28, and if not, the process returns to step S26.
Step S28: Display the printable state, shift to the standby state, and end the process.

  In the present embodiment, the heaters 14 and 17 are alternately turned on, but a heater lighting signal for driving one of the heaters 14 and 17 is turned on / off for the number of repetitions yk. Subsequently, both heater lighting signals can be turned on.

  In each of the above embodiments, the fixing device including the fixing roller 12 and the pressure roller 15 has been described. However, the present invention can also be applied to a fixing device including a fixing belt.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

1 is a block diagram illustrating a control device of an image forming apparatus according to a first embodiment of the present invention. 10 is a time chart showing the operation of a conventional fixing device. 1 is a cross-sectional view of a fixing device according to a first embodiment of the present invention. It is a block diagram which shows the heater drive circuit in the 1st Embodiment of this invention. 3 is a flowchart showing an operation of the image forming apparatus in the first embodiment of the present invention. It is a 1st time chart which shows the operation | movement of the temperature control process when the normal power mode in the 1st Embodiment of this invention is selected. It is a 2nd time chart which shows the detailed operation | movement of a temperature control process when the normal power mode in the 1st Embodiment of this invention is selected. It is a time chart which shows operation | movement of the temperature control process when the low power consumption mode in the 1st Embodiment of this invention is selected. 6 is a flowchart illustrating an operation of the image forming apparatus according to the second embodiment of the present invention. It is a figure which shows the on-duty table in the 2nd Embodiment of this invention. It is a block diagram of the heater drive circuit in the 3rd Embodiment of this invention. 10 is a flowchart illustrating an operation of an image forming apparatus according to a third embodiment of the present invention. 10 is a time chart illustrating an operation of the image forming apparatus according to the third embodiment of the present invention.

Explanation of symbols

12 Fixing rollers 13 and 16 Thermistors 14 and 17 Heater 15 Pressure roller 20 Image forming apparatus 24 Sequence control unit 24a Temperature control unit 35 Commercial power supply 44 CPU

Claims (7)

(A) a heating body for heating the fixing roller;
(B) a temperature detector for detecting the temperature of the fixing roller;
(C) drive processing means for driving the heating body by turning on / off a drive signal as the power is turned on;
(D) An image forming apparatus comprising duty change processing means for changing the duty of the drive signal. (A) having mode selection processing means for selecting a normal power mode for driving the heating body with normal power consumption and a low power consumption mode for driving the heating body with small power consumption;
(B) The image forming apparatus according to claim 1, wherein the duty change processing unit changes the duty in accordance with the selected mode.   The image forming apparatus according to claim 2, wherein the mode selection processing unit selects a mode depending on whether or not there is cutoff information indicating that the power source is shut off.   The image forming apparatus according to claim 2, wherein the mode selection processing unit selects a mode based on an operation of an operator.   The image forming apparatus according to claim 1, wherein the duty change processing unit changes the duty based on a rise time input by an operator. (A) having a plurality of heating elements;
(B) The drive processing means turns on / off a drive signal for driving a predetermined heating body among the heating bodies as the power is turned on. The image forming apparatus described in the item. In an image forming apparatus including a fixing device that fixes a toner image to a print medium,
(A) A first supply mode for supplying a first energy and a second supply mode for supplying a second energy smaller than the first energy are selected in order to cause the heating body of the fixing device to generate heat. Mode selection processing means to perform,
(B) An image forming apparatus comprising: a heating element driving processing unit that drives the heating element in accordance with a supply mode selected by the mode selection processing unit.

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