JP2008039923A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of times of executing life detection processing and to accurately judge the life of an electric double layer capacitor while suppressing the performance reduction and power loss of an image forming apparatus due to the execution of the life detection processing as much as possible. <P>SOLUTION: A charge/discharge frequency counting part 102 counts the charge/discharge frequency of the electric double layer capacitor 24. A frequency control part 103 increases the execution frequency of the life detection processing by a life detection processing execution part 104 in accordance with the approach of the charge/discharge frequency counted by the charge/discharge frequency counting part 102 to the life charge/discharge frequency indicating the life of the electric double layer capacitor 24. The life detection processing execution part 104 obtains the internal resistance of the electric double layer capacitor 24 by specifying a voltage rise value at the end of charging of the electric double layer capacitor 24 to detect the life of the electric double layer capacitor 24. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having a fixing device for fixing toner on a recording sheet.

  In recent years, the fixing device is provided with two heaters, one heater is heated by electric power from a commercial power supply, and the other heater is heated by electric power stored in a capacitor, thereby quickly fixing the temperature of the fixing roller to a predetermined level. An image forming apparatus capable of increasing to a temperature is known. In such an image forming apparatus, when the capacitor deteriorates, the temperature of the fixing roller cannot be quickly raised.

Therefore, in Patent Documents 1 and 2, when the voltage value of the capacitor that supplies power to one of the two heaters included in the fixing device reaches a specified value, discharging of the capacitor is started. An image forming apparatus is disclosed in which the elapsed discharge time required to reach a voltage value is measured, and the measured elapsed discharge time is compared with a preset specified value to determine the life of the capacitor.
JP 2004-302190 A JP 2004-287007 A

  However, since the methods of Patent Documents 1 and 2 each determine the life of the capacitor every time charging and discharging are performed, there arises a problem that the performance of the image forming apparatus deteriorates.

  An object of the present invention is to reduce the number of times the life detection process for detecting whether or not the capacitor is at the end of its life, and to suppress degradation in performance and power loss of the image forming apparatus due to the execution of the life detection process as much as possible. An object of the present invention is to provide an image forming apparatus capable of accurately detecting the life of a capacitor.

  An image forming apparatus according to the present invention includes a capacitor, a first heating device that heats the fixing roller with electric power discharged from the capacitor, and a second heating device that heats the fixing roller with electric power from a commercial power source. A fixing device, a charge / discharge number counting means for counting the number of charge / discharge of the capacitor, a life detection process executing means for executing a life detection process for detecting whether or not the capacitor has reached the end of its life, Frequency control means for increasing the execution frequency of the life detection processing as the number of times of charging / discharging counted by the discharge number counting means increases is provided.

  According to this configuration, as the number of charge / discharge cycles increases, the execution frequency of the life detection process for detecting the life of the capacitor increases. As a result of increasing the frequency, it is possible to accurately detect the life of the capacitor while minimizing performance degradation and power loss of the image forming apparatus due to execution of life detection processing.

  In addition, the frequency control means specifies a value range among a plurality of predetermined value ranges in which the number of times of charging / discharging counted by the charge / discharge counting unit belongs, and is predetermined for the specified value range. It is preferable that the life detection process execution means execute the life detection process according to the execution frequency.

  According to this configuration, the life detection process is executed by the life detection process execution means in accordance with a predetermined execution frequency with respect to the value range to which the charge / discharge number belongs. As the time goes on, the execution frequency of the life detection process can be increased.

  Further, the frequency control means reduces the execution frequency of the life detection process to 0 until the number of times of charging / discharging counted by the charge / discharge counting means exceeds a predetermined value close to the number of times of life charging / discharging indicating the life of the capacitor. When the predetermined numerical value is exceeded, it is preferable to cause the life detection process execution means to execute the life detection process according to a predetermined execution frequency.

  According to this configuration, the life detection process is not executed until a predetermined value close to the number of charge / discharge cycles indicating the life of the capacitor is exceeded, and after the predetermined value is exceeded, the life detection process is performed according to a predetermined execution frequency. Therefore, the frequency of executing the life detection process can be increased as the number of times of charging / discharging is increased.

  Further, the life detection processing execution means specifies a voltage increase value generated at the end of discharging of the capacitor, calculates an internal resistance of the capacitor from the specified voltage increase value, and the calculated internal resistance value is less than a specified value. When it is larger, it is preferable to determine that the capacitor has a lifetime.

  According to this configuration, since the lifetime of the capacitor is determined using the characteristic that the internal resistance increases as the deterioration progresses, the lifetime of the capacitor can be accurately detected.

  In addition, it is preferable to further include an informing unit for informing that when the life detection processing execution unit determines that the capacitor is at the end of its life.

  According to this configuration, since the life of the capacitor is notified, the user can quickly recognize the life of the capacitor, and can take subsequent measures promptly.

  According to the present invention, as the possibility of the life of the capacitor increases, the execution frequency of the life detection process is increased. As a result, the performance deterioration and power loss of the image forming apparatus due to the execution of the life detection process are suppressed as much as possible. The life of the capacitor can be accurately detected.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view mainly showing a mechanical configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus according to the present embodiment includes a main body unit 200, a sheet post-processing unit 300 disposed on the left side of the main body unit 200, an operation unit 400 for a user to input various operation commands and the like, The document reading unit 500 is disposed above the unit 200, and the document feeding unit 600 is disposed above the document reading unit 500.

  The operation unit 400 includes a display panel 401, a start key 402, a numeric keypad 403, and the like. The display panel 401 is composed of a touch panel and displays various operation images. A start key 402 is used for a user to input an operation command to start copying, and a numeric keypad 403 is used to input the number of copies to be printed.

  The document feeding unit 600 includes a document placement unit 601, a document discharge unit 602, a paper feed roller 603, a document transport unit 604, a contact glass 605, and the like, and the document reading unit 500 includes an image sensor 501 and the like. The paper feed roller 603 feeds the original set on the document placement unit 601, and the document transport unit 604 transports the fed document one by one on the image sensor 501 in order.

  The image sensor 501 sequentially reads the conveyed document, and the read document is discharged to the document discharge unit 602. Further, when reading the document placed on the contact glass 605, the image sensor 501 slides in the A direction to read the document.

  The main body 200 includes a plurality of paper feed cassettes 201, a plurality of paper feed rollers 202, a transfer roller 203, a photosensitive drum 204, an exposure device 205, a developing device 206, a fixing roller 208, a discharge port 209, a discharge tray 210, and a recording. A paper transport unit 211 and the like are provided.

  The photosensitive drum 204 is uniformly charged by a charging device (not shown) while rotating in the direction of the arrow. The exposure device 205 converts the modulation signal generated based on the image data of the document read by the document reading unit 500 into a laser beam and outputs it, and forms an electrostatic latent image on the photosensitive drum 204. The developing device 206 supplies a developer to the photosensitive drum 204 to form a toner image.

  On the other hand, the paper feeding roller 202 pulls out the recording paper from the paper feeding cassette 201 in which the recording paper is stored, and the recording paper transport unit 211 transports the drawn recording paper to the transfer roller 203. The transfer roller 203 transfers the toner image on the photosensitive drum 204 to the conveyed recording paper. The recording paper to which the toner image has been transferred is conveyed to the fixing roller 208 by the recording paper conveyance unit 211, and the fixing roller 208 heats and transfers the transferred toner image to the recording paper. Thereafter, the recording paper is conveyed to the discharge port 209 by the recording paper conveyance unit 211 and is carried into the paper post-processing unit 300. The recording paper is also discharged to the discharge tray 210 as necessary.

  The paper post-processing unit 300 includes a carry-in port 301, a recording paper transport unit 302, a carry-out port 303, a stack tray 304, and the like. The recording paper transport unit 302 sequentially transports the recording paper carried into the carry-in port 301 from the discharge port 209 and finally ejects the recording paper from the carry-out port 303 to the stack tray 304. The stack tray 304 is configured to move up and down in the direction of the arrow in accordance with the number of recording sheets stacked from the carry-out port 303.

  FIG. 2 is a block diagram of the image forming apparatus according to this embodiment. The image forming apparatus according to the present embodiment includes a control unit 10, a heating control unit 20, a fixing device 30, an operation display unit 40, a scanner unit 50, and a printing unit 60.

  The control unit 10 includes, for example, a CPU, a ROM, a RAM, and a dedicated hardware circuit, controls the entire image forming apparatus, a mode setting unit 101, a charge / discharge number counting unit 102, a frequency control unit 103, and a lifetime. A detection processing execution unit 104 is provided. The heating control unit 20 includes a rectifying circuit 21, a charging circuit 22, an AC heater driving circuit 23, an electric double layer capacitor 24, a discharging circuit 26, a current measuring unit 27, and a voltage detection circuit 28.

  The rectifier circuit 21 includes, for example, a diode bridge circuit and a smoothing capacitor. The rectifier circuit 21 is connected between the power supply terminal T1 and the power supply terminal T2 of the commercial power supply 70, and full-wave rectifies the AC voltage supplied from the commercial power supply 70. The rectified AC voltage is smoothed to generate a DC voltage, which is output to the charging circuit 22.

  The charging circuit 22 is composed of, for example, a DC / DC converter, and boosts or steps down the DC voltage output from the rectifier circuit 21 to a DC voltage of a level suitable for charging the electric double layer capacitor 24. To charge. The charging circuit 22 starts charging the electric double layer capacitor 24 when the control unit 10 sets the operation mode of the image forming apparatus to the normal operation mode. The normal operation mode will be described later.

  Further, the charging circuit 22 measures the voltage between the terminals of the electric double layer capacitor 24, and the measured voltage between the terminals reaches a predetermined full voltage value indicating that the remaining capacity of the electric double layer capacitor 24 is full. When it is determined that the electric double layer capacitor 24 is in a fully charged state, the supply of the DC voltage from the rectifier circuit 21 to the electric double layer capacitor 24 is cut off to protect the electric double layer capacitor 24 from overcharging. The AC heater drive circuit 23 is composed of, for example, an AC / AC converter, is connected between the power supply terminals T1 and T2, and converts the AC voltage from the commercial power supply 70 to a level suitable for driving the heater 32 (second heating device). Is output to the heater 32 to cause the heater 32 to generate heat.

  The electric double layer capacitor 24 is charged by the DC voltage output from the charging circuit 22, and outputs the charged voltage to the heater 31 (first heating device) to cause the heater 31 to generate heat. Here, the electric double layer capacitor 24 has a characteristic that it deteriorates as the number of times of charging / discharging increases and the internal resistance increases.

  The discharge circuit 26 is composed of, for example, a constant voltage circuit, generates a constant voltage at a level suitable for driving the heater 31 from the discharge voltage output from the electric double layer capacitor 24, and outputs the constant voltage to the heater 31. In addition, the discharge circuit 26 monitors the value of the discharge current measured by the current measuring unit 27, determines that the discharge has ended when the value of the discharge current becomes 0, and notifies the control unit 10 of the discharge end. Output.

  The current measuring unit 27 is connected between the electric double layer capacitor 24 and the discharge circuit 26, measures the discharge current of the electric double layer capacitor 24 at a constant sampling interval, and has a voltage value at a level corresponding to the magnitude of the discharge current. Is output to the discharge circuit 26 and the control unit 10.

  The voltage detection circuit 28 is composed of a bottom hold circuit, detects the lowest voltage of the electric double layer capacitor 24 at regular time intervals under the control of the control unit 10, and uses the detected lowest voltage of the electric double layer capacitor 24. It outputs to the control part 10 as a voltage measured value.

  A mode setting unit 101 sets an operation mode of the image forming apparatus. As an operation mode of the image forming apparatus, there are a normal operation mode and a power saving mode. In the power saving mode, the power consumption of the image forming apparatus is normally operated by cutting off the power supply to some units constituting the image forming apparatus or turning off the backlight of the operation display unit 40. This mode is lower than the mode consumption. The normal operation mode is a mode at the time of normal operation of the image forming apparatus set when the image forming apparatus reads an original or prints the read original on a recording sheet.

  In addition, when setting the operation mode of the image forming apparatus to the normal operation mode, the mode setting unit 101 outputs a discharge start notification to the discharge circuit 26 and causes the discharge circuit 26 to start discharging the electric double layer capacitor 24. Here, the time when the mode setting unit 101 sets the operation mode of the image forming apparatus to the normal operation mode includes the time when the main power of the image forming apparatus is turned on. In addition, when the operation mode is set to the normal operation mode, the mode setting unit 101 changes the operation mode from the normal operation mode to the power saving mode when the operation display unit 40 does not accept an operation command from the user for a certain period of time. Transition. Furthermore, when the operation mode is set to the power saving mode, the mode setting unit 101 changes the operation mode from the power saving mode to the normal operation mode when the operation display unit 40 receives an operation command from the user.

  The charge / discharge number counting unit 102 includes a charge / discharge number counter 102a that counts the number of charge / discharge of the electric double layer capacitor 24. When the mode setting unit 101 outputs a discharge start notification to the discharge circuit 26, the electric double layer capacitor 24 The charging / discharging counter 102a is counted up by one time.

  The frequency control unit 103 includes a frequency counter 103a for determining the timing of outputting a life detection process execution command to the life detection process execution unit 104. The frequency control unit 103 refers to a frequency determination table to be described later and counts by the charge / discharge frequency counting unit 102. It is specified which value range the plurality of charged / discharged times belong to among a plurality of predetermined value ranges. Then, when the specified value range is the value range specified for the first time this time, the frequency control unit 103 specifies the execution frequency of the life detection process predetermined for the specified value range, and stores the specified execution frequency in the frequency counter 103a. Each time the count value of the frequency counter 103a reaches the set execution frequency, the frequency counter 103a outputs a life detection process execution command, and the life detection process execution unit 104 executes the life detection process.

  The frequency counter 103a counts up every time the charge / discharge counter 102a counts up, and when the count value reaches the execution frequency set by the frequency control unit 103, the life detection process execution unit 104 is instructed to execute a life detection process execution command. Is output. The frequency counter 103a sets the count value to 0 when the life detection process execution command is output.

  FIG. 3 is a diagram illustrating an example of the frequency determination table. As shown in FIG. 3, the frequency determination table includes a charge / discharge frequency column and an execution frequency column. N1 to n3 and N shown in FIG. 3 have a relationship of n1 <n2 <n3 <N. N represents the number of charge / discharge cycles that indicates that the electric double layer capacitor 24 has reached the end of its life.

  The frequency counter 103a outputs a life detection process execution command to the life detection process execution unit 104 every time the count value reaches 10 when the frequency control unit 103 specifies that the charge / discharge count belongs to a value range less than n1. . In addition, when the frequency control unit 103 specifies that the number of times of charge / discharge belongs to a value range of n1 or more and less than n2, the frequency counter 103a performs a life detection process on the life detection process execution unit 104 every time the count value reaches 8. Output a command. Further, when the frequency control unit 103 specifies that the number of times of charge / discharge belongs to a value range of n2 or more and less than n3, the frequency counter 103a performs the life detection process execution unit 104 every time the count value reaches 4. Output a command. In addition, when the frequency control unit 103 specifies that the frequency of charging / discharging belongs to a value range of n3 or more and less than N, the frequency counter 103a causes the life detection processing execution unit 104 to execute a life detection process every time the count is increased. That is, the frequency control unit 103 controls the life detection processing execution unit 104 so that the frequency of execution of the life detection processing increases as the number of charge / discharge of the electric double layer capacitor 24 approaches N, which is the number of life charge / discharge. To do.

  When the life detection process execution unit 104 receives a life detection process execution command from the frequency control unit 103, the life detection process execution unit 104 executes a life detection process for detecting whether or not the electric double layer capacitor 24 has a life. Specifically, the life detection processing execution unit 104 specifies a voltage increase value that is a jump of the voltage after the end of the discharge of the electric double layer capacitor 24, and uses the specified voltage increase value as the end of discharge end of the electric double layer capacitor 24. When the calculated internal resistance is larger than a predetermined lifetime internal resistance value indicating the lifetime of the electric double layer capacitor 24, the electric double layer capacitor 24 It is determined that it is a lifetime. Furthermore, when the number of times of charging / discharging of the electric double layer capacitor 24 counted by the charge / discharge number counting unit 102 reaches N, the life detection processing execution unit 104 determines that the electric double layer capacitor 24 has a life.

  The fixing device 30 includes heaters 31 and 32. The heater 31 is disposed inside the fixing roller 208 and generates heat by the voltage output from the electric double layer capacitor 24 to heat the fixing roller 208.

  The heater 32 is disposed inside the fixing roller 208 and generates heat by the AC voltage output from the AC heater driving circuit 23 to heat the fixing roller 208. The operation display unit 40 includes the operation unit 400 shown in FIG. 1, and displays information indicating that the life has been reached when the life detection processing execution unit 104 determines that the electric double layer capacitor 24 has reached the life. To do.

  The scanner unit 50 includes a document reading unit 500 shown in FIG. 1, and acquires image data of a document. The printing unit 60 includes the transfer roller 203, the photosensitive drum 204, the exposure device 205, and the developing device 206 shown in FIG. 1, and prints document image data acquired by the scanner unit 50 on recording paper.

  Next, the operation of the image forming apparatus according to the present embodiment centering on the heating control unit 20 will be described with reference to FIG. FIG. 4 shows a waveform diagram of the voltage of the electric double layer capacitor 24. In the initial state, the electric double layer capacitor 24 is in a fully charged state, and the operation mode of the image forming apparatus is set to the power saving mode. First, when the operation display unit 40 is operated by the user, the mode setting unit 101 changes the operation mode of the image forming apparatus from the power saving mode to the normal operation mode, and causes the discharge circuit 26 to connect the electric double layer capacitor 24. Discharging is started (time KT1), and heating of the heater 31 is started. At this time, the charge / discharge number counting unit 102 increments the charge / discharge number counter 102a by one.

  At this time, the frequency control unit 103 uses the frequency specifying table shown in FIG. 3 to specify the value range to which the number of times of charging / discharging counted by the charging / discharging number counting unit 102 belongs. It is determined whether or not they are different, that is, whether or not the specified value range is the value range specified for the first time this time. When the specified range is the first specified range this time, the frequency control unit 103 sets a predetermined execution frequency for the specified range in the frequency counter 103a and increments the frequency counter 103a by one. . On the other hand, when the specified range is the same as the previously specified range, the frequency control unit 103 counts up the frequency counter 103a without setting the execution frequency in the frequency counter 103a.

  Then, when the count value reaches the set execution frequency, the frequency counter 103a outputs a life detection process execution command to the life detection process execution unit 104. On the other hand, if the count value has not reached the set execution frequency, the frequency counter 103a does not output a life detection process execution command to the life detection process execution unit 104.

  For example, when the frequency counter 103a counts the number of times of charge / discharge counted by the charge / discharge counter 102a is n2 or more and less than n3, the frequency of execution is four as shown in the frequency specification table. Each time the value reaches 4, a life detection process execution command is output to the life detection process execution unit 104. Thereby, the lifetime detection process execution part 104 performs a lifetime detection process only once out of 4 times charging / discharging.

  The frequency counter 103a increments the count value by 1 when the charge / discharge count counted by the charge / discharge count counter 102a is n3 or more and less than N because the execution frequency is 1 as shown in the frequency specification table. Each time, a life detection process execution command is output to the life detection process execution unit 104. Thereby, the lifetime detection process execution part 104 performs a lifetime detection process whenever charging / discharging is performed once.

  It is assumed that the count value of the frequency counter 103a has reached the set execution frequency at time KT1 in FIG. Then, the life detection process execution part 104 performs a life detection process, and determines whether the electric double layer capacitor 24 has reached the life.

  Specifically, the life detection process execution unit 104 first monitors the voltage measurement value output from the voltage detection circuit 28, and specifies the lowest value of the voltage measurement value as the discharge end voltage (time KT2). Next, the life detection processing execution unit 104 monitors the voltage measurement value output from the voltage detection circuit 28 after specifying the discharge end voltage, and the voltage measurement value when the change in the voltage measurement value becomes substantially constant. Is specified as the return voltage (time KT3). Note that at time KT2, the control unit 10 does not cause the charging circuit 22 to start charging in order to specify the return voltage even when receiving a discharge end notification output from the discharge circuit 26. Here, after the discharge is completed, the voltage of the electric double layer capacitor 24 increases from the charge end voltage to the return voltage because the voltage drop due to the internal resistance of the electric double layer capacitor 24 disappears when the discharge current becomes zero. Therefore, since the voltage increase value after the end of charging increases according to the magnitude of the internal resistance, the internal resistance of the electric double layer capacitor 24 can be accurately obtained by specifying the voltage increase value.

  Next, the life detection process execution unit 104 subtracts the discharge end voltage from the return voltage to calculate a voltage increase value. Next, the life detection process execution unit 104 acquires the value of the discharge current immediately before the end of the discharge from the current measurement unit 27, and divides the voltage increase value by the acquired discharge current, so that the electric double layer capacitor 24 Calculate the internal resistance. Here, the life detection processing execution unit 104 monitors the value of the discharge current detected by the current measurement unit 27 at a constant sampling interval, and acquires the value of the discharge current immediately before becoming 0 as the discharge current at the end of discharge. .

  Next, when the calculated internal resistance is greater than a predetermined lifetime internal resistance value indicating the lifetime of the electric double layer capacitor 24, the lifetime detection processing execution unit 104 determines that the electric double layer capacitor 24 has reached the lifetime. . On the other hand, when the calculated internal resistance is equal to or less than the lifetime internal resistance value, the lifetime detection processing execution unit 104 determines that the electric double layer capacitor 24 has not reached the lifetime.

  In addition, when it is determined that the electric double layer capacitor 24 has reached the life, the life detection processing execution unit 104 displays information indicating that the electric double layer capacitor 24 has reached the life on the operation display unit 40. In this case, the operation display unit 40 displays, for example, a phrase such as “The electric double layer capacitor has a lifetime”. By performing the above processing, the life detection processing execution unit 104 determines the life of the electric double layer capacitor 24.

  When the life detection process execution unit 104 determines that the voltage of the electric double layer capacitor 24 has reached the return voltage at time KT3 illustrated in FIG. 4, the control unit 10 causes the charging circuit 22 to start charging the electric double layer capacitor 24. .

  Next, when the charging circuit 22 determines that the voltage of the electric double layer capacitor 24 has reached the full voltage, the charging circuit 22 ends the charging of the electric double layer capacitor 24 (time KT4).

  Next, mode setting unit 101 causes discharge circuit 26 to start discharging electric double layer capacitor 24 in the same manner as time KT1 (time KT5). Here, it is assumed that the count value counted up by the frequency counter 103 a has not reached the execution frequency specified by the frequency control unit 103. Therefore, the life detection process execution unit 104 does not execute the life detection process.

  Next, when it is determined by the discharge circuit 26 that the electric double layer capacitor 24 has been discharged, and the control unit 10 receives a discharge end notification (time KT6), the control unit 10 starts charging the electric double layer capacitor 24 to the charging circuit 22. Let Here, when the control unit 10 accepts the discharge end notification, the charging circuit 22 immediately starts charging, so that the electric double layer capacitor 24 is fully charged without the return voltage appearing at time KT3. (Time KT7).

  As described above, according to the present image forming apparatus, as the charge / discharge frequency of the electric double layer capacitor 24 approaches the predetermined lifetime charge / discharge frequency, the frequency of execution of the life detection process by the life detection process execution unit 104 is increased. Therefore, as the possibility of the life of the electric double layer capacitor 24 increases, the execution frequency of the life detection process is increased. As a result, the performance degradation and power loss of the image forming apparatus due to the execution of the life detection process are minimized. The lifetime of the electric double layer capacitor 24 can be accurately detected while suppressing.

  In the above embodiment, the frequency control unit 103 specifies the execution frequency of the life detection process using the frequency specification table shown in FIG. 3, but is not limited to this, and as shown in FIG. When the number of times is less than n1, the life detection process is not executed by the life detection process execution unit 104. When the number of charge / discharge is n1 or more, the life detection process is performed every time the charge / discharge number is counted once. You may make the execution part 104 perform a lifetime detection process. In FIG. 5, the execution frequency is set to once, but this is only an example, and the execution frequency may be set to a plurality of times such as 2, 3, and 4 times.

  Further, in the above embodiment, the lifetime is detected by calculating the internal resistance of the electric double layer capacitor 24 from the voltage rise value at the end of charging, but the present invention is not limited to this, and the time from the start of charging to the end of charging is set to If the measured time is equal to or greater than a specified value, it may be determined that the life has been reached.

  Furthermore, in the above-described embodiment, the number of times of charging / discharging is counted as one at the start of discharging. However, the present invention is not limited to this, and the number of times of discharging is counted as one at the start of discharging or at the end of discharging. At the end of charging, the number of times of charging is counted as one, the number of times of discharging and the number of times of charging are added to determine the number of times of charging and discharging, and the frequency of performing the life detection process may be specified using this number of times of charging and discharging. . Further, the execution frequency of the life detection process may be specified by using only the number of charge / discharge or only the number of discharge as the number of charge / discharge. Furthermore, although four value ranges are shown in FIG. 3, the present invention is not limited to this, and a number value range other than 4 such as 2, 3 or 5, 6 may be provided.

1 is a schematic side view mainly showing a mechanical configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram of an image forming apparatus according to the present embodiment. It is the figure which showed an example of the frequency determination table. The waveform diagram of the voltage of the electric double layer capacitor is shown. It is the figure which showed the other example of the frequency determination table.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Control part 20 Heating control part 21 Rectification circuit 22 Charging circuit 23 AC heater drive circuit 24 Electric double layer capacitor 26 Discharge circuit 27 Current measurement part 28 Voltage detection circuit 30 Fixing device 31, 32 Heater 40 Operation display part 50 Scanner part 60 Printing Unit 70 commercial power source 101 mode setting unit 102a charge / discharge number counter 102 charge / discharge number count unit 103a frequency counter 103 frequency control unit 104 life detection process execution unit

Claims (5)

A capacitor;
A fixing device comprising: a first heating device that heats the fixing roller with electric power discharged from the capacitor; and a second heating device that heats the fixing roller with electric power from a commercial power source;
Charge / discharge number counting means for counting the number of charge / discharge of the capacitor;
A life detection process execution means for executing a life detection process for detecting whether or not the capacitor has reached the end of its life;
An image forming apparatus comprising: a frequency control unit configured to increase an execution frequency of the life detection process as the number of times of charging / discharging counted by the number of times of charging / discharging increases.   The frequency control means specifies a value range among a plurality of predetermined value ranges in which the number of times of charging / discharging counted by the charge / discharge counting means belongs, and a predetermined execution frequency for the specified value range The image forming apparatus according to claim 1, wherein the life detection processing execution unit causes the life detection processing to be executed.   The frequency control means sets the execution frequency of the life detection process to 0 until the charge / discharge count counted by the charge / discharge count means exceeds a predetermined numerical value close to the life charge / discharge count indicating the life of the capacitor, 2. The image forming apparatus according to claim 1, wherein when the predetermined numerical value is exceeded, the life detection processing execution unit is caused to execute the life detection processing according to a predetermined execution frequency.   The life detection processing execution means specifies a voltage increase value generated at the end of discharging of the capacitor, calculates an internal resistance of the capacitor from the specified voltage increase value, and the calculated internal resistance value is larger than a specified value The image forming apparatus according to claim 1, wherein the capacitor is determined to have a lifetime.   5. The image forming apparatus according to claim 1, further comprising a notifying unit that notifies when the capacitor is determined to have a lifetime by the lifetime detection processing execution unit.

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