JP2020144288A - Image forming device - Google Patents

Abstract

To provide an image forming device capable of distinguishing a failure related to a generator circuit for generating zero-cross signals and a stoppage of the supply of AC voltage from an AC power supply.SOLUTION: The image forming device measures the elapsed time using the zero-cross timing indicated by a zero-cross signal as the reference. When the elapsed time exceeds the time of a first threshold value, the image forming device determines that the output of the zero-cross signal by generating means has stopped. When the elapsed time exceeds the time of a second threshold value, the image forming device determines that a failure related to the generating means has occurred. The second threshold value time is longer than the operation time that the control means can continuously operate using a DC voltage supplied from a capacitive element after an AC voltage supply has stopped. The first threshold value time is shorter than the operation time.SELECTED DRAWING: Figure 7

Description

The present invention relates to an electronic device and an image forming apparatus having a circuit for generating a zero cross signal of an AC voltage.

The image forming apparatus controls the heater of the fixing apparatus by using the AC voltage supplied from the AC power source. The image forming apparatus controls the electric power supplied to the heater with reference to the Xerox timing of the AC voltage in order to maintain the temperature of the heater at the target temperature. Therefore, if the generation circuit that generates the zero-cross signal fails, the image forming apparatus cannot form an image. According to Patent Document 1, a method for distinguishing between a state in which the AC power cord is disconnected and a state in which an abnormality has occurred in the AC power supply has been proposed.

Japanese Unexamined Patent Publication No. 2005-128688

However, the invention described in Patent Document 1 cannot distinguish between a failure related to a generation circuit that generates a zero-cross signal and an AC voltage supply stoppage (power loss) from an AC power supply. Therefore, it is an object of the present invention to distinguish between a failure related to a generation means for generating a zero-cross signal and an AC voltage supply stoppage from an AC power source.

The present invention is, for example,
A conversion means that converts AC voltage supplied from an AC power supply into DC voltage,
Capacitive elements charged by the DC voltage and
A control means that operates using the DC voltage or the DC voltage supplied from the capacitive element as a power supply voltage, and
It has a generation means for generating a zero-cross signal indicating the zero-cross timing of the AC voltage.
The control means
A time measuring means for measuring the elapsed time based on the zero cross timing indicated by the zero cross signal, and
When the elapsed time exceeds the first threshold time, the stop determination means for determining that the output of the zero cross signal by the generation means has stopped, and the stop determination means.
When the stop determining means determines that the output of the zero cross signal has stopped, the saving means for executing the saving processing of information from the volatile storage unit to the non-volatile storage unit, and the saving means.
A failure determining means for determining that a failure related to the generating means has occurred when the elapsed time exceeds the second threshold time, and
Have,
The second threshold time is longer than the operating time during which the control means can be continuously operated by the DC voltage supplied from the capacitive element after the supply of the AC voltage is stopped.
Provided is an image forming apparatus characterized in that the first threshold time is shorter than the operating time.

According to the present invention, there is provided an image forming apparatus capable of distinguishing a failure related to a generation means for generating a zero-cross signal from an AC voltage supply stoppage from an AC power source.

The figure which shows the image forming apparatus Diagram showing the control unit The figure which shows the function of a CPU Diagram illustrating a zero-cross signal The figure explaining the first threshold time for detecting a zero cross error The figure explaining the second threshold time for detecting the failure of the generation circuit. Flowchart showing how to detect failure of the generator circuit Flowchart showing how to detect failure of the generator circuit

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiment, not all of the plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are given the same reference numbers, and duplicate description is omitted.

[Example 1]
● Image forming apparatus FIG. 1 shows an electrophotographic image forming apparatus 1. The paper cassette 2 and the paper tray 3 are storage means for storing the recording material P. The paper feed rollers 4a and 4b are supply means for sending the recording material P to the transport path and supplying it to the image forming unit 17. The transport path is provided with a transport roller pair 5 and a resist roller pair 6 for transporting the recording material P. The image forming unit 17 is provided with a photosensitive drum 11 that carries an electrostatic latent image or a toner image. The charging roller 12 uniformly charges the surface of the photosensitive drum 11. The exposure unit 13 modulates the laser beam with an image signal corresponding to the input image and deflects the laser beam. As a result, the laser beam scans the surface of the photosensitive drum 11 and an electrostatic latent image is formed. The developing roller 15 develops an electrostatic latent image using toner to form a toner image. The transfer roller 16 transfers the toner image conveyed by the photosensitive drum 11 to the recording material P. While transporting the recording material P, the fixing device 20 applies heat and pressure to the toner image transferred to the recording material P to fix the toner image on the recording material P. The pressure roller 22 is urged to come into contact with the fixing film 24. The heater 23 is in contact with the inner peripheral surface of the cylindrical fixing film 24, and heats the fixing temperature of the fixing film 24 to a target temperature. The paper ejection roller 29 ejects the recording material P on which the toner image is fixed by the fixing device 20.

The control unit 10 is a controller that controls each unit of the image forming apparatus 1. The control unit 10 has a CPU 34 and a storage device 33. The CPU 34 realizes various functions by executing a control program stored in the storage device 33. The CPU 34 determines that a failure related to a generation circuit that generates a zero-cross signal and a stoppage of supply of AC voltage from a commercial AC power supply (power loss), and displays on the display device of the operation unit 30 that the failure has occurred. You may. Alternatively, the CPU 34 may transmit the occurrence of the failure to the server of the company that undertakes the maintenance of the image forming apparatus 1.

● Control unit FIG. 2 shows the details of the control unit 10. The conversion circuit 37 converts the AC voltage supplied via the power plug 41 connected to the AC power supply into a DC voltage and supplies the AC voltage to the CPU 34 or the like. The conversion circuit 37 includes an AC / DC converter, a DC / DC converter, and the like. AC is an abbreviation for alternating current. DC is an abbreviation for direct current. The CPU 34 is a processor that operates when a DC voltage is supplied as an operating voltage. The storage device 33 has a non-volatile memory (eg, hard disk drive, solid state drive, flash memory). The RAM 35 is a volatile memory. The operation unit 30 has a display device 31. NIF36 is a network interface (communication circuit) for communicating with a server. The capacitor 38 is a capacitive element that stores energy by applying a DC voltage supplied from the conversion circuit 37. The capacitor 38 may be a lithium ion battery or the like. When the supply of the AC voltage is stopped, the conversion circuit 37 cannot generate the DC voltage. In this case, the electric charge charged in the capacitor 38 is discharged, so that a DC voltage is supplied as an operating voltage to the CPU 34 and the like. The generation circuit 39 detects the zero cross of the AC voltage and generates a zero cross signal indicating the timing at which the zero cross is detected. The triac 40 supplies an AC voltage to the heater 23 based on the control signal output from the CPU 34. The CPU 34 controls the electric power supplied to the heater 23 with reference to the zero cross timing indicated by the zero cross signal. As a result, the temperature of the heater 23 is maintained at the target temperature. The thermistor for measuring the temperature of the heater 23 is not shown.

● CPU functions As shown in FIG. 3, the CPU 34 realizes various functions according to a control program. Some or all of these functions may be realized by hardware circuits such as ASICs and FPGAs. ASIC is an abbreviation for a special purpose integrated circuit. FPGA is an abbreviation for field programmable gate array.

The timer 301 is a timekeeping circuit that starts timekeeping from 0 when a reset signal generated by the CPU 34 is input. The stop determination unit 302 determines whether or not the elapsed time measured by the timer 301 has exceeded the first threshold time. That is, the stop determination unit 302 detects the occurrence of a zero cross error. When the elapsed time measured by the timer 301 exceeds the first threshold time th1, the stop determination unit 302 outputs a save command to the save unit 304. This is because the cause of the zero cross error may be power loss. When the save command is input, the save unit 304 saves the information stored in the RAM 35 to the storage device 33. The failure determination unit 303 determines whether or not the elapsed time measured by the timer 301 has exceeded the second threshold time. The second threshold time is longer than the first threshold time. When the elapsed time measured by the timer 301 exceeds the second threshold time, the failure determination unit 303 outputs a notification command to the failure notification unit 305. The failure notification unit 305 displays information indicating that a failure related to the generation circuit 39 has occurred on the display device 31 or transmits the information to the server via the NIF 36. The logging unit 306 is an option adopted in the second embodiment.

● First threshold time As shown in FIG. 4, when the AC voltage changes from a value other than zero to zero, the generation circuit 39 outputs a high-level zero cross signal for a certain period of time. If the AC voltage is non-zero, the level of the zero cross signal is low. The stop determination unit 302 resets the timer 301 when a high-level zero cross signal is input before the elapsed time timed by the timer 301 exceeds the first threshold time. As a result, the timer 301 resets the elapsed time to 0 and restarts the time counting of the elapsed time. When simply described as a zero-cross signal, this means a high-level zero-cross signal.

As shown in FIG. 5, the stop determination unit 302 determines that a zero cross error has occurred when the elapsed time measured by the timer 301 exceeds the first threshold time th1. The causes of the zero cross error are that the supply of the AC voltage is stopped and that a failure related to the generation circuit 39 occurs. When the power plug 41 is disconnected from the outlet (receptacle outlet), or when an AC power failure, momentary interruption, or failure occurs, the AC voltage supply is stopped. Failures related to the generation circuit 39 include failures of the generation circuit 39, failures of circuits and wiring existing from the power plug 41 to the generation circuit 39, and failures of the circuits and wiring existing from the generation circuit 39 to the CPU 34. is there. As shown in FIG. 5, the first threshold time th1 is set to a time longer than one cycle of the AC voltage. For example, the first threshold time th1 may be set to 56 ms, which corresponds to 2.5 cycles of alternating current at 50 Hz. ms is an abbreviation for milliseconds. It should be noted that the CPU 34 cannot distinguish that the supply of the AC voltage has stopped and that the failure related to the generation circuit 39 has occurred only when the elapsed time measured by the timer 301 exceeds the first threshold time.

● Second Threshold Time As shown in FIG. 6, the failure determination unit 303 determines whether or not the elapsed time measured by the timer 301 exceeds the second threshold time th2. The second threshold time th2 is a time that is equal to or longer than the discharge time required from the time when the supply of the AC voltage is stopped until the voltage across the capacitor 38 falls below the operating voltage of the CPU 34. For example, the second threshold time th2 may be determined by adding the margin time to the discharge time. The image forming apparatus 1 has a capacitor 38. Therefore, the CPU 34 can continue to operate until a predetermined discharge time elapses after the AC power supply is lost. The discharge time depends on the configuration of the image forming apparatus 1, the operating state (sleep, standby, printing), and the capacity of the capacitor 38. In this example, the discharge time is assumed to be 1500 ms. The margin is assumed to be 500 ms. Therefore, the second threshold time th2 is assumed to be 2000 ms. These numbers are just an example.

When the supply of the AC voltage is stopped, the operation of the CPU 34 is stopped before the elapsed time exceeds the second threshold time th2. On the other hand, when a failure related to the generation circuit 39 occurs, the CPU 34 can continue the operation even after the elapsed time exceeds the second threshold time th2. That is, if the CPU 34 can operate even after the elapsed time exceeds the second threshold time th2, the CPU 34 can conclude that the cause of the stop of the zero cross signal is a failure related to the generation circuit 39.

● Flowchart FIG. 7 shows an error determination executed by the CPU 34. When the image forming apparatus 1 is activated by supplying an AC voltage from a commercial AC power supply, the CPU 34 executes the following processing.

In S701, the CPU 34 (stop determination unit 302) resets the timer 301. As a result, the timer 301 starts timing the elapsed time. The timing for resetting the timer 301 is the timing at which the zero cross signal is input. That is, the zero cross signal may be used as a reset signal for resetting the timer 301.

In S702, the CPU 34 (stop determination unit 302) determines whether or not a zero cross signal has been detected. If the zero cross signal is not at a high level, the CPU 34 advances processing to S703. If the zero-cross signal is at a high level, the CPU 34 advances processing to S701 and resets the timer 301.

In S703, the CPU 34 (stop determination unit 302) determines whether or not the elapsed time measured by the timer 301 exceeds the first threshold time th1. If the elapsed time does not exceed the first threshold time th1, the CPU 34 advances the process to S702. On the other hand, if the elapsed time exceeds the first threshold time th1, the CPU 34 determines that a zero cross error has occurred, and proceeds to the process in S704. As described above, S701 to S703 form a process for detecting the occurrence of a zero cross error.

In S704, the CPU 34 (save unit 304) executes the save process. The save unit 304 stops the image formation process of the image forming device 1, saves information from the RAM 35 to the storage device 33, and reports the occurrence of a zero cross error to the server. The time required for the evacuation process is the time required to complete the operation of the CPU 3 before it stops.

In S705, the CPU 34 (fault determination unit 303) determines whether or not the elapsed time measured by the timer 301 exceeds the second threshold time th2. If the elapsed time does not exceed the second threshold time th2, the CPU 34 advances the process to S707. In S707, the CPU 34 (stop determination unit 302) determines whether or not a zero cross signal has been detected. If the zero cross signal is not at a high level, the CPU 34 advances processing to S705. If the zero-cross signal is at a high level, the CPU 34 advances processing to S701 and resets the timer 301. In this case, the CPU 34 may restart the image forming apparatus 1. On the other hand, if the elapsed time exceeds the second threshold time th2 in S705, the CPU 34 determines that a failure related to the generation circuit 39 has occurred, and proceeds to the process in S706.

In S706, the CPU 34 (fault notification unit 305) notifies the circuit failure. For example, the failure notification unit 305 displays on the display device 31 information indicating that a failure related to the generation circuit 39 has occurred. The failure notification unit 305 transmits information indicating that a failure related to the generation circuit 39 has occurred to the server via the NIF 36.

When the supply of the AC voltage from the AC power supply is stopped, the DC voltage supplied by the capacitor 38 is lower than the operating lower limit voltage of the CPU 34 during the execution of the determination loop formed by S705 and S707. That is, the CPU 34 stops without executing S706.

[Example 2]
As shown in FIG. 8, the second embodiment is obtained by adding a logging process to the first embodiment. S801 and S802 are added between S703 and S704. Further, S803 and S804 are added after S706.

In S801, the CPU 34 (logging unit 306) writes log data indicating that a zero cross error has occurred in the log held in the storage device 33. In S802, the CPU 34 (logging unit 306) writes log data indicating that the AC stop has occurred in the log held in the storage device 33. At this point, it is not certain whether or not the AC voltage supply stop has actually occurred, so this writing is a provisional writing. When it is determined that the AC voltage supply stop has occurred, S803 and S804 are executed in addition to S706.

In S803, the CPU 34 (logging unit 306) deletes the log data indicating that the AC stop has occurred from the log. This is because it has been determined that the cause of the zero cross error is not the stoppage of the AC voltage supply but the failure related to the generation circuit 39. In S804, (logging unit 306) writes log data indicating that a failure related to the generation circuit 39 has occurred in the log.

[Technical Thought and Effect Derived from Examples]
The conversion circuit 37 functions as a conversion means for converting an AC voltage supplied from an AC power source into a DC voltage. The capacitor 38 is an example of a capacitive element that is charged by a DC voltage. The CPU 34 functions as a control means that operates using a DC voltage or a DC voltage supplied from a capacitive element as a power supply voltage. The generation circuit 39 functions as a generation means for generating a zero-cross signal indicating the zero-cross timing of the AC voltage. The timer 301 functions as a time measuring means for measuring the elapsed time based on the zero cross timing indicated by the zero cross signal. The stop determination unit 302 functions as a stop determination means for determining that the output of the zero cross signal by the generation means has stopped when the elapsed time exceeds the first threshold time. When the stop determination means determines that the output of the zero cross signal has stopped, the save unit 304 stores the information as a save means for executing the save process of information from the volatile storage unit to the non-volatile storage unit. The RAM 35 is an example of a volatile storage unit. The storage device 33 is an example of a non-volatile storage unit. The failure determination unit 303 functions as a failure determination means for determining that a failure related to the generation means has occurred when the elapsed time exceeds the second threshold time. Further, the failure determination unit 303 may determine that the generation means has failed when the control means is operating even if the elapsed time exceeds the second threshold time. The second threshold time is longer than the operating time during which the control means can continuously operate due to the DC voltage supplied from the capacitive element after the supply of the AC voltage is stopped. Also, the first threshold time is shorter than this operating time. This provides an image forming apparatus capable of distinguishing a failure related to a generation circuit that generates a zero-cross signal from an AC voltage supply stoppage from an AC power supply.

When the AC power supply supplies the AC voltage, the CPU 34 operates using the DC voltage generated by the conversion means as the power supply voltage. Further, the CPU 34 operates using the DC voltage supplied from the capacitive element as the power supply voltage when the supply of the AC voltage from the AC power supply is interrupted. As a result, even if the supply of the AC voltage is interrupted, the CPU 34 can operate until the DC voltage supplied by the capacitor 38 falls below the operating lower limit voltage of the CPU 34. After that, the operation of the CPU 34 is stopped before the elapsed time exceeds th2, and the process of S803 is not executed, so that the log data written in S802 is retained.

As described in the second embodiment, the storage device 33 and the logging unit 306 serve as holding means for holding log data indicating that the AC power supply has stopped when the stop determination means determines that the output of the zero cross signal has stopped. Function. If the CPU 34 is operating even if the elapsed time exceeds the second threshold time, the CPU 34 and the logging unit 306 may delete the log data indicating that the AC power supply held by the holding means has stopped. This will ensure that the cause of the zero cross error is properly preserved.

When the CPU 34 is operating even if the elapsed time exceeds the second threshold time, the CPU 34 may cause the holding means to hold log data indicating that a failure related to the generation means has occurred. This makes it possible to log the occurrence of a failure related to the generation circuit 39.

The failure notification unit 305, the display device 31, and the NIF 36 serve as output means for outputting information indicating that a failure related to the generation means has occurred when the CPU 34 is operating even if the elapsed time exceeds the second threshold time. Function. The output means may be a display means (eg, display device 31) that displays information indicating that a failure related to the generation means has occurred. This will allow the user to understand that the image forming apparatus 1 needs to be repaired. The output means may be a transmission means (eg, NIF36) that transmits information indicating that a failure related to the generation means has occurred to the server. As a result, the maintenance person will be able to immediately go to repair the image forming apparatus 1. In addition, the time (downtime) during which the image forming apparatus 1 cannot perform image forming will be reduced.

The fuser 20 operates by being supplied with an AC voltage, and functions as a fixing means for fixing the toner image on the sheet. The CPU 34 may control the AC voltage supplied to the fixing means based on the zero cross signal.

When the stop determination means determines that the output of the zero cross signal has stopped, the CPU 34 may reset the timing means to restart the timing. In FIG. 6, this reset is executed when the elapsed time exceeds th1. In this case, the elapsed time compared with th2 will be clocked from the time when the elapsed time exceeds th1. Therefore, th2 may be set to 2000 ms-56 ms = 1944 ms. Further, the timer 301 may have a first timer that measures the elapsed time compared with th1 and a second timer that measures the elapsed time compared with th2. In this case, the first timer may be a countdown type timer in which th1 is set and the countdown is executed. The second timer may be a countdown type timer in which th2 is set and the countdown is executed.

When the CPU 34 is operating even if the elapsed time exceeds the second threshold time, the CPU 34 deletes the log data indicating that the supply of the AC voltage held by the holding means has stopped, and is related to the generating means. The holding means may hold log data indicating that a failure has occurred. The CPU 34 may determine that a failure related to the generation means has occurred when the zero cross signal is lost even though the AC power supply is not lost. The CPU 34 may be configured to stop when the AC power supply is lost and the power supply from the capacitive element is cut off. The capacitive element may be a battery.

The invention is not limited to the above embodiments, and various modifications and modifications can be made without departing from the spirit and scope of the invention. Therefore, claims are attached to make the scope of the invention public.

1 ... Image forming apparatus, 37 ... Conversion circuit 37, 38 ... Capacitor, 34 ... CPU, 39 ... Generation circuit

Claims (13)

A conversion means that converts AC voltage supplied from an AC power supply into DC voltage,
Capacitive elements charged by the DC voltage and
A control means that operates using the DC voltage or the DC voltage supplied from the capacitive element as a power supply voltage, and
It has a generation means for generating a zero-cross signal indicating the zero-cross timing of the AC voltage.
The control means
A time measuring means for measuring the elapsed time based on the zero cross timing indicated by the zero cross signal, and
When the elapsed time exceeds the first threshold time, the stop determination means for determining that the output of the zero cross signal by the generation means has stopped, and the stop determination means.
When the stop determining means determines that the output of the zero cross signal has stopped, the saving means for executing the saving processing of information from the volatile storage unit to the non-volatile storage unit, and the saving means.
A failure determining means for determining that a failure related to the generating means has occurred when the elapsed time exceeds the second threshold time, and
Have,
The second threshold time is longer than the operating time during which the control means can be continuously operated by the DC voltage supplied from the capacitive element after the supply of the AC voltage is stopped.
An image forming apparatus, characterized in that the first threshold time is shorter than the operating time. When the AC power supply supplies the AC voltage, the control means operates using the DC voltage generated by the conversion means as the power supply voltage, and when the supply of the AC voltage from the AC power supply is interrupted. The image forming apparatus according to claim 1, wherein the image forming apparatus operates using the DC voltage supplied from the capacitive element as a power supply voltage. The image according to claim 1 or 2, further comprising a holding means for holding log data indicating that the AC power supply has stopped when the stop determining means determines that the output of the zero cross signal has stopped. Forming device. When the control means is operating even if the elapsed time exceeds the second threshold time, the control means deletes the log data indicating that the AC power supply held by the holding means has stopped. The image forming apparatus according to claim 3. When the control means is operating even if the elapsed time exceeds the second threshold time, the control means causes the holding means to hold log data indicating that a failure related to the generation means has occurred. The image forming apparatus according to claim 3 or 4. When the control means is operating even if the elapsed time exceeds the second threshold time, it is characterized by further having an output means for outputting information indicating that a failure related to the generation means has occurred. The image forming apparatus according to any one of claims 1 to 5. The image forming apparatus according to claim 6, wherein the output means is a display means for displaying information indicating that a failure related to the generation means has occurred. The image forming apparatus according to claim 6, wherein the output means is a transmission means for transmitting information indicating that a failure related to the generation means has occurred to a server. Further having a fixing means for fixing the toner image on the sheet by being supplied with the AC voltage and operating.
The image forming apparatus according to any one of claims 1 to 8, wherein the control means controls the AC voltage supplied to the fixing means based on the zero cross signal. The invention according to any one of claims 1 to 9, wherein when the stop determining means determines that the output of the zero cross signal has stopped, the controlling means resets the timing means and restarts the timing. Image forming device. A conversion means that converts AC voltage supplied from an AC power supply into DC voltage,
Capacitive elements charged by the DC voltage and
When the AC power supply supplies the AC voltage, the DC voltage generated by the conversion means is used as the power supply voltage, and when the supply of the AC voltage from the AC power supply is interrupted, the capacitance element operates. A control means that operates using the supplied DC voltage as the power supply voltage,
It has a generation means for generating a zero-cross signal indicating the zero-cross timing of the AC voltage.
The control means
A time measuring means for measuring the elapsed time based on the zero cross timing indicated by the zero cross signal, and
A stop determining means for determining that the supply of the AC voltage has stopped when the elapsed time exceeds the first threshold time, and
When the stop determination means determines that the supply of the AC voltage has stopped, the holding means for holding the log data indicating that the supply of the AC voltage has stopped, and the holding means.
If the control means is operating even if the elapsed time exceeds the second threshold time, the failure determination means for determining that the generation means has failed, and the failure determination means.
Have,
When the control means is operating even if the elapsed time exceeds the second threshold time, the control means provides log data indicating that the supply of the AC voltage held by the holding means has stopped. An image forming apparatus that is deleted and causes the holding means to hold log data indicating that a failure related to the generating means has occurred. A conversion means that converts AC voltage supplied from an AC power supply into DC voltage,
Capacitive elements charged by the DC voltage and
When the AC power supply supplies the AC voltage, the DC voltage generated by the conversion means is used as the power supply voltage, and when the supply of the AC voltage from the AC power supply is interrupted, the capacitance element operates. A control means that operates using the supplied DC voltage as the power supply voltage,
It has a generation means for generating a zero-cross signal indicating the zero-cross timing of the AC voltage.
The control means
If the zero cross signal is lost even though the AC power supply is not lost, it is determined that a failure related to the generation means has occurred.
An image forming apparatus, characterized in that it is configured to stop when the AC power source is lost and the supply of electric power from the capacitive element is interrupted. A conversion means that converts AC voltage supplied from an AC power supply into DC voltage,
Capacitive elements charged by the DC voltage and
A control means that operates using the DC voltage or the DC voltage supplied from the capacitive element as a power supply voltage, and
It has a generation means for generating a zero-cross signal indicating the zero-cross timing of the AC voltage.
The control means
A time measuring means for measuring the elapsed time based on the zero cross timing indicated by the zero cross signal, and
When the elapsed time exceeds the threshold time, a determination means for determining that a failure related to the generation means has occurred, and
Have,
The image forming apparatus, characterized in that the threshold time is longer than the operating time during which the control means can be continuously operated by the DC voltage supplied from the capacitive element after the supply of the AC voltage is stopped.

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