Power supply device and image forming apparatus

Abstract

To maintain an electrolytic capacitor open even when excessive voltage is applied to the electrolytic capacitor to prevent the occurrence of a defect that impairs the safety of a power supply device.SOLUTION: A power supply device has: a rectifier circuit that rectifies AC voltage and outputs the AC voltage to an output node; an electrolytic capacitor that is connected between the output node and a first voltage line; and a current monitoring cut-off circuit that is connected between the output node and the electrolytic capacitor or between the electrolytic capacitor and the first voltage line, monitors a current flowing through the electrolytic capacitor, and when a current equal to or larger than a threshold current flows, cuts off a path of the current flowing through the electrolytic capacitor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power supply device and an image forming apparatus.

Background Art

[0002] In a power supply device, there is known a technique of blocking a fuse connected to a commercial AC power supply and suppressing damage to components such as an electrolytic capacitor by flowing a current through components such as a transistor or a varistor when an excessive voltage is input from the commercial AC power supply (see, for example, Patent Documents 1 and 2).

Summary of the Invention

Problems to be Solved by the Invention

[0003] However, when a transistor, a varistor, or the like is damaged due to an excessive voltage input and the current cannot flow, the current fuse is not blocked, and thus an excessive voltage may be applied to the electrolytic capacitor. When an excessive voltage is applied to the electrolytic capacitor, not only the valve opening of the electrolytic capacitor occurs, but also the safety of the power supply device and the electronic device on which the power supply device is mounted may be impaired.

[0004] In view of the above problems, an object of the present invention is to keep the electrolytic capacitor in the valve opening state even when an excessive voltage is applied to the electrolytic capacitor, and to suppress the occurrence of a defect in which the safety of the power supply device is impaired.

Means for Solving the Problems

[0005] To solve the above technical problems, a power supply device according to an aspect of the present invention includes a rectifier circuit that rectifies an AC voltage and outputs it to an output node, an electrolytic capacitor connected between the output node and a first voltage line, and a connection between the output node and the electrolytic capacitor or between the electrolytic capacitor and the first voltage line, and monitors a current flowing through the electrolytic capacitor, and when a current equal to or greater than a threshold current flows, a current monitoring cutoff circuit that cuts off a path of the current flowing through the electrolytic capacitor.

Effects of the Invention

[0006] Even when an excessive voltage is applied to the electrolytic capacitor, the electrolytic capacitor can be kept open, and the occurrence of a defect that impairs the safety of the power supply device can be suppressed.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0008] Hereinafter, embodiments will be described with reference to the drawings. In each drawing, the same reference numerals are given to the same constituent parts, and redundant descriptions may be omitted. Hereinafter, the same reference numerals as the voltage name are used for the voltage lines through which the voltage is transmitted, and the same reference numerals as the signal name are used for the signal lines through which the signal is transmitted.

[0009] (First Embodiment) FIG. 1 is a block diagram showing an example of a power supply device according to a first embodiment of the present invention. For example, a power supply device 100 shown in FIG. 1 is a switching power supply that smooths an input voltage ACIN received from a commercial AC power supply via an input terminal and further converts the voltage to generate DC voltages V24 and V5. Although not particularly limited, the DC voltages V24 and V5 may be 24V and 5V, respectively. The power supply device 100 may be mounted on an electronic device such as an image forming apparatus, a projector, an electronic blackboard, a digital signage, an imaging device, a PC (Personal Computer), or a server, together with a load (not shown). The power supply device 100 includes a fuse 110, a rectifier circuit 120, a fuse 130, an electrolytic capacitor 140, and a DC / DC converter 150 (DC stands for Direct Current).

[0010] The fuse 110 is disposed between an input terminal that receives a voltage input line ACIN and the rectifier circuit 120, and protects the power supply device 100 from overcurrent by being cut off (fused) when a fusing current defined by the electrical specifications of the fuse flows. The fuse 110 is an example of a second fuse. Hereinafter, the fuse 110 connected to the voltage input line ACIN is also referred to as an input fuse.

[0011] The rectifier circuit 120 is, for example, a full-wave rectifier circuit including a diode bridge, rectifies an alternating input voltage ACIN, and outputs it as a DC voltage (pulsating current) to a voltage line V1. The voltage line V1 is an example of an output node. The electrolytic capacitor 140 generates a DC voltage V1 depending on the amplitude of the input voltage ACIN on the voltage line V1 by smoothing the voltage (pulsating current) output from the rectifier circuit 120. The DC / DC converter 150 generates DC voltages V24 and V5 based on the DC voltage V1, respectively.

[0012] The fuse 130 and the electrolytic capacitor 140 are connected in series between the voltage line V1 and the ground line GND. Note that the fuse 130 and the electrolytic capacitor 140 may be connected in series between the voltage line V1 and a low-voltage line with a fixed voltage value. The ground line GND is an example of a first voltage line. The fusing current of the fuse 130 is an example of a threshold current. Note that the fuse 130 and the electrolytic capacitor 140 may be connected in series between the voltage line V1 and the ground line GND in an order reverse to that in FIG. 1.

[0013] For example, after the electrolytic capacitor 140 has an open valve (open failure), when a short-circuit failure occurs, the fuse 130 is cut off (fused) to cut off the current path flowing through the electrolytic capacitor. Thereby, it is possible to prevent the electrolytic capacitor 140 from being only opened and the energization of the short-circuited electrolytic capacitor from continuing. The fuse 130 is an example of a first fuse, monitors the current flowing through the electrolytic capacitor 140, and is an example of a current monitoring cutoff circuit that cuts off the current path flowing through the electrolytic capacitor 140 when a current equal to or greater than the threshold current flows.

[0014] Note that the fusing current of the fuse 130 is smaller than the fusing current of the fuse 110. Thereby, the fuse 130 connected in series to the electrolytic capacitor 140 can be cut off before the fuse 110. Therefore, as will be described later, the electrolytic capacitor 140 can be kept open, and the flow of a large current through the electrolytic capacitor 140 due to a short-circuit failure can be immediately stopped.

[0015] For example, the fuse 130 does not cut off within the range of current defined by the required specifications such as the inrush current generated when the device in which the power supply device 100 is mounted is started, and cuts off when the leakage current of the electrolytic capacitor 140 increases due to overvoltage or when a short-circuit current occurs due to a short-circuit failure after the electrolytic capacitor 140 has an open valve. For example, the operating point of the cutoff of the fuse 130 may be set based on one or more of the input voltage range, the overcurrent operating point, the conversion efficiency, and the inrush current prevention circuit.

[0016] The input voltage range indicates the voltage value of the commercial AC power supply that can guarantee the operation according to the specifications in the power supply device 100. The lower the input voltage, the larger the current flowing through the electrolytic capacitor 140 during normal operation. It is necessary to select a fuse 130 that does not blow at the current value flowing during normal operation at the lower limit of the input voltage range.

[0017] The overcurrent operating point indicates the current value at which the output stop protection function works to prevent damage to the power supply device 100 and the image forming apparatus 1 in which the power supply device 100 is mounted. The higher the output current value, the larger the current flowing into the electrolytic capacitor 140. It is necessary to select a fuse 130 that does not blow even at the output current value immediately before the output stop protection function works.

[0018] The conversion efficiency indicates the ratio of the output power to the input power in the power supply device 100. The lower the conversion efficiency, the larger the current flowing into the electrolytic capacitor 140. It is necessary to select a fuse 130 that does not blow at the current value that may occur at the lowest efficiency specified by the specifications of the power supply device 100.

[0019] The inrush current prevention circuit is a circuit for suppressing the current (inrush current) that flows instantaneously when the power plug is connected to the outlet by a resistor or the like. The inrush current increases as the input voltage increases. Depending on the configuration (resistance value, etc.) of the inrush current prevention circuit, the short-circuit current value generated when the electrolytic capacitor 140 suffers a short-circuit failure changes. The fuse 130 must not blow at the inrush current generated at the upper limit of the input voltage range and must blow at the current value when the electrolytic capacitor 140 suffers a short-circuit failure due to an excessive voltage exceeding the input voltage range.

[0020] FIG. 2 is an overall configuration diagram showing an example of an image forming apparatus in which the power supply device 100 of FIG. 1 is mounted. The image forming apparatus 1 shown in FIG. 2 is, for example, a digital multi-function peripheral (MFP: Multi-Function Printer) having functions such as a copying function, a printing function, a scanner function, and a facsimile function. The image forming apparatus 1 can mutually switch operation modes for realizing a copying function, a printing function, a scanner function, and a facsimile function, respectively, by an application switching key or the like of an operation unit of the image forming apparatus 1. When the copying function is selected, the image forming apparatus 1 enters a copy mode, when the printing function is selected, it enters a print mode, when the scanner function is selected, it enters a scanner mode, and when the facsimile function is selected, it enters a facsimile mode.

[0021] Further, the image forming apparatus 1 switches its internal state to a normal mode, a power saving mode (power saving mode), or the like according to the state of the internal circuit. For example, the normal mode includes an operating mode (operating state) and a standby mode (standby state).

[0022] For example, the operating mode includes a copy mode or a print mode for printing an image or text data or the like on a paper medium or the like. The print mode includes an operation of printing received data on a paper medium or the like in the facsimile mode. Further, the operating mode includes a scanner mode for scanning an original or the like or a transmission / reception operation in the facsimile mode. The state of the internal circuit is switched by an operation of the operation unit by the user of the image forming apparatus 1 or control within the image forming apparatus 1.

[0023] For example, the image forming apparatus 1 includes an automatic document feeder 2 (ADF: Auto Document Feeder), an image reading device 3, a writing unit 4, a printer unit 5, an operation unit 11, a control board 200, and the power supply device 100 shown in FIG. 1. The printer unit 5 includes a photosensitive drum 6, a developing device 7, a transfer belt 8, a fixing device 9, and a storage space for storing a paper feed tray 10.

[0024] The power supply device 100 is connected to a commercial AC power supply via a power cable, and has a function of using the AC voltage supplied from the commercial AC power supply to generate, for example, the DC voltages V24 and V5 in FIG. 1 and supplying them as power to various loads in FIG. 2. Examples of loads to which power is supplied include an automatic document feeder 2, an image reading device 3, a writing unit 4, a printer unit 5, an operation unit 11, and a control board 200, etc.

[0025] The printer unit 5 creates a toner image to be transferred onto a paper medium or the like based on image information. The printer unit 5 is an example of an image forming unit that forms an image. Hereinafter, as an example of the flow of image formation in the image forming apparatus 1, the case where the operation mode is set to the copy mode will be briefly described.

[0026] In the copy mode, a stack of documents (multiple documents) to be copied is set in the automatic document feeder 2, or a document to be copied is set on the image reading device 3. When the start button displayed on the operation unit 11 is pressed, the automatic document feeder 2 feeds the documents one by one to the image reading device 3. The image reading device 3 reads the image information of each of the documents sequentially sent from the automatic document feeder 2 or the document set on the image reading device 3. The image information read by the image reading device 3 is processed, for example, by an image processing unit mounted on the control device 12.

[0027] The writing unit 4 converts the image information processed by the image processing unit into optical information. The photosensitive drum 6 is uniformly charged by a charger disposed at a position facing the photosensitive drum 6, and then exposed by a laser beam including the optical information converted by the writing unit 4. By the exposure, an electrostatic latent image is formed on the photosensitive drum 6. The developing device 7 develops the electrostatic latent image on the photosensitive drum 6 and forms a toner image on the photosensitive drum 6. The transfer belt 8 transfers the toner image onto a paper medium or the like. The fixing device 9 fixes the toner image onto a paper medium or the like. Then, the transfer paper on which the image of the document is copied is discharged from the discharge unit.

[0028] The operation unit 11 receives various inputs according to the operations of the user, and also displays various information on the display unit of the operation unit 11. For example, the information displayed on the operation unit 11 is information indicating the operation that has received the input, information indicating the operation status of the image forming apparatus 1, or information indicating the setting state of the image forming apparatus 1, etc. For example, the control board of the operation unit 11 receives the DC voltage from the power supply device and operates constantly. For this reason, the operation unit 11 can receive various inputs not only during the normal mode but also during the energy saving mode.

[0029] A CPU (not shown) mounted on the control board 200 controls the overall operation of the image forming apparatus 1, such as controlling the printer unit 5, controlling communication, and controlling the input to the operation unit 11, by executing an operation control program. Further, the CPU performs image processing or data processing by executing an image processing program or a data processing program, and forms an image to be transferred onto a paper medium or the like.

[0030] FIG. 2 shows an example in which the power supply device 100 is mounted on an image forming apparatus 1 such as a digital multifunction peripheral. However, the power supply device 100 may be mounted on an image forming apparatus having a single function such as a scanner, a printer, or a facsimile machine, for example.

[0031] FIG. 3 is a diagram showing an example of the current flowing through the electrolytic capacitor 140 and the voltage applied to the electrolytic capacitor 140 in the power supply device 100 of FIG. 1. For example, it is assumed that the power supply device 100 is mounted on the image forming apparatus 1 of FIG. 2.

[0032] First, the image forming apparatus 1 on which the power supply device 100 is mounted is activated, and the rectifier circuit 120 of the power supply device 100 starts generating a voltage (FIG. 3(a)). When a normal voltage within the specification range is applied from the rectifier circuit 120, a fuse 130, which is an example of a current monitoring cutoff circuit, is not cut off, and the power supply device 100 supplies the current necessary for the normal operation of the image forming apparatus 1 (FIG. 3(b)).

[0033] For example, when the image forming apparatus 1 is started up, an inrush current flows through the electrolytic capacitor 140 (Fig. 3(c)). In the standby state after startup and the standby state after printing, a steady current flows according to the DC voltage V1 used (Fig. 3(d)). While the image forming apparatus 1 is performing a printing operation, the current flowing through a load such as the printer unit 5 increases within the range of the steady current, and the current flowing through the electrolytic capacitor 140 also increases as the current increases.

[0034] On the other hand, when an input voltage ACIN with an excessive amplitude is supplied from the commercial AC power supply AC to the power supply device 100, an overvoltage is applied from the rectifier circuit 120 to the electrolytic capacitor 140 (Fig. 3(e)). If the overvoltage continues, the current flowing through the electrolytic capacitor 140 increases while generating heat in the electrolytic capacitor 140 (Fig. 3(f)).

[0035] Due to the heat generation of the electrolytic capacitor 140, when the electrolytic solution evaporates, the pressure inside the electrolytic capacitor 140 rises. When the pressure inside the electrolytic capacitor 140 reaches a predetermined pressure, the explosion-proof valve of the electrolytic capacitor 140 operates and the electrolytic capacitor opens, resulting in an open circuit failure (Fig. 3(g)).

[0036] Furthermore, if the application of the overvoltage from the rectifier circuit 120 to the electrolytic capacitor 140 continues and the foil inside the electrolytic capacitor 140 is deformed due to the increased pressure inside the electrolytic capacitor 140 or the like, a short circuit or insulation breakdown between the anode and the cathode occurs, and a short circuit failure occurs (Fig. 3(h)). When a short circuit failure occurs, the current flowing through the electrolytic capacitor 140 increases rapidly.

[0037] When the current flowing through the electrolytic capacitor 140 exceeds the fusing current of the fuse 130 and the current exceeding the fusing current continues for a predetermined time or more, the fuse 130 is cut off. As a result, even when a short circuit failure occurs, the energization path to the electrolytic capacitor 140 is cut off, and no current flows through the electrolytic capacitor 140 (Fig. 3(i)), and no overvoltage is applied to the electrolytic capacitor 140 (Fig. 3(j)). That is, the electrolytic capacitor 140 is only limited to opening the valve, and it is possible to suppress the occurrence of a problem that impairs the safety of the power supply device 100.

[0038] FIG. 4 is a diagram showing an example of the relationship between the voltage applied to the electrolytic capacitor and the operation of the power supply device. The left side of FIG. 4 shows an example of the operation when a control element such as a transistor is operated to cut off an input fuse arranged in the input section of the power supply device when an excessive voltage is applied. Hereinafter, operating the control element to cut off the input fuse is also referred to as turning on the control element. The right side of FIG. 4 shows an example of the operation in the power supply device of FIG. 1 when a current larger than normal flows through the electrolytic capacitor 140 and the fuse 130 is cut off when an excessive voltage is applied.

[0039] In the control by the control element shown on the left side of FIG. 4, the maximum voltage at which the power supply device operates normally is set lower than the voltage at which the electrolytic capacitor opens its valve. For this reason, the voltage range in which the operating voltage of the control element varies becomes a voltage range in which the electrolytic capacitor does not open its valve but the power supply device stops. This voltage range is set below the lower limit value of the variation in the valve-opening voltage of the electrolytic capacitor due to manufacturing variations of the electrolytic capacitor 140. Therefore, even if the voltage applied to the electrolytic capacitor is lower than the actual valve-opening voltage, the input fuse melts due to the turning on of the control element, and the power supply device stops. As a result, the frequency of service calls due to the stop of the power supply device increases, and the repair frequency or replacement frequency of the power supply device that should normally operate increases. In addition, the machine downtime due to the repair or replacement of the power supply device increases, and the maintenance cost increases.

[0040] Note that the voltage for turning on the control element is set in accordance with the electrolytic capacitor having the lowest valve-opening voltage. For example, the electrolytic capacitor having the lowest valve-opening voltage may be obtained by actually measuring the valve-opening voltages of a plurality of electrolytic capacitors. Also, the voltage for turning on the control element may be set in consideration of manufacturing variations of the control element.

[0041] On the left side of FIG. 4, in a voltage region exceeding the on-voltage of the control element, the fuse is cut off when the control element turns on, and the voltage is not applied to the electrolytic capacitor, so that the valve opening of the electrolytic capacitor can be suppressed. However, when a voltage exceeding the voltage rating of the control element is applied to the control element, there is a risk of an open fault occurring in the control element. Since the control element with an open fault does not conduct current, the input fuse is not cut off. As a result, there is a risk that an overvoltage continues to be applied to the electrolytic capacitor, and the electrolytic capacitor may open its valve. Furthermore, when an overvoltage continues to be applied to the electrolytic capacitor even after the valve has opened, there is a risk that it will not stop at just opening the valve.

[0042] In the control by the fuse 130 shown on the right side of FIG. 4, instead of detecting the value of the overvoltage itself, the overvoltage is indirectly detected by the fuse 130 being cut off by the current that increases when the overvoltage is applied to the electrolytic capacitor 140. Since the electrical resistance value of the fuse 130 is low, even when an overvoltage is applied to one end of the fuse 130, the voltage difference generated across the fuse 130 is almost zero, and the fuse 130 is not damaged by the overvoltage.

[0043] Then, when the fuse 130 is cut off, the application of an overvoltage to the electrolytic capacitor 140 is suppressed, and even when a short circuit fault occurs in the electrolytic capacitor 140, the continuation of energization to the electrolytic capacitor 140 can be suppressed. In other words, on the right side of FIG. 4, the valve opening of the electrolytic capacitor 140 can be restricted, and the occurrence of problems that may impair the safety of the power supply device 100 and devices such as the image forming apparatus 1 in which the power supply device 100 is mounted can be suppressed.

[0044] Also, even when the breakdown voltage of the electrolytic capacitor 140 varies, the power supply device 100 can operate normally until the electrolytic capacitor 140 actually breaks down. Therefore, the frequency of the power supply device 100 stopping can be made lower compared to the left side of FIG. 4, and it is possible to prevent the power supply device 100 that originally operates normally from being replaced. As a result, an increase in machine downtime due to repair or replacement of the power supply device 100 can be suppressed, and an increase in maintenance costs can be suppressed.

[0045] As described above, in the first embodiment, the fuse 130 blocks the current path flowing through the electrolytic capacitor by being cut off when a short circuit failure occurs after the electrolytic capacitor 140 breaks down (open failure). Thereby, even when an excessive voltage is applied to the electrolytic capacitor 140, the electrolytic capacitor 140 can be kept from breaking down, and it is possible to suppress the occurrence of problems that would impair the safety of the power supply device 100 and systems such as the image forming apparatus 1 on which the power supply device 100 is mounted. At this time, by using the fuse 130, which is a passive component rather than an active element having a control terminal such as a transistor, it is possible to suppress the occurrence of problems that would impair the safety of the power supply device 100 and the system with a simple circuit without using a control signal.

[0046] Also, even when the breakdown voltage of the electrolytic capacitor 140 varies, the power supply device 100 can operate normally until the electrolytic capacitor 140 actually breaks down. Therefore, the frequency of the power supply device 100 stopping can be made lower, and it is possible to prevent the power supply device 100 that originally operates normally from being replaced. As a result, an increase in machine downtime due to repair or replacement of the power supply device 100 can be suppressed, and an increase in maintenance costs can be suppressed.

[0047] The fusing current of the fuse 130 is smaller than the fusing current of the fuse 110. This makes it possible to cause the fuse 130 connected in series with the electrolytic capacitor 140 to be cut off before the fuse 110. Therefore, the electrolytic capacitor 140 can be kept from breaking down, and a large current flowing through the electrolytic capacitor 140 due to a short circuit failure can be immediately stopped.

[0048] (Second Embodiment) FIG. 5 is a block diagram showing an example of a power supply device according to a second embodiment of the present invention. The same elements as those in FIG. 1 are denoted by the same reference numerals, and detailed descriptions thereof are omitted. The power supply device 100A shown in FIG. 5 has the same configuration and functions as the power supply device 100 in FIG. 1, except that it has a current monitoring cutoff circuit 130A instead of the fuse 130. The current monitoring cutoff circuit 130A and the electrolytic capacitor 140 are connected in series between the voltage line V1 and a voltage line with a fixed low voltage such as the ground line GND.

[0049] The current monitoring cutoff circuit 130A has a current monitoring circuit 132 and a current cutoff circuit 134 connected in series between the power supply line V1 and the electrolytic capacitor 140. For example, the current cutoff circuit 134 may be a transistor such as a FET (Field Effect Transistor). Note that the current monitoring cutoff circuit 130A and the electrolytic capacitor 140 may be connected in series between the voltage line V1 and the ground line GND in the reverse order of FIG. 5. Also, the current monitoring circuit 132 and the current cutoff circuit 134 may be connected to the electrolytic capacitor 140 in the reverse order of FIG. 5.

[0050] The current monitoring circuit 132 monitors the current flowing through the electrolytic capacitor 140 and controls the on / off of the current cutoff circuit 134. When the current is less than the threshold current that flows during a short circuit failure of the electrolytic capacitor 140, the current monitoring circuit 132 maintains the on state of the current cutoff circuit 134 and maintains the connection between the voltage line V1 and the electrolytic capacitor 140. When the current becomes equal to or greater than the threshold current, the current monitoring circuit 132 turns off the current cutoff circuit 134 and cuts off the path of the current flowing from the voltage line V1 to the electrolytic capacitor 140. Thereby, the same control as the current control during the short circuit failure shown in FIG. 3 can be realized.

[0051] [[ID=1J6]] As described above, in the second embodiment, the same effects as those in the first embodiment can be obtained even when the current monitoring cutoff circuit 130A having the current monitoring circuit 132 and the current cutoff circuit 134 is connected to the electrolytic capacitor 140.

[0052] Although the present invention has been described based on each embodiment above, the present invention is not limited to the requirements shown in the above embodiments. Regarding these points, it can be changed without departing from the gist of the present invention and can be appropriately determined according to its application form.

Explanation of Reference Numerals

[0053] 1 Image forming apparatus 2 Automatic document feeder 3 Image reading device 4 Writing unit 5 Printer unit 6 Photoconductor drum 7 Developing device 8 Transfer belt 9 Fixing device 10 Paper feed tray 11 Operation unit 100 Power supply device 110 Fuse 120 Rectifier circuit 130 Fuse 130A Current monitoring and cutoff circuit 132 Current monitoring circuit 134 Current cutoff circuit 140 Electrolytic capacitor 150 DC / DC converter 200 Control board AC Commercial AC power supply ACIN Input voltage V1 Voltage line, DC voltage V5, V2 DC voltage

Prior Art Documents

Patent Documents

[0054]

Patent Document 1

Patent Document 2

Claims

1. a rectifier circuit that rectifies the AC voltage and outputs the rectified AC voltage to an output node; an electrolytic capacitor connected between the output node and a first voltage line; a current monitoring and interrupting circuit connected between the output node and the electrolytic capacitor or between the electrolytic capacitor and the first voltage line, monitoring the current flowing through the electrolytic capacitor, and interrupting the path of the current flowing through the electrolytic capacitor when a current equal to or greater than a threshold current flows. A power supply device comprising:

2. The current monitoring and interrupting circuit is a first fuse.

2. The power supply device according to claim 1,

3. an input terminal for receiving the AC voltage; a second fuse connected between the input terminal and the input of the rectifier circuit; The fusing current of the first fuse is smaller than the fusing current of the second fuse.

3. The power supply device according to claim 2, wherein:

4. The current monitoring and interrupting circuit a current monitoring circuit that monitors the current flowing through the electrolytic capacitor; a current interruption circuit that interrupts a path of current flowing through the electrolytic capacitor when the current monitoring circuit detects a current equal to or greater than the threshold current.

2. The power supply device according to claim 1,

5. The power supply device according to any one of claims 1 to 4, an image forming unit that forms an image based on the voltage generated by the power supply device; An image forming apparatus comprising:

Images