JP7746838B2 - Power supply control device, image forming apparatus and power supply control method - Google Patents

Description

The present invention relates to a power supply control device, an image forming device, and a power supply control method.

In power supply devices, a technology is known that prevents the smoothing electrolytic capacitor from opening due to an overvoltage by activating a protection circuit to cut off the current path when an overvoltage occurs in the input AC voltage (see, for example, Patent Document 1).

With this type of technology, the protection circuit operates when the effective AC voltage exceeds a threshold, regardless of the load state. When setting the threshold for the effective voltage without taking the load state into account, the threshold is set to a low value to ensure safety and allow the protection circuit to operate with ample margin. This has led to the problem of the protection circuit operating even under conditions where there is no possibility of the electrolytic capacitor opening. This has resulted in unnecessary downtime and/or the cost of unnecessary repair services.

In light of the above issues, the present invention aims to prevent electrolytic capacitors installed in power supply circuits from opening, while reducing the frequency of downtime and the cost of repair services.

In order to solve the above technical problems, one form of the present invention provides a power supply control device that controls a power supply device having a rectifier unit that includes an electrolytic capacitor and converts AC voltage to DC voltage, a voltage generation unit that converts the DC voltage to a predetermined voltage to be supplied to a load device, and a power cut-off unit that cuts off the supply of AC voltage to the rectifier unit in response to a cut-off signal. The power supply control device is characterized by having a voltage detection unit that detects the voltage value of the DC voltage or the AC voltage, a threshold holding unit that holds multiple voltage thresholds corresponding to multiple operating modes of the load device, and a control unit that selects, from the multiple voltage thresholds held in the threshold holding unit, a voltage threshold that corresponds to the operating mode currently in operation, and outputs the cut-off signal when the voltage value detected by the voltage detection unit is equal to or greater than the selected voltage threshold.

This prevents electrolytic capacitors installed in the power supply circuit from opening, while reducing the frequency of downtime and the cost of repair services.

1 is a diagram illustrating the overall configuration of an image forming apparatus according to an embodiment of the present invention. 2 is a block diagram showing an outline of the power supply device of FIG. 1 and a load to which a DC voltage is supplied from the power supply device; 3 is an explanatory diagram showing an example of specifications of voltage thresholds stored in the threshold table of FIG. 2; FIG. 4 is an explanatory diagram showing an example of the relationship between the voltage threshold value in FIG. 3 and the valve-opening voltage in each operation mode. FIG. 3 is a state transition diagram showing the transition of operation modes of the image forming apparatus of FIG. 2. 3 is an explanatory diagram showing an example of timing for changing the operation mode of the image forming apparatus shown in FIG. 2 and the voltage threshold value. 3 is a flowchart showing an example of control of a power cutoff unit by the controller of FIG. 2. FIG. 8 is a flowchart showing an example of the process of step S200 in FIG. 7. 4 is a flowchart showing an example of setting a voltage threshold value by a threshold value changing unit when the image forming apparatus of FIG. 2 is powered on; FIG. 3 is a block diagram showing an example of a hardware configuration of a controller shown in FIG. 2 . FIG. 10 is a block diagram showing an outline of another power supply device and a load to which a DC voltage is supplied from the other power supply device.

Embodiments will be described below using the drawings. Below, symbols indicating signals are also used to indicate signal values or signal lines. Symbols indicating voltages are also used to indicate voltage values or voltage lines through which voltages are supplied.

Figure 1 is a diagram showing the overall configuration of an image forming apparatus according to one embodiment of the present invention. The image forming apparatus 1 shown in Figure 1 is, for example, a digital multifunction peripheral (MFP: Multi-Function Printer) with copy, print, scanner, and facsimile functions. The image forming apparatus 1 can switch between operating modes that respectively realize the copy, print, scanner, and facsimile functions using an application switching key or the like on an operation unit (not shown). The image forming apparatus 1 enters copy mode when the copy function is selected, print mode when the print function is selected, scanner mode when the scanner function is selected, and facsimile mode when the facsimile function is selected. Note that the image forming apparatus 1 may also be a copier with only a copy function, a printer with only a print function, or a facsimile with only a facsimile function.

In addition, the image forming device 1 switches its internal state between an operating mode (operating state), a standby mode (standby state), an energy-saving mode (low-power state), etc., depending on the state of its internal circuits. Hereinafter, the energy-saving mode will also be referred to as the energy-saving mode.

For example, the operating mode includes a copy mode or a print mode in which images or text data are printed on paper media. The print mode includes an operation in facsimile mode in which received data is printed on paper media. The operating mode also includes a scanner mode in which documents are scanned, or a transmission/reception operation in facsimile mode. The state of the internal circuitry is switched by the user operating the operation unit or by control within the image forming device 1.

For example, image forming device 1 has an automatic document feeder (ADF) 2, an image reading device 3, a writing unit 4, a printer unit 5, and a power supply device 20. Printer unit 5 has a photosensitive drum 6, a developing device 7, a conveyor belt 8, a fixing device 9, and a storage space for a paper feed tray 10. Printer unit 5 creates a toner image to be transferred to paper media, etc., based on image information. Below, we will briefly explain an example of the flow of image formation in image forming device 1 when the operating mode is set to copy mode.

In copy mode, multiple originals to be copied are placed in the automatic document feeder 2. When the start button on the operation panel (not shown) is pressed, the automatic document feeder 2 feeds the originals one by one to the image reading device 3. The image reading device 3 reads the image information of each original sent in turn from the automatic document feeder 2. The image information read by the image reading device 3 is processed by an image processing unit (not shown).

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 (not shown) and then exposed to laser light containing the optical information converted by the writing unit 4. An electrostatic latent image is formed on the photosensitive drum 6 through exposure. The developing device 7 develops the electrostatic latent image on the photosensitive drum 6, forming a toner image on the photosensitive drum 6. The conveyor belt 8 transfers the toner image to a paper medium or the like. The fixing device 9 fixes the toner image to the paper medium or the like. The transfer paper on which the original image has been copied is then discharged from the discharge section.

For example, the standby mode described above is the state in copy mode until the start button is pressed, and the operating mode is the state from when the start button is pressed until paper media or the like is ejected, in which loads such as motors are operating. After the operating mode ends, the image forming device 1 returns to standby mode, and if standby mode continues for a predetermined time, it enters energy-saving mode. Then, if the operating unit is operated during energy-saving mode, the image forming device 1 returns to standby mode.

The power supply device 20 converts AC voltage supplied from an AC power supply 30, such as a commercial power source, into DC voltage and supplies the converted DC voltage to various loads, such as the printer unit 5 of the image forming device 1. For example, the loads include various motors, a charger that charges the photosensitive drum 6, and the developing roller of the developing device 7. The image forming device 1 may have multiple power supply devices 20, one for each charger and developing roller.

Figure 2 is a block diagram showing an outline of the power supply device 20 of Figure 1 and a load to which DC voltage is supplied from the power supply device 20. The power supply device 20 has a diode bridge 21, an aluminum electrolytic capacitor 22, a converter unit 23, a voltage detection unit 24, a temperature detection unit 25, a power cut-off unit 26, and a fuse 27.

The diode bridge 21 full-wave rectifies the AC voltage supplied from the AC power supply 30 and outputs the full-wave rectified voltage to the converter unit 23. The aluminum electrolytic capacitor 22 is connected between the diode bridge 21 and the converter unit 23 and smooths the full-wave rectified voltage to generate a DC voltage. The diode bridge 21 and aluminum electrolytic capacitor 22 are an example of a rectifier unit. Note that the power supply device 20 may also include electrolytic capacitors other than the aluminum electrolytic capacitor 22.

The converter unit 23 generates a DC voltage, such as 5V or 24V, corresponding to the operating voltage of the load 40 from the smoothed DC voltage, and supplies the generated DC voltage to the load 40. Note that the value of the DC voltage generated by the converter unit 23 may be other than 5V or 24V. The converter unit 23 is an example of a voltage generation unit.

For example, the load 40 includes a 24V load and a 5V load. The 24V load includes the charger 41 that charges the photosensitive drum 6 shown in FIG. 1, various motors 42 in the printer unit 5, and the developing device 7 shown in FIG. 1. The 12V load includes the controller 50 that controls the overall operation of the image forming apparatus 1. The controller 50 is an example of a control unit. The load 40 is an example of a load device. The charger 41, motor 42, and developing device 7 included in the load 40 are an example of an image forming unit that forms an image.

The controller 50 controls the entire image forming apparatus 1, for example, by executing a program. The controller 50 has a threshold change unit 52 and a threshold table 54. For example, the threshold table 54 is stored in the internal memory of the controller 50, but it may also be stored in an external memory connected to the outside of the controller 50.

The controller 50 may be in the form of a motherboard, or in the form of a CPU (Central Processing Unit) that executes programs such as a power supply control program. Furthermore, the controller 50 may be in the form of a SoC (System on a Chip) that includes a CPU that executes programs such as a power supply control program, or in the form of an ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array).

The voltage detection unit 24 detects the voltage applied to the aluminum electrolytic capacitor 22 and notifies the controller 50 of the detected voltage value. In FIG. 2, the voltage detection unit 24 is connected to the output of the diode bridge 21 and detects the DC voltage applied to the aluminum electrolytic capacitor 22. The voltage detection unit 24 may also be mounted on the controller 50. In this case, for example, the DC voltage applied to the aluminum electrolytic capacitor 22 is connected to an analog input terminal provided on the controller 50.

The DC voltage applied to the aluminum electrolytic capacitor 22 varies depending on voltage fluctuations in the AC power supply 30. For this reason, the power supply device 20 may have, instead of the voltage detection unit 24, a voltage detection unit that is connected to the input of the power supply cutoff unit 26 and directly detects the AC voltage of the AC power supply 30.

The temperature detection unit 25 detects the ambient temperature of the aluminum electrolytic capacitor 22, for example, based on a temperature information signal output from a temperature sensor (not shown) installed in close proximity to the aluminum electrolytic capacitor 22. The temperature detection unit 25 may also be mounted on the controller 50. In this case, for example, the temperature information signal output from the temperature sensor is connected to an analog input terminal provided on the controller 50. Furthermore, if the voltage threshold VT is not changed in accordance with temperature by the threshold change unit 52 (described below), the temperature detection unit 25 may not be provided.

The power supply cutoff unit 26 connects the AC power supply 30 and the diode bridge 21 while not receiving a cutoff signal OFF from the controller 50. The power supply cutoff unit 26 cuts off the connection between the AC power supply 30 and the diode bridge 21 while receiving a cutoff signal OFF from the controller 50. The controller 50 outputs the cutoff signal OFF in accordance with the voltage value detected by the voltage detection unit 24. Hereinafter, the cutoff of the connection between the AC power supply 30 and the diode bridge 21 by the power supply cutoff unit 26 is also simply referred to as power cutoff.

Commercial power supplied from external power equipment may output abnormal overvoltage depending on the performance, reliability, or installation environment of the power equipment. If an abnormal overvoltage exceeding the withstand voltage specification is applied to aluminum electrolytic capacitor 22, there is a risk that the aluminum electrolytic capacitor 22 will open. In this embodiment, the shutoff operation of power supply shutoff unit 26 can prevent abnormal overvoltage exceeding the withstand voltage specification from being applied to aluminum electrolytic capacitor 22, thereby preventing the aluminum electrolytic capacitor 22 from opening.

The fuse 27 is disposed between the AC power supply 30 and the power cutoff unit 26. The fuse 27 is, for example, a thermal fuse or a resistor with a built-in thermal fuse.

When the voltage value detected by the voltage detection unit 24 is equal to or greater than a predetermined voltage threshold VT, the controller 50 outputs a shutdown signal OFF, causing the power shutdown unit 26 to shut off the power. The voltage threshold VT is a voltage value that triggers the controller 50 to output the shutdown signal OFF. The threshold change unit 52 changes the voltage threshold VT depending on the operating mode of the image forming apparatus 1. That is, the controller 50 selects a voltage threshold VT corresponding to the operating mode in operation from the threshold table 54, and outputs the shutdown signal OFF when the voltage value detected by the voltage detection unit 24 is equal to or greater than the selected voltage threshold VT. The threshold table 54 holds the voltage threshold VT for each operating mode. The threshold table 54 is an example of a threshold holding unit.

If a temperature detection unit 25 is provided, the threshold table 54 may store multiple voltage thresholds corresponding to predetermined temperature ranges, one for each of multiple operating modes. In this case, the controller 50 outputs a shutdown signal OFF when the voltage value detected by the voltage detection unit 24 is equal to or greater than the voltage threshold VT for each operating mode stored in the threshold table 54 in correspondence with the current temperature. If a temperature detection unit 25 is not provided, the controller 50 outputs a shutdown signal OFF when the voltage value detected by the voltage detection unit 24 is equal to or greater than the voltage threshold VT stored in the threshold table 54 in correspondence with the operating mode.

The voltage detection unit 24 and the controller 50, or the voltage detection unit 24, the temperature detection unit 25, and the controller 50, are examples of a power supply control device that realizes a power supply control method. Note that the voltage detection unit 24, the temperature detection unit 25, and the controller 50 that function as a power supply control device that realizes a power supply control method are not limited to the image forming apparatus 1. For example, the voltage detection unit 24, the temperature detection unit 25, and the controller 50 that function as a power supply control device may include an electrolytic capacitor and be installed in an electronic device such as a PC (Personal Computer) or a television set, whose load varies depending on its operation.

Figure 3 is an explanatory diagram showing an example of the specifications of the voltage thresholds VT stored in the threshold table 54 of Figure 2. The threshold table 54 stores, for example, three voltage thresholds VT (VT1, VT2, VT3) corresponding to three operating modes. The magnitude relationship among the three voltage thresholds VT is VT3 > VT2 > VT1.

Voltage threshold VT1 is used by the controller 50 to determine whether an overvoltage has occurred during active mode (copy mode or print mode). Voltage threshold VT2 is used by the controller 50 to determine whether an overvoltage has occurred during standby mode. Voltage threshold VT1 is used by the controller 50 to determine whether an overvoltage has occurred during energy saving mode.

The voltage threshold VT1 may be used by the controller 50 to determine whether an overvoltage has occurred during scanning in scanner mode or during transmission/reception in facsimile mode. In this case, the scanner mode and facsimile mode are also included in the active mode.

Active mode, standby mode, and energy saving mode impose increasing loads and consume greater power in that order. The load of a scanning operation in scanner mode or a sending/receiving operation in facsimile mode is less than the load of a copying mode or a printing mode, but greater than the load of standby mode. Therefore, another voltage threshold VT may be set between voltage threshold VT1 and voltage threshold VT2 to be used by the controller 50 to determine whether an overvoltage has occurred during a scanning operation in scanner mode or a sending/receiving operation in facsimile mode.

Figure 4 is an explanatory diagram showing an example of the relationship between the voltage thresholds in Figure 3 and the valve-opening voltage VT in each operating mode. The voltage threshold VT1 is set to a value that is a predetermined margin lower than the design value (assumed value) of the valve-opening voltage in active mode.

The voltage threshold VT2 is set to a value that is lower by a predetermined margin than the design value (estimated value) of the valve opening voltage in standby mode, and is higher than the design value (estimated value) of the valve opening voltage in copy/print mode. The voltage threshold VT3 is set to a value that is lower by a predetermined margin than the design value (estimated value) of the valve opening voltage in energy saving mode, and is higher than the design value (estimated value) of the valve opening voltage in standby mode.

For example, in energy saving mode, if the voltage detection unit 24 detects a voltage lower than the voltage threshold VT3, the controller 50 does not output a shutoff signal OFF, but if it detects a voltage equal to or greater than the voltage threshold VT3, it outputs a shutoff signal OFF. In contrast, for example, regardless of the operating mode, the power supply is shut off when a voltage equal to or greater than the voltage threshold VT1, which corresponds to the minimum expected value of the valve-opening voltage, is detected. In this case, in energy saving mode, the power supply is shut off when a voltage between the voltage thresholds VT1 and VT3, which does not normally require shutting off the power supply, is detected. Similarly, in standby mode, the power supply is shut off when a voltage between the voltage thresholds VT1 and VT2, which does not normally require shutting off the power supply, is detected.

In this embodiment, by setting a higher voltage threshold VT for operating modes with higher expected valve-opening voltages, it is possible to prevent unnecessary power cutoff at voltages that do not pose a risk of opening the aluminum electrolytic capacitor 22. As a result, it is possible to prevent unnecessary downtime and unnecessary repair service costs.

The voltage thresholds VT (VT11-VT13, VT21-VT23, VT31-VT33) shown in parentheses are examples of voltage thresholds VT stored in the threshold table 54 when the temperature detection unit 25 is provided. The symbols T1 and T2 indicate temperatures, with temperature T1 being higher than temperature T2 (T1>T2). Thus, when the temperature detection unit 25 is provided, the threshold change unit 52 selects one of three voltage thresholds VT according to the three temperature ranges in each of the active mode, standby mode, and energy-saving mode, and controls the generation of the shutdown signal OFF.

For example, in active mode, if the temperature detected by the temperature detection unit 25 in Figure 2 is equal to or higher than T1, the voltage threshold VT11 is selected. If the temperature detected by the temperature detection unit 25 is lower than T1 and equal to or higher than T2, the voltage threshold VT12 is selected. If the temperature detected by the temperature detection unit 25 is lower than T2, the voltage threshold VT13 is selected. Note that the number of voltage thresholds VT corresponding to the temperature for each operating mode is not limited to three, and may be two or four or more.

When an overvoltage is applied, the aluminum electrolytic capacitor 22 generates heat and opens, making it more likely to open the valve. Therefore, by lowering the voltage threshold VT (changing it to the safe side) when the ambient temperature is high, the aluminum electrolytic capacitor 22 can be appropriately prevented from opening depending on the operating mode and ambient temperature. This reduces unnecessary downtime and the cost of unnecessary repair services.

Figure 5 is a state transition diagram showing the transitions between operating modes of the image forming apparatus 1 in Figure 2. When the image forming apparatus 1 detects transition trigger information indicating a transition to standby mode while in energy saving mode, it transitions to standby mode. When it detects transition trigger information indicating a transition to active mode, it transitions to active mode. In energy saving mode, the controller 50 controls the power cut-off unit 26 using the voltage threshold VT3. If the temperature detection unit 25 is provided, voltage thresholds VT31-VT33 are used.

When the image forming apparatus 1 detects transition trigger information indicating a transition to energy saving mode while in standby mode, it transitions to energy saving mode. When it detects transition trigger information indicating a transition to active mode, it transitions to active mode. In standby mode, the controller 50 controls the power cut-off unit 26 using the voltage threshold VT2. If the temperature detection unit 25 is provided, the voltage thresholds VT21-VT23 are used.

When the image forming device 1 detects transition trigger information indicating a transition to energy saving mode during active mode, it transitions to energy saving mode. When the image forming device 1 detects transition trigger information indicating a transition to standby mode, it transitions to standby mode. In active mode, the controller 50 controls the power cut-off unit 26 using voltage threshold VT1. If the temperature detection unit 25 is provided, voltage thresholds VT11-VT13 are used.

Figure 6 is an explanatory diagram showing an example of the timing of the transition of operating modes and the change of the voltage threshold VT of the image forming apparatus 1 in Figure 2. Note that Figures 6 to 8 show an example in which the temperature detection unit 25 is not provided. If the temperature detection unit 25 is provided, the voltage thresholds VT1, VT2, and VT3 become the voltage thresholds VT11-VT13, VT21-VT23, and VT31-VT33 in Figure 4 depending on the temperature detected by the temperature detection unit 25.

As explained in Figure 4, the voltage thresholds VT1, VT2, and VT3 are set to values that are a predetermined margin lower than the expected valve-opening voltage corresponding to the load. The relationship between each voltage threshold VT1, VT2, and VT3 and each valve-opening voltage must be maintained not only during the operating mode, but also when the operating mode is switched.

For this reason, if the value of the voltage threshold VT to be selected increases due to a transition in the operating mode, the threshold change unit 52 selects the voltage threshold VT at the time the operating mode transition occurs, and sets this as the voltage threshold VT for determining whether to output the cutoff signal OFF. Also, if the value of the voltage threshold VT to be selected decreases due to a transition in the operating mode, the threshold change unit 52 selects the voltage threshold VT at the time the transition in the operating mode is determined by the transition trigger information, and sets this as the voltage threshold VT for determining whether to output the cutoff signal OFF.

For example, when transitioning from active mode to standby mode, the threshold change unit 52 detects transition trigger information and changes the voltage threshold from VT1 to VT2 at the timing when the operating mode transitions to standby mode (Figure 6(a)). When transitioning from standby mode to energy-saving mode, the threshold change unit 52 detects transition trigger information and changes the voltage threshold from VT2 to VT3 at the timing when the operating mode transitions to energy-saving mode (Figure 6(b)).

When transitioning from energy saving mode to active mode, the threshold change unit 52 changes the voltage threshold from VT3 to VT1 based on the detection of transition trigger information (Figure 6(c)). When transitioning from active mode to energy saving mode, the threshold change unit 52 changes the voltage threshold from VT1 to VT3 at the timing when the operating mode transitions to energy saving mode after detecting the transition trigger information (Figure 6(d)).

When transitioning from energy saving mode to standby mode, the threshold change unit 52 changes the voltage threshold from VT3 to VT2 based on the detection of transition trigger information (Figure 6(e)). When transitioning from standby mode to active mode, the threshold change unit 52 changes the voltage threshold from VT2 to VT1 based on the detection of transition trigger information (Figure 6(f)).

Figure 7 is a flow diagram showing an example of control of the power cut-off unit 26 by the controller 50 of Figure 2. The operation shown in Figure 7 may be realized by the hardware of the controller 50, by a CPU installed in the controller 50 executing a power control program, or by a combination of hardware and software. For example, the operation shown in Figure 7 is initiated after the process shown in Figure 9, described below, is executed when the power to the image forming apparatus 1 is turned on.

First, in step S102, the controller 50 determines whether transition trigger information indicating a transition of the operating mode has been detected. If the controller 50 detects transition trigger information, it proceeds to step S104; if the controller 50 does not detect transition trigger information, it executes step S102 again. For example, transition trigger information is generated within the image forming device 1 by an instruction to start copying, receipt of a print job, completion of a print job, or cancellation of the energy saving mode, etc.

For example, the energy saving mode is cancelled when the touch panel provided on the image forming device 1 is operated, or when the automatic document feeder 2 is lifted up to expose the platen glass for image scanning. Furthermore, the transition to standby mode occurs after printing on paper media is completed.

In step S104, the controller 50 determines whether the transition trigger information indicates a transition to active mode. If the transition trigger information indicates a transition to active mode, the controller 50 transitions processing to step S110. If the transition trigger information does not indicate a transition to active mode, the controller 50 transitions processing to step S106.

In step S106, the controller 50 determines whether the transition trigger information indicates a transition to standby mode. If the transition trigger information indicates a transition to standby mode, the controller 50 transitions to step S112. If the transition trigger information does not indicate a transition to standby mode, the controller 50 determines that the transition is to energy saving mode, and transitions to step S114.

In step S110, the controller 50 references the threshold table 54, determines the threshold voltage to be changed to the voltage threshold VT1 corresponding to the active mode, and proceeds to step S200. In step S112, the controller 50 references the threshold table 54, determines the threshold voltage to be changed to the voltage threshold VT2 corresponding to the standby mode, and proceeds to step S200.

In step S114, the controller 50 references the threshold table 54, determines the threshold voltage to be changed to the voltage threshold VT3 corresponding to the energy saving mode, and proceeds to step S200. Note that the controller 50 determines the voltage threshold to be changed in steps S110, S112, and S114, but changes to the determined voltage threshold are implemented by the processing in step S200.

In step S200, the controller 50 performs the voltage threshold change process and ends the process shown in FIG. 7. After this, the controller 50 controls the power cut-off unit 26 by controlling the generation of the cut-off signal OFF using the voltage threshold corresponding to the operating mode.

Figure 8 is a flow diagram showing an example of the processing of step S200 in Figure 7. First, in step S202, the controller 50 determines whether the current voltage threshold is VT1. If the current voltage threshold is VT1, the controller 50 proceeds to step S208. If the current voltage threshold is not VT1, the controller 50 proceeds to step S204.

In step S204, the controller 50 determines whether the current voltage threshold is VT2. If the current voltage threshold is VT2, the controller 50 proceeds to step S206. If the current voltage threshold is not VT2, the controller 50 proceeds to step S210 because the current voltage threshold is VT3.

In step S206, the controller 50 determines whether the changed voltage threshold is VT1. If the changed voltage threshold is VT1, the controller 50 proceeds to step S210. If the changed voltage threshold is not VT1, the controller 50 proceeds to step S208.

In step S208, after the transition of the operating mode, the controller 50 sets the voltage threshold to VT2 or VT3, and ends the processing shown in FIG. 6. In step S210, before the transition of the operating mode, the controller 50 sets the voltage threshold to VT1 or VT2, and ends the processing shown in FIG. 8. This enables the voltage threshold VT change operation shown in FIG. 6 to be realized.

Figure 9 is a flow diagram showing an example of setting the voltage threshold by the threshold change unit 52 when the image forming apparatus 1 in Figure 2 is powered on. The operation shown in Figure 9 begins when the image forming apparatus 1 is powered on and the converter unit 23 starts generating a 5V DC voltage.

First, the controller 50 determines whether or not trigger information indicating power-on has been detected. If the controller 50 detects trigger information indicating power-on, it proceeds to step S304; if it does not detect trigger information indicating power-on, it executes step S302 again. For example, trigger information indicating power-on is generated within the image forming apparatus 1 based on the power switch being turned on.

In step S304, the controller 50 sets the lowest voltage threshold among the voltage thresholds VT1-VT3 to VT1, and ends the processing shown in FIG. 7. Note that if a temperature detection unit 25 is provided, the controller 50 may set the voltage threshold VT11 in FIG. 4 in step S304.

When the image forming apparatus 1 is started, various elements within the image forming apparatus 1 begin operating, increasing the load. By setting the voltage threshold VT1 during the heavy load active mode during the period when the power is turned on, the image forming apparatus 1 can be started safely without opening the aluminum electrolytic capacitor 22. Note that the voltage threshold VT1 set when the power is turned on as shown in Figure 9 is then set to the voltage threshold VT corresponding to the operating mode through the processing in Figures 7 and 8.

Figure 10 is a block diagram showing an example of the hardware configuration of the controller 50 in Figure 2. For example, the controller 50 has a CPU 501, a ROM (Read Only Memory) 502, a RAM (Random Access Memory) 503, an external storage device 504, an input/output interface unit 505, and a communication interface unit 506, which are interconnected via a bus BUS.

The CPU 501 is an example of a computer that executes a power control program. The CPU 501 controls the overall operation of the image forming apparatus 1. For example, the CPU 501 executes a power control program stored in the ROM 502 or the external storage device 504 to implement a power control method that includes the functions of the threshold change unit 52 described above.

ROM 502 stores, for example, the control program and power supply control program of image forming apparatus 1. The control program of image forming apparatus 1 may include the power supply control program. RAM 503 is used, for example, as a work area for CPU 501, holds the control program and power supply control program of image forming apparatus 1 in an executable state, and stores various parameters.

The external storage device 504 is a hard disk drive (HDD) or a solid state drive (SSD), etc. For example, the external storage device 504 stores control programs such as an operating system (OS) that control the operation of the image forming device 1.

The input/output interface unit 505 transmits and receives information to and from the operation unit and display screen of the image forming apparatus 1. The input/output interface unit 505 also outputs the detected voltage value received from the voltage detection unit 24 to the CPU 501, and outputs a shutdown signal OFF to the power supply device 20 based on instructions from the CPU 501. For example, the communication interface unit 506 is connected to a network.

As described above, in this embodiment, the higher the expected valve-opening voltage in an operating mode, the higher the voltage threshold VT is set, thereby preventing the power supply from being unnecessarily shut off at a voltage that does not pose a risk of opening the valve of the aluminum electrolytic capacitor 22. As a result, unnecessary downtime can be reduced while preventing the valve of the electrolytic capacitor from opening, and unnecessary repair service costs can be reduced.

For each operating mode, the higher the ambient temperature of the aluminum electrolytic capacitor 22, the lower the voltage threshold VT, thereby appropriately preventing the aluminum electrolytic capacitor 22 from opening depending on the operating mode and ambient temperature. As a result, unnecessary downtime can be reduced, and unnecessary repair service costs can be avoided.

By setting the voltage threshold VT1 during the heavy load period when the power is turned on to the active mode voltage threshold VT1, the image forming device 1 can be started safely without opening the aluminum electrolytic capacitor 22.

Figure 11 is a block diagram showing an outline of another power supply device and a load to which a DC voltage is supplied from the other power supply device. Elements similar to those in Figure 2 are designated by the same reference numerals and detailed descriptions are omitted.

The image forming apparatus 1A shown in FIG. 11 has a power supply device 20A instead of the power supply device 20 in FIG. 4, and a load 40A instead of the load 40 in FIG. 4. The power supply device 20A has the same configuration and function as the power supply device 20 in FIG. 2, except that it does not have the temperature detection unit 25 in FIG. 2. The load 40A has the same configuration and function as the load 40 in FIG. 2, except that it has a controller 50A instead of the controller 50 in FIG. 2.

The controller 50A does not have the threshold change unit 52 and threshold table 54 of Figure 2. The controller 50A determines whether to output the shutoff signal OFF based on the fixed voltage threshold VT1, regardless of the operating mode (active mode, standby mode, or energy-saving mode) of the image forming apparatus 1A. The fixed voltage threshold VT1 is the voltage threshold VT1 shown in Figure 4.

For example, regardless of the operating mode, if the voltage detected by the voltage detection unit 24 is equal to or greater than the voltage threshold VT1, the controller 50A outputs a shutdown signal OFF, causing the power shutdown unit 26 to shut off the power. For example, as shown in FIG. 4, in energy-saving mode, the expected valve-opening voltage is higher than in active mode, and the valve-opening voltage has a sufficient margin above the voltage threshold VT1. However, since the image forming apparatus 1A has only one fixed voltage threshold VT1, even in energy-saving mode, if the voltage detected by the voltage detection unit 24 reaches the voltage threshold VT1, the power will be shut off. Because the power will be shut off at a voltage that would not normally require power shutdown, unnecessary downtime will occur, or unnecessary repair service costs will be incurred.

The present invention has been described above based on various embodiments, but the present invention is not limited to the requirements set forth in the above embodiments. These aspects can be modified without departing from the spirit of the present invention, and can be determined appropriately depending on the application form.

1, 1A Image forming apparatus 2 Automatic document feeder 3 Image reading device 4 Writing unit 5 Printer unit 6 Photosensitive drum 7 Developing device 8 Conveyor belt 9 Fixing device 10 Paper feed tray 10
20, 20A Power supply device 30 AC power supply 21 Diode bridge 22 Aluminum electrolytic capacitor 23 Converter section 24 Voltage detection section 25 Temperature detection section 26 Power supply cutoff section 27 Fuse 30 AC power supply 40, 40A Load 41 Charger 42 Motor 50, 50A Controller 52 Threshold value changing section 54 Threshold value table 501 CPU
502 ROM
503 RAM
504 External storage device 505 Input/output interface unit 506 Communication interface unit OFF Shutdown signal VT1 (VT11, VT12, VT13) Voltage threshold VT2 (VT21, VT22, VT23) Voltage threshold VT1 (VT31, VT32, VT33) Voltage threshold

Japanese Patent Application Laid-Open No. 2020-145828

Claims (6)

A power supply control device for controlling a power supply device having a rectifier unit including an electrolytic capacitor and converting an AC voltage into a DC voltage, a voltage generating unit that converts the DC voltage into a predetermined voltage to be supplied to a load device, and a power supply cutoff unit that cuts off the supply of the AC voltage to the rectifier unit in response to a cutoff signal,
a voltage detection unit that detects a voltage value of the DC voltage or the AC voltage;
a threshold value storage unit that stores a plurality of voltage threshold values corresponding to a plurality of operation modes of the load device;
a control unit that selects a voltage threshold corresponding to the operation mode in operation from among the plurality of voltage thresholds held in the threshold holding unit, and outputs the shutdown signal when the voltage value detected by the voltage detection unit is equal to or greater than the selected voltage threshold;
A power supply control device comprising: 2. The power supply control device according to claim 1, wherein the control unit selects a voltage threshold at the timing when the operation mode transition is determined if the value of the voltage threshold to be selected increases due to the transition of the operation mode, and selects a voltage threshold at the timing when the transition of the operation mode is determined if the value of the voltage threshold to be selected decreases due to the transition of the operation mode. a temperature detection unit for detecting an ambient temperature of the electrolytic capacitor;
the threshold value holding unit holds a plurality of voltage threshold values whose values change for each predetermined temperature in correspondence with each of the plurality of operation modes;
3. The power supply control device according to claim 1, wherein the control unit selects a voltage threshold value corresponding to the operating mode in operation and the ambient temperature detected by the temperature detection unit from among the plurality of voltage threshold values held in the threshold holding unit, and outputs the shutdown signal when the voltage value detected by the voltage detection unit is equal to or greater than the selected voltage threshold value. 4. The power supply control device according to claim 1, wherein the control unit selects the lowest voltage threshold from among the plurality of voltage thresholds held in the threshold holding unit when power is turned on to start supplying voltage to the load device. an image forming unit that forms an image;
a power supply device including a rectifier unit including an electrolytic capacitor for converting AC voltage into DC voltage, a voltage generating unit for converting the DC voltage into a predetermined voltage to be supplied to the image forming unit, and a power cutoff unit for cutting off the supply of AC voltage to the rectifier unit in response to a cutoff signal;
a voltage detection unit that detects a voltage value of the DC voltage or the AC voltage;
a threshold value storage unit that stores a plurality of voltage threshold values corresponding to a plurality of operation modes of the image forming unit;
a control unit that selects a voltage threshold corresponding to the operation mode in operation from among the plurality of voltage thresholds held in the threshold holding unit, and outputs the shutdown signal when the voltage value detected by the voltage detection unit is equal to or greater than the selected voltage threshold;
An image forming apparatus comprising: A power supply control method for controlling a power supply device having a rectifier unit including an electrolytic capacitor and converting an AC voltage into a DC voltage, a voltage generator unit that converts the DC voltage into a predetermined voltage to be supplied to a load device, and a power supply cutoff unit that cuts off the supply of the AC voltage to the rectifier unit in response to a cutoff signal,
Detecting a voltage value of the DC voltage or the AC voltage;
a threshold value storage unit that stores a plurality of voltage thresholds corresponding to a plurality of operation modes of the load device, and a voltage threshold value corresponding to the operation mode being operated is selected from among the plurality of voltage threshold values stored in the threshold value storage unit, and the shutdown signal is output when the detected voltage value is equal to or greater than the selected voltage threshold value.