Power supply control device, image forming apparatus and power supply control method

Abstract

To reduce frequency of occurrence of downtime and cost for repair services while suppressing valve-opening of an electrolytic capacitor installed on a power supply circuit.SOLUTION: A power supply control device for controlling a power supply device has: a rectification unit including an electrolytic capacitor, for converting an AC voltage to a 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 supply breaking unit for breaking supply of the AC voltage to the rectification unit in response to a breaking signal. The power supply control device is characterized by having: a voltage detection unit for detecting a voltage value of the DC voltage or the AC voltage; a threshold value holding unit for holding a plurality of voltage threshold values corresponding to respective operation modes of the load device; and a control unit that selects a voltage threshold value corresponding to one operation mode being operated among the plurality of operation modes held in the threshold value holding unit to output the breaking signal when a voltage value detected by the voltage detection unit is the selected voltage threshold value or more.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a power supply control device, an image forming apparatus, and a power supply control method. [Background technology]

[0002] In a power supply device, a technology is known in which a protection circuit is activated to cut off the current path when an overvoltage occurs in the input AC voltage, thereby preventing the valve of a smoothing electrolytic capacitor from opening due to the overvoltage (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0003] This type of technology activates the protection circuit when the effective AC voltage exceeds a threshold, regardless of the load state. When the threshold is set for the effective voltage without considering the load state, the threshold is set low to ensure safety and allow the protection circuit to operate with a margin of error. This can lead to the problem of the protection circuit operating even under conditions where there is no possibility of the electrolytic capacitor opening. This can result in unnecessary downtime or unnecessary repair service costs.

[0004] In view of the above problems, an object of the present invention is to reduce the frequency of downtime and the cost of repair services while preventing the valve of an electrolytic capacitor provided in a power supply circuit from opening. [Means for solving the problem]

[0005] 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 rectification unit that includes an electrolytic capacitor and converts AC voltage into DC voltage, a voltage generation unit that converts the DC voltage into a predetermined voltage to be supplied to a load device, and a power supply cut-off unit that cuts off the supply of AC voltage to the rectification unit in response to a cut-off signal, and 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 a plurality of voltage thresholds corresponding to a plurality of operating modes of the load device; and a control unit that selects a voltage threshold from the plurality of voltage thresholds held in the threshold holding unit 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. [Effects of the Invention]

[0006] It is possible to prevent the electrolytic capacitor provided in the power supply circuit from opening, while reducing the frequency of downtime and the cost of repair services. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating the overall configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] 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. [Figure 3] 3 is an explanatory diagram showing an example of specifications of voltage thresholds stored in the threshold table of FIG. 2. FIG. [Figure 4] 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. [Figure 5] 3 is a state transition diagram showing the transition of operation modes of the image forming apparatus of FIG. 2. FIG. [Figure 6] 3 is an explanatory diagram showing an example of the timing of transition of the operation mode of the image forming apparatus of FIG. 2 and change of the voltage threshold value. [Figure 7] 3 is a flow chart showing an example of control of a power cutoff unit by the controller of FIG. 2. [Figure 8]FIG. 8 is a flowchart showing an example of the process of step S200 in FIG. 7. [Figure 9] 4 is a flowchart showing an example of setting a voltage threshold value by a threshold value changing unit when the image forming apparatus in FIG. 2 is powered on; [Figure 10] 3 is a block diagram showing an example of a hardware configuration of a controller in FIG. 2. FIG. [Figure 11] 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. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the drawings. In the following, a symbol indicating a signal is also used to indicate a signal value or a signal line. A symbol indicating a voltage is also used to indicate a voltage value or a voltage line through which the voltage is supplied.

[0009] FIG. 1 is a diagram illustrating the overall configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 illustrated in FIG. 1 is, for example, a digital multifunction peripheral (MFP: Multi-Function Printer) having 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.

[0010] Furthermore, the internal state of the image forming apparatus 1 switches to an operating mode (operating state), a standby mode (standby state), an energy saving mode (low power state), etc. depending on the state of the internal circuit. Hereinafter, the energy saving mode is also referred to as an energy saving mode.

[0011] 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 an original document is scanned or a transmission / reception operation in facsimile mode. The state of the internal circuitry is switched by a user operating the operation unit or by control within the image forming apparatus 1.

[0012] For example, image forming apparatus 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 a paper medium or the like based on image information. Below, as an example of the flow of image formation in image forming apparatus 1, a brief description will be given of the case where the operating mode is set to copy mode.

[0013] In copy mode, multiple originals to be copied are set in automatic document feeder 2. When a start button on an operation unit (not shown) is pressed, automatic document feeder 2 feeds the originals one by one to image reading device 3. Image reading device 3 reads the image information of each original sent in order from automatic document feeder 2. The image information read by image reading device 3 is processed by an image processing unit (not shown).

[0014] 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 image of the original has been copied is then discharged from the discharge section.

[0015] 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 apparatus 1 returns to the standby mode, and if the standby mode continues for a predetermined time, it enters the energy saving mode. Then, if the operation unit is operated during the energy saving mode, the image forming apparatus 1 returns to the standby mode.

[0016] The power supply device 20 converts AC voltage supplied from an AC power supply 30 such as a commercial power supply into DC voltage, and supplies the converted DC voltage to various loads such as the printer unit 5 of the image forming apparatus 1. For example, the loads include various motors, a charger that charges the photosensitive drum 6, and a developing roller of the developing device 7. The image forming apparatus 1 may have multiple power supply devices 20 corresponding to the chargers and developing rollers, respectively.

[0017] 2 is a block diagram showing an outline of power supply device 20 in FIG. 1 and a load to which a DC voltage is supplied from power supply device 20. 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 cutoff unit 26, and a fuse 27.

[0018] 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 smoothes the full-wave rectified voltage to generate a DC voltage. The diode bridge 21 and the aluminum electrolytic capacitor 22 are an example of a rectifier unit. Note that the power supply device 20 may include an electrolytic capacitor other than the aluminum electrolytic capacitor 22.

[0019] Converter unit 23 generates a DC voltage such as 5 V or 24 V corresponding to the operating voltage of load 40 from the smoothed DC voltage, and supplies the generated DC voltage to load 40. Note that the value of the DC voltage generated by converter unit 23 may be other than 5 V or 24 V. Converter unit 23 is an example of a voltage generation unit.

[0020] For example, the load 40 includes a 24V load and a 5V load. The 24V load includes a 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, etc. The 12V load includes a controller 50 that controls the overall operation of the image forming apparatus 1, etc. 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.

[0021] The controller 50, for example, executes a program to control the entire image forming apparatus 1. The controller 50 has a threshold value changing unit 52 and a threshold value table 54. For example, the threshold value table 54 is stored in an internal memory of the controller 50, but may also be stored in an external memory connected to the outside of the controller 50.

[0022] The controller 50 may be in the form of a motherboard or a CPU (Central Processing Unit) that executes a program such as a power supply control program. Furthermore, the controller 50 may be in the form of an SoC (System on a Chip) that includes a CPU that executes a program such as a power supply control program, or in the form of an ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array).

[0023] 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 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 in the controller 50.

[0024] The DC voltage applied to the aluminum electrolytic capacitor 22 changes depending on the voltage fluctuation of 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.

[0025] 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 proximity to the aluminum electrolytic capacitor 22. The temperature detection unit 25 may 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 in the controller 50. Furthermore, if the voltage threshold VT is not changed in accordance with the temperature by the threshold change unit 52 (described later), the temperature detection unit 25 may not be provided.

[0026] 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 of the voltage 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 cutoff of the power supply.

[0027] Commercial power supplied from external power supply equipment may output abnormal overvoltage depending on the performance, reliability, or installation environment of the power supply equipment. If an abnormal overvoltage exceeding the withstand voltage specification is applied to aluminum electrolytic capacitor 22, there is a risk that aluminum electrolytic capacitor 22 will open. In this embodiment, the shutoff operation of power supply shutoff unit 26 can prevent an abnormal overvoltage exceeding the withstand voltage specification from being applied to aluminum electrolytic capacitor 22, thereby preventing aluminum electrolytic capacitor 22 from opening.

[0028] 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.

[0029] 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 shutoff signal OFF, causing the power cutoff unit 26 to cut off the power. The voltage threshold VT is a voltage value that triggers the controller 50 to output the shutoff signal OFF. The threshold change unit 52 changes the voltage threshold VT according to the operation mode of the image forming apparatus 1. That is, the controller 50 selects a voltage threshold VT corresponding to the current operation mode from a threshold table 54, and outputs the shutoff 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 operation mode. The threshold table 54 is an example of a threshold holding unit.

[0030] If the temperature detection unit 25 is provided, the threshold value table 54 may hold a plurality of voltage threshold values ​​corresponding to predetermined temperature ranges, respectively, for a plurality of operation modes. In this case, the controller 50 outputs the shutdown signal OFF when the voltage value detected by the voltage detection unit 24 is equal to or greater than the voltage threshold value VT for each operation mode held in the threshold value table 54 in correspondence with the current temperature. If the temperature detection unit 25 is not provided, the controller 50 outputs the shutdown signal OFF when the voltage value detected by the voltage detection unit 24 is equal to or greater than the voltage threshold value VT held in the threshold value table 54 in correspondence with the operation mode.

[0031] 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 device whose load varies depending on the operation.

[0032] Fig. 3 is an explanatory diagram showing an example of the specifications of the voltage thresholds VT stored in the threshold table 54 of Fig. 2. For example, three voltage thresholds VT (VT1, VT2, VT3) corresponding to three operation modes are stored in the threshold table 54. The magnitude relationship among the three voltage thresholds VT is VT3>VT2>VT1.

[0033] The voltage threshold VT1 is used by the controller 50 to determine whether an overvoltage has occurred during the active mode (during the copy mode or the print mode). The voltage threshold VT2 is used by the controller 50 to determine whether an overvoltage has occurred during the standby mode. The voltage threshold VT1 is used by the controller 50 to determine whether an overvoltage has occurred during the energy saving mode.

[0034] The voltage threshold value VT1 may be used by the controller 50 to determine whether an overvoltage has occurred during a scanning operation in the scanner mode or during a transmission / reception operation in the facsimile mode. In this case, the scanner mode and the facsimile mode are also included in the active mode.

[0035] The active mode, standby mode, and energy saving mode have 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 smaller than the load of a copying mode or a printing mode, but larger than the load of a standby mode. For this reason, 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.

[0036] Fig. 4 is an explanatory diagram showing an example of the relationship between the voltage threshold value and the valve-opening voltage VT in each operation mode in Fig. 3. The voltage threshold value VT1 is set to a value that is lower by a predetermined margin value than the design value (estimated value) of the valve-opening voltage in active mode.

[0037] The voltage threshold VT2 is set to a value lower by a predetermined margin than the design value (estimated value) of the valve-opening voltage in standby mode and 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 lower by a predetermined margin than the design value (estimated value) of the valve-opening voltage in energy-saving mode and higher than the design value (estimated value) of the valve-opening voltage in standby mode.

[0038] For example, in energy-saving mode, the controller 50 does not output a shutoff signal OFF when the voltage detection unit 24 detects a voltage lower than the voltage threshold VT3, but outputs the shutoff signal OFF when it detects a voltage equal to or higher than the voltage threshold VT3. In contrast, for example, assume that the power supply is shut off at a voltage equal to or higher than the voltage threshold VT1 corresponding to the minimum expected value of the valve-opening voltage, regardless of the operating mode. In this case, in energy-saving mode, the power supply is shut off when a voltage between the voltage threshold VT1 and the voltage threshold VT3, which does not normally require shutoff of the power supply, is detected. Similarly, in standby mode, the power supply is shut off when a voltage between the voltage threshold VT1 and the voltage threshold VT2, which does not normally require shutoff of the power supply, is detected.

[0039] In this embodiment, by setting a higher voltage threshold value VT for an operation mode with a higher expected valve-opening voltage, it is possible to prevent unnecessary power cut-off at a voltage that does not risk opening the valve of aluminum electrolytic capacitor 22. As a result, it is possible to prevent unnecessary downtime from occurring, or to prevent unnecessary repair service costs from occurring.

[0040] The voltage thresholds VT (VT11-VT13, VT21-VT23, VT31-VT33) shown in parentheses are examples of voltage thresholds VT held 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). In this way, when the temperature detection unit 25 is provided, the threshold change unit 52 selects one of the 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.

[0041] 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.

[0042] When an overvoltage is applied, the aluminum electrolytic capacitor 22 generates heat and opens its valve, so the higher the ambient temperature (the temperature of the case of the aluminum electrolytic capacitor 22), the more likely the valve is to open. Therefore, when the ambient temperature is high, lowering the voltage threshold VT (changing it to the safe side) can appropriately prevent 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 reduced.

[0043] 5 is a state transition diagram showing transitions between operation modes of the image forming apparatus 1 of FIG. 2. When the image forming apparatus 1 detects transition trigger information indicating a transition to standby mode during the energy saving mode, the image forming apparatus 1 transitions to standby mode, and when the image forming apparatus 1 detects transition trigger information indicating a transition to active mode, the image forming apparatus 1 transitions to active mode. In the energy saving mode, the controller 50 controls the power cutoff unit 26 using the voltage threshold value VT3. When the temperature detection unit 25 is provided, the voltage threshold values ​​VT31-VT33 are used.

[0044] When the image forming apparatus 1 detects transition trigger information indicating a transition to the energy saving mode during standby mode, the image forming apparatus 1 transitions to the energy saving mode, and when the image forming apparatus 1 detects transition trigger information indicating a transition to the active mode, the image forming apparatus 1 transitions to the active mode. In standby mode, the controller 50 controls the power cutoff unit 26 using the voltage threshold value VT2. When the temperature detection unit 25 is provided, the voltage threshold values ​​VT21-VT23 are used.

[0045] When the image forming apparatus 1 detects transition trigger information indicating a transition to the energy saving mode during the active mode, the image forming apparatus 1 transitions to the energy saving mode, and when the image forming apparatus 1 detects transition trigger information indicating a transition to the standby mode, the image forming apparatus 1 transitions to the standby mode. In the active mode, the controller 50 controls the power cutoff unit 26 using the voltage threshold value VT1. When the temperature detection unit 25 is provided, the voltage threshold values ​​VT11-VT13 are used.

[0046] Fig. 6 is an explanatory diagram showing an example of the timing of the transition of the operating mode of the image forming apparatus 1 shown in Fig. 2 and the change of the voltage threshold value VT. Note that Figs. 6 to 8 show an example in which the temperature detection unit 25 is not provided. In the case where the temperature detection unit 25 is provided, the voltage threshold values ​​VT1, VT2, and VT3 become the voltage threshold values ​​VT11-VT13, VT21-VT23, and VT31-VT33 shown in Fig. 4 according to the temperature detected by the temperature detection unit 25.

[0047] As explained in Figure 4, the voltage thresholds VT1, VT2, and VT3 are set to values ​​that are lower by a predetermined margin than the expected valve-opening voltage value 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.

[0048] Therefore, when the value of the voltage threshold VT to be selected increases due to a transition of the operating mode, the threshold change unit 52 selects the voltage threshold VT at the timing of the transition of the operating mode, and sets this as the voltage threshold VT for determining whether to output the shutdown signal OFF. Also, when the value of the voltage threshold VT to be selected decreases due to a transition of the operating mode, the threshold change unit 52 selects the voltage threshold VT at the timing when the transition of the operating mode is determined by the transition trigger information, and sets this as the voltage threshold VT for determining whether to output the shutdown signal OFF.

[0049] For example, when transitioning from active mode to standby mode, the threshold change unit 52 detects transition trigger information and then changes the voltage threshold from VT1 to VT2 at the timing when the operation mode transitions to standby mode (FIG. 6(a)). When transitioning from standby mode to energy saving mode, the threshold change unit 52 detects transition trigger information and then changes the voltage threshold from VT2 to VT3 at the timing when the operation mode transitions to energy saving mode (FIG. 6(b)).

[0050] When transitioning from energy saving mode to active mode, threshold changing unit 52 changes the voltage threshold from VT3 to VT1 based on the detection of transition trigger information (FIG. 6(c)). When transitioning from active mode to energy saving mode, threshold changing unit 52 changes the voltage threshold from VT1 to VT3 at the timing when the operation mode transitions to energy saving mode after detecting the transition trigger information (FIG. 6(d)).

[0051] When the power saving mode is shifted to the standby mode, the threshold change unit 52 changes the voltage threshold from VT3 to VT2 based on the detection of the shift trigger information (FIG. 6(e)). When the power saving mode is shifted to the active mode, the threshold change unit 52 changes the voltage threshold from VT2 to VT1 based on the detection of the shift trigger information (FIG. 6(f)).

[0052] Fig. 7 is a flow diagram showing an example of control of power cut-off unit 26 by controller 50 of Fig. 2. The operation shown in Fig. 7 may be realized by the hardware of controller 50, may be realized by a CPU mounted on controller 50 executing a power control program, or may be realized by a combination of hardware and software. For example, the operation shown in Fig. 7 is started after the process shown in Fig. 9, which will be described later, is executed when the power of image forming apparatus 1 is turned on.

[0053] 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 the transition trigger information, it proceeds to step S104, and if the controller 50 does not detect the transition trigger information, it executes step S102 again. For example, the transition trigger information is generated within the image forming apparatus 1 by an instruction to start copying, receipt of a print job, completion of a print job, cancellation of the energy saving mode, etc.

[0054] For example, the energy saving mode is cancelled when a touch panel provided on the image forming apparatus 1 is operated, or when the automatic document feeder 2 is lifted up to expose the platen glass for image scanning. The transition to the standby mode is made after printing on paper media is completed.

[0055] In step S104, the controller 50 determines whether the transition trigger information indicates a transition to the active mode. If the transition trigger information indicates a transition to the active mode, the controller 50 transitions the process to step S110. If the transition trigger information does not indicate a transition to the active mode, the controller 50 transitions the process to step S106.

[0056] 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 the process 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 the process to step S114.

[0057] In step S110, the controller 50 refers to 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 refers to 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.

[0058] In step S114, controller 50 refers to threshold value table 54, determines the threshold voltage to be changed to voltage threshold value VT3 corresponding to the energy saving mode, and proceeds to step S200. Note that controller 50 determines the voltage threshold to be changed in steps S110, S112, and S114, but changes the determined voltage threshold value by the processing in step S200.

[0059] In step S200, the controller 50 performs a process of changing the voltage threshold value, and then ends the process shown in Fig. 7. After that, the controller 50 controls the power cut-off unit 26 by controlling the generation of the cut-off signal OFF using the voltage threshold value according to the operation mode.

[0060] Fig. 8 is a flow diagram showing an example of the process of step S200 in Fig. 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 shifts the process to step S208. If the current voltage threshold is not VT1, the controller 50 shifts the process to step S204.

[0061] 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.

[0062] 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.

[0063] In step S208, after the transition of the operation 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 operation mode, the controller 50 sets the voltage threshold to VT1 or VT2, and ends the processing shown in Fig. 8. This makes it possible to realize the operation of changing the voltage threshold VT shown in Fig. 6.

[0064] Fig. 9 is a flow diagram showing an example of setting the voltage threshold value by threshold value changing unit 52 when powering on image forming apparatus 1 in Fig. 2. The operation shown in Fig. 9 is started when power to image forming apparatus 1 is turned on and converter unit 23 starts generating a 5V DC voltage.

[0065] 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, the process proceeds to step S304. If the controller 50 does not detect trigger information indicating power-on, the controller 50 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.

[0066] 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 the temperature detection unit 25 is provided, the controller 50 may set the voltage threshold VT11 in Fig. 4 in step S304.

[0067] 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 value 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 value VT1 set when the power is turned on as shown in FIG. 9 is then set to the voltage threshold value VT according to the operating mode through the processes shown in FIGS. 7 and 8.

[0068] Fig. 10 is a block diagram showing an example of the hardware configuration of the controller 50 in Fig. 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 by a bus BUS.

[0069] 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 including the function of the threshold value changing unit 52 described above.

[0070] The ROM 502 stores, for example, a control program and a power supply control program for the image forming apparatus 1. The control program for the image forming apparatus 1 may include the power supply control program. The RAM 503 is used, for example, as a work area for the CPU 501, holds the control program and the power supply control program for the image forming apparatus 1 in an executable manner, and stores various parameters.

[0071] 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 controls the operation of the image forming apparatus 1.

[0072] The input / output interface unit 505 transmits and receives information to and from the operation unit, display screen, etc. 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 shutoff signal OFF to the power supply device 20 based on an instruction from the CPU 501. For example, the communication interface unit 506 is connected to a network.

[0073] As described above, in this embodiment, by setting a higher voltage threshold value VT for an operation mode with a higher expected valve-opening voltage, it is possible to prevent unnecessary power cut-off at a voltage that does not risk opening the valve of aluminum electrolytic capacitor 22. As a result, it is possible to prevent unnecessary downtime from occurring while preventing the valve of the electrolytic capacitor from opening, or to prevent unnecessary repair service costs from occurring.

[0074] 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 valve of the aluminum electrolytic capacitor 22 from opening according to the operating mode and the ambient temperature. As a result, unnecessary downtime can be prevented, and unnecessary repair service costs can be reduced.

[0075] By setting the voltage threshold value VT1 for the active mode when the load is heavy during the period when the power is turned on, the image forming apparatus 1 can be started safely without opening the valve of the aluminum electrolytic capacitor 22.

[0076] 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 FIG. 2 are given the same reference numerals and detailed description thereof will be omitted.

[0077] Image forming apparatus 1A shown in FIG. 11 has a power supply device 20A instead of power supply device 20 in FIG. 4, and a load 40A instead of load 40 in FIG. 4. Power supply device 20A has the same configuration and function as power supply device 20 in FIG. 2, except that it does not have temperature detection unit 25 in FIG. 2. Load 40A has the same configuration and function as load 40 in FIG. 2, except that it has a controller 50A instead of controller 50 in FIG. 2.

[0078] Controller 50A does not have threshold value changing unit 52 and threshold value table 54 shown in Fig. 2. Controller 50A determines whether to output a shutoff signal OFF based on a fixed voltage threshold value VT1, regardless of the operating mode (active mode, standby mode, or energy-saving mode) of image forming apparatus 1A. Fixed voltage threshold value VT1 is the voltage threshold value VT1 shown in Fig. 4.

[0079] For example, regardless of the operating mode, when the voltage detected by the voltage detection unit 24 is equal to or greater than the voltage threshold VT1, the controller 50A outputs a shutoff signal OFF to cause the power cutoff unit 26 to cut off the power. For example, as shown in FIG. 4, in energy-saving mode, the expected value of the 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 is cut off. Because the power is cut off at a voltage that would not normally require power cutoff, unnecessary downtime occurs, or unnecessary repair service costs are incurred.

[0080] Although the present invention has been described above based on the embodiments, the present invention is not limited to the requirements shown in the above embodiments. These requirements can be changed without departing from the spirit of the present invention, and can be appropriately determined depending on the application form. [Explanation of symbols]

[0081] 1, 1A Image forming device 2 Automatic document feeder 3. Image reading device 4 Write Unit 5 Printer unit 6 Photosensitive drum 7. Developing device 8 conveyor belt 9 Fixing device 10 Paper Tray 10 20, 20A power supply 30 AC power supply 21 Diode Bridge 22 Aluminum electrolytic capacitors 23 Converter section 24 Voltage detection section 25 Temperature detection unit 26 Power cutoff section 27. Fuse 30 AC power supply 40, 40A load 41 Charger 42 Motor 50, 50A controller 52 Threshold change unit 54 Threshold Table 501 CPU 502 ROM 503 RAM 504 External storage device 505 Input / Output Interface Section 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 [Prior art documents] [Patent documents]

[0082] [Patent Document 1] Japanese Patent Application Publication No. 2020-145828

Claims

1. 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. When the transition of the operation mode causes a voltage threshold value to be selected to increase, the control unit selects the voltage threshold value at the timing when the transition of the operation mode occurs, and when the transition of the operation mode causes a voltage threshold value to be selected to decrease, the control unit selects the voltage threshold value at the timing when the transition of the operation mode is determined. The power supply control device according to claim 1 ,

3. 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; The control unit selects a voltage threshold value corresponding to the operation mode during operation and the ambient temperature detected by the temperature detection unit from among the plurality of voltage threshold values ​​held in the threshold value holding unit, and outputs the cutoff signal when the voltage value detected by the voltage detection unit is equal to or greater than the selected voltage threshold value.

3. The power supply control device according to claim 1 or 2, wherein:

4. The control unit selects the lowest voltage threshold value from among the plurality of voltage threshold values ​​held in the threshold value holding unit when power is turned on to start supplying voltage to the load device.

4. The power supply control device according to claim 1, wherein:

5. 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 generator 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:

6. 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 threshold values ​​corresponding to the plurality of operation modes of the load device, and a voltage threshold value corresponding to the operation mode being operated is selected from 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; A power supply control method comprising:

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