Image formation device and control method of image formation device

Abstract

To sense overvoltage of AC power supply while suppressing power consumption.SOLUTION: An image formation device comprises: an image formation part that forms an image on the basis of an AC voltage inputted from the outside; a voltage sensing part that senses a value of the AC voltage; a switching part that switches a path through which the AC voltage is distributed to the voltage sensing part, into a conduction state or a cut-off state; a functioning part which produces heat in accordance with the AC voltage or makes currents flow therethrough; a state sensing part that senses a temperature or currents of the functioning part; and a control part that estimates a value of the AC voltage on the basis of the temperature or the currents sensed by the state sensing part, and switches the switching part in the cut-off state into the conduction state, when the estimated value of the AC voltage shows a sign of overvoltage.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus and a control method for an image forming apparatus. [Background technology]

[0002] In a power supply device, there is known a technique for displaying a warning message on a display panel when an overvoltage is input from an AC power supply, or for cutting off the AC power input by blowing a fuse or controlling a relay (see, for example, Patent Document 1). There is also known a technique for providing an auxiliary power supply with a smaller power capacity than a switching power supply, detecting the charging voltage of a capacitor on the auxiliary power supply side, and determining the magnitude of the AC voltage based on the detected charging voltage (see, for example, Patent Document 2). Summary of the Invention [Problem to be solved by the invention]

[0003] However, no method has been proposed for reducing power consumption by not operating a voltage detection unit that detects overvoltage in AC voltage all the time, but by operating the voltage detection unit only when signs of overvoltage in AC voltage are detected.

[0004] In view of the above-mentioned problems, an object of the present invention is to detect an overvoltage of an AC power supply while suppressing power consumption. [Means for solving the problem]

[0005] In order to solve the above technical problems, an image forming apparatus of one embodiment of the present invention is characterized by having an image forming unit that forms an image based on an AC voltage input from outside, a voltage detection unit that detects the value of the AC voltage, a switching unit that switches the current path of the AC voltage to the voltage detection unit between a conductive state and a cut-off state, a functional unit that generates heat or flows current in accordance with the AC voltage, a state detection unit that detects the temperature or current of the functional unit, and a control unit that estimates the value of the AC voltage based on the temperature or current detected by the state detection unit, and switches the switching unit, which is in a cut-off state, to a conductive state if the estimated value of the AC voltage shows signs of overvoltage. [Effects of the Invention]

[0006] It is possible to detect an overvoltage of an AC power supply while suppressing power consumption. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective cross-sectional view showing an example of the overall configuration of an image forming apparatus according to a first embodiment of the present invention. [Figure 2] 2 is a block diagram showing an example of a main part of the image forming apparatus shown in FIG. 1. FIG. [Figure 3] FIG. 10 is a diagram showing an example of the relationship between an AC voltage value Va that turns on a switching unit in an energy saving mode, an AC voltage value Vb that displays a warning message on the operation panel of FIG. 2, and an AC voltage value Vc that cuts off the power supply cutoff unit of FIG. 2. [Figure 4] FIG. 10 is a diagram illustrating an example of a warning message displayed on an operation panel. [Figure 5] 3 is a flowchart showing an example of an operation for protecting the power supply device of FIG. 2 from an overvoltage. [Figure 6] FIG. 10 is a block diagram showing an example of a main part of an image forming apparatus according to a second embodiment of the present invention. [Figure 7] 7 is a flowchart showing an example of an operation for protecting the power supply device of FIG. 6 from an overvoltage. [Figure 8] 7 is a flowchart showing another example of the operation of protecting the power supply device of FIG. 6 from an overvoltage. [Figure 9] FIG. 10 is a block diagram showing an example of a main part of an image forming apparatus according to a third embodiment of the present invention. [Figure 10] 10 is a flowchart showing an example of an operation for protecting the power supply device of FIG. 9 from an overvoltage. [Figure 11] FIG. 10 is a block diagram showing an example of a main part of an image forming apparatus according to a fourth embodiment of the present invention. [Figure 12] 12 is a flowchart showing an example of an operation for protecting the power supply device of FIG. 11 from an overvoltage. [Figure 13] FIG. 3 is a block diagram showing an example of a hardware configuration of a controller shown in FIGS. 1 and 2. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and duplicated explanations may be omitted. In the following, the voltage lines through which voltages are transmitted will be designated by the same reference numerals as the voltage names.

[0009] (First embodiment) Fig. 1 is a perspective cross-sectional view showing an example of the overall configuration of an image forming apparatus according to a first embodiment of the present invention. The image forming apparatus 1 shown in Fig. 1 is, for example, a digital multifunction peripheral (MFP: Multi-Function Printer) having a facsimile function and one or more of a copy function, a print function, a scanner function, etc.

[0010] For example, the image forming apparatus 1 has an automatic document feeder (ADF) 2, an image reading device 3, a writing unit 4, a printer unit 5, an operation unit 11, a controller 12, and a power supply device 20. The 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 storing a paper feed tray 10.

[0011] The image forming apparatus 1 can be switched between copy function, printer function, and facsimile function in sequence using an application switching key on the operation unit 11 of the image forming apparatus 1. When the copy function is selected, the image forming apparatus 1 enters copy mode, when the printer function is selected, the image forming apparatus 1 enters printer mode, and when the facsimile mode is selected, the image forming apparatus 1 enters facsimile mode.

[0012] Furthermore, the image forming apparatus 1 switches its internal state between a normal mode, an energy-saving mode, etc., depending on the state of its internal circuitry. For example, the normal mode has an operating mode (operating state) in which the facsimile function, copy function, print function, or scanner function is realized, and a standby mode (standby state).

[0013] The standby mode is a mode in which the power supply device 20 generates various voltages and supplies them to each functional unit, so that each functional unit can immediately operate based on an operation instruction. The energy saving mode is a mode in which the supply of power from the power supply device 20 is stopped except for functional units that operate in the energy saving mode, and for example, image formation operations by the printer unit 5 are stopped. The transition from the energy saving mode to the standby mode or the operation mode, and the transition from the standby mode to the operation mode, are switched by the user of the image forming device 1 operating the operation unit 11 or by control within the image forming device 1 (for example, receiving a facsimile).

[0014] The power supply device 20 is connected to a commercial alternating current (AC) power supply via a power cable. The power supply device 20 uses AC voltage supplied from the commercial AC power supply to generate various DC voltages used by the automatic document feeder 2, image reading device 3, writing unit 4, printer unit 5, operation unit 11, etc. The power supply device 20 has a first power supply system that supplies power in normal mode and stops supplying power in energy saving mode and when the image forming apparatus 1 is powered off, and a second power supply system that supplies power in normal operation, energy saving mode, and when the image forming apparatus 1 is powered off.

[0015] The printer unit 5 forms an image by creating a toner image to be transferred to a paper medium or the like based on image information from an original or facsimile data. The printer unit 5 is an example of an image forming section that forms an image. Below, as an example of the flow of image formation in the image forming apparatus 1, a brief description will be given of the case where the operating mode is set to copy mode.

[0016] In the copy mode, a stack of documents (multiple documents) to be copied is set in the automatic document feeder 2, or the documents to be copied are set on the image reading device 3. When the start button displayed on the operation unit 11 is pressed, the automatic document feeder 2 feeds the documents one by one to the image reading device 3. The image reading device 3 reads the image information of each of the documents sent in order from the automatic document feeder 2 or the document set on the image reading device 3.

[0017] The writing unit 4 converts the image information read by the image reading device 3 into optical information. The photosensitive drum 6 is uniformly charged by a charger (not shown) positioned opposite the photosensitive drum 6, 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 to form a toner image on the photosensitive drum 6. The toner image formed on the photosensitive drum 6 is transferred to a paper medium or the like by a conveyor belt 8. A fixing device 9 fixes the toner image to the paper medium or the like. The paper medium on which the image of the original document has been copied is then discharged from the discharge section. The operation unit 11 accepts various inputs according to user operations and displays various information on the display unit of the operation unit 11.

[0018] The controller 12 may be a CPU (Central Processing Unit) or the like mounted on a control board (not shown), and controls the overall operation of the image forming apparatus 1. The controller 12 operates by receiving power from a battery (e.g., a secondary battery) (not shown) even when the image forming apparatus 1 is in an energy saving mode. The controller 12 operates constantly by receiving power from a second power supply system. The controller 12 is an example of a control unit.

[0019] 1 shows an example in which the image forming apparatus 1 is a digital multifunction peripheral. However, the image forming apparatus 1 may be an image forming apparatus having a single function such as a scanner, printer, or facsimile.

[0020] Fig. 2 is a block diagram showing an example of the main parts of the image forming apparatus 1 shown in Fig. 1. The power supply device 20 is connected to a commercial AC power source AC via a power cable, and has a function of supplying power to the load 13 using the AC voltage supplied from the commercial AC power source AC. For example, the power supply device 20 may be a switching power supply that smooths the AC voltage ACIN received from the AC power source AC and further converts the voltage to generate a DC voltage to be supplied to the load 13.

[0021] For example, the load 13 is the automatic document feeder 2, the image reading device 3, the writing unit 4, the printer unit 5, the operation unit 11, and the controller 12 shown in Fig. 1. The power supply device 20 is not limited to the image forming device 1 shown in Fig. 1, and may be installed in electronic devices such as a projector, an electronic whiteboard, a digital signage, an imaging device, a PC (Personal Computer), and a server.

[0022] The power supply device 20 includes a fuse 21, a power cutoff unit 22, a rectifier circuit 23, an electrolytic capacitor 24, a DC / DC converter 25 (DC stands for Direct Current), a switching unit 26, a voltage detection unit 27, and a state detection unit .

[0023] Fuse 21 is disposed between an input terminal that receives voltage input line ACIN and power cutoff unit 22, and protects power supply device 20 from overcurrent by cutting off (melting) when a fusing current determined by the fuse's electrical specifications flows. Power cutoff unit 22 is disposed between fuse 21 and rectifier circuit 23, and cuts off the supply of AC voltage ACIN to rectifier circuit 23 in response to a control signal from voltage detection unit 27. Power cutoff unit 22 operates by receiving power from the battery even during energy saving mode.

[0024] The rectifier circuit 23 is, for example, a full-wave rectifier circuit including a diode bridge, and rectifies the AC voltage ACIN and outputs it as a DC voltage (pulsating current) to the voltage line V1. The electrolytic capacitor 24 stores the voltage (pulsating current) output from the rectifier circuit 23 to smooth it, and generates a DC voltage V1 that depends on the amplitude of the AC voltage ACIN on the voltage line V1. The electrolytic capacitor 24 stores the DC voltage V1 obtained by rectifying the AC voltage ACIN received during the normal mode and the energy-saving mode. The DC / DC converter 25 generates one or more DC voltages to be supplied to the load 13 based on the DC voltage V1.

[0025] Switching unit 26 is disposed between power cutoff unit 22 and voltage detection unit 27. Switching unit 26 is set to a conductive state (ON) by a control signal received from controller 12 when image forming apparatus 1 is in the normal mode, and supplies AC voltage ACIN to voltage detection unit 27. As described in FIG. 1, the normal mode is an operation mode or standby mode in which the facsimile function, copy function, print function, or scanner function is realized.

[0026] Furthermore, switching unit 26 is set to a cutoff state (off) by a control signal received from controller 12 while image forming apparatus 1 is in the energy saving mode, and stops the supply of AC voltage ACIN to voltage detection unit 27. However, when switching unit 26 receives a control signal from controller 12 during the energy saving mode, it turns on and supplies AC voltage ACIN to voltage detection unit 27.

[0027] The voltage detection unit 27 operates by the AC voltage ACIN received while the switching unit 26 is on (for example, in normal mode), and detects whether the AC voltage ACIN is an overvoltage. The voltage detection unit 27 notifies the controller 12 of the detection result of the AC voltage ACIN (whether it is an overvoltage or not). If the notification from the voltage detection unit 27 indicates that the AC voltage ACIN is an overvoltage, the controller 12 displays a warning message on the operation panel 11a of the operation unit 11. This makes it possible to notify the user of the image forming apparatus 1 of the occurrence of an overvoltage. The operation panel 11a is an example of a display unit.

[0028] When voltage detection unit 27 detects an overvoltage of AC voltage ACIN, it outputs a control signal to power supply cutoff unit 22 to cut off power supply cutoff unit 22. By cutting off power supply cutoff unit 22 when an overvoltage occurs, it is possible to prevent the supply of an overvoltage to the inside of power supply device 20 and to protect power supply device 20 from the overvoltage.

[0029] While the switching unit 26 is off during the energy-saving mode, the voltage detection unit 27 does not receive the AC voltage ACIN and therefore stops operating. This allows for reduced power consumption during the energy-saving mode compared to other power supply devices that perform detection of the AC voltage ACIN even during the energy-saving mode. Note that an overvoltage state of the AC voltage ACIN may occur even during the energy-saving mode.

[0030] Therefore, when switching unit 26 is turned on under the control of controller 12 during the energy saving mode, voltage detection unit 27 receives AC voltage ACIN and operates to detect the value of AC voltage ACIN. When voltage detection unit 27 detects an overvoltage of AC voltage ACIN, it outputs a control signal to power supply cutoff unit 22 to cut off power supply cutoff unit 22. In this way, voltage detection unit 27 operates only when there is a possibility that protection of power supply device 20 is required during the energy saving mode.

[0031] The state detection unit 28 detects the temperature of the functional unit that generates heat in response to the AC voltage ACIN, or detects the value of the current flowing through the functional unit in response to the AC voltage ACIN. The state detection unit 28 notifies the controller 12 of information indicating the detected temperature or current value of the functional unit. For example, the functional unit is a heat-generating component or a component that consumes current that is mounted in the image forming apparatus 1 (including the power supply device 20) and is energized even in the energy-saving mode. The temperature of the functional unit may be not only the temperature of the functional unit itself, but also the temperature around the functional unit. The current of the functional unit is the current flowing through the functional unit (i.e., the consumed current).

[0032] The controller 12 includes a voltage estimation unit 12a that operates during the energy saving mode. The voltage estimation unit 12a estimates the value of the AC voltage ACIN based on temperature information or current information of the functional units notified by the state detection unit 28. If the value of the AC voltage ACIN estimated by the voltage estimation unit 12a during the energy saving mode indicates a sign of overvoltage, the controller 12 outputs a control signal to the switching unit 26, switching the switching unit 26 from its off state to its on state.

[0033] This allows voltage detection unit 27, which is stopped during the energy saving mode, to operate when the value of AC voltage ACIN indicates an overvoltage. Therefore, AC voltage ACIN can be constantly monitored directly or indirectly while minimizing power consumption during the energy saving mode, and if an overvoltage occurs, the supply of AC voltage ACIN can be cut off to protect the components of power supply device 20 from damage.

[0034] An overview of the operations of the switching unit 26, voltage detection unit 27, and voltage estimation unit 12a is shown in the table at the bottom of Fig. 2. In normal mode, the switching unit 26 is turned on. If the voltage detection unit 27 detects an overvoltage, a warning message is displayed on the operation panel 11a, and the power cut-off unit 22 cuts off the power.

[0035] In the energy-saving mode, the switching unit 26 is turned off. When the voltage estimation unit 12a predicts and detects signs of overvoltage, the switching unit 26 is turned on. After that, as in the normal mode, when the voltage detection unit 27 detects overvoltage, a warning message is displayed on the operation panel 11a, and the power cutoff unit 22 cuts off the power.

[0036] FIG. 3 is a diagram showing an example of the relationship between the value Va of the AC voltage ACIN that causes the switching unit 26 to be turned on in the energy-saving mode, the value Vb of the AC voltage ACIN that causes a warning message to be displayed on the operation panel 11a in FIG. 2, and the value Vc of the AC voltage ACIN that causes the power cutoff unit 22 in FIG. 2 to be cut off. Hereinafter, the values Va, Vb, and Vc of the AC voltage ACIN are also referred to as AC voltages Va, Vb, and Vc. Note that the AC voltage Va at which the switching unit 26 is turned on in the energy-saving mode is an estimated value by the voltage estimation unit 12a.

[0037] It is desirable that the AC voltages Va, Vb, and Vc be higher than the upper limit of the operation guarantee voltage of the image forming apparatus 1 and lower than the lower limit of the withstand voltage specification of the components of the power supply device 20. The AC voltages Va, Vb, and Vc are low in the order of Va < Vb < Vc. Thereby, a warning message is displayed when the AC voltage ACIN becomes equal to or higher than the value Vb, and after the display of the warning message, the supply of the AC voltage ACIN can be cut off when the AC voltage ACIN becomes equal to or higher than the value Vc.

[0038] Note that in order to improve the estimation accuracy of the AC voltage Va, it is desirable that the relationship between the change in the AC voltage Va and the temperature change indicated by the temperature information of the functional unit or the voltage change indicated by the current information of the functional unit be evaluated in advance using the actual image forming apparatus 1. When the estimation accuracy of the AC voltage Va is sufficiently high, the value Va may be set within the operation guarantee voltage. Further, since the AC voltages Vb and Vc lead to the stop of the operation of the image forming apparatus 1, it is necessary to set them to values at which a warning message is not displayed within the operation guarantee voltage in consideration of the detection accuracy of the voltage detection unit 27 and the power is not cut off.

[0039] Fig. 4 is a diagram showing an example of a warning message displayed on the operation panel 11a. When the AC voltage ACIN exceeds the value Vb shown in Fig. 3, the warning message shown in Fig. 4 is displayed on the operation panel 11a, allowing the user of the image forming apparatus 1 to recognize the occurrence of an overvoltage and to take appropriate action in response to the warning message.

[0040] Fig. 5 is a flow diagram showing an example of an operation for protecting the power supply device 20 of Fig. 2 from an overvoltage. The flow shown in Fig. 5 is carried out by the controller 12.

[0041] First, in step S101, if the switching unit 26 is turned on, the controller 12 carries out step S102, and if the switching unit 26 is turned off (in the case of the energy saving mode), the controller 12 carries out step S111.

[0042] In step S111, the controller 12 monitors the AC voltage ACIN for signs of overvoltage using the voltage estimation unit 12a. Next, in step S112, if the voltage estimation unit 12a detects signs of overvoltage, the controller 12 performs step S113, and if the voltage estimation unit 12a does not detect signs of overvoltage, the controller 12 returns to step S101.

[0043] In step S113, the controller 12 turns on the switching unit 26 and performs step S102. When the switching unit 26 is turned on, the voltage detection unit 27 starts detecting the AC voltage ACIN. That is, based on the detection of the symptom of an overvoltage by the voltage estimation unit 12a, the voltage detection unit 27 can accurately detect the value of the AC voltage ACIN.

[0044] In step S102, the controller 12 monitors the AC voltage ACIN based on the detection result of the AC voltage ACIN notified from the voltage detection unit 27. Next, in step S103, the controller 12 determines whether the AC voltage ACIN is an overvoltage or not, and if it is an overvoltage, performs step S104, and if it is not an overvoltage, returns to step S101. For example, the controller 12 may determine an overvoltage when the AC voltage ACIN is equal to or greater than the value Vb shown in FIG. 3.

[0045] In step S104, the controller 12 displays a warning message on the operation panel 11a. Furthermore, the voltage detection unit 27, which has detected the overvoltage, opens the power cutoff unit 22, and the operation shown in Fig. 5 ends. For example, the voltage detection unit 27 may open the power cutoff unit 22 when the AC voltage ACIN is equal to or greater than the value Vc shown in Fig. 3.

[0046] If the AC voltage ACIN is equal to or greater than the value Vb and less than the value Vc, a warning message is displayed but the power cutoff unit 22 is not opened. In this case, the user who sees the warning message can turn off the main power of the image forming apparatus 1, thereby ending the operation shown in FIG.

[0047] As described above, in the first embodiment, the operation of the voltage detection unit 27, which detects an overvoltage of the AC voltage ACIN, is performed during the normal mode and stopped during the energy-saving mode. This makes it possible to reduce the power consumption of the power supply device 20 and the image forming apparatus 1 during the energy-saving mode. In other words, it is possible to detect an overvoltage of the AC power supply while suppressing power consumption.

[0048] When the controller 12 turns on the switching unit 26 during the energy saving mode, the voltage detection unit 27 starts detecting an overvoltage of the AC voltage ACIN. This makes it possible to constantly monitor the AC voltage ACIN directly or indirectly while suppressing power consumption during the energy saving mode. If an overvoltage occurs, the supply of the AC voltage ACIN is cut off to protect the components of the power supply device 20 from damage.

[0049] When the notification from the voltage detection unit 27 indicates an overvoltage of the AC voltage ACIN, the controller 12 can notify the user of the image forming apparatus 1 of the occurrence of the overvoltage by displaying a warning message on the operation panel 11a of the operation unit 11. Upon seeing the warning message, the user of the image forming apparatus 1 can recognize the occurrence of the overvoltage and can take appropriate action in response to the warning message.

[0050] (Second embodiment) Fig. 6 is a block diagram showing an example of the main parts of an image forming apparatus 1A according to a second embodiment of the present invention. Elements similar to those in Fig. 2 are given the same reference numerals, and detailed description thereof will be omitted. The overall configuration of the image forming apparatus 1A shown in Fig. 6 is the same as that in Fig. 1, and the image forming apparatus 1A is, for example, a digital multifunction peripheral.

[0051] Image forming apparatus 1A has a power supply device 20A that is configured by removing status detection unit 28 from power supply device 20 in FIG. 1. Image forming apparatus 1A also has a switching unit 31A, a dehumidifying heater unit 32A, and a temperature detection unit 28A instead of status detection unit 28 in FIG. 1. Dehumidifying heater unit 32A is an example of a heat generating unit and a functional unit that generates heat in response to AC voltage ACIN. Temperature detection unit 28A is an example of a status detection unit.

[0052] The switching unit 31A is disposed between the output of the power supply cutoff unit 22 and the dehumidifying heater unit 32A. The switching unit 31A is set to a conductive state (ON) by a control signal received from the controller 12, and supplies the AC voltage ACIN output from the power supply cutoff unit 22 to the dehumidifying heater unit 32A.

[0053] Dehumidifying heater unit 32A is disposed, for example, in the storage space that houses paper feed tray 10, and prevents paper jams and curling that tend to occur when paper media in paper feed tray 10 become damp. Dehumidifying heater unit 32A operates while switching unit 31A in FIG. 1 is on. Note that dehumidifying heater unit 32A may be disposed not only in the storage space for paper feed tray 10, but also near image reading device 3 or photosensitive drum 6 to prevent condensation.

[0054] For example, the dehumidifying heater unit 32A is a nichrome wire heater that operates by receiving an AC voltage ACIN, and the rated voltage value varies depending on the shipping country of the image forming apparatus 1. For example, an image forming apparatus 1 used in Japan, where the AC voltage ACIN is 100V±10V, uses a dehumidifying heater unit 32A that includes a heater with a rated voltage of more than 110V. An image forming apparatus 1 used in Europe, where the AC voltage ACIN is 230V±10V, uses a dehumidifying heater unit 32A that includes a heater with a rated voltage of more than 240V. If a voltage equal to or greater than the rated voltage is continuously applied to the dehumidifying heater unit 32A, the heater may generate abnormal heat, causing a protective thermal fuse mounted in the dehumidifying heater unit 32A to melt and damage the dehumidifying heater unit 32A.

[0055] The dehumidifying heater unit 32A operates using the AC voltage ACIN supplied via the switching unit 31A during an energy saving mode in which the load 13 is not operating or when the image forming apparatus 1 is powered off. The controller 12 turns on the switching unit 31A to operate the dehumidifying heater unit 32A during an energy saving mode in which humidity tends to increase or when the image forming apparatus 1 is powered off.

[0056] Temperature detection unit 28A detects the temperature of dehumidifying heater unit 32A, which generates heat in response to AC voltage ACIN, and notifies temperature information indicating the detected temperature to controller 12. When the temperature of dehumidifying heater unit 32A indicated by the temperature information indicates a symptom of an overvoltage of AC voltage ACIN, controller 12 outputs a control signal to switching unit 26 to turn on switching unit 26, and outputs a control signal to switching unit 31A to turn off switching unit 31A.

[0057] The temperature of the dehumidifying heater unit 32A, which indicates a symptom of an overvoltage of the AC voltage ACIN, varies depending on the rated power of the dehumidifying heater unit 32A, the mounting structure of the dehumidifying heater unit 32A, the ambient temperature, etc. Therefore, it is desirable to evaluate in advance the temperature at which the voltage estimation unit 12a detects a symptom of an overvoltage of the AC voltage ACIN using the actual image forming apparatus 1.

[0058] Figure 7 is a flow diagram showing an example of an operation for protecting the power supply device 20A of Figure 6 from an overvoltage. The same steps as in Figure 5 are given the same step numbers, and detailed descriptions will be omitted. The flow shown in Figure 7 is performed by the controller 12. Figure 7 is the same as the operation of Figure 5, except that steps S121, S122, and S123 are performed instead of steps S111, S112, and S113 of Figure 5.

[0059] If the controller 12 has turned off the switching unit 26 in step S101 (in the energy saving mode), the controller 12 detects the temperature of the dehumidifying heater unit 32A based on the temperature information from the temperature detection unit 28A in step S121. Note that the controller 12 may determine whether the switching unit 31A is turned on before performing step S121, and perform step S121 only if the switching unit 31A is turned on.

[0060] Next, in step S122, if the temperature detected in step S121 is equal to or higher than a preset threshold, the controller 12 (voltage estimation unit 12a) determines that there is a sign of an overvoltage in the AC voltage ACIN, and executes step S123. If the detected temperature is lower than the threshold, the controller 12 (voltage estimation unit 12a) determines that there is no sign of an overvoltage in the AC voltage ACIN, and returns to step S101. In step S123, the controller 12 turns on the switching unit 26, and executes step S102. The operations from step S102 onwards are the same as those in FIG. 5.

[0061] Figure 8 is a flow diagram showing another example of the operation of protecting the power supply device 20A of Figure 6 from an overvoltage. The same step numbers are used for the same processes as in Figure 5, and detailed explanations will be omitted. Figure 8 is the same as the operation of Figure 5, except that steps S131-S137 are performed instead of steps S111, S112, and S113 of Figure 5.

[0062] If the switching unit 26 is turned off (in the energy saving mode) in step S101, the controller 12 performs step S131. In step S131, the controller 12 sets the variable n to 0. Note that before performing step S131, the controller 12 may determine whether the switching unit 31A is turned on, and perform step S131 only if the switching unit 31A is turned on.

[0063] Next, in step S132, the controller 12 detects the temperature of the dehumidifying heater unit 32A based on the temperature information from the temperature detection unit 28A. Next, in step S133, the controller 12 adds 1 to the variable n. Next, in step S134, if the variable n is 2, the controller 12 performs step S136, and if the variable n is not 2 (i.e., if it is 1), the controller 12 performs step S135.

[0064] In step S135, the controller 12 waits for t seconds to elapse, and then returns to step S132. In step S136, the controller 12 (voltage estimation unit 12a) obtains the difference between the temperatures detected in the two executions of step S132 as the temperature rise gradient. If the temperature rise gradient is equal to or greater than a preset threshold, the controller 12 (voltage estimation unit 12a) determines that there is a sign of an overvoltage in the AC voltage ACIN, and executes step S137. If the temperature rise gradient is less than the threshold, the controller 12 (voltage estimation unit 12a) determines that there is no sign of an overvoltage in the AC voltage ACIN, and returns to step S101. In step S137, the controller 12 turns on the switching unit 26, and executes step S102. The operations from step S102 onwards are the same as those in FIG. 5.

[0065] As described above, the second embodiment can also achieve the same effects as the first embodiment. For example, the operation of the voltage detection unit 27, which detects an overvoltage of the AC voltage ACIN, is performed during normal mode and stopped during energy saving mode. This makes it possible to detect an overvoltage of the AC power supply while suppressing power consumption. Furthermore, in the second embodiment, it is possible to determine whether or not there is a sign of an overvoltage of the AC voltage ACIN based on the temperature or temperature rise gradient of the dehumidifying heater unit 32A, which is operable during energy saving mode.

[0066] (Third embodiment) Fig. 9 is a block diagram showing an example of the main parts of an image forming apparatus 1B according to a third embodiment of the present invention. The same elements as those in Fig. 2 are given the same reference numerals, and detailed description thereof will be omitted. The overall configuration of the image forming apparatus 1B shown in Fig. 9 is the same as that in Fig. 1, and the image forming apparatus 1B is, for example, a digital multifunction peripheral.

[0067] Image forming apparatus 1B has a power supply device 20B configured by adding a current detection unit 28B to power supply device 20 in FIG. 1. Current detection unit 28B is disposed between electrolytic capacitor 24 and voltage line V1 connected to the output of rectifier circuit 23, and detects the current flowing through electrolytic capacitor 24. Current detection unit 28B notifies controller 12 of current information indicating the detected current. Current detection unit 28B is an example of a state detection unit that detects the current flowing through electrolytic capacitor 24.

[0068] During the energy saving mode, when the current flowing through the electrolytic capacitor 24, which is indicated by the current information, indicates an indication of an overvoltage of the AC voltage ACIN, the controller 12 outputs a control signal to the switching unit 26 to turn on the switching unit 26. As a result, similar to the first embodiment, the voltage detection unit 27, which has stopped operating during the energy saving mode, can be operated when the value of the AC voltage ACIN indicates an indication of an overvoltage.

[0069] Fig. 10 is a flow diagram showing an example of an operation for protecting the power supply device 20B of Fig. 9 from an overvoltage. The same step numbers are used for the same processes as in Fig. 5, and detailed descriptions will be omitted. The flow shown in Fig. 10 is performed by the controller 12. Fig. 10 is the same as the operation of Fig. 5, except that steps S141, S142, and S143 are performed instead of steps S111, S112, and S113 of Fig. 5.

[0070] If the controller 12 has turned off the switching unit 26 in step S101 (in the energy saving mode), then in step S141, the controller 12 detects the current flowing through the electrolytic capacitor 24 based on the current information from the current detection unit 28B. Next, in step S142, if the current detected in step S141 is equal to or greater than a preset threshold, the controller 12 (voltage estimation unit 12a) determines that there is a sign of an overvoltage in the AC voltage ACIN, and executes step S143. If the detected current is less than the threshold, the controller 12 (voltage estimation unit 12a) determines that there is no sign of an overvoltage in the AC voltage ACIN, and returns to step S101. In step S143, the controller 12 turns on the switching unit 26 and executes step S102. The operations from step S102 onwards are the same as those in FIG. 5.

[0071] As described above, the third embodiment can also achieve the same effects as the first embodiment. For example, the operation of the voltage detection unit 27, which detects an overvoltage of the AC voltage ACIN, is performed during normal mode and stopped during energy saving mode. This makes it possible to detect an overvoltage of the AC power supply while suppressing power consumption. Furthermore, in the third embodiment, it is possible to determine whether or not there is a sign of an overvoltage of the AC voltage ACIN based on the value of the current flowing through the electrolytic capacitor 24, which is charged and discharged even during energy saving mode.

[0072] (Fourth embodiment) Fig. 11 is a block diagram showing an example of the main parts of an image forming apparatus 1C according to a fourth embodiment of the present invention. Elements similar to those in Fig. 2 are given the same reference numerals, and detailed description thereof will be omitted. The overall configuration of the image forming apparatus 1C shown in Fig. 11 is the same as that in Fig. 1, and the image forming apparatus 1C is, for example, a digital multifunction peripheral.

[0073] Image forming apparatus 1C has a power supply device 20C configured by adding a temperature detection unit 28C to power supply device 20 in FIG. 1. Temperature detection unit 28C is disposed near electrolytic capacitor 24 and detects the temperature of electrolytic capacitor 24. Temperature detection unit 28C notifies controller 12 of temperature information indicating the detected temperature. Current detection unit 28B is an example of a status detection unit that detects the temperature of electrolytic capacitor 24.

[0074] During the energy saving mode, when the temperature of the electrolytic capacitor 24 indicated by the voltage information indicates an indication of an overvoltage of the AC voltage ACIN, the controller 12 outputs a control signal to the switching unit 26 to turn on the switching unit 26. As a result, similar to the first and third embodiments, the voltage detection unit 27, which has stopped operating during the energy saving mode, can be operated when the value of the AC voltage ACIN indicates an indication of an overvoltage.

[0075] Figure 12 is a flow diagram showing an example of an operation for protecting the power supply device 20C of Figure 11 from an overvoltage. The same step numbers are used for the same processes as in Figure 5, and detailed descriptions will be omitted. The flow shown in Figure 12 is performed by the controller 12. Figure 12 is the same as the operation of Figure 5, except that steps S151, S152, and S153 are performed instead of steps S111, S112, and S113 of Figure 5.

[0076] If the controller 12 has turned off the switching unit 26 in step S101 (in the energy saving mode), then in step S151, the controller 12 detects the temperature of the electrolytic capacitor 24 based on the temperature information from the temperature detection unit 28C. Next, in step S152, if the temperature detected in step S151 is equal to or higher than a preset threshold, the controller 12 (voltage estimation unit 12a) determines that there is a sign of an overvoltage in the AC voltage ACIN, and executes step S153. If the detected temperature is lower than the threshold, the controller 12 (voltage estimation unit 12a) determines that there is no sign of an overvoltage in the AC voltage ACIN, and returns to step S101. In step S153, the controller 12 turns on the switching unit 26 and executes step S102. The operations from step S102 onwards are the same as those in FIG. 5.

[0077] As described above, the fourth embodiment can also achieve the same effects as the first embodiment. For example, the operation of the voltage detection unit 27, which detects an overvoltage of the AC voltage ACIN, is performed during normal mode and stopped during energy saving mode. This makes it possible to detect an overvoltage of the AC power supply while suppressing power consumption. Furthermore, in the fourth embodiment, it is possible to determine whether or not there is a sign of an overvoltage of the AC voltage ACIN based on the temperature of the electrolytic capacitor 24, which is charged and discharged even during energy saving mode.

[0078] Fig. 13 is a block diagram showing an example of the hardware configuration of the controller 12 of Fig. 1 and Fig. 2. The controller 12 has a CPU 121, a ROM (Read Only Memory) 122, and a RAM (Random Access Memory) 123. The controller 12 also has an input interface unit 124, an output interface unit 125, an input / output interface unit 126, and a communication interface unit 127.

[0079] For example, the CPU 121, ROM 122, RAM 123, input interface unit 124, output interface unit 125, input / output interface unit 126, and communication interface unit 127 are interconnected via a bus BUS.

[0080] The CPU 121 executes various programs such as an OS (Operating System) and applications. The ROM 122 stores basic programs and various parameters that enable the various programs to be executed by the CPU 121. The RAM 123 stores the various programs executed by the CPU 121 and data used by the programs. For example, the various programs may include an image processing program that performs image processing on an original image read by the image reading device 3 and a power supply control program that controls the power supply device 20. The various programs may also include a control program that causes the controller 12 to operate as a voltage estimation unit 12a.

[0081] For example, input devices 41 such as the image reading device 3 and an input unit mounted on the operation unit 11 of the image forming apparatus 1 are connected to the input interface unit 124. An output device 42 such as the operation panel 11a mounted on the operation unit 11 is connected to the output interface unit 125. An input / output device 43 such as an auxiliary storage device and a recording medium is connected to the input / output interface unit 126. The communication interface unit 127 can connect the image forming apparatus 1 to a network or the like.

[0082] When various programs such as an image processing program or a power supply control program are stored on a recording medium, the programs may be transferred from the recording medium to the RAM 123 or the like via the input / output interface unit 126 to which the recording medium is connected.

[0083] For example, aspects of the present invention are as follows. <1> an image forming unit that forms an image based on an AC voltage input from an external device; a voltage detection unit that detects the value of the AC voltage; a switching unit that switches a current path for the AC voltage to the voltage detection unit between a conductive state and a cut-off state; a functional unit that generates heat or flows current in response to the AC voltage; a state detection unit that detects the temperature or current of the functional unit; a control unit that estimates the value of the AC voltage based on the temperature or current detected by the state detection unit, and switches the switching unit from a cut-off state to a conductive state when the estimated value of the AC voltage indicates a sign of overvoltage. An image forming apparatus comprising: <2> the functional unit is a heat generating unit that generates heat in response to the AC voltage, the state detection unit detects the temperature of the heat generating unit, The control unit determines that the value of the AC voltage indicates a sign of overvoltage when the temperature detected by the state detection unit is equal to or higher than a threshold value. Characterized by <1> 2. The image forming apparatus according to claim 1 . <3> the functional unit is a heat generating unit whose temperature changes in response to a change in the AC voltage, the state detection unit detects the temperature of the heat generating unit, The control unit determines that the value of the AC voltage indicates a symptom of an overvoltage when a temperature rise gradient of the temperature detected by the state detection unit multiple times at time intervals is equal to or greater than a threshold value. Characterized by <1> 2. The image forming apparatus according to claim 1 . <4> the functional unit is an electrolytic capacitor that stores electricity based on the AC voltage, the state detection unit detects a current flowing through the electrolytic capacitor; The control unit determines that the value of the AC voltage indicates a sign of overvoltage when the current detected by the state detection unit is equal to or greater than a threshold value. Characterized by <1> 2. The image forming apparatus according to claim 1 . <5> the functional unit is an electrolytic capacitor that stores electricity based on the AC voltage, the state detection unit detects the temperature of the electrolytic capacitor; The control unit determines that the value of the AC voltage indicates a sign of overvoltage when the temperature detected by the state detection unit is equal to or higher than a threshold value. Characterized by <1> 2. The image forming apparatus according to claim 1 . <6> A display unit capable of displaying information is provided. When the control unit determines that the value of the AC voltage indicates a sign of overvoltage, the control unit causes the display unit to display a warning message. Characterized by <1> Or <5> 10. The image forming apparatus according to claim 1, wherein <7> a power cutoff unit that is provided in the AC voltage input unit and is capable of cutting off the input of the AC voltage; The voltage detection unit causes the power cutoff unit to cut off input of the AC voltage when detecting that the AC voltage is an overvoltage. Characterized by <1> Or <6> 10. The image forming apparatus according to claim 1, wherein <8> an energy saving mode in which image formation by the image forming unit is stopped; the control unit sets the switching unit to a cut-off state during the energy saving mode, The voltage detection unit stops detecting AC voltage during the energy saving mode. Characterized by <1> Or <7> 10. The image forming apparatus according to claim 1, wherein <9> The control unit estimates a value of the AC voltage based on the temperature or current detected by the state detection unit during the energy saving mode, and when the estimated value of the AC voltage shows a sign of overvoltage, switches the switching unit from a cut-off state to a conductive state. Characterized by <8> 2. The image forming apparatus according to claim 1 . <10> A method for controlling an image forming apparatus having an image forming unit that forms an image based on an AC voltage input from an external source, and a functional unit that generates heat or flows current in response to the AC voltage, comprising: a voltage detection unit included in the image forming apparatus detects a value of the AC voltage; a switching unit included in the image forming apparatus switches a current path for the AC voltage to the voltage detection unit between a conductive state and a cut-off state; a state detection unit included in the image forming apparatus detects a temperature or a current of the functional unit; A control unit of the image forming apparatus estimates a value of the AC voltage based on the temperature or current detected by the state detection unit, and when the estimated value of the AC voltage indicates a sign of overvoltage, switches the switching unit from a cut-off state to a conductive state. A control method for an image forming apparatus, comprising:

[0084] 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]

[0085] 1. Image forming device 2 Automatic document feeder 3. Image reading device 4 writing units 5 Printer unit 6 Photosensitive drum 7. Developing device 8 conveyor belt 9 Fixing device 10 Paper tray 11 Control section 11a Operation panel 12 Controllers 12a Voltage estimation section 13 Load 20 Power supply 21. Fuse 22 Power cutoff section 23 Rectifier circuit 24 electrolytic capacitors 25 DC / DC converter 26 Switching section 27 Voltage detection unit 28 Status detection unit 28A Temperature detection unit 28B Current detection unit 28C Temperature detection unit 31A Switching Unit 32A Dehumidifying heater 41 Input Devices 42 Output Devices 43 Input / Output Devices 121 CPU 122 ROM 123 RAM 124 Input interface section 125 Output interface section 126 Input / Output Interface Section 127 Communication interface section 200 control board AC alternating current power supply ACIN AC voltage BUS V1 voltage line, DC voltage [Prior art documents] [Patent documents]

[0086] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-033279 [Patent Document 2] Patent Publication No. 2021-164345

Claims

1. an image forming unit that forms an image based on an AC voltage input from an external device; a voltage detection unit that detects the value of the AC voltage; a switching unit that switches a current path for the AC voltage to the voltage detection unit between a conductive state and a cut-off state; a functional unit that generates heat or flows current in response to the AC voltage; a state detection unit that detects the temperature or current of the functional unit; a control unit that estimates the value of the AC voltage based on the temperature or current detected by the state detection unit, and switches the switching unit from a cut-off state to a conductive state when the estimated value of the AC voltage indicates a sign of overvoltage. An image forming apparatus comprising:

2. the functional unit is a heat generating unit that generates heat in response to the AC voltage, the state detection unit detects the temperature of the heat generating unit, The control unit determines that the value of the AC voltage indicates a sign of overvoltage when the temperature detected by the state detection unit is equal to or higher than a threshold value.

2. The image forming apparatus according to claim 1, wherein:

3. the functional unit is a heat generating unit whose temperature changes in response to a change in the AC voltage, the state detection unit detects the temperature of the heat generating unit, The control unit determines that the value of the AC voltage indicates a symptom of an overvoltage when a temperature rise gradient of the temperature detected by the state detection unit multiple times at time intervals is equal to or greater than a threshold value.

2. The image forming apparatus according to claim 1, wherein:

4. the functional unit is an electrolytic capacitor that stores electricity based on the AC voltage, the state detection unit detects a current flowing through the electrolytic capacitor; The control unit determines that the value of the AC voltage indicates a sign of overvoltage when the current detected by the state detection unit is equal to or greater than a threshold value.

2. The image forming apparatus according to claim 1, wherein:

5. the functional unit is an electrolytic capacitor that stores electricity based on the AC voltage, the state detection unit detects the temperature of the electrolytic capacitor; The control unit determines that the value of the AC voltage indicates a sign of overvoltage when the temperature detected by the state detection unit is equal to or higher than a threshold value.

2. The image forming apparatus according to claim 1, wherein:

6. A display unit capable of displaying information is provided. When the control unit determines that the value of the AC voltage indicates a sign of overvoltage, the control unit causes the display unit to display a warning message.

6. The image forming apparatus according to claim 1, wherein:

7. a power cutoff unit that is provided in the AC voltage input unit and is capable of cutting off the input of the AC voltage; The voltage detection unit causes the power cutoff unit to cut off input of the AC voltage when detecting that the AC voltage is an overvoltage.

6. The image forming apparatus according to claim 1, wherein:

8. an energy saving mode in which image formation by the image forming unit is stopped; the control unit sets the switching unit to a cut-off state during the energy saving mode, The voltage detection unit stops detecting the AC voltage during the energy saving mode.

6. The image forming apparatus according to claim 1, wherein:

9. The control unit estimates a value of the AC voltage based on the temperature or current detected by the state detection unit during the energy saving mode, and when the estimated value of the AC voltage shows a sign of overvoltage, switches the switching unit from a cut-off state to a conductive state.

9. The image forming apparatus according to claim 8, wherein:

10. A method for controlling an image forming apparatus having an image forming unit that forms an image based on an AC voltage input from an external source, and a functional unit that generates heat or flows current in response to the AC voltage, comprising: a voltage detection unit included in the image forming apparatus detects a value of the AC voltage; a switching unit included in the image forming apparatus switches a current path for the AC voltage to the voltage detection unit between a conductive state and a cut-off state; a state detection unit included in the image forming apparatus detects a temperature or a current of the functional unit; A control unit of the image forming apparatus estimates a value of the AC voltage based on the temperature or current detected by the state detection unit, and when the estimated value of the AC voltage indicates a sign of overvoltage, switches the switching unit from a cut-off state to a conductive state. A control method for an image forming apparatus, comprising:

Images