Power supply unit and image processing unit
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- KONICA MINOLTA INC
- Filing Date
- 2025-01-17
- Publication Date
- 2026-07-30
Smart Images
Figure 2026123432000001_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a power supply device and an image forming apparatus, and more particularly to a power supply device connected to any of a plurality of types of commercial power supplies and an image processing apparatus including the power supply device.
[0002] An image system device includes a power supply device connected to a commercial power supply. This power supply device may be connectable to any of a plurality of types of commercial power supplies. The plurality of types of commercial power supplies have different voltages or frequencies. On the other hand, a momentary power outage may occur in the commercial power supply. The power supply device includes a power storage unit such as a capacitor to cope with a momentary power outage.
[0003] For example, in Japanese Patent Laid-Open No. 2015-138112, the output of a first power supply with a constant voltage output using power supplied from the outside as an input source and the output of a second power supply with the output of a storage battery as an input source are connected in parallel, and the power from the first power supply and the power from the second power supply are simultaneously supplied to a load. A power supply device includes a constant voltage load power supply unit that supplies power to a constant voltage load, a heater power supply unit that supplies power to a heater, a DC internal bus that connects the first power supply, the second power supply, the constant voltage load power supply unit, and the heater power supply unit, a load power detection unit that detects the load power of the DC internal bus, a power supply control unit that controls the output of the second power supply, and an input power detection unit that detects the input power input to the first power supply from the outside. The power supply control unit controls the output of the second power supply so that the input power detected by the input power detection unit is equal to the first threshold value.
[0004] However, when the power input from the outside is instantaneously interrupted, power is supplied only from the second power supply to the constant voltage load power supply unit and the heater power supply unit. Therefore, the power storage capacity of the storage battery has to be increased. For this reason, there is a problem that the product cost increases.
Prior Art Documents
Patent Documents
[0005] [Patent Document 1] Japanese Patent Publication No. 2015-138112 [Overview of the project] [Problems that the invention aims to solve]
[0006] This invention was made to solve the problems described above, and one of its objectives is to provide a power supply device that suppresses increases in product costs.
[0007] Another objective of this invention is to provide an image processing apparatus that suppresses increases in product costs. [Means for solving the problem]
[0008] To achieve the above-mentioned objective, according to one aspect of this invention, the power supply device comprises: an AC input section to which any of a plurality of commercial power sources can be connected; a power storage section; a power factor correction circuit that converts the AC input to the AC input section into DC of a predetermined voltage and outputs it to the parallel-connected power storage section, an external first load, and a second load; and a switching section that switches to a state in which power is supplied from the power storage section to the first load and not supplied from the power storage section to the second load while the commercial power source connected to the AC input section is momentarily out of service.
[0009] According to another aspect of this invention, the image processing apparatus comprises the power supply, first load, and second load described above. [Brief explanation of the drawing]
[0010] [Figure 1] This is a schematic cross-sectional view showing an example of the internal configuration of an MFP in one of these embodiments. [Figure 2] This block diagram shows an overview of the hardware configuration of the MFP in this embodiment. [Figure 3] This figure shows an example of the internal circuit configuration of the power supply device in this embodiment. [Figure 4]This figure shows an example of the voltage in the circuit during a momentary power outage in the power supply device of this embodiment. [Figure 5] This figure shows an example of the voltage in the comparative example circuit. [Figure 6] This figure shows an example of the internal circuit configuration of the power supply in the first modified example. [Figure 7] This figure shows an example of the voltage in the circuit during a momentary power outage in the power supply unit in the first modified example. [Figure 8] This figure shows an example of the internal circuit configuration of the power supply unit in the second modified example. [Figure 9] This figure shows an example of the voltage in the circuit during a momentary power outage in the power supply unit in the second modified example. [Modes for carrying out the invention]
[0011] Embodiments of the present invention will be described below with reference to the drawings. In the following description, identical parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated.
[0012] Figure 1 is a schematic cross-sectional view showing an example of the internal configuration of an MFP in one embodiment. The MFP (MultiFunction Peripheral) 100 is an example of an image processing device. Referring to Figure 1, the MFP 100 includes an automatic document transport device 120, a document reading unit 130 for reading documents, an image forming unit 140 for forming images on paper based on image data, and a paper feeding unit 150 for supplying paper to the image forming unit 140.
[0013] The automatic document transport device 120 automatically transports multiple documents placed on the document tray one by one to a predetermined document reading position set on the platen glass of the document reading unit 130. The automatic document transport device 120 then discharges the documents from which the image formed on the documents has been read by the document reading unit 130 into the document output tray.
[0014] The document scanning unit 130 exposes the image of the document placed on the document glass 11 to an exposure lamp 13 attached to a slider 12 that moves below it. The reflected light from the document is guided to the lens 16 by a mirror 14 and two reflective mirrors 15, 15A, and an image is formed on the CCD (Charge Coupled Devices) sensor 18.
[0015] The reflected light formed on the CCD sensor 18 is converted into image data as an electrical signal within the CCD sensor 18. The image data is converted into printable data for cyan (C), magenta (M), yellow (Y), and black (K), and output to the image forming unit 140.
[0016] The image forming unit 140 includes image forming units 20Y, 20M, 20C, and 20K for yellow, magenta, cyan, and black, respectively. Here, "Y", "M", "C", and "K" represent yellow, magenta, cyan, and black, respectively. An image is formed when at least one of the image forming units 20Y, 20M, 20C, and 20K is driven. A full-color image is formed when all of the image forming units 20Y, 20M, 20C, and 20K are driven. Printing data for yellow, magenta, cyan, and black are input to the image forming units 20Y, 20M, 20C, and 20K, respectively. The only difference between the image forming units 20Y, 20M, 20C, and 20K is the color of the toner they handle, so here we will describe the image forming unit 20Y for forming a yellow image.
[0017] The image forming unit 20Y includes an exposure device 21Y, a photosensitive drum 23Y, a charging roller 22Y, a developing device 24Y, and a primary transfer roller 25Y. Around the photosensitive drum 23Y, a charging roller 22Y, an exposure device 21Y, a developing device 24Y, a primary transfer roller 25Y, and a drum cleaning blade 27Y are arranged in order along the rotation direction of the photosensitive drum 23Y. The exposure device 21Y receives yellow printing data input. The photosensitive drum 23Y is an image carrier. The charging roller 22Y uniformly charges the surface of the photosensitive drum 23Y. The primary transfer roller 25Y transfers the toner image formed on the photosensitive drum 23Y onto the intermediate transfer belt 30, which is an image carrier, by the action of an electric field force.
[0018] After the photosensitive drum 23Y is charged by the charging roller 22Y, it is irradiated with laser light emitted by the exposure device 21Y. The exposure device 21Y exposes the image corresponding portion on the surface of the photosensitive drum 23Y. Thereby, an electrostatic latent image is formed on the photosensitive drum 23Y. Subsequently, the developing device 24Y develops the electrostatic latent image formed on the photosensitive drum 23Y with charged toner. Specifically, toner is placed on the electrostatic latent image formed on the photosensitive drum 23Y by the action of an electric field force, whereby a toner image is formed on the photosensitive drum 23Y. The toner image formed on the photosensitive drum 23Y is transferred onto the intermediate transfer belt 30, which is an image carrier, by the primary transfer roller 25Y by the action of an electric field force. The toner remaining on the photosensitive drum 23Y without being transferred is removed from the photosensitive drum 23Y by the drum cleaning blade 27Y.
[0019] The intermediate transfer belt 30 is suspended by a driving roller 33 and a driven roller 34 so as not to slacken. When the driving roller 33 rotates counterclockwise in the figure, the intermediate transfer belt 30 rotates counterclockwise in the figure at a predetermined speed. As the intermediate transfer belt 30 rotates, the driven roller 34 rotates counterclockwise.
[0020] As a result, the image forming units 20Y, 20M, 20C, and 20K transfer the toner images onto the intermediate transfer belt 30 in order. The timing for each of the image forming units 20Y, 20M, 20C, and 20K to transfer the toner image onto the intermediate transfer belt 30 is adjusted based on the detection of the reference mark attached to the intermediate transfer belt 30. Thereby, the toner images of yellow, magenta, cyan, and black are superimposed on the intermediate transfer belt 30.
[0021] Paper sheets of different sizes are set in the paper feed cassettes 35 and 35A, respectively. The paper sheets housed in the paper feed cassettes 35 and 35A are supplied to the conveyance path by the pickup rollers 36 and 36A respectively attached to the paper feed cassettes 35 and 35A, and are sent to the timing roller 31 by the paper feed roller 37.
[0022] The paper sheet conveyed by the timing roller 31 is conveyed to the nip portion where the intermediate transfer belt 30 and the secondary transfer belt 26 are in contact. The toner image formed on the intermediate transfer belt 30 is transferred onto the paper sheet by the action of the electric field force by the secondary transfer belt 26 which is a transfer member. The paper sheet onto which the toner image is transferred is conveyed to the fixing device 70.
[0023] The fixing device 70 includes a pressure roller 71 and a heating roller 73. The heating roller 73 is a member having a hollow cylindrical shape, and its rotating shaft is supported by the main body case. The heating roller 73 incorporates a DC fixing lamp 75 inside. The inner diameter of the heating roller 73 is set to a size where the DC fixing lamp 75 does not come into contact. The heating roller 73 is made of stainless steel. Note that the heating roller 73 may be made of aluminum.
[0024] The DC fixing lamp 75 is, for example, a halogen heater. In the present embodiment, two halogen heaters having different emission lengths are used as the heat source 54. Note that the DC fixing lamp 75 is not limited to a halogen heater, and a resistance heating element or IH (Induction Heating) may be used.
[0025] The DC fixing lamp 75 generates heat, which heats the heating roller 73, causing its temperature to rise. A thermistor (not shown) is placed at a predetermined distance from the heating roller 73. The thermistor detects the temperature of the heating roller 73. The DC fixing lamp 75 is controlled to turn on or off according to the temperature detected by the thermistor, thereby controlling the heating roller 73 to reach a predetermined temperature.
[0026] The pressure roller 71 is cylindrical and positioned opposite the heating roller 73. The pressure roller 71 is biased toward the heating roller 73. As a result, the paper on which the toner image has been transferred is heated and pressurized by the pressure roller 71 and the heating roller 73 as it passes between them. This melts the toner and fixes it to the paper. The paper is then transported to the output tray 39.
[0027] When forming a full-color image, the MFP100 drives all four image forming units 20Y, 20M, 20C, and 20K. However, when forming a monochrome image, it drives only one of the four image forming units 20Y, 20M, 20C, and 20K. It is also possible to form an image by combining two or more of the two image forming units 20Y, 20M, 20C, and 20K. Here, we will describe an example in which the MFP100 employs a tandem system equipped with image forming units 20Y, 20M, 20C, and 20K that form each of the four toners on the paper. However, the MFP100 may also form an image using a four-cycle system in which a single photosensitive drum transfers the four toners sequentially onto the paper.
[0028] Figure 2 is a block diagram illustrating the hardware configuration of the MFP in this embodiment. Referring to Figure 2, the MFP 100 includes a main circuit 110, a power supply 50, an automatic document transport device 120, a document reading unit 130, an image forming unit 140, a paper feeding unit 150, an operation panel 160, and an external storage device 170. The operation panel 160 is the user interface.
[0029] The power supply unit 50 is connected to the commercial power supply 200 and converts AC to DC at a predetermined voltage. The power supply unit 50 supplies DC at a predetermined voltage to the main circuit 110 and the DC fixing lamp 75 of the image forming unit 140. Although not shown in the figures, the power supply unit 50 may also supply AC or DC from the commercial power supply 200 to the automatic document transport device 120, document reading unit 130, image forming unit 140, paper feeding unit 150, operation panel 160, and external storage device 170.
[0030] The main circuit 110 includes a CPU 111, a communication interface (I / F) unit 112, a ROM 113, a RAM 114, an HDD 115, and a facsimile unit 116.
[0031] ROM 113 stores the program executed by CPU 111, or the data necessary to execute that program. RAM 114 is non-volatile memory. RAM 114 is used as a workspace when CPU 111 executes programs. RAM 114 also temporarily stores scanned images that are continuously sent from document reading unit 130.
[0032] The communication interface 112 is an interface for connecting the MFP100 to a network. The communication interface 112 communicates with computers connected to the network using communication protocols such as TCP (Transmission Control Protocol) or FTP (File Transfer Protocol).
[0033] The HDD115 is a high-capacity storage device. A solid-state drive (SSD) may be used instead of the HDD115. The CPU111 is connected to the automatic document transport device 120, the document reading unit 130, the image forming unit 140, the paper feeding unit 150, and the operation panel 160, and controls the entire MFP100.
[0034] The facsimile unit 116 is connected to the Public Switched Telephone Network (PSTN) and transmits facsimile data to the PSTN, and also receives facsimile data from the PSTN. The facsimile unit 116 converts the received facsimile data into printable data for the image forming unit 140 and outputs it to the image forming unit 140. As a result, the image forming unit 140 forms an image on paper from the facsimile data received by the facsimile unit 116. The facsimile unit 116 may also store the received facsimile data in the HDD 115. Alternatively, the facsimile unit 116 converts the data stored in the HDD 115 back into facsimile data and transmits it to a facsimile device connected to the PSTN.
[0035] The control panel 160 is located on the top surface of the MFP 100. The control panel 160 includes a display unit and an operation unit. The display unit is, for example, a liquid crystal display (LCD) and displays instruction menus for the user, information about acquired image data, etc. Instead of an LCD, any device that displays images may be used, such as an organic EL display. The operation unit 163 includes a touch panel and a plurality of hard keys. The hard keys are, for example, contact switches.
[0036] The external storage device 170 is controlled by the CPU 111 and has a CD-ROM 171 installed in it. In this embodiment, an example is described in which the CPU 111 executes a program stored in ROM 113. Alternatively, the CPU 111 may control the external storage device 170 to read a program for execution from the CD-ROM 171, store the read program in RAM 114, and then execute it.
[0037] Furthermore, the recording medium for storing the program to be executed by the CPU 111 is not limited to the CD-ROM 171; other media such as flexible disks, cassette tapes, optical disks, and semiconductor memory may also be used. Optical disks include MO (Magnetic Optical Disc), MD (MiniDisc), and DVD (Digital Versatile Disc). Semiconductor memory includes IC cards, optical cards, mask ROMs, and EPROMs (Erasable Programmable ROMs).
[0038] Furthermore, the CPU 111 may load programs stored in the HDD 115 into the RAM 114 and execute them on the CPU 111. Programs stored in the HDD 115 include programs downloaded by the CPU 111 from a computer connected to the Internet, or programs written to the HDD 115 by a computer connected to the Internet. The term "program" here includes not only programs that can be directly executed by the CPU 111, but also source programs, compressed programs, encrypted programs, and the like.
[0039] Figure 3 shows an example of the internal circuit configuration of the power supply unit in this embodiment. Referring to Figure 3, the power supply unit 50 includes an NF circuit 51 connected to a commercial power supply 200, a rectifier circuit 53, a PFC circuit 55, a diode 59, and a capacitor 57. The NF circuit 51 is compatible with multiple types of commercial power supplies. There are multiple types of commercial power supplies, differing in voltage and frequency. The NF circuit 51 is connected to one of the multiple types of commercial power supplies. Here, we will explain using the case where the NF circuit 51 is connected to one of the multiple types of commercial power supplies 200 as an example.
[0040] The NF circuit 51 is a noise filter that removes harmonic noise from the AC power supplied from the commercial power supply 200. The rectifier circuit 53 is connected to the NF circuit 51 and receives the output of the NF circuit 51. The rectifier circuit 53 rectifies the output of the NF circuit 51 and converts it into a DC voltage. The rectifier circuit 53 includes, for example, a full-wave rectifier circuit using diodes and a smoothing circuit provided after the full-wave rectifier circuit. The smoothing circuit smooths the pulsating current into DC.
[0041] The PFC (Power Factor Collect) circuit 55 receives the output of the rectifier circuit 53. The PFC circuit 55 receives the output of the rectifier circuit 53, generates a DC voltage of a predetermined value, and improves the power factor.
[0042] The output of the PFC circuit 55 is connected to the anode of diode 59. The cathode of diode 59 is connected to the first load 210. The second load 220 is connected between the PFC circuit 55 and the anode of diode 59. One end of capacitor 57 is connected between the cathode of diode 59 and the first load 210. The other end of capacitor 57 is grounded. Capacitor 57, the first load 210, and the second load 220 are connected in parallel to the PFC circuit 55.
[0043] The first load 210 includes a DC / DC circuit 211 and a main circuit 110. The DC / DC circuit 211 is a circuit that transforms the DC voltage input from the PFC circuit 55. The DC / DC circuit 211 converts the DC voltage input from the PFC circuit 55 into a voltage determined in accordance with the main circuit 110.
[0044] The second load 220 includes a lamp drive circuit 77 and a DC fixing lamp 75. The lamp drive circuit 77 receives temperature input from a thermistor located at a predetermined distance from the heating roller 73. The lamp drive circuit 77 controls the DC fixing lamp 75 to turn on / off according to the temperature detected by the thermistor.
[0045] Figure 4 shows an example of the voltages in the circuit during a momentary power outage in the power supply unit of this embodiment. In Figure 4, from top to bottom, the input voltage of the NF circuit 51, the input voltage of the DC / DC circuit 211, the output voltage of the DC / DC circuit 211, and the input voltage of the DC fixing lamp 75 are shown. Note that the input voltage of the DC fixing lamp 75 is the voltage when it is switched on by the lamp drive circuit 77.
[0046] This example illustrates a case where a momentary power outage occurs in the commercial power supply 200, where power is momentarily unavailable for 20ms between time t1 and time t2. The input voltage of the NF circuit 51 is affected during the momentary power outage, as power is not supplied from the commercial power supply 200.
[0047] Referring to Figure 3, when AC power is not input to the NF circuit 51 from the commercial power supply 200, the output voltage of the PFC circuit 55 decreases. As a result, the capacitor 57 begins to discharge, and a DC voltage is applied to the DC / DC circuit 211. Therefore, as shown in the second row of Figure 4, the input voltage of the DC / DC circuit 211 gradually decreases, but is maintained above the lower limit value VT1. The output voltage of the DC / DC circuit 211 maintains a constant value V1 even during the momentary power outage. The power supplied from the capacitor 57 is interrupted by the diode 59 and is not supplied to the lamp drive circuit 77. Therefore, the storage capacity of the capacitor 57 is determined from the power consumption of the main circuit 110 of the first load 210 and the power outage time predetermined as the maximum value of the momentary power outage of the commercial power supply 200. In other words, the storage capacity of the capacitor 57 does not need to be determined considering the power consumption of the second load 220.
[0048] The input voltage to the DC fixing lamp 75 decreases to zero at time t1, and becomes the voltage output from the PFC circuit 55 at time t2.
[0049] The lamp drive circuit 77 is a relay circuit that switches the DC fixing lamp 75 on and off based on the output of a thyristor, and does not have non-volatile memory or a CPU. Therefore, even if the voltage supplied to the lamp drive circuit 77 drops to zero, it can continue to control the DC fixing lamp 75 on and off after the voltage supply is restored.
[0050] Here, we will describe a comparative example circuit in which the diode 59 is removed from the internal circuit of the power supply unit 50 shown in Figure 3. Figure 5 is a diagram showing an example of the voltages in the comparative example circuit. In Figure 5, from top to bottom, the input voltage of the NF circuit 51, the input voltage of the DC / DC circuit 211, the output voltage of the DC / DC circuit 211, and the input voltage of the DC fixing lamp 75 are shown. Note that the input voltage of the DC fixing lamp 75 is the voltage when it is switched on by the lamp drive circuit 77.
[0051] This example illustrates a case where a momentary power outage occurs in the commercial power supply 200, where power is momentarily unavailable for 20ms between time t1 and time t2. The input voltage of the NF circuit 51 is affected during the momentary power outage, as power is not supplied from the commercial power supply 200.
[0052] When no AC power is input to the NF circuit 51 from the commercial power supply 200, the output voltage of the PFC circuit 55 decreases. As a result, the capacitor 57 begins to discharge, and a DC voltage is applied to the DC / DC circuit 211 and the lamp drive circuit 77. Therefore, as shown in the fourth row of Figure 5, the input voltage of the DC fixing lamp 75 gradually decreases from time t1, reaching its lowest value at time t2. After time t2, the input voltage of the DC fixing lamp 75 gradually increases to the voltage output from the PFC circuit 55. The reason why the input voltage of the DC fixing lamp 75 does not immediately become the voltage output from the PFC circuit 55 at time t2 is because the capacitor 57 stores energy.
[0053] On the other hand, as shown in the second row of Figure 5, the input voltage of the DC / DC circuit 211 gradually decreases and falls below the lower limit VT1 at time t3. Power supplied from capacitor 57 is supplied to the DC / DC circuit 211, but because power is consumed by the lamp drive circuit 77, the voltage falls below the lower limit VT1. At time t2, a constant voltage is supplied again from the PFC circuit 55, but since capacitor 57 starts to store energy, the voltage gradually increases and reaches the lower limit VT1 at time t4.
[0054] The input voltage to the DC / DC circuit 211 gradually decreases to zero from time t3, then gradually increases from time t2, reaching a voltage V1 at time t4 that is sufficient to drive the main circuit 110. Therefore, at time t3, the main circuit 110 is no longer supplied with the voltage V1 necessary to drive it. At time t3, the data stored in RAM 114 is erased, and the CPU 111 stops operating. Subsequently, at time t4, the CPU 111 restarts. Therefore, if a momentary power outage occurs, the CPU 111 restarts, making it impossible to continue the operation that was in place before the power outage.
[0055] <First variation> Figure 6 shows an example of the internal circuit configuration of the power supply in the first modified example. Referring to Figure 6, the differences between the power supply 50A in the first modified example and the power supply 50 described above are that the diode 59 has been removed, a switch 63 has been placed between the PFC circuit 55 and the second load 220, and a control unit 61 has been added. The other configurations of the power supply 50A in the first modified example are the same as those of the power supply 50 described above. Therefore, a detailed explanation of them will not be repeated.
[0056] The power supply unit 50A in the first modified example includes an NF circuit 51, a rectifier circuit 53, a PFC circuit 55, a capacitor 57, a switch 63, and a control unit 61.
[0057] The output of the PFC circuit 55 is connected to one end of the capacitor 57, the first load 210, and one end of the switch 63. The other end of the capacitor 57 is grounded. The other end of the switch 63 is connected to the second load 220. The capacitor 57, the first load 210, and the second load 220 are connected in parallel to the PFC circuit 55. One end of the switch 63 is connected between the PFC circuit 55 and one end of the capacitor 57. Alternatively, one end of the switch 63 may be connected between one end of the capacitor 57 and the first load 210.
[0058] The control unit 61 is a microcomputer and includes a CPU, ROM, and RAM. The control unit 61 is powered by the PFC circuit 55. The control unit 61 may also be equipped with a capacitor as a backup power source. Furthermore, the control unit 61 may be integrated into the PFC circuit 55.
[0059] The control unit 61 receives the output voltage of the PFC circuit 55 as input. The PFC circuit 55 has a detection unit that detects the output voltage and outputs the value of the output voltage detected by the detection unit. The control unit 61 controls the switch 63 based on the output voltage of the PFC circuit 55. The control unit 61 compares the value of the output voltage of the PFC circuit 55 with a predetermined threshold VT2. The control unit 61 closes the switch 63 while the value of the output voltage of the PFC circuit 55 is greater than the threshold VT2, and opens the switch 63 while the value of the output voltage of the PFC circuit 55 is less than or equal to the threshold VT2. Therefore, power is supplied to the second load 220 while the value of the output voltage of the PFC circuit 55 is greater than the threshold VT2. Power is not supplied to the second load 220 while the value of the output voltage of the PFC circuit 55 is less than or equal to the threshold VT2. The threshold VT2 is determined from the maximum power consumption of the first load 210. Preferably, the threshold VT2 is greater than or equal to the maximum power consumption of the first load 210.
[0060] Figure 7 shows an example of the voltages in the circuit during a momentary power outage in the first modified example. In Figure 7, from top to bottom, the input voltage of the NF circuit 51, the output voltage of the PFC circuit 55, the input voltage of the DC / DC circuit 211, the output voltage of the DC / DC circuit 211, and the input voltage of the DC fixing lamp 75 are shown. Note that the input voltage of the DC fixing lamp 75 is the voltage when it is switched on by the lamp drive circuit 77.
[0061] This example illustrates a momentary power outage in the commercial power supply 200, where power is momentarily unavailable for 20ms between time t1 and time t2. The input voltage of the NF circuit 51 represents the value during the momentary power outage when power is not supplied from the commercial power supply 200.
[0062] At time t1, no AC power is input to the NF circuit 51 from the commercial power supply 200, so the output voltage of the PFC circuit 55 drops to below the threshold VT2. Accordingly, the switch 63 opens at time t1, and the input voltage of the DC fixing lamp 75 becomes zero.
[0063] At time t2, when AC power is input to the NF circuit 51 from the commercial power supply 200, the output voltage of the PFC circuit 55 rises and becomes greater than the threshold VT2. Accordingly, the switch 63 closes at time t2, so the input voltage of the DC fixing lamp 75 becomes the voltage used during normal operation.
[0064] The lamp drive circuit 77 is a relay circuit that switches the DC fixing lamp 75 on and off based on the output of a thyristor, and does not have non-volatile memory or a CPU. Therefore, even after the voltage supplied to the lamp drive circuit 77 drops to zero, the on / off control of the DC fixing lamp 75 can continue after a predetermined voltage is supplied.
[0065] Referring to Figure 6, when AC power is not input to the NF circuit 51 from the commercial power supply 200, the output voltage of the PFC circuit 55 decreases. As a result, the capacitor 57 begins to discharge, and a DC voltage is applied to the DC / DC circuit 211. Therefore, as shown in the third row of Figure 7, the input voltage of the DC / DC circuit 211 gradually decreases, but remains above the lower limit value VT1. The output voltage of the DC / DC circuit 211 maintains a constant value V1 even during the momentary power outage. The power supplied from the capacitor 57 is not supplied to the lamp drive circuit 77 because the switch 63 is open. Therefore, the storage capacity of the capacitor 57 is determined from the power consumption of the main circuit 110 of the first load 210 and the power outage time predetermined as the maximum value of the momentary power outage of the commercial power supply 200. In other words, the storage capacity of the capacitor 57 does not need to be determined considering the power consumption of the second load 220.
[0066] <Second variation> Figure 8 shows an example of the internal circuit configuration of the power supply in the second modified example. Referring to Figure 8, the difference between the power supply 50B in the second modified example and the power supply 50 described above is that a lamp diode 69 and a lamp capacitor 67 are placed between the PFC circuit 55 and the second load 220. The other configurations of the power supply 50B in the second modified example are the same as those of the power supply 50 described above. Therefore, a detailed explanation of them will not be repeated.
[0067] The output of the PFC circuit 55 is connected to the anodes of diode 59 and lamp diode 69, respectively. The cathode of lamp diode 69 is connected to the first load 210. One end of lamp capacitor 67 is connected between the cathode of lamp diode 69 and the second load 220. The other end of lamp capacitor 67 is grounded. Capacitor 57, first load 210, lamp capacitor 67, and second load 220 are connected in parallel to the PFC circuit 55.
[0068] Figure 9 shows an example of the voltages in the circuit during a momentary power outage in the second modified example. In Figure 9, from top to bottom, the input voltage of the NF circuit 51, the input voltage of the DC / DC circuit 211, the output voltage of the DC / DC circuit 211, and the input voltage of the DC fixing lamp 75 are shown. Note that the input voltage of the DC fixing lamp 75 is the voltage when it is switched on by the lamp drive circuit 77.
[0069] Compared to Figure 4, the input voltage of the DC fixing lamp 75 shown in the fourth row of Figure 5 is different. Referring to Figures 8 and 9, at time t1, when AC power is no longer input to the NF circuit 51 from the commercial power supply 200, the output voltage of the PFC circuit 55 decreases. As a result, the lamp capacitor 67 starts to discharge, and a DC voltage is applied to the lamp drive circuit 77. Therefore, as shown in the fourth row of Figure 9, the input voltage of the DC fixing lamp 75 gradually decreases. The power supplied from the lamp capacitor 67 is interrupted by the lamp diode 69 and is not supplied to the DC / DC circuit 211.
[0070] At time t2, when AC power is input to the NF circuit 51 from the commercial power supply 200, the output voltage of the PFC circuit 55 rises. This causes the lamp capacitor 67 to start storing energy, and the DC voltage applied to the lamp drive circuit 77 also rises. As a result, as shown in the fourth row of Figure 9, the input voltage of the DC fixing lamp 75 gradually increases.
[0071] The storage capacity of the lamp capacitor 67 can be determined from the power consumption of the DC fixing lamp 75 and the maximum duration of the momentary power outage. It is preferable that the capacity of the lamp capacitor 67 be such that it can maintain power at or above the operating voltage of the lamp capacitor 67 during the momentary power outage. In this case, the DC fixing lamp 75 can be operated normally during the momentary power outage. Although the product cost increases because the lamp capacitor 67 is added, the capacity of the lamp capacitor 67 is smaller than the capacity of a single capacitor used to supply power to the first load 210 and the second load 220. Capacitors become more expensive as their storage capacity increases. Therefore, it may be possible to reduce the product cost.
[0072] As described above, the power supply device 50 in this embodiment includes an NF circuit 51 to which any of a plurality of commercial power supplies can be connected, a capacitor 57, a PFC circuit 55, and a diode 59 (switching unit) arranged between the first load 210 and the capacitor 57 and the PFC circuit 55. The capacitor 57, the first load 210 and the second load 220 are connected in parallel to the PFC circuit 55. The PFC circuit 55 converts the AC input to the NF circuit 51 into DC of a predetermined voltage and outputs it to the capacitor 57, the first load 210 and the second load 220.
[0073] The first load 210, the second load 220, and the capacitor 57 are connected in parallel to the PFC circuit 55, so that power is supplied to the first load 210, the second load 220, and the capacitor 57 while power is being output from the PFC circuit 55. Furthermore, during a momentary power outage of the commercial power supply 200, the diode 59 switches the system to a state where power is not supplied from the capacitor 57 to the second load 220 and power is supplied to the first load 210. Therefore, since power is not supplied from the capacitor 57 to the second load 220, the energy storage capacity of the capacitor 57 can be reduced, thereby suppressing manufacturing costs.
[0074] The power supply unit 50A in the first modified example includes an NF circuit 51 to which any of a plurality of commercial power supplies can be connected, a capacitor 57, a PFC circuit 55, a switch 63 (switching unit) positioned between the PFC circuit 55 and the second load 220, and a control unit 61 that controls the switch 63 based on whether or not there is a momentary power outage of the commercial power supply 200. The capacitor 57, the first load 210 and the second load 220 are connected in parallel to the PFC circuit 55. The PFC circuit 55 converts the AC input to the NF circuit 51 into DC of a predetermined voltage and outputs it to the capacitor 57, the first load 210 and the second load 220.
[0075] A switch 63 is placed between the PFC circuit 55 and the second load 220, and the control unit 61 controls the switch 63 based on whether or not there is a momentary power outage in the commercial power supply 200. Therefore, by controlling the switch 63 to open during a momentary power outage in the commercial power supply 200, power can be supplied from the capacitor 57 to the first load 210, while preventing power from being shared between the capacitor 57 and the second load 220.
[0076] Furthermore, the PFC circuit 55 includes a detection unit that detects its output voltage, and the control unit 61 compares the voltage value detected by the detection unit with a threshold value VT2. The threshold value VT2 is determined from the maximum power consumption of the first load 210. This ensures that the power required by the first load 210 is supplied to the commercial power supply 200 during a momentary power outage.
[0077] Furthermore, the MFP100 is further equipped with a DC / DC circuit 211 that converts the DC voltage output from the PFC circuit 55. The DC / DC circuit 211 may be provided by the MFP100 or by the power supply unit 50. Therefore, even if the first load 210 is equipped with multiple loads that are driven by multiple voltages, power can be supplied to each of the multiple loads.
[0078] Furthermore, the first load 210 is the main circuit 110 equipped with a CPU 111 and RAM 114. The second load 220 does not include volatile memory or a central processing unit. Therefore, the power supply 50 can prevent the CPU 111 of the first load 210 from stopping during a momentary power outage. Since the second load 220 does not include volatile memory or a central processing unit, its operation is not affected even if there is a momentary power outage.
[0079] The storage capacity of capacitor 57 is determined by the power consumption of the first load 210 and a predetermined blackout period during which the commercial power supply 200 experiences a momentary power outage. Therefore, power can be supplied to the first load 210 from capacitor 57 for at least the duration of the blackout.
[0080] <Summary of Embodiments> (Item 1) An AC input section to which any of several commercial power sources can be connected, The energy storage unit, A power factor correction circuit converts the AC input to the AC input unit into DC of a predetermined voltage and outputs it to the parallel-connected energy storage unit, an external first load, and a second load. A power supply device comprising: a switching unit that switches to a state in which power is supplied from the energy storage unit to the first load and power is not supplied from the energy storage unit to the second load while the commercial power supply connected to the AC input unit is momentarily interrupted.
[0081] In this configuration, the first load, the second load, and the energy storage unit are connected in parallel to the power factor correction circuit. As long as power is output from the power factor correction circuit, power is supplied to the first load, the second load, and the energy storage unit. Furthermore, during a momentary power outage of the commercial power supply, the system switches to a state where power is not supplied from the energy storage unit to the second load, but power is supplied to the first load. Therefore, during the period of a momentary power outage of the commercial power supply, power is supplied from the energy storage unit to the first load, but not to the second load. Consequently, since power is not supplied from the energy storage unit to the second load, the energy storage capacity can be reduced. As a result, a power supply device with reduced manufacturing costs can be provided.
[0082] (Item 2) The switching unit includes a diode disposed between the first load and the energy storage unit and the power factor correction circuit, The second load is connected between the power factor correction circuit and the diode, as described in item 1.
[0083] In this configuration, a diode is placed between the first load and the energy storage unit and the power factor correction circuit, and the second load is connected between the power factor correction circuit and the diode. Therefore, while the power factor correction circuit is not outputting power, power is supplied from the energy storage unit to the first load, and power is not shared between the energy storage unit and the second load.
[0084] (Item 3) The switching unit includes a switch positioned between the power factor correction circuit and the second load, The power supply device according to item 1, further comprising a control unit that controls the switch based on whether or not there is an instantaneous power outage in the commercial power supply.
[0085] In this scenario, a switch is placed between the power factor correction circuit and the second load, and the switch is controlled based on whether or not there is a momentary power outage in the commercial power supply.
[0086] In this scenario, by controlling the switch to open during a momentary power outage in the commercial power supply, power can be supplied from the energy storage unit to the first load, while preventing power from being shared between the energy storage unit and the second load.
[0087] (Item 4) Further comprising a detection unit for detecting the DC voltage value output from the power factor correction circuit, The power supply device according to item 3, wherein the control unit compares the voltage value detected by the detection unit with a threshold value determined from the maximum power consumption of the first load.
[0088] In this scenario, the threshold value used to compare the DC voltage output from the power factor correction circuit is determined by the maximum power consumption of the first load. This ensures that the power required by the first load is supplied to the first load even during a momentary power outage of the commercial power supply.
[0089] (Item 5) A power supply device according to any one of Items 1 to 4, further comprising a transformer circuit for converting the DC voltage output from the power factor correction circuit.
[0090] Following this approach, since it includes a transformer circuit, it can supply power to multiple loads, each driven by a different voltage.
[0091] (Item 6) The first load includes volatile memory and a central processing unit, The second load is a power supply according to any one of items 1 to 5, which does not include volatile memory and a central processing unit.
[0092] In this scenario, the first load includes volatile memory and the central processing unit (CDA), so the CDA can be kept from shutting down. The second load does not include volatile memory or the CDA, so it can operate without disruption even if there is a momentary power outage.
[0093] (Item 7) The power supply device according to any one of Items 1 to 6, wherein the storage capacity of the energy storage unit is determined from the power consumption of the first load and a predetermined power outage time which is the time when AC is not output from the AC input unit.
[0094] Following this procedure, power can be supplied to the first load from the energy storage unit for at least the duration of the power outage.
[0095] (Item 8) An image processing apparatus comprising a power supply unit according to any one of items 1 to 7, the first load and the second load.
[0096] Following this approach, it is possible to provide an image processing apparatus with reduced manufacturing costs. The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]
[0097] 50, 50A, 50B Power supply unit, 100 MFP, 51 NF circuit, 53 Rectifier circuit, 54 Heat source, 55 PFC circuit, 57 Capacitor, 59 Diode, 61 Control unit, 63 Switch, 67 Lamp capacitor, 69 Lamp diode, 70 Fixing unit, 71 Pressure roller, 73 Heating roller, 75 DC fixing lamp, 77 Lamp drive circuit, 102 RAM, 110 Main circuit, 111 CPU, 112 Communication I / F unit, 113 ROM, 114 RAM, 115 HDD, 116 Facsimile unit, 120 Automatic document transport unit, 130 Document reading unit, 140 Image forming unit, 150 Paper feeding unit, 160 Operation panel, 163 Operation unit, 170 External storage device, 171 CD-ROM, 200 Commercial power supply, 210 First load, 211 DC / DC circuit, 220 second load, V1 voltage, VT1 lower limit, VT2 threshold.
Claims
1. An AC input section to which any of multiple commercial power sources can be connected, The energy storage unit, A power factor correction circuit converts the AC input to the AC input unit into DC of a predetermined voltage and outputs it to the parallel-connected energy storage unit, an external first load, and a second load. A power supply device comprising: a switching unit that switches to a state in which power is supplied from the energy storage unit to the first load and power is not supplied from the energy storage unit to the second load while the commercial power supply connected to the AC input unit is momentarily interrupted.
2. The switching unit includes a diode disposed between the first load and the energy storage unit and the power factor correction circuit. The power supply device according to claim 1, wherein the second load is connected between the power factor correction circuit and the diode.
3. The switching unit includes a switch positioned between the power factor correction circuit and the second load, The power supply device according to claim 1, further comprising a control unit that controls the switch based on whether or not there is an instantaneous power outage in the commercial power supply.
4. The system further includes a detection unit for detecting the DC voltage value output from the power factor correction circuit, The power supply device according to claim 3, wherein the control unit compares the voltage value detected by the detection unit with a threshold value determined from the maximum power consumption of the first load.
5. The power supply device according to any one of claims 1 to 4, further comprising a transformer circuit for converting the DC voltage output from the power factor correction circuit.
6. The first load includes a volatile memory and a central processing unit. The power supply device according to any one of claims 1 to 4, wherein the second load does not include volatile memory and a central processing unit.
7. The power supply device according to any one of claims 1 to 4, wherein the storage capacity of the storage unit is determined from the power consumption of the first load and a predetermined power outage time, which is the time when AC is no longer output from the AC input unit.
8. An image processing apparatus comprising a power supply device according to any one of claims 1 to 4, the first load and the second load.