Electronic apparatus, and voltage control method

Abstract

To provide an electronic apparatus capable of suppressing occurrence of ringing, and a voltage control method.SOLUTION: An image forming apparatus comprises: a resistor 71 and a capacitor 72 connected in parallel between a specific section 42A, which is between a switch 43 and an inrush current suppression circuit 44 in a power supply path 42, and a ground; and a control unit 7 which detects a voltage in the specific section 42A in a detection cycle, determines whether or not the time of a transition from an OFF state to an ON state of the switch 43 elapses; determines, each time a voltage is detected from the time of the transition, a magnitude relation between the detected voltage and a target range corresponding to the number of times of voltage detection from the time of the transition, and controls conduction / interruption of a first electrification path 81 and a second electrification path 82 in accordance with a result of the determination.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electronic device and a voltage control method. [Background technology]

[0002] An electronic device is known that includes an inrush current suppression circuit that suppresses an inrush current that flows in response to a transition from an off state to an on state of a switch provided in a power supply path between a power source and a load. The inrush current suppression circuit includes a switching element provided in the power supply path between the switch and the load.

[0003] In the electronic device equipped with the inrush current suppression circuit, ringing, in which the voltage of the power supply line fluctuates, may occur for a while after the switch transitions from an off state to an on state due to parasitic capacitance of the switching element. In response to this, a technique is known for suppressing the occurrence of ringing by using a snubber circuit (see, for example, Patent Document 1) including a resistor and a capacitor connected in series between the power supply line and ground. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-111398 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since the parasitic capacitance of the switching element varies depending on the individual element, the snubber circuit with a fixed RC constant may not be able to suppress the occurrence of ringing.

[0006] An object of the present invention is to provide an electronic device and a voltage control method that can suppress the occurrence of ringing. [Means for solving the problem]

[0007] According to one aspect of the present invention, an electronic device includes a switch, an inrush current suppression circuit, a resistor and a capacitor, a detection processor, a first determination processor, a second determination processor, and a current control unit. The switch switches between conduction and interruption of a power supply path between a power source and a load. The inrush current suppression circuit includes a switching element disposed between the switch and the load in the power supply path, and suppresses an inrush current that flows in response to a transition of the switch from an off state to an on state. The resistor and the capacitor are connected in parallel between a specific section of the power supply path between the switch and the inrush current suppression circuit and ground. The detection processor detects a voltage in the specific section at a predetermined detection interval. The first determination processor determines whether a transition time from an off state to an on state of the switch has elapsed based on a change in the voltage detected by the detection processor. The second determination processor determines, each time the detection processor detects the voltage since the transition of the switch from an off state to an on state, whether the detected voltage is higher or lower than a target range corresponding to the number of times the voltage has been detected since the transition. When the detected voltage is determined to be higher than the target range, the current control unit conducts a first current path from the specific section via the resistor to the ground and a second current path from the specific section via the capacitor to the ground; when the detected voltage is determined to be within the target range, the current control unit cuts off the first current path and conducts the second current path; and when the detected voltage is determined to be lower than the target range, the current control unit cuts off the first current path and the second current path.

[0008] A voltage control method according to another aspect of the present invention is executed by an electronic device including a switch that switches between conduction and interruption of a power supply path between a power source and a load, an inrush current suppression circuit including a switching element provided in the power supply path between the switch and the load and that suppresses an inrush current that flows in response to a transition of the switch from an off state to an on state, and a resistor and a capacitor connected in parallel between a specific section of the power supply path between the switch and the inrush current suppression circuit and ground, and the voltage control method includes a detection step, a first determination step, a second determination step, and a current control step. In the detection step, a voltage in the specific section is detected at a predetermined detection cycle. In the first determination step, it is determined whether a transition time from an off state to an on state of the switch has elapsed based on a change in the voltage detected in the detection step. In the second determination step, each time the voltage is detected in the detection step since the transition of the switch from an off state to an on state, a relationship between the detected voltage and a target range corresponding to the number of times the voltage has been detected since the transition is determined. In the current control step, if it is determined that the detected voltage is higher than the target range, a first current path from the specific section via the resistor to the ground and a second current path from the specific section via the capacitor to the ground are made conductive; if it is determined that the detected voltage is within the target range, the first current path is cut off and the second current path is made conductive; and if it is determined that the detected voltage is lower than the target range, the first current path and the second current path are cut off. [Effects of the Invention]

[0009] According to the present invention, it is possible to suppress the occurrence of ringing. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2]FIG. 2 is a block diagram showing the system configuration of the image forming apparatus according to the embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing the configuration of a power supply unit of the image forming apparatus according to the embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing an example of a transition of voltage in a specific section of the image forming apparatus according to the embodiment of the present invention. [Figure 5] FIG. 5 is a diagram showing an example of target values corresponding to the number of times of voltage detection used in the image forming apparatus according to the embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing an example of a voltage transition in a specific section of the image forming apparatus according to the embodiment of the present invention. [Figure 7] FIG. 7 is a flowchart showing an example of a voltage control process executed in the image forming apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following embodiment is an example of a specific embodiment of the present invention and does not limit the technical scope of the present invention.

[0012] [Configuration of image forming apparatus 100] First, the configuration of an image forming apparatus 100 according to an embodiment of the present invention will be described with reference to Figures 1 to 3. In Figure 3, an inrush current suppression circuit 44 is indicated by a dashed line. Also in Figure 3, control signals SG11 and SG12 output from the control unit 7 are indicated by dashed lines with arrows.

[0013] The image forming apparatus 100 is a multifunction peripheral having multiple functions, such as a scanning function for reading an image from a document, a printing function for forming an image based on image data, a fax function, and a copy function. The image forming apparatus 100 is an example of an electronic device of the present invention. The electronic device of the present invention may be an image forming apparatus such as a printer, a fax machine, or a copy machine. Furthermore, the electronic device of the present invention is not limited to an image forming apparatus.

[0014] 1 and 2, the image forming apparatus 100 includes an ADF (Auto Document Feeder) 1, an image reading unit 2, an image forming unit 3, a sheet conveying unit 4, an operation display unit 5, a storage unit 6, and a control unit 7. The image forming apparatus 100 also includes a power supply unit 8 shown in FIG.

[0015] The ADF 1 transports documents to be scanned by the scanning function, and includes a document setting section, a plurality of transport rollers, a document holder, and a paper ejection section.

[0016] The image reading unit 2 realizes the scanning function and includes a document table, a light source, a plurality of mirrors, an optical lens, and a CCD (Charge Coupled Device).

[0017] The image forming unit 3 realizes the printing function. As shown in Fig. 1, the image forming unit 3 includes a photosensitive drum 11, a charging roller 12, an optical scanning device 13, a developing device 14, a toner container 15, a transfer roller 16, a cleaning device 17, a fixing device 18, and a paper output tray 19.

[0018] Photosensitive drum 11 is provided so as to be rotatable in the direction of the arrow shown in Fig. 1. Charging roller 12 is provided in contact with the circumferential surface of photosensitive drum 11 and charges the circumferential surface of photosensitive drum 11. Optical scanning device 13 irradiates the circumferential surface of photosensitive drum 11, which has been charged by charging roller 12, with light based on image data. An electrostatic latent image is formed on the circumferential surface of photosensitive drum 11 by optical scanning device 13.

[0019] The developing device 14 uses toner to develop the electrostatic latent image formed on the circumferential surface of the photosensitive drum 11. The toner container 15 supplies toner to the developing device 14. The transfer roller 16 transfers the electrostatic latent image (toner image) developed by the developing device 14 onto a sheet transported by the sheet transport unit 4. The cleaning device 17 cleans the circumferential surface of the photosensitive drum 11 after the toner image has been transferred by the transfer roller 16.

[0020] The fixing device 18 fixes the toner image transferred onto the sheet by the transfer roller 16. The sheet onto which the toner image has been fixed by the fixing device 18 is discharged to a paper discharge tray 19.

[0021] The sheet conveying unit 4 conveys a sheet on which an image is formed by the image forming unit 3. As shown in FIG. 1 , the sheet conveying unit 4 includes a paper feed cassette 21, a pickup roller 22, a paper feed roller 23, a plurality of first conveying rollers 24, and a plurality of second conveying rollers 25.

[0022] The paper feed cassette 21 is detachably provided in the housing of the image forming apparatus 100, and holds sheets to be supplied to the image forming unit 3. The pickup roller 22 picks up the top sheet from the paper feed cassette 21 among the multiple sheets stacked in the paper feed cassette 21.

[0023] The paper feed roller 23 transports the sheet picked up from the paper feed cassette 21 by the pickup roller 22 to a sheet transport path that leads to a position where the toner image is transferred by the transfer roller 16, via the fixing device 18, and to the paper output tray 19. A plurality of first transport rollers 24 are provided on the sheet transport path upstream of the fixing device 18 in the sheet transport direction, and transport the sheet to the fixing device 18 via the position where the toner image is transferred by the transfer roller 16. A plurality of second transport rollers 25 are provided on the sheet transport path downstream of the fixing device 18 in the sheet transport direction, and transport the sheet to the paper output tray 19.

[0024] The operation display unit 5 is a user interface of the image forming apparatus 100. The operation display unit 5 has a display unit such as a liquid crystal display that displays various information in response to control instructions from the control unit 7, and an operation unit such as operation keys or a touch panel that inputs various information to the control unit 7 in response to user operations.

[0025] The storage unit 6 is a nonvolatile storage device. For example, the storage unit 6 is a nonvolatile memory such as a flash memory. The storage unit 6 may be an SSD (Solid State Drive) or an HDD (Hard Disk Drive).

[0026] The control unit 7 performs overall control of the image forming apparatus 100. As shown in FIG. 2, the control unit 7 includes a CPU 31, a ROM 32, and a RAM 33. The CPU 31 is a processor that executes various types of arithmetic processing. The ROM 32 is a non-volatile storage device that stores in advance information such as control programs for causing the CPU 31 to execute various types of processing. The RAM 33 is a volatile or non-volatile storage device that is used as a temporary storage memory (work area) for the various types of processing executed by the CPU 31. The CPU 31 performs overall control of the image forming apparatus 100 by executing the various control programs that are stored in advance in the ROM 32.

[0027] The control unit 7 may be a control unit provided separately from a main control unit that performs overall control of the image forming apparatus 100. The control unit 7 may also be configured with an electronic circuit such as an integrated circuit (ASIC).

[0028] The power supply unit 8 supplies power to a load 40 (see FIG. 3).

[0029] For example, the load 40 is a motor that generates a rotational driving force to rotate the photosensitive drum 11. The load 40 may also be a motor that generates a rotational driving force to rotate the pressure roller, the pickup roller 22, the paper feed roller 23, the plurality of first transport rollers 24, or the plurality of second transport rollers 25 included in the fixing device 18. The load 40 may also include a plurality of motors. The load 40 is not limited to a motor and may also be a solenoid, an electromagnetic clutch, a heater, or the like.

[0030] As shown in FIG. 3, the power supply unit 8 includes a power supply 41, a power supply line 42, a switch 43, an inrush current suppression circuit 44, a voltage dividing circuit 45, and a snubber control circuit 46.

[0031] Power supply 41 outputs power in response to power supply from an external commercial power supply (not shown). Specifically, power supply 41 is an AC-DC converter that converts AC voltage output from the commercial power supply into DC voltage of a predetermined voltage value and outputs the DC voltage. Note that power supply 41 may also be a DC-DC converter.

[0032] The power supply line 42 is a current path that connects the power source 41 and the load 40 .

[0033] The switch 43 switches between conduction and interruption of the power supply path 42. For example, the switch 43 is an interlock switch that switches on and off in conjunction with the opening and closing of an exterior cover (not shown) of the image forming apparatus 100.

[0034] The inrush current suppression circuit 44 suppresses an inrush current that flows in response to the transition of the switch 43 from an off state to an on state. As shown in FIG. 3 , the inrush current suppression circuit 44 includes a field effect transistor (FET) 51, a capacitor 52, a resistor 53, and a resistor 54.

[0035] The FET 51 is a P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor). As shown in FIG. 3, the source terminal of the FET 51 is connected to the switch 43. The source terminal of the FET 51 is also connected to the gate terminal of the FET 51 via a capacitor 52. The source terminal of the FET 51 is also connected to the gate terminal of the FET 51 via a resistor 53. The gate terminal of the FET 51 is connected to ground via a resistor 54. The drain terminal of the FET 51 is connected to the load 40.

[0036] 3, the FET 51 is provided between the switch 43 and the load 40 in the power supply line 42. The FET 51 is an example of the switching element of the present invention.

[0037] In the image forming apparatus 100, due to the parasitic capacitance of the FET 51, ringing (see FIG. 4) may occur, in which the voltage of the power supply line 42 fluctuates for a while after the switch 43 transitions from the off state to the on state. In FIG. 4, the transition of the voltage of the power supply line 42 is indicated by a bold line. In response to this, a technique is known for suppressing the occurrence of ringing by using a snubber circuit including a resistor and a capacitor connected in series between the power supply line 42 and ground.

[0038] However, since the parasitic capacitance of the FET 51 varies depending on the individual FET, the snubber circuit with a fixed RC constant may not be able to suppress the occurrence of ringing.

[0039] In contrast to this, in the image forming apparatus 100 according to the embodiment of the present invention, it is possible to suppress the occurrence of ringing, as will be described below.

[0040] The voltage dividing circuit 45 divides the voltage V0 (see FIG. 4) of the power supply 41 into a voltage that can be input to the control unit 7 and outputs the voltage to the control unit 7. The voltage dividing circuit 45 includes voltage dividing resistors 61 and 62 that are connected in series between a specific section 42A (see FIG. 3) between the switch 43 and the inrush current suppression circuit 44 in the power supply line 42 and the ground.

[0041] The snubber control circuit 46 includes a resistor 71, a capacitor 72, a conduction interruption switching unit 73, and a conduction interruption switching unit 74 shown in FIG.

[0042] As shown in FIG. 3, a resistor 71 and a capacitor 72 are connected in parallel between a specific section 42A (see FIG. 3) of the power supply line 42 and the ground.

[0043] The conduction interruption switching unit 73 switches between conduction and interruption of a first electric path 81 (see FIG. 3) that runs from the specific section 42A to ground via the resistor 71 in response to an input of a control signal SG11 (see FIG. 3) output from the control unit 7. The control signal SG11 is a high-level digital signal. For example, the conduction interruption switching unit 73 makes the first electric path 81 conductive while the control signal SG11 is being input. Furthermore, the conduction interruption switching unit 73 interrupts the first electric path 81 in response to the cessation of the input of the control signal SG11. Specifically, the conduction interruption switching unit 73 is an electronic circuit that includes a switching element such as a transistor.

[0044] The conduction interruption switching unit 74 switches between conduction and interruption of a second current path 82 (see FIG. 3) that runs from the specific section 42A to ground via the capacitor 72 in response to an input of a control signal SG12 (see FIG. 3) output from the control unit 7. The control signal SG12 is a high-level digital signal. For example, the conduction interruption switching unit 74 makes the second current path 82 conductive while the control signal SG12 is being input. Furthermore, the conduction interruption switching unit 74 interrupts the second current path 82 in response to the cessation of input of the control signal SG12. Specifically, the conduction interruption switching unit 74 is an electronic circuit that includes a switching element such as a transistor.

[0045] [Configuration of control unit 7] Next, the configuration of the control unit 7 will be described in more detail with reference to FIG.

[0046] As shown in FIG. 2, the control unit 7 includes a detection processing unit 91, a first determination processing unit 92, a second determination processing unit 93, and an energization control unit 94.

[0047] Specifically, a voltage control program for causing the CPU 31 to function as each of the above-mentioned functional units is stored in advance in the ROM 32 of the control unit 7. The CPU 31 executes the voltage control program stored in the ROM 32 to function as each of the above-mentioned functional units.

[0048] The voltage control program may be recorded on a computer-readable recording medium such as a CD, DVD, or flash memory, and may be read from the recording medium and stored in a storage device such as the memory unit 6. Some or all of the functional units included in the control unit 7 may be configured with electronic circuits. The voltage control program may also be a program for causing multiple processors to function as the functional units included in the control unit 7.

[0049] The detection processing unit 91 detects the voltage in the specific section 42A (see FIG. 3) at a predetermined detection cycle.

[0050] Specifically, the detection processing unit 91 detects the voltage in the specific section 42A based on the divided voltage input from the voltage dividing circuit 45.

[0051] Here, the detection period is set to be shorter than the reciprocal of the frequency of the ringing (see FIG. 4). The horizontal axis of the graph shown in FIG. 4 indicates detection timings t1 to t24 of the voltage arriving in the detection period.

[0052] Based on the change in voltage detected by the detection processing unit 91, the first determination processing unit 92 determines whether or not the time for the switch 43 to transition from the off state to the on state has passed.

[0053] Specifically, the first determination processing unit 92 determines that the transition time has passed when the voltage detected by the detection processing unit 91 increases beyond a predetermined reference amount.

[0054] Each time the detection processing unit 91 detects a voltage from the time the switch 43 transitions from the off state to the on state, the second judgment processing unit 93 determines whether the detected voltage is high or low relative to a target range corresponding to the number of times the voltage has been detected since the transition.

[0055] Here, the target range is a range that includes a target value corresponding to the number of times that the detection processing unit 91 detects the voltage. The target value is set so as to gradually approach the voltage V0 of the power supply 41 as the number of times that the detection processing unit 91 detects the voltage increases. In other words, the target value is set for each timing at which the detection processing unit 91 detects the voltage after the switch 43 transitions from the off state to the on state.

[0056] 5 shows an example of setting the target values corresponding to the number of times voltage is detected by the detection processing unit 91 in the image forming apparatus 100. The horizontal axis of the graph shown in Fig. 5 indicates the number of times (1 to 15) voltage is detected by the detection processing unit 91. In Fig. 5, target values X1 to X15 corresponding to the number of times (1 to 15) voltage is detected by the detection processing unit 91 are indicated by black circles.

[0057] 5, in the image forming apparatus 100, the target value is set so that the increase from the immediately preceding target value decreases as the number of times the voltage is detected by the detection processing unit 91 increases. Note that the target value may also be set so that it increases linearly as the number of times the voltage is detected by the detection processing unit 91 increases.

[0058] For example, the target range is a range centered around the target value, and the difference between the lower limit value and the upper limit value is a predetermined value.

[0059] If the detected voltage is determined to be higher than the target range, the current control unit 94 causes the first current path 81 (see Figure 3) and the second current path 82 (see Figure 3) to be conductive; if the detected voltage is determined to be within the target range, the current control unit 94 causes the first current path 81 to be interrupted and the second current path 82 to be conductive; and if the detected voltage is determined to be lower than the target range, the current control unit 94 causes the first current path 81 and the second current path 82 to be interrupted.

[0060] Specifically, when it is determined that the detected voltage is higher than the target range, the current control unit 94 outputs the control signals SG11 and SG12, which causes a portion of the inrush current to flow through the first current path 81 and the second current path 82. This significantly suppresses the rise in voltage in the specific section 42A.

[0061] Furthermore, when it is determined that the detected voltage is within the target range, the energization control unit 94 outputs the control signal SG12 and does not output the control signal SG11, which causes a portion of the inrush current to flow through the second current path 82. This suppresses the rise in voltage in the specific section 42A.

[0062] Furthermore, when it is determined that the detected voltage is lower than the target range, the energization control unit 94 does not output the control signal SG11 or the control signal SG12.

[0063] The current control unit 94 controls the conduction interruption of the first current path 81 and the second current path 82 based on the result of determining the high / low relationship between the detected voltage and the target range for each detection period. As a result, as shown in Fig. 6, it is possible to control the voltage in the specific section 42A so that it follows the transition line of the target value shown in Fig. 5. In Fig. 6, the transition of the voltage in the specific section 42A is indicated by a thick line. Also in Fig. 6, the transition of the voltage in the specific section 42A (the ringing) when control by the current control unit 94 is not executed is indicated by a two-dot chain line.

[0064] [Voltage control processing] 7, the voltage control method of the present invention will be described below along with an example of the voltage control process steps executed by the control unit 7 in the image forming apparatus 100. Here, steps S11, S12, etc. represent the numbers of the process steps executed by the control unit 7.

[0065] <Step S11> First, in step S11, the control unit 7 determines whether or not the timing for detecting the voltage in the specific section 42A has arrived.

[0066] Here, when the control unit 7 determines that the detection timing has arrived (Yes in S11), it shifts the process to step S12. On the other hand, when the detection timing has not arrived (No in S11), the control unit 7 waits for the arrival of the detection timing in step S11.

[0067] <Step S12> In step S12, the control unit 7 detects the voltage in the specific section 42 A. The process of step S12 is an example of a detection step of the present invention, and is executed by the detection processing unit 91 of the control unit 7.

[0068] <Step S13> In step S13, the control unit 7 determines whether the transition time from the OFF state to the ON state of the switch 43 has elapsed based on the change in voltage detected in the processing of step S12. The processing of step S13 is an example of a first determination step of the present invention, and is executed by the first determination processing unit 92 of the control unit 7.

[0069] Here, if the control unit 7 determines that the transition time has passed (Yes in S13), it shifts the process to step S14. On the other hand, if the transition time has not passed (No in S13), the control unit 7 shifts the process to step S11.

[0070] <Step S14> In step S14, the control unit 7 determines whether or not the detection result of the voltage in the most recent specific section 42A is higher than the target range corresponding to the number of times the voltage has been detected since the transition.

[0071] For example, if the number of times the voltage has been detected since the transition is one, the control unit 7 determines whether the voltage detection result for the most recent specific section 42A is higher than the target range including the target value X1 (see FIG. 5).

[0072] Here, if the control unit 7 determines that the voltage detection result for the most recent specific section 42A is higher than the target range corresponding to the number of times voltage has been detected since the transition (Yes in S14), it shifts the process to step S16. On the other hand, if the voltage detection result for the most recent specific section 42A is not higher than the target range corresponding to the number of times voltage has been detected since the transition (No in S14), it shifts the process to step S15.

[0073] <Step S15> In step S15, the control unit 7 determines whether the voltage detection result for the most recent specific section 42A is within the target range corresponding to the number of times the voltage has been detected since the transition. The processes of steps S14 and S15 are an example of a second determination step of the present invention, and are executed by the second determination processing unit 93 of the control unit 7.

[0074] Here, when the control unit 7 determines that the voltage detection result for the most recent specific section 42A is within the target range corresponding to the number of times voltage has been detected since the transition (Yes in S15), it shifts the process to step S17. On the other hand, when the voltage detection result for the most recent specific section 42A is not within the target range corresponding to the number of times voltage has been detected since the transition (No in S15), the control unit 7 shifts the process to step S18.

[0075] <Step S16> In step S16, the control unit 7 executes a first current control process for making the first current path 81 and the second current path 82 conductive.

[0076] <Step S17> In step S17, the control unit 7 executes a second current control process to interrupt the first current path 81 and make the second current path 82 conductive.

[0077] <Step S18> In step S18, the control unit 7 executes a third current control process to interrupt the first current path 81 and the second current path 82. The processes of steps S16, S17, and S18 are an example of a current control step of the present invention, and are executed by the current control unit 94 of the control unit 7.

[0078] <Step S19> In step S19, the control unit 7 determines whether or not the detection timing has arrived.

[0079] Here, when the control unit 7 determines that the detection timing has arrived (Yes in S19), it shifts the process to step S20. On the other hand, when the detection timing has not arrived (No in S19), the control unit 7 waits for the arrival of the detection timing in step S19.

[0080] <Step S20> In step S20, the control unit 7 detects the voltage in the specific section 42 A. The process of step S20 is an example of a detection step of the present invention, and is executed by the detection processing unit 91 of the control unit 7.

[0081] <Step S21> In step S21, the control unit 7 determines whether or not a predetermined termination condition is met.

[0082] Specifically, the termination condition is that the number of times the voltage in the specific section 42A has been detected since the transition time has elapsed has reached a predetermined number. Alternatively, the termination condition may be that the amount of change in the voltage in the specific section 42A falls below a predetermined amount.

[0083] Here, if the control unit 7 determines that the termination condition is satisfied (Yes in S21), it shifts the process to step S11. On the other hand, if the termination condition is not satisfied (No in S21), it shifts the process to step S14.

[0084] In this way, in image forming apparatus 100, after the transition time has elapsed, the conduction interruption of first current path 81 and second current path 82 is controlled based on the determination result of the high / low relationship between the detected voltage and the target range for each detection cycle. This makes it possible to control the voltage of specific section 42A based on the target range corresponding to each detection cycle that arrives after the transition time has elapsed. In other words, by appropriately setting the target range corresponding to each detection cycle that arrives after the transition time has elapsed, it is possible to suppress the occurrence of ringing.

[0085] [Notes on the Invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0086] <Appendix 1> a switch for switching between conduction and interruption of a power supply path between a power source and a load; an inrush current suppression circuit including a switching element provided between the switch and the load in the power supply path and suppressing an inrush current that flows in response to a transition of the switch from an off state to an on state; a resistor and a capacitor connected in parallel between a specific section in the power supply path between the switch and the inrush current suppression circuit and ground; a detection processing section for detecting a voltage in the specific section at a predetermined detection period; a first determination processing section for determining whether a transition time from an off state to an on state of the switch has passed based on a change in the voltage detected by the detection processing section; a second determination processing unit that, each time the voltage is detected by the detection processing unit, determines whether the detected voltage is higher or lower than a target range corresponding to the number of times the voltage has been detected since the transition; and a current control unit that, when it is determined that the detected voltage is higher than the target range, turns on a first current path from the specific section to the ground via the resistor and a second current path from the specific section to the ground via the capacitor, when it is determined that the detected voltage is included in the target range, cuts off the first current path and makes the second current path conductive, and when it is determined that the detected voltage is lower than the target range, cuts off the first current path and the second current path.

[0087] <Appendix 2> The electronic device described in Appendix 1, wherein the target range is a range that includes a target value corresponding to the number of times the voltage is detected by the detection processing unit, and the target value is set to gradually approach the voltage of the power supply as the number of times the voltage is detected by the detection processing unit increases.

[0088] <Appendix 3> 3. The electronic device according to claim 1, further comprising: an image reading unit that reads an image of a document; and an image forming unit that forms an image based on image data, or both of these.

[0089] <Appendix 4> a switch for switching between conduction and interruption of a power supply path between a power source and a load; an inrush current suppression circuit including a switching element provided between the switch and the load in the power supply path and suppressing an inrush current that flows in response to a transition of the switch from an off state to an on state; and a resistor and a capacitor connected in parallel between a specific section in the power supply path between the switch and the inrush current suppression circuit and ground, the voltage control method being executed by an electronic device comprising: a detection step of detecting a voltage in the specific section at a predetermined detection period; a first determination step of determining whether a transition time from an off state to an on state of the switch has elapsed based on a change in the voltage detected in the detection step; a second determination step of determining, each time the voltage is detected by the detection step from the time of the transition to the on state, whether the detected voltage is high or low relative to a target range corresponding to the number of times the voltage has been detected since the transition to the on state; and a current control step of, when it is determined that the detected voltage is higher than the target range, conducting a first current path from the specific section to the ground via the resistor and a second current path from the specific section to the ground via the capacitor, when it is determined that the detected voltage is included in the target range, interrupting the first current path and making the second current path conductive, and when it is determined that the detected voltage is lower than the target range, interrupting the first current path and the second current path. [Explanation of symbols]

[0090] 1 ADF 2 Image reading unit 3 Image forming unit 4 Sheet transport section 5 Operation display section 6 Memory section 7 Control Unit 8 Power supply unit 40 Load 41 Power supply 42 Power supply line 43 Switch 44 Inrush current suppression circuit 45 Voltage divider circuit 46 Snubber control circuit 71 Resistor 72 Capacitor 81 1st energizing path 82 2nd energizing path 91 Detection processing section 92 First determination processing unit 93 Second determination processing unit 94 Power supply control unit 100 Image forming device

Claims

1. a switch for switching between conduction and interruption of a power supply path between a power source and a load; an inrush current suppression circuit including a switching element provided between the switch and the load in the power supply path, the inrush current suppression circuit suppressing an inrush current that flows in response to a transition of the switch from an off state to an on state; a resistor and a capacitor connected in parallel between a specific section of the power supply path between the switch and the inrush current suppression circuit and ground; a detection processing unit that detects the voltage in the specific section at a predetermined detection period; a first determination processing unit that determines whether a transition time from an OFF state to an ON state of the switch has elapsed based on the change in the voltage detected by the detection processing unit; a second determination processing unit that determines, each time the voltage is detected by the detection processing unit after the switch has transitioned from an off state to an on state, whether the detected voltage is higher or lower than a target range corresponding to the number of times the voltage has been detected since the transition; an electric current control unit that, when it is determined that the detected voltage is higher than the target range, causes a first electric current path from the specific section to the ground via the resistor and a second electric current path from the specific section to the ground via the capacitor to be conductive; when it is determined that the detected voltage is within the target range, causes the first electric current path to be interrupted and the second electric current path to be conductive; and when it is determined that the detected voltage is lower than the target range, causes the first electric current path and the second electric current path to be interrupted; An electronic device comprising:

2. the target range is a range including a target value corresponding to the number of times the voltage is detected by the detection processing unit, the target value is set so as to gradually approach the voltage of the power supply as the number of times the detection processing unit detects the voltage increases. The electronic device according to claim 1 .

3. The image forming apparatus includes an image reading unit that reads an image of a document and / or an image forming unit that forms an image based on image data.

3. The electronic device according to claim 1 or 2.

4. A voltage control method executed in an electronic device including: a switch that switches between conduction and interruption of a power supply path between a power source and a load; an inrush current suppression circuit that includes a switching element provided between the switch and the load in the power supply path and that suppresses an inrush current that flows in response to a transition of the switch from an off state to an on state; and a resistor and a capacitor that are connected in parallel between a specific section in the power supply path between the switch and the inrush current suppression circuit and ground, a detection step of detecting a voltage in the specific section at a predetermined detection period; a first determination step of determining whether or not a transition time from an OFF state to an ON state of the switch has elapsed based on the change in the voltage detected in the detection step; a second determination step of determining whether the detected voltage is higher or lower than a target range corresponding to the number of times the voltage has been detected since the switch transitioned from an off state to an on state, each time the voltage is detected by the detection step; a current control step of conducting a first current path from the specific section to the ground via the resistor and a second current path from the specific section to the ground via the capacitor when it is determined that the detected voltage is higher than the target range, interrupting the first current path and making the second current path conductive when it is determined that the detected voltage is included in the target range, and interrupting the first current path and the second current path when it is determined that the detected voltage is lower than the target range; A voltage control method including:

Images