Power supply device and image forming apparatus

Abstract

To reduce vibration having a frequency in an audible range generated in a power supply device with a simple configuration.SOLUTION: The power supply device includes the capacitors 12 and 13 connected between the power supply line of the power supply device 3 and the ground, the coil 10 connected to the power supply line between the AC power supply 1 and the AC-DC converter 4, the switch element 11 connected in parallel with the coil 10 and configured to short-circuit both ends of the coil 10 by being turned on, and the main body control unit 6 configured to control the switch element 11 to be turned on or off.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a power supply device and an image forming apparatus, and for example, to an image forming apparatus equipped with a power supply device having a Y capacitor and a power factor correction coil. [Background technology]

[0002] Conventionally, power supplies mounted on image forming devices such as copiers and printers often have Y capacitors connected to their power lines as a measure for EMC (Electromagnetic Compatibility). Some capacitors, such as ceramic capacitors, have the property of expanding and contracting when a voltage is applied (electrostrictive effect), and vibrate in response to fluctuations in the applied voltage. The vibration of the ceramic capacitor itself and the circuit board on which the ceramic capacitor is mounted may vibrate at frequencies of several kHz to 15 kHz, which may be recognized as sound in the audible range. This phenomenon is hereinafter referred to as "audible noise." For example, Patent Document 1 proposes a method for reducing audible noise by placing a ceramic capacitor with vibration characteristics in the opposite phase near the ceramic capacitor to cancel out the vibration and reduce the audible noise generated from the circuit board. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-078137 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology, anti-phase capacitors and peripheral circuit components are required depending on the number of capacitors, which increases the size and cost of the board. Also, since it is not possible to cancel out the resonance between the ceramic capacitor and a coil located near the ceramic capacitor, it is difficult to reduce the audible noise caused by the resonance.

[0005] The present invention has been made under these circumstances, and has an object to reduce vibrations having frequencies in the audible range that are generated in a power supply device with a simple configuration. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention has the following configuration.

[0007] (1) A power supply device that outputs electric power, comprising: an AC-DC converter that converts AC voltage supplied from an AC power source via a power line into DC voltage; a capacitor connected between the power line of the power supply device and ground; a coil connected to the power line between the AC power source and the AC-DC converter; a switch element connected in parallel with the coil and that shorts both ends of the coil when turned on; and control means for controlling the switch element to be on or off, wherein the control means controls the switch element to be off when the output power is equal to or greater than a predetermined power, and controls the switch element to be on when the output power is less than the predetermined power.

[0008] (2) An image forming apparatus having an image forming means for forming an image on a recording material, capable of operating in a first mode for performing a printing operation and a second mode consuming less power than the first mode, characterized in that the image forming apparatus is equipped with the power supply device described in (1), and the control means controls the switch element to be off when operating in the first mode, and controls the switch element to be on when operating in the second mode. [Effects of the Invention]

[0009] According to the present invention, vibrations having frequencies in the audible range that are generated in a power supply device can be reduced with a simple configuration. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to first and second embodiments; [Figure 2] Configuration diagram of the power supply device of the first embodiment [Figure 3] 1 is a flowchart showing the on / off control of a switch element according to a first embodiment. [Figure 4] Graph showing noise levels in Examples 1 and 2 [Figure 5] Configuration diagram of power supply device of Example 2 [Figure 6] 10 is a flowchart showing the on / off control of a switch element according to a second embodiment. [Figure 7] 10 is a time chart showing the on / off control of the switch element according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0011] In the first embodiment, an electrophotographic laser beam printer is shown as an example of an image forming apparatus.

[0012] <Explanation of image forming device> FIG. 1 shows a schematic configuration of a laser beam printer 2 (hereinafter referred to as printer 2) according to a first embodiment. Paper P as a recording material loaded in a paper feed cassette 21 is transported to an image forming unit 23 by a paper feed transport unit 22. The image forming unit 23, which serves as an image forming means, includes a charging unit, a developing unit, and a cleaning unit (not shown), as well as a photosensitive drum 24 and a transfer unit 25. The surface of the photosensitive drum 24 is charged by the charging unit, and an electrostatic latent image is formed on the photosensitive drum 24 by laser light output from an exposure unit 26. The electrostatic latent image is then developed with toner by the developing unit, thereby forming a toner image on the photosensitive drum 24. The toner image formed on the photosensitive drum 24 is transferred by a transfer unit 25 to the transported paper P. The toner image transferred to the paper P is heated and pressurized by a fixing unit 27, thereby being fixed to the paper P. The paper P is then ejected from the printer 2. This series of controls is performed by a main body control unit 6.

[0013] The main body control unit 6 has, for example, a CPU (central processing unit), ROM (read only memory), RAM (random-access memory), and timer. The main body control unit 6 controls the printer 2 by using the CPU to execute programs pre-stored in the ROM while using the RAM as a temporary work area. When controlling the printer 2, the main body control unit 6 controls various timings using a timer. The main body control unit 6 may also include an ASIC (application specific integrated circuit) or an MPU (micro processing unit). The number of CPUs, timers, ROMs, and RAMs is not limited to one, and may be multiple. Furthermore, other storage media such as a hard disk or optical disk may also be used as the storage medium.

[0014] When the printer 2 finishes a print operation, after a predetermined time has elapsed, it can transition to a standby state in which it can immediately perform a print operation. After a further predetermined time has elapsed, the printer 2 can transition from the standby state to a sleep state, which is a low-power consumption mode, in order to reduce power consumption during standby. The printer 2 can operate in three states: a print state as a first mode, and a sleep state or standby state as a second mode which consumes less power than the print state, and the main body control unit 6 transitions the printer to each state.

[0015] The printer 2 also includes a power supply device 3 that supplies power to the above-mentioned components. As indicated by the dashed lines in Fig. 1, the power supply device 3 supplies a voltage V1 (described later) to the paper feed and transport unit 22, image forming unit 23, exposure unit 26, fixing unit 27, etc. (hereinafter referred to as the main body drive unit 8), and supplies a voltage V2 (described later) to the main body control unit 6. In the print mode, the power supply device 3 supplies the voltage V1 to the main body drive unit 8 and supplies the voltage V2 to the main body control unit 6. In the sleep mode and standby mode, the power supply device 3 cuts off the supply of voltage V1 to the main body drive unit 8 and supplies voltage V2 to the main body control unit 6.

[0016] <Power supply description> FIG. 2 shows a schematic configuration of the power supply device 3 of the first embodiment. The power supply device 3 has the following components and configuration: The inlet 7 is a connector for inserting a power cable, and inserting the power cable connected to the AC power supply 1 turns on the AC power supply 1 to the power supply device 3. Of the two power supply lines between the inlet 7 and the AC-DC converter 4 (described later), a coil 10 (first coil) provided on the NEUTRAL line is a power factor correction coil for widening the conduction angle of the input current of the power supply device 3. The switch element 11 is connected in parallel to the coil 10, i.e., to both ends of the input and output of the coil 10, and when the switch element 11 is turned on, the coil 10 is short-circuited. Examples of the switch element 11 include a triac and an electromagnetic relay. The on / off of the switch element 11 is controlled by the main body control unit 6, which serves as control means.

[0017] Capacitor 12a as a first capacitor and capacitor 13a as a third capacitor arranged between the LIVE line and ground are Y capacitors (bypass capacitors). Capacitor 12b as a second capacitor and capacitor 13b as a fourth capacitor arranged between the NEUTRAL line and ground are also Y capacitors (bypass capacitors). Capacitor 12a and capacitor 12b are connected in series, and ground is connected between capacitor 12a and capacitor 12b. Capacitor 13a and capacitor 13b are connected in series, and ground is connected between capacitor 13a and capacitor 13b.

[0018] Capacitors 12a and 12b are collectively referred to as capacitors 12 as a first capacitor group, and capacitors 13a and 13b are collectively referred to as capacitors 13 as a second capacitor group. Capacitors 12 and 13 are provided to reduce common-mode noise in power supply device 3. Common-mode coil 14 (coil, second coil) is disposed between capacitors 12 and 13 and is provided to reduce common-mode noise in power supply device 3. Capacitor 15 as a fifth capacitor and capacitor 16 as a sixth capacitor disposed between the LIVE line and the NEUTRAL line are X capacitors (across-the-line capacitors) and are provided to reduce normal-mode noise in power supply device 3. Capacitor 15 can also be said to be connected between capacitor 12 and common-mode coil 14. Capacitor 16 can also be said to be connected between capacitor 13 and common-mode coil 14.

[0019] The AC-DC converter 4 rectifies and smoothes the AC voltage of the AC power supply 1 input to the power supply device 3, and generates a voltage V1 that is stepped down to a predetermined voltage. The voltage V1 is a voltage used by the motors and electric boards that operate the main body drive unit 8, and is, for example, a DC voltage of 24 V. As described above, the main body drive unit 8 is composed of the paper feed conveyance unit 22, the image forming unit 23, the exposure unit 26, the fixing unit 27, and the like. The voltage V1 is also input to the DC-DC converter 5, which steps down the voltage V1 to generate a voltage V2 that is used by the main body control unit 6 and the like. The voltage V2 is, for example, a DC voltage of 3.3 V.

[0020] <Explanation of switch element control> FIG. 3 shows a flowchart of the control method for the switch element 11 in the first embodiment. The following explanation will be given with reference to the flowchart. In step (hereinafter referred to as S) 11, when the AC power supply 1 is turned on to the inlet 7, the printer 2 enters a sleep or standby state waiting for a print instruction from the user. The power supply device 3 is equipped with a coil 10, and resonance between the coil 10 and capacitors 12 and 13 causes the above-mentioned noise due to vibration of the capacitor and circuit board. When the printer 2 is in a sleep or standby state, the operating noise of the printer 2 itself is small and quiet, making it relatively easy for the user to hear the noise.

[0021] In S12, the main body control unit 6 controls the switch element 11 to turn on when the printer 2 enters the sleep mode or standby mode in order to suppress noise. When the switch element 11 is turned on, the coil 10 is shorted, which eliminates vibrations caused by resonance between the coil 10 and the capacitors 12 and 13, thereby suppressing noise.

[0022] (Noise measurement results during sleep) Figure 4 shows an example of noise measurement results for the printer 2 when it is in sleep mode. During sleep mode, the supply of voltage V1 to the main body drive unit 8 is cut off, and the main body drive unit 8 is stopped, resulting in a quieter state than when the main body drive unit 8 is operating. The vertical axis represents the noise level in decibels (dB), and the horizontal axis represents frequency (kHz), showing a comparison of noise levels before and after the coil 10 is shorted. The dashed line represents the noise level when the switch element 11 is off, and the solid line represents the noise level when the switch element 11 is on (when the coil 10 is shorted). When the switch element 11 is off, a maximum noise level of approximately 27 dB is generated in the frequency range of 5 kHz to 8 kHz. In contrast, when the switch element 11 is on (when the coil 10 is shorted), the noise level is at most approximately 16 dB in the same frequency range, a reduction of more than 10 dB compared to when the switch element 11 is off.

[0023] In a quiet environment around the user, if sounds with frequencies of about several kHz to 15 kHz exceed 20 dB, the user may find them uncomfortable. In the present invention, by turning on switch element 11, sounds with frequencies of about several kHz to 15 kHz can be reduced to 16 dB or less, reducing the noise level to a level that the user will not find uncomfortable. Note that turning on switch element 11 to short-circuit coil 10 will cause the power factor correction function to be lost, but this function does not need to be exercised when printer 2 is in a low-power consumption state, such as a sleep state or standby state. In other words, there is no problem as long as the power factor correction function is maintained when the printer 2 is in a high-power consumption state, such as when it is printing.

[0024] Returning to the explanation of the flowchart in FIG. 3, in S13 the main body control unit 6 determines whether or not a print instruction has been received from the user. If in S13 the main body control unit 6 determines that a print instruction has not been received, the process returns to S12 and keeps the switch element 11 in the on state. If in S13 the main body control unit 6 determines that a print instruction has been received, the process proceeds to S14. In S14 the main body control unit 6 turns off the switch element 11 before starting the print operation. In S15 the main body control unit 6 executes the print operation. In this way, the main body control unit 6 executes the print operation after turning off the switch element 11 and enabling the power factor correction function of the power supply device 3.

[0025] In S16, the main body control unit 6 completes the printing operation. In S17, the printer 2 transitions to a sleep or standby state. In S18, the main body control unit 6 controls the switch element 11 to turn on, shorting the coil 10 and completing the series of processes.

[0026] According to the first embodiment, when the printer 2 is in a sleep state or a standby state, the main body control unit 6 turns on the switch element 11 to short-circuit the coil 10, thereby eliminating resonance between the coil 10 and the capacitors 12 and 13, thereby making it possible to suppress noise. In the first embodiment, the main body control unit 6 switches the switch element 11 on and off depending on the mode of the printer 2. That is, it can be said that the main body control unit 6 controls the switch element 11 to be off when the output power is equal to or greater than a predetermined power, and controls the switch element 11 to be on when the output power is less than the predetermined power.

[0027] The control of the switch element 11 of the present invention may be configured so that the user can select whether to enable or disable this function. Specifically, the user can enable or disable this function via an operation panel, operation buttons, or the like (not shown) provided on the printer 2. That is, the printer 2 may be provided with a setting means, and the setting means may be used to set whether the on / off control of the switch element 11 is enabled or disabled. Note that when enabled, the main body control unit 6 controls the on / off of the switch element 11. On the other hand, when disabled, the main body control unit 6 does not control the on / off of the switch element 11, but always keeps the switch element 11 off, and always enables the power factor correction function of the coil 10.

[0028] As described above, according to the first embodiment, it is possible to reduce vibrations having frequencies in the audible range that are generated in the power supply device with a simple configuration. [Example]

[0029] In the second embodiment, differences from the first embodiment will be mainly described with reference to Figures 5, 6, and 7. In the first embodiment, the main body control unit 6 switches on and off the switch element 11 depending on the mode of the printer 2. In the second embodiment, the main body control unit 6 switches on and off the switch element 11 depending on the detection result of the current.

[0030] <Power supply description> FIG. 5 shows a schematic configuration of the power supply device 3 of the second embodiment. The same components as those in FIG. 2 are assigned the same reference numerals, and their descriptions will be omitted. A current detection unit 9 serving as a detection unit detects the current supplied from the AC power supply 1 to the power supply device 3 and outputs the detection result to a switch control unit 17 serving as a control unit. The current detection unit 9 is composed of electrical components including, for example, a current transformer, and converts the secondary current obtained by the current transformer into a voltage value V and outputs the voltage value V to the switch control unit 17. In the second embodiment, the on / off control of the switch element 11 is performed by the switch control unit 17. The switch control unit 17 controls the switch element 11 so that it turns on when the input voltage value V is less than a predetermined value, and turns off when the voltage value V is equal to or greater than the predetermined value. In other words, the switch control unit 17 controls the switch element 11 so that it turns on (shorting the coil 10) when the detected current value is less than the predetermined value, and turns off when the detected current value is equal to or greater than the predetermined value.

[0031] <Explanation of switch element control> FIG. 6 shows a flowchart relating to the control method for the switch element 11 of the second embodiment. The following description will be given with reference to the flowchart. In S21, the current detection unit 9 detects the value of the current supplied from the AC power supply 1 to the power supply device 3. Note that the current detection unit 9 constantly detects the current value while the printer 2 is operating, regardless of the operating state of the printer 2. In S22, the current detection unit 9 converts the detection result into a voltage value V and outputs the voltage value V to the switch control unit 17. In S23, the switch control unit 17 compares the input voltage value V with a predetermined threshold value Vth and determines whether the voltage value V is equal to or greater than the threshold value Vth.

[0032] In S23, when the switch control unit 17 determines that the voltage value V is greater than or equal to the threshold value Vth, the process proceeds to S24. In S24, the switch control unit 17 controls the switch element 11 to turn off and ends the process. In S23, when the switch control unit 17 determines that the voltage value V is less than the threshold value Vth, the process proceeds to S25. In S25, the switch control unit 17 controls the switch element 11 to turn on and ends the process. Thus, in the second embodiment, when the current value supplied from the AC power supply 1 to the power supply device 3 is less than the predetermined value, the coil 10 is short-circuited and becomes ineffective, and when the current value is greater than or equal to the predetermined value, the coil 10 functions.

[0033] <State of the switch element> The control method of the switch element 11 will be described using FIG. 7. FIG. 7 is a time chart showing the time changes of the voltage value V output from the current detection unit 9, the operating state of the printer 2, and the state of the switch element 11. (i) shows the time T on the horizontal axis and the voltage value V on the vertical axis, and the threshold value Vth is shown by a dashed line; (ii) shows the operating state (sleep, print, standby) of the printer 2; (iii) shows the state (on, off) of the switch element 11.

[0034] During the period from time t0 to time t1, the printer 2 is in the sleep state, and the voltage value Va is output from the current detection unit 9 to the switch control unit 17. Since the voltage value Va is less than the threshold value Vth (Va < Vth), the switch control unit 17 controls the switch element 11 to turn on. At time t1, when the user gives a print instruction to the printer 2, the printer 2 starts the print operation, and the print operation continues until time t2 when the printing is completed. During the period from time t1 to time t2, the voltage value Vc is output from the current detection unit 9 to the switch control unit 17. Since the voltage value Vc is greater than or equal to the threshold value Vth (Vc ≥ Vth), the switch control unit 17 controls the switch element 11 to turn off.

[0035] When the printer 2 stops the printing operation at time t2, it shifts to the standby state, and then the standby state continues until time t3 when it shifts to the sleep state. During the period from time t2 to time t3, the voltage value Vb is output from the current detection unit 9 to the switch control unit 17. Since the voltage value Vb is less than the threshold value Vth (Vb < Vth), the switch control unit 17 controls the switch element 11 to be turned on. Note that the voltage value Vb in the standby state is greater than the voltage value Va in the sleep state (Vb > Va).

[0036] The printer 2 shifts to the sleep state at time t3. After time t3, the voltage value Va is output from the current detection unit 9 to the switch control unit 17. Since the voltage value Va is less than the threshold value Vth (Va < Vth), the switch control unit 17 controls to maintain the switch element 11 in the on state.

[0037] As described above, according to the second embodiment, when the current value supplied to the power supply device 3 increases, it becomes possible to turn on the switch element 11 at the optimal timing when the coil 10 should be activated. Further, since it is possible to suppress the buzzing sound due to the resonance of the coil 10 and the capacitors 12 and 13 only by the power supply device 3 without passing through the main control unit 6, the interface between the main control unit 6 and the power supply device 3 can be simplified. Note that it is also possible to suppress the buzzing sound in a configuration where the detection result of the current detection unit 9 is output to the main control unit 6 and the main control unit 6 controls the on / off of the switch element 11 based on the detection result of the current detection unit 9.

[0038] As described above, according to the second embodiment, vibrations having frequencies in the audible range generated by the power supply device can be reduced with a simple configuration.

[0039] <Other Embodiments> The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiment to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. Further, it can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

[0040] The disclosure of this embodiment includes the following configuration. (Configuration 1) A power supply device that outputs electric power, an AC / DC converter that converts AC voltage supplied from an AC power source via a power line into DC voltage; a capacitor connected between the power supply line of the power supply device and ground; a coil connected to the power supply line between the AC power supply and the AC / DC converter; a switch element connected in parallel with the coil and shorting both ends of the coil when turned on; a control means for controlling the switch element to be on or off; Equipped with The power supply device is characterized in that the control means controls the switch element to be off when the output power is equal to or greater than a predetermined power, and controls the switch element to be on when the output power is less than the predetermined power. (Configuration 2) 2. The power supply device according to claim 1, wherein the capacitor is a ceramic capacitor. (Configuration 3) the capacitor is a first capacitor; a second capacitor connected in series with the first capacitor; 2. The power supply device according to configuration 1, wherein a ground is connected between the first capacitor and the second capacitor. (Configuration 4) the capacitors include a third capacitor and a fourth capacitor connected in series with the third capacitor; 4. The power supply device according to configuration 3, wherein a ground is connected between the third capacitor and the fourth capacitor. (Configuration 5) The coil is a first coil, the first capacitor and the second capacitor constitute a first capacitor group; When the third capacitor and the fourth capacitor are defined as a second capacitor group, 5. The power supply device according to configuration 4, further comprising a second coil connected between the first capacitor group and the second capacitor group. (Configuration 6) The power supply device according to configuration 5, wherein a fifth capacitor is connected between the first capacitor group and the second coil. (Configuration 7) 7. The power supply device according to configuration 6, wherein a sixth capacitor is connected between the second capacitor group and the second coil. (Configuration 8) 8. The power supply device according to configuration 7, wherein the first coil is connected between the first capacitor group and the AC power supply. (Configuration 9) a detection means for detecting a current value flowing through the power supply line, The power supply device according to any one of configurations 1 to 8, wherein the control means controls the switch element to be off when the current value detected by the detection means is equal to or greater than a predetermined value, and controls the switch element to be on when the current value detected by the detection means is less than the predetermined value. (Configuration 10) a setting unit that sets the control unit to turn on or off the switch element to valid or invalid, The power supply device according to any one of configurations 1 to 9, wherein the control means controls the on or off of the switch element when the setting means sets the enable state, and turns the switch element off when the setting means sets the disable state. (Configuration 11) an image forming means for forming an image on a recording material; An image forming apparatus that can operate in a first mode for performing a printing operation and a second mode that consumes less power than the first mode, a power supply device according to any one of configurations 1 to 10; The image forming apparatus is characterized in that the control means controls the switch element to be off when operating in the first mode, and controls the switch element to be on when operating in the second mode. (Configuration 12) The image forming apparatus according to configuration 11, wherein the control means controls the switch element to be turned off before starting the printing operation when transitioning from the second mode to the first mode, and controls the switch element to be turned on after completing the printing operation when transitioning from the first mode to the second mode. [Explanation of symbols]

[0041] 1 AC power supply 3 Power supply 4 AC / DC converters 6 Main unit control section 10 Coil (power factor correction coil) 11 Switching element 12, 13 Capacitor (bypass capacitor)

Claims

1. A power supply device that outputs electric power, an AC-DC converter that converts AC voltage supplied from an AC power source via a power line into DC voltage; a capacitor connected between the power supply line of the power supply device and ground; a coil connected to the power supply line between the AC power supply and the AC-DC converter; a switch element connected in parallel with the coil and shorting both ends of the coil when turned on; a control means for controlling the switch element to be on or off; Equipped with The power supply device is characterized in that the control means controls the switch element to be off when the output power is equal to or greater than a predetermined power, and controls the switch element to be on when the output power is less than the predetermined power.

2. 2. The power supply device according to claim 1, wherein the capacitor is a ceramic capacitor.

3. the capacitor is a first capacitor; a second capacitor connected in series with the first capacitor; 2. The power supply device according to claim 1, wherein a ground is connected between the first capacitor and the second capacitor.

4. the capacitors include a third capacitor and a fourth capacitor connected in series with the third capacitor; 4. The power supply device according to claim 3, wherein a ground is connected between the third capacitor and the fourth capacitor.

5. The coil is a first coil, the first capacitor and the second capacitor constitute a first capacitor group; When the third capacitor and the fourth capacitor are defined as a second capacitor group, 5. The power supply device according to claim 4, further comprising a second coil connected between the first capacitor group and the second capacitor group.

6. 6. The power supply device according to claim 5, wherein a fifth capacitor is connected between the first capacitor group and the second coil.

7. 7. The power supply device according to claim 6, wherein a sixth capacitor is connected between the second capacitor group and the second coil.

8. 8. The power supply device according to claim 7, wherein the first coil is connected between the first capacitor group and the AC power supply.

9. a detection means for detecting a current value flowing through the power supply line, 2. The power supply device according to claim 1, wherein the control means controls the switch element to be off when the current value detected by the detection means is equal to or greater than a predetermined value, and controls the switch element to be on when the current value detected by the detection means is less than the predetermined value.

10. a setting unit that sets the control unit to turn on or off the switch element to valid or invalid, 2. The power supply device according to claim 1, wherein the control means controls the on or off of the switch element when the setting means sets the enable state, and turns the switch element off when the setting means sets the disable state.

11. an image forming means for forming an image on a recording material; An image forming apparatus that can operate in a first mode for performing a printing operation and a second mode that consumes less power than the first mode, A power supply device according to any one of claims 1 to 10, The image forming apparatus is characterized in that the control means controls the switch element to be off when operating in the first mode, and controls the switch element to be on when operating in the second mode.

12. 12. The image forming apparatus according to claim 11, wherein the control means controls the switch element to be turned off before starting the printing operation when transitioning from the second mode to the first mode, and controls the switch element to be turned on after completing the printing operation when transitioning from the first mode to the second mode.

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