Power supply device

Abstract

To provide a power supply device that, even when output voltage output from a power supply voltage generation unit is unstable, can stabilize the output voltage to an arithmetic processing unit after a transition to a power saving mode.SOLUTION: When the operation mode of an image forming apparatus is switched to a power saving mode, output voltage output from a power supply circuit to a main control unit is stepped down to have a voltage value obtained by subtracting a correction value based on a prescribed step-down correction value (first step-down correction value, or second step-down correction value) from a reference voltage V0.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a power supply device for electrical equipment. [Background technology]

[0002] Image processing devices such as copiers, printers, facsimiles, and image readers may operate in a power-saving mode to reduce power consumption. In the power-saving mode, the power supply from the power supply device of the image processing device to operational processing units such as an image forming unit and a sheet conveying unit is cut off.

[0003] The power supply device also supplies power to a main control board (arithmetic processing unit) that controls the image processing device. The power supply device is provided with a power supply voltage generation unit that converts an externally input DC or AC voltage into a predetermined DC voltage value required by the main control board and supplies it. The power supply voltage generation unit is, for example, an AC / DC converter or a DC / DC converter.

[0004] Conventionally, Patent Document 1 discloses a fuel cell power supply device that detects the output voltage and output current of a fuel cell and adjusts the output voltage of the fuel cell so that the output voltage of the fuel cell matches a target voltage. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-251674 Summary of the Invention [Problem to be solved by the invention]

[0006] Depending on the country or region where the image processing device is used, the power transmitted to the facility where the image processing device is installed may not be stable. In this case, the output voltage output from the power supply voltage generation unit of the power supply device may be unstable and vary. Even if the transmitted power is stable, for example, the resistance and output values ​​of each electronic device used in the power supply voltage generation unit, such as voltage dividing resistors, switching elements, coils, and capacitors, have tolerances. Therefore, even if the power supply voltage generation unit is composed of inexpensive electronic devices with relatively low precision, the output voltage output from the power supply voltage generation unit may vary.

[0007] An object of the present invention is to provide a power supply device that can stabilize the output voltage to the calculation processing unit after transitioning to a power saving mode, even if the output voltage output from the power supply voltage generation unit is unstable. [Means for solving the problem]

[0008] A power supply device according to one aspect of the present invention comprises a power supply voltage generation unit that outputs a voltage to an arithmetic processing unit that controls an operation processing unit provided in an electrical device, and a power supply control unit that, when the operation mode of the electrical device is switched to a power saving mode that suppresses the supply of power to the operation processing unit, reduces the output voltage output from the power supply voltage generation unit to the arithmetic processing unit to a voltage value obtained by subtracting a correction value based on a predetermined specified step-down correction value from a reference operating voltage required when the operation processing unit is operating. [Effects of the Invention]

[0009] According to the present invention, even if the output voltage output from the power supply voltage generating section is unstable, it is possible to stabilize the output voltage to the arithmetic processing section after transition to the power saving mode. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2]FIG. 2 is a flowchart showing an example of the procedure of the output voltage adjustment process executed in the power supply device according to the embodiment of the present invention. [Figure 3] FIG. 3 is a flowchart showing another example of the procedure of the output voltage adjustment process executed in the power supply device 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 the present invention, and does not limit the technical scope of the present invention.

[0012] [Image forming apparatus 10] The configuration of an image forming apparatus 10 according to an embodiment of the electrical equipment of the present invention will be described with reference to Figure 1. Note that in this embodiment, the image forming apparatus 10 will be described as an example of the electrical equipment of the present invention, but the electrical equipment of the present invention may also be an image processing apparatus such as a printer, facsimile machine, copier, scanner, or a multifunction peripheral having the functions of each of these.

[0013] As shown in Fig. 1, image forming apparatus 10 includes an image reading unit 11, an image forming unit 12, an operation and display unit 13, a paper feed unit 14, and a communication unit 19 as drive processing units of the present invention. Image forming apparatus 10 also includes a main control unit 20 (an example of an arithmetic processing unit of the present invention) that is a main controller that controls each of these drive processing units. Each of these components is provided in a housing of image forming apparatus 10. Image forming apparatus 10 also includes a power supply unit 30 (an example of a power supply device of the present invention) that supplies the voltage and current required for image reading unit 11, image forming unit 12, operation and display unit 13, paper feed unit 14, communication unit 19, main control unit 20, etc. In Fig. 1, power lines are indicated by solid lines, and signal lines are indicated by dashed lines.

[0014] The image reading unit 11, image forming unit 12, operation and display unit 13, and paper feed unit 14 each have a drive unit that consumes power to operate, and are loads in the image forming apparatus 10. Examples of the drive unit include a motor, a liquid crystal display, a light source, and a sensor. For ease of explanation, the image reading unit 11, image forming unit 12, operation and display unit 13, and paper feed unit 14 will be collectively referred to as load unit 15 below.

[0015] The image reading unit 11 is a so-called scanner equipped with a contact glass, a reading unit, a mirror, an optical lens, a CCD, and the like. The image reading unit 11 executes an image reading process to read image data from a document set at a predetermined position. Specifically, the document is placed on the contact glass, and then an image reading instruction is input from the operation display unit 13. The reading unit is then moved in the sub-scanning direction by a built-in drive motor. During this movement, light is continuously irradiated onto the document in succession by one line of light from the light source of the reading unit. The reflected light from the document is then guided to the CCD via the mirror and the optical lens, and light intensity data corresponding to the amount of light received by the CCD is output to the main control unit 20. The main control unit 20 generates image data of the document based on the optical data.

[0016] Image forming unit 12 performs an image formation process (printing process) based on electrophotography. Specifically, image forming unit 12 performs the image formation process based on image data read by image reading unit 11 or print data (print job) input via communication unit 19 from an external information processing device such as a personal computer. Image forming unit 12 includes a photosensitive drum, a charging device, a developing device, a transfer device, a fixing device, a laser scanner unit, and the like. When the print data is input, the charging device uniformly charges the photosensitive drum to a predetermined potential. Next, the laser scanner unit irradiates the surface of the photosensitive drum with light based on the image data included in the print job. This forms an electrostatic latent image on the surface of the photosensitive drum. The electrostatic latent image on the photosensitive drum is then developed into a toner image by the developing device. The toner image formed on the photosensitive drum is then transferred to printing paper (sheet material) by the transfer device and then fixed to the printing paper by the fixing device. In this embodiment, an electrophotographic image forming unit 12 will be described as an example, but the image forming unit 12 is not limited to an electrophotographic image forming unit, and may be an inkjet recording unit, or may be any other recording or printing unit.

[0017] The main control unit 20 comprehensively controls the image forming apparatus 10. The main control unit 20 is configured as a control board on which a microcomputer is mounted, the main components of which are electronic devices and integrated circuits, such as a CPU 21, a ROM 22, a RAM 23, and a storage unit 24 such as a flash memory.

[0018] In this embodiment, the main control unit 20 is configured as an integrated circuit known as a system on a chip (SoC), which is an integrated circuit in which all components necessary for controlling the image scanning unit 11, image forming unit 12, operation / display unit 13, paper feed unit 14, and communication unit 19 of the image forming apparatus 10 are mounted on a single semiconductor substrate (silicon wafer). For example, the main control unit 20 is equipped with a data processing unit for processing image data, storage devices such as a ROM 22, a RAM 23, and a storage unit 24, a graphics processing unit (GPU), a communication interface for USB communication, and an interface for data communication based on I2C (Inter-Integrated Circuit) (hereinafter referred to as I2C communication). The main control unit 20 may also be configured as an integrated circuit known as an ASIC or a system LSI.

[0019] 1, the main control unit 20 is connected to the load unit 15 and the communication unit 19 via an internal bus so that they can communicate with each other. The main control unit 20 comprehensively controls the image forming apparatus 10 by the CPU executing the program stored in the ROM.

[0020] The communication unit 19 connects the image forming apparatus to a predetermined communication network and receives input of print data and the like transmitted from the outside via the communication network. Specifically, the communication unit 19 is a communication interface card or the like that complies with the standard IEEE802.3. The print data sent to the image forming apparatus 10 from the outside is input via the communication unit 19.

[0021] The operation and display unit 13 includes an operation unit such as a push button switch and a display unit such as a liquid crystal panel. The operation and display unit 13 is equipped with a panel control unit including a liquid crystal driver. The panel control unit recognizes signals input from the operation unit. The panel control unit also executes display processing of various data on the display unit.

[0022] The paper feed unit 14 stores printing paper on which an image is formed in the image forming unit 12. The paper feed unit 14 also includes a feeding mechanism (not shown), which feeds the printing paper stored in the paper feed unit 14 toward the image forming unit 12. The feeding mechanism is made up of a feeding roller and a drive motor that drives and rotates the feeding roller, and the drive motor is driven and rotated as needed, causing the feeding roller to feed the printing paper.

[0023] The main control unit 20 controls switching of the operation mode of the image forming apparatus 10 between a power saving mode and a normal operation mode. The normal operation mode is an operation mode in which power is supplied from the power supply unit 30 to the load unit 15, the main control unit 20, etc. to operate them. The power saving mode is an operation mode in which power supply from the power supply unit 30 to the load unit 15 is stopped to reduce power consumption. In the power saving mode, power is supplied to only some of the components, such as the main control unit 20 and the communication unit 19, to operate them.

[0024] The power saving mode is an operation mode that has a higher power saving effect than the normal operation mode. For example, when the main power of the image forming apparatus 10 is turned on, the image forming apparatus 10 operates in the normal operation mode and maintains a state of waiting for input of a print job or an instruction to execute an image forming process. If no events such as input of a print job, an instruction to execute an image forming process, or an operation on the operation display unit 13 occur for a certain period of time (predetermined power saving transition condition), the main control unit 20 switches the operation mode of the image forming apparatus 10 from the normal operation mode to the power saving mode. At that time, the power supply from the power supply unit 30 to the load unit 15 is stopped.

[0025] [Power Supply Unit 30] The power supply unit 30 supplies the necessary power to each component, such as the image reading unit 11, the image forming unit 12, the operation display unit 13, the paper feed unit 14, the communication unit 19, and the main control unit 20. The power supply unit 30 is connected to each component by a power line.

[0026] The power supply unit 30 has a power supply control unit 31 (an example of a power supply control unit of the present invention), a power supply circuit 32 (an example of a power supply voltage generation unit of the present invention), and a voltage detection unit 33 (an example of a voltage detection unit of the present invention).

[0027] The power supply circuit 32 includes an AC / DC converter, a DC / DC converter, etc., and, for example, rectifies commercial power (e.g., AC 100V) and converts it to DC 24V, which is then subjected to switching control to be converted into a voltage appropriate for each component such as the main control unit 20 and the image forming unit 12, before being supplied to each component.

[0028] In this embodiment, the power supply circuit 32 has a conventionally known voltage adjustment function that can adjust the output voltage output from the power supply circuit 32 to the main control unit 20 based on a correction command from the power supply control unit 31.

[0029] The power supply control unit 31 controls the supply of power output from the power supply circuit 32 to each load unit 15 , the main control unit 20 , and the communication unit 19 .

[0030] 1, in this embodiment, the voltage output terminal Vout of the power supply circuit 32 and the voltage input terminal Vin of the main control unit 20 are connected by a power supply line L1, and a reference voltage V0 required for the main control unit 20 is supplied through the power supply line L1. Note that in FIG. 1, the voltage supply path from the power supply circuit 32 to other components such as the image forming unit 12 is not shown.

[0031] The power supply control unit 31 is configured as a control board on which a microcomputer whose main components are a CPU, ROM, RAM, etc. Specifically, the power supply control unit 31 is a power supply IC called a Power Management IC (PMIC).

[0032] The power supply control unit 31 executes an output voltage adjustment process (see FIGS. 2 and 3) described below by the CPU executing a predetermined control program stored in the ROM, thereby adjusting the output voltage output from the power supply circuit 32 to the main control unit 20. In the output voltage adjustment process, when the operation mode of the image forming apparatus 10 is switched from the normal operation mode to the power saving mode, the power supply control unit 31 performs a process of stepping down the output voltage output from the power supply circuit 32 to the main control unit 20 to a voltage value obtained by subtracting a correction value based on a predetermined specified step-down correction value from a reference voltage V0 (an example of the reference operation voltage of the present invention).

[0033] More specifically, the power supply control unit 31 calculates the voltage difference ΔV between the reference voltage V0 and the detected voltage detected by the voltage detection unit 33 after the transition to the power saving mode, and corrects the output voltage output from the power supply circuit 32 to the main control unit 20 in the power saving mode based on the voltage difference ΔV and the specified step-down correction value.

[0034] Here, the reference voltage V0 is a voltage value required for the main control unit 20 when the load units 15, such as the image reading unit 11 and the image forming unit 12, are operable in the normal operation mode. In other words, the reference voltage V0 is a voltage value required for the main control unit 20 when the image forming apparatus 10 is in the normal operation mode. The reference voltage V0 is a predetermined set value, and in this embodiment, the reference voltage V0 is set to 0.9 [V].

[0035] The specified step-down correction value is a correction value for correcting the output voltage output from the power supply circuit 32 to the main control unit 20 when the operation mode of the image forming apparatus 10 is shifted from the normal operation mode to the power saving operation mode. The specified step-down correction value is a predetermined setting value, and in this embodiment, the specified step-down correction value is set to 0.1 [V].

[0036] In addition to the control program, the reference voltage V0 is stored in the ROM of the power supply control unit 31. In addition to the reference voltage V0, the ROM also stores various data, information, thresholds, and the like used in the output voltage adjustment process (see FIGS. 2 and 3) described below.

[0037] The voltage detection unit 33 is a voltage detector that detects the voltage value of the output voltage output from the power supply circuit 32 to the main control unit 20. The voltage detection unit 33 detects the voltage between the power supply line L1 and the ground line, and transmits the detected voltage V1 to the power supply control unit 31.

[0038] Depending on the country or region where the image forming apparatus 10 is used, the power transmitted to the facility where the image forming apparatus 10 is installed may not be stable. In this case, the output voltage output from the power supply circuit 32 of the power supply unit 30 to the main control unit 20 may be unstable and may vary. Furthermore, for example, the resistance and output values ​​of each of the electronic devices used in the power supply circuit 32, such as voltage dividing resistors, switching elements, coils, and capacitors, contain tolerances. Therefore, even if the transmitted power is stable, the output voltage output from the power supply circuit 32 may vary if the power supply circuit 32 is made up of inexpensive electronic devices with relatively low precision.

[0039] In this embodiment, the power supply control unit 31 performs an output voltage adjustment process (see FIGS. 2 and 3) described below. As a result, even if the output voltage from the power supply circuit 32 is unstable, it is possible to stabilize the output voltage to the main control unit 20 after the image forming apparatus 10 transitions from the normal operation mode to the power saving mode.

[0040] [Output voltage adjustment process] An example of the procedure for output voltage adjustment processing executed by the power supply control unit 31 will be described below with reference to the flowcharts of Figures 2 and 3. In the figures, S11, S12, ... represent the numbers of the processing procedures (steps). The processing of each step is performed by the CPU of the power supply control unit 31 executing a program in the ROM. Note that the processing of each step described below is not limited to being realized by arithmetic processing by the power supply control unit 31, and some or all of the processing of each step may be implemented by electronic circuits.

[0041] The output voltage adjustment process is executed when the operation mode of the image forming apparatus 10 is switched from the normal operation mode to the power saving mode.

[0042] In step S11, the power supply control unit 31 determines whether the image forming apparatus 10 has been switched to the power saving mode. For example, when the above-mentioned power saving transition condition is satisfied, the main control unit 20 switches the operation mode of the image forming apparatus 10 from the normal operation mode to the power saving mode. At this time, the main control unit 20 outputs a switching signal to the power supply control unit 31. Upon receiving the switching signal, the power supply control unit 31 can determine that the image forming apparatus 10 has been switched to the power saving mode.

[0043] In step S12, after the image forming apparatus 10 is switched to the power saving mode, the voltage detection unit 33 detects the output voltage output from the power supply circuit 32 to the main control unit 20 through the power supply line L1.

[0044] In the next step S13, the power supply control unit 31 obtains a reference voltage V0 (an example of a reference operating voltage of the present invention) to be compared with the detected voltage V1 detected in step S12. The reference voltage V0 is a voltage value required for the main control unit 20 when the image forming apparatus 10 is in the normal operating mode, and is a predetermined value. In this embodiment, the reference voltage V0 is set to 0.9 V.

[0045] In the next step S14, the power supply control unit 31 calculates the voltage difference ΔV between the detected voltage V1 and the reference voltage V0.

[0046] Once the voltage difference ΔV is calculated, the power supply control unit 31 performs the processing from the next step S15 onwards, thereby correcting the output voltage output from the power supply circuit 32 to the main control unit 20 in the power saving mode based on the voltage difference ΔV and the specified step-down correction value (e.g., 0.1 [V]).

[0047] Specifically, first, in step S15, the power supply control unit 31 determines whether the detected voltage V1 is greater than the reference voltage V0. If the detected voltage V1 is greater than the reference voltage V0, the power supply control unit 31 proceeds to step S16. On the other hand, if the detected voltage V1 is not greater than the reference voltage V0, that is, if the detected voltage V1 is equal to or less than the reference voltage V0, the power supply control unit 31 proceeds to step S18.

[0048] If it is determined in step S15 that the detected voltage V1 is greater than the reference voltage V0 (for example, 0.9 V), the power supply control unit 31 calculates a first step-down correction value in the next step S16. Specifically, the power supply control unit 31 calculates a value obtained by adding the absolute value of the voltage difference ΔV to the specified step-down correction value as the first step-down correction value.

[0049] For example, if the detected voltage V1 is 0.98 [V] and the specified step-down correction value is 0.1 [V], the absolute value of the voltage difference ΔV is 0.08 [V], so the first step-down correction value is calculated as 0.18 [V] (= 0.1 + 0.08 [V]).

[0050] Then, in the next step S17, the power supply control unit 31 corrects the output voltage output from the power supply circuit 32 to the main control unit 20 in the power saving mode using the first step-down correction value. Specifically, the power supply control unit 31 steps down the output voltage to a voltage value obtained by subtracting the first step-down correction value from the detected voltage V1. In this case, the power supply control unit 31 outputs a correction command (correction signal) to the power supply circuit 32 to step down the current output voltage by the first step-down correction value. As a result, the power supply circuit 32 steps down the output voltage in accordance with the correction command.

[0051] For example, if the detected voltage V1 is 0.98 [V], the output voltage is stepped down to a voltage value of 0.8 [V] obtained by subtracting the first step-down correction value (0.18 [V]) from the detected voltage V1. Then, the series of processes ends.

[0052] On the other hand, if it is determined in step S15 that the detected voltage V1 is not greater than the reference voltage V0 (e.g., 0.9 [V]), the power supply control unit 31 determines in the next step S18 whether the detected voltage V1 is the same as the reference voltage V0.

[0053] If it is determined in step S18 that the detected voltage V1 is not equal to the reference voltage V0 and is lower than the reference voltage V0, the power supply control unit 31 calculates a second step-down correction value in the next step S19. Specifically, the power supply control unit 31 calculates the second step-down correction value by subtracting the absolute value of the voltage difference ΔV from the specified step-down correction value.

[0054] For example, if the detected voltage V1 is 0.86 [V] and the specified step-down correction value is 0.1 [V], the absolute value of the voltage difference ΔV is 0.04 [V], so the second step-down correction value is calculated as 0.06 [V] (= 0.1 - 0.04 [V]).

[0055] Then, in the next step S20, the power supply control unit 31 corrects the output voltage output from the power supply circuit 32 to the main control unit 20 in the power saving mode using the second step-down correction value. Specifically, the power supply control unit 31 steps down the output voltage to a voltage value obtained by subtracting the second step-down correction value from the detected voltage V1. In this case, the power supply control unit 31 outputs a correction command (correction signal) to the power supply circuit 32 to step down the current output voltage by the second step-down correction value. As a result, the power supply circuit 32 steps down the output voltage in accordance with the correction command.

[0056] For example, if the detected voltage V1 is 0.86 [V], the output voltage is stepped down to a voltage value of 0.8 [V] obtained by subtracting the first step-down correction value (0.06 [V]) from the detected voltage V1. Then, the series of processes ends.

[0057] If it is determined in step S18 that the detected voltage V1 is the same as the reference voltage V0, then in the next step S21, the power supply control unit 31 corrects the output voltage output from the power supply circuit 32 to the main control unit 20 in the power saving mode using the specified step-down correction value. Specifically, the power supply control unit 31 steps down the output voltage to a voltage value obtained by subtracting the specified step-down correction value from the detected voltage V1. In this case, the power supply control unit 31 outputs a correction command (correction signal) to the power supply circuit 32 to step down the current output voltage by the specified step-down correction value. As a result, the power supply circuit 32 steps down the output voltage in accordance with the correction command.

[0058] For example, if the detected voltage V1 is 0.9 [V], which is the same as the reference voltage V0, the output voltage is stepped down to a voltage value of 0.8 [V] obtained by subtracting the specified step-down correction value (0.1 [V]) from the detected voltage V1. Then, the series of processes ends.

[0059] As described above, in this embodiment, when the operation mode of the image forming apparatus 10 is switched to the power saving mode, the output voltage output from the power supply circuit 32 to the main control unit 20 is stepped down to a voltage value obtained by subtracting the correction values ​​(first step-down correction value, second step-down correction value) based on the specified step-down correction value from the reference voltage V0. Specifically, a voltage difference ΔV between the detected voltage V1 detected by the voltage detection unit 33 in the power saving mode and the reference voltage V0 is calculated, and the output voltage is corrected by the correction values ​​(first step-down correction value, second step-down correction value) calculated based on the voltage difference ΔV and the specified step-down correction value.

[0060] In this embodiment, when the detected voltage V1 is greater than the reference voltage V0, the first step-down correction value is calculated by adding the absolute value of the voltage difference ΔV to the specified step-down correction value, and the output voltage is stepped down to a voltage value obtained by subtracting the first step-down correction value from the reference voltage V0.

[0061] Furthermore, when the detected voltage V1 is smaller than the reference voltage V0, the second step-down correction value is calculated by subtracting the absolute value of the voltage difference ΔV from the specified step-down correction value, and the output voltage is stepped down to a voltage value obtained by subtracting the second step-down correction value from the reference voltage V0.

[0062] In this way, the output voltage output to the main control unit 20 is reduced during the power saving mode, so that the output voltage during the power saving mode is always adjusted to a stable voltage value regardless of the voltage value of the output voltage before the reduction.

[0063] Furthermore, if the output voltage before stepping down is higher than the reference voltage V0, the voltage is stepped down by the first step-down correction value more than when the voltage is simply stepped down by the specified step-down correction value, thereby further reducing the power consumption after stepping down.

[0064] 3, after the second step-down correction value is calculated in step S19, the power supply control unit 31 may determine whether the voltage value corrected by the second step-down correction value (corrected voltage value) is greater than a predetermined lower limit voltage (S191), and proceed to step S20 to step down the current output voltage by the second step-down correction value only if it is determined to be greater. Here, the lower limit voltage is a set value set to the lowest voltage at which the main control unit 20 can operate or a voltage value obtained by adding a tolerance to the minimum voltage, and is stored in the ROM of the power supply control unit 31.

[0065] Also, if it is determined in step S191 that the correction voltage value is equal to or less than the lower limit voltage, the power supply control unit 31 corrects the output voltage output from the power supply circuit 32 to the main control unit 20 in the power saving mode to the lower limit voltage (S192).

[0066] As a result, when the correction voltage value falls below the lower limit voltage, the output voltage is not corrected but is adjusted to the lower limit voltage, thereby preventing malfunction of the main control unit 20 due to insufficient voltage.

[0067] In the above embodiment, the image forming apparatus 10 is exemplified as an electrical device of the present invention, but the present invention can also be applied to various electrical devices other than the image forming apparatus 10.

[0068] [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.

[0069] <Appendix 1> a power supply voltage generating unit that outputs a voltage to an arithmetic processing unit that controls an operation processing unit included in the electrical device; a power supply control unit that, when the operating mode of the electrical equipment is switched to a power saving mode that suppresses the supply of power to the operation processing unit, reduces the output voltage output from the power supply voltage generation unit to a voltage value obtained by subtracting a correction value based on a predetermined specified step-down correction value from a reference operating voltage required when the operation processing unit is operating.

[0070] <Appendix 2> a voltage detection unit that detects the output voltage output from the power supply voltage generation unit to the arithmetic processing unit, The power supply control unit 2. The power supply device according to claim 1, wherein, when the operating mode of the electrical device is switched to the power saving mode, the power supply device calculates a voltage difference between the reference operating voltage and the detected voltage detected by the voltage detection unit in the power saving mode, and corrects the output voltage based on the voltage difference and the specified step-down correction value.

[0071] <Appendix 3> The power supply control unit When the detected voltage is greater than the reference operating voltage, a first step-down correction value is calculated by adding the absolute value of the voltage difference to the specified step-down correction value; 3. The power supply device according to claim 2, wherein the output voltage is stepped down to a voltage value obtained by subtracting the first step-down correction value from the reference operating voltage.

[0072] <Appendix 4> The power supply control unit When the detected voltage is smaller than the reference operating voltage, a second step-down correction value is calculated by subtracting the absolute value of the voltage difference from the specified step-down correction value; 4. The power supply device according to claim 2, wherein the output voltage is stepped down to a voltage value obtained by subtracting the second step-down correction value from the reference operating voltage.

[0073] <Appendix 5> 5. The power supply device according to claim 1, wherein the electrical device is an image processing device. [Explanation of symbols]

[0074] 10: Image forming device 20: Main control unit 30: Power supply unit 31: Power supply control unit 32: Power supply circuit 33: Voltage detection unit

Claims

1. a power supply voltage generating unit that outputs a voltage to an arithmetic processing unit that controls an operation processing unit included in the electrical device; a power supply control unit that, when the operating mode of the electrical equipment is switched to a power saving mode that suppresses the supply of power to the operation processing unit, reduces the output voltage output from the power supply voltage generation unit to a voltage value obtained by subtracting a correction value based on a predetermined specified step-down correction value from a reference operating voltage required when the operation processing unit is operating.

2. a voltage detection unit that detects the output voltage output from the power supply voltage generation unit to the arithmetic processing unit, The power supply control unit 2. The power supply device according to claim 1, wherein when the operating mode of the electrical device is switched to the power saving mode, a voltage difference between the reference operating voltage and a detected voltage detected by the voltage detection unit in the power saving mode is calculated, and the output voltage is corrected based on the voltage difference and the specified step-down correction value.

3. The power supply control unit When the detected voltage is greater than the reference operating voltage, a first step-down correction value is calculated by adding the absolute value of the voltage difference to the specified step-down correction value; 3. The power supply device according to claim 2, wherein the output voltage is stepped down to a voltage value obtained by subtracting the first step-down correction value from the reference operating voltage.

4. The power supply control unit When the detected voltage is smaller than the reference operating voltage, a second step-down correction value is calculated by subtracting the absolute value of the voltage difference from the specified step-down correction value; 4. The power supply device according to claim 2, wherein the output voltage is stepped down to a voltage value obtained by subtracting the second step-down correction value from the reference operating voltage.

5. The power supply device according to claim 1 , wherein the electrical device is an image processing device.

Images