JP5598067B2 - Charging apparatus and image forming apparatus using the same - Google Patents

Description

  The present invention relates to a charging device, an image forming apparatus using the same, a control method for the charging device, and a control program for the charging device, and in particular, a charging device including a rechargeable secondary battery, and image formation using the same. The present invention relates to a device, a charging device control method, and a charging device control program.

  For example, in an electronic apparatus such as an image forming apparatus (scanner function, facsimile function, copying function, printer function, data communication function, MFP (Multi Function Peripheral) having a server function, facsimile apparatus, copying machine, printer, etc.) Have a rechargeable secondary battery.

  A device provided with a secondary battery improves the efficiency of an AC / DC converter or the like (hereinafter sometimes referred to as a converter) and supplies power by the secondary battery during sleep of the device, thereby converting the converter. Can prevent power loss. The reduction in power loss contributes to the reduction of a value (for example, a TEC (Typical Electricity Consumption) value) indicating power consumption measured according to a certain standard. In recent years, the value indicating such power consumption is increasingly regarded as important in the evaluation of energy saving performance of electronic devices and the like.

  Patent Document 1 listed below discloses a notebook personal computer control device that limits a charging current for a secondary battery in accordance with current consumption of the device. This control device stores the power consumption in the operation mode as data in advance, and based on the data, uses the remaining amount of power used during the operation of the device for charging, thereby reducing the charging time of the secondary battery. Shorten.

Japanese Patent Laid-Open No. 11-55868

  By the way, in the apparatus described in Patent Document 1, the secondary battery is charged with a limited charging current that matches the surplus power. That is, a large current (for example, MAX (maximum) current) is supplied to the secondary battery in accordance with the amount of remaining power. However, when such a large current is output, the power supply efficiency may not increase.

  That is, in a device such as an MFP, for example, a fine load fluctuation always occurs during the operation of the device such as a printing operation and a copying operation. When load fluctuation occurs, the power supply efficiency of the power supply deteriorates and power loss may occur. As described above, when charging is performed when the apparatus is operating and the power supply efficiency is low and the power supply generates heat, the power loss of the power supply increases, and the energy saving performance of the apparatus may deteriorate.

  The present invention has been made to solve such problems, and can charge the secondary battery during the operation of the apparatus, and the power efficiency of the charging current is high and the power loss can be reduced. It is an object of the present invention to provide a charging device having high energy saving performance, an image forming apparatus using the charging device, a charging device control method, and a charging device control program.

In order to achieve the above object, according to one aspect of the present invention, a charging device that is used in an image forming apparatus and charges a secondary battery using power output from a power supply unit that supplies power for operating a load. The storage unit stores information on the power supply efficiency of the power supply unit, the power supply efficiency of the power supply unit is equal to or greater than a predetermined value according to the information on the power supply efficiency stored in the storage unit and the state of the image forming apparatus. An image forming apparatus includes: a current determining unit that determines a current value of a charging current of a secondary battery; and a current adjusting unit that adjusts a current value of a charging current of the secondary battery based on a determination result of the current determining unit. And at least a first operation state in which the secondary battery is operated and a second operation state in which the secondary battery is charged . when on the operational running, the field Performed in forming apparatus in accordance with the information on the amount of unfinished job, so that the charging of the secondary battery to the second operating state is completed is completed up to a predetermined amount, the determination of the current value.
Preferably, the power supply unit includes a plurality of converters that generate electric power to be output based on an input from an external power supply, and the current determination unit determines a current value so that each power supply efficiency of the plurality of converters is equal to or higher than a predetermined value. I do.
According to another aspect of the present invention, a charging device that is used in an image forming apparatus and charges a secondary battery using power output from a power supply that supplies power for operating a load is provided in the power supply A storage unit that stores information on power supply efficiency, and a power supply efficiency of the power supply unit that is greater than or equal to a predetermined value according to the information about the power supply efficiency stored in the storage unit and the state of the image forming apparatus. A current determining unit that determines a current value of the charging current; and a current adjusting unit that adjusts a current value of the charging current of the secondary battery based on a determination result of the current determining unit, the current determining unit together with the image forming apparatus with the determination of current value in accordance with the information about the presence or absence of optional devices for power from the power supply unit used to operate is supplied, the power supply unit, the first converter and to generate a power output based on an input from an external power source The second converter generates power used by the optional device when the optional device is attached to the image forming apparatus, and the first converter generates power used by the main body of the image forming apparatus. The charging device performs charging using the electric power generated by the first converter and the electric power generated by the second converter, and the current determination unit is configured such that when the optional device is not attached to the image forming apparatus, When the current value is determined so that the power efficiency of the first converter becomes equal to or higher than a predetermined value, and the optional device is attached to the image forming apparatus, the power efficiency of each of the first converter and the second converter is a predetermined value. The current value is determined as described above.

Preferably, the information regarding the power supply efficiency of the power supply unit includes information regarding the relationship between the current consumption of the image forming apparatus and the power supply efficiency of the power supply unit, and the current determination unit includes a value regarding the current consumption of the image forming apparatus , The current value is determined based on the information regarding the relationship between the current consumption of the image forming apparatus and the power supply efficiency of the power supply unit.

Preferably, the charging device further includes a switching unit that switches on / off the supply of the charging current to the secondary battery when the secondary battery is being charged, and the current determination unit is configured to switch the charging current by the switching unit. The current value is determined based on a value related to the current consumption of the image forming apparatus when the supply is turned off.

  Preferably, the charging device further includes a remaining amount detection unit that detects a remaining amount of the secondary battery, and the current determination unit determines a current value according to a detection result of the remaining amount detection unit.

  According to another aspect of the present invention, an image forming apparatus includes the charging device according to any of the above and a secondary battery charged by the charging device, and operates using electric power discharged from the secondary battery. Is possible.

  According to these inventions, the current value of the charging current of the secondary battery is adjusted so that the power supply efficiency becomes a predetermined value or more according to the situation regarding the power supply efficiency of the power supply unit and the state of the electronic device. Therefore, a secondary battery can be charged during the operation of the apparatus, and the power supply efficiency of the charging current is high, the power loss can be reduced, and a high energy-saving performance, an image forming apparatus using the same, and charging An apparatus control method and a charging apparatus control program can be provided.

1 is a perspective view showing an image forming apparatus in one embodiment of the present invention. 1 is a block diagram illustrating a configuration of an image forming apparatus. It is a graph which shows an example of a power supply efficiency curve. It is a flowchart which shows the control regarding charge of a secondary battery. It is a flowchart which shows the example of control regarding charge of a secondary battery when the option apparatus is attached. 5 is a graph showing an example of a change in load current during operation of the image forming apparatus detected by a current detection circuit. It is a graph which shows the relationship between the maximum value of charging current, and a battery remaining charge. 6 is a graph illustrating an example of a relationship between a remaining battery level and time and a relationship between a load current and time when a secondary battery is charged according to a situation related to a work amount of the image forming apparatus. It is a flowchart which shows the detection method of the load current during charge of a secondary battery. 6 is a graph showing a transition of current consumption during operation of the image forming apparatus.

  Hereinafter, an image forming apparatus according to one embodiment of the present invention will be described.

  The image forming apparatus is an MFP (Multi Function Peripheral) having a scanner function, a copying function, a printer function, a facsimile function, a data communication function, and a server function. In the scanner function, an image of a set original is read and stored in an HDD (Hard Disk Drive) or the like. In the copying function, it is further printed (printed) on paper or the like. In the function as a printer, when a print instruction is received from an external terminal such as a PC, printing is performed on a sheet based on the instruction. In the facsimile function, facsimile data is received from an external facsimile machine and stored in an HDD or the like. In the data communication function, data is transmitted / received to / from a connected external device. In the server function, a plurality of users can share data stored in the HDD or the like.

  The image forming apparatus includes a secondary battery and a charging device that charges the secondary battery. For example, in order to reduce a value indicating power consumption measured according to a certain standard such as a TEC (Typical Electricity Consumption) value, in an image forming apparatus, high efficiency of a converter or power supply by a secondary battery during sleep is performed. Has been done. The image forming apparatus is driven using power discharged from the secondary battery, for example, during operation in the sleep operation. The secondary battery is charged by the charging device during the operation of the image forming apparatus.

  For charging the secondary battery, a charging method is used in which the charging current is controlled so that the power supply efficiency is equal to or higher than a predetermined value, thereby preventing power loss in the converter. In other words, when the load current of the device fluctuates, the power supply efficiency is affected. In charging the secondary battery, the charge current is adjusted according to the change in the load current of the device, and the power supply efficiency during charging exceeds a predetermined value. And power loss is reduced.

  [Embodiment]

  FIG. 1 is a perspective view showing an image forming apparatus according to one embodiment of the present invention.

  [Configuration of Image Forming Apparatus 1]

  Referring to the figure, an image forming apparatus (an example of an electronic device) 1 includes a paper feed cassette 3, a paper discharge tray 5, an operation unit 11, a power supply unit 100, a control unit 200, a print unit 300, and a scan. Unit 400 and charging unit 500. The power supply unit 100, the control unit 200, the printing unit 300, the scanning unit 400, and the charging unit 500 are arranged inside the housing of the image forming apparatus 1. The charging unit 500 includes a secondary battery 510. Further, the image forming apparatus 1 can be attached with an optional device (an example of a load) 600 (shown in FIG. 2) that is linked to the print unit 300 or the like.

  The image forming apparatus 1 has three paper feed cassettes 3 (paper feed cassettes 3a, 3b, 3c). The paper feed cassette 3 is disposed in the lower part of the image forming apparatus 1 so as to be detachable from the housing of the image forming apparatus 1. For example, different paper sizes (B5 size, A4 size, A3 size, etc.) and papers in different states are loaded in each paper feed cassette 3. The paper loaded in each paper feed cassette 3 is fed from the paper feed cassette 3 one by one at the time of printing and sent to the printing unit 300. Note that the number of paper feed cassettes 3 is not limited to three, and may be more or less.

  The paper discharge tray 5 is disposed above the portion of the housing of the image forming apparatus 1 where the print unit 300 is stored and below the portion where the scan unit 400 is disposed. The paper on which the image is formed by the printing unit 300 is discharged from the inside of the housing to the paper discharge tray 5.

  The operation unit 11 is disposed on the upper front side of the image forming apparatus 1. The operation unit 11 includes a plurality of operation buttons 11a that can be pressed by the user. A display panel 13 is disposed on the operation unit 11. The display panel 13 is, for example, an LCD (Liquid Crystal Display) provided with a touch panel. The display panel 13 displays a guidance screen for the user or displays an operation button to accept a touch operation from the user.

  The power supply unit 100 is provided inside the housing of the image forming apparatus 1. The power supply unit 100 includes an AC-DC converter. The power source unit 100 is connected to a commercial power source (an example of an external power source), and supplies power to each unit of the image forming apparatus 1 such as the control unit 200, the print unit 300, the scan unit 400, and the charging unit 500 based on the commercial power source. Supply.

  The scanning unit 400 is disposed on the upper part of the housing of the image forming apparatus 1. The scanning unit 400 includes an ADF (Auto Document Feeder) 410. The scanning unit 400 performs the above-described scanner function. The scanning unit 400 scans a document placed on a transparent document table with an image sensor such as a contact image sensor, and reads it as image data. The scanning unit 400 reads the image data by a contact image sensor or the like while sequentially taking in a plurality of documents set on the document tray by the ADF 410.

  FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus 1.

  Referring to the figure, power supply unit (main power supply) 100 includes a relay (RY) 101, a first converter 111, a first current detection circuit 113, a second converter 121, and a second current detection circuit 123. Have.

  The relay 101 is connected to a commercial power supply outside the image forming apparatus 1.

  Each of the first converter 111 and the second converter 121 is connected to the relay 101. The first converter 111 and the second converter 121 convert AC power from a commercial power source input via the relay 101 into DC power.

  The first current detection circuit 113 is connected to the first converter 111 and detects the direct current output from the first converter 111. The second current detection circuit 123 is connected to the second converter 121 and detects a direct current output from the second converter 121. That is, the first current detection circuit 113 and the second current detection circuit 123 detect a value related to the current consumption of the image forming apparatus 1. The first current detection circuit 113 and the second current detection circuit 123 each output a load current detection signal according to the detected magnitude of the direct current. The load current detection signals output from the first current detection circuit 113 and the second current detection circuit 123 are input to the control unit (main control unit) 200.

  The control unit 200 includes a CPU 201, a ROM 203, a RAM 205, a data storage unit 211, and an image processing unit 213. The controller 200 is driven by being supplied with DC power output from the first converter 111 via the first current detection circuit 113.

  The control unit 200 supplies power to the operation unit 11 and the I / F (interface) unit 17 to operate them. The control unit 200 can communicate with the operation unit 11 and the I / F unit 17 and controls each unit of the image forming apparatus 1 in accordance with signals and information transmitted from the operation unit 11 and the I / F unit 17. .

  The I / F unit 17 communicates with an external device (for example, a personal computer or a server on the Internet) via a LAN (Local Area Network) by a communication protocol such as TCP / IP according to an instruction from the control unit 200. Send and receive data between.

  Here, the display panel 13 of the operation unit 11 is controlled by the control unit 200 to perform display. When the operation button 11a or the display panel 13 is operated by the user, the operation unit 11 transmits an operation signal or a predetermined command corresponding to the operation to the control unit 200. That is, the user can cause the image forming apparatus 1 to execute various operations by operating the operation unit 11.

  The CPU 201 communicates with the ROM 203, the RAM 205, and the like to execute various processes. The ROM 203 is a flash memory, for example. The RAM 205 is used as a working memory when the CPU 201 executes processing. The CPU 201 performs various controls of the image forming apparatus 1 by executing a control program stored in the ROM 203 or the data storage unit 211, for example.

  The data storage unit 211 is, for example, an HDD (Hard Disk Drive). The data storage unit 211 receives print data for forming an image in the print unit 300, various setting information of the image forming apparatus 1, image data read by the scan unit 400, and the I / F unit 17. The image data acquired from the connected external device is stored. The data storage unit 211 may be an SSD (Solid State Drive) or the like.

  The image processing unit 213 is acquired from, for example, image data formed on a sheet by the printing unit 300, image data read by the scanning unit 400, or an external device connected via the I / F unit 17. Various image processing is performed on the image data and the like under the control of the CPU 201.

  The control unit 200 transmits a control signal to the relay 101 and controls the operation of the relay 101. That is, the control unit 200 controls the input of AC power to the image forming apparatus 1.

  For example, the image forming apparatus 1 operates in one of three operation states under the control of the control unit 200. The operating state includes a driving state for performing a printing operation, a standby state in which each part of the apparatus is prepared for the printing operation, and a sleep state for waiting until an execution instruction for the printing operation is performed. When the printing operation or the like is not performed, the control unit 200 puts the image forming apparatus 1 into a sleep state, thereby reducing power consumed by the image forming apparatus 1 and saving energy in the image forming apparatus 1.

  When the execution instruction of the printing operation is performed while the image forming apparatus 1 is in the sleep state, the operation state of the image forming apparatus 1 changes from the sleep state to the driving state, and a job such as a print job is executed based on the execution instruction. Executed. When the job is executed, the operation state of the image forming apparatus 1 changes from the driving state to the standby state. When in the standby state, for example, if there is no execution instruction such as a printing operation within a predetermined period, the operation state of the image forming apparatus 1 changes from the standby state to the sleep state, and power consumption is reduced.

  The print unit 300 includes a motor (an example of a load) 301, a fan (an example of a load) 303, a sensor (an example of a load) 305, another load unit (a secondary load; an example of a load) 307, and a fixing heater ( An example of a load) 309 and an engine unit 320 are included. The printing unit 300 forms an image on a sheet conveyed from the sheet feeding cassette 3 to the inside of the image forming apparatus 1 by, for example, electrophotography.

  The motor 301 drives a photosensitive member and a developing device for forming a toner image and a roller provided for conveying paper. The fan 303 discharges air in the apparatus to the outside so that heat does not accumulate inside the image forming apparatus 1 and introduces outside air into the apparatus. The sensor 305 is a paper sensor provided on the paper transport path, a temperature sensor that detects the temperature of the fixing heater 309, or the like. The other load unit 307 includes, for example, a light source that emits light for exposing the photosensitive member. The fixing heater 309 is driven at the time of printing 300 and generates heat for fixing the toner image formed on the paper to the paper.

  The engine unit 320 includes a CPU 321, a ROM 323, a RAM 325, and an ASIC (Application-Specific Integrated Circuit) 327. Further, the engine unit 320 includes a plurality of drive circuits (each drive circuit) 330 each having an ASIC 331. The CPU 321 of the engine unit 320 communicates with the control unit 200 such as transmitting a drive status signal or the like to the control unit 200. The CPU 321 drives each drive circuit 330 under the control of the control unit 200 to execute image formation on a sheet. The CPU 321 drives the motor 301, the fan 303, the sensor 305, the other load unit 307, and the like to form a toner image on the paper by an electrophotographic method. Further, the CPU 321 uses the heat of the fixing heater 309 to fix the toner image on the paper.

  The engine unit 320 is driven by being supplied with DC power output from the first converter 111 via the first current detection circuit 113. The motor 301, the fan 303, the sensor 305, and the other load unit 307 are driven when DC power is supplied from the engine unit 320. On the other hand, the fixing heater 309 operates using AC power supplied from the relay 101 of the power supply unit 100.

  The charging unit 500 includes a secondary battery 510, a current adjustment circuit (an example of a current adjustment unit) 520, a charge control circuit (an example of a current determination unit, an example of a switching unit) 530, and a relay (RY) 570. doing. The charging unit 500 functions as a charging device that charges the secondary battery 510 together with the power supply unit 100 and the control unit 200 inside the image forming apparatus 1. The secondary battery 510 is supplied with power from the power supply unit 100 and is charged by the charging unit 500 under the control of the control unit 200.

  The secondary battery 510 is, for example, a lithium ion battery. The secondary battery 510 may be another type of secondary battery such as a lead storage battery.

  The current adjustment circuit 520 charges the secondary battery 510 by adjusting the current value of the direct current output from the power supply unit 100 and supplying it to the secondary battery 510. DC power output from the first converter 111 via the first current detection circuit 113 and DC power output from the second converter 121 via the second current detection circuit 123 are input to the current adjustment circuit 520. .

  The charge control circuit 530 includes a CPU 531, a ROM (an example of a storage unit) 533, a RAM 535, and a battery remaining amount detection circuit (an example of a remaining amount detection unit) 537. The ROM 533 is, for example, a flash memory. The ROM 533 stores a control program 533a. The CPU 531 reads out and executes the control program 533a to execute various operations related to charging.

  The load current signal output from the control unit 200 is input to the charging control circuit 530. The load current signal is a signal calculated by the control unit 200 based on a driving status signal indicating the driving status of the engine unit 320.

  The CPU 531 determines the direct current output from the current adjustment circuit 520, that is, the current value of the charging current of the secondary battery 510, based on the input load current signal. Then, the CPU 531 controls the charging operation of the secondary battery 510 by the current adjustment circuit 520 by outputting a charging current control signal to the current adjustment circuit 520 based on the determined current value. The current adjustment circuit 520 adjusts the current value of the charging current of the secondary battery 510 based on the charging current control signal output from the charging control circuit 530, that is, the determination result of the current value of the direct current of the charging control circuit 530.

  DC power discharged from the secondary battery 510 is input to the charging control circuit 530. The battery remaining amount detection circuit 537 detects the remaining amount of the secondary battery 510 based on the input DC power or the like.

  Charging control circuit 530 can supply DC power of secondary battery 510 to control unit 200 via relay 570. The control unit 200 controls the power supply from the charging control circuit 530 to the control unit 200 via the relay 570 by transmitting a signal to the relay 570.

  Thus, when the power from the secondary battery is supplied, the control unit 200 can operate based on the power of the secondary battery 510. At this time, the control unit 200 can operate in a state where the input of AC power to the image forming apparatus 1 is interrupted by controlling the relay 101.

  The option device 600 is, for example, a document feeder (DF) or a finisher (FNS). The optional device 600 is additionally attached to the main body of the image forming apparatus 1 and is used together with the image forming apparatus 1. As a result, various functions can be added to the image forming apparatus 1. For example, when a finisher is used as the optional apparatus 600, it is possible to output a sheet of paper on which an image has been formed by the print unit 300, several pages at a time by the finisher, by using a stapler, and as a booklet.

  The optional device 600 operates by being supplied with DC power output from the second converter 121 via the second current detection circuit 123. Optional device 600 communicates with control unit 200 and is driven under the control of control unit 200.

  When the option device 600 is attached to the image forming apparatus 1, an option detection signal is output from the option device 600 to the control unit 200. When this option detection signal is input, the control unit 200 can identify the presence or absence of an optional device attached to the image forming apparatus 1 and identify the optional device. That is, the control unit 200 functions as an optional device detection unit that detects the presence or absence of the optional device 600, for example. The charging control circuit 530 of the charging unit 500 can acquire information related to the presence / absence of the optional device 600 and the identification of the optional device 600 from the control unit 200.

  [Description on Charging of Secondary Battery 510]

  By the way, the image forming apparatus 1 is driven using the electric power discharged from the secondary battery 510, for example, during the operation in the sleep state. At this time, power is not supplied from the power supply unit 100 to each part of the image forming apparatus 1, and the image forming apparatus 1 saves power. When the image forming apparatus 1 is in the standby state or drive state from the sleep state, that is, when the image forming apparatus 1 is in operation, power is supplied from the power supply unit 100. At this time, the secondary battery 510 is charged by the charging unit 500. The direct current, that is, the consumption current, output from the converters 111 and 121 of the power supply unit 100 during the operation of the image forming apparatus 1 includes a current for a load current and a current for a charging current.

  For charging secondary battery 510, a charging method is used in which the charging current is controlled so that the power efficiency of converters 111 and 121 of power supply unit 100 is equal to or higher than a predetermined value. This prevents power loss in the converter. When the DC current consumption of the image forming apparatus 1 fluctuates, the power efficiency of the converters 111 and 121 is affected. That is, when the load current of the image forming apparatus 1 fluctuates, the power supply efficiency is affected. When charging the secondary battery 510, the charging current linearly changes in accordance with the load current of the image forming apparatus 1, and the power efficiency during charging is maintained at a predetermined value or more, so that power loss in the converters 111 and 121 is lost. Is reduced.

  In the present embodiment, the ROM 533 of the charging control circuit 530 stores information regarding the power supply efficiency of the power supply unit 100. The information related to the power supply efficiency of the power supply unit 100 includes information related to the relationship between the current consumption for the DC power of the image forming apparatus 1 and the power supply efficiency of the power supply unit 100. This information is stored in the ROM 533 as a power efficiency curve, for example.

  FIG. 3 is a graph showing an example of a power efficiency curve.

  Referring to the figure, the power efficiency curve shows the relationship between the current consumption for the DC power of image forming apparatus 1 and the power efficiency of converters 111 and 121 of power supply unit 100. Generally, in a converter, when current consumption changes, power supply efficiency changes under the influence. That is, referring to the figure, as the current consumption increases from 0 A, the power supply efficiency increases from about 10%. The power supply efficiency is about 80% or more when the current consumption is between about 2 A and about 6 A. The power supply efficiency is highest when the current consumption is between 2A and 6A. When the current consumption exceeds about 6 A, the power efficiency becomes less than 80% and decreases.

  In the present embodiment, CPU 531 of charge control circuit 530 calculates (determines) the current value of the charging current of secondary battery 510 so that the power efficiency of power supply unit 100 is equal to or greater than a predetermined value. For example, the CPU 531 determines the value of the charging current in consideration of the load current, and thereby sets the value of the current consumption to a value such that the power supply efficiency is always 80% or more. Details of the method for determining the value of the charging current will be described later.

  The charging control circuit 530 charges the secondary battery 510 so that the power supply efficiency of the power supply unit 100 becomes a predetermined value or more according to the information related to the power supply efficiency as described above and the information related to the state of the image forming apparatus 1. Determine the current value of the current. Information regarding the state of the image forming apparatus 1 includes information on the current consumption current of the image forming apparatus 1.

  First, a control flow relating to charging of the secondary battery 510 when the optional device 600 is not attached will be described. At this time, the second converter 121 does not contribute to current consumption. Therefore, the secondary battery 510 is charged in view of the power efficiency of the first converter 111.

  FIG. 4 is a flowchart showing control related to charging of the secondary battery 510.

  Referring to the figure, in step S101, CPU 201 of control unit 200 calculates a load current based on a driving status signal indicating the driving status of engine unit 320. A load current signal is output based on the calculated load current.

  In step S103, the CPU 531 of the charge control circuit 530 determines whether the power efficiency of the first converter 111 is equal to or higher than a predetermined value (for example, 80%) based on the load current signal output from the control unit 200. .

  If the power efficiency is greater than or equal to the predetermined value in step S103, the CPU 531 performs control to turn off the charging current in step S105. For example, the CPU 531 determines the current value of the charging current to be zero. The current adjustment circuit 520 receives the determination of the charging current and adjusts the current value of the charging current to zero. That is, the charging current is turned off by the current adjustment circuit 520.

  On the other hand, if the power efficiency is not equal to or higher than the predetermined value in step S103, the CPU 531 performs a charging current setting process in step S107. For example, the current value of the charging current is set (determined) in view of the current load current of the power supply unit 100 so that the current consumption is in the range of 2A to 6A where the power supply efficiency is 80% or more. When the current value of the charging current is determined by the CPU 531, a charging current control signal is output to the current adjustment circuit 520.

  In step S109, the current adjustment circuit 520 receives the charging current control signal and adjusts the current value of the charging current of the secondary battery 510 according to the received charging current control signal. Thereby, the charging current of the secondary battery 510 is turned on, and the charging current having the determined current value is supplied to the secondary battery 510.

  Next, a flow of control related to charging of the secondary battery 510 when the optional device 600 is attached will be described. At this time, the power output from the second converter 121 is consumed by the optional device 600. Therefore, the secondary battery 510 is charged in view of the power efficiency of each of the first converter 111 and the second converter 121.

  FIG. 5 is a flowchart illustrating a control example related to charging of the secondary battery 510 when the optional device 600 is attached.

  For each of the first converter 111 and the second converter 121, processing for determining the charging current is performed as described above.

  Referring to the figure, first, in step S201, when the CPU 201 of the control unit 200 recognizes the optional device 600, the CPU 201 detects the load current detection signal transmitted from both the first current detection circuit 113 and the second current detection circuit 123. Based on this, the load current is calculated. That is, the main body load current on the first converter 111 side such as the printing unit 300 and the optional load current on the second converter 121 side consumed by the optional device 600 are calculated.

  The processing in steps S203 to S209 is performed for each of the first converter 111 side and the second converter 121 side in the same manner as the processing in steps S103 to S109 in FIG. 4 described above. That is, based on the load current for each converter 111, 121, when it is determined that the power efficiency is not equal to or greater than a predetermined value, the CPU 531 causes the power efficiency for each converter 111, 121 to be equal to or greater than a predetermined value. The charging current of the secondary battery 510 is controlled.

  [Method of determining charging current]

  The charge control circuit 530 determines the current value based on the detection results of the first current detection circuit 113 and the second current detection circuit 123 and information on the relationship between the current consumption of the image forming apparatus 1 and the power supply efficiency of the power supply unit 100. Make a decision.

  FIG. 6 is a graph showing a variation example of the load current during the operation of the image forming apparatus 1 detected by the current detection circuit 113.

  Referring to the figure, the value of the load current greatly fluctuates during the operation of image forming apparatus 1 (shown surrounded by a broken line in the figure).

  Here, it is assumed that the optional device 600 is not attached and the current value of the charging current is controlled so that the power supply efficiency is 80% or more. If the output current (consumption current) of the first converter 111 is 2A to 6A, the power supply efficiency is 80%. Especially when the load current is lower than 2A (indicated by a dashed line in the figure). The charging current is controlled so that the output current of one converter 111 falls within the range of 2A to 6A.

  For example, when the load current of the first converter 111 is 0.5 A, the CPU 531 determines that the charging current is 1.5 A, and the charging current is adjusted to 1.5 A by the current adjustment circuit 520, whereby the first converter The output current of 111 is 2A. Note that the charging current can be arbitrarily selected within a range in which the output current of the first converter 111 falls within this range. As the value of the charging current, the maximum value may be selected so that the output range is within the above range, so that the charging time can be shortened.

  In the present embodiment, the charging control circuit 530 includes a detection result of the battery remaining amount detection circuit 537, a detection result of the presence or absence of the optional device 600 by the control unit 200, and the secondary battery 510 detected by the battery remaining amount detection circuit 537. The current value is determined so that the power efficiency of each of the two converters 111 and 121 is equal to or greater than a predetermined value in accordance with the information regarding the remaining amount and the work amount of the image forming apparatus 1.

  Information regarding the work amount of the image forming apparatus 1 includes information on a print job executed in the image forming apparatus 1 and information on a reading job using the scanning unit 400. For example, the control unit 200 periodically acquires information related to the amount of work by detecting an incomplete print job or the like in the image forming apparatus 1.

  Here, the charge control circuit 530 can ensure the remaining battery level necessary for returning from the sleep state to the operating state according to the remaining amount of the secondary battery 510 detected by the remaining battery level detection circuit 537. Thus, the maximum value (maximum charging current) of the determinable charging current is set. The charging control circuit 530 determines the value of the charging current so that the maximum charging current set in this way is not exceeded and the power supply efficiency of the power supply unit 100 becomes a predetermined value (for example, 80%) or more. .

  FIG. 7 is a graph showing the relationship between the maximum value of the charging current and the remaining battery level.

  Referring to the figure, the maximum charging current is set to a relatively large substantially constant value (for example, 6A) when the remaining battery capacity is smaller than a first predetermined value (for example, 60%). Further, the maximum charging current is set to a relatively small and substantially constant value (for example, 2A) when the remaining battery level is larger than a second predetermined value (for example, 80%) that is larger than the first predetermined value. When the remaining battery level is larger than the first predetermined value and smaller than the second predetermined value (for example, 60 to 80%), the maximum charging current is set to gradually decrease as the remaining battery level increases. The

  For example, when the remaining battery level is 40%, the maximum charging current is set to about 6A. At this time, the charging control circuit 530 determines the charging current so that the charging current does not exceed 6A. The value of the charging current is determined according to the load current so as to satisfy the formula of (charging current) = 6A− (load current). That is, the value of the charging current is determined to be a value obtained by subtracting the value of the load current from the maximum charging current. Thereby, the value of the charging current becomes the maximum value within a determinable range, and the secondary battery 510 is quickly charged.

  FIG. 8 is a graph showing an example of the relationship between the remaining battery level and time and the relationship between the load current and time when the secondary battery 510 is charged according to the situation regarding the work amount of the image forming apparatus 1. .

  When the control unit 200 or the like is driven using the electric power discharged from the secondary battery 510 in the sleep state, it is necessary to complete the necessary amount of charging before the standby state ends. That is, when the secondary battery 510 is discharged in the sleep state, the secondary battery 510 is sufficiently charged while in the operation state or the standby state in which power is supplied from the power supply unit 100. Need to be.

  In the figure, “JOB” indicates a period when the job is executed, that is, the period in which the image forming apparatus 1 is in an operating state, and “STB” indicates a period in which the image forming apparatus 1 is in a standby state. Referring to the figure, for example, it is assumed that image forming apparatus 1 is provided in an office and image forming apparatus 1 is not used during a lunch break from 12:00 to 13:00. In this case, it is necessary to continue supplying power from the secondary battery 510 in the sleep state for one hour. That is, the discharge state of the secondary battery 510 needs to be maintained for 1 hour. In such a case, it is necessary to charge the required amount before the 12:00 entering the lunch break period, during the execution of the last job and during the subsequent standby (during the operation state and the subsequent standby state).

  In the example shown in the figure, when the maximum charging current is set to 5A during the execution of the last job and the subsequent standby (when the charging current MAX5A mode is set), then during the lunch break period. The power that needs to be supplied from the secondary battery 510 in the sleep state is insufficient (indicated by a thin line in the figure). Therefore, in this case, the maximum charging current is set to 6A (charging current MAX6A mode is set). Thereby, as shown by a broken line in the figure, the secondary battery 510 is charged more rapidly than in the case where the charging current MAX5A mode shown by the alternate long and short dash line is set. Such setting of the maximum charging current is performed, for example, when the charge control circuit 530 communicates with the control unit 200 or the remaining battery level of the secondary battery 510 is detected by the remaining battery level detection circuit 537. The secondary battery 510 may be charged so that the remaining amount becomes 100% before entering the sleep state. In addition, when the amount of power expected to be consumed in the sleep state is limited, the secondary battery 510 is secured so that the remaining amount can be secured before the sleep state is entered. May be charged.

  Here, when the amount of jobs to be executed is large, the maximum charging current may be set so that charging is completed at the time when the standby state is completed. By performing charging for as long as possible during execution of a job and during standby after that, it becomes easy to adjust power supply efficiency by charging current, and power loss can be reduced.

  [Load current detection method]

  The first current detection circuit 113 and the second current detection circuit 123 detect a value related to the current consumption of the image forming apparatus 1 when the supply of the charging current to the secondary battery 510 by the current adjustment circuit 520 is turned off. . That is, when the secondary battery 510 is being charged, the charging control circuit 530 controls the current adjustment circuit 520 to switch on / off the supply of the charging current to the secondary battery 510 and to the secondary battery 510. To turn off the charging current supply. At this time, the control unit 200 calculates a current consumption value of the image forming apparatus 1 based on the load current detection signals output from the first current detection circuit 113 and the second current detection circuit 123. Note that the calculated values are the current consumption value output from the first converter 111 and consumed, and the current consumption value output from the second converter 121 and consumed.

  FIG. 9 is a flowchart showing a method for detecting a load current while the secondary battery 510 is being charged.

  In step S301, the charging control circuit 530 turns off the charging current of the secondary battery 510. Note that the charging control circuit 530 may turn off the charging current of the secondary battery 510 by determining the charging current to be zero, or the current adjustment circuit 520 so that the charging current is not supplied to the secondary battery 510. The charging current of the secondary battery 510 may be turned off by controlling.

  In step S303, the control unit 200 detects the load current based on the load current signal from the current detection circuits 113 and 123.

  In step S305, the charging control circuit 530 performs a charging current setting process based on the load current detected by the control unit 200. The charging current setting process is performed in the same manner as described above.

  In step S307, the current adjustment circuit 520 adjusts the charging current so that the secondary battery 510 is charged with the charging current having the value determined by the charging current setting process by the charging control circuit 530. Thereby, the charging current is turned on.

  FIG. 10 is a graph showing a change in current consumption during the operation of the image forming apparatus 1.

  Referring to the figure, the detection of the load current performed by turning off the supply of the charging current as described above is performed during a current detection period (for example, for 1 msec) periodically provided during the operation of the image forming apparatus 1. Is called.

  For example, when the current detection period is reached at time t1, the charging current is turned off during that time, and the consumption current is only the load current. At this time, if the current consumption is 0.2 A, it is detected that the load current is 0.2 A. For example, when the power consumption efficiency is equal to or higher than a predetermined value when the current consumption is 2 A, the charging control circuit 530 charges the charging current to 1 so that the current consumption becomes 2 A by charging the secondary battery 510. .8A is determined. Thus, after the elapse of the current detection period from time t1, 1.8 A is supplied as the charging current from the current adjustment circuit 520 to the secondary battery 510 until time t2 when the next current detection period starts, and charging is performed. Is called. When the current detection period is reached at time t2, the charging current is turned off again, the load current is detected (1.5A), and the charging current is determined to be 0.5A accordingly. When the current detection period elapses, the secondary battery 510 is charged with a charging current of 0.5 A. Thereafter, each time the current detection time starts at times t3, t4,..., The load current is similarly detected, and the subsequent charging current of the secondary battery 510 is adjusted.

  In the power supply unit 100, if a current detection circuit for detecting a charge current and a current detection circuit for detecting a load current are provided for one converter, the load current can be easily detected and the adjustment of the charge current is easy. Can be done. However, in this case, there is a problem that the number of current detection circuits increases and the manufacturing cost increases. In the present embodiment, the charge current is controlled as described above, and the load current can be detected by one current detection circuit provided for one converter, so that the manufacturing cost can be reduced. it can.

  [Effects of the embodiment]

  In the image forming apparatus configured as described above, the charging current at which the power efficiency becomes a predetermined value or more is determined according to the detection result of the current consumption of the power supply unit, that is, the operating state of the image forming apparatus. The output currents of the converter and the second converter are controlled so that the power supply efficiency is always a predetermined value or more. Therefore, it is possible to reduce power loss due to a decrease in power supply efficiency in the first converter and the second converter. By reducing the power loss, it is possible to reduce a value (for example, a TEC value) indicating a power consumption amount measured according to a certain standard, which is often regarded as important in the evaluation of energy saving performance.

  Since the charging current is controlled in each of the two converters, the power loss of the power supply unit can be reliably reduced.

  During the operation of the image forming apparatus, the charging current is repeatedly turned on and off, and the consumption current is detected when the charging current is turned off, whereby the load current is detected. Since the charging current at which the power supply efficiency is equal to or higher than the predetermined value is determined based on the load current, it is possible to more reliably reduce the power loss of the power supply unit.

  Further, the charging current is determined in a state where the upper limit of the charging current is set based on the remaining amount of the secondary battery, the amount of jobs to be executed, that is, the amount of work, and the state of the image forming apparatus. Therefore, the charging time of the secondary battery is shortened and overcharging is prevented. By changing the setting value of the charging current according to the remaining amount of the secondary battery, the charging time is shortened and overcharging is prevented.

  Even when there is a change in power consumption in the optional device of the image forming apparatus, a charging current at which the power efficiency becomes a predetermined value or more is determined from the current consumption in the entire apparatus, and the charging current is always controlled even during operation. You can do so. Thereby, the power loss of a power supply part can be reduced. The installation combination of the optional devices may be detected by the control unit, and the charging current may be determined by the charging control circuit accordingly.

  [Others]

  The number of converters that generate electric power to be output based on an input from an external power source is not limited to two, and may be one or three or more. The charging current may be determined so that the power efficiency of each of the plurality of converters is equal to or higher than a predetermined value.

  The storage unit that stores information regarding the power supply efficiency of the power supply unit may be, for example, a ROM or a data storage unit of the control unit. At this time, the control unit may determine the current value of the charging current based on the information and information on the current consumption.

  The image forming apparatus may be any one of a monochrome / color copying machine, a printer, a facsimile machine, and a complex machine (MFP) thereof. Further, the image forming method is not limited to the one that forms an image by an electrophotographic method, and may be one that forms an image by a so-called inkjet method, for example.

  In addition, the device in which the charging device is used is not limited to the image forming apparatus. In various electronic devices that can be driven by a secondary battery under specific circumstances, by using the above-described charging device, it is possible to reduce power loss of a power supply unit that supplies power for driving the electronic device. it can.

  Further, the processing in the above-described embodiment may be performed by software or by using a hardware circuit.

  In addition, a program for executing the processing in the above-described embodiment can be provided, and the program is recorded on a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, and a memory card and provided to the user. You may decide to do it. The program may be downloaded to the apparatus via a communication line such as the Internet. The processing described in the text in the above flowchart is executed by the CPU according to the program.

  In addition, it should be thought that the said embodiment is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 Image forming apparatus (an example of an electronic device, an example of a charging device)
DESCRIPTION OF SYMBOLS 100 Power supply part 111 1st converter 113 1st current detection circuit 121 2nd converter 123 2nd current detection circuit 200 Control part 201 CPU
203 ROM
301 Motor (an example of load)
303 fans (example of load)
305 Sensor (an example of load)
307 Other load section (an example of load)
500 Charging Unit 510 Secondary Battery 520 Current Adjustment Circuit (Example of Current Adjustment Unit)
530 Charge control circuit (an example of a current determination unit, an example of a switching unit)
531 CPU
533 ROM (an example of a storage unit)
533a Control program 537 Battery remaining amount detection circuit (an example of remaining amount detection unit)
600 Optional equipment

Claims (7)

A charging device that is used in an image forming apparatus and charges a secondary battery using power output from a power supply unit that supplies power for operating a load.
A storage unit for storing information on power supply efficiency of the power supply unit;
The current value of the charging current of the secondary battery is determined so that the power supply efficiency of the power supply unit is equal to or higher than a predetermined value according to the information regarding the power supply efficiency stored in the storage unit and the state of the image forming apparatus. A current determining unit to
A current adjusting unit that adjusts a current value of a charging current of the secondary battery based on a determination result of the current determining unit;
The image forming apparatus is operable in at least a first operation state that operates using the power of the secondary battery and a second operation state in which the secondary battery is charged.
The current decision unit, when the image forming apparatus is operating in the second operating state, the executed in the image forming apparatus, in accordance with the information on the amount of uncompleted job, the second operation A charging device that determines the current value so that the charging of the secondary battery is completed to a predetermined amount before the state ends . The power supply unit includes a plurality of converters that generate electric power to be output based on an input from an external power supply,
The charging device according to claim 1 , wherein the current determination unit determines the current value so that power efficiency of each of the plurality of converters is equal to or greater than a predetermined value. A charging device that is used in an image forming apparatus and charges a secondary battery using power output from a power supply unit that supplies power for operating a load.
A storage unit for storing information on power supply efficiency of the power supply unit;
The current value of the charging current of the secondary battery is determined so that the power supply efficiency of the power supply unit is equal to or higher than a predetermined value according to the information regarding the power supply efficiency stored in the storage unit and the state of the image forming apparatus. A current determining unit to
A current adjusting unit that adjusts a current value of a charging current of the secondary battery based on a determination result of the current determining unit;
The current determination unit determines the current value according to information on the presence or absence of an optional device that is used together with the image forming apparatus and operates with power supplied from the power supply unit .
The power supply unit includes a first converter and a second converter that generate electric power to be output based on an input from an external power supply,
The second converter generates electric power used by the optional device when the optional device is attached to the image forming apparatus,
The first converter generates electric power used in the image forming apparatus main body,
The charging device performs the charging using the power generated by the first converter and the power generated by the second converter,
The current determination unit includes:
When the optional device is not attached to the image forming apparatus, the current value is determined so that the power efficiency of the first converter is equal to or higher than a predetermined value.
A charging device that determines the current value so that power efficiency of each of the first converter and the second converter is equal to or higher than a predetermined value when the optional device is attached to the image forming apparatus. The information related to the power supply efficiency of the power supply unit includes information related to the relationship between the current consumption of the image forming apparatus and the power supply efficiency of the power supply unit,
The current determination unit determines the current value based on a value related to current consumption of the image forming apparatus and information related to a relationship between current consumption of the image forming apparatus and power supply efficiency of the power supply unit. Item 4. The charging device according to any one of Items 1 to 3 . A switching unit that switches on / off the supply of charging current to the secondary battery when the secondary battery is being charged;
The current determination unit performs determination of the said current value based on the value relating to the current consumption of the image forming apparatus at the time when the supply of the charging current by the switching unit is turned off, any one of claims 1 to 4 The charging device described in 1. A remaining amount detecting unit for detecting the remaining amount of the secondary battery;
The current determination unit performs determination of the current value according to the ink amount detection portion of the detection result, the charging device according to any one of claims 1 to 5. The charging device according to any one of claims 1 to 6 ,
A secondary battery charged by the charging device,
An image forming apparatus operable with electric power discharged from the secondary battery.