JP5219585B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic process, and more particularly, to an image forming apparatus including an auxiliary power source that can be charged as a driving power source for a load.

  In an image forming apparatus using an electrophotographic process such as a copying machine, an electrostatic printer, or a facsimile, an electrostatic latent image obtained by irradiating light onto a photosensitive drum is used as a developer (hereinafter referred to as “toner”). The image is formed by developing at. Then, after the toner image is transferred onto the transfer paper, the transfer paper carrying the unfixed toner image is conveyed to the fixing device.

  The fixing device includes a heating roller formed by forming a releasable resin film on the surface of a cylindrical metal core, and a pressure roller which is in pressure contact with the elastic roller layer on the surface. In the fixing device, the surface of the heating roller reaches a predetermined fixing temperature, and the toner image surface is a transfer roller carrying an unfixed toner image in the nip portion between the heating roller and the pressure roller. Pass the paper so that it touches the. Then, the toner image is fused and fixed to the transfer paper surface by heat and pressure. Such a fixing device (heat roller fixing device) is widely used in image forming apparatuses.

  In the heat roller fixing device, since it is necessary to raise the heating roller to a predetermined fixing temperature within a predetermined start-up time, a large amount of heat, that is, electric power is required. In recent years, a method has been adopted to reduce the heat capacity by reducing the thickness of the heating roller in order to shorten the start-up time. In this method, heat is taken away by the transfer paper passing through the fixing device during the printing operation. It becomes easy. Therefore, more heating, that is, electric power is required during the printing operation, particularly during the printing operation immediately after starting up the apparatus.

  Further, the image forming apparatus includes an image reading unit provided with an automatic document feeder (ADF) that operates at the time of document reading, and a post-processing device that performs post-processing such as collation and bookbinding of transfer paper after image formation is completed. As a result, the overall power consumption tends to increase.

  On the other hand, generally available commercial power supplies have standards such as a maximum total current consumption of 15 A, and power that can be supplied from a single plug is limited. When power exceeding this is used, power supply work is required, which imposes a burden on the user and is not preferable. Therefore, as in Patent Documents 1 and 2, when the device is not used, power is stored in an auxiliary power source that can be stored, and when the power consumption of the device increases, power is supplied from the auxiliary power source to some loads. It has been proposed. This technique enables so-called power leveling that reduces the maximum power consumption from the commercial power supply.

In recent years, an electric double layer capacitor having a small internal resistance and capable of charging / discharging with a large current has been increased in capacity and put into practical use as such a rechargeable power storage means.
JP 2000-315567 A JP 2004-236492 A JP 2002-162854 A

  However, the rechargeable auxiliary power source described above cannot supply sufficient power unless it is sufficiently charged. Further, since it is impossible to avoid a decrease in charge due to leakage current even when not in use, the stored power gradually decreases in a non-charged state. For this reason, in Patent Document 1, power is supplied to the fixing device using an auxiliary power source when the apparatus is started up. However, if the auxiliary power source is not fully charged, desired heating cannot be performed. The fixing temperature cannot be reached. As a result, the start of printing may be delayed and image formation efficiency may be reduced.

  In recent years, in order to shorten the time until the fixing device can be used, in addition to the roller thinning described above, a so-called IH type heating device using an induction heating method as a heating source has been used. Yes. However, in this case, since the output current from the rechargeable auxiliary power source is a direct current, it is difficult to superimpose the power from the auxiliary power source on the IH heating that requires the application of an alternating current. Further, in the configuration including a dedicated heating source driven by an auxiliary power source as in Patent Document 3, the entire fixing device becomes large and the cost becomes high.

  On the other hand, Patent Document 2 includes a configuration for assisting power other than heating of the fixing device. However, since power consumption prediction of each load is used for power assist switching and charging current determination, the operation modes are diverse in recent years. Control is complicated in the composite image forming apparatus. In addition, the error in the calculation of instantaneous power becomes large during the simultaneous operation of a plurality of loads, and the maximum power that can be supplied by the commercial power supply may be exceeded for a long time.

  Further, as shown in FIG. 6, when a halogen lamp is used for heating the fixing device, the lighting ratio is adjusted when adjusting the average power (average power consumption) because the power consumption of the lamp is constant. . Therefore, the instantaneous maximum power consumption is constant during the lamp lighting period and does not decrease. Therefore, even if the surplus power is used for charging the auxiliary power supply, it is almost impossible to reduce the maximum power consumption.

  In addition, charging to the auxiliary power source becomes intermittent and not efficient. Furthermore, in order to increase the charging speed, the charging current at the time of charging must be increased, so that the power supply capacity on the charging current supply side also increases.

  The present invention uses a rechargeable auxiliary power supply to reduce the maximum current consumption of the main body and efficiently charge the auxiliary power supply with surplus power so that the maximum current consumption can be supplied without reducing productivity as much as possible. An object of the present invention is to provide an image forming apparatus that can be adjusted to a maximum current or less.

In order to achieve the above object, an image forming apparatus according to claim 1 is an image forming apparatus that operates a plurality of loads to form an image on a sheet, and is connected to a commercial power source, and a DC power is supplied to the plurality of loads. A first power supply means for supplying power, and a second power supply for supplying DC power to at least one specific load of the plurality of loads, the second power being charged by the power supplied from the first power supply means Power supply means, switching means for switching a power supply path so as to supply power from one of the first power supply means and the second power supply means to the specific load, and supplied from the commercial power supply The charging current of the second power supply means is controlled so that the current to be supplied does not exceed the maximum supply power of the commercial power supply, and the switching means causes the first power supply means to the specific load. When the driving current of the specific load increases to a first predetermined value in a state where power is being supplied, the switching means is configured to supply electric power to the specific load from the second power supply means. When the output current of the second power supply means falls below a second predetermined value in a state where power is supplied from the second power supply means to the specific load, the first power supply means Control means for controlling the switching means so as to supply power to the specific load .

According to the present invention, it is possible to reduce the total power consumption of the image forming apparatus, and as a result, it is possible to prevent the maximum power that can be supplied by the commercial power source from being exceeded for a long time.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a longitudinal sectional view showing a schematic configuration of a copying machine to which an image forming apparatus according to a first embodiment of the present invention is applied.

  In FIG. 1, an image forming apparatus according to the present embodiment is a copying machine using an electrophotographic process, and a reader unit 100 as an image reading unit that reads an image from a document, and prints the read image on a sheet (transfer paper). Printer unit 200.

  The reader unit 100 includes an automatic document feeder 300, and is an image reading device that can read a document alone or continuously. The automatic document feeder 300 feeds a document placed on a document stacking table (not shown) to a predetermined position on the document table glass 2.

  Further, the reader unit 100 includes a scanner 4 including a document illumination lamp 3, a scanning mirror 5, and the like. When the document is placed on the platen glass surface by the automatic document feeder 300, the scanner 4 scans the scanner 4 in a predetermined direction and passes reflected light of the document through the lens 8 via the scanning mirrors 5-7. The image is formed on the image sensor unit 101.

  The printer unit 200 includes an exposure control unit 10 constituted by a laser scanner, a control unit 202, a photosensitive drum 11, developing units 12 and 13, paper supply units 14 and 15, and a transfer separation charger 16. . The exposure control unit 10 irradiates the photosensitive drum 11 with a light beam modulated based on image data output from an image signal control unit (not shown) in the control unit 202.

  The developing units 12 and 13 visualize the electrostatic latent image formed on the photosensitive drum 11 with a predetermined color developer (toner). The sheet supply units 14 and 15 store a standard size sheet as a storing unit, and are fed to the position where the registration roller 25 is arranged by driving the feed roller, and then temporarily stopped, and then formed on the photosensitive drum 11. The paper is re-fed in a state where the image leading edge alignment timing with the image is taken.

  After the toner image developed on the photosensitive drum 11 is transferred to a sheet, the sheet is separated from the photosensitive drum 11 by the transfer separation charger 16 and conveyed to a fixing unit (fixing device) 211 via a conveyance belt. The The fixing unit 211 includes a fixing roller 22 and a pressure roller 17 formed of metal, and a coil that generates a magnetic field, and is configured by an induction heating type that generates heat from the magnetic field generated by the coil. .

  The fixing unit 211 performs pressure-contact heating and fixing of the toner image onto the sheet when the sheet passes through a nip formed by the facing portion of the fixing roller 22 and the pressure roller 17. The sheets on which image formation has been completed are stacked and discharged onto a discharge tray 20 by discharge rollers 18. The direction flapper 21 switches the transport direction of the paper on which image formation has been completed to the paper discharge port and the internal transport path direction, and prepares for the multiplex / double-side image forming process. The paper discharge sensor 19 monitors a paper discharge conveyance state.

  As described above, the copying machine forms an electrostatic latent image by sequentially irradiating the uniformly charged photosensitive drum 11 with laser light modulated based on image data, and then A toner image is formed on the photosensitive drum by supplying toner to the latent image. Then, the toner image is transferred to a sheet conveyed from the sheet supply unit 14 or the like at the image transfer position to form an image on the sheet, and then the image is fixed to the sheet by pressure-contact heating by the fixing unit 211.

  FIG. 2 is a block diagram showing a configuration of a portion related to power supply in the copying machine of FIG.

  The commercial power supply 201 is a power supply source that inputs AC power into the copier from the outside. The maximum current value that can be supplied from the commercial power supply 201 to the printer unit 200 is 15A. The commercial power source 201 is connected to an AC load 212 such as a fixing unit 211, a DC power source 204, and a paper heater (not shown) and an environmental heater disposed in each part in the main body.

  The DC power supply 204 (first power supply means) includes a plurality of loads that operate inside a copying machine such as a DC load 213 such as a paper conveyance motor, a solenoid, actuators and sensors such as a solenoid, a display LED, and a reader unit 100. To supply power.

  The control unit 202 controls the operation of each unit in the printer unit 200. The capacitor module 203 (second power supply means) is configured by connecting a plurality of large-capacity electric double layer capacitors in series, for example. The capacitor module 203 is an auxiliary power source that can store power supplied from the DC power source 204 and can supply power (voltage Vr × current Ir ′) for driving the reader unit 100 for a predetermined time. The current Ir ′ is a reader unit driving current for driving the reader unit 100 including the automatic document feeder 300.

  Reference numeral 206 denotes a changeover switch (switching means) that switches the reader unit 100 to supply power from either the DC power supply 204 or the capacitor module 203. The changeover switch 206 is controlled by a changeover signal 208 from the control unit 202.

  When the changeover switch 206 is switched to the DC power supply 204 side, the control unit 202 (control unit) is configured to supply the current Ir of the power supplied to the reader unit 100 by the first DC current detection unit 214 (driving unit driving). Current). In addition, the control unit 202 measures the current Ibackup (discharge current) of the power supplied to the reader unit 100 by the second DC current detection unit 216 when the changeover switch 206 is switched to the capacitor module 203 side. To do. Further, the control unit 202 measures the terminal voltage Vcap (charging voltage) of the capacitor module 203 based on the capacitor voltage detection signal 210, and measures the remaining power that can be supplied by the capacitor module 203.

  The current control FET 207 controls the charging current Ichg from the DC power source 204 to the capacitor module 203. The charging current Ichg is determined by the frequency and ON ratio of the charging current control signal 209 that controls the driving of the current control FET 207 from the control unit 202 and can be changed. The current control FET 207 and the DC power source 204 constitute a constant current source as a charging unit that extracts a predetermined current from the output of the DC power source 204 and supplies it to the capacitor module 203. A capacitor module 203 is connected to the source side of the current control FET 207 via a backflow prevention diode 215. The fixing unit 211 is supplied with a current Ifix for performing induction heating from the commercial power source 201.

  Next, a power control method in the copier of FIG. 1 will be described with reference to FIGS.

  FIG. 3 is a state transition diagram showing transition of average power of Itotal, Vcap, Ichg, and fixing unit 211 in each operation mode of the copying machine. 7 and 8 are flowcharts showing an example of power control processing in the copying machine.

  When the apparatus is powered on, the control unit 202 outputs a signal for switching the changeover switch 206 to the DC power supply 204 side so that the capacitor module 203 enters the charging mode (step S701 in FIG. 7). As a result, the capacitor module 203 enters a charging mode (301 in FIG. 3).

  The fixing unit 211 operates at the maximum power in order to set the fixing roller 22 to a target fixing temperature within a predetermined time. At this time, since the image forming operation on the photosensitive drum 11 is impossible, loads such as other motors do not operate. Therefore, the AC total current (Itotal) is equal to or less than the AC upper limit current (AC maximum power equivalent current). However, when the terminal voltage Vcap of the capacitor module 203 does not reach the capacitor saturation voltage due to discharge or the like, there is a possibility that the upper limit current of AC is exceeded when the charging current Ichg is passed. Therefore, the control unit 202 stops driving the current control FET 207 by the charging current control signal 209 and controls the charging current control signal so that the charging current Ichg = 0 (step S702 in FIG. 7).

  When the fixing roller 22 reaches the target temperature, the fixing unit 211 enters a standby state, and the power consumed by the fixing unit 211 is reduced to a value necessary to keep the temperature of the fixing roller 22 constant. As a result, surplus power is generated and the capacitor module 203 can be charged. In this standby state, the control unit 202 outputs a charging current control signal so that the charging current Ichg becomes a predetermined value so that the total power does not exceed the AC maximum power (step S703 in FIG. 7). As a result, the capacitor module 203 is charged (302 in FIG. 3).

  The control unit 202 determines whether or not the terminal voltage Vcap of the capacitor module 203 has reached the upper limit voltage (capacitor saturation voltage) (step S704 in FIG. 7). When the terminal voltage Vcap reaches the upper limit voltage, the control unit 202 controls the charging current control signal so that the charging current Ichg = 0 again (step S705 in FIG. 7). As a result, charging stops.

  In the standby state described above, the fixing unit 211 increases the average power consumption (fixing average power) of the fixing unit 211 to Pfix3 as necessary so as to keep the temperature of the fixing roller 22 at the standby target temperature. (Step S706 in FIG. 7).

  When a document is loaded on the automatic document feeder 300 during standby and an instruction to start copying is given, the reader unit 100 turns on the document illumination lamp 3 for driving and illuminating the document, driving the reader unit 100, and the like. Power consumption increases. That is, the reader part drive current Ir increases. The read document image is stored in a storage device (not shown) such as an HD (hard disk) in the control unit 202.

  Subsequently, a printing operation for printing the image on a sheet is started. When the printing operation is started, the fixing unit 211 averages power consumption (fixing average power) of the fixing unit 211 so as to keep the temperature of the fixing roller 22 at a target temperature in order to replenish heat lost by the passage of the sheet. Is increased to Pfix1 (step S707 in FIG. 7).

  In addition, loads such as other motors and solenoids perform operations such as transporting paper in a predetermined sequence from the paper supply units 14 and 15 to the paper discharge tray 20 via the image forming unit, so that the AC current consumption Itotal is To increase. As a result, the AC power upper limit (AC maximum power equivalent current) is exceeded during maximum consumption. Therefore, the control unit 202 determines whether or not the reader unit drive current Ir (Ir ′) has increased to a predetermined value via the first DC current detection unit 214 (step S708 in FIG. 7). By detecting that the reader unit drive current Ir (Ir ') has increased to a predetermined value, it is determined that the reader unit 100 is also operating in parallel with the printing operation. Next, the control unit 202 switches the changeover switch 206 to the capacitor module 203 side by the switching signal 208 so as to supply the power stored in the capacitor module 203 to the reader unit 100 via the DC / DC converter 205 (FIG. 7). Step S709). As a result, the capacitor module 203 enters the discharge mode (303 in FIG. 3). As a result, since the output current of the DC power supply 204 is decreased, the AC consumption current Itotal is also decreased to be equal to or less than the AC maximum power.

  On the other hand, the output current Ibackup of the capacitor module 203 is Ir ′ while the reader unit 100 is operating. If the power supply from the capacitor module 203 is continued as it is, the remaining power of the capacitor module 203 decreases, and the terminal voltage Vcap of the capacitor module 203 decreases in proportion thereto. However, the voltage Vr applied to the reader unit 100 is adjusted by the DC / DC converter 205 and is constant (303 in FIG. 3) regardless of the terminal voltage Vcap of the capacitor module 203 as described above.

  In general, the time required for reading a document is one reading time × number of sheets, but the printing operation is finished first and the printing operation is continued, for example, when multiple copies are designated. There is. Therefore, the control unit 202 determines whether or not the output current Ibackup of the capacitor module 203 has decreased below a certain value by the second DC current detection unit 216 (step S710 in FIG. 7).

  When Ibackup becomes a certain value or less, the control unit 202 determines that the document reading operation is finished, and switches the changeover switch 206 to the DC power supply 204 side by the changeover signal 208 again (step S711 in FIG. 7). As a result, the capacitor module 203 stops discharging and enters the charging mode (304 in FIG. 3). However, since charging current Ichg = 0, charging is not performed.

  On the other hand, since the reader unit 100 is stopped, the reader unit drive current Ir is equal to or less than a predetermined value, and the AC consumption current Itotal is also decreased to be equal to or less than the AC maximum power (304 in FIG. 3). At this time, in a general copying machine, an image of a document is read and stored in advance by the reader unit 100 for the next copying operation even if the printing operation is not completed, or via a network such as a LAN. Operations such as transmission to the outside can be performed.

  Regardless of the printing operation during printing, when the reader unit 100 is used again, the reader unit drive current Ir increases. Therefore, the control unit 202 determines whether or not the reader unit drive current Ir has increased to a predetermined value (step S712 in FIG. 8). When the reader unit drive current Ir increases to a predetermined value, the control unit 202 switches the changeover switch 206 to the capacitor module 203 side so that power is again supplied from the capacitor module 203 to the reader unit 100 (step S713 in FIG. 8). ). As a result, the capacitor module 203 enters the discharge mode (305 in FIG. 3).

  Thereafter, the remaining power of the capacitor module 203 decreases. The control unit 202 determines whether or not the terminal voltage Vcap of the capacitor module 203 has reached the lower limit value based on the capacitor voltage detection signal 210 (step S714 in FIG. 8). When the lower limit value is reached, the control unit 202 switches the changeover switch 206 to the DC power supply 204 side again (step S715 in FIG. 8), and controls so that power supply to the reader unit 100 is continued.

  When the changeover switch 206 is switched, the AC consumption current Itotal also rises again by the consumption current Ir of the reader unit 100. For this reason, the control unit 202 controls the fixing unit 211 to control the average fixing power to Pfix2 (maximum power consumption for fixing) so as not to exceed the AC maximum power (step S716 in FIG. 8). At this time, in order to prevent the fixing temperature from being excessively lowered due to insufficient power of the fixing unit 211, the number of image formations (productivity) per unit time is temporarily reduced such as by reducing the sheet conveyance speed or by increasing the conveyance interval. Control to reduce is also performed.

  When the control unit 202 determines that the second document reading operation (reading 2) is completed based on the measurement result by the first DC current detection unit 214 (step S717 in FIG. 8), the fixing average power is set to Pfix1. (Step S718 in FIG. 8). Further, the lowered paper transport speed or transport interval is restored to restore the productivity.

  Thereafter, when the printing operation is completed and the apparatus enters a standby state, the charging current Ichg is set to a predetermined value and the capacitor module 203 is charged (step S719 in FIG. 8). As a result, since the terminal voltage Vcap of the capacitor module 203 also increases again, when the control unit 202 detects that the saturation voltage has been reached again (step S720 in FIG. 8), the charging current Ichg = 0 is set and charging is performed. The process ends (step S721 in FIG. 8). Thereafter, step S706 and subsequent steps are repeated.

  According to the first embodiment, in the copying machine as the image forming apparatus, the changeover switch 206 is switched to supply power from the DC power source 204 or the capacitor module 203 to the reader unit 100 which is a specific load. Is provided. If the sum of the power supplied to the specific load measured by the first DC current detection unit 214 and the power used by the other loads exceeds the maximum power that can be supplied by the commercial power supply 201, the power to the specific load The changeover switch is controlled so that the supply is performed from the capacitor module 203. As a result, even when the total power consumption of the entire image forming apparatus exceeds the maximum power that can be supplied by the commercial power supply, the power supply path is switched so that the specific load is driven by the power from the power supply source that can be charged. It is possible to reduce the total power consumption.

[Second Embodiment]
The image forming apparatus according to the second embodiment of the present invention has the same configuration (FIG. 1) as that of the image forming apparatus according to the first embodiment. Hereinafter, the image forming apparatus according to the first embodiment will be described. Only the differences will be described.

  FIG. 4 is a block diagram showing a configuration of a portion related to power supply in the image forming apparatus according to the second embodiment of the present invention. Note that the same components shown in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted.

  In FIG. 4, a sub DC power source 402 (third power supply unit) is an auxiliary power source that exclusively takes over supply of drive power to the reader unit 100 and supply of charge power to the capacitor module 203. Therefore, the DC power source 204 is not involved in supplying power to the reader unit 100 and charging the capacitor module. The third current detection unit 401 (current measurement unit) measures the sum of the current Ir to the reader unit 100 and the charging current Ichg to the capacitor module 203 and notifies the control unit 202 of the total. The FAN 403 is a fan as a cooling unit for mainly cooling the sub DC power source 402.

  When the maximum current that can be supplied by the sub DC power source 402 is Imaxsup, and the charging current is set so that Imaxsup≈Irmax (Irmax: the maximum value of the reader unit current Ir), the power supply capability of the sub DC power source 402 is unnecessarily increased. Economical without design. Further, the power that can be supplied by the sub DC power source 402 is set to a capacity capable of continuously driving at least the reader unit 100 which is a specific load (a plurality of originals can be fed and read).

  As described in the first embodiment, the changeover switch 206 is switched to the sub DC power source 402 side, so that the capacitor module 203 is stopped from being discharged, that is, in a chargeable state. At this time, if the printer unit 200 is not operating, the control unit 202 controls the charging current Ichg by the current control FET 207 based on the measurement result by the third current detection unit 401 so that the following formula is obtained.

Imaxsup = Ir + Ichg
As described above, when the capacitor module 203 is in a chargeable state, the control unit 202 performs power supply to the reader unit 100 and charging power to the capacitor module 203 at a predetermined current value as current setting means. Control. As described above, the predetermined current value is the maximum current that can be supplied by the sub DC power supply 402. The charging current Ichg is optimized from time to time by the control unit 202 so as not to exceed the maximum current that can be supplied by the sub DC power supply 402 from the measurement result by the third current detection unit 401.

  Further, the charging current Ichg = 0 may be set so that the AC consumption current Itotal does not exceed the AC maximum current during printing, regardless of the measurement result by the third current detection unit 401.

  Further, the control unit 202 measures the output current of the sub DC power source 402 by the third current detection unit 401, and when the measured output current is a predetermined value or more, for example, 80% or more of Imaxsup, the FAN 403 is rated. Control to operate with current. Thereby, the temperature rise of the sub DC power supply is prevented.

  According to the second embodiment, the sub DC power source 402 that can supply the driving power to the reader unit 100 and the charging power to the capacitor module 203 is provided. When the capacitor module 203 is not supplying power, the sub DC power supply 402 supplies power to the reader unit 100. Then, the power supply path is switched so as to charge the capacitor module 203 with a predetermined current value. Accordingly, the chargeable auxiliary power source can be efficiently charged, and the productivity of the image forming apparatus can be increased.

[Third Embodiment]
The image forming apparatus according to the third embodiment of the present invention has the same configuration (FIG. 1) as that of the image forming apparatus according to the first embodiment. Hereinafter, the image forming apparatus according to the first embodiment will be described. Only the differences will be described.

  FIG. 5 is a state transition diagram when time elapses in each operation mode in the image forming apparatus according to the third embodiment of the present invention. In addition, about the same component shown in FIG. 3, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  In FIG. 5, after the first document reading operation (reading 1) is completed, the reading pause time Twait occurs until the second document reading operation (reading 2) starts. Here, in the said 1st Embodiment, the changeover switch 206 was switched to the DC power supply 204 side, and it once switched from the discharge mode to the charge mode (304).

  In the third embodiment, the discharge mode is not switched to the charge mode immediately after the document reading operation is completed, but is switched after a predetermined time (delay time Tdly) has elapsed since the end of the operation. That is, the control unit 202 compares the reading pause time Twait and the delay time Tdly, and if Tdly> Twait, does not switch from the discharge mode to the charge mode, that is, does not switch the power supply path by the changeover switch 206. To control. For example, when the document reading operation is frequently performed, the changeover switch 206 does not frequently switch each time the document reading operation is performed, and it is possible to reduce the operation sound at the time of switching and extend the mechanical life of the SW unit. (501). It is appropriate that the delay time Tdly is derived empirically in consideration of the consumption of the capacitor module 203 due to the resting power of the reader unit 100.

  In addition, when the remaining power of the capacitor module is equal to or less than a predetermined threshold, the control unit 202 prohibits the changeover switch from being switched to the capacitor module side, and the total power consumption in the apparatus is the maximum that the commercial power supply can supply. You may control so that it may become below electric power.

  In the third embodiment, the case where the present invention is applied to the first embodiment has been described. However, it is needless to say that the present invention can be applied to the second embodiment and the same effect can be obtained.

[Fourth Embodiment]
In the first and second embodiments, the specific load assisted by the capacitor module 203 is the reader unit 100. However, the load is not limited to this as long as it is a load that is connected to the printer unit 200 as the main body and operates intermittently, and power leveling with power assistance is possible by the same control method as described above.

  Further, although the current control FET 207 is used to control the charging current to the capacitor module 203, other current adjusting elements can be used as long as a necessary variable current can be given to the capacitor module 203.

  In the first and second embodiments, the charging current Ichg is set to 0 except during standby in which continuous charging is possible. However, when the fixing unit 211 is an induction heating type fixing device, the fixing unit 211 is used. The electric power supplied to is continuously varied according to the fixing unit temperature. Even if constant power is supplied to the fixing unit 211, if the temperature of the fixing unit 211 is saturated, the power supplied to the fixing unit 211 can be gradually reduced. Then, it is possible to increase the charging current Ichg in proportion to the decrease, and suppress the decrease in the remaining power of the capacitor module 203.

  In the first to fourth embodiments, the reader unit 100 has been described as a load connected to the printer unit 200. However, the reader unit 100 is not limited to this, and any other peripheral device can be used as long as it is a load that operates intermittently. Also good.

1 is a longitudinal sectional view showing a schematic configuration of a copying machine to which an image forming apparatus according to a first embodiment of the present invention is applied. FIG. 2 is a block diagram showing a configuration of a portion related to power supply in the copying machine of FIG. 1. FIG. 6 is a state transition diagram illustrating transition of average power of Itotal, Vcap, Ichg, and fixing unit 211 in each operation mode of the copying machine. FIG. 6 is a block diagram illustrating a configuration of a portion related to power supply in an image forming apparatus according to a second embodiment of the present invention. FIG. 10 is a state transition diagram illustrating transition of average power of Itotal, Vcap, Ichg, and fixing unit 211 in each operation mode of the copier according to the third embodiment of the present invention. FIG. 10 is a state transition diagram showing a transition of electric power and auxiliary power supply charging current in an image forming apparatus using a conventional halogen lamp as a fixing device. 6 is a flowchart showing an example of power control processing in a copying machine (part 1). 6 is a flowchart showing an example of power control processing in the copying machine (part 2).

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Reader part 200 Printer part 202 Control part 203 Capacitor module 204 DC power supply 205 DC / DC converter 206 Changeover switch 207 Current control FET
211 Fixing part (fixing device)
212 AC load 213 DC load 214 1st DC current detection part 216 2nd DC current detection part

Claims (5)

In an image forming apparatus that forms an image on a sheet by operating a plurality of loads,
A first power supply means connected to a commercial power source and supplying DC power to the plurality of loads;
A second power supply means that is charged by the power supplied from the first power supply means and supplies DC power to at least one specific load of the plurality of loads;
Switching means for switching a power supply path so that power is supplied from one of the first power supply means and the second power supply means to the specific load;
The charging current of the second power supply means is controlled so that the current supplied from the commercial power supply does not exceed the maximum supply power of the commercial power supply, and the specific power is determined from the first power supply means by the switching means. In a state where power is supplied to the load, when the drive current of the specific load increases to a first predetermined value, the switching means is configured to supply power to the specific load from the second power supply means. When the output current of the second power supply means falls below a second predetermined value in a state where power is supplied from the second power supply means to the specific load, the first power supply means An image forming apparatus comprising: control means for controlling the switching means so as to supply power to the specific load .   A charging unit configured to fix the toner image formed on the sheet; and charging the second power supply unit while the switching unit supplies power from the second power supply unit to the specific load. 2. The image forming apparatus according to claim 1, wherein when the voltage drops to a predetermined lower limit voltage, the control unit reduces the power consumed by the fixing unit. Storage means for storing paper,
Transport means for transporting paper from the storage means,
The image forming apparatus according to claim 2, wherein the control unit performs control to increase a sheet conveyance interval by the conveyance unit or control to decrease a conveyance speed when reducing the power consumed by the fixing unit. apparatus.   A fixing unit configured to fix the toner image formed on the sheet; and when the fixing unit is heated to a target temperature in response to power-on of the image forming apparatus, the control unit includes the second power supply unit. The image forming apparatus according to claim 1, wherein the charging current is controlled so as not to be charged. 2. The image forming apparatus according to claim 1, wherein the specific load is a reading device that reads an image of a document, and the reading device can operate independently of the image formation during image formation on a sheet. Equipment .

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