JP5233297B2 - Power supply device and image forming apparatus using power supply device - Google Patents

Description

  The present invention relates to a power supply device including an auxiliary power supply and an image forming apparatus using the power supply device.

  The power supply device used in the image forming apparatus normally converts the AC voltage of the commercial power supply into a DC voltage by a rectifying / smoothing circuit, and then supplies the electric power to each load after making the voltage constant to a predetermined voltage. When using many loads, such as when copying, the commercial power supply alone is insufficient. To cope with this problem, if an auxiliary power source consisting of a capacitor is mounted on the image forming apparatus and the power of the commercial power source is charged in advance to this auxiliary power source, or if the power is insufficient or expected to be insufficient The electric power is supplied to each load by discharging from the auxiliary power source through the discharge circuit (see Patent Document 1).

  Since these loads require high voltage and large capacity power, it is desirable that the auxiliary power supply has a high breakdown voltage and a large capacity. However, capacitors generally have a low breakdown voltage, and in order to achieve a high breakdown voltage, it is necessary to connect many capacitor cells in series. In such a configuration, since many capacitors are used, it becomes very expensive. For this reason, the number of capacitors to be connected is reduced and a DC / DC converter (voltage converter) is provided in the discharge circuit at the rear stage of the capacitor, and the electric power discharged from the capacitor is boosted by the DC / DC converter, Is supplied to each load.

JP 2004-286869 A

  However, when power is supplied to a load that generates an inrush current (starting current) with such a configuration, a large current from the capacitor temporarily flows to the subsequent load via the DC / DC converter at the start of driving the load. End up. When a large current flows, a power loss occurs due to the inductance of the DC / DC converter, causing a problem that efficiency is lowered. Moreover, since it is necessary to use the DC / DC converter using the element which can endure a large current, there exists a problem that cost starts.

  The present invention has been made in view of the above, and supplies a voltage required by a subsequent-stage load and inrush current (start-up) to a DC / DC converter (voltage conversion unit) at the start of driving the subsequent-stage load. It is an object of the present invention to provide a power supply device that can prevent inflow of current and an image forming apparatus using the power supply device.

In order to solve the above-described problems and achieve the object, the invention according to claim 1 converts an auxiliary power source charged with DC power and a voltage of the auxiliary power source, and temporarily converts the power after the voltage conversion. voltage converting means for have a first capacitor for storing a voltage conversion control means for controlling the voltage converting means, a voltage determining means for determining by comparing the voltage value with a predetermined value after voltage conversion, the voltage is provided between the conversion means and the load, comprising: a first switch for switching whether to supply power after voltage conversion to the load, and switching control means for controlling the first switch, the said When power is supplied to a load, the voltage conversion control means starts voltage conversion by the voltage conversion means in a state where the switching control means turns off the first switch, and after the voltage conversion starts, the first To the capacitor When the obtained voltage value exceeds a predetermined first value, after the voltage conversion control means stops voltage conversion by the voltage conversion means, the switching control means turns on the first switch, and The voltage conversion control means starts voltage conversion by the voltage conversion means when a predetermined time has elapsed since the switch 1 is turned on .

According to a second aspect of the present invention, there is provided an auxiliary power source charged with DC power, a voltage converting means having a first capacitor for converting the voltage of the auxiliary power source and temporarily storing the electric power after the voltage conversion, A voltage conversion control means for controlling the voltage conversion means; a first switch provided between the voltage conversion means and the load; for switching whether or not to supply power after voltage conversion to the load; and the first switch Switching control means for controlling the switch, and when power is supplied to the load, the voltage conversion control means turns off the voltage generated by the voltage conversion means while the switching control means turns off the first switch. When the voltage value stored in the first capacitor after the start of the voltage conversion exceeds a predetermined first value, the voltage conversion control unit stops the voltage conversion by the voltage conversion unit. When the switching control unit turns on the first switch and the voltage value of the first capacitor falls below a predetermined second value, the voltage conversion control unit starts voltage conversion by the voltage conversion unit. It is characterized by making it .

The invention according to claim 3 is the power supply device according to claim 1 or 2 , further comprising charging means for converting AC power from the AC power source into DC power and charging the auxiliary power source. Features.

According to a fourth aspect of the present invention, there is provided the power supply device according to the third aspect , further comprising constant voltage power supply means for converting an AC voltage of the AC power supply into a DC voltage, wherein the charging means is the constant voltage power supply means. The auxiliary power supply is charged with the DC power converted by the above-mentioned feature.

Further, the invention according to claim 5 is the power supply device according to claim 3 or 4 , further comprising interface means for transmitting / receiving a signal to / from an external device, wherein the charging means is based on a signal received by the interface means. An operation state of the external device is detected, and charging of the auxiliary power source is controlled according to the operation state.

According to a sixth aspect of the present invention, in the power supply device according to the fifth aspect , the voltage conversion control unit detects an operation state of the external device based on a signal received by the interface unit, and responds to the operation state. And controlling voltage conversion of the voltage conversion means.

According to a seventh aspect of the present invention, in the power supply device according to any one of the first to sixth aspects, the auxiliary power source is a second capacitor.

According to an eighth aspect of the present invention, in the power supply device according to any one of the first to seventh aspects, the voltage converting means includes a second switch, and the second switch is soft-switched. To convert the voltage of the auxiliary power source.

According to a ninth aspect of the present invention, in the power supply device according to any one of the first to eighth aspects, the voltage converting means boosts the voltage of the auxiliary power supply.

The invention according to claim 10 is the power supply device according to any one of claims 1 to 9 , wherein the load is a heater.

The invention according to claim 11 is the power supply device according to any one of claims 1 to 9 , wherein the load is a motor.

According to a twelfth aspect of the present invention, the power supply device according to any one of the first to eleventh aspects is provided.

  According to the present invention, when a voltage stored in a capacitor serving as an auxiliary power supply is converted into a high voltage by a discharge circuit and supplied to a subsequent load, the capacitor constituting the DC / DC converter (voltage conversion unit) of the discharge circuit is supplied. When a certain amount of post-transformation charge is stored, switching (voltage conversion) of the switches that make up the DC / DC converter is temporarily stopped, and the charge is fed to the subsequent load. There is an effect that it is possible to prevent an inrush current (starting current) from flowing to the DC / DC converter at the start of driving.

  Exemplary embodiments of a power supply apparatus and an image forming apparatus using the power supply apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings. In this embodiment, an example in which the image forming apparatus using the power supply device of the present invention is applied to a copying machine is shown. However, the present invention is not limited to this and is also applied to a multifunction machine, a printer, a facsimile machine, and the like. It is possible.

(First embodiment)
FIG. 1 is a hardware configuration diagram showing an example of a copying machine according to the first embodiment of the present invention. The copying machine 100 includes an automatic document feeder (ADF) 101, a scanner unit 102, an image writing unit 103, a photosensitive unit 104, a developing unit 105, a primary transfer unit 106, a paper feeding unit 107, a secondary transfer unit 108, and a conveyor belt. 109, the fixing unit 110, and the power supply device 1.

  An automatic document feeder (ADF) 101 sequentially sends documents to the scanner unit 102. The scanner unit 102 reads an image by reading reflected light from a document while irradiating the document with light. The image read by the scanner unit 102 is subjected to image processing and then sent to the image writing unit 103. The image writing unit 103 drives an LD (laser diode) according to the image data to form a latent image on the photosensitive drum in the photosensitive unit 104. In the case of full color, the photoconductor unit 104 includes four photoconductor drums of Y (yellow), M (magenta), C (cyan), and Bk (black). The developing unit 105 causes toner to adhere to the latent image formed on the photosensitive drum and visualize it.

  The image visualized on the photosensitive drum is transferred onto the intermediate transfer belt of the primary transfer unit 106. In the case of full color, four color toners are sequentially stacked. When the image forming and transferring processes for four colors are completed, the transfer paper is fed from the paper feeding unit 107 in synchronization with the primary transfer belt 106, and between the primary transfer unit 106 and the secondary transfer roller 108, The toner is transferred from the transfer belt to the transfer paper simultaneously for the four colors. The conveyance belt 109 conveys the transfer paper on which the toner is transferred. The fixing unit 110 heats and pressurizes the toner on the transfer paper sent by the conveyance belt 109 to fix the formed toner image.

(Power supply)
The power supply device 1 supplies power to the heater of the fixing unit 110 and other loads such as a motor. FIG. 2 is a block diagram showing the configuration of the power supply device 1 according to the first embodiment of the present invention. The power supply device 1 includes a constant voltage power supply circuit 2, a charger 3, a capacitor 4, a discharge circuit 5, an output terminal 6, and an output terminal 7.

  The constant voltage power supply circuit 2 converts the AC voltage of the commercial AC power supply 8 into a predetermined DC voltage and supplies it to a load at the subsequent stage of the output terminal 6. The charger 3 converts the AC voltage of the commercial AC power supply 8 into a predetermined DC voltage and charges the capacitor 4. Normally, the voltage value converted by the constant voltage power supply circuit 2 is higher than the voltage value converted by the charger 3. The capacitor 4 is an auxiliary power source that supplies a discharge voltage (DC voltage) to the discharge circuit 5 by discharging after the electric charge is charged with the output voltage of the charger 3. As an example, the capacitor 4 uses an electric double layer capacitor having a relatively large capacitance. An aluminum electrolytic capacitor having a capacitance of 9900 μF or more may be used. In this example, a capacitor is used as an auxiliary power source, but a battery may be used.

  The discharge circuit 5 is a circuit that controls the discharge of the capacitor 4. Specifically, the discharge voltage from the capacitor 4 is converted into a high voltage and supplied to the load at the subsequent stage of the output terminal 7. The discharge circuit 5 includes a DC / DC converter 9, a conversion efficiency determination unit 10, and a switch element 11.

  The DC / DC converter 9 is a voltage conversion unit that soft-switches the voltage discharged from the capacitor 4 and converts it into a voltage that can be used by a subsequent load. Normally, the DC / DC converter 9 is a step-up type, and converts the low voltage of the capacitor 4 into a high voltage used by a subsequent load. FIG. 3 is a circuit diagram of the DC / DC converter 9. The DC / DC converter 9 includes a capacitor 12, a switch 13, and a control circuit 14. Note that this circuit is a basic circuit, and is actually equipped with an inrush current prevention circuit and various protection circuits.

  The capacitor 12 is provided at the last stage of the DC / DC converter 9 and temporarily stores electric charges with the converted (boosted) voltage. As an example, the capacitor 12 is an aluminum electrolytic capacitor.

  The switch 13 is a switching element, generates a desired boosted voltage by performing soft switching (switch opening / closing), and supplies the boosted voltage to the capacitor 12. Further, the switch 13 is turned off (opened) when a constant charge is stored in the capacitor 12 and generation of the conversion voltage is unnecessary, and the switch 13 is reduced by supplying the charge stored in the capacitor 12 to the subsequent load. When the output voltage from the capacitor 12 decreases, soft switching is started again.

  The control circuit 14 controls opening / closing (soft switching) of the switch 13 based on an instruction from a control unit (not shown) of the copier 100 or the conversion efficiency determination unit 10.

  The conversion efficiency determination unit 10 determines the state of the conversion voltage charged in the capacitor 12 (the conversion efficiency on the primary side and the secondary side of the DC / DC converter 9) as voltage determination means, and as a switching control means, the switch element 11 is controlled, and the control circuit 14 (opening and closing of the switch 13) is controlled as voltage conversion control means. The switch element 11 opens and closes to supply high-voltage power output from the DC / DC converter 9 to a subsequent load, or to cut off the supply.

  The output terminal 6 supplies the output power of the constant voltage power supply circuit 2 to the subsequent load. The output terminal 7 supplies the output power of the switch element 11 to the subsequent load.

  Next, the operation of the power supply device 1 configured as described above will be described. When necessary, the power supply device 1 directly supplies the power converted by the constant voltage power supply circuit 2 to a subsequent load (for example, the heater of the fixing unit 110), and the voltage stored in the capacitor 4 as a discharge circuit 5 In some cases, after being converted to a high voltage, indirect power is supplied to a subsequent load (for example, a heater of the fixing unit 110). Further, the power supply device 1 may simultaneously perform direct power supply to a subsequent load (for example, the heater of the fixing unit 110) and indirect power supply to a subsequent load (for example, a motor).

  Here, the voltage conversion operation of the DC / DC converter 9 when the voltage stored in the capacitor 4 is converted into a high voltage by the discharge circuit 5 and then fed to the subsequent load will be described.

  The control circuit 14 starts soft switching of the switch 13 in response to an instruction from a control unit (not shown) of the copying machine 100. At this stage, the switch element 11 is in an off (open) state. The voltage discharged from the capacitor 4 is converted (boosted) by the soft switching of the switch 13. Then, the converted electric charge is sent to the capacitor 12 and temporarily stored.

  The conversion efficiency determination unit 10 determines the state of the conversion voltage charged in the capacitor 12 (the conversion efficiency on the primary side and the secondary side of the DC / DC converter 9), and whether or not a certain amount of charge has accumulated in the capacitor 12 or not. Judging. Normally, the conversion efficiency determination unit 10 determines from the output voltage from the capacitor 12, but may determine from the output current or output power. When the conversion efficiency determination unit 10 determines that a certain amount of charge is accumulated in the capacitor 12 and a certain voltage is generated, the conversion efficiency determination unit 10 instructs the control circuit 14 to stop the soft switching of the switch 13 and to turn off (open) the switch 13. do. The control circuit 14 turns off (opens) the switch 13 in accordance with an instruction from the conversion efficiency determination unit 10. As a result, voltage conversion is temporarily stopped.

  Next, the conversion efficiency determination unit 10 turns on (closes) the switch element 11. As a result, the charge accumulated in the capacitor 12 flows from the output terminal 7 to the subsequent load, and drives the subsequent load.

  On the other hand, in the conventional power supply device, the switch element 11 is turned on (closed) without stopping the soft switching of the switch 13. In that case, if the subsequent load is a heater of the fixing unit 110, an inrush current (starting current) flows from the capacitor 4 to the heater via the DC / DC converter 9 when power supply is started in a state where the heater temperature is low. If the subsequent load is a motor, an inrush current (starting current) flows from the capacitor 4 to the heater via the DC / DC converter 9 when power feeding is started when the motor is not rotating. In either case, since a large current flows through the DC / DC converter 9, the loss increases and the efficiency decreases. Further, it is necessary to use an expensive DC / DC converter using an element capable of withstanding a large current.

  On the other hand, in the power supply device 1 according to the first embodiment, while the power supply to the subsequent load is started and the inrush current (starting current) flows, only the charge accumulated in the capacitor 12 flows to the subsequent load. No current flows in any other circuit. For this reason, a large current does not flow through the DC / DC converter 9. Since a large current does not flow, there is little loss and an inexpensive product that does not need to withstand the large current can be used.

  Since the inrush current (starting current) flows only for a short time immediately after the start of power supply to the load, the control circuit 14 automatically starts soft switching of the switch 13 after a predetermined time has elapsed. The voltage conversion is resumed, and thereafter normal operation is performed.

  Note that when the conversion efficiency determination unit 10 determines that the charge is discharged from the capacitor 12 and the voltage is lowered, the control circuit 14 may be instructed to start soft switching of the switch 13 and restart voltage conversion.

  As described above, according to the power supply device according to the first embodiment, when the voltage stored in the capacitor serving as the auxiliary power supply is converted into a high voltage by the discharge circuit and supplied to the subsequent load, the DC / When a certain amount of transformed charge is stored in the capacitor that constitutes the DC converter (voltage conversion unit), switching of the switch that constitutes the DC / DC converter (voltage conversion) is temporarily stopped, and then the charge is loaded into the subsequent load. Therefore, it is possible to prevent an inrush current (starting current) from flowing to the DC / DC converter when starting the driving of the subsequent stage load.

(Second Embodiment)
In the power supply device according to the second embodiment, a constant voltage power supply circuit for power factor improvement is further provided in the forefront of the power supply device according to the first embodiment.

  A second embodiment will be described with reference to the accompanying drawings. Since the configuration of the copying machine according to the present embodiment is the same as that of the copying machine according to the first embodiment except for the power supply device, the description is omitted with reference to the above description. Moreover, about the structural example of a power supply device, a different part from 1st Embodiment is demonstrated. The other parts are the same as those in the first embodiment, so the description is omitted with reference to the above description.

  FIG. 4 is a block diagram showing the configuration of the power supply device according to the second embodiment of the present invention. The power supply device 21 supplies power to the heater of the fixing unit and other loads. The power supply device 21 includes a constant voltage power supply circuit 2, a charger 3, a capacitor 4, a discharge circuit 5, an output terminal 6, an output terminal 7, and a constant voltage power supply circuit 22. The discharge circuit 5 includes a DC / DC converter 9, a conversion efficiency determination unit 10, and a switch element 11.

  The constant voltage power supply circuit 22 has a DC / DC converter for improving the power factor, and is provided between the commercial AC power supply 8, the constant voltage power supply circuit 2 and the charger 3. Then, the AC voltage of the commercial AC power supply 8 is converted into a predetermined DC voltage and supplied to the constant voltage power supply circuit 2 and the charger 3. For this reason, although energy saving is reduced a little compared with the power supply device 1 concerning 1st Embodiment, since the power factor of the electric power input from the commercial alternating current power supply 8 is improved, a power supply harmonic current is decreased. be able to. Note that any one, two, or all of the constant voltage power supply circuit 22, the constant voltage power supply circuit 2, and the charger 3 are preferably soft switching circuits.

  As described above, according to the power supply device according to the second embodiment, the power input from the commercial AC power supply is provided by further providing the constant voltage power supply circuit between the commercial AC power supply, the constant voltage power supply circuit, and the charger. Therefore, it is possible to efficiently use the power from the commercial AC power source.

(Third embodiment)
The power supply device according to the third embodiment is configured such that the functions of the constant voltage power supply circuit and the charger of the power supply device according to the first embodiment are shared by one circuit.

  A third embodiment will be described with reference to the accompanying drawings. Since the configuration of the copying machine according to the present embodiment is the same as that of the copying machine according to the first embodiment except for the power supply device, the description is omitted with reference to the above description. Moreover, about the structural example of a power supply device, a different part from 1st Embodiment is demonstrated. The other parts are the same as those in the first embodiment, so the description is omitted with reference to the above description.

  FIG. 5 is a block diagram showing a configuration of a power supply device according to the third embodiment of the present invention. The power supply device 31 supplies power to the heater of the fixing unit and other loads. The power supply device 31 includes a constant voltage power supply circuit 32, a capacitor 4, a discharge circuit 5, an output terminal 33, and an output terminal 7. The discharge circuit 5 includes a DC / DC converter 9, a conversion efficiency determination unit 10, and a switch element 11.

  The constant voltage power circuit 32 converts the AC voltage of the commercial AC power supply 8 into a predetermined DC voltage and directly supplies it to a load at the subsequent stage of the output terminal 33, and converts the AC voltage of the commercial AC power supply 8 into a predetermined DC voltage. Conversion and charging of the capacitor 4 are performed alternately. That is, the constant voltage power circuit 32 has a constant voltage supply function and a charging function. Normally, the voltage value that is converted so that the constant voltage power supply circuit 32 directly supplies the load to the subsequent stage is higher than the voltage value that is converted to be supplied to the capacitor 4. The constant voltage power supply circuit 32 includes a DC / DC conversion / charge circuit 34 and a switch element 35.

  The DC / DC conversion / charging circuit 34 alternately performs constant voltage operation of AC voltage (operation of converting AC voltage to a predetermined DC voltage) and charging operation of the capacitor 4. The DC / DC conversion / charging circuit 34 includes a DC / DC converter charger 36 and a switching control unit 37.

  The DC / DC converter charger 36 converts the AC voltage of the commercial AC power supply 8 into a predetermined DC voltage and supplies it to the load or the capacitor 4 at the subsequent stage of the output terminal 33. The DC / DC converter charger 36 may be soft-switched. Further, a DC / DC converter may be further provided in front of the DC / DC converter charger 36 to provide a constant voltage power source for power factor improvement.

  The switching control unit 37 controls switching between the constant voltage operation and the charging operation of the DC / DC conversion / charging circuit 34, and controls opening and closing of the switch element 35 as one of the controls.

  The switch element 35 opens and closes to supply the output power of the DC / DC converter charger 36 to the capacitor 4 and cut off the supply. In addition, when the supply of the output power of the DC / DC converter charger 36 to the capacitor 4 is interrupted by the switch element 35, the output power of the DC / DC converter charger 36 (constant voltage power supply circuit 32) is the output terminal. It is transmitted to the subsequent stage load via 33.

  Next, the operation of the power supply device 31 configured as described above will be described. When the DC / DC conversion / charge circuit 34 charges the capacitor 4, the switching control unit 37 turns on (closes) the switch element 35. Then, the DC voltage is supplied to the capacitor 4 and charging of the capacitor 4 is started. This charging is first performed with a constant current, then with a constant power, and finally with a constant current again.

  When the charging of the capacitor 4 is completed and the capacitor 4 separately discharges a voltage to the discharge circuit 5 (the subsequent load), the switching control unit 37 turns off (opens) the switch element 35. Further, the DC / DC conversion / charging circuit 34 is controlled at a constant voltage, and a required constant voltage is set. For this reason, the constant voltage converted into a direct current by the DC / DC conversion / charging circuit 34 is directly transmitted to the subsequent load via the output terminal 33. Therefore, one circuit is reduced as compared with the case where the constant voltage power supply circuit and the charger are provided, and the efficiency as the power supply device 31 is improved.

  Thus, according to the power supply device according to the third embodiment, since the constant voltage power supply circuit has both the constant voltage supply function and the charging function, there is no need to separately provide a charger. Space and cost can be reduced.

(Fourth embodiment)
In the power supply device according to the fourth embodiment, the power supply device according to the first embodiment further includes an interface unit that communicates with an external device such as the image forming apparatus main body.

  A fourth embodiment will be described with reference to the accompanying drawings. Since the configuration of the copying machine according to the present embodiment is the same as that of the copying machine according to the first embodiment except for the power supply device, the description is omitted with reference to the above description. Moreover, about the structural example of a power supply device, a different part from 1st Embodiment is demonstrated. The other parts are the same as those in the first embodiment, so the description is omitted with reference to the above description.

  FIG. 6 is a block diagram showing a configuration of a power supply device according to the fourth embodiment of the present invention. The power supply device 41 supplies power to the heater of the fixing unit and other loads. The power supply device 41 includes a constant voltage power supply circuit 2, a charger 3, a capacitor 4, a discharge circuit 5, an output terminal 6, an output terminal 7, and an interface unit 42. The discharge circuit 5 includes a DC / DC converter 9, a conversion efficiency determination unit 10, and a switch element 11.

  The interface unit 42 communicates with an external device 43 such as a copying machine main body. Specifically, the interface unit 42 receives a signal from the external device 43 and transmits the signal to the charger 3 and the discharge circuit 5.

  The charger 3 and the discharge circuit 5 detect the operation state of the external device 43 from the signal received from the external device 43, and perform charging or discharging according to the operation state. In the present embodiment, charging is possible when the operating state of the external device 43 is chargeable, and discharging is possible when the external device 43 can be discharged.

  In the present embodiment, the interface unit 42 transmits the reception signal from the external device 43 to the charger / discharger 3 and the discharge circuit 5, but the control unit of the discharge circuit 5 receives the reception signal from the external device 43. It may be configured to transmit to (not shown) and further output a signal from the control unit to the charger 3.

  In the present embodiment, the charger 3 and the discharge circuit 5 detect the operation state of the external device 43 from the received signal from the external device 43, and charge or discharge is performed according to the operation state. However, the charger 3 and the discharge circuit 5 may detect the charge / discharge mode required by the external device 43 from the received signal from the external device 43, and perform charging or discharging according to the charge / discharge mode.

  As described above, according to the power supply device according to the fourth embodiment, the charger and the discharge circuit detect the operation state of the external device received by the interface unit, and charge or discharge is performed according to the operation state. When the operating state of the external device can be charged, the battery can be charged and discharged. When the external device can be discharged, the total input current can be adjusted and the power consumption can be reduced.

(Fifth embodiment)
The power supply device according to the fifth embodiment specifically supplies the discharge power from the capacitor (auxiliary power supply) to the heater of the fixing unit and supplies the power from the constant voltage power supply circuit to the fan as a load in the subsequent stage. ing.

  A fifth embodiment will be described with reference to the accompanying drawings. Since the configuration of the copying machine according to the present embodiment is the same as that of the copying machine according to the first embodiment except for the power supply device, the description is omitted with reference to the above description. Moreover, about the structural example of a power supply device, a different part from 1st Embodiment is demonstrated. The other parts are the same as those in the first embodiment, so the description is omitted with reference to the above description.

  FIG. 7 is a block diagram showing a configuration of a power supply device according to the fifth embodiment of the present invention. The power supply device 51 supplies power to the heater of the fixing unit and the fan 52 that suppresses the temperature rise of the copying machine and the power supply device 51. The power supply device 51 includes a constant voltage power supply circuit 2, a charger 3, a capacitor 4, a discharge circuit 5, and a control unit 53. The discharge circuit 5 includes a DC / DC converter, a conversion efficiency determination unit, and a switch element.

  Note that the constant voltage power supply circuit 2 according to the present embodiment supplies a DC voltage to the fan 52 as a subsequent load. The discharge circuit 5 according to the present embodiment discharges a DC voltage to a heating source (heater) 55 built in the fixing roller 54 of the fixing unit as a subsequent load. The heating source 55 generates heat due to the discharge power from the discharge circuit 5.

  The controller 53 controls the charging of the commercial AC power by the charger 3 to the capacitor 4 and the discharging of the power stored in the capacitor 4 by the discharging circuit 5 to the heating source 55.

  Next, the operation of the power supply device 51 configured as described above will be described. The electric power from the commercial AC power supply 8 is connected to the charger 3 of the capacitor 4 through the main power switch 56 that supplies or cuts off the electric power. When the main power switch 56 is turned on (closed) and a charge on signal is output from the control unit 53 to the charger 3, the capacitor 4 is charged and charging is completed. Thereafter, when a discharge on signal is output from the control unit 53 to the discharge circuit 5, the energy stored in the capacitor 4 is discharged to the heating source 55 via the discharge circuit 5, and the fixing roller 54 is heated by the heating source 55. Is done. The temperature of the fixing roller 54 is monitored by a thermistor 57, and is fed back to a temperature control unit 58 that controls heating / cooling of a copying machine (external device) and the temperature is controlled. In addition, in order to prevent the temperature of the power supply device 51 from rising, heat generated in the power supply device 51 or in the copier (external device) attached is exhausted to the outside by the fan 52.

  The control voltage of the temperature control unit 58 of the copying machine (external device) may be supplied from either the power supply device 51 or another constant voltage power supply. The present embodiment is an example applied to a fixing unit used in a copying machine, but may be applied to other load devices.

  As described above, according to the power supply device according to the fifth embodiment, the discharge power from the capacitor (auxiliary power supply) is supplied to the heater of the fixing unit, and the power from the constant voltage power supply circuit is supplied to the fan. Is possible.

  Next, a program and a computer-readable recording medium according to the present invention will be described. By programming the functions described in the above embodiments and writing them in advance on a recording medium such as a ROM, mounting this ROM on the image forming apparatus, and executing the program in the ROM by the CPU or microprocessor there The object of the present invention can be achieved. In that case, the program and the recording medium constitute a program and a computer-readable recording medium according to the present invention. The recording medium may be any of a semiconductor medium (for example, ROM, nonvolatile memory card, etc.), an optical medium (for example, DVD, MO, MD, CD-R, etc.), or a magnetic medium (for example, magnetic tape, flexible disk, etc.). There may be. Further, the case where the operating system or the like performs part or all of the actual processing based on the instruction of the loaded program and the functions of the above-described embodiments are realized by the processing is also included. Further, when the above-mentioned program is stored in a storage device such as an HDD of a server computer and is downloaded and distributed from a user's computer connected via a network, or distributed and distributed from a server computer, The storage device of the server computer is also included in the recording medium of the present invention. In this way, by programming the function of the present invention, recording it on a recording medium and distributing it, it is possible to improve cost, portability and versatility.

1 is a hardware configuration diagram showing an example of a copying machine according to a first embodiment of the present invention. It is a block diagram which shows the structure of the power supply device concerning the 1st Embodiment of this invention. It is a circuit diagram of a DC / DC converter. It is a block diagram which shows the structure of the power supply device concerning the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the power supply device concerning the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the power supply device concerning the 4th Embodiment of this invention. It is a block diagram which shows the structure of the power supply device concerning the 5th Embodiment of this invention.

Explanation of symbols

1, 21, 31, 41, 51 Power supply device 2, 22, 32 Constant voltage power supply circuit 3 Charger 4 Capacitor 5 Discharge circuit 6, 7, 33 Output terminal 8 Commercial AC power supply 9 DC / DC converter 10 Conversion efficiency determination unit 11 Switch element 12 Capacitor 13 Switch 14 Control circuit 34 DC / DC conversion / charge circuit 35 Switch element 36 DC / DC converter charger 37 Switching control unit 42 Interface unit 43 External device 52 Fan 53 Control unit 54 Fixing roller 55 Heating source (heater) )
56 Main Power Switch 57 Thermistor 58 Temperature Control Unit 100 Copier 101 Automatic Document Feeder (ADF)
DESCRIPTION OF SYMBOLS 102 Scanner part 103 Image writing unit 104 Photosensitive unit 105 Developing unit 106 Primary transfer unit 107 Paper feed part 108 Secondary transfer unit 109 Conveyor belt 110 Fixing unit

Claims (12)

An auxiliary power source charged with DC power;
A voltage conversion unit that have a first capacitor for storing the voltage of the auxiliary power supply converts the power after voltage conversion temporarily
Voltage conversion control means for controlling the voltage conversion means;
Voltage determination means for comparing and determining a voltage value after voltage conversion and a predetermined value;
A first switch that is provided between the voltage conversion means and the load and switches whether or not to supply power after voltage conversion to the load;
Switching control means for controlling the first switch,
When supplying power to the load, the voltage conversion control unit starts voltage conversion by the voltage conversion unit in a state where the switching control unit turns off the first switch, and after the voltage conversion starts, the voltage conversion control unit starts the voltage conversion. When the voltage value stored in one capacitor exceeds a predetermined first value, the switching control means turns on the first switch after the voltage conversion control means stops voltage conversion by the voltage conversion means. And when a predetermined time has elapsed since the first switch is turned on, the voltage conversion control means starts voltage conversion by the voltage conversion means,
A power supply characterized by.   An auxiliary power source charged with DC power;
  A voltage conversion means having a first capacitor for converting the voltage of the auxiliary power supply and temporarily storing the electric power after the voltage conversion;
  Voltage conversion control means for controlling the voltage conversion means;
  A first switch that is provided between the voltage conversion means and the load and switches whether or not to supply power after voltage conversion to the load;
  Switching control means for controlling the first switch;
  With
  When supplying power to the load, the voltage conversion control unit starts voltage conversion by the voltage conversion unit in a state where the switching control unit turns off the first switch, and after the voltage conversion starts, the voltage conversion control unit starts the voltage conversion. When the voltage value stored in one capacitor exceeds a predetermined first value, the switching control means turns on the first switch after the voltage conversion control means stops voltage conversion by the voltage conversion means. When the voltage value of the first capacitor falls below a predetermined second value, the voltage conversion control means starts voltage conversion by the voltage conversion means,
  A power supply characterized by. The AC power from the AC power source into a DC power, wherein further comprising a charging means for charging the auxiliary power supply device according to claim 1 or 2, characterized in. Further comprising constant voltage power source means for converting the AC voltage of the AC power source into a DC voltage;
4. The power supply device according to claim 3 , wherein the charging unit charges the auxiliary power source with the DC power converted by the constant voltage power source unit. It further comprises interface means for transmitting and receiving signals with external devices,
5. The charging device according to claim 3 , wherein the charging unit detects an operating state of the external device based on a signal received by the interface unit, and controls charging of the auxiliary power source according to the operating state. 6. Power supply. Said voltage conversion control means detects the operation status of the external device by a signal said interface means receives, claim 5, wherein, to control the voltage conversion of the voltage conversion means in response to the operating state The power supply device described in 1. The power supply apparatus according to any one of claims 1 to 6 , wherein the auxiliary power supply is a second capacitor. It said voltage converting means comprises a second switch, by soft switching said second switch, to convert the voltage of the auxiliary power supply, in any one of claims 1 to 7, characterized in The power supply described. It said voltage converting unit, a power supply device according to any one of claims 1 to 8, characterized in that, to boost the voltage of the auxiliary power supply. The power supply apparatus according to any one of claims 1 to 9 , wherein the load is a heater. The power supply device according to any one of claims 1 to 9 , wherein the load is a motor. An image forming apparatus comprising the power supply device according to claim 1 .

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