JP2007127726A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which does not exceed the feedable electric power of a power line even in a steep change by supplying the electric power to a DC load through the use of an auxiliary power source with a simple configuration and a control method. <P>SOLUTION: The image forming apparatus having a power unit feeding AC power and DC power to a load has a capacitor charged with the DC power. The DC power with which the capacitor is charged is fed to the load for a predetermined period after a power source is turned on or after being returned from an off mode. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric power leveling technique for supplying power to an image forming apparatus, in particular, a DC load by an auxiliary power source so that power consumption does not exceed power that can be supplied from a power supply line.

  In recent years, copiers, printers, facsimiles, and multi-function machines that combine these using an electrophotographic process have become multifunctional, and accordingly, the structure has become complicated and the maximum power consumption tends to increase.

  Also, supply to the fixing heating device in order to reduce the waiting time until the start of the fixing device and the factors of the image forming apparatus itself such as the temporary interruption of the operation due to the lowering of the fixing temperature during the printing or copying operation and the waiting time of the operator. There is a tendency to increase electric power.

  On the other hand, since there is a limit to the power that can be supplied from the normal power supply line, this is a major limitation in designing the equipment.

  As a conventional technique for load power leveling, in Japanese Patent Laid-Open No. 2002-199588 (see Patent Document 1), a means for monitoring the power supply of the main power supply is provided, and the power supply of the main power supply is determined in advance. When the power is less than the predetermined value, the auxiliary power supply is charged. When the power supplied to the main power supply is higher than the predetermined value, the power stored in the auxiliary power supply is discharged. The technology to be converted is disclosed.

In Japanese Patent Application Laid-Open No. 2004-236492 (see Patent Document 2), the power consumption is predicted, and when the predicted power consumption exceeds the power that can be supplied from the main power source, power is supplied from the auxiliary power source to some loads. A power supply device that is controlled so as not to exceed the maximum suppliable power of the power supply line by supplying the power is disclosed.
JP 2002-199588 A JP 2004-236492 A

  However, in the invention disclosed in Patent Document 1, the power consumption is monitored, and feedback control is performed in which power is supplied from the auxiliary power source when the power supplied to the main power source exceeds a predetermined threshold. When the change in power is more steep than expected, there is a problem that the power supply capacity of the main power supply is exceeded. Alternatively, when the auxiliary power supply is operated earlier by lowering the threshold value in order to avoid such a problem, it is necessary to further increase the capacity of the auxiliary power supply in order to extend the usage time of the auxiliary power supply. There is a problem of increasing the scale.

  Further, the invention disclosed in Patent Document 2 predicts the power consumption, and therefore requires a lot of data, which causes a problem of complicated control.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can supply power even with a sudden change in load with a simple configuration.

  In order to achieve the above object, the image forming apparatus of the present invention has the following characteristics.

  The image forming apparatus of the present invention is an image forming apparatus having a power supply device that supplies AC power and DC power to a load, the image forming apparatus having a capacitor charged with the DC power, and the DC power charged in the capacitor Is supplied to the load for a predetermined period after turning on the power or returning from the off mode.

  Accordingly, it is possible to provide an image forming apparatus that supplies power to a DC load by an auxiliary power source, that is, a capacitor, and does not exceed the power that can be supplied from the power supply line even when the load changes suddenly. In addition, the power supply to the load by the capacitor is performed for a predetermined period. This predetermined period is determined by obtaining the necessary auxiliary power amount in advance and determining the capacity of the capacitor accordingly, so that the auxiliary power source can be controlled with simple control. Can be used efficiently.

  The image forming apparatus of the present invention is an image forming apparatus having a power supply device that supplies AC power and DC power to a load, the image forming apparatus having a capacitor charged with the DC power, and the capacitor being charged DC power is supplied to the load during a fixing reload period.

  As a result, a margin for the maximum supply power of the AC power line can be supplied to the fixing overheating device, so that the startup time of the device can be shortened.

  The “fixing reload period” in the present invention refers to a period from when the main power switch of the image forming apparatus is turned on to when the printing operation is started.

  The image forming apparatus of the present invention is an image forming apparatus having a power supply device that supplies AC power and DC power to a load, the image forming apparatus having a capacitor charged with the DC power, and the capacitor being charged DC power is supplied to the load for a predetermined period after the end of the fixing reload period.

  As a result, a margin for the maximum power supply of the AC power line can be supplied to the fixing heating device, so that it is possible to prevent the fixing temperature from dropping due to the sheet passing. Further, as a result, the conveyance speed can be improved.

  The image forming apparatus of the present invention is an image forming apparatus having a power supply device that supplies AC power and DC power to a load, the image forming apparatus having a capacitor charged with the DC power, and the capacitor being charged The DC power is supplied to the load during a fixing reload period and a predetermined period after the end of the fixing reload period.

  As a result, the temperature drop at the start of printing is suppressed and the reload temperature can be set low, so that the rise time can be further shortened.

  In the image forming apparatus of the present invention, the capacitor is an electric double layer capacitor.

  As a result, the running cost can be reduced and the power consumption can be reduced.

  According to the image forming apparatus of the present invention, it is possible to supply power even with a sudden change in load with a simple configuration.

  Embodiments of the present invention will be described below with reference to the drawings.

[Configuration of image forming apparatus]
FIG. 1 is a cross-sectional view showing a schematic configuration example of an image forming apparatus according to the present invention. An image forming apparatus 1 shown in FIG. 1 is a digital multi-function peripheral, and has a copying function, a printer function, a facsimile function, and the like. These functions can be sequentially switched and selected by an application switching key on an operation unit (not shown). When a copy function is selected, a copy mode is selected. When a printer function is selected, a printer mode and a facsimile function are selected. Sometimes the facsimile mode. The image forming apparatus 1 also includes an automatic document feeder (ADF) 10, an image reading device 20, an optical writing unit 30, a printer unit 40, and a capacitor unit 50.

The ADF 10 is a device that automatically sends a document placed thereon to the image reading device 20. The image reading device 20 is a device that reads image information of a document sent by the ADF 10. The optical writing unit 30 is a device that converts image information read by the image reading device 20 into optical information. The printer unit 40 is a device that transfers the same image as the read original document to a sheet based on the optical information converted by the optical writing unit 30. The photoconductor drum 111, the developing device 112, the transport belt 113, and the like. And a fixing device 114. The photosensitive drum 111 is an apparatus that forms an electrostatic latent image by being exposed with optical information from the optical writing unit 30. The developing device 112 is a device that develops an electrostatic latent image formed on the photosensitive drum 111 to form a toner image. The conveyor belt 113 is a device that transfers the toner image formed by the developing device 112 to a sheet. The fixing device 114 is a device that fixes the toner image transferred by the conveyance belt 113 and discharges the paper on which the toner image is fixed. The capacitor unit 50 is an auxiliary power source for the DC load of the image forming apparatus, and details will be described later.
[Operation of image forming apparatus]
Of the plurality of functions described above, the operation of the image forming apparatus 1 will be described using the copy mode as an example.

When a document bundle consisting of a plurality of documents is placed on the ADF 10, the ADF 10 sends the documents one by one to the image reading device 20 in order. The image reading device 20 reads image information of a sent document. Image information read by the image reading device 20 is corrected and processed by an image processing means (not shown), and then converted into optical information by the optical writing unit 30. This optical information exposes the photosensitive drum 111 uniformly charged by a charger (not shown), and as a result, an electrostatic latent image is formed. The electrostatic latent image formed on the photosensitive drum 111 is developed by the developing device 112 to become a toner image. This toner image is transferred onto a sheet by the conveyance belt 113 and fixed by the fixing device 114. Finally, the sheet on which the toner image is fixed is discharged from the fixing device 114.
[Configuration of power supply unit]
FIG. 2 is an example of a block diagram of a power supply unit of the image forming apparatus of FIG. The power supply unit of the image forming apparatus in FIG. 1 is connected to an AC power supply 61, and a main power switch 60, a main power supply unit 62, a capacitor charger 63, a capacitor 64, a capacitor converter 65, and a switching circuit 66. A + 5V system load 67a, first and second + 24V system loads 67b and 67c, a fixing heating device 68, and a control unit 70.

The main power switch 60 is a switch for turning on or off the power of the image forming apparatus. When the main power switch 60 is turned on, the image forming apparatus can receive power from the AC power supply 61. The main power supply unit 62 is a means for supplying power to each unit that executes the function of the image forming apparatus, and includes an AC / DC converter 62a and a fixing heater drive circuit 62b. The AC / DC converter 62a is means for converting AC power supplied from the AC power source 61 into DC power, and the converted DC power is supplied to each DC load. The fixing heater driving circuit 62 b is a circuit for driving the fixing heating device 68. The capacitor charger 63 is a circuit that converts AC power supplied from the AC power supply 61 into DC power, and charges the converted DC power in the capacitor 64. The capacitor 64 is an auxiliary power source for the image forming apparatus, and is composed of a large capacity capacitor such as an electric double layer capacitor. As the auxiliary power source, other than the electric double layer capacitor can be used, but in this embodiment, an electric double layer capacitor that can be charged and discharged in a short time and has a long life is used. The capacitor converter 65 is a means for adjusting the voltage so that the voltage discharged from the capacitor 64 becomes constant. Since the electric double layer capacitor used as the capacitor 64 has a feature that the voltage between its terminals becomes lower as it is discharged, it is necessary to provide a capacitor converter 65 after the capacitor 64 to make its output constant. There is. As the capacitor converter 65, any one of a step-up converter, a step-down converter, and a step-up / step-down converter is used according to the capacitor charging voltage and the lower limit voltage specification. The switching circuit 66 converts the power supplied to the second + 24V system load 67 c from the DC power converted by the AC / DC converter 62 a from the AC power supplied from the AC power supply 61 and the power charged in the capacitor 64. This is means for switching between DC power supplied via the capacitor converter 65. The + 5V system load 67a and the first and second + 24V system loads 67b and 67c are DC loads that are driven at 5V or 24V and execute the functions of the image forming apparatus. The fixing heating device 68 is a device for heating the fixing device 114 shown in FIG. 1, and is an AC load driven by AC power in this embodiment. The control unit 70 is a unit that controls the entire image forming apparatus, and also controls the operations of the fixing heater driving circuit 62b, the capacitor charger 63, the capacitor converter 65, and the switching circuit 66. Details of this control will be described later.
[Operation of power supply unit]
The operation of the power supply unit shown in FIG. 2 will be described.

  When the main power switch 60 is turned on, AC power is supplied from the AC power supply 61 to the main power supply unit 62 and the capacitor charger 63. A part of the AC power supplied to the main power supply unit 62 is converted into DC power by the AC / DC converter 62 a of the main power supply unit 62. The converted DC power is supplied directly to the + 5V system load 67a and the first + 24V system load 67b via the switching circuit 66 to the second + 24V system load 67c. The remaining AC power supplied to the main power supply unit 62 is supplied to the fixing heating device 68 via the fixing heater driving circuit 62b. On the other hand, AC power supplied to the capacitor charger 63 is converted into DC power by the capacitor charger 63. The converted DC power is charged in the capacitor 64.

The control unit 70 sequentially operates the DC loads 67a, 67b, and 67c according to each operation mode of the image forming apparatus that is a digital multifunction peripheral. Further, the control unit 70 controls the charging and discharging of the capacitor 64 by controlling the capacitor charger 63 and the capacitor converter 65, and at the time of starting the image forming apparatus and until a predetermined time elapses after starting. During this period, the power stored in the capacitor 64 is discharged. The electric power of the capacitor 64 is adjusted by the capacitor converter 65 so as to have a desired voltage value (+24 V in this embodiment). Further, at this time, the controller 70 switches the switching circuit 66 so that the power of the capacitor 64 is supplied to the second + 24V load. By supplying power from the capacitor 64 to the second + 24V load, there is a margin in the power supplied to the AC power supply 61. The controller 70 controls the fixing heater driving circuit 62 b and adds this margin to the power supplied to the fixing heating device 68. As a result, the power supplied to the fixing heating device 68 can be increased.
[Supply timing of auxiliary power]
FIG. 3 is a graph showing the transition of power consumption when the image forming apparatus of FIG. 1 is started up. The horizontal axis represents time, and the vertical axis represents the total power consumption of the apparatus. The dotted line is the power that can be supplied from the AC power supply. In FIG. 3, the rising period from immediately after the main power switch is turned on until the printing operation is started is “fixing reload period (1)”, and after the fixing reload period until a predetermined time elapses from the start of the printing operation. This period is referred to as “first operation period (2a)”, and the period after the elapse of a predetermined time is referred to as “second operation period (2b)”. The “printing operation” referred to here is an operation in which the toner image transferred onto the paper in FIG. 1 is fixed by the fixing device 114 and discharged. Further, the “predetermined time” referred to here is a time during which the DC load is transiently increased from the start of the printing operation.

  In the fixing reload period (1), in order to satisfy the start-up time required for the apparatus, more electric power is supplied to the fixing heating apparatus 68 in FIG. It is necessary to heat the device to a temperature that allows printing. Therefore, as shown in FIG. 3, the fixing power, which is the power supplied to the fixing heating device, is increased, but this increase is the total power consumption of the image forming apparatus including the power used in the DC load. Must not exceed the suppliable power of the AC power supply.

  In the first operation period (2a), since the temperature of the fixing device has reached a printable temperature, the fixing power for maintaining the temperature is smaller than that in the period (1). However, since the printing operation is started in the period (2a), the DC load is increased more than the period (1) due to the activation of the motor or the like, and the power used by the DC load is also increased. The image forming apparatus must be designed so that the total power consumption, which is the sum of the fixing power and the power used by the DC load, does not exceed the power that can be supplied from the AC power supply.

  The second operation period (2b) is a substantially stable use state. During this period, each load of the image forming apparatus is in a steady state, and no abrupt change occurs. Therefore, the total power consumption of the apparatus is sufficiently lower than the power that can be supplied from the AC power supply.

  When the image forming apparatus consumes power as described above, the power supply of the auxiliary power source, that is, the power supply of the capacitor 64 in FIG. 2 will be described for each period.

  In the fixing reload period (1), in order to further shorten the apparatus start-up time, it is necessary to further increase the fixing power. However, if the total power consumption of the device exceeds the suppliable power of the AC power supply indicated by the dotted line as a result of the increase in fixing power, the power supply of the AC power supply becomes less than the suppliable power and the system fails. Will be invited. Therefore, the power supply source to the second + 24V system load 67c, which is a part of the DC load, is switched to the capacitor 64, which is an auxiliary power source, and the margin for the suppliable power of the AC power supply 61 generated thereby is fixed. By supplying to the system, it is possible to further shorten the start-up time without breaking the system.

  In the first operation period (2a), as described above, the DC load increases due to the start of the motor or the like. Originally, the device must be designed to cope with this transient increase in DC load, but as a result of the increase in DC load, the total power consumption of the device is reduced to the suppliable power of the AC power source indicated by the dotted line. It may exceed. In that case, the power supplied from the AC power supply becomes less than the power that can be supplied, leading to the failure of the system. Therefore, as in the period (1), the power supply source to the second + 24V system load 67c, which is a part of the DC load, is switched to the capacitor 64, which is an auxiliary power source, and the power that can be supplied from the AC power supply 61 is thereby generated. It is possible to avoid the failure of the system by supplying a margin to the fixing heating device 68.

In the second operation period (2b), as described above, the total power consumption of the apparatus is sufficiently lower than the power that can be supplied from the AC power supply, so that the capacitor 64 is connected to the auxiliary power supply as in the periods (1) and (2a). It is not necessary to use as. Furthermore, there is a limit to the power that can be stored in the capacitor 64, and it is impossible to continuously supply power to the DC load. Accordingly, the power supply source of the DC load 67c is switched from the capacitor 64 to the main power supply unit 62, and the capacitor 64 itself is charged with the power supplied from the AC power supply via the capacitor charger 63.
[Modification 1]
In the description of the auxiliary power supply timing, the “fixing reload period (1)” and the “first operation period (2a)” in FIG. 3 are individually described, but power is supplied from the auxiliary power source to the DC load through both periods. It may be supplied. When power is supplied from the auxiliary power source to the DC load only during the fixing reload period (1), it is necessary to overheat the fixing device to a desired temperature in anticipation of a temperature drop of the fixing device that occurs during the printing operation. . However, if power is supplied from the auxiliary power source to the DC load in the first operation period (2a) following the fixing reload period (1), it is possible to suppress a decrease in the temperature of the fixing device at the start of the printing operation. Therefore, the heating temperature of the fixing device in the fixing reload period (1) can be set lower.

  In such a case, control of power supply by the control unit 70 of FIG. 2 will be described with reference to FIGS. 4 and 5.

  FIG. 4 is an example in which the functions performed by the control unit 70 of FIG. 2 are shown in blocks.

  In FIG. 4, the control unit 70 is a unit that controls the entire image forming apparatus, and includes an operation state confirmation unit 71, a charge / discharge control unit 72, a power source switching unit 73, a drive circuit control unit 74, and an elapsed time. Measuring means 75. The operation state confirmation unit 71 is a unit for confirming the operation state of the image forming apparatus, monitors the state of the main power switch and the fixing device, and receives an input signal from the operation unit. The charge / discharge control means 72 is means for controlling the capacitor charger 63 and the capacitor converter 65 so as to charge / discharge the capacitor 64 of FIG. The power supply switching unit 73 is a unit that switches the switching circuit 66 of FIG. 2. For example, (a) a predetermined period immediately after turning on the power or after returning from the off mode, (b) a fixing reload period, (c) a fixing reload period. The power supply source of the second + 24V system load 67c is switched from the main power supply unit 62 to the auxiliary power supply 64 in a predetermined period after the end, or (d) a fixing reload period and a predetermined period after the end of the fixing reload period. The drive circuit control means 74 is a means for controlling the fixing heater drive circuit 62b of FIG. 2, whereby the fixing power is switched according to each operation period. The elapsed time measuring means 75 is a means for measuring the elapsed time from the start of the printer.

  FIG. 5 is a flowchart of control of power supply by the control unit 70 of FIG.

  Immediately after the main power switch is turned on or when returning from the off mode, the operation state confirmation unit 71 confirms the operation state of the image forming apparatus in step S1. If it is determined in step S1 that it is necessary to execute a fixing reload operation (that is, a preparatory operation for fixing the toner image transferred onto the sheet by the fixing device 114 in FIG. 1), in step S2, The charge / discharge control means 72 controls the capacitor charger 63 and the capacitor converter 65, and the power supply switching means 73 controls the switching circuit 66 so that power supply from the capacitor 64 to the second + 24V system load 67c is started. Next, in step S <b> 3, the drive circuit control unit 74 adds the margin of the AC power supply generated as a result of the operation in step S <b> 2 to the power supplied to the fixing heating device 68, and supplies it to the fixing heating device 68. The fixing heater driving circuit 62b is controlled so as to increase the power supply. After the operation in step S3, the fixing device starts a fixing reload operation in step S4.

  The operation state confirmation unit 71 confirms whether or not the fixing reload operation has been completed in step S5. If it is determined that the operation has been completed, the operation state confirmation unit 71 further confirms the presence or absence of a print instruction from the operator in step S6. There is a print instruction, and the power to the fixing heating device supplied during the fixing reload operation is switched to the power required for the fixing operation (that is, the fixing power in the period (1) in FIG. 3 is changed to the fixing power in the period (2a)). In step S7, the drive circuit control means 74 controls the fixing heater drive circuit 62b so that the power is switched in that way. At this time, the switching circuit 65 remains switched so that the capacitor 64 supplies power to the second + 24V system load 67c. Next, the fixing device starts a printing operation in step S8.

  After the start of the printing operation, the elapsed time measuring means 75 starts measuring time in step S9 and confirms whether or not a predetermined time has elapsed in step S10. When the predetermined time has elapsed, in step S11, the drive circuit control means 74 switches the power to the fixing heating device supplied during the fixing operation to the power required for the normal printing operation (ie, as shown in FIG. 3). The fixing heater driving circuit 62b is controlled so that the fixing power in the period (2a) is switched to the fixing power in the period (2b). Next, in step S12, the power supply switching unit 73 switches the switching circuit 66 to switch the power supply source of the second + 24V system load 67c from the capacitor 64 to the AC / DC converter 62a of the main power supply unit. At this time, the capacitor converter 65 is stopped by the charge / discharge control means 72.

If there is no print instruction in S6 after the fixing reload operation, the operation moves to step S11, and the control device 70 operates to stop the power supply operation of the capacitor 64.
[Other variations]
In the description of the auxiliary power supply timing, a fixing reload period (1) in which a large amount of power is required for the fixing heating device and a period during which the DC load is transiently increased after the fixing reload period (that is, the first power supply) The operation period (2a)) has been described, but the same operation can be applied to periods other than these as long as they are specified periods in which a large amount of power is required for the fixing heating device. For example, the present invention can be applied to a system in which the power to the fixing heating device needs to be increased because the temperature of the fixing device drops due to paper passing when the printing operation is started after the fixing reload period. In this case, the “specified period” corresponds to a period until printing of a predetermined number of sheets is completed, and the capacity of the capacitor can be utilized to the maximum when a variable value with parameters such as paper size and room temperature is used as a parameter. .

  In the above-described embodiment, the load supplied with power from the capacitor 64 as the auxiliary power supply is the second + 24V system load 67c which is a part of the DC load. Alternatively, power may be supplied from an auxiliary power source to all DC loads. Furthermore, by providing a DC / AC converter after the capacitor 64, it is possible to supply power to the AC load.

  In the above-described embodiment, the capacitor charger 63 in front of the capacitor 64 is configured to be directly connected to the AC power supply 61. However, the capacitor charger 63 is provided after the AC / DC converter 62a of the main power supply unit. Also good. In that case, the capacitor charger may not have an AC / DC conversion function.

  In the embodiment described above, the fixing heating device 68 is an AC load driven by AC power, but may be a DC load driven by DC power, such as IH (Induction Heating) fixing. good. In this case, the fixing heater driving circuit 62 b that drives the fixing heating device 68 needs to be changed to have an AC / DC converter, and DC power needs to be supplied to the fixing heating device 68.

  Further, the capacitor unit of FIG. 1 (that is, the capacitor charger 63, the capacitor 64, and the capacitor converter 65 of FIG. 2) may be provided respectively or outside the image forming apparatus.

1 is a cross-sectional view illustrating a schematic configuration example of an image forming apparatus according to the present invention. FIG. 2 is an example of a block diagram of a power supply unit of the image forming apparatus in FIG. 1. FIG. 2 is a graph showing a transition of power consumption when the image forming apparatus of FIG. 1 is started up. It is the example which showed the function which the control part of FIG. 2 performs with the block. It is a flowchart of control of the electric power supply by the control part of FIG.

Explanation of symbols

1 Image forming apparatus 10 Automatic document feeder (ADF)
20 Image Reading Device 30 Optical Writing Unit 40 Printer Unit 50 Capacitor Unit 60 Main Power Switch 61 AC Power Supply 62 Main Power Supply Unit 62a AC / DC Converter 62b Fixing Heater Drive 63 Capacitor Charger 64 Capacitor 65 Capacitor Converter 66 Switching Circuit 67a + 5V System Load 67b, 67c + 24V system load 68 Fixing heating device 70 Control unit 71 Operating state confirmation unit 72 Charge / discharge control unit 73 Power supply switching unit 74 Drive circuit control unit 75 Elapsed time measurement time 111 Photosensitive drum 112 Developing device 113 Conveying belt 114 Fixing device

Claims (5)

In an image forming apparatus having a power supply device that supplies AC power and DC power to a load,
A capacitor charged with the DC power;
The image forming apparatus according to claim 1, wherein the DC power charged in the capacitor is supplied to the load for a predetermined period after the power is turned on or after returning from the off mode. In an image forming apparatus having a power supply device that supplies AC power and DC power to a load,
A capacitor charged with the DC power;
The DC power charged in the capacitor is supplied to the load during a fixing reload period. In an image forming apparatus having a power supply device that supplies AC power and DC power to a load,
A capacitor charged with the DC power;
The DC power charged in the capacitor is supplied to the load for a predetermined period after the fixing reload period ends. In an image forming apparatus having a power supply device that supplies AC power and DC power to a load,
A capacitor charged with the DC power;
The DC power charged in the capacitor is supplied to the load during a fixing reload period and a predetermined period after the end of the fixing reload period.   The image forming apparatus according to claim 1, wherein the capacitor is an electric double layer capacitor.

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