JP2007072008A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform optimum control without causing input current to exceed the rated current, by performing control in a combination of a main power source device, auxiliary power source device accumulatable power, and system capable of varying the supply of power to a fixing heating device. <P>SOLUTION: The image forming apparatus includes a fixing unit 17 of a heat fixing system; the main power source device 141 that supplies power to each load; and the auxiliary power source device that is capable of accumulating power and supplies DC power. The image forming apparatus is provided with a control section 120 for variably controlling the supply of power to the fixing unit 17. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a laser printer, a copying machine, a facsimile machine, and a multifunction machine. More specifically, the power control of the heat fixing device and the power supply to the device load are finely performed so as to suppress the power to a rated current or less. The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, in image forming apparatuses such as laser printers and copiers, a heat roll type in which a heating device such as a halogen heater or an induction coil is installed in or near a cylindrical fixing roller and the fixing roller is heated by the heat source. A fixing device is often used.

  In this method, an element (sensor) for temperature detection is arranged in the vicinity (or contact) of the fixing roller, and in the case of a heater, the heater driving element is turned on / off to control the temperature of the fixing roller surface to be stable. Is going. In the case of the induction heating method, the current input to the inverter is detected and the current applied to the coil is adjusted to control the temperature on the surface of the fixing roller to be stable. In recent years, the color and speed of image forming apparatuses have increased and the current consumption of drive systems has increased. However, there is a demand for energy saving and reduction of rated current from the market, and the rated current of the apparatus cannot be easily increased. . For this reason, the current that can be used in the fixing device is limited, and the power in the fixing device may be insufficient depending on the operation state of the device. In particular, MFPs (multifunction peripherals) with many peripheral devices often use a combination of systems. If a plurality of peripheral devices are installed, the input current increases and the above-described problem is likely to occur.

  From such a technical background, there has been disclosed a method for detecting the input current of the apparatus and varying the limit value of the current to the fixing heating apparatus (for example, see Patent Document 1). Further, there is disclosed a method for supplying power from the second power supply means so as to have a second power supply means capable of accumulating so that the input power does not exceed the rating of the AC line (for example, a patent). Reference 2).

JP-A-10-274901 JP 2004-236492 A

  In the conventional technology as described above, when the current (power) shortage as described above occurs, the current to the fixing heating device is limited during the image forming operation regardless of the state of the device. When the fixing temperature is lowered due to the shortage, the operation speed of the apparatus is often reduced to prevent the temperature of the fixing unit from decreasing. However, in the above method, the current to the fixing device is limited regardless of the state of the device, so that the frequency of the fixing temperature is reduced frequently, and the productivity is significantly reduced. Further, the method of Patent Document 1 requires a current detection circuit, which causes an increase in cost. Furthermore, the detection current needs to be set lower than the rated current in consideration of the delay of the detection time.

  In Patent Document 2, when an AC halogen heater is used as a fixing device, the AC halogen heater has a fixed power consumption, and it is difficult to accurately control the maximum input power. In Patent Document 2, the fixing power and the power control method of the power source are not clear.

  The present invention has been made in view of the above, and the input current is controlled by combining the main power supply device, the auxiliary power supply device that can be stored, and the system that can change the power supply to the fixing heating device. The purpose is to enable optimal control without exceeding the rated current.

  In order to solve the above-described problems and achieve the object, the invention according to claim 1 is a heat-fixing type fixing device, a main power supply device that supplies power to each load, and can store power and supply DC power. An image forming apparatus including an auxiliary power supply device that includes a control unit that variably controls power supply to the fixing device.

  According to the first aspect of the present invention, the input current is set to the rated value by performing control by combining the main power supply device, the auxiliary power supply device that can be stored, and the method that can change the power supply to the fixing heating device. Optimal control can be performed without exceeding, and the rise time can be shortened.

  The invention according to claim 2 is characterized in that the control means supplies power from the auxiliary power supply device to a part of the load in accordance with power supplied to the fixing device.

  According to the second aspect of the present invention, in the first aspect, more optimal control can be achieved by supplying current to a part of the load from the auxiliary power supply device in accordance with the operation state of the apparatus during the image forming operation. Thus, it is possible to suppress a decrease in productivity due to a decrease in linear velocity (photosensitive drum speed) or the like.

  According to a third aspect of the present invention, the control means limits the maximum value of power supply to the fixing device to a predetermined value or less when the stored power amount of the auxiliary power supply device is a predetermined value or less. It is characterized by doing.

  According to the third aspect of the present invention, in the first aspect, the control of the image forming apparatus is performed by performing control so as to temporarily limit the maximum value of the input current to the fixing device according to the heat storage state of the auxiliary power supply device. It is possible to avoid the occurrence of a stop or waiting time.

  The invention according to claim 4 is characterized in that the fixing device is an induction heating method.

  According to the fourth aspect of the present invention, in the first aspect, the amount of power supplied to the fixing device can be easily and accurately performed by using the induction heating method.

  The invention according to claim 5 is characterized in that the fixing device is a DC inverter system.

  According to the fifth aspect of the present invention, the amount of power supplied to the fixing heating device can be easily and accurately performed by using the DC inverter system in the first aspect.

  The invention according to claim 6 is characterized in that the auxiliary power supply device has power storage means of an electric double layer capacitor.

  According to the sixth aspect of the present invention, in the first aspect, by using the electric double layer capacitor as the heat storage means of the auxiliary power supply device, it is possible to extend the life of the auxiliary power supply and to rapidly charge the auxiliary power supply.

  In the image forming apparatus according to the present invention (Claim 1), the input current is rated by performing control by combining a main power supply, an auxiliary power supply that can be stored, and a system that can change the power supply to the fixing heating device. Optimum control can be performed without exceeding the value, and the rise time can be shortened.

  An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, wherein a current is supplied from the auxiliary power supply device to a part of the load according to the operation state of the apparatus during the image forming operation. It is possible to perform more optimal control and to suppress the decrease in productivity due to a decrease in linear velocity (photosensitive drum speed) or the like.

  According to a third aspect of the present invention, there is provided an image forming apparatus according to the first aspect, wherein control is performed so as to temporarily limit a maximum value of an input current to the fixing device according to a heat storage state of the auxiliary power supply device. There is an effect that it is possible to avoid the stop of the image forming apparatus and the occurrence of a waiting time.

  In addition, the image forming apparatus according to the present invention (Claim 4) has an effect that the amount of power supplied to the fixing device can be easily and accurately performed according to Claim 1 by using the induction heating method.

  In addition, the image forming apparatus according to the present invention (Claim 5) has an effect that the amount of power supplied to the fixing heating apparatus can be easily and accurately performed according to Claim 1 by using the DC inverter system. .

  According to a sixth aspect of the present invention, the image forming apparatus according to the first aspect of the present invention uses the electric double layer capacitor as a heat storage means of the auxiliary power supply device to extend the life of the auxiliary power supply and perform rapid charging. There is an effect that can be.

  Exemplary embodiments of an image forming apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment)
In the image forming apparatus such as a copying machine or a laser printer, the present invention performs control by combining a main power supply device and a system that can change the power supply to the auxiliary power supply device and the fixing heating device that can be stored. This achieves optimal control without exceeding the rated value and shortens the rise time of the image forming apparatus. This will be specifically described below.

  FIG. 1 is a block diagram showing a configuration relating to a power supply system of an image forming apparatus (digital copying machine) according to an embodiment of the present invention. In this figure, AC power supplied from an AC line 141 is converted to DC power by an AC / DC converter 142, and a part is directly supplied as power for each of + 24V and + 5V loads 147a, 147b and 147c. As the auxiliary power source, various types other than the electric double layer capacitor can be selected. In the present invention, an electric double layer capacitor that can be charged and discharged in a short time and has a long life is used. Further, as a characteristic of the electric double layer capacitor, the terminal voltage becomes lower as it is discharged, so that the output voltage is made constant by arranging the buck-boost converter (auxiliary power supply device) 145 after the electric double layer capacitor 144. I have to. In this embodiment, since the voltage is supplied to the + 24V system load 147b, the step-up / down converter 145 is configured to output + 24V.

  The switching circuit 146 includes a + 24V power generated by the AC / DC converter 142 based on the AC power supplied from the AC line 141, and a + 24V generated through the buck-boost converter 145 from the energy stored in the electric double layer capacitor 144. The power supply is switched according to control by the control unit 120 and supplied to the + 24V system load 147b. The control unit 120 also controls the entire digital copying machine, and operates the loads 147a to 147c sequentially according to each operation mode.

  The control unit 120 also controls charging / discharging of the electric double layer capacitor 144. In other words, the control unit 120 uses the AC / DC converter 142 when it determines that power can be supplied to all loads with the power supplied from the AC line 141 based on power consumption prediction as will be described later. The switching circuit 146 is switched so that the + 24V power source thus supplied is supplied to the + 24V system load 147b, and the electric double layer capacitor 144 is charged by controlling the charging circuit 143 for the margin. In addition, when the control unit 120 determines that the power supplied from the AC line 141 is insufficient to supply power to all loads, the control unit 120 converts the buck-boost converter from the energy accumulated in the electric double layer capacitor 144. The switching circuit 146 is switched so as to supply the + 24V power source generated through 145 to the + 24V system load 147b.

  In the image forming apparatus of the present invention, the control CPU in the control unit 120 determines the input power to the apparatus while controlling the temperature of the fixing heating apparatus. The power that can be consumed by the main power supply device is calculated from the input power to the fixing unit 122 via the fixing drive 121, and the required power in the main power supply device is calculated according to the system up state and each device operating state. When it exceeds the possible power, control is performed so that power is supplied from the auxiliary power device.

  In recent years, a DC inverter is used for the fixing driving device and a fixing heater is heated with a DC halogen heater, or an induction coil is installed in or near the roller, and an electric current is supplied to the coil using the inverter for the fixing driving device to heat the fixing device. Some devices are in control. In the case of these heating methods, it is possible to detect the output current of the inverter and accurately control the input current to the fixing device.

  FIG. 2 is an explanatory diagram showing the configuration of the image forming apparatus (digital copying machine) according to the embodiment of the present invention. In this figure, for a document bundle placed on the document table 2 with the image surface of the document on the document table 2 in the automatic document feeder (hereinafter referred to as ADF) 1, the print key 34 on the operation unit 30 is pressed. Then, the lowermost document is fed to a predetermined position on the contact glass 6 by the feeding roller 3 and the feeding belt 4. It has a counting function for counting up the number of originals upon completion of feeding one original. After the fed original is read by the reading unit 50 on the image data of the original on the contact glass 6, the original that has been read is discharged by the feeding belt 4 and the discharge roller 5. Further, when it is detected by the document set detection 7 that the next document is present on the document table 2, it is fed onto the contact glass 6 in the same manner as the previous document. The feeding roller 3, the feeding belt 4, and the discharging roller 5 are driven by a conveyance motor 26. The recording sheets stacked on the first tray 8, the second tray 9, and the third tray 10 are fed by the first paper feeding device 11, the second paper feeding device 12, and the third paper feeding device 13, respectively, and are conveyed longitudinally. The unit 14 is transported to a position where it abuts on the photosensitive drum 15. The image data read by the reading unit 50 is written on the photosensitive drum 15 by a laser from the writing unit 57 and passes through the developing unit 27 to form a toner image. The toner image on the photosensitive drum 15 is transferred while the recording paper is conveyed by the conveying belt 16 at the same speed as the rotation of the photosensitive drum 15. Thereafter, the image is fixed by the fixing unit 17 and is discharged by the paper discharge unit 18 to the finisher 70 of the post-processing apparatus.

  The fixing unit 17 includes a fixing roller having releasability, a pressure roller urged at a predetermined pressure facing the fixing roller, a halogen heater provided in an inner cylinder of the fixing roller, and a surface temperature of the fixing roller. Equipped with a thermistor, etc. The fixing unit 17 is not limited to the pressure / heating method of the fixing roller and the pressure roller, but may be a method using a fixing belt.

  The finisher 70 of the post-processing apparatus can usually guide the recording paper conveyed by the paper discharge roller 19 of the main body in the direction toward the paper discharge roller 72 and the direction toward the staple processing unit. By switching the switching plate 71 upward, the sheet can be discharged to the normal discharge tray 74 side via the transport roller 73. Further, by switching the switching plate 71 downward, the switching plate 71 can be conveyed to the staple table 78 via the conveying rollers 75 and 77. Each time a sheet of recording paper stacked on the staple table 78 is discharged, the paper end face is aligned by a paper alignment jogger 79, and is bound by the stapler 76 when a part of the copy is completed. The group of recording sheets bound by the stapler 76 is stored in the staple completion discharge tray 80 by its own weight. On the other hand, the normal paper discharge tray 74 is a paper discharge tray that can move back and forth. The paper discharge tray 74 that can be moved back and forth moves back and forth for each original or each copy section sorted by the image memory, and sorts copy paper that is simply discharged.

  When forming an image on both sides of the recording paper, the recording paper fed from each of the paper feed trays 8 to 10 is not guided to the paper discharge tray 74 side, and the branching claw for switching the path is on the upper side. Is once stocked in the duplex feeding unit 91. Thereafter, the recording paper stocked in the double-sided paper feeding unit 91 is re-fed from the double-sided paper feeding unit 91 to transfer the toner image formed on the photosensitive drum 15 again, and the branching claw for switching the path. Is set on the lower side and guided to the paper discharge tray 74. As described above, the duplex feeding unit 91 is used when creating images on both sides of the recording sheet. Further, when printing on the back side of the recording paper on which an image is placed, the double-sided paper feeding unit 91 is used to change the conveyance of the back side of the recording paper. The photosensitive drum 15, the conveyor belt 16, the fixing unit 17, the paper discharge unit 18, and the development unit 27 are driven by a main motor, and each of the paper feeding devices 11 to 13 is driven to transmit the driving of the main motor 25 by a paper feeding clutch. The The vertical conveyance unit 14 is driven to transmit the drive of the main motor by an intermediate clutch.

  Next, a process from reading a document to writing an image by the image forming apparatus will be described. The reading unit 50 includes a contact glass 6 on which an original is placed and an optical scanning system. The optical scanning system includes an exposure lamp 51, a first mirror 52, a lens 53, a CCD image sensor 54, and the like. Yes. The exposure lamp 51 and the first mirror 52 are fixed on a first carriage (not shown), and the second mirror 55 and the third mirror 56 are fixed on a first carriage (not shown). When reading a document image, the first carriage and the second carriage are mechanically scanned at a relative speed of 2 to 1 so that the optical path length does not change. This optical scanning system is driven by a scanner drive motor (not shown). The document image is read by the CCD image sensor 54, converted into an electrical signal, and processed. The writing unit 57 includes a laser output unit 58, an imaging lens 59, and a mirror 60. Inside the laser output unit 58, a polygon mirror (polygon mirror) that rotates at a high speed at a high speed by a laser diode that is a laser light source and a motor. ). The laser beam output from the writing unit 57 is applied to the photosensitive drum 15 of the image forming system. Although not shown, a beam sensor for generating a main scanning synchronization signal is disposed at a position where a laser beam near one end of the photosensitive drum 15 is irradiated.

Next, an example of variable control of power supply will be described. For example, the maximum current consumption of each unit is set as follows in the image forming apparatus shown in FIG.
Current consumption in power supply during standby: 0.5A
Current consumption in scanner / ADF during image reading: 1.0A
Current consumption during operation of finishers and other post-processing devices: 1.0 A
Current consumption during paper feed / image creation during image creation: 3.0A
Current consumption in fixing device: 5.0 to 11.0 A
Rated (allowable) current (Io) of the device: 15.0A

  Thus, when all the loads of the apparatus are operated simultaneously, the current consumption is 16.5A, exceeding the rated current Io of the apparatus: 15A. Therefore, in the present invention, when the peripheral devices such as the ADF and the post-processing device are connected as described above, and the maximum current of the device may be the rated current of the device, the input current of the device is adjusted to the supply current to the fixing device. Auxiliary power supply and switching circuit 146 are controlled so that does not exceed the rated current.

  FIG. 3 is a flowchart showing an example of power control in the digital multi-function peripheral according to the embodiment of the present invention. Here, an example of the operation using the block diagram of FIG. 1 and the current set value will be described. This control is executed by the control unit 120. In FIG. 3, first, the system state of the apparatus is confirmed (step S11).

in this case,
(1) Maximum current in case of full system: 16.5A
(2) Maximum current when no finishing device such as a finisher is attached: 15.5 A
It becomes.

  Subsequently, it is determined whether or not the maximum current is over (step S12). If it is determined that the maximum current is over, it is further determined whether or not the printing operation is being performed (step S13).

  In step S13, in the case of the print mode, it is confirmed whether the mode uses a post-processing device such as a sorter / finisher. Next, the system power is calculated by checking whether the reading mode uses the ADF 1 or the scanner. At the same time, the power supplied to the fixing unit 17 is calculated from the surface temperature of the fixing roller (step S14).

For example,
[1] Maximum power when all devices operate in a full system: 16.5A
[2] Maximum power when print mode image reading does not occur: 15.5A
[3] Maximum power in the print mode and when the post-processing device does not operate or the post-processing device is not mounted: 14.5 A

  Subsequently, it is determined whether or not the current is over (step S15). If it is determined that the current is over, it is further determined whether or not the auxiliary power source (electric double layer capacitor 144) is operable (step S16). If the auxiliary power source is operable, the auxiliary power source is turned off. Operates (step S17).

  That is, in the case of [1] and [2] above, the control unit 120 exceeds the current limit value, so the auxiliary power supply (electric double layer capacitor 144) and the switching circuit 146 are controlled to reduce the power of the main power supply device. By doing so, control is performed so that the rated current of the device is not exceeded. When the amount of stored power is reduced and power cannot be supplied from the auxiliary power source, the upper limit of power supply to the fixing unit 17 (fixing heating device) is limited. In the example of [1], it is 9.5 A, and in the example of [2], it is 10.5 A. If the temperature drops below the set value due to the limitation of the fixing current, or if the auxiliary power source cannot be used due to insufficient charging, the printing speed is reduced. Alternatively, it is possible to cope with the problem by increasing the reading interval or accumulating the received facsimile data / print data in the memory and stopping the image forming operation during reading.

  Further, power is supplied to the fixing heating device through an inverter. This makes it possible to control the fixing power more accurately, so that the output of the auxiliary power supply device can be reduced, and the capacity of the storage means can be reduced and the life can be extended.

  In addition, the 24V system load 147b that supplies power from the auxiliary power supply device can be similarly reduced in the capacity of the storage means and extended in life by being a load with a low operation frequency during printing such as a scanner.

  Therefore, according to the embodiment described above, the input current is rated by performing control by combining the main power supply device, the auxiliary power supply device that can be stored, and the method that can change the power supply to the fixing heating device. Optimal control can be performed without exceeding the value, and the rise time can be shortened.

  In addition, more optimal control can be performed by supplying current to some loads from the auxiliary power supply device according to the operation state of the apparatus during the image forming operation, and the linear speed (photosensitive drum speed) can be reduced. It becomes possible to suppress a decrease in productivity due to a decrease or the like.

  Further, by controlling so as to temporarily limit the maximum value of the input current to the fixing unit 17 according to the heat storage state of the auxiliary power supply device, it is possible to avoid the stoppage of the device and the occurrence of waiting time.

  Further, by using the induction heating method, it becomes possible to easily and accurately supply the power to the fixing unit 17 (fixing heating device).

  In addition, by using the DC inverter system, it is possible to easily and accurately supply the power to the fixing heating device.

  Further, by using an electric double layer capacitor as the heat storage means of the auxiliary power supply device, it is possible to extend the life of the auxiliary power supply and to rapidly charge it.

  As described above, the image forming apparatus according to the present invention is useful for laser printers, copiers, and facsimile machines, and in particular, the power supply to the main power supply device, the auxiliary power supply device that can be stored, and the fixing heating device can be changed. This method is suitable for devices and systems that control the input current without exceeding the rated value.

1 is a block diagram showing a configuration relating to a power supply system of an image forming apparatus (digital copying machine) according to an embodiment of the present invention. 1 is an explanatory diagram showing a configuration of an image forming apparatus (digital copying machine) according to an embodiment of the present invention. 5 is a flowchart illustrating an example of power control in the digital multi-function peripheral according to the embodiment of the present invention.

Explanation of symbols

17 Fixing unit 120 Control unit 121 Fixing drive 141 Main power supply 142 AC / DC converter 143 Charging circuit 144 Electric double layer capacitor 145 Buck-boost converter 146 Switching circuit 147a + 24V system load 147b + 24V system load 147c + 5V system load

Claims (6)

In an image forming apparatus comprising: a heat-fixing type fixing device; a main power supply device that supplies power to each load; and an auxiliary power supply device that can store power and supplies DC power.
An image forming apparatus comprising control means for variably controlling power supply to the fixing device.   The image forming apparatus according to claim 1, wherein the control unit supplies power to the partial load from the auxiliary power supply device in accordance with power supplied to the fixing device.   2. The control unit according to claim 1, wherein when the stored power amount of the auxiliary power supply becomes a predetermined value or less, the control unit limits a maximum value of power supply to the fixing device to a predetermined value or less. The image forming apparatus described.   The image forming apparatus according to claim 1, wherein the fixing device is an induction heating method.   The image forming apparatus according to claim 1, wherein the fixing device is a DC inverter type.   The image forming apparatus according to claim 1, wherein the auxiliary power supply device includes power storage means of an electric double layer capacitor.

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