JP3898168B2 - Auxiliary power supply and image forming apparatus - Google Patents

Description

  The present invention relates to an auxiliary power supply for heating various materials and apparatuses, and image forming apparatuses such as copying machines, printers, and facsimile machines using an electrophotographic system, and particularly to improvement of safety.

  An image forming apparatus such as a copying machine or a printer forms an image on a recording medium such as plain paper or OHP. This image forming apparatus employs an electrophotographic system in view of high speed image formation, image quality, cost, and the like. The electrophotographic method is a method in which a toner image is formed on a recording medium, and the formed toner image is fixed on the recording medium with heat and pressure. The heat roller method is currently the most widely used fixing method from the standpoint of safety. Has been. In the heat roller system, a fixing roller heated by a heat generating member such as a halogen heater and a pressure roller disposed opposite to the fixing roller are pressed to form a mutual pressure contact portion called a nip portion, and a toner image is formed in the nip portion. This is a method of heating through a recording medium to which is transferred.

  In recent years, environmental problems have become important and image forming apparatuses such as copiers and printers have been saving energy. In considering the energy saving of this image forming apparatus, what cannot be ignored is the power saving of the fixing device for fixing the toner to the recording medium. In order to reduce the power consumption of the fixing device during standby of the image forming apparatus, the temperature of the fixing roller is maintained at a constant temperature slightly lower than the fixing temperature during standby, so that the temperature can be immediately raised to a usable temperature during use. The temperature of the fixing roller is not waited for. In this case, even when the fixing device is not used, a certain amount of power is supplied to consume extra energy. It is said that the energy consumption during standby increases from about 70% to 80% of the energy consumption of the device.

  It is desired to further reduce power consumption by reducing energy consumption during standby. When energy consumption is reduced to zero during standby in the image forming device, the fixing roller of the fixing device mainly uses a metal roller such as iron or aluminum, and since the heat capacity is large, the temperature is raised to a usable temperature of about 180 ° C. In order to do so, a long heating time such as several minutes to several tens of minutes is required, and the usability of the user is deteriorated. For this reason, a configuration in which the temperature of the fixing roller is quickly raised is necessary for realizing an energy-saving copying machine. For example, as shown in Patent Document 1 and Patent Document 2, an auxiliary power supply device during standby of the fixing device When the fixing device is started up, power is supplied from the main power supply device and the auxiliary power supply device to shorten the rise time.

As shown in Patent Document 1 and Patent Document 2, by providing an auxiliary power supply device having a large-capacity capacitor, the fixing device can be heated to a target temperature in a short time. When maintaining the auxiliary power supply or removing and replacing the auxiliary power supply, if the capacitor included in the auxiliary power supply is in a charged state, there may be a risk of electric leakage or electric shock, and safety measures are taken. It wasn't.
JP 2000-315567 A JP 2002-280146 A

  The present invention improves such disadvantages, and when maintaining the device main body or removing the auxiliary power supply device from the device main body, the electric power stored in the auxiliary power supply device is prevented from being output to the outside, and there is a risk of electric shock or the like. It is an object of the present invention to provide an auxiliary power supply device that can be eliminated or display the amount of electric power charged to improve safety for an operator or a user, and an image forming apparatus using the auxiliary power supply device.

  An auxiliary power supply device of the present invention is an auxiliary power supply device that is detachably provided in an electric device main body, and stores an electric power supplied from the main power supply device, and an electric storage element that supplies the stored electric power to another element; Control means for intermittently transferring power between the power storage element and another element, and the control means shuts off the power supplied to the electric device body, and the power storage element and the other element. It is characterized in that the connection between and is cut off and the cut-off state is maintained.

  The auxiliary power supply device has a discharging means for consuming the power stored in the power storage element, and the control means uses the power stored in the power storage element as the discharging means when the power supplied to the electric device body is shut off. It is preferable to discharge the electric power stored in the power storage element to a dangerous voltage or less.

  Further, when maintaining the auxiliary power supply device, it is desirable that the control means discharges the power stored in the power storage element to the discharge means so that the power stored in the power storage element is less than the dangerous voltage.

  Further, when the auxiliary power supply device is removed from the electric device main body, the control means disconnects the connection between the power storage element and the other elements and maintains the disconnected state, or discharges the power stored in the power storage element. It is desirable that the electric power discharged to the means and the electric power stored in the electric storage element be made lower than the dangerous voltage.

  In addition, the amount of charge of the power storage element may be displayed on the display means to notify the danger of electric shock.

  It is preferable to use an electric double layer capacitor as the electric storage element so that it can be charged in a short time and discharged with a large amount of power in a short time.

  The image forming apparatus according to the present invention includes the auxiliary power supply and supplies power to the fixing device from the auxiliary power supply.

  This invention stores an electric power supplied from a main power supply device, and an auxiliary power supply device having a power storage element that supplies the stored electric power to other elements is mounted on the electric device main body, and cuts off the electric power supplied to the electric device main body. In this case, by blocking the connection between the power storage element and other elements and maintaining the shut-off state, it is possible to prevent the amount of power stored in the power storage element from greatly decreasing and prevent leakage or electric shock. It is possible to improve safety.

  Also, when the power supplied to the electrical device main body is cut off, the power stored in the power storage element is discharged inside the auxiliary power supply device so that the power stored in the power storage element falls below the dangerous voltage, for maintenance etc. In addition, it is possible to prevent an electric shock with the electric power stored in the power storage element, and to improve safety.

  Further, when the auxiliary power supply device is removed from the main body of the electric equipment, the connection between the power storage element and other elements is interrupted to maintain the shut-off state, or the power stored in the power storage element is transferred to the interior of the auxiliary power supply device. Therefore, the electric power stored in the electric storage element can be reduced to a dangerous voltage or less to prevent electric shock during maintenance or transportation, and safety can be ensured.

  In addition, the amount of charge of the power storage element is displayed to notify the danger of electric shock, thereby improving safety.

  By using an electric double layer capacitor as this electricity storage element, it can be charged in a short time, has a long life and can discharge a large amount of power in a short time, and further enhances safety even when charging continues. be able to.

  By mounting the auxiliary power supply device on the image forming apparatus and supplying power from the auxiliary power supply device to the fixing device, it is possible to improve safety when maintaining the image forming apparatus.

  FIG. 1 is an external view of an image forming apparatus according to the present invention. As shown in the figure, an electrophotographic image forming apparatus 1 includes a main body 2 that performs a copying operation, a paper feeding device 3 that stores a large amount of recording paper, and supplies the stored recording paper to the main body 2. The finisher 4 performs sorting, punching, binding, and the like on the copied paper and the like, and the paper discharge unit 5 that discharges the recording paper that has been copied and sorted. The main body 2 has an automatic document feeder 6 and an operation unit 7 at the top, and a paper feed unit 8 at the bottom. The automatic document feeder 6 conveys the set document so as to pass through the reading position of the main body 2. The operation unit 7 includes a display panel for displaying various information, buttons for inputting various instructions, and the like, and a power switch. When the power switch is turned on, the drive power is supplied from the main power supply device to the main body 2 and the sheet feeding device 3 of the image forming apparatus 1 to be in an operating state, and is supplied from the main power supply device by turning off the power switch. The driving power that is being cut is cut off, and the operation of the main body 2 and the like is stopped. The paper supply unit 8 stores recording paper, an OHP sheet, and the like, and sends the stored recording paper to the main body unit 2 to form an image.

  As shown in the block diagram of FIG. 2, the main body 2 is disposed along the scanner unit 10, the writing unit 11, and the transfer belt 12, and includes C (cyan), M (magenta), Y (yellow), and Bk. It has four sets of photoconductor units 13 that form four-color images such as (black) and a fixing unit 14 provided on the downstream side in the conveyance direction of the transfer belt 12. The photoconductor unit 13 includes a photoconductor 15, a charging unit 16, a developing unit 17, a transfer unit 18, and a cleaning unit 19 provided along the photoconductor 15. The scanner unit 10 irradiates light on a document placed on a platen glass or a document sent from the automatic document feeder 6, and photoelectrically converts the reflected light to read an image of the document. The writing unit 11 writes the image by irradiating the photoconductor 15 with a laser beam corresponding to the image read by the scanner unit 10.

  When an image is formed by the main body 2 of the image forming apparatus 1, the surface of the rotating photoreceptor 15 of each photoreceptor unit 13 is uniformly charged by the charging unit 16, and the writing unit 11 responds to the image information. The emitted laser light is incident on the surface of the charged photoconductor 15 to form an electrostatic latent image corresponding to the image to be formed. The electrostatic latent image formed on the surface of the photoconductor 15 is developed in four colors such as C (cyan), M (magenta), Y (yellow), and Bk (black) by the developing unit 17 of each photoconductor unit 13. To form a toner image. The toner images formed on the photoconductors 15 of the photoconductor units 13 are sequentially superimposed and transferred by the transfer unit 18 onto, for example, a recording sheet conveyed by the transfer belt 12. The recording sheet on which the toner image is transferred is conveyed to the fixing unit 14. After the toner image is transferred to the recording paper, the toner remaining on the photoreceptor 15 is removed by the cleaning unit 19.

  The fixing unit 14 includes a fixing roller 20 and a heating roller 21. As shown in FIG. 3, a plurality of heating elements 22 to 24 and an auxiliary heating element 25 are arranged in the hollow portion of the fixing roller 20, and power is supplied to the heating elements 22 to 24 and the auxiliary heating element 25. The surface temperature of the fixing roller 20 is heated to a constant temperature. When the recording paper on which the toner image is transferred passes between the fixing roller 20 and the pressure roller 21 at which the surface temperature becomes a constant temperature, the toner image is fixed on the recording paper by being heated and pressurized.

  The power supply device 30 that supplies power to the heating elements 22 to 24 and the auxiliary heating element 25 of the fixing roller 20 supplies power supplied from the main power supply device 31 to the heating elements 22 to 24 as shown in the circuit diagram of FIG. Switches 32 to 34 that are turned on / off, an auxiliary power supply device 35 that supplies power to the auxiliary heating element 25, and a temperature detection unit 36 that detects the temperature of the fixing roller 20 heated by the heating elements 22 to 24 and the auxiliary heating element 25. And a control unit 37. The control unit 37 includes a CPU, a memory, and the like, and controls on / off of the switches 32 to 34 so that the temperature of the fixing roller 20 detected by the temperature detection unit 36 becomes a predetermined constant temperature. At the same time, the operation of the auxiliary power supply 35 is controlled. A control voltage is applied to the control unit 37 while the main power supply device 31 is on even when the power switch 71 of the operation unit 7 is off.

  The auxiliary power supply device 35 includes a power storage element 38, a charger 39, a remaining voltage detection unit 40, a charging switch 41, and a changeover switch 42. The electric storage element 38 uses an electric double layer capacitor that does not involve a chemical reaction. By using an electric double layer capacitor for this electricity storage element 38, it can be charged in a short time, can have a long life, and can discharge a large amount of power in a short time. Can be increased.

  That is, when a secondary battery of a general nickel-cadmium battery is used as the storage element 38, the charging time takes several hours even if rapid charging is performed, but when an electric double layer capacitor is used, it takes about several minutes. Can be recharged. Therefore, charging / discharging is possible frequently, and the frequency | count of supplying electric power to the auxiliary heat generating body 25 within the same time can be increased. Nickel-cadmium batteries have a short life because the number of charge / discharge cycles is 500 to 1000, and there is a problem in replacement time and cost. However, electric double layer capacitors have a long life as an auxiliary power source and a memory effect. Therefore, there is little deterioration due to repeated charge and discharge, and this is particularly advantageous for the heating device that repeats the non-heating state during standby and the heating state during use, and the fixing roller 20 of the image forming apparatus 1. Moreover, since lead exchange batteries do not require liquid replacement or replenishment, maintenance is almost unnecessary. In addition, since the secondary battery cannot discharge the stored power at once, the fixing unit 14 cannot supply a large amount of power when starting up from a low temperature, and the effect of reducing the start-up time is not so much. When an electric double layer capacitor is used, a large amount of power can be discharged in a few seconds, and the start-up time of the fixing unit 14 can be greatly shortened. In addition, since the secondary battery uses a chemical reaction, if it is not necessary to discharge after charging to the maximum capacity, the container will expand due to gas generated by the chemical reaction, etc. if it is connected to the charging circuit. While there is a danger of explosion, the electric double layer capacitor uses a physical phenomenon rather than a chemical reaction, so there is no gas generation and it is safe to continue charging.

  In this way, products having excellent characteristics of electric double layer capacitors and capable of storing a large amount of electric energy have been developed in recent years, and some of them are being studied for use in electric vehicles and the like. For example, an electric double layer capacitor developed by Nippon Chemi-Con Co., Ltd. has a capacitance of about 2000 F, and has a sufficient capacity for supplying power for several seconds to several tens of seconds. A capacitor of about 80 F is also sold by NEC Corporation under the trade name Hypercapacitor.

  The charger 39 charges the power storage element 38 using the electric double layer capacitor. The remaining voltage detection unit 40 detects the charging voltage of the storage element 38 and outputs it to the control unit 37. The charge switch 41 turns on / off the power supplied from the main power supply 31 to the charger 39. The changeover switch 42 switches between charging the power storage element 38 and supplying power from the power storage element 38 to the auxiliary heating element 25. The operation of the charging switch 41 and the changeover switch 42 is controlled by the control unit 37.

  With reference to the flowchart of FIG. 5, the operation of supplying power to the heating elements 22 to 24 and the auxiliary heating element 25 of the fixing roller 20 and charging the storage element 38 of the auxiliary power supply 35 with this power supply device 30 will be described. To do.

  When the power switch 71 of the operation unit 7 is turned on (step S1), the control unit 37 inputs the temperature of the fixing roller 20 detected by the temperature detection unit 36 (step S2) and is preset in the memory. The detected temperature is subtracted from the target temperature to obtain a temperature difference between the target temperature and the current temperature of the fixing roller 20 (step S3). The control unit 37 compares the obtained temperature difference with a preset threshold value (step S4), and when the obtained temperature difference is smaller than the threshold value, that is, the fixing roller 20 has been heated to substantially the same temperature as the target temperature. If so, the process proceeds to a standby process (step S5).

  If the obtained temperature difference is larger than the threshold value, the switches 32 to 34 are turned on to supply power from the main power supply 31 to the heating elements 22 to 24 to heat the fixing roller 20 and switch the auxiliary power supply 35. The switch 42 is connected to the auxiliary heating element 25 side, and the electric double layer capacitor of the electricity storage element 38 is discharged to supply power to the auxiliary heating element 25 (step S6). As described above, when the heating elements 22 to 24 and the auxiliary heating element 25 are heated by supplying power, the control unit 37 inputs the temperature of the fixing roller 20 detected by the temperature detection unit 36 to fix the heating. It is determined whether or not the temperature of the roller 20 has reached the target temperature (step S7). If the result of this determination is that the temperature of the fixing roller 20 has not reached the target temperature, the controller 37 continues to supply power to the heating elements 22 to 23 and the auxiliary heating element 25 (step S6). Further, when the temperature of the fixing roller 20 reaches the target temperature, the control unit 37 shifts to a standby process (step S5).

  If it transfers to a standby process, the control part 37 will cancel | release the connection with respect to the auxiliary heating element 25 side of the changeover switch 42 of the auxiliary power supply device 35 connected to the auxiliary heating element 25 side. Then, the switches 32 to 34 are on / off controlled so that the temperature of the fixing roller 20 detected by the temperature detection unit 36 maintains the target temperature (step S8). In this state, the control unit 37 inputs the charging voltage of the power storage element 38 detected by the remaining voltage detection unit 40 of the auxiliary power supply device 35 and displays it on the display panel 72 of the operation unit 7 (step S9). Compared with the set reference value (step S10), when the charging voltage of the power storage element 38 is equal to or lower than the reference value and no power is supplied to the three heating elements 22 to 24 (step S11), the charge switch 41 is turned on, and the changeover switch 42 is connected to the charger 39 side to supply power from the main power supply 31 to the charger 39 to charge the storage element 38 (step S12). When this power storage element 38 is being charged, when the charging voltage of the power storage element 38 detected by the residual voltage detection unit 40 exceeds the reference value (step S13), power is supplied to the heating elements 22-24. When the switches 32 to 34 are turned on (step S14), the control unit 37 turns off the charging switch 41 and releases the connection of the changeover switch 42 to the charger 39 side to stop charging the storage element 38 (step S14). S15).

  Thus, after the power switch 71 is turned on, if the difference between the current temperature of the fixing roller 20 and the target temperature is larger than the threshold value, for example, the detected temperature of the fixing roller 20 is 28 ° C. while the target temperature is 180 ° C. The temperature difference is as large as 152 ° C., for example, when there is a large difference from the threshold of 30 ° C., power is supplied to the auxiliary heating element 25 in addition to the three heating elements 22 to 24 Since the roller 20 is heated, the fixing roller 20 can be heated to the target temperature of 180 ° C. in a short time. On the other hand, when the difference between the target temperature and the current temperature is not so large, for example, when the temperature of the fixing roller 20 is 150 ° C. or higher, the difference from the target temperature is 30 ° C. or lower, so only the three heating elements 22 to 24 are used. The temperature can be raised to the target temperature in a sufficiently short time. Therefore, in this case, it is not necessary to supply power to the auxiliary heating element 25. When the temperature of the fixing roller 20 reaches the target temperature and power is not supplied to the heating elements 22 to 24, power is supplied to the auxiliary heating element 25. Can be charged.

  As shown in the flowchart of FIG. 6, the control unit 9 constantly monitors the operating state of the power switch 71 while the main power supply 31 of the image forming apparatus 1 is on, and when the power switch 71 is turned off (step) S21), power supply to loads other than the auxiliary power supply device 35, such as the heating elements 22 to 24, the main body 2 and the like, is cut off (step S22). Then, the changeover switch 42 of the auxiliary power supply 35 is not connected to either the charger 39 side or the auxiliary heating element 25 side, so that the storage element 38 is disconnected from the auxiliary heating element 25 or the charger 39 ( Step S23). When it is confirmed that the changeover switch 42 is not connected to either the charger 38 or the auxiliary heating element 25 (step S24), the main power supply 31 that supplies power to the entire image forming apparatus 1 is turned off (step S24). S25).

  Thus, when the power switch 71 is turned off, the main power supply device 31 is not immediately turned off, the power storage element 38 is not connected to either the charger 39 or the auxiliary heating element 25, and the power storage element 38 is not charged or discharged. Since the main power supply device 31 is turned off after confirming that it is in the state, the power stored in the power storage element 38 is prevented from leaking to the other while the main power supply device 31 is turned off. Therefore, even if the main power supply device 31 is turned off for a long period of time, it is possible to prevent the amount of power stored in the power storage element 38 from greatly decreasing. Further, even when a maintenance person or the like performs maintenance on the main body 2 of the image forming apparatus 1 for maintenance or the like, the power transfer between the power storage element 38 and other elements is interrupted. Therefore, electric shock and the like can be prevented, and work safety can be improved. Furthermore, since the charge amount of the power storage element 38 is displayed on the display panel 72, the charge amount of the power storage element 38 can be confirmed, and the safety of work can be improved more reliably.

  In the above description, the case where the main power supply 31 is turned off by the control unit 37 when the power switch is turned off has been described. However, the main power supply 31 is turned on and the auxiliary power supply 35 is operated for maintenance or the like. When performing, there is a risk of electric shock if a maintenance staff or the like touches the power storage element 38 having a large amount of charge. Therefore, as shown in the circuit diagram of FIG. 7, the auxiliary power supply 35 is provided with a discharge unit 45 having a discharge load 46 and a discharge switch 47, and the control unit 37 turns on the discharge switch 47 during maintenance. At the same time, it is preferable to connect the changeover switch 42 to the discharge unit 45 side to discharge the electric power charged in the electric storage element 38 to the discharge load 46 so that the electric power charged in the electric storage element 38 is lower than the dangerous voltage. . Thus, safety can be further improved by discharging the electric power charged in the power storage element 38 within the auxiliary power supply device 35 so as to be below the dangerous voltage.

  Further, when the auxiliary power supply 35 is removed from the image forming apparatus 1 for maintenance or the like, there is a risk that the changeover switch 42 of the auxiliary power supply 35 may come into contact with the charger 39 or the connection terminal side of the auxiliary heating element 5 due to vibration at that time. There is sex. Therefore, as shown in the circuit diagram of FIG. 8, the auxiliary power supply 35 is provided with a cutoff setting unit 43 having an attachment / detachment detection unit 44, and the attachment / detachment detection unit 44 detects that the auxiliary power supply 35 has been removed from the image forming apparatus 1. When this occurs, the cutoff setting unit 43 keeps the changeover switch 42 from contacting the charger 39 or the connection terminal side of the auxiliary heating element 5. In this way, power transfer between the power storage element 38 and other elements can be forcibly cut off during maintenance or transportation, preventing electric shock and improving work safety. it can.

  Further, as shown in the circuit diagram of FIG. 9, a discharge switch 47 is connected to the auxiliary power supply 35 between the cutoff setting unit 43, the connection between the changeover switch 42 and the storage element 38, and the discharge load 46. When the auxiliary power supply 35 is removed from the image forming apparatus 1 when the discharge unit 45 is provided, the cutoff setting unit 43 keeps the changeover switch 42 from contacting the charger 39 or the connection terminal side of the auxiliary heating element 5. Then, it is preferable to turn on the discharge switch 47 of the discharge unit 45 in the cutoff setting unit 43 to discharge all the electric power charged in the power storage element 38 to the discharge load 46. In this way, safety can be further improved.

  In the above description, the case where the charge amount charged in the power storage element 38 of the auxiliary power supply device 35 is displayed on the display panel 72 of the image forming apparatus 1 has been described. The charge amount may be displayed by the device 35 itself.

1 is an external view of an image forming apparatus according to the present invention. 2 is a configuration diagram of a main body of the image forming apparatus. FIG. It is sectional drawing which shows the structure of a fixing roller and a pressure roller. FIG. 3 is a circuit diagram illustrating a configuration of a power supply device that heats a fixing roller. It is a flowchart which shows the heat processing by a power supply device. It is a flowchart which shows a process when a power switch is turned off. It is a circuit diagram which shows the structure of a 2nd power supply device. It is a circuit diagram which shows the structure of a 3rd power supply device. It is a circuit diagram which shows the structure of a 4th power supply device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Image forming apparatus, 2; Main-body part, 3; Paper feeder, 5; Paper discharge part, 6: Automatic document feeder,
7; operation unit, 10; scanner unit, 11; writing unit, 13; photoconductor unit,
14; fixing unit, 20; fixing roller, 21; heating roller, 22 to 24; heating element,
25; auxiliary heating element, 30; power supply, 31; main power supply, 32-34; switch,
35; auxiliary power supply device, 36; temperature detection unit, 37; control unit, 38;
39; Charger; 40; Residual voltage detection unit; 41; Charge switch; 42;

Claims (8)

An auxiliary power supply device detachably provided in the electric device main body,
A power storage element that stores power supplied from the main power supply device and supplies the stored power to another element; and a control unit that intermittently transfers power between the power storage element and the other element; When the power supplied to the electric device main body is cut off, the control means cuts off the connection between the power storage element and another element and maintains the cut-off state.   Discharging means for consuming electric power stored in the electric storage element, and the control means discharges electric power stored in the electric storage element to the discharging means when the electric power supplied to the electric device main body is cut off. The auxiliary power supply apparatus according to claim 1, wherein the power stored in the power storage element is set to a dangerous voltage or less.   3. The auxiliary device according to claim 2, wherein, when maintaining the auxiliary power supply device, the control unit discharges the electric power stored in the power storage element to the discharge unit, and sets the power stored in the power storage element to a dangerous voltage or less. Power supply.   4. The device according to claim 1, wherein when the auxiliary power supply device is removed from the electric device main body, the control unit cuts off the connection between the power storage device and another device and maintains the cut-off state. Auxiliary power supply as described.   When the auxiliary power supply device is removed from the electric device main body, the control means discharges the electric power stored in the electric storage element to the discharging means, so that the electric power stored in the electric storage element falls below a dangerous voltage. The auxiliary power supply device according to claim 2 or 3.   The auxiliary power supply device according to claim 1, further comprising display means for displaying a charge amount of the power storage element.   The auxiliary power supply device according to claim 1, wherein the power storage element is an electric double layer capacitor. An image forming apparatus comprising the auxiliary power supply device according to claim 1, wherein power is also supplied from the auxiliary power supply device to the fixing device.

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