JP2010049273A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which an auxiliary power source device and a fixing device are disposed close to each other and a temperature rise of the auxiliary power source is suppressed. <P>SOLUTION: The auxiliary power source device 7 is disposed in the image forming apparatus 1 and in an empty space between an inverting device 8 below the fixing device and a rear wall that is a part of a side of an external device 12. Alternatively, the auxiliary power source device 7 may be disposed in an empty space defined by detaching a paper feed tray 101 from the image forming apparatus 1. Equally, the auxiliary power source device 7 may be installed on a rear face of an external part of the image forming apparatus 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to a toner fixing device used in an electrophotographic copying machine, a printer, a FAX, and the like.

  Various methods for forming an image on a recording medium such as plain paper or OHP paper by an image forming apparatus such as a copying machine, a printer, or a FAX have been realized. In particular, the electrophotographic method is widely used in image forming apparatuses because of its high speed, high image quality, and low cost.

  In general, in the electrophotographic system, an unfixed toner image is first formed on a recording medium. Next, heat and pressure are applied in the fixing device to fix the toner image on the recording medium. As a method for fixing, a heat roller method is widely used for reasons such as high speed and safety. In this heat roller system, recording is performed by passing a recording medium called a nip portion formed by contacting a heated fixing roller and a pressure roller arranged to face the fixing roller so as to apply pressure. Apply heat and pressure to the medium.

  The fixing roller is heated by a heat generating member such as a halogen heater, and the temperature is raised to about 180 ° C., which is a usable temperature. As the fixing roller, a metal roller made of iron or aluminum is mainly used. Since the metal roller has a large heat capacity, the time for raising the temperature to a usable temperature (hereinafter referred to as the rise time) is as long as several minutes to several tens of minutes. Therefore, in order to shorten the start-up time, the fixing roller is heated even during the time when the image forming apparatus is not used (hereinafter referred to as standby time), and is kept at a preheating temperature slightly lower than the usable temperature.

  However, the operation for maintaining the preheating temperature consumes extra power that is not directly required for image formation during standby. There is also a survey result that the energy consumed during the standby occupies about 70 to 80% of the energy consumed by the image forming apparatus.

  In recent years, regulations on energy conservation have been enacted in various countries around the world due to increasing awareness of environmental protection. Regulations are being strengthened in Japan due to the revision of the Energy Saving Law. In the United States, energy-saving programs such as Energy Star and Zero Energy Star Mode (ZESM) have been established. In order to comply with these regulations and programs, it is desirable that the power supply during standby be close to zero in order to save power in the image forming apparatus.

  However, when the standby power is set to zero in the conventional fixing device, several minutes are required as a rise time after the standby. For this reason, the waiting time is long and user convenience is poor. In order to improve the usability, a configuration for quickly increasing the temperature of the fixing roller is required. For example, the above-mentioned ZESM requires 10 seconds or less as a re-startup time.

  As a method for quickly increasing the temperature of the fixing roller, there is a method for increasing the input energy per unit time. As one method, a method of increasing the rated power has been proposed. However, generally, in domestic offices, the power supply is 100V-15A, so the rated power has an upper limit of 1500W. In fact, some high-speed machines with high printing speeds have a power supply voltage of 200V. However, in order to support 200V, it is necessary to perform special work related to the power supply at the installation site. I can't say that. In addition, a product that raises the total input power by using two 100V-15A power supplies has been put into practical use, but there is a problem that it cannot be installed unless there are two outlets nearby.

  As another method, a method has been proposed in which an auxiliary power supply device is used to increase the maximum power supply during startup. As the auxiliary power supply device, a lead storage battery or a CADNICA battery, which is a rechargeable secondary battery, is typically used. However, the secondary battery has a property that when the battery is repeatedly charged and discharged, the battery deteriorates and the capacity gradually decreases, and the life is shortened as the battery is discharged with a large current. In general, even for a CADNICA battery having a large current and a relatively long life, the limit of the number of charge / discharge cycles is about 500 to 1000 times. Life is coming. For this reason, it takes time and effort to replace the battery, and the running cost of the battery or the like becomes very high. Furthermore, since it takes several hours to charge a large capacity, there is a problem that it cannot be used for applications in which charging and discharging are repeated many times a day. That is, a practical auxiliary power supply cannot be realized with a secondary battery.

  Therefore, Patent Document 1 proposes a method of using a large capacity capacitor such as an electric double layer capacitor as an auxiliary power supply device. Large capacity capacitors have two major advantages. The first advantage is that the limit of the number of charge / discharge cycles is tens of thousands or more. This is almost unlimited, and there is almost no deterioration in charging characteristics, so that periodic maintenance is not necessary. The second advantage is that the charging time is as short as several seconds to several tens of seconds. Note that the electric double layer capacitor can flow a large current of several tens to several hundreds of A, and can supply power in a short time.

  That is, the auxiliary power supply device using a large-capacity capacitor can supply power exceeding the power limit of the commercial power supply in a short time of several seconds to several tens of seconds when the fixing device starts up. For this reason, it is possible to realize a fixing device with a short rise time and high reliability and durability.

  Here, in order to use up the electric power held by the large-capacity capacitor within a rise time of several seconds to several tens of seconds, a configuration for taking out the large electric power is necessary. In order to extract large power, since power = voltage × current, there is a method of increasing either the voltage or the current value.

  The maximum current of a halogen heater usually used for heating the fixing roller is about 10 to 12A. If a large current is supplied, the life of the halogen heater is shortened, so it is difficult to increase the maximum current. Therefore, in order to supply a large amount of power to the halogen heater, it is necessary to use a large voltage power source as a power supply source.

  However, originally, the voltage that can be supplied per cell in a large-capacity capacitor is as low as about 1 V in the water system and several volts in the organic system. This is to prevent electrolysis of the solution inside the cell. For this reason, in order to supply a large voltage to the halogen heater, it is necessary to connect dozens to dozens of cells in series. However, in this configuration, even if the cell already has sufficient energy to be supplied to the halogen heater by some cells, it is necessary to provide an extra cell in terms of energy in order to obtain a high voltage. As a result, there is a problem that the cost of the power source increases and the volume increases.

  In order to solve the problem, Patent Document 2 proposes a method of obtaining a large electric power at a low voltage by connecting a halogen heater in parallel to a large-capacity capacitor. In this method, a large current can be taken out in a short time with a low voltage by utilizing a feature that allows a large current to flow through a large capacity capacitor and setting the resistance of the halogen heater low. As a result, the cost of the capacitor power supply can be reduced and the size of the power supply can be reduced.

  However, if a halogen heater is connected in parallel to a large-capacity capacitor so that a large current flows, a large loss occurs due to Joule heat in the wiring. Since a large current flows in the conductor, if the conductor is thickened to reduce the Joule heat loss and the resistance of the wiring is reduced, a very thick conductor is required and it is very difficult to squeeze in the device, saving space. However, it cannot be planned and the assembly is bad. On the other hand, if the conductor is shortened and the resistance is reduced, the conductor can be made relatively thin, so that the inside of the apparatus can be easily wound, space saving can be achieved, and assemblability can be improved.

  Here, in the electrophotographic image forming apparatus, the internal temperature of the image forming apparatus becomes 70 ° C. to 80 ° C. or more due to heat generated in the fixing device and heat generated due to the recent increase in power consumption of the electric circuit. There are also many. If the wiring is shortened, the large-capacity capacitor and the fixing device are disposed relatively close to each other. Therefore, the environmental temperature of the large-capacity capacitor increases due to heat generated by the fixing device.

  Generally, a large capacity capacitor such as an electric double layer capacitor or a pseudo capacitor called an electrochemical capacitor has a temperature range suitable for use. For example, the use temperature range of a gold capacitor manufactured by Matsushita Electric Industrial Co., Ltd. is about −25 ° C. to + 60 ° C. Moreover, the utilization temperature ranges of the company's lithium ion, nickel metal hydride battery, etc. are about 0 ° C. to + 45 ° C. during charging and about −10 ° C. to + 60 ° C. during discharging. In general, a large-capacity capacitor has a property that durability is lowered when the temperature is excessively high. The main reason for this is thought to be deterioration of the internal electrolyte. Since the decrease in the durability of the electric double layer capacitor due to the temperature rise is due to a secondary chemical reaction, it is considered from the Arrhenius equation that the degradation rate doubles when the environmental temperature rises by 10 ° C. .

  That is, if the wiring distance is shortened to reduce the heat generation and power loss of the wiring due to the large current configuration, the large-capacity capacitor and the fixing device are disposed relatively close to each other. As a result, the large-capacity capacitor is deteriorated, resulting in a problem that the durability of the entire image forming apparatus is deteriorated.

  Further, the fixing device is rapidly heated in about 10 seconds by the auxiliary power supply device using the large capacity capacitor. When image formation is performed immediately after start-up, almost no heat is transferred to the outer layer cover of the fixing device and peripheral components near the fixing, and the temperatures are substantially the same. At this time, the water vapor generated from the paper that has passed through the fixing unit condenses on peripheral parts that are equivalent to room temperature, and the moisture becomes water droplets, and if the moisture enters the circuit part of the auxiliary power source, there is a risk of short circuit or leakage. There is. In addition, when a non-aqueous electric double layer capacitor using an organic solvent as the electrolytic solution is used as a power storage element, intrusion of moisture from a safety valve, a junction, or the like into the capacitor cell leads to significant performance deterioration. Further, since an organic solvent is also used in the secondary battery, the intrusion of moisture into the battery leads to significant performance deterioration.

  An object of the present invention is to provide an image forming apparatus in which an auxiliary power supply device and a fixing device are arranged close to each other, and the temperature rise and condensation of the auxiliary power supply device can be suppressed.

  According to a first image forming apparatus of the present invention, a fixing unit having a plurality of heat generating units for fixing a toner image transferred onto a recording sheet, a main power supply unit for supplying a voltage to a part of the heat generating unit, and a parallel power unit In the image forming apparatus including an auxiliary power supply unit that supplies power charged by the main power supply unit to another part of the heat generating unit connected to the auxiliary power supply unit, the auxiliary power supply unit is disposed below the fixing unit and in the vicinity of the fixing unit. In the second image forming apparatus of the present invention, the auxiliary power supply unit is disposed between one side surface of the housing of the image forming apparatus and the fixing unit, or outside contacting the side surface of the housing of the image forming apparatus. Install.

  A third image forming apparatus of the present invention includes a fixing unit that has a plurality of heat generating units and fixes a toner image transferred to a recording sheet, a main power supply unit that supplies a voltage to a part of the heat generating unit, An auxiliary power supply unit that supplies power charged by the main power supply unit to another part of the heat generating units connected in parallel, and a paper feed unit that detachably accommodates a plurality of paper feed trays that accommodate recording paper In the image forming apparatus including the auxiliary power unit, the auxiliary power unit is installed in a part of the sheet feeding unit.

  Further, a heat insulating member disposed between the fixing unit and the auxiliary power supply unit, a heat insulating member disposed so as to cover the auxiliary power supply unit, or a capacitor of the auxiliary power supply unit including an auxiliary power supply circuit and a capacitor. It is good to provide the heat insulation member which covers. In addition, the image forming apparatus may include a first connection terminal provided in the housing of the image forming apparatus, and a second connection terminal that can be connected to the first connection terminal and is electrically connected to the auxiliary power supply unit. The first connection terminal and the second connection terminal may be detachably formed. Furthermore, the auxiliary power supply unit may include a large-capacity capacitor, and may include a switching unit that switches between electrical connection and disconnection of the connection between the auxiliary power supply unit and the blowing unit that creates a gas flow around the auxiliary power supply unit. Moreover, it is good to use the lead wire of 14 or more thickness by AWG size for the lead wire which connects an auxiliary power supply part and a heat-emitting part. The auxiliary power supply unit may include a capacitor, and may include discharge means for discharging the electric charge stored in the capacitor during maintenance or replacement of the auxiliary power supply unit. The auxiliary power supply unit may include cooling means for cooling the inside of the auxiliary power supply unit.

  In the image forming apparatus of the present invention, the temperature of the capacitor constituting the auxiliary power supply unit can be prevented from excessively rising due to the heat of the fixing unit by disposing the auxiliary power supply unit at a position where the influence of the heat of the fixing unit is small. . Also, by disposing the auxiliary power supply unit near the fixing unit, it is possible to reduce the loss of power generated in the wiring while shortening the wiring and facilitating scooping. Therefore, durability and fixing efficiency can be improved. Further, it is possible to provide a fixing device having a very short rise time without newly providing an auxiliary power supply device and without enlarging the image forming apparatus. Accordingly, durability and fixing efficiency can be improved, and the apparatus can be miniaturized.

  In addition to preventing the capacitor temperature from excessively rising due to the heat generated by the fixing unit due to the use of the shielding member and preventing condensation, the auxiliary power supply unit can be protected from dust generated from the image forming apparatus, Furthermore, the user can be prevented from touching the auxiliary power supply. Furthermore, by making the auxiliary power supply part detachable, it is easy to install, collect and maintain the storage part, and connect the storage part to an image forming apparatus that is not equipped with the auxiliary power supply part in advance. An image forming apparatus having a short rise time using the auxiliary power supply unit can be configured. Further, by providing the discharging means, the electric charge stored in the capacitor can be discharged safely, and the installation, recovery and maintenance of the auxiliary power supply unit can be performed safely. Further, by providing switching means for switching between connection and disconnection of the auxiliary power supply unit and the cooling unit, the charge stored in the capacitor can be discharged safely, and installation, recovery and maintenance of the auxiliary power supply unit can be performed safely. Further, by providing the auxiliary power supply unit with a cooling means, it is possible to prevent the temperature of the capacitor from excessively rising due to heat generated by the fixing unit and to prevent condensation.

1 is a configuration diagram of an image forming apparatus. It is a block diagram of an auxiliary power supply device. It is a figure which shows the arrangement position of the auxiliary power supply device in a screen formation apparatus. It is a block diagram of another auxiliary power supply device. It is a perspective view of an image forming device showing the arrangement position of another auxiliary power unit. It is side surface sectional drawing of the image forming apparatus which shows the arrangement position of another auxiliary power supply device. It is a schematic circuit diagram containing a heating apparatus and an auxiliary power supply device. It is a figure which shows the relationship between the temperature of a heating member, and time. It is a schematic circuit diagram in the case of providing auxiliary heat generation switching means. It is a figure which shows arrangement | positioning of the auxiliary power supply device in a paper feed unit. It is the perspective view and top sectional view of a tray-like auxiliary power unit. It is side surface sectional drawing which shows the other arrangement | positioning of the auxiliary power supply device in a paper feed unit. It is a top sectional view showing other arrangement of an auxiliary power unit in a paper feed unit. It is a figure which shows arrangement | positioning of the auxiliary power supply apparatus in the exterior of a back surface. It is a block diagram of the capacitor arrange | positioned at flat form.

  FIG. 1 shows a configuration diagram of an image forming apparatus 1 according to the first embodiment. The overall height of the image forming apparatus 1 is set so that it can be used on the floor. The image forming apparatus 1 includes a document transport device 2 that transports a document, an optical system 3 that reads an image by irradiating light on the document transported by the document transport device 2, and an image read by the optical system 3 on paper. An image forming device 4 for transferring to a recording member, a fixing device 5 for fixing the transferred image to the recording member, a main power supply device 6 for supplying power to the entire device, and supplying power from the main power supply device 6 An auxiliary power supply device 7 that is charged by receiving and supplying power to the fixing device 5, a reversing device 8 that reverses the front and back of the recording member when the image is transferred and fixed on both sides of the recording member, and the image is fixed A discharge unit 9 that discharges the recording member to the outside, a paper feed unit 10 that stores the recording member and sends it to the image forming device 4, a partition plate 11 that partitions the internal space, and a casing that covers the entire components ( (Exterior part) 12 and paper feed unit 10 or inversion And a conveying path 13 for conveying the recording member fed from location 8 to the image forming apparatus. In the space above the partition plate 11, there are a document conveying device 2, an optical system 3, an image forming device 4, a fixing device 5, a main power supply device 6, an auxiliary power supply device 7, a reversing device 8, and a discharge unit 9. A paper feed unit 10 exists in the space. The partition plate 11 is parallel to the bottom surface of the housing 12 and is formed integrally with the housing 12 with synthetic resin or the like.

  The image forming apparatus 4 includes a photosensitive member 401 that is a drum-shaped rotating body, and a charging roller 402, a mirror 403, a developing device 404, a transfer device 405, and a cleaning device 406 are arranged in this order along the outer periphery of the photosensitive member 401. ing. The charging roller 402 uniformly charges the surface of the photoreceptor 401 in the dark. The mirror 403 scans the charged photoreceptor 401 with exposure light 407 and forms an electrostatic latent image corresponding to the image to be created on the surface of the photoreceptor 401. The developing device 404 uses the developing roller 408 to visualize the electrostatic latent image formed on the photoconductor 401 with toner to form a toner image. The transfer device 405 transfers the toner image to transfer paper as a recording member by an electric field. The cleaning device 406 removes residual toner remaining on the surface of the photoreceptor 401 without being transferred by the transfer device 405. Further, the image forming device 4 includes a registration roller 409. The registration roller 409 adjusts the timing of feeding so that the position of the toner image formed on the surface of the photoconductor 401 and the position of the recording member match in the transfer device 405. The recording member to which the toner image is transferred by the transfer device 405 is sent to the fixing device 5.

  The fixing device 5 receives the recording member to which the toner image has been transferred from the image forming device 4, fixes the toner image on the recording member, and discharges the recording member to the paper discharge unit 9. The fixing device 5 includes a fixing roller 501 that heats the recording member, and a pressure roller 502 that applies pressure to the recording member. The fixing roller 501 has, for example, an aluminum core metal having a thickness of 0.7 mm and a fluororesin layer having a thickness of 0.02 mm as a release layer on the outer side of the core metal. The temperature can be raised in a short time. As shown in FIG. 7, the fixing roller 501 includes one main heat generating member 504 and two auxiliary heat generating members 505. The auxiliary heat generating member 505 is, for example, a halogen heater or a carbon heater.

  A block diagram of the auxiliary power supply device 7 is shown in FIG. The auxiliary power supply device 7 is a device that receives power from the main power supply device 6 and is charged to supply power to the auxiliary heat generating member 505. The auxiliary power supply device 7 includes a capacitor 701 and a charger 702 inside, and has a cubic shield. Covered with a member 703.

  The capacitor 701 is, for example, an electric double layer capacitor, and is stored in the auxiliary power supply device 7 in the form of a capacitor module in which a plurality of capacitor cells are collected. For example, it is stored in the form of a 90V capacitor module in which 36 capacitor cells of 500F and 2.5V are collected. The charger 702 supplies the power of the main power supply device 6 to the capacitor 701 for charging. The shielding member 703 is formed of a heat insulating material such as urethane foam-based foaming resin, for example, and insulates the inside and the outside of the auxiliary power supply device 7 from each other. The shielding member 703 is preferably an insulating member as well as a heat insulating material in order to prevent electric shock.

  The shielding member 703 may use a mold resin from the viewpoint of cost. Further, the mechanical strength of the auxiliary power supply device 7 may be reinforced by installing a metal plate such as aluminum or sheet metal as an exterior of the heat insulating material.

  Further, the connection terminal A704 provided in a part of the shielding member 703 is electrically connected to the electrode terminal 705 connected to the positive electrode and the negative electrode of the capacitor module. The connection terminal B 706 is attached to a part of the housing 12 on the back surface of the image forming apparatus 1 and is electrically connected to the auxiliary heat generating member 504 and the main power supply device 6. The connection terminal A 704 and the connection terminal B 706 have shapes that can be connected to each other so that the auxiliary power supply device 7 can be attached to and detached from the image forming apparatus 1.

  An air intake opening 707 opened in the shielding member 703 allows air to pass between the inside and the outside of the auxiliary power supply device 7. Further, the fan device 708 provided in the shielding member 703 constitutes a blowing means, exhausts air from the inside of the auxiliary power supply device 7 to the outside, and air from the air intake opening 707 to the inside of the auxiliary power supply device 7. Inflow. Or, conversely, air is introduced from the outside of the auxiliary power supply 7 into the inside, and the air is discharged from the air intake opening 707 to the outside of the auxiliary power supply 7. The air flow is adjusted along the capacitor 701. A rotation control unit 709 provided in the auxiliary power supply device 7 controls the rotation of the fan device 708 according to the operation status of the image forming apparatus 1 to prevent the temperature of the capacitor 701 from being excessively cooled.

  Further, the auxiliary power supply device 7 includes a switch 710 that constitutes a switching unit. The switch 710 switches between when the power of the capacitor 701 is supplied to the auxiliary heat generating member 505, when supplied to the fan device 708, and when supplied with power from the main power supply device 6. When the image forming apparatus 1 is normally used, the power of the capacitor 701 is supplied to the auxiliary heat generating member 505. On the other hand, when maintenance or replacement of the capacitor 701 is performed, the electric power stored in the capacitor 701 is discharged by supplying electric power of the capacitor 701 to the fan device 708. For this reason, the switch 710 and the fan device 708 function as discharging means. Further, at the time of charging, the power is stored by supplying the power of the main power supply device 6 to the capacitor 701.

  The arrangement position of the auxiliary power supply device 7 in the screen forming apparatus 1 is shown in FIG. The auxiliary power supply device 7 is disposed inside the image forming apparatus 1 and in a space existing between the reversing device 8 below the fixing device and the rear wall that is a part of the side surface of the housing 12. A part of the shielding member 703 of the auxiliary power supply device 7 may be replaced with a part of the casing of the image forming apparatus 1. For example, the shielding member on the lower surface of the auxiliary power supply device 7 may be replaced with a part of the partition plate 11. The shielding member on the side surface of the auxiliary power supply device 7 may be replaced with a part of the housing 12 on the back surface of the image forming apparatus 1. Note that when the auxiliary power supply device 7 is provided from the beginning of manufacture, such as when a part of the shielding member 703 is replaced with a part of the partition plate 11 or the housing 12, the connection terminal A704 and the connection terminal B706 are provided. It is good also as a structure directly connected electrically without interposing. Further, not all of the auxiliary power supply device 7 is necessarily covered with the heat insulating member 703.

  The air intake opening 707 is preferably positioned on the upstream side of the fixing device 5 with respect to the direction in which the recording paper is conveyed so that cooler air can be taken in. In order to increase the cooling effect, the air intake opening 707 and the fan device 708 are preferably connected to the outside of the image forming apparatus 1.

  Further, by providing the air intake opening 707 at a position other than the position facing the fixing device 5, it is possible to prevent the heat flow from the fixing device from flowing into the auxiliary power supply device 7, and the air containing the moisture of the sheet at the time of fixing. It is possible to reliably prevent dew condensation by touching the shielding member and intrusion of the condensed moisture into the auxiliary power supply device 7.

  For example, according to experiments, when the conventional image forming apparatus 1 operates continuously, the environmental temperature in the vicinity of the fixing device 5 is about 70 ° C. On the other hand, when the image forming apparatus 1 operates continuously, the environmental temperature inside the auxiliary power supply device 7 decreases to about 50 ° C. when the fan device 708 is not used, and about 35 when the fan device 708 is used. Decrease to ~ 40 ° C. Note that a heat radiating plate may be attached to the capacitor 701 in order to further increase the cooling effect. Further, for cooling the inside of the auxiliary power supply device 7, a device method in which a Peltier element or a cooling liquid is circulated by a pump instead of the fan device 708 may be used as a cooling means.

  As shown in FIG. 4, the auxiliary power supply device 7 may be divided into a capacitor module 711 and an auxiliary power supply circuit 712. The capacitor module 711 contains only the capacitor 701 formed of an electric double layer capacitor inside the shielding member 703, and the auxiliary power supply circuit 712 contains the charger 702 and the switch 710. Unlike the secondary battery, the electric double layer capacitor charges and discharges electricity by physical adsorption and detachment, so the internal resistance is low, the capacitor 701 hardly generates heat, and the auxiliary power supply 7 generates heat mainly from the charger. 702 or the like, and only the capacitor 701 is covered by the shielding member 703, so that the heat from the circuit member such as the charger 702 and the fixing device 5 can be obtained without providing the air intake opening 707 and the fan device 708 in the shielding member 703. Can be shielded. By using a heat insulating material having a high heat insulating effect such as a vacuum heat insulating material for the shielding member 703, the temperature rise of the capacitor 701 can be further suppressed.

  When the auxiliary power supply device 7 is divided into the capacitor module 711 and the auxiliary power supply circuit 712, as shown in the schematic perspective sectional view of FIG. 5, the fixing device 5 and the shielding member 713 are inside the image forming apparatus 1. It is good to arrange in a space provided between the shielding member 713 and the back wall 714. By disposing the capacitor module 711 below the auxiliary power supply circuit 712, heat generated in the auxiliary power supply circuit 712 is transmitted upward, so that the temperature rise of the capacitor module 711 can be prevented. By providing the shielding member 713 between the fixing device 5 and the auxiliary power supply device 7, it is possible to prevent condensation due to the heat flow flowing to the capacitor module 711 even when the fixing device 5 is rapidly heated immediately after the power is turned on.

  In the space between the shielding member 713 and the back wall 714, there is provided a main body electrical board 715 on which a controller including a CPU for controlling the main power supply device 6 and the image forming apparatus 1 and a control board are mounted. A fan 716 for cooling the CPU is provided through the back wall 714. As shown in the side sectional view of FIG. 6, by providing an air intake opening 717 in the back wall 714 near the lower side of the auxiliary power supply circuit 712, the air flowing in from the air intake opening 717 is indicated by an arrow as shown by the arrow. The auxiliary power circuit 712 can be cooled by being raised along the line 713 and flowing out of the fan 716. By using the fan 716 for cooling the CPU, there is no need to provide a fan in the auxiliary power supply device 7. Furthermore, the capacitor 701 can be cooled by providing the air intake opening 718 in the shielding member 713 of the capacitor module 711.

  A schematic circuit diagram including the heating member 503, the main power supply device 6, and the auxiliary power supply device 7 is shown in FIG. The main heat generating member 504 is supplied with electric power from the main power supply device 6, and the two auxiliary heat generating members 505 are supplied with electric power from a capacitor 701 provided in the auxiliary power supply device 7. The thickness of the conductive wire connecting the auxiliary power supply device 7 and the auxiliary heat generating member 505 can be appropriately selected in consideration of the assembly property of the auxiliary power supply device 7 and the loss due to Joule heat, and the AWG (American Wire Gauge) size is AWG14. It is preferably thicker than (diameter of about 1.628 mm), and a more preferable range is a thickness of AWG12 (diameter of about 2.053 mm) or more and a thickness of AWG8 (diameter of about 3.264 mm) or less. In addition, it is preferable to use a conductive wire having a size that is large enough to dispose the auxiliary power supply device 7 near the fixing device 5.

  By supplying electric power to the heating member 503 from both the main power supply device 6 and the capacitor 701 simultaneously, a large amount of electric power that can be supplied only by the main power supply device 6 can be supplied to the heating member 503. Therefore, it is possible to shorten the temperature raising time by using the capacitor 701 at the same time, rather than using only the main power supply device 6. FIG. 8 shows the relationship between the temperature of the heating member 503 and time. In addition, although the voltage of the capacitor 701 is a low voltage, by connecting two auxiliary heat generating members 505 in parallel to the capacitor 701, even if the electric power supplied to each auxiliary heat generating member 505 is small, it is supplied to the whole. Electric power is increased.

  For example, when the voltage of the main power supply 6 is about 100V, the voltage of the capacitor 701 is 90V, the resistance of the main heating member 504 is about 8Ω, and the resistance of the halogen heater as the auxiliary heating member 505 is about 9.5Ω, The power of 850 W is extracted from each of the auxiliary heating members 505, and 1200 W can be extracted from the commercial power source connected to the main power supply device 6. Thereby, about 2900 W of electric power exceeding about 1500 W, which is the upper limit of the supply power of the commercial power source, can be used for raising the temperature of the heating member 503. In this example, the rise time when the surface temperature of the fixing roller 501 is raised from 20 ° C. to 180 ° C., which is a temperature required for fixing, is as short as 10 seconds.

  Further, as shown in the circuit diagram of FIG. 9A, power is supplied from the main power supply device 6 to the main heat generating member 504, and power is supplied from the auxiliary power supply device 7 from the capacitor 701 provided on the two auxiliary heat generating members 505. Then, the auxiliary heat generation switching unit 506 may select whether to supply power from the capacitor 701 to one auxiliary heat generation member 505 or to supply power to the two auxiliary heat generation members 505. Since the fixing roller 501 is a thin roller having a small heat capacity, the surface temperature of the fixing roller 501 is prevented from dropping below a necessary fixing temperature required for fixing due to heat being taken away by continuous paper passing immediately after starting. There is a need. Since the amount of power required during continuous paper feeding is relatively smaller than during startup, power is supplied to the two auxiliary heating members 505 during startup, as shown in the circuit diagram of FIG. Electric power is supplied to one auxiliary heat generating member 505 as shown in the circuit diagram of FIG. By switching the number of auxiliary heat generating members 505 that supply power by the auxiliary heat generating switching means 506, the amount of electric power can be adjusted at the time of start-up or continuous sheet passing by a very simple mechanism and control.

  When a halogen heater is used as the auxiliary heat generating member 505, the current supplied to each halogen heater is about 9.5A, resulting in a current configuration of 19A in total. On the other hand, by increasing the number of halogen heaters connected in parallel or by using a carbon heater as the auxiliary heat generating member 505, a configuration with a larger current can be obtained and a larger electric power can be taken out. In addition, the voltage of the electric double layer capacitor used for the capacitor 701 decreases as it is discharged. Therefore, the auxiliary heating member 505 may use a resistance heating element that reliably generates heat even when the supplied voltage decreases.

  When the reversing device 8 forms an image on both sides of the recording member, the reversing device 8 receives the recording member ejected from the fixing device 5 and selected by the branching claw, reverses the surface of the recording member by switchback reversal, and generates a registration roller 409. To the transport path 13 leading to

  The paper feed unit 10 includes a paper feed tray 101 and a paper feed roller 102. The paper feed tray 101 stores recording members of a plurality of sizes for each size. The paper feed roller 102 takes out the recording member stored in the paper feed tray 101 and sends it out to the transport path 13. The conveyance path 13 sends the recording member to the registration roller 409 of the image forming device 4.

  Most of the heat generated by the fixing device 5 is transmitted to the upper side of the fixing device 5 by natural convection, so that it is not transmitted to the inside of the auxiliary power supply device 7. Further, heat transmitted and radiated below the fixing device 5 is shielded by the heat insulating member on the upper surface of the auxiliary power supply device 7, and therefore is not transmitted to the inside of the auxiliary power supply device 7. Further, heat generated from various electronic circuit boards and the like disposed near the back wall of the image forming apparatus 1 (not shown) is also shielded by the shielding member 703 and is not transmitted to the auxiliary power supply device 7. That is, since the capacitor 701 stored in the auxiliary power supply device 7 is isolated from various heat sources, it can be prevented from being deteriorated due to a temperature rise. In addition, the auxiliary power supply device 7 prevents floating matters generated in the image forming apparatus 1 from entering the auxiliary power supply device 7. For example, when the toner is scattered due to an erroneous operation at the time of supplying the toner, the auxiliary power supply device 7 can be prevented from being contaminated by the toner, and the reliability is improved.

  By providing the air intake opening 707 and the fan device 708, it is possible to prevent the temperature of the capacitor 701 from rising due to the heat generated by the electric circuit constituting the auxiliary power supply device 7 stored inside the auxiliary power supply device 7. . Further, when a heat sink is provided in the capacitor 701, the cooling effect is further increased. The rotation control device 706 can prevent the capacitor 701 from being excessively cooled by the fan device 708 and can reduce power consumption by the fan device 708 when cooling is unnecessary.

  As shown in the side sectional view of FIG. 10, the auxiliary power supply device 720 may be disposed in a space formed by removing the paper feed tray 101 from the image forming apparatus 1. As shown in the perspective view of FIG. 11 (a), the exterior of the auxiliary power supply device 720 is formed in a tray shape by a shielding member 723 made of molded resin, and covers the accommodation space 721 provided inside. The storage convex portion 722 formed integrally with the side surface of the paper supply unit 723 is replaced with the paper supply tray 101 and stored along the paper supply tray guide rail 724 of the paper supply unit 10. 11B, the storage space 721 of the shielding member 723 accommodates the capacitor 701, the charger 702, and the switch 710, and the connection terminal A704 protrudes from the back side of the shielding member 723. ing. When the auxiliary power supply 720 is accommodated in the paper supply unit 10, the connection terminal A 704 is connected to the connection terminal B 706 provided in the main body electrical unit 725 on the back side of the paper supply unit 10, whereby the auxiliary power supply 720 and The fixing device 5 is electrically connected. The auxiliary power supply device 720 is fastened to the base portion 12 with screws or other means so that the user does not touch the inside of the auxiliary power supply device 720. Note that the mechanical strength of the exterior may be strengthened by a metal member such as aluminum or sheet metal, and only the capacitor 701 may be covered with the shielding member 723, and the air intake opening 707 and the fan device 708 are provided in the shielding member 723. May be.

  By disposing the space below the fixing device 5 and below the partition plate 11, the influence of heat generated from the fixing device 5 can be suppressed, and assisting when the fixing device is rapidly heated immediately after the power is turned on. It is possible to prevent dew condensation on the power supply device 720. Further, it is not necessary to newly provide a space including the capacitor 701, and the image forming apparatus 1 can be downsized. Furthermore, an auxiliary power supply device 720 can be additionally installed in an image forming apparatus that does not have the auxiliary power supply device 720 mounted in advance, with the same housing components.

  Further, as shown in the side sectional view of FIG. 12, the space between the paper feed tray 101 and the back wall 714, which is the lower part of the partition plate 11 of the paper supply unit 10, is covered with the partition plate 726, and the auxiliary power supply device 7 may be arranged inside. When a large image forming apparatus having a space for storing A3 size plain paper contains, for example, frequently used plain paper of A4 size or less, the paper supply unit 10 has a sufficient space, so it is empty. By disposing the auxiliary power supply device 7 in the space, the space can be effectively used to reduce the size of the device, and the dew condensation due to the rapid heating of the fixing device 5 immediately after the power is turned on while suppressing the influence of heat generated from the fixing device 5. Can be prevented. As shown in the cross-sectional plan view of FIG. 13, a paper feed tray guide rail is provided on the partition plate 726 so that the paper feed tray 101 can be accommodated adjacently. The auxiliary power supply device 7 is preferably separated into a capacitor module 711 and an auxiliary power supply circuit 712, and the capacitor module 711 is preferably cut off from the heat of the auxiliary power supply circuit 712.

  Further, as shown in FIG. 14, an auxiliary power supply device 7 may be installed on the back surface outside the image forming apparatus 1. As illustrated in FIG. 15, the capacitor 701 is laminated in a flat plate shape, thereby suppressing an increase in the depth of the image forming apparatus 1. For example, the size of this flat plate can be about 30 cm long × 30 cm wide × 5 cm deep. By disposing the auxiliary power supply device 7 outside the image forming apparatus 1, the capacitor is not affected by the temperature inside the image forming apparatus 1 and the heat generated from the fixing device 5. It is possible to prevent condensation due to rapid heating of the fixing device immediately after the power is turned on.

  The present invention can be applied to an electrophotographic image forming apparatus, and can also be applied to other apparatuses related to a heating apparatus using electricity as a main energy source.

DESCRIPTION OF SYMBOLS 1; Image forming apparatus, 2; Document conveying apparatus, 3; Optical system, 4: Image forming apparatus, 5: Fixing apparatus,
6; main power supply, 7; auxiliary power supply, 8; reversing device, 9; discharge part,
10; Paper feeding unit, 11; Partition plate, 12; Housing (exterior part), 13;
101; paper feed tray, 102; paper feed roller, 401; photoconductor, 402; charging roller,
403; mirror, 404; developing device, 405; transfer device,
406; cleaning device, 407; exposure light, 408; developing roller,
409; registration roller; 501; fixing roller; 502; pressure roller;
503; heating member, 504; main heating member, 505; auxiliary heating member,
506; auxiliary heat generation switching means, 701; capacitor, 702; charger,
703; shielding member, 704; connection terminal A, 705; electrode terminal, 706; connection terminal B,
707; air intake opening, 708; fan device, 709; rotation control means,
710; switch, 711; capacitor module, 712; auxiliary power circuit,
713; shielding member, 714; back wall, 715; main body electrical board, 716; fan,
717; air intake opening, 718; air intake opening, 720; auxiliary power supply,
721; accommodation space, 722; accommodation convex part, 723; shielding member,
724; guide rail for paper feed tray, 725; main body electrical component, 726; partition plate.

JP 2000-315567 A JP 2000-184554 A

Claims (12)

A fixing unit having a plurality of heat generating units and fixing the toner image transferred to the recording paper;
A main power supply for supplying a voltage to a part of the heat generating part;
In an image forming apparatus comprising: an auxiliary power supply that supplies power charged by the main power supply to another part of the heat generating parts connected in parallel;
The image forming apparatus, wherein the auxiliary power supply unit is disposed below the fixing unit and in the vicinity of the fixing unit. A fixing unit having a plurality of heat generating units and fixing the toner image transferred to the recording paper;
A main power supply for supplying a voltage to a part of the heat generating part;
In an image forming apparatus comprising: an auxiliary power supply that supplies power charged by the main power supply to another part of the heat generating parts connected in parallel;
The auxiliary power supply unit is an image forming apparatus that is installed between one side surface of the housing of the image forming apparatus and the fixing unit or outside the side surface of the housing of the image forming apparatus. A fixing unit having a plurality of heat generating units and fixing the toner image transferred to the recording paper;
A main power supply for supplying a voltage to a part of the heat generating part;
An auxiliary power supply unit that supplies power charged by the main power supply unit to another part of the heat generating units connected in parallel;
In an image forming apparatus comprising a paper feed unit that detachably accommodates a plurality of paper feed trays that accommodate the recording paper,
The auxiliary power unit is an image forming apparatus installed in a part of the paper feeding unit.   The image forming apparatus according to claim 1, further comprising a heat insulating member disposed between the fixing unit and the auxiliary power source unit.   The image forming apparatus according to claim 1, further comprising a heat insulating member arranged to cover the auxiliary power supply unit.   The image forming apparatus according to claim 1, wherein the auxiliary power supply unit includes an auxiliary power supply circuit and a capacitor, and the capacitor is covered with the heat insulating member. A first connection terminal provided in a housing of the image forming apparatus;
4. The image forming apparatus according to claim 1, further comprising a second connection terminal that is connectable to the first connection terminal and is electrically connected to the auxiliary power supply unit. 5.   The image forming apparatus according to claim 7, wherein the first connection terminal and the second connection terminal are detachably formed.   4. The image formation according to claim 1, wherein the auxiliary power supply unit includes a capacitor, and includes discharge means that discharges electric charge stored in the capacitor during maintenance or replacement of the auxiliary power supply unit. 5. apparatus. The auxiliary power supply unit includes a large-capacity capacitor,
The image formation according to any one of claims 1 to 3, further comprising a switching unit that switches between electrical connection and disconnection of the connection between the auxiliary power supply unit and a blowing unit that creates a gas flow around the auxiliary power supply unit. apparatus.   The image forming apparatus according to claim 1, wherein an AWG size conductor having a thickness of 14 or more is used as a conductor connecting the auxiliary power supply unit and the heat generating unit.   The image forming apparatus according to claim 1, wherein the auxiliary power supply unit includes a cooling unit that cools the inside of the auxiliary power supply unit.

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