JP4326975B2 - Image forming apparatus - Google Patents

Description

The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile.

  Image forming apparatuses such as copiers, printers, and facsimiles need to reduce energy consumption during standby after image formation in order to save power. For this reason, it is necessary to keep the standby temperature of the fixing roller in the fixing device of the image forming apparatus at a low value, and the waiting time for returning the temperature of the fixing roller from the standby temperature to a temperature at which fixing is possible. In order to reduce this, it is necessary to reduce the heat capacity of the fixing roller.

  However, a fixing roller having a reduced heat capacity is compared with a fixing roller having a large heat capacity when the toner on the transfer material is deprived of heat when the toner on the transfer material is fixed to the transfer material during image formation. There is a problem that the fixing roller surface temperature drops quickly and falls below a lower limit temperature that satisfies the fixing property, and fixing defects are likely to occur.

  Therefore, in order to solve the above problems, not only power is supplied from the main power supply device to the fixing heater for heating the fixing roller, but also an auxiliary power supply device that can be charged is provided in the image forming apparatus, and the auxiliary power supply device is used at the time of image formation. A fixing device has been proposed that prevents a decrease in the surface temperature of the fixing roller by supplying power to the fixing heater. In this fixing device, the auxiliary power supply device is allowed to start discharging only when it is fully charged (charged to a predetermined discharge start permission value or more).

  Patent Document 1 uses a chargeable / dischargeable capacitor for the auxiliary power supply, the charger charges the capacitor of the auxiliary power supply with power supplied from the main power supply, and the switching device charges the auxiliary power supply. And an apparatus for switching the power supply from the auxiliary power supply to the auxiliary heating element and adjusting the amount of power supplied from the auxiliary power supply to the auxiliary heating element.

JP 2002-184554 A

  In the fixing device that permits the discharge start of the auxiliary power supply only when the auxiliary power supply is fully charged, after the discharge of the auxiliary power supply and image formation is completed, the auxiliary power supply is less than the discharge start permission value. Charging time is required when charging from an uncharged charging state until the auxiliary power supply is full, and there is a possibility that a waiting time due to charging of the auxiliary power supply occurs before image formation.

  Therefore, by permitting the auxiliary power supply device to start discharging even when the auxiliary power supply device is in the middle of charging, it is possible to eliminate the waiting time due to the charging of the auxiliary power supply device before image formation. However, in this way, when the auxiliary power supply device starts discharging in the middle of charging, the auxiliary power supply device discharges from a lower power value than in the case of starting discharging in the storage capacity upper limit charging state, When the input voltage value of the main power supply is low or the environmental temperature is relatively low, the surface temperature of the fixing roller drops quickly and falls below the lower limit temperature that satisfies the fixability, and fixing defects are likely to occur. .

An object of the present invention is able to achieve an appropriate discharge of the auxiliary power supply becomes possible to eliminate the waiting time due to charging of the auxiliary power unit in the image forming earlier, an image forming apparatus capable of preventing fixing failure Is to provide.

In order to achieve the above object, an invention according to claim 1 is an image forming apparatus having a main power supply device, an auxiliary power supply device, and a fixing device , wherein the auxiliary power supply device has a chargeable / dischargeable power storage device, and the fixing device device has a heating unit to which electric power is supplied from the auxiliary power unit and the main power supply, at the time of continuous paper feed through the recording medium in the launch or during the fixing device of the fixing device, the voltage of the electric storage device Alternatively, when the electric power or the amount of stored electricity is equal to or greater than a first discharge start permission value, the discharge of the power storage device is permitted, and when the fixing device is started up or during continuous paper passing through the fixing device, When the input voltage value of the main power supply device is higher than a predetermined value when the voltage or power of the power storage device or the storage amount is equal to or higher than a second discharge start permission value that is less than the first discharge start permission value. said power storage device is charged way shape Also the in is also you allow discharge of said power storage device comprising a.

According to a second aspect of the present invention, in the image forming apparatus including a main power supply device, an auxiliary power supply device, and a fixing device, the auxiliary power supply device includes a chargeable / dischargeable power storage device, and the fixing device includes the main power supply device. A heating unit to which electric power is supplied from the apparatus and the auxiliary power supply device, and when the fixing device is started up or when a recording medium is continuously passed through the fixing device, the voltage, power, or amount of electricity stored in the power storage device is When the discharge start permission value is greater than or equal to the first discharge start value, the discharge of the power storage device is permitted, and the voltage or power of the power storage device is turned on when the fixing device is started up or when a recording medium is passed through the fixing device. Alternatively, when the storage amount is equal to or higher than the second discharge start permission value that is less than the first discharge start permission value, and the temperature of the pressure member of the fixing device is higher than a predetermined value, the power storage device Even during charging It is intended to allow the discharge of the location.

According to a third aspect of the present invention, in the image forming apparatus including a main power supply device, an auxiliary power supply device, and a fixing device, the auxiliary power supply device includes a chargeable / dischargeable power storage device, and the fixing device includes the main power supply device. A heating unit to which electric power is supplied from the apparatus and the auxiliary power supply device, and when the fixing device is started up or when a recording medium is continuously passed through the fixing device, the voltage, power, or amount of electricity stored in the power storage device is When the discharge start permission value is greater than or equal to the first discharge start value, the discharge of the power storage device is permitted, and the voltage or power of the power storage device is turned on when the fixing device is started up or when a recording medium is passed through the fixing device. Alternatively, when the storage amount is equal to or higher than a second discharge start permission value that is less than the first discharge start permission value, and the environmental temperature of the fixing device is higher than a predetermined value, the power storage device is in the middle of charging. Even of the power storage device It is intended to allow the electricity.

According to a fourth aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein the voltage, power or charged amount of the power storage device is lower than the second discharge start permission value and equal to or higher than a minimum dischargeable voltage, and When the input voltage value of the main power supply device is higher than a predetermined value, discharge of the power storage device is permitted even when the power storage device is being charged .

According to a fifth aspect of the present invention, there is provided the image forming apparatus according to the second aspect, wherein the voltage, power, or charged amount of the power storage device is lower than the second discharge start permission value and equal to or higher than a minimum dischargeable voltage, and When the temperature of the pressurizing member is higher than a predetermined value, discharging of the power storage device is permitted even when the power storage device is being charged .

According to a sixth aspect of the present invention, there is provided the image forming apparatus according to the third aspect, wherein the voltage, power or charged amount of the power storage device is lower than the second discharge start permission value and equal to or higher than a minimum dischargeable voltage, and When the environmental temperature is higher than a predetermined value, discharge of the power storage device is permitted even when the power storage device is being charged .

According to a seventh aspect of the invention, in the image forming apparatus according to any one of the first to sixth aspects, the power storage device is a capacitor .

According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the power storage device is a battery .

According to the present invention, it is possible to optimize the discharge of the auxiliary power supply device.
According to the present invention, it is possible to eliminate the waiting time due to the charging of the auxiliary power supply device before the image formation, and it is possible to prevent fixing failure.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 shows Embodiment 1 of the present invention. The first embodiment is a copying machine as an image forming apparatus. The copying machine according to the first embodiment includes an image reading device 11 that reads an image of a document, an image forming unit 12 that forms an image on a recording medium such as recording paper, an automatic document feeder (ADF) 13, and a document that is discharged by an ADF 13. A sheet discharge tray 14 for stacking sheets, a sheet feed section 19 including sheet cassettes 15 to 18, and a sheet discharge section (sheet discharge tray) 20 for stacking recording sheets.

  When a document D is set on the document table 21 of the ADF 13 and an operation unit (not shown), for example, a print key is pressed, the uppermost document D on the document table 21 is rotated in the direction of arrow B 1 by the rotation of the pickup roller 22. And is fed onto the contact glass 24 fixed to the image reading device 11 by the rotation of the document conveying belt 23 and set at a predetermined position on the contact glass 24.

  The image of the document D set on the contact glass 24 is read by the image reading device 11. The image reading device 11 illuminates the document D on the contact glass 24 with the light source 26 and forms an image of the reflected light on the photoelectric conversion element 28 such as a CCD by the optical system 27. The document D is scanned by a part of the movement to read the image of the document D. The document D is transported in the direction of arrow B2 by the rotation of the transport belt 23 after the image reading is completed, and is discharged onto the paper discharge tray 14. As described above, the documents D on the document table 21 are fed one by one onto the contact glass 24 and the image is read by the image reading device 11.

  On the other hand, a drum-shaped photoconductor 30 as an image carrier is disposed inside the image forming unit 12. The photoconductor 30 is rotationally driven in a clockwise direction in FIG. 1 by a drive unit (not shown), and the surface is charged to a predetermined potential by the charging device 31. Further, the writing unit 32 as an exposure unit inputs the read image information from the image reading device 25 after various image processing is performed by the image processing unit, drives the laser light source according to the image information, and reads the read image. A laser beam L modulated with information is emitted, and the charged surface of the photoconductor 30 is exposed with the laser beam L, whereby an electrostatic latent image is formed on the surface of the photoconductor 30. The electrostatic latent image is developed by the developing device 33 to form a toner image. The toner image is transferred by the transfer device 34 to the recording medium P fed between the photosensitive member 30 and the transfer device 34. The The surface of the photoreceptor 30 after the toner image transfer is cleaned by a cleaning device 35.

  A plurality of paper feed cassettes 15 to 18 arranged below the image forming unit 12 contain recording media P such as paper, and the recording media P is fed from any of the paper feed cassettes 15 to 18 in the direction of arrow B3. When the recording medium P passes between the photoreceptor 30 and the transfer device 34, the toner image on the photoreceptor 30 is transferred as described above. When the recording medium P passes through the fixing device 36 in the image forming section 12 as indicated by an arrow B4, the toner image is fixed by the action of heat and pressure. The recording medium P that has passed through the fixing device 36 is discharged and stacked on the discharge tray 20 by the discharge roller pair 37 as indicated by an arrow B5.

FIG. 2 shows an example of the fixing device 36 that fixes the toner image on the recording medium P to the recording medium P by heating and pressing, and FIG. 3 shows the configuration of the heating device in the fixing device 36.
The fixing device 36 includes a fixing roller 40 and a pressure roller 41 that is pressed against the fixing roller 40 by a pressure unit (not shown). For example, in the case of a copying machine with a linear speed of 75 cpm, the fixing device 40 is an external fixing roller 40. An aluminum roller having a diameter of φ40 and a wall thickness t of 0.7 mm is used. This is because the thickness of the fixing roller 40 can raise the temperature of the fixing roller 40 so that it can be fixed within 30 seconds, and it is not broken even by a load necessary to form the nip width N necessary for fixing. . In the case of a copying machine with a linear speed of 75 cpm, when a supplementary power source is not used, a thick roller having a t of about 5.0 to 10 mm has been used as a fixing roller. However, a thin roller and an auxiliary power source are combined. As a result, the start-up time of the fixing roller can be greatly reduced.

  It is desirable that a release layer such as PFA or PTFE is formed on the outermost layer of the fixing roller 40. The fixing roller 40 has a built-in heating unit 2 having a main heating element 2a and an auxiliary heating element 2b made of, for example, a halogen heater. The fixing roller 40 and the pressure roller 41 allow the recording medium P on which the toner T is placed to pass therethrough. Thus, a nip portion N for pressurizing and heating is formed.

  The heating device 1 of Embodiment 1 includes a heating unit 2, a main power supply device 3, an auxiliary power supply device 4, a switch 5, a charger 6, a switching device 7, and a control unit 8. In FIG. 3, the heating unit 2 composed of the main heating element 2a and the auxiliary heating element 2b is drawn outside the fixing roller 40. However, this is for the convenience of illustration, and both the heating elements 2a, 2b are drawn. Is provided in the fixing roller 40.

  The heating unit 2 includes a main heating element 2a that generates heat by the electric power supplied from the main power supply device 3, and an auxiliary heating element 2b that generates heat by the electric power supplied from the auxiliary power supply device 4, and is a fixing roller that is a heated object. 40 is heated. Although not shown in detail, the main power supply device 3 is supplied with power from a commercial power supply in the image forming apparatus in which the heating device 1 is installed. The main power supply device 3 has a function of adjusting, for example, power supplied from an outlet or the like to a voltage corresponding to the heating unit 2.

  The auxiliary power supply 4 has a chargeable / dischargeable capacitor C. As the capacitor C, for example, a module configuration in which a predetermined rated voltage and capacity are obtained by connecting 15 to 40 cells having a rated voltage of 2.5 V and a capacitance of about 400 to 1000 F in series is desirable. Furthermore, for use in preventing a decrease in fixing temperature during continuous paper passing, for example, a heating element having a rating of about 300 to 600 w is connected to 18 to 22 cells of 500 to 700 F in series, which is suitable for the capacitor C. . This capacitor C has sufficient capacity for power supply for about 1 to 2 minutes, and when all the stored power is supplied from a high temperature state due to a runaway control system, the power decreases as the voltage decreases, and there is a risk of ignition. This is because the capacity can be reduced. Another reason is that the voltage is about 50V and there is no danger of electric shock.

  In addition, the capacitor C is used for supplying power to the heating unit 2 when the heating device 1 is started up. For example, a heating element 2b with a rating of 800 to 1000 w is connected in parallel to the auxiliary power supply device 4 to obtain a total of 1600 to 2000 w. In order to supply a certain amount of power to the heating element 2b, it is suitable to connect 36 to 44 cells of 500 to 700F in series. This is provided with a capacity and voltage for supplying sufficient power for power supply of about 10 seconds, and can prevent a decrease in fixing temperature by using only one of the heating elements 2b even when transitioning during continuous paper feeding. This is because it has a capacity. In the actual operation state, the capacitor C uses a voltage lower than the rated voltage as the charge target voltage because it is possible to improve the reliability in consideration of variations in the voltage circuit and the durability of the capacitor cell. The capacitor C may have a module configuration in which a plurality of cells having lower capacitances of about 100 F are connected in parallel. However, when a cell malfunctions, the number of electronic circuits required per cell can be reduced. It is desirable to connect all the cells in series for easy detection. The capacitor C has the above configuration because a capacitor such as an electric double layer capacitor has excellent characteristics because it does not involve a chemical reaction unlike a secondary battery.

  In the auxiliary power supply using a general nickel-cadmium battery as a secondary battery, a long time of several tens of minutes to several hours is required even if rapid charging is performed, but in the auxiliary power supply 4 using the capacitor C, several minutes are required. When the standby state and the heating state are repeated within the same time, by using the auxiliary power supply device 4 using the capacitor C, the auxiliary power supply device 4 can be reliably turned on at the start of heating. Electric power can be supplied to the heating element 2b, and the heating unit 2 can be raised to a predetermined temperature in a short time.

  Further, since the nickel-cadmium battery has an allowable number of charge / discharge repetitions of about 500 to 1000 times, it has a short life as an auxiliary power supply for heating, and there is a problem in replacement labor and cost. The auxiliary power supply device 4 using the multilayer capacitor as the capacitor C has an allowable number of repetitions of charge / discharge of several million times or more, and has little deterioration due to repetition of charge / discharge. Therefore, it can be used stably for a long time with little maintenance.

  In addition, the electric double layer capacitor has no dielectric and uses the adsorption / desorption reaction (charging / discharging) of the ion adsorbing layer of the electric double layer in which charges of ions or solvent molecules concentrated at the solid electrode and solution interface are concentrated. It is strong against repeated charging / discharging, has a long life, does not require maintenance, is environmentally friendly, has a shorter charging time than other types of batteries, has higher charging / discharging efficiency, and has a remaining power due to voltage detection. Recently, a large-capacity product having excellent features such as easy-to-understand and having a capacitance of several tens of thousands F and an energy density of several tens of wh / kg has been developed, and the capacity has been further increased.

  The switch 5 turns on / off the power supplied from the main power supply 3 to the main heating element 2a, and the charger 6 charges the capacitor C of the auxiliary power supply 4 with the power supplied from the main power supply 3. To do. The switching device 7 switches between charging the auxiliary power supply 4 and supplying power from the auxiliary power supply 4 to the auxiliary heating element 2b.

  The control means 8 includes a switch 9 and a CPU 10 and performs control to turn on / off the power supplied from the auxiliary power supply 4 to the auxiliary heating element 2b, as will be described later. However, the configuration of the control unit 8 may be various configurations such as being shared not only by a portion that controls the heating unit 2 but also by a control device that controls the entire image forming apparatus. Further, the connection form for controlling the auxiliary power supply 4 by the control means 8 is not limited to the illustrated example. For example, the control means 8 can adopt various forms such as a configuration in which the switching device 7 is switched to perform control such as on / off. The control unit 8 controls the switch 5 to be turned on / off based on a detection signal from a temperature detector that detects the surface temperature of the fixing roller 40 so that the surface temperature of the fixing roller 40 is maintained at a predetermined temperature. Shall be performed.

  The basic operation of such a heating device 1 will be described. First, when the first embodiment does not perform image formation, the switching device 7 connects the auxiliary power supply 4 to the charger 6, and the charger 6 uses the power from the main power supply 3 to connect the capacitor C of the auxiliary power supply 4. Is charged so that the voltage (or power) of the auxiliary power supply 4 is equal to or higher than the first discharge start permission value. The switch 5 is turned on / off so that the surface temperature of the fixing roller 40 is maintained at a standby temperature (a predetermined temperature lower than the fixing temperature).

  When the heating unit 2 is heated in this state, the switch 5 is turned on and power is supplied from the main power supply device 3 to the main heating element 2a via the switch 5, and at the same time the voltage (or power) of the auxiliary power supply device 4 is supplied. Is greater than or equal to the first discharge start permission value, the switching device 7 connects the auxiliary power supply 4 to the auxiliary heating element 2b, and power is supplied from the auxiliary power supply 4 to the auxiliary heating element 2b, whereby the heating unit 2 is supplied with a large amount of power. Thus, when the heating of the fixing roller 40 by the heating unit 2 is started, a large amount of power is supplied from both the main power supply device 3 and the auxiliary power supply device 4 to the heating unit 2. The temperature can be raised to a predetermined temperature in a short time.

  Further, the control unit 8 supplies power from the auxiliary power supply 4 to the auxiliary heating element 2b of the heating unit 2 and starts heating the fixing roller 40. After a predetermined time has elapsed, the surface temperature of the fixing roller 40 is increased. When the predetermined fixing temperature is reached, the electric power supplied from the auxiliary power supply 4 to the auxiliary heating element 2b is cut off by turning off the switch 9 to prevent the heating unit 2 from being overheated to the predetermined temperature. maintain. The electric power supplied from the auxiliary power supply 4 to the auxiliary heating element 2b decreases as time elapses after the supply is started. A time for cutting off the power supplied from the auxiliary power supply 4 to the auxiliary heating element 2b is determined according to the reduction amount of the supplied power, and when the supply power is reduced to some extent, the auxiliary power supply 4 changes to the auxiliary heating element 2b. When the supplied power is cut off, the deterioration of each component of the surrounding circuit and electromagnetic noise that occur when the supply power of the auxiliary power supply 4 is cut off while a large amount of power is being supplied from the auxiliary power supply 4 is prevented. be able to.

  The recording medium P to which the toner image T sent to the fixing device 36 having such a configuration is transferred is conveyed between the fixing roller 40 and the pressure roller 41 and is heated by the fixing roller 40 to a certain temperature. The toner T is heated and melted and fixed. Therefore, power is supplied from the main power supply device 3 and the auxiliary power supply device 4 to the main heating element 2a and the auxiliary heating element 2b of the heating unit 2 in the fixing roller 40, thereby increasing the temperature of the fixing roller 40, and The power supplied from the auxiliary power supply 4 is controlled to be turned on / off by the switch 9, so that the temperature of the fixing roller 40 is prevented from becoming too high, and the fixing temperature (surface temperature of the fixing roller 40) is constant. The toner T is maintained at a temperature or a desired temperature, or controlled so as to exhibit a required temperature change, and the toner T is stably heated and melted to fix a good quality toner image T on the recording medium P. In addition, since the power is supplied from the main power supply device 3 and the auxiliary power supply device 4 to the main heating element 2a and the auxiliary heating element 2b of the heating unit 2 built in the fixing roller 40, the temperature of the fixing roller 40 rises. The surface temperature of 40 rapidly rises to a predetermined fixing temperature.

  4A shows changes in power consumption of the image forming apparatus configured as described above, and FIGS. 4B and 4C show changes in voltage of the capacitor C. FIG. The power consumption of the image forming apparatus increases from the low power consumption state to the upper limit value when the image formation is started from the state that does not consume much power during the standby time, decreases slightly from the upper limit value during image formation, and then returns to the standby state. . In general, the image forming apparatus charges the capacitor C of the auxiliary power supply device 4 by utilizing the power margin (indicated by X in FIG. 4) during image formation. The output voltage of the capacitor C shows the maximum value during standby, decreases when power is supplied to the heating unit 2 for heating the fixing roller 40 during startup, and goes into standby mode when charged during image formation. And return.

  In FIG. 4B, the solid line indicates the output voltage of the capacitor C when the auxiliary power supply 4 is charged during image formation, and the alternate long and short dash line indicates the output of the capacitor C when the auxiliary power supply 4 is charged immediately after image formation. Indicates voltage. In general, the auxiliary power supply 4 is charged immediately after image formation. This is because, when image formation is performed immediately after image formation is completed, if the capacitor C is not fully charged, the cpm (copy speed) decreases. This is because a charging waiting time occurs and the function of the entire image forming apparatus is deteriorated. That is, when the power supplied from the auxiliary power supply 4 to the auxiliary heating element 2b is cut off, the auxiliary power supply 4 is not sufficiently charged. Therefore, when the temperature of the fixing roller 40 is stable and the heating unit 2 does not consume relatively power, the switching device 7 switches the auxiliary power supply device 4 to the charger 6 side, and the charger 6 connects the main power supply device 3. The auxiliary power supply 4 is charged with the power supplied from. When it is necessary to supply a large amount of power again to the heating unit 2, the switching device 7 connects the auxiliary power supply 4 to the auxiliary heating element 2 b and supplies power from the auxiliary power supply 4 to the heating unit 2 together with the main power supply 3. By doing so, a large amount of energy is supplied to the heating unit 2.

  Further, FIG. 4C shows that the surface temperature of the fixing roller 40 is lowered due to insufficient power supply to the heating unit 2 during continuous sheet passing of the recording medium P through the fixing device 36. The output voltage of the capacitor C at the time of using the capacitor C for the prevention use is shown. In general, since the entire apparatus is cooled immediately after the start-up, the power supplied to the heating unit 2 is likely to be insufficient. Therefore, the switching device 7 connects the auxiliary power supply 4 to the auxiliary heating element 2b during continuous paper feeding. Then, power is supplied from the capacitor C to the heating unit 2. Thereby, it becomes possible to prevent a decrease in productivity such as cpm down or stop until the surface temperature of the fixing roller 40 recovers during continuous paper feeding.

  FIG. 5 shows the temperature change of the fixing roller 40. The surface temperature of the fixing roller 40 is low during standby, and rises to a predetermined fixing temperature (180 ° C. in FIG. 5) due to the heat generated by the two heating elements 2a and 2b as described above. The fixing temperature is maintained, and the process gradually decreases as the image forming operation ends. At this time, the temperature of the fixing roller 40 decreases to room temperature (the temperature at the place where the image forming apparatus is installed) or the temperature inside the image forming apparatus depending on environmental conditions.

  By the way, when the capacitor C is discharged to the discharge stop voltage, it is naturally necessary to charge the capacitor C to prepare for the next discharge. In addition, if the device is not used for a long time, the voltage of the capacitor C decreases due to natural discharge, and it takes time to start up the device. Therefore, the voltage of the capacitor C is automatically detected and the capacitor C is automatically charged. In some cases, in order to make the capacitor C dischargeable, it is necessary to charge the capacitor C to a predetermined minimum voltage. Although the time required for charging the capacitor C is a short time of several tens of seconds to 2 minutes, the capacitor C cannot be used during that time.

  Therefore, in the first embodiment, in order to shorten the charging time of the capacitor C, the CPU 10 controls the auxiliary power supply by controlling the switch 9 when the voltage (or power) of the auxiliary power supply device 4 is equal to or higher than the first discharge start permission value. In addition to permitting the discharge of the device 4, the CPU 10 controls the switch 9 based on the predetermined judgment information when the voltage (or power) of the auxiliary power supply 4 is less than the first discharge start permission value, and the auxiliary power supply Allow 4 discharges. The determination information is information related to the status of the heating device 1, in other words, information such as the temperature of the heating device 1 itself, the fixing device 36 using the same, and the image forming apparatus.

  FIG. 6 shows that the capacitor C used for heating the fixing roller 40 in the above-described image forming apparatus starts charging from the discharge stop state, fully charged (charging capacity upper limit charge that is stopped by charging until the charging capacity upper limit value), and discharging. It shows the voltage change that leads to the voltage drop due to. For example, when the voltage of the auxiliary power supply 4 is equal to or higher than the first discharge start permission value, which is a predetermined voltage slightly lower than 50 V, the CPU 10 switches the capacitor C at the switch 9. To allow the auxiliary power supply 4 to discharge. Further, even if the voltage (or power) of the capacitor C is less than the first discharge start permission value during the charging of the capacitor C, the CPU 10 determines if the voltage of the capacitor C is 30 V or more which is the lowest voltage that can be discharged. The switch 9 is controlled according to the information to permit the auxiliary power supply 4 to discharge. Of course, the above voltage value is merely an example, and the voltage of the capacitor C may be 45 V when fully charged, the minimum dischargeable voltage is 32 V, the discharge stop voltage is 2 V, and the present invention is limited to this example. Not. Further, for example, less than 1 minute from the charging start time t1 of the capacitor C to the lowest dischargeable voltage reaching time t2, and within 2 minutes (1 to 1.5 minutes) from the fully charging (charging stop) voltage reaching time t3. Yes, this is just an example.

  In the first embodiment, the determination information is information on the input voltage value of the main power supply device 3, and various known means may be adopted as input voltage detection means for detecting the input voltage value of the main power supply device 3. . The control means 8 controls the switch 9 based on the input voltage detection value of the main power supply device 3 detected by the input voltage detection means, and permits the auxiliary power supply device 4 to discharge. For example, the control unit 8 determines that the voltage (or power) of the capacitor C is less than the first discharge start permission value and the minimum dischargeable voltage based on the voltage detection value of the auxiliary voltage detection unit that detects the voltage of the auxiliary power supply device 4. When higher than the higher second discharge start permission value, when the input voltage value of the main power supply device 3 is higher than a predetermined value based on the input voltage detection value of the input voltage detection means, the auxiliary power supply device 4 is in the middle of charging. Even in a state (a state where the storage capacity is not the upper limit value), the switch 9 is turned on to permit discharge of the auxiliary power supply device 4 and discharge from the auxiliary power supply device 4 to the auxiliary heating element 2b.

  Further, the control means 8 can discharge the voltage (or power) of the capacitor C below the first discharge start permission value and lower than the second discharge start permission value based on the voltage detection value of the auxiliary voltage detection means. When higher than the minimum voltage, based on the input voltage detection value of the input voltage detection means, when the input voltage value of the main power supply device 3 is lower than the predetermined value, only when the auxiliary power supply device is in the charged state of the storage capacity upper limit value The switch 9 is turned on to permit discharge of the auxiliary power supply 4 and discharge from the auxiliary power supply 4 to the auxiliary heating element 2b.

  If the input voltage of the main power supply device 3 is higher than the predetermined value, it can be determined that the amount of power supplied to the main heating element 2 of the main power supply device 3 is large. In such a case, the amount of power supplied to the auxiliary heating element 2b by discharging the capacitor C may be small. Therefore, when the input voltage value of the main power supply device 3 is higher than a predetermined value, the auxiliary power supply device 4 is allowed to discharge even if the auxiliary power supply device 4 is in the middle of charging (a state that is not the upper limit of the storage capacity). It is possible to eliminate the waiting time due to the charging of the auxiliary power supply device before the formation.

If the voltage of the main power supply 3 is lower than the predetermined value, it can be determined that the amount of power supplied to the main heating element 2 of the main power supply 3 is small. In such a case, the auxiliary heating element due to the discharge of the capacitor C If the amount of power supplied to 2b is not increased, the temperature of the fixing roller 40 does not rise sufficiently, and an image fixing failure in the fixing device 36 may occur. Accordingly, when the input voltage value of the main power supply device 3 is lower than the predetermined value, the auxiliary power supply device 4 is turned on only when the auxiliary power supply device 4 is in the charged state of the storage capacity upper limit value to permit the discharge of the auxiliary power supply device 4. Fixing failure can be prevented.
By such discharge control of the auxiliary power supply device 4, the discharge of the auxiliary power supply device can be optimized. Such discharge control of the auxiliary power supply 4 is possible regardless of whether the main power supply 3 is an AC power supply or a DC power supply. The voltage values may be determined as appropriate through experiments. The same applies to each embodiment described below.

  Next, a second embodiment of the present invention will be described. In the second embodiment, in the first embodiment, the determination information is information on the temperature of the pressure roller 41 as a pressure member. As temperature detecting means for detecting the temperature of the pressure roller 41, means such as various known temperature sensors may be employed. The control means 8 controls the switch 9 based on the temperature detection value of the temperature detection means to permit the discharge of the auxiliary power supply device 4. For example, the controller 8 allows the second discharge start permission that the voltage (or power) of the capacitor C is less than the first discharge start permission value and higher than the lowest dischargeable voltage based on the voltage detection value of the auxiliary voltage detector. When the temperature is higher than the value, when the temperature of the pressure roller 41 is higher than a predetermined value based on the temperature detection value of the temperature detection means, the auxiliary power supply device 4 is in the middle of charging (a state that is not the storage capacity upper limit value). Also, the switch 9 is turned on to allow the auxiliary power supply 4 to discharge, and the auxiliary power supply 4 discharges to the auxiliary heating element 2b.

  Further, the control means 8 can discharge the voltage (or power) of the capacitor C below the first discharge start permission value and lower than the second discharge start permission value based on the voltage detection value of the auxiliary voltage detection means. When the voltage is higher than the minimum voltage, the switch 9 is turned on only when the auxiliary power supply 4 is in the charged state of the storage capacity upper limit value when the temperature of the pressure roller 41 is lower than the predetermined value based on the temperature detection value of the temperature detection means. The auxiliary power supply device 4 is allowed to be discharged and discharged from the auxiliary power supply device 4 to the auxiliary heating element 2b.

  When the temperature of the pressure roller 41 is higher than a predetermined value, for example, when continuous image formation is performed by continuously passing the image through the image forming apparatus, the temperature of the pressure roller 41 becomes sufficiently high. In such a case, since the amount of heat from the fixing roller 40 taken away by the pressure roller 41 is small, the amount of power supplied to the auxiliary heating element 2b by the discharge of the capacitor C may be small. Therefore, when the temperature of the pressurizing member 41 is higher than the predetermined value, the auxiliary power supply 4 is allowed to discharge even when the auxiliary power supply 4 is in the middle of charging (a state where the storage capacity is not the upper limit value of the storage capacity). It is possible to eliminate the waiting time due to the charging of the auxiliary power supply device before.

Conversely, when the temperature of the pressure roller 41 is lower than the predetermined value, the heat of the fixing roller 40 causes the temperature of the pressure roller 41 to be increased unless the amount of power supplied to the auxiliary heating element 2b due to the discharge of the capacitor C is increased. The temperature of the fixing roller 40 is not sufficiently increased, and an image fixing defect in the fixing device 36 may occur. Therefore, fixing failure can be prevented by permitting discharge of the auxiliary power supply 4 only when the temperature of the pressure roller 41 is lower than the predetermined value and the auxiliary power supply is in the charged state of the storage capacity upper limit value.
By such discharge control of the auxiliary power supply device 4, the discharge of the auxiliary power supply device can be optimized.

  Next, a third embodiment of the present invention will be described. In the third embodiment, in the first embodiment, the determination information includes the environmental temperature of the heating device 1, the fixing device 36, and the image forming apparatus detected by the environmental temperature detection unit, for example, the fixing roller 40 and the pressure roller 41. Nip temperature etc. Of course, since the temperature of the nip portion N between the fixing roller 40 and the pressure roller 41 is difficult to measure, the environmental temperature in the third embodiment is the internal temperature of the heating device 1, the fixing device 36, or the image forming apparatus. Not only can the external temperatures of these devices be considered. In any case, it is possible to set all of the determination information to be detected by such a temperature that affects or is considered to affect the fixing of the image in the fixing device 36.

  The control means 8 controls the switch 9 based on the temperature detection value of the environmental temperature detection means to permit the discharge of the auxiliary power supply device 4. For example, the control unit 8 may start the second discharge in which the voltage (or power) of the capacitor C is less than the first discharge start permission value and higher than the lowest dischargeable voltage based on the voltage detection value of the auxiliary voltage detection unit. When the temperature is higher than the permitted value, the switch is turned on even when the auxiliary power supply 4 is in the middle of charging (not the upper limit of the storage capacity) when the environmental temperature is higher than a predetermined value based on the temperature detection value of the environmental temperature detection means. 9 is turned on to permit discharge of the auxiliary power supply 4 and discharged from the auxiliary power supply 4 to the auxiliary heating element 2b.

Further, the control means 8 can discharge the voltage (or power) of the capacitor C below the first discharge start permission value and lower than the second discharge start permission value based on the voltage detection value of the auxiliary voltage detection means. When the voltage is higher than the minimum voltage, the switch 9 is switched only when the temperature of the pressure roller 41 is lower than the predetermined value and the auxiliary power supply 4 is in the charged state of the storage capacity upper limit value based on the temperature detection value of the environmental temperature detection means. Is turned on to allow discharge of the auxiliary power supply 4 and discharge from the auxiliary power supply 4 to the auxiliary heating element 2b.
The reason why the discharge control of the auxiliary power supply device 4 is performed according to the environmental temperature as described above is the same as the reason why the discharge control of the auxiliary power supply device 4 is performed according to the temperature of the pressure roller 41 in the second embodiment.

Next, Reference Embodiment 1 of the present invention will be described. In the Reference Embodiment 1, in the first embodiment, the determination information is a fixing sheet passing number of the previous job in the fixing device 36 (the number of recording medium P passing through the fixing device 36). Various known means such as a paper passing counter may be employed as the fixing paper passing number detecting means for detecting the number of fixed paper passing. The control unit 8 controls the switch 9 based on the detected value of the number of sheets to be passed through the fixing sheet passing number detection unit to allow the auxiliary power supply device 4 to discharge. For example, the control unit 8 may start the second discharge in which the voltage (or power) of the capacitor C is less than the first discharge start permission value and higher than the lowest dischargeable voltage based on the voltage detection value of the auxiliary voltage detection unit. If it is higher than the permitted value, the auxiliary power supply 4 is in the middle of charging (not the storage capacity upper limit value) when the number of fixed sheets to be passed is larger than a predetermined value based on the detected number of sheets to be fixed by the fixing sheet passing number detecting means. In the state), the switch 9 is turned on to allow the auxiliary power supply 4 to discharge, and the auxiliary power supply 4 discharges to the auxiliary heating element 2b.

Further, the control means 8 can discharge the voltage (or power) of the capacitor C below the first discharge start permission value and lower than the second discharge start permission value based on the voltage detection value of the auxiliary voltage detection means. If the voltage is higher than the minimum voltage, only when the number of fixed sheets to be passed is less than the predetermined value based on the detected value of the number of sheets to be passed through the fixing sheet passing number detection means, and only when the auxiliary power supply is in the charged state of the storage capacity upper limit value The switch 9 is turned on to permit discharge of the auxiliary power supply 4 and discharge from the auxiliary power supply 4 to the auxiliary heating element 2b.
If the number of sheets to be fixed in the previous job in the fixing device 36 is larger than a predetermined value, the temperature of the pressure roller 41 is sufficiently high. As in the case of controlling the discharge of the power supply device 4, the amount of power supplied to the auxiliary heating element 2b due to the discharge of the capacitor C may be small, and the charging time can be shortened.

Next, Reference Embodiment 2 of the present invention will be described. In this reference embodiment 2, in the first embodiment, the determination information, the time interval between the previous job and the current job in the fixing device 36. As the job time interval detecting means for detecting the time interval between the previous job and the current job in the fixing device 36, various known means such as a timer may be employed.

  The control unit 8 controls the switch 9 based on the detection value of the job time interval detection unit to permit the auxiliary power supply device 4 to discharge. For example, the controller 8 allows the second discharge start permission that the voltage (or power) of the capacitor C is less than the first discharge start permission value and higher than the lowest dischargeable voltage based on the voltage detection value of the auxiliary voltage detector. If the value is higher than the value, the auxiliary power supply 4 is in the middle of charging when the time interval between the previous job and the current job in the fixing device 36 is shorter than a predetermined value based on the detection value of the job time interval detection means. Even in a state where the storage capacity is not the upper limit value, the switch 9 is turned on to permit discharge of the auxiliary power supply device 4 and discharge from the auxiliary power supply device 4 to the auxiliary heating element 2b.

Further, the control means 8 can discharge the voltage (or power) of the capacitor C below the first discharge start permission value and lower than the second discharge start permission value based on the voltage detection value of the auxiliary voltage detection means. When the voltage is higher than the minimum voltage, the auxiliary power supply device sets the upper limit of the storage capacity based on the detection value of the job time interval detection means when the time interval between the previous job and the current job in the fixing device 36 is longer than the predetermined value. Only in the value charging state, the switch 9 is turned on to allow the auxiliary power supply 4 to be discharged and discharged from the auxiliary power supply 4 to the auxiliary heating element 2b.
If the time interval between the previous job and the current job in the fixing device 36 is shorter than the predetermined value, the temperature of the pressure roller 41 is high. Therefore, according to the temperature of the pressure roller 41 in the second embodiment. As in the case of controlling the discharge of the auxiliary power supply device 4, the amount of power supplied to the auxiliary heating element 2b due to the discharge of the capacitor C may be small, and the charging time can be shortened.

Next, Reference Embodiment 3 of the present invention will be described. In this reference mode 3 , in the first embodiment, the determination information is the operation time of the previous job in the fixing device 36. Various known means such as a timer may be employed as the previous job operation time detection means for detecting the operation time of the previous job in the fixing device 36. The control unit 8 controls the switch 9 based on the detection value of the previous job operating time detection unit to permit the discharge of the auxiliary power supply device 4. For example, the control unit 8 starts the second discharge when the voltage (or power) of the capacitor C is less than the first discharge start permission value and higher than the lowest dischargeable voltage based on the voltage detection value of the auxiliary voltage detection unit. When the value is higher than the permitted value, the auxiliary power supply 4 is in the middle of charging (not the storage capacity upper limit value) when the previous job operating time is longer than a predetermined value based on the detected value of the previous job operating time detecting means. Even if it exists, the switch 9 is turned on to allow the auxiliary power supply 4 to discharge, and the auxiliary power supply 4 discharges to the auxiliary heating element 2b.

Further, the control means 8 can discharge the voltage (or power) of the capacitor C below the first discharge start permission value and lower than the second discharge start permission value based on the voltage detection value of the auxiliary voltage detection means. When the voltage is higher than the minimum voltage, the switch 9 is turned on only when the auxiliary power supply is in the charged state of the storage capacity upper limit when the previous job operating time is shorter than the predetermined value based on the detected value of the previous job operating time detecting means. The auxiliary power supply device 4 is allowed to be discharged and discharged from the auxiliary power supply device 4 to the auxiliary heating element 2b.
If the operation time of the previous job in the fixing device 36 is longer than the predetermined value, the temperature of the pressure roller 41 is high. Therefore, according to the temperature of the pressure roller 41 in the second embodiment, the auxiliary power supply device 4 Similar to the case where the discharge control is performed, the amount of power supplied to the auxiliary heating element 2b due to the discharge of the capacitor C may be small, and the charging time can be shortened.

  In each of the embodiments described above, the discharge control of the auxiliary power supply device 4 according to the input voltage value of the main power supply device 3, the discharge control of the auxiliary power supply device 4 according to the temperature of the pressure roller 41, and the auxiliary according to the environmental temperature. Discharge control of the power supply device 4, discharge control of the auxiliary power supply device 4 according to the number of sheets passing through the previous job in the fixing device 36, assistance according to the time interval between the previous job and the current job in the fixing device 36 The discharge control of the power supply device 4 and the discharge control of the auxiliary power supply device 4 according to the operation time of the previous job in the fixing device 36 may be implemented in any combination. In each of the embodiments, the discharge control of the capacitor C is performed by the control unit 8 provided in the heating device 1. However, the present invention is not limited to this, and the fixing device 36 or the image forming apparatus provided with the same. The control means may be provided to control the discharge of the capacitor C by the control means, and in any case, a dedicated control means for controlling the discharge of the capacitor C may be provided. You may make it also use a control means.

  In the embodiment described above, the nip portion is formed by two rollers, that is, the fixing roller 40 and the pressure roller 41. However, the fixing device of the present invention and the image forming apparatus using the same are as described above. Various configurations such as a type in which the recording medium P passes through or in close contact with the object to be heated, such as a roller and belt, a belt and a belt forming a nip portion, can be adopted. is there. The present invention is not limited to the illustrated type of image forming apparatus. For example, the photosensitive member is not a drum but a belt type, and a color image forming apparatus using an intermediate transfer belt. Applicable. Furthermore, the problem is more serious not only in the case of using a capacitor as an auxiliary power supply device but also in the case of using a secondary battery, and the solution can be achieved by the above configuration. Absent. Note that in the case of a device with a substantially constant output voltage such as a secondary battery, the vertical axis in FIGS. 4B and 4C is not the capacitor voltage but the remaining power storage amount.

It is sectional drawing which shows Embodiment 1 of this invention. FIG. 2 is a cross-sectional view illustrating a configuration of a fixing device according to the first embodiment. It is a circuit diagram which shows the structure of the heating apparatus of Embodiment 1. It is a figure which shows the change of the electric power used of the same Embodiment 1, and the voltage change of the capacitor C. FIG. FIG. 6 is a diagram illustrating a temperature change of the fixing roller according to the first embodiment. It is a figure which shows the voltage change from the discharge stop state of the capacitor of the same Embodiment 1 to charge start, full charge (charge stop), and voltage drop by discharge.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating device 2 Heating part 2a Main heating element 2b Auxiliary heating element 3 Main power supply device 4 Auxiliary power supply device 5 Switch 6 Charger 7 Switching device 8 Control means 9 Switch 10 CPU
DESCRIPTION OF SYMBOLS 11 Reading unit 12 Image forming part 13 Automatic document conveying apparatus 14 Document discharge tray 36 Fixing apparatus P Recording medium T Toner

Claims (8)

In an image forming apparatus having a main power supply device, an auxiliary power supply device, and a fixing device,
The auxiliary power supply device has a chargeable / dischargeable power storage device,
The fixing device includes a heating unit to which power is supplied from the main power supply device and the auxiliary power supply device,
When the fixing device is started up or when the recording medium is continuously passed through the fixing device, if the voltage, power, or amount of electricity stored in the power storage device is equal to or higher than a first discharge start permission value, the discharge of the power storage device Allow
The second discharge start permission when the voltage, power, or stored amount of the power storage device is less than the first discharge start permission value at the time of starting up the fixing device or continuously passing the recording medium through the fixing device. When the input voltage value of the main power supply device is higher than a predetermined value when the value is equal to or greater than the value, discharging of the power storage device is permitted even when the power storage device is in the middle of charging. . In an image forming apparatus having a main power supply device, an auxiliary power supply device, and a fixing device,
The auxiliary power supply device has a chargeable / dischargeable power storage device,
The fixing device includes a heating unit to which power is supplied from the main power supply device and the auxiliary power supply device,
When the fixing device is started up or when the recording medium is continuously passed through the fixing device, if the voltage, power, or amount of electricity stored in the power storage device is equal to or higher than a first discharge start permission value, the discharge of the power storage device Allow
The second discharge start permission when the voltage, power, or stored amount of the power storage device is less than the first discharge start permission value at the time of starting up the fixing device or continuously passing the recording medium through the fixing device. If the temperature of the pressure member of the fixing device is higher than a predetermined value when the value is equal to or higher than the value , the image forming device is characterized in that discharge of the power storage device is permitted even when the power storage device is in the middle of charging. apparatus. In an image forming apparatus having a main power supply device, an auxiliary power supply device, and a fixing device,
The auxiliary power supply device has a chargeable / dischargeable power storage device,
The fixing device includes a heating unit to which power is supplied from the main power supply device and the auxiliary power supply device,
When the fixing device is started up or when the recording medium is continuously passed through the fixing device, if the voltage, power, or amount of electricity stored in the power storage device is equal to or higher than a first discharge start permission value, the discharge of the power storage device Allow
The second discharge start permission when the voltage, power, or stored amount of the power storage device is less than the first discharge start permission value at the time of starting up the fixing device or continuously passing the recording medium through the fixing device. An image forming apparatus characterized in that when the environmental temperature of the fixing device is higher than a predetermined value when the value is equal to or higher than the value, discharging of the power storage device is permitted even when the power storage device is in the middle of charging . The image forming apparatus according to claim 1,
When the voltage or power of the power storage device or the power storage amount is lower than the second discharge start permission value and equal to or higher than the minimum dischargeable voltage, and when the input voltage value of the main power supply device is higher than a predetermined value An image forming apparatus, wherein discharging of the power storage device is permitted even when the power storage device is being charged . The image forming apparatus according to claim 2, wherein the voltage, power, or storage amount of the power storage device is lower than the second discharge start permission value and equal to or higher than a minimum dischargeable voltage, and the temperature of the pressure member is An image forming apparatus, wherein if the power storage device is higher than a predetermined value, discharging of the power storage device is permitted even when the power storage device is being charged . The image forming apparatus according to claim 3, wherein the voltage, power, or storage amount of the power storage device is lower than the second discharge start permission value and equal to or higher than a minimum dischargeable voltage, and the environmental temperature is a predetermined value. An image forming apparatus characterized in that discharge of the power storage device is permitted even when the power storage device is being charged when the power is higher . The image forming apparatus according to claim 1, wherein the power storage device is a capacitor . The image forming apparatus according to any one of claims 1 to 6, the image type forming apparatus, wherein the energy storage device is a battery.

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