JP2005221745A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which the use efficiency of an electric condenser is improved, risetime is shortened, a copying speed is increased, and the total copying time is accordingly shortened. <P>SOLUTION: The image forming apparatus includes: a capacitor (electric condenser) 17 charged by a commercial power source; a heater (heating device) for generating heat by the supply of power from the commercial power source and the capacitor 17; a fixing roller (fixing member) heated with the heat of the heater; an accumulating-electricity detection part 18 for detecting the accumulating electric energy of the capacitor 17; and a charge/discharge control part (CPU: control part) 11A for controlling the charge/discharge of the capacitor 17. If the accumulating electric energy of the capacitor 17 is less than a risetime threshold at the risetime of the temperature of the fixing roller and if the accumulating electric energy is more than or equal to a charge allowing threshold which is set lower than the risetime threshold, the charge/discharge control part 11 charges the capacitor 17. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus including a fixing device system having a capacitor that supplies electric power to a heating unit.

  In recent image forming apparatuses such as copying machines, printers, and facsimiles, a toner image is formed on a recording medium such as transfer paper by an electrophotographic method, and then the toner is passed through a fixing device to heat the toner. In general, a toner image is fixed to the toner image.

  Further, in such a fixing device, the heat is generated by heating a roller or an endless belt due to heat generated by a heated body, and the toner is heated by bringing a fixing member such as the roller or the endless belt into contact with the recording medium. I have to. Here, the power supply to the heating element is generally from a commercial AC power supply, but recently, a fixing device system that supplies power to the heating element in combination with a capacitor has also been developed (see, for example, Patent Document 1). .)

  In other words, the image forming apparatus is required to shorten the total copying time from the start-up of the apparatus to the end of copying. However, the image forming apparatus is started up when the main power is turned on from the state where the fixing device system is not in operation. In this case, power is supplied to a plurality of heating elements from a commercial AC power supply and a condenser respectively, the fixing member is heated, and the temperature can be rapidly raised to the reload temperature, reducing the waiting time until the device can be used. As a result, the total copying time can be shortened.

JP 2002-174988 A

  However, since the image forming apparatus is configured so as to give top priority to ensuring image quality, in order to prevent a fixing failure, the sheet passing speed is lowered to lower than usual. In some cases, there are deficiencies in the control that leads to the proper use of the battery, and it may take a lot of copying time, and it may be difficult to shorten the total copying time.

  The present invention has been made in view of the above problems in the prior art, and by efficiently and appropriately controlling the usage form of the capacitor at the time of start-up and paper feeding, the start-up time is shortened and the copying speed is increased. An object of the present invention is to provide an image forming apparatus which can be enlarged to reduce the total copying time.

  In order to solve the above-mentioned problem, the invention described in claim 1 includes a capacitor charged by a commercial power source, a heater heated by being supplied with power from the commercial power source and the capacitor, and a fixing member heated by the heater. And an electricity storage detector that detects the energy stored in the capacitor, and in an image forming apparatus that heats an unfixed image to be fixed on a recording medium by the fixing member, when the temperature of the fixing member is raised When the stored energy of the capacitor is equal to or greater than a threshold, the controller includes a control unit that permits power supply from the capacitor to the heater, and the control unit is configured such that the stored energy of the capacitor is less than the threshold at the time of startup. And selecting either the case where charging from the commercial power source to the capacitor is not performed or the case where charging is performed based on the stored energy. That.

  According to a second aspect of the present invention, there is provided a battery that is charged by a commercial power source, a heater that is heated by being supplied with power from the commercial power source and the battery, a fixing member that is heated by the heater, and a stored energy of the battery In an image forming apparatus that heats an unfixed image by the fixing member and fixes it on a recording medium, when the temperature of the fixing member is raised, the stored energy of the capacitor is When it is equal to or higher than a startup threshold, the controller includes a control unit that permits power supply from the capacitor to the heater, and the control unit stores the storage energy of the capacitor during the startup. If the power storage energy is less than the threshold for charging permission set lower than the threshold for startup, the commercial power supply to the battery And permits the electrodeposition.

  According to a third aspect of the present invention, when the storage energy of the battery is less than the startup threshold and is equal to or higher than the charge permission threshold, the control unit may supply power from the commercial power source to the battery. In addition to permitting charging, the recording medium is made to wait until at least the stored energy reaches the startup threshold.

  According to a fourth aspect of the present invention, there is provided a battery that is charged by a commercial power source, a heater that is heated by being supplied with power from the commercial power source and the battery, a fixing member that is heated by the heater, and a stored energy of the battery. In an image forming apparatus that includes a power storage detection unit that detects an image and heats an unfixed image to be fixed on a recording medium by the fixing member, when a plurality of recording media pass continuously through the fixing member The storage unit includes a control unit that permits power supply from the storage unit to the heater when the storage energy of the storage unit is equal to or greater than a continuous sheet passing threshold, and the control unit stores the storage unit in the storage unit during the continuous sheet passing. When the energy is less than the threshold for continuous paper passing, either the case where charging from the commercial power source to the battery is not performed or the case where charging is performed is selected.

  According to a fifth aspect of the present invention, in the case where the storage energy of the battery is less than the threshold for continuous paper feeding and the battery is charged from the commercial power source, the control unit stores the energy stored in the battery. The recording medium is made to wait until the threshold for continuous paper passing is reached.

  The invention according to claim 6 includes a sheet number predicting unit that predicts a total number of recording media that pass through the fixing member during the continuous sheet passing, and the control unit stores the energy stored in the capacitor during the continuous sheet passing. If it is less than the threshold for continuous sheet passing, selecting whether to charge from the commercial power source to the battery or to charge based on the total number predicted by the sheet number predicting unit Features.

  In the invention according to claim 7, the control unit has a threshold value for starting charging set lower than the threshold value for continuous paper feeding, and compares the stored energy of the capacitor and the threshold value for starting charging. And as a result, either the case where charging from the commercial power source to the battery is not performed or the case where charging is performed is selected.

  The invention according to claim 8 includes a sheet number predicting unit that predicts the total number of recording media that pass through the fixing member during the continuous sheet passing, and the threshold value for starting charging is the total number predicted by the sheet number predicting unit. It is set by the number of sheets and the sheet passing speed of the recording medium.

  According to a ninth aspect of the present invention, an image reading unit that reads an image on a document is provided, and the number predicting unit predicts the total number of sheets based on document reading information of the image reading unit.

  According to a tenth aspect of the present invention, the number prediction unit predicts the total number of sheets based on print command information input from the outside.

  According to the present invention, it is possible to efficiently and appropriately control the usage form of a capacitor at the time of starting up an image forming apparatus including a fixing member and at the time of continuous copying by continuous paper feeding, and secondly, the capacitor. By effectively using the stored energy, the start-up time is shortened and the image fixing speed during continuous copying is increased, so that many continuous sheets can be passed at a higher CPM in a short time. As a result, the total copying time can be shortened as a whole, and an image forming apparatus that is easy for the user to use can be provided.

Below, the structure which becomes a premise of each embodiment of this invention is demonstrated.
FIG. 9 shows an example of the fixing device. 9 includes a fixing roller (fixing member) 91 that is heated by the heaters 93, 94a, and 94b, which is an aspect of the heating unit, and rotates in the clockwise direction in the drawing, and a constant nip pressure applied to the fixing roller 91. And a pressure roller (fixing member) 92 that rotates in the counterclockwise direction in the figure, and a temperature sensor (temperature detection unit) 95 that contacts the fixing roller 91 and detects the surface temperature thereof.

  The fixing roller 91 is normally a hollow cylindrical roller, but may be in the form of an endless belt. Further, the fixing device is in a stationary state when the fixing device starts up, and rotates in the clockwise direction in the drawing when the sheet P as a recording medium is passed.

  The pressure roller 92 is usually a cylindrical roller whose surface is made of an elastic member such as silicone rubber, but may be in the form of an endless belt. The pressing roller 92 is pressed against the fixing furnace 91 by being pressed toward the fixing roller 91 with a constant pressure by a pressing means (not shown). The pressure roller 92 is also stationary when the fixing device rises, and rotates in the counterclockwise direction in the drawing when the sheet P as a recording medium is passed. The rotation driving of the fixing roller 91 and the pressure roller 92 is performed by a driving mechanism (not shown).

  The heaters 93, 94a, and 94b are all disposed in the hollow portion of the fixing roller 91. However, the heaters 93, 94a, and 94b may be disposed so as to cover the upper portion of the fixing roller 91 as sheet-like heaters.

The heater 93 generates heat when power is supplied from an external power source such as a commercial power source, and heats the fixing roller 91 by the radiant heat.
The heaters 94a and 94b generate heat when electric power is supplied from the capacitor, and heat the fixing roller 91 by the radiant heat.
The heaters 93, 94 a, and 94 b generate heat when supplied with electric power and can heat the fixing roller 91, and there are no particular restrictions on the type of heater, and the heaters 93, 94 a, and 94 b can be arranged at any position where the fixing roller 91 is heated. It is.

  As long as the temperature sensor 95 is a thermometer that can detect the surface temperature of the fixing roller 91, a contact thermometer or a non-contact thermometer may be used.

  When the image forming process is performed in the image forming apparatus, the sheet P, which is a recording medium carrying the toner T that is an unfixed image by the electrophotographic method, passes through the nip portion between the heated fixing roller 91 and the pressure roller 92. At this time, the toner T is fixed to the sheet P by being heated by the fixing roller 91 and the pressure roller 92. At this time, predetermined heat is required for the toner T to be fixed to the sheet P, and for this reason, the heaters 93 and 94 are set so that the surface temperature of the fixing roller 91 becomes a reload temperature at which the toner T can be fixed. Power supply to is controlled.

  FIG. 10 shows a circuit configuration example of the fixing device system. In FIG. 10, a heater 93 generates heat by electric power supplied from an external power source (commercial power source) 86, and a heater 94 including heaters 94a and 94b generates heat by electric power supplied from a capacitor 87 which is one mode of a power storage unit. It has become. The heater 94 is preferably one in which a plurality of heaters are connected in parallel with the capacitor 87, and any one or all of these heaters may be connected to the capacitor 87 by switching a switch (not shown). For example, all heaters are connected to the capacitor 87 when the apparatus is started up, and any selected heater is connected when paper is passed.

  As the capacitor 87, it is preferable to use a capacitor such as an electric double layer capacitor having a large capacitance of the Farad order or more. In addition, a power storage detector 88 is connected to the capacitor.

  The capacitor voltage, which is an index of the stored energy (remaining power amount) of the capacitor 87 detected by the storage detector 88, and the temperature of the fixing roller 91 detected by the temperature detecting means 95 are respectively controlled through the input circuit as detection signals. CPU 81, which is one aspect of the unit. The CPU 81 energizes the heater 93 via the triac 83 and energizes the heater 94 via the FET 85 so that the surface temperature of the fixing roller 91 becomes a set temperature based on detection signals from the power storage detector 88 and the temperature sensor 95. Are controlled by controllers 82 and 84, respectively. The capacitor 87 is connected to the charging device 8a by the switch 89 and can be charged.

  FIG. 11 shows a block diagram relating to mode selection based on the capacitor voltage in the system. In FIG. 11, the CPU 81 includes a determination unit 81a and a mode selection unit 81b. Further, the determination unit 81a has a threshold value (discharge start threshold value) relating to a preset capacitor voltage, and the mode selection unit 81b permits the power supply from the capacitor 87 to the heater 94 when the apparatus is started up and during the sheet passing operation. There are a plurality of modes such as non-permission, power supply permission from the capacitor 87, and CPM (number of copies per minute) setting according to non-permission.

In the mode selection unit 81b shown in FIG. 11, the mode selection is performed as follows, for example.
(S81) A continuous copy command is issued by the copy start button.
(S82) The capacitor voltage of the capacitor 87 is detected by the power storage detection unit 88, and the detection signal is captured by the CPU 81.
(S83) In the determination unit 81a in the CPU 81, the detected capacitor voltage is compared with the threshold value, the magnitude is determined, and the determination result is sent to the mode selection unit 81b.
(S84) The mode selection unit 81b performs mode selection according to the determination result of step s83, and the operation of the image forming apparatus including the fixing device system is controlled based on the selected mode.

As modes selected in step s84, for example, the following modes are prepared.
(Mode 91) When the capacitor voltage detected at the start-up of the apparatus or at the time of continuous paper feeding is equal to or higher than the threshold, power supply from the capacitor 87 to the heater 94 is permitted, and CPM is set as a normal condition.
(Mode 92) When the detected capacitor voltage is less than the threshold, power supply from the capacitor 87 to the heater 94 is not permitted, and the CPM is reduced (down). In this case, it is impossible to supply power enough to compensate for the temperature drop of the fixing roller 91 due to continuous paper passing, and fixing failure occurs under normal conditions of the CPM. Therefore, the CPM is lowered to ensure image quality. is there.

FIG. 12 shows an operation example of the fixing device system when the capacitor voltage detected at the time of starting the apparatus is less than the threshold value. In this case, the preconditions are as follows.
・ Discharge start threshold (at the time of continuous paper feeding and discharging): 30V
-CPM normal conditions: 75 CPM
-CPM down condition: 40 CPM
-Copy command: 100 sheets continuously passed-Capacitor voltage at copy command: 27V

(S91) When a continuous copy command is issued by the copy start button, the capacitor voltage (27V) of the capacitor 87 is detected by the power storage detection unit 88, and the detection signal is captured by the CPU 81.
(S92) In the determination unit 81a, it is determined that the capacitor voltage (27V) is less than the threshold value (30V), and the determination result is sent to the mode selection unit 81b.
(S93) In the mode selection unit 81b, the power supply from the capacitor 87 to the heater 94 is not permitted, and the mode of the CPM down condition (40 CPM) is selected.
(S94) Power supply from the commercial power supply 86 to the heater 94 is started, the fixing roller 91 is heated, and 30s is required as a startup time. At this time, the capacitor 87 is in a standby state.
(S95) The temperature of the fixing roller 91 is detected by the temperature sensor 95, and it is determined whether or not the temperature of the fixing roller 91 has reached the reload temperature.
(S96) The sheet passing is started at 40 CPM, and the temperature of the fixing roller 91 is maintained only by the commercial power source 86, so that a good copy in the fixing state is possible. At this time, the capacitor 87 is in a standby state. Note that 150 s is required as the paper passing time. That is, the copy time for a total of 100 sheets at 40 CPM is 180 seconds when combined with the start-up time of 30 s.

As described above, even when the capacitor has a considerable amount of stored energy, if the charging voltage of the capacitor is less than the threshold value, the sheet passing speed is reduced and the stored power of the capacitor is not used. Image formation was taking, and it took time for copying.
The inventors have found that this problem occurs because the threshold value of the charging voltage is set so as not to cause a temperature drop regardless of the number of continuous sheets to be passed and the type of paper according to the specifications of the copying machine. As a result of careful attention and intensive studies, the present invention has been achieved to solve the above problems by efficiently utilizing capacitors.

  A first embodiment of an image forming apparatus according to the present invention will be described below. In the present embodiment, an example of starting up the image forming apparatus will be described, but the present invention is not limited to this.

FIG. 1 is a circuit diagram of a fixing device system according to the present invention.
The fixing device system 10 is basically the same as the premise of the embodiment of the present invention shown in FIG. 10 except for the operation of a CPU (corresponding to a control unit described in claims) 11. 10, the commercial power source 16 connected to the heater 93, the capacitor 17 connected to the heater 94 including the heaters 94 a and 94 b, the power storage detector 18 connected to the capacitor 17, and the commercial power source 16. The controller 12 and the triac 13 related to the control of the power supply of the power supply, the controller 14 related to the control of the power supply of the capacitor 17, the FET 15, the switch 19, and the charging device 1 a are provided. However, as the capacitor 17, for example, a bank configuration using 40 electric double layer capacitors of 2.5V per cell and a capacity of 500F is adopted as an example. For example, the heater 93 is rated at 900 W, the heater 94 a is rated at 1000 W, for example, and the heater 94 b is rated at 800 W, for example. The fixing device may be the same as that shown in FIG.

  FIG. 2 is a block diagram illustrating a functional configuration of a main part of the fixing device system 10 according to the present embodiment. The CPU 11 includes internal information such as ON / OFF information from the power-on switch Csw that instructs the start-up of the image forming apparatus 100, residual voltage information from the power storage detection unit 18, and temperature information of the fixing roller 91 from the temperature sensor 95. A charge / discharge control unit (corresponding to a control unit described in claims) 11A that is connected so as to be taken in by the identification unit Dd and controls charge / discharge of the capacitor 17 by operating an internal control execution unit Ca Is functionally configured.

  The charge / discharge control unit 11A detects the remaining power amount of the capacitor 17 after the power is turned on, and discharges from the capacitor 17 in comparison with a threshold value for start-up at which the capacitor 17 starts discharging and a threshold value for permitting charging. Is selected to generate heat from the heaters 94a and 94b, or to charge the capacitor 17 by supplying power from the commercial power supply 16. Further, after the charging, when the stored energy of the capacitor 17 reaches, for example, a threshold for startup, the capacitor 17 discharges the heaters 94a and 94b to allow the heaters 94a and 94b to generate heat.

  When the heat storage energy of the capacitor 17 is equal to or higher than the startup threshold, the charge / discharge control unit 11A discharges from the capacitor 17 and causes the heaters 94a and 94b to generate heat. On the other hand, when the heat storage energy of the capacitor 17 is less than the startup threshold value and is equal to or higher than the charge permission threshold value, the discharge control unit 11A charges the capacitor 17 from the commercial power supply 16 and then stores the heat storage heat energy. When, for example, a threshold value for start-up is reached, discharge is performed and the heaters 94a and 94b generate heat.

  In the case of this example, the maximum stored energy of the capacitor 17 is 100 V at maximum because of the bank configuration using 40 electric double layer capacitors of 2.5 V per cell, and the heaters 94a and 94b generate heat almost at maximum. Therefore, there is a mode in which the stored energy is 85 V, for example, and therefore, the threshold value for startup is set to 85 V, for example, and the threshold value for charging permission is set to 83 V, for example. However, these threshold values are arbitrarily set according to the size of the fixing device (fixing roller 91), the preset heat generation capability of the heater 93 that generates heat from an external power source, and the like.

  When power is supplied from the commercial power supply 16 to the capacitor 17 to increase the stored energy from, for example, the threshold 83V for charging permission to the threshold 85V for startup, if it takes 5 seconds to increase the stored energy by 1V, Although charging takes 10 s, it takes 10 s for the fixing roller 91 to reach the reload temperature by combining the heat generated by the heater 93 in advance and the heat generated by the heaters 94a and 94b after charging. It can be seen that a total time of 20 s is sufficient. This is because the start-up time of the fixing device shown in FIG. 12 requires 30 s as shown in the above (s94), so that the time can be reduced by 10 s.

Next, an operation example of the fixing device system of the present embodiment when the detected stored energy is less than the startup threshold will be described. In this case, the CPU 11 and the operation example of the charge / discharge control unit 11A functionally configured by the CPU 11 are also shown, and the precondition is as follows as an example.
-Start-up threshold A (preset threshold): 85V
-Charging permission threshold (preset threshold): 83V
-CPM normal conditions: 75 CPM
-CPM down condition: 40 CPM

(S11) When a continuous copy command is issued by the copy start button Csw, the storage energy of the capacitor 17 is detected by the storage detection unit 18, and the detection signal is captured by the CPU 11.
(S12) It is determined whether or not the stored energy is equal to or higher than a threshold for starting up, and whether or not it is equal to or higher than a threshold for charging permission.
(S13) When it is determined that the stored energy is less than the threshold value for permitting charging, only the heater 93 is heated by the electric power from the commercial power supply 16, and the temperature of the fixing roller 91 is detected by the temperature sensor 95.
(S14) When it is determined that the heat storage energy is equal to or higher than the startup threshold, the heater 93 is heated by the electric power from the commercial power source 16, and the heaters 94a and 94b are discharged from the capacitor 17 by heating. 94 a and 94 b generate heat, and the temperature sensor 95 detects the temperature of the fixing roller 91. In this case, since each heater 93, 94a, 94b generates heat with the maximum capacity at the same time, the reload temperature is reached in 10 seconds.
(S15) When it is determined that the heat storage energy is less than the startup threshold and greater than or equal to the charging permission threshold, the capacitor 17 is charged by supplying power from the commercial power supply 16 to the capacitor 17. At the same time, the stored energy is detected. In order for the stored energy to reach the rising threshold value of 85V, a boost of 2V is required, and when a boost of 1V requires 5 s, a total of 10 s is required.
(S16) When the stored energy reaches the threshold level for startup, the heater 93 is heated by the electric power from the commercial power source 16, and the heaters 94a and 94b are discharged from the capacitor 17 to cause the heaters 94a and 94b. The temperature sensor 95 detects the temperature of the fixing roller 91. It takes 10 seconds for the fixing roller 91 to reach the reload temperature because the heaters 93, 94a and 94b generate heat at the maximum capacity at the same time.
(S17) When it is detected by the temperature sensor 95 that the temperature of the fixing roller 91 has reached the reload temperature, power supply from the commercial power supply 16 to the heater 93 is restricted, and the heater 93 enters a driving state during preheating. At the same time, the discharge from the capacitor 17 to the heaters 94a and 94b is stopped, and the heaters 94a and 94b stop driving. Finally, the fixing roller 91 reaches the reload temperature by adding the charging time of 10 s and the heating time of 10 s, that is, the time of 20 s. Therefore, the start-up time of the fixing device shown in FIG. Compared to the time required for 30 s as shown in s94), the time can be reduced by 10 s.
(S18) Next, it becomes possible to copy a predetermined image (fix an unfixed image) onto the sheet P as a recording medium.

  When the copy start button Csw is turned on, the CPU 11 controls the fixing roller 91 and the like to be in a standby state until the temperature of the fixing roller 91 reaches the reload temperature so that the copying operation cannot be performed.

  In the present embodiment, the CPU (control unit) 11 is configured such that the stored energy is lower than the startup threshold even when the stored energy of the capacitor 17 is lower than the startup threshold during startup. If it is equal to or higher than the set charging permission threshold, the heaters 93, 94a, 94b are heated at the same time after being charged by supplying power from the commercial power source 16 to the capacitor 17, thereby causing the fixing roller 91 to be reloaded. As a result, the start-up time of the fixing roller 91 can be greatly shortened as compared with the premise of the present invention.

  Next, FIG. 3 shows a configuration example in which the fixing device system 10 of the present embodiment is incorporated in an image forming apparatus. In the image forming apparatus 100 shown in FIG. 3, a drum-shaped photosensitive member 101 as an image carrier, a charging unit 102 that uniformly charges the photosensitive member 101, and a laser beam L is exposed on the charged photosensitive member 101. The laser optical system 140 that forms an electrostatic latent image and the developing unit 107 that develops the electrostatic latent image on the photosensitive member 101 into a toner image constitutes an electrophotographic mechanism. In addition, the toner image on the photosensitive member 101 is transferred to the sheet P supplied from the paper feeding cassette 110 by the transfer unit 106, and the sheet P on which the toner image is formed is conveyed to the fixing device system 10 and added to the fixing roll 91. The toner is fixed to the sheet P by being heated by the pressure roll 92.

  In the image forming apparatus 100, when the main power is turned on, each part of the image forming apparatus 100 is activated, and the fixing device system 10 is also started up. Electricity supply to the heaters 93 and 94 of the fixing device is started, and the fixing roller 91 is heated and enters a standby state. Then, when print command information is input by external input, the power supply control of the present invention described above is performed. That is, even if the stored energy of the capacitor does not reach the startup threshold value, but is higher than the charging permission threshold value, the charge / discharge control unit 11A supplies power from the commercial power supply 16 to the capacitor 17. And go to the charging process. For example, when the stored energy reaches a threshold value for starting up, the CPU 11 causes the heater 93 of the fixing device to generate heat, and the charge / discharge control unit 11A configured by the CPU 11 discharges from the capacitor 17 to cause the heaters 94a and 94b to turn on. The fixing roller 91 is heated with high efficiency by generating heat. Thus, when the temperature of the fixing roller 91 reaches the reload temperature, the standby state of each part is canceled and an image forming operation can be performed.

  Also in this case, the use efficiency of the capacitor 17 can be improved and the time until the fixing roller 91 reaches the reload temperature can be shortened. Therefore, the image forming operation is easy for the user having a short start-up time and a high copying speed. It can be a device.

  The second embodiment of the image forming apparatus according to the present invention will be described below. In the present embodiment, an example of continuous paper passing of the image forming apparatus will be described, but the present invention is not limited to this.

  In the case of the present embodiment, the overall configuration is basically the same as in the case of the first embodiment, but the charge / discharge control unit functionally configured by the CPU 11 (the control unit described in the claims) The control mode of 11B is different from the control mode of the charge / discharge control unit 11A, and the standby state of the copy operation when the CPU 11 continuously passes the sheet P as a plurality of recording media through the fixing member. There is a difference in that the standby control unit 11C (corresponding to the control unit described in the claims) 11C is functionally configured. Therefore, detailed description of other configurations is omitted.

  FIG. 4 is a block diagram illustrating a functional configuration of a main part of the fixing device system 10 according to the present embodiment. The CPU 11 displays ON / OFF information from the copy start switch Csw, for example, copy number information from the copy number designation numeric keypad Tke, remaining voltage information from the power storage detection unit 18, and temperature information of the fixing roller 91 from the temperature sensor 95. The charging / discharging control unit 11B that controls the charging / discharging of the capacitor 17 during continuous paper feeding by operating the internal control execution unit Ca is functionally configured while being connected to the internal information identification unit Dd. In addition, the standby control unit 11C that controls the standby state of the fixing device system 10 at the time of continuous paper passing (hereinafter, when continuous paper passing is described is intended to start copying of continuous paper) is functionally configured. Is.

  The charge / discharge control unit 11B permits the power supply from the capacitor 17 to the heaters 94a and 94b when the stored energy of the capacitor 17 is equal to or greater than the threshold for continuous paper passing during continuous paper feeding. Further, the charge / discharge control unit 11B compares the stored energy of the capacitor 17 with the threshold value for starting charging set lower than the threshold value for continuous sheet passing, and the stored energy is less than the threshold value for continuous sheet passing; If it is equal to or more than the threshold value for starting charging, the power supply from the commercial power supply 16 to the capacitor 17 is permitted and the capacitor 17 is charged.

  The threshold for continuous paper passing differs depending on the type of the image forming apparatus, that is, the fixing device system 10, but when continuously passing a predetermined number of sheets P, the heat of the heaters 94 a and 94 b is added to the heat of the heater 93. Thus, it is set so that copying without image quality deterioration can be performed at a high CPM, and for example, 30 V, 40 V, or the like is set. In this example, the case where the former 30V is applied to the threshold for continuous paper feeding is illustrated. The threshold 30V for continuous paper passing is premised on that if the stored energy (remaining power amount) of the capacitor 17 is 30V, it can correspond to a high copy number (number of paper passes) and a high CPM (paper feed speed). It is the value made. From this relationship, when the number of copies is very large, a higher voltage may be set according to the number of copies and CPM.

  The threshold value for starting charging is set in consideration of the number of copies (number of sheets to be passed) and CPM (sheet passing speed) every time continuous feeding is performed (that is, at the start of copying of continuous feeding). A value lower than the threshold for passing paper is set. That is, the threshold value for starting charging is the total amount of time until the voltage of the capacitor 17 reaches the threshold value for continuous paper feeding due to charging from the commercial power supply 16 as compared to the preset continuous paper feeding threshold value for the current stored energy. Even if the charging time T is taken into consideration, a value is set that shortens the copying time for all sheets. In this example, when the threshold for continuous paper passing is 30V, for example, 27V is set as the threshold for charging start. For example, when it takes 5 s for the voltage of the capacitor 17 to increase by 1 V due to charging, if the stored energy is 27 V, it takes 15 s to reach 30 V.

That is, when I = 1V · 5A charging,
t = C · V / I = 25 · 1/5 = 5 _{(S / V)}
So when charging 3V,
T = V · t = 3.5 · 15 _(S)
It becomes. Here, t is a unit charging time, C is a capacitance of the capacitor 17, V is a voltage, I is a current, and T is a total charging time.

  Even over the total charging time T of 15 s, it is possible to set to a high CPM (for example, 75 CPM), and thereby fixing an unfixed image on each sheet P with high continuous paper passing in a short time. This is possible with image quality.

  For example, the threshold value for starting charging can be set by using the number of copies (sheet passing number) and CPM (sheet passing speed). This can be obtained by calculation each time or starting from one sheet. A threshold value for starting charging, which is appropriately applied from a table or the like in which a threshold value for starting charging of each predetermined value corresponding to each relationship between each copy number (number of passing sheets) and each CPM (sheet passing speed) is recorded, is set. There are cases where it is determined each time by selecting. However, any other method may be used as a method for determining the threshold value for starting charging.

  The standby control unit 11C, for example, charge / discharge control when charging the capacitor 17 from a threshold 27V for charging permission to a threshold 30V for continuous paper passing, for example, during continuous paper passing for which the number of copies has been determined by the operation of the numeric keypad Tke or the like. The time information indicating the total charge time, for example, 15 s, which is apparent from the above calculation, is acquired from the notification function of the unit 11B or the CPU 11, and the total time of the total charge time, for example, 15 s and the startup time (see FIG. 5) 30 s, for example, 45 s In the meantime, the state of each unit including the fixing device system 10 is set to a standby state (paper passing standby state). The standby control unit 11C includes, for example, a timer. For example, when a total standby time of 45 s elapses, the standby control unit 11C cancels the standby state of each unit including the fixing device system 10 and enables the continuous copy operation of continuous paper feeding.

Next, an example of the operation of the fixing device system according to the present embodiment when the detected stored energy is less than the threshold for continuous paper passing will be described with reference to FIG. In this case, the CPU 11, the charge / discharge control unit 11 </ b> B functionally configured by the CPU 11, and the standby control unit 11 </ b> C are also shown as examples of operation, and the precondition is as follows as an example.
-Continuous paper feeding: 100 sheets-Threshold for continuous paper feeding (preset threshold): 30V
-Charging start threshold (for example, threshold set in calculation): 27V
-CPM normal conditions: 75 CPM
-CPM down condition: 40 CPM

(S21) The copy start button Csw is pressed, and the copy number information (100 sheets) input from the numeric keypad Tke is acquired.
(S22) The state of each unit including the fixing device system 10 is set to a standby state.
(S23) The minimum threshold voltage for starting charging that can shorten the total copy time (total copy time) compared to the CPM down condition based on the copy number information (100 sheets) and the CPM normal condition (75 CPM) For example, by calculation, and the current stored energy of the capacitor 17 is detected. As a result of the calculation, the threshold value for starting charging is exemplified as 27V.
(S23) The threshold 30V for continuous paper passing and the threshold 27V for starting charging are compared with the current stored energy of the capacitor 17 to determine whether the current stored energy is higher or lower than the threshold 27V for starting charging. To do.
(S24) When the threshold value 27V for starting charging is compared with the current stored energy of the capacitor 17, and the current stored energy value is lower than the threshold value 27V for starting charging, for example, the total charging time 0 s is calculated. And the time information indicating the total charging time 0 s is output to the standby control unit 11C. As a result, the standby control unit 11C cancels the standby state of each unit including the fixing device system 10. This means that an unfixed image is fixed on each sheet P by the fixing roller 91 that is heated only by the heat generated by the heater 93 that receives power supply from the commercial power supply 16 during the continuous copying operation of continuous paper passing. The operation of the fixing device system 10 in this case is the same as the operation in the case of the configuration as the premise of the present invention shown in FIG. The total copy time in this case is 180 s including the start-up time 30 s.

(S25) On the other hand, the threshold value 27V for charging start and the threshold value 30V for continuous paper passing are compared with the current stored energy of the capacitor 17, and the value of the current stored energy is equal to, for example, the threshold value 27V for starting charging. In this case, for example, the total charging time 15s is obtained by calculation, and time information indicating the total charging time 15s is output to the standby control unit 11C. The standby control unit 11C starts counting the time interval of the startup time 45s obtained by adding the startup time 30s to the total charging time 15s.
(S26) When it is detected that the total charge time 15s has elapsed and the current stored energy of the capacitor 17 has become equal to, for example, the continuous paper passing threshold 30V, the process proceeds to the next startup operation. That is, power is supplied from the commercial power supply 16 to the heater 93 to cause the heater 93 to generate heat, and the fixing roller 91 is efficiently heated by this heat generation. Also in this case, the startup time, that is, the heat generation duration of each heater 93 is 30 s as shown in FIG.
(S27) Thus, when the total operation time 45s of the total charging time 15s and the startup time 30s elapses and the startup operation ends, the standby control unit 11C counts the elapsed time of 45s, and the fixing device system 10 and each unit. Cancel the standby state.
(S28) The continuous copying operation with 100 continuous sheets is started. In this continuous copying operation, the sheets P are sequentially conveyed at 75 CPM between the fixing roller 91 and the pressure roller 92 heated by the heaters 93, 94a, and 94b. Since the heat generated from 94b is also received, the reload temperature is reliably maintained without causing a temperature drop due to the passage of each sheet P, and the unfixed image can be fixed on each sheet P reliably and with high quality. The total time for all copying operations for 100 consecutive sheets is 80 s, and the total charging time 15 s and the start-up time 30 s are 125 s. Since the total copy time in the configuration as the premise of the present invention shown in FIG. 12 was 180 s, it was possible to shorten the time by 55 s.

  In this embodiment, since the charge / discharge control unit 11B and the standby control unit 11C are provided, a fixed image can be obtained even if the number of sheets to be passed and the CPM are set high during continuous sheet passing to reduce the total time for all copying operations. In other words, it is possible to reduce the continuous copying time during continuous paper feeding and to increase the copying speed during continuous paper feeding compared with the configuration which is the premise of the present invention. , User-friendliness is improved in each stage.

  A configuration example in which the fixing device system 10 according to the present embodiment is incorporated in an image forming apparatus is basically the same as that shown in FIG. 3, and detailed description thereof is omitted. When print command information is input by an external input, the power supply control of the present invention described above is performed. That is, even if the stored energy of the capacitor does not reach the threshold for continuous sheet passing, but is higher than the threshold for charging start set based on the number of sheets that have been input, the charge / discharge control unit 11B Power is supplied from the commercial power supply 16 to the capacitor 17 and the charging process is started. When the stored energy reaches, for example, a threshold for continuous paper passing, the CPU 11 causes the heater 93 of the fixing device to generate heat and starts up the device. Next, the CPU 11 generates heat from the heater 93 of the fixing device, and the charge / discharge control unit 11B configured by the CPU 11 discharges from the capacitor 17 and also generates heat from the heater 94a or 94b. Heat with efficiency. Thus, it is possible to perform a continuous copy operation under the CPM normal condition.

  In this case as well, it is possible to improve the utilization efficiency of the capacitor 17 and increase the copy speed after the fixing roller 91 reaches the reload temperature. For this reason, the number of copies that can be processed at the same time as the copy speed is increased. An image forming apparatus that can be easily increased, is extremely fast, and is easy to use for the user can be obtained.

  The third embodiment of the image forming apparatus according to the present invention will be described below. This embodiment shows an example in which a threshold value for starting charging is set at the time of continuous paper feeding (at the time of continuous paper copying start) in an image forming apparatus provided with a sheet number predicting unit. However, the present invention is not limited to this.

First, before describing the present embodiment, FIG. 6 shows an operation example in the case where the capacitor voltage detected in the fixing device system as the premise of the present invention is less than the threshold value. In this case, the preconditions are as follows.
・ Threshold (when paper is passed): 30V
-CPM normal conditions: 75 CPM
-CPM down condition: 40 CPM
・ Copy command: 40 sheets continuously passed ・ Capacitor voltage at copy command: 27V

(S101) When a continuous copy command is issued by the copy start button, the capacitor voltage (27V) of the capacitor 87 is detected by the power storage detection unit 88, and the detection signal is captured by the CPU 81.
(S102) In the determination part 81a, it determines with a capacitor voltage (27V) being less than a threshold value (30V), and a determination result is sent to the mode selection part 81b.
(S103) In the mode selection unit 81b, the power supply from the capacitor 87 to the heater 94 is not permitted, and the mode of the CPM down condition (40 CPM) is selected.
(S104) Power supply from the commercial power supply 86 to the heater 94 is started, the fixing roller 91 is heated, and 30s is required as a startup time. At this time, the capacitor 87 is in a standby state.
(S105) The sheet passing is started at 40 CPM, and the temperature of the fixing roller 91 is maintained only by the commercial power source 86, so that a good copy in the fixing state is possible. At this time, the capacitor 87 is in a standby state. In addition, 60 s is required as a paper passing time. That is, the total copying time is 90 seconds.

As described above, even when the number of continuous paper passes is relatively small and the temperature drop of the fixing roller is slight, if the charging voltage of the capacitor is less than the threshold value, the paper passing speed is lowered and the stored power of the capacitor is reduced. The image was formed without using the printer, and copying took time.
The inventors have found that this problem occurs because the threshold value of the charging voltage is set so as not to cause a temperature drop regardless of the number of continuous sheets to be passed and the type of paper according to the specifications of the copying machine. As a result of careful attention and intensive studies, the present invention has been achieved to solve the above problems by efficiently utilizing capacitors.

  That is, in the third embodiment of the present invention, the overall configuration is basically the same as that in the second embodiment, and a fixing device system similar to the fixing device system 10 shown in FIG. However, there are characteristic differences in the following points.

  The CPU 11 functionally configures the number prediction unit 11a, which is one of core technologies when setting a threshold value for starting charging, and can capture information from the power storage detection unit 18, the image reading unit 1b, and the external input unit 1c. So connected. Further, the CPU 11 takes in the capacitor voltage that is an index of the stored energy (remaining power amount) of the capacitor 17 detected by the power storage detector 18 and the temperature of the fixing roller 91 detected by the temperature sensor 95 as detection signals. .

FIG. 7 shows a block diagram relating to mode selection based on the capacitor voltage in the present invention.
In FIG. 7, the CPU 81 includes a number prediction unit 11 a, a threshold setting unit 11 b, a determination unit 11 c, and a mode selection unit 11 d, which serve as the other core technique when setting a threshold value for starting charging.

  The sheet number predicting unit 11a predicts the total number of sheets that are continuously passed through the fixing device during continuous sheet passing. For example, the total number of sheets may be a value obtained by multiplying the number-of-originals information obtained at the time of image reading from the image reading unit 1a and the number-of-copying information input at the time of a copy command. Further, the total number may be obtained from the number of documents included in the print command information input from the external input unit 1c and the number of printouts.

  Based on the total number information from the sheet number prediction unit 11a, the threshold setting unit 11b is a threshold value related to the capacitor voltage at the time of paper passing (that is, a threshold value for starting charging, and each threshold value described below is a threshold value for starting charging. It has a function to set.

  Specifically, the total number of sheets is divided into a certain range, and a threshold is set for each range, so that the total number information from the number prediction unit 11a is set to the threshold value in the corresponding range. For example, when the total number n is equal to or greater than the conventional threshold value, the threshold value may be a value that is lower than the conventional threshold value when the total number is less than n. Alternatively, first, the sheet passing time t1 when the sheet is continuously fed under the normal CPM condition is calculated from the total sheet number information, and then the capacitor 17 is assumed to supply power to the heaters 94a and 94b from the capacitor 17 during the continuous sheet feeding. The capacitor voltage may be obtained by backward calculation from the capacitor lower limit voltage, which is the lower limit of the dischargeable voltage, by going back by the paper passing time t1, and this value may be used as the threshold value.

  Next, the set threshold information is sent to the determination unit 11c.

  The determination unit 11c has a function of comparing the threshold value set from the threshold value setting unit 11b with the detected capacitor voltage and determining the magnitude thereof.

  The mode selection unit 11d permits or prohibits power supply from the capacitor 17 to the heater 94 at the time of starting the apparatus and during paper feeding operation, and CPM (per minute) according to permission or non-permission of power supply from the capacitor 17 Have multiple modes, such as the number of copies.

In the mode selection unit 11d shown in FIG. 7, the mode selection is performed as follows, for example.
(S31) A continuous copy command is issued by the copy start button.
(S32) The capacitor voltage of the capacitor 17 is detected by the power storage detector 18, and the detection signal is captured by the CPU 11.
(S33) In the sheet number predicting unit 11a, the total number of sheets is obtained by multiplying the number-of-documents information fetched from the image reading unit 1a and the number-of-copying information inputted at the time of the copy command.
(S34) In the threshold setting unit 11b, the predetermined threshold is set as described above, and the information is sent to the determination unit 11c.
(S35) In the determination unit 11c, the detected capacitor voltage is compared with the threshold value set from the threshold value setting unit 11b, the size is determined, and the determination result is sent to the mode selection unit 11d.
(S36) The mode selection unit 11d performs mode selection according to the determination result of step s15, and the operation of the image forming apparatus including the fixing device system is controlled based on the selected mode.

For example, the following modes are prepared as the mode selected in step s36.
(Mode 1) When the detected capacitor voltage is equal to or higher than a preset threshold value, power supply from the capacitor 17 to the heater 94 at the time of passing paper is permitted, and CPM is set as a normal condition.
(Mode 2) When the detected capacitor voltage is less than the set threshold value, power supply from the capacitor 17 to the heater 94 at the time of passing paper is not permitted, and CPM is set as a down condition.

An example of the operation of the fixing device system of this embodiment is shown in FIG. In this case, the preconditions are as follows.
・ Threshold (when continuously passing)
Threshold value A = 30V when the number of continuous sheets passed ≧ 50
When the number of continuous paper passes <50, the threshold B = 25V
-CPM normal conditions: 75 CPM
-CPM down condition: 40 CPM
・ Copy command: 40 sheets continuously passed ・ Capacitor voltage at copy command: 27V

(S41) When a continuous copy command is issued by the copy start button, the capacitor voltage (27V) of the capacitor 17 is detected by the power storage detection unit 18, and the detection signal is captured by the CPU 11.
(S42) In the sheet number predicting unit 11a, the total number of sheets (40 sheets) is obtained by multiplying the number-of-documents information fetched from the image reading unit 1a and the number-of-copying information input at the time of the copy command.
(S43) In the threshold setting unit 11b, a threshold B (threshold for starting charging: 25V) is set based on the total number information (40 sheets) from the number prediction unit 11a, and the information is sent to the determination unit 11c.
(S44) In the determination part 11c, it determines with the detected capacitor voltage (27V) being more than threshold value B (25V), and a determination result is sent to the mode selection part 11d.
(S45) In the mode selection unit 11d, the mode 1 is selected.
(S46) When the apparatus is started up, power supply from the commercial power supply 16 to the heater 94 is started, the fixing roller 91 is heated, and it takes 30 s as a start-up time. At this time, the capacitor 17 is in a standby state.
(S47) Paper feeding is started at 75 CPM, the temperature of the fixing roller 91 is maintained by the power supplied from the commercial power supply 16 and the capacitor 17, and a good copy in the fixing state is possible. In addition, 32 s is required as the paper passing time.

  In the present embodiment, as described above, with the configuration that is the premise of the present invention, it was possible to reduce the total copying time, which took 90 seconds when 40 sheets were continuously copied at 40 CPM, to 62 seconds.

  A configuration example in which the fixing device system 10 according to the present embodiment is incorporated in an image forming apparatus is basically the same as that shown in FIG. 3, and detailed description thereof is omitted. When print command information is input by an external input, the power supply control of the present invention described above is performed. That is, even if the stored energy of the capacitor does not reach the threshold for continuous paper passing, but is higher than the threshold for starting charging set from the number of paper passing predicted based on the input print command information Then, the charge / discharge control unit 11B supplies power from the commercial power supply 16 to the capacitor 17 and proceeds to the charging process. When the stored energy reaches, for example, a threshold for continuous paper passing, the CPU 11 causes the heater 93 of the fixing device to generate heat and starts up the device. Next, the CPU 11 generates heat from the heater 93 of the fixing device, and the charge / discharge control unit 11B constituted by the CPU 11 discharges from the capacitor 17 and also generates heat from the heater 94a or 94b. Heat with efficiency. Thus, it is possible to perform a continuous copy operation under the CPM normal condition.

1 is a circuit diagram of a fixing device system according to a first embodiment of the present invention. FIG. 3 is a block diagram illustrating a functional configuration of a main part of the fixing device system according to the first embodiment. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to a first embodiment. FIG. 9 is a block diagram illustrating a functional configuration of a main part of a fixing device system according to a second embodiment of the present invention. 6 is a time chart illustrating an operation example of a fixing device system according to a second embodiment. 12 is a time chart showing an operation example when the inventive concept is not applied in the fixing device system according to the third embodiment of the present invention. FIG. 10 is a block diagram illustrating a functional configuration of a main part of a fixing device system according to a third embodiment. 12 is a time chart illustrating an operation example of a fixing device system according to a third embodiment. FIG. 3 is an explanatory diagram illustrating a configuration of a fixing device according to the present invention. It is a circuit diagram of a conventional fixing device system. FIG. 10 is a block diagram illustrating a functional configuration of a main part of a conventional fixing device system. 10 is a time chart for explaining the operation of a conventional fixing device system.

Explanation of symbols

1a, 8a Charging device 1b Image reading unit 1c External input unit 10,90 Fixing device system 11 CPU
11A Charge / Discharge Control Unit 11B Charge / Discharge Control Unit 11C Standby Control Unit 11a Number Prediction Unit 11b Threshold Change Unit 11c, 81a Determination Unit 11d, 81b Mode Selection Unit 12, 14, 82, 84 Controller 13, 83 Triac 15, 85 FET
16, 86 Commercial power supply 17, 87 Capacitor 18, 88 Power storage detector 19, 89 Switch 91 Fixing roller 92 Pressure roller 93, 94, 94a, 94b Heater 95 Temperature sensor Csw Copy start switch Ca Control execution unit Dd Information identification unit 100 Image forming apparatus 101 Photoconductor 102 Charging means 103 Cleaning means 105 Developing sleeve 106 Transfer means 107 Developing section 110 Paper feed cassette 111 Middle plate 112 Arm 113 Paper feed roller 114 Separation pad 115 Registration roller pair 120 Paper discharge roller pair 121 Paper discharge port 122 Paper discharge tray 125 Paper discharge auxiliary tray 130 Operation panel 131 Exterior part 132 Paper feed tray 133 Pin 134 Case 135 Power supply circuit 136 Print board 137 Controller board 140 Laser optical system P Over door T toner

Claims (10)

A storage battery that is charged by a commercial power supply; a heater that is heated by being supplied with power from the commercial power supply and the storage battery; a fixing member that is heated by the heater; and a storage battery detection unit that detects the stored energy of the storage battery. In the image forming apparatus in which an unfixed image is heated by the fixing member and fixed on a recording medium.
When starting up to raise the temperature of the fixing member, when the energy stored in the capacitor is equal to or higher than a threshold, a control unit that permits power supply from the capacitor to the heater,
The control unit, when the power storage energy of the battery is less than the threshold at the time of start-up, based on the power storage energy, whether to charge from the commercial power supply to the battery, or to charge An image forming apparatus comprising: selecting an image forming apparatus. A storage battery that is charged by a commercial power supply; a heater that is heated by being supplied with power from the commercial power supply and the storage battery; a fixing member that is heated by the heater; and a storage battery detection unit that detects the stored energy of the storage battery. In the image forming apparatus in which an unfixed image is heated by the fixing member and fixed on a recording medium.
When starting up to raise the temperature of the fixing member, if the stored energy of the battery is equal to or higher than a threshold for starting up, a control unit that permits power supply from the battery to the heater,
If the stored energy of the battery at the time of startup is less than the threshold for startup, the control unit may be configured so that the stored energy is equal to or higher than a threshold for charging permission set lower than the threshold for startup. For example, the image forming apparatus permits charging of the battery from the commercial power source.   The control unit, when the stored energy of the capacitor is less than the threshold for startup and greater than or equal to the threshold for permission of charging, permits the charging from the commercial power source to the capacitor, 3. The image forming apparatus according to claim 1, wherein the recording medium is made to wait until at least the stored energy reaches the threshold for starting up. 4. A storage battery that is charged by a commercial power supply; a heater that is heated by being supplied with power from the commercial power supply and the storage battery; a fixing member that is heated by the heater; and a storage battery detection unit that detects the stored energy of the storage battery. In the image forming apparatus in which an unfixed image is heated by the fixing member and fixed on a recording medium.
A controller that permits power supply from the capacitor to the heater when the energy stored in the capacitor is equal to or greater than a threshold for continuous sheet passing during continuous sheet passing through the fixing member. With
The controller, when the continuous paper is passed, if the energy stored in the battery is less than the threshold for continuous paper passing, either the case where charging from the commercial power supply to the battery is not performed or the case where charging is performed An image forming apparatus.   When the storage energy of the battery is less than the threshold for continuous paper feeding and charging the battery from the commercial power supply, the control unit reaches the threshold for continuous paper feeding. The image forming apparatus according to claim 4, wherein the recording medium is made to wait until the recording medium passes. A sheet number predicting unit for predicting the total number of recording media that pass through the fixing member during the continuous sheet passing;
The control unit charges the capacitor from the commercial power source based on the total number predicted by the sheet number prediction unit when the energy stored in the capacitor is less than the threshold for continuous sheet passing during the continuous sheet passing. 5. The image forming apparatus according to claim 4, wherein the image forming apparatus selects one of a case in which no charging is performed and a case in which charging is performed.   The control unit has a threshold value for starting charging set lower than the threshold value for continuous paper feeding, and compares the stored energy of the capacitor with the threshold value for starting charging, and as a result, the commercial power source 5. The image forming apparatus according to claim 4, wherein one of a case where charging is not performed and a case where charging is performed is selected. A sheet number predicting unit for predicting the total number of recording media that pass through the fixing member during the continuous sheet passing;
8. The image forming apparatus according to claim 7, wherein the threshold value for starting charging is set based on a total number of sheets predicted by the sheet number predicting unit and a sheet passing speed of the recording medium. An image reading unit that reads the image on the document
The image forming apparatus according to claim 6, wherein the number prediction unit predicts the total number based on document reading information of the image reading unit. The image forming apparatus according to claim 6, wherein the number prediction unit predicts the total number based on print command information input from outside.

Images