JP4643363B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus having a fixing unit that fixes toner onto a recording sheet by heat.

  An image forming apparatus such as a copier heats the fixing heater using electric power from a commercial power source, and has an energy saving mode for waiting for a print instruction in a state where power supply to the fixing heater is stopped as an energy saving measure. There is something. In an image forming apparatus having an energy saving mode, the temperature of the fixing heater once the power supply has been stopped falls below a temperature at which fixing can be performed. Therefore, when returning from the energy saving mode to the printing mode, the temperature of the fixing heater is reduced. A waiting time (rise time) until a predetermined temperature is reached is required.

  If a large amount of power is used to return to the print mode, the temperature of the fixing heater can be raised rapidly. However, the commercial power supply in Japan has a maximum of 1500 W at 100 V and 15 A, and the temperature rise time There is a limit to shortening. Therefore, for example, as shown in Patent Document 1 below, in order to shorten the rise time, a chargeable auxiliary power source (capacitor or battery) is provided, and in the energy saving mode, the auxiliary power source is charged by a commercial power source. An image forming apparatus that shortens the rise time by flowing a large current to the fixing heater using both a commercial power supply and an auxiliary power supply when returning to the print mode has been proposed.

  Here, the characteristics of the electric double layer capacitor suitable for the capacitor as the auxiliary power source and the lithium ion battery suitable for the battery as the auxiliary power source will be described. The electric double layer capacitor is characterized in that it can be charged / discharged with a large current and has a relatively long charge / discharge life (for example, on the order of several hundred thousand times), but the voltage drops rapidly. Therefore, in order to supply power for a long time, it is necessary to increase the capacity, which is expensive.

A lithium ion battery has a feature that a decrease in voltage until the end of discharge is small. Therefore, it is possible to supply electric power for a long time at a lower cost compared with the electric double layer capacitor. Moreover, a lithium ion battery has the property that a lifetime becomes short, so that charging / discharging is repeated with a large electric current. When the halogen heater used for the fixing heater is lit from a state cooled to about room temperature, a large inrush current flows to the halogen heater and a current nearly 10 times the rated current may flow. In the case where it is carried out, the life of the repeated number of times of charging and discharging of the lithium ion battery is relatively short, about 500 to 1000 times.
Japanese Patent Laid-Open No. 10-282821

  However, when a large current flows from both the external power supply and the auxiliary power supply to the fixing heater when returning from the energy saving mode to the printing mode as described above, if an electric double layer capacitor is used as the auxiliary power supply, the electric double layer capacitor is Since the voltage rapidly decreases from the start of discharge, it is necessary to increase the capacity to enable long-term use, and the electric double layer capacitor becomes expensive. In addition, the halogen heater used in the fixing roller generates a large current when it is lit from a cold temperature of about room temperature. Therefore, when a lithium ion battery is used as an auxiliary power source, charging and discharging must be repeated with a large current. The life of the lithium ion battery is shortened.

  The present invention has been made in view of the above problems, and provides an image forming apparatus that has a long life of an auxiliary power source and is inexpensive while reducing the time required to raise the temperature of the fixing unit to a fixable temperature. With the goal.

The invention according to claim 1 is a first auxiliary power source comprising a capacitor;
A second auxiliary power source comprising a secondary battery, wherein the output voltage at full charge is lower than the output voltage at full charge of the first auxiliary power source;
A first fixing heater that heats a fixing unit that fixes toner onto a recording sheet with electric power from the first auxiliary power supply;
A second fixing heater comprising a halogen heater and heating the fixing unit with any of the electric power from the first or second auxiliary power source;
A third fixing heater for heating the fixing unit with electric power from an external power source;
A power supply selection means for selectively supplying power from the higher one of the first or second auxiliary power supplies to the second fixing heater;
When the second fixing heater is driven and the second fixing heater reaches a rated current value, the output voltage of the first auxiliary power supply is set to be lower than the output voltage of the second auxiliary power supply. An image forming apparatus.

  In this configuration, the output voltage of the second auxiliary power supply is lower than the output voltage at the time of full charge of the first auxiliary power supply immediately after the start of the driving of the second fixing heater composed of the halogen heater. Power from one auxiliary power source is supplied to the second fixing heater. When the second fixing heater settles to the rated current value after the driving of the second fixing heater is started, the output voltage of the first auxiliary power supply becomes lower than the output voltage of the second auxiliary power supply at this time, so that power supply is performed. Electric power from the second auxiliary power source is supplied to the second fixing heater by the selection means.

  A second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the power supply selection unit includes a first diode provided between the first auxiliary power source and the second fixing heater. And a second diode provided between the second auxiliary power source and the second fixing heater and connected in parallel with the first diode.

  In this configuration, since the power supply selection means includes the first and second diodes, the power from the higher output voltage of the first or second auxiliary power source is selected without performing special control. To the second fixing heater.

The invention according to claim 3 is the image forming apparatus according to claim 1 or 2, wherein the power of the first auxiliary power supply is discharged and supplied to the first and second fixing heaters. First charge / discharge switching means for switching whether to charge the first auxiliary power with power from an external power source;
Second charge / discharge switching means for switching whether to discharge the power of the second auxiliary power source and supply it to the second fixing heater, or to charge the second auxiliary power source with power from the external power source;
Third fixing heater driving means for switching whether to drive the third fixing heater with electric power from the external power source;
State determining means for determining whether the main power switch of the image forming apparatus is in an on state or an off state;
When the main power switch is determined to be in the ON state by the state determination unit, the first and second charge / discharge switching units are switched to the discharge side, and the third fixing heater driving unit performs the third fixing. When the heater is driven and the main power switch is determined to be off by the state determination means, the first and second charge / discharge switching means are switched to the charge side and the third fixing heater drive means And a control means for stopping the third fixing heater.

  In this configuration, when the state determination unit determines that the main power switch of the image forming apparatus is in the ON state, the control unit causes the first charge / discharge switching unit to discharge the first auxiliary power. Switching to the side supplied toward the first and second fixing heaters, switching the second charge / discharge switching means to the side where the power of the second auxiliary power source is discharged and supplied toward the second fixing heater, By driving the third fixing heater by the third fixing heater driving means, a current is supplied to the first to third fixing heaters by external power and the power from the first or second auxiliary power source, and the fixing unit is operated for a short time. Increase the temperature with. On the other hand, when the state determining unit determines that the main power switch of the image forming apparatus is in the OFF state, the control unit stops the third fixing heater by the third fixing heater driving unit, and The second charging / discharging switching means is switched so that the first and second auxiliary power supplies are charged with power from the external power supply.

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the state discriminating unit drives the first and second fixing heaters when the main power switch is on. It is further determined whether the heater is on or whether the first and second fixing heaters are stopped.
The control means sets the first and second charge / discharge switching means only when the main power switch is determined to be in the ON state by the state determination means and only when the heater is determined to be in the ON state. When switching to the discharge side and determining that the heater is off, the first and second charge / discharge switching means are switched to the charge side.

  In this configuration, even when the main power switch is in the on state, the control means is connected to the external power only when the state determination means determines that the heaters are in the heater on state where the first and second fixing heaters are driven. A current is supplied to the first to third fixing heaters with electric power from the first or second auxiliary power source so that the temperature of the fixing unit rises in a short time. If it is determined that the heater is turned off, it is not necessary to supply power from the first and second auxiliary power supplies to the first and second fixing heaters, so the first and second charge / discharge switching means are switched, The first and second auxiliary power supplies are charged with power from the external power supply.

  According to the first aspect of the present invention, since the first and second fixing heaters are heated by the electric power from the first and second auxiliary power supplies in addition to the third fixing heater, the temperature of the fixing unit can be fixed. The waiting time (rise time) until the temperature is reached can be shortened. As a result, the heaters of the fixing unit can be turned off at the time of printing standby, so that significant power saving can be achieved. Further, even when the temperature of the fixing unit is lowered due to paper passing during the fixing operation, the first and second fixing heaters can perform heating to compensate for the temperature decrease.

  In addition, when the second fixing heater made of a halogen heater is turned on in a cooled state, a large inrush current that greatly exceeds the rated current flows at the start of lighting, but the power to the second fixing heater at this time The supply is performed from the first auxiliary power source composed of a capacitor, and after the second fixing heater reaches the rated current value, the power is switched to be supplied from the second auxiliary power source composed of the secondary battery. The current supplied from the second auxiliary power source to the second fixing heater is always the rated current, and charging / discharging is not repeated with a large current, so that the life of the secondary battery can be kept long. Further, when the first auxiliary power source composed of a capacitor releases electric charges and the voltage decreases, the power supply is switched from the second auxiliary power source, and stable power supply is performed from the second auxiliary power source. Stable power supply to the heater can be continued from the start of driving the second fixing heater.

  According to the second aspect of the present invention, the power from the higher output voltage of the first or second auxiliary power supply can be supplied to the second fixing heater without performing special control.

  According to the third aspect of the present invention, when the main power switch of the image forming apparatus is in the ON state, the first to third fixing heaters are largely powered by the external power and the power from the first or second auxiliary power. While the temperature of the fixing unit is raised in a short time by supplying an electric current, when the main power switch is in the OFF state, the first and second auxiliary power sources are charged with power from the external power source to heat the fixing unit. The first and second auxiliary power supplies can be charged at a timing that does not cause a problem.

  According to the fourth aspect of the present invention, even when the main power switch is in the on state, when the first and second fixing heaters are in the heater off state, the first power is supplied from the external power source. And the second auxiliary power supply is charged, and even when the main power switch is turned on, the timing at which the heating of the fixing unit is not hindered is detected, and the first and second auxiliary power supplies are appropriately charged. can do.

  Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an internal configuration of a multi-function peripheral which is an embodiment of an image forming apparatus according to the present invention. In particular, a fixing heater control mechanism for controlling on / off of a fixing heater for heating a fixing roller is mainly shown. FIG. FIG. 2 shows each state type of the multifunction device 1 (plug-in state, initial startup state, print state, ready state, sleep state, and rapid startup state) and an opportunity to transition from each state to another state. This is state transition information indicating the type of event. Note that the image forming apparatus according to the present invention may be, for example, a printer, a copier, a facsimile machine, or the above-described multifunction machine having these functions. In this embodiment, an image forming apparatus according to the present invention will be described by taking a multifunction peripheral as an example. In the multifunction machine 1, the fixing roller (not shown) is a toner image transferred from a photosensitive drum onto a recording sheet by niping the toner image with a heat roller and a pressure roller (not shown). Is fixed on the recording paper.

  The external power source 2 is a so-called commercial power source, for example, and is an AC (alternating current) power source by an electric power company. The power supply control circuit 9 controls whether or not the power from the external power supply 2 is supplied to each part of the apparatus in response to turning on or off of the main switch 10 that is a main power switch for starting the multifunction machine 1. .

  The multifunction device 1 includes an image forming unit 11, an instruction receiving unit 12, a timer 13, a fixing roller temperature sensor 14, a control unit 15, a first fixing heater 17, an electric double layer capacitor 18, a capacitor charge / discharge changeover switch 19, and a capacitor charge control. The circuit 20 includes a second fixing heater 21, a power supply selection unit 22, a lithium ion battery 23, a battery charge / discharge switch 24, a battery charge control circuit 25, a third fixing heater 26, and a third fixing heater drive circuit 27.

  The image forming unit 11 performs image formation for forming a toner image on recording paper. The multifunction device 1 operates in response to a print instruction when, for example, a copy function, a printer function, or a facsimile reception function is executed. . The instruction receiving unit 12 receives various operation execution instructions from the user or the like with respect to the multifunction machine 1, and receives, for example, execution instructions for a copy function, a printer function, and a facsimile reception function. In the instruction receiving unit 12, a copy function execution instruction is input to the multifunction device 1 by the user from the operation panel (not shown) of the multifunction device 1. The printer function execution instruction is transmitted to the multifunction device 1 from, for example, a PC (personal computer) connected to the multifunction device 1 via a network or the like. The facsimile reception execution instruction is transmitted to the multifunction device 1 from a facsimile transmission device connected to the multifunction device 1 through a public line or the like.

  The timer 13 measures the elapsed time from the time when the instruction is received from the state determination unit 152. The fixing roller temperature sensor 14 measures the temperature of the fixing roller and outputs it to the fixing roller temperature control unit 151 and the like.

  The first fixing heater 17, the second fixing heater 21, and the third fixing heater 26 are heaters for heating the fixing roller, and in the present embodiment, are composed of halogen heaters. The first fixing heater 17 is, for example, a 1300 W DC (direct current) heater. The second fixing heater 21 is a DC heater of 500 W, for example. The third fixing heater 26 is, for example, a 1200 W AC (alternating current) heater. The first fixing heater 17 uses a large power consumption in order to heat rapidly by flowing a large current. The first fixing heater 17, the second fixing heater 21, and the third fixing heater 26 are installed adjacent to each other.

  The electric double layer capacitor (first auxiliary power source) 18 functions as a power source for driving the first fixing heater 17. The electric double layer capacitor 18 can be charged and discharged with a large current. The electric double layer capacitor 18 has a characteristic that the charge / discharge repetition life is relatively long (for example, on the order of several hundred thousand times), but the electric power (voltage) rapidly decreases when the electric charge is discharged. The charging time of the electric double layer capacitor 18 is several tens of seconds, for example. The electric double layer capacitor 18 also functions as a power source for driving the second fixing heater 21 via the power supply selection unit 22 as will be described later.

  The capacitor charge / discharge changeover switch 19 (first charge / discharge changeover means) either (1) discharges the electric double layer capacitor 18 and drives the first fixing heater 17 using the electric double layer capacitor 18 as a power supply source, or (2 This is a switch for switching whether to charge the electric double layer capacitor 18 using the external power source 2 as a power supply source. When the switch is switched to the charge side, the electric double layer capacitor 18 is charged, and when the switch is switched to the discharge side, the first fixing heater 17 is driven.

  The capacitor charge control circuit 20 (first charge / discharge switching means) determines whether or not to charge the electric double layer capacitor 18 by switching whether or not the electric power from the external power source 2 is supplied to the electric double layer capacitor 18. Switch to switch. That is, the capacitor charge / discharge changeover switch 19 is switched to the side where the electric double layer capacitor 18 is charged, and the capacitor charge control circuit 20 supplies the electric double layer capacitor 18 with the electric power from the external power source 2. The double layer capacitor 18 is charged.

  The lithium ion battery (secondary battery, second auxiliary power source) 23 is a rechargeable power source that functions as a power source for driving the second fixing heater 21. The lithium ion battery 23 is characterized by a small voltage drop until the end of discharge. The charging time of the lithium ion battery 23 is, for example, 10 minutes.

  The battery charge / discharge changeover switch (second charge / discharge changeover means) 24 is either (1) connected to a circuit to discharge the lithium ion battery 23 and drive the second fixing heater 21 or (2) the external power supply 2 Is a switch for switching whether to connect the circuit so that the lithium ion battery 23 is charged.

  The battery charge control circuit (second charge / discharge switching means) 25 switches whether to charge the lithium ion battery 23 by switching whether to supply power from the external power source 2 to the lithium ion battery 23. It is. That is, the battery charge / discharge switch 24 is switched to the side for charging the lithium ion battery 23, and the battery charge control circuit 25 supplies the power from the external power source 2 to the lithium ion battery 23. Is charged.

  The power supply selection unit (power supply selection means) 22 includes a first diode provided between the electric double layer capacitor 18 and the second fixing heater 21, and a lithium ion battery and the second fixing heater. And a second diode provided. As shown in FIG. 4 to be described later, these first and second diodes are connected in parallel, and the electric power from the higher output voltage of the electric double layer capacitor 18 or the lithium ion battery 23 is selectively second. The fixing heater 21 is supplied.

  The third fixing heater driving circuit (third fixing heater driving means) 27 determines whether to drive the third fixing heater 26 using the external power source 2 as a power supply source, that is, whether to heat the third fixing heater 26. It functions as a switch to switch between. When the third fixing heater driving circuit 27 is turned on, the third fixing heater 26 is driven, and when the switch is turned off, the third fixing heater 26 is stopped.

  The control unit 15 controls the overall operation of the multifunction machine 1, and includes a CPU (Central Processing Unit) that executes a program, a ROM (Read Only Memory) that stores the program, and a temporary storage area when the program is executed. It is comprised from RAM (random access memory) etc. which are used as. The control unit 15 includes a fixing roller temperature control unit 151, a state determination unit 152, and a switch control unit 153.

  The state determination unit (state determination unit) 152 determines whether the current state of the MFP 1 is in an initial startup state, a print state, a ready state, a sleep state, a plug-in state, or a rapid startup state. It is to be determined. The state determination unit 152 determines whether the multifunction device 1 is in any one of the above states based on the on / off state of the main switch 10 sent from the power supply control circuit 9 or the absence of a print instruction from the instruction receiving unit 12 for a predetermined time. Determine if it is in a state.

  The initial start-up state is a predetermined first temperature range (for example, 180 ° C.) in which the temperature of the fixing roller can be fixed from the time when the power is turned on to the multifunction device 1 (after the main switch 10 is turned on). It is a state up to.

  The print state is a state while the multifunction device 1 is performing a printing operation (a state from when printing (including copying) is completed until it is completed). In the printing state, the temperature of the fixing roller is kept within the first temperature range.

  The ready state is a state where the input of the print instruction is waited and the fixing roller can be immediately raised to the first temperature range if there is a print instruction. In this ready state, the temperature of the fixing roller is set to a second temperature range (for example, 90 ° C.) that is lower than the first temperature range.

  The sleep state is a state in which the first fixing heater 17, the second fixing heater 21, and the third fixing heater 26 are turned off in order to save power. When the print instruction is not input for a certain period of time, the sleep state starts from the ready state. Transition to sleep mode.

  The plug-in state is a state where the power plug is inserted into the outlet of the external power source 2 but the main switch 10 is turned off.

  The rapid start-up state refers to a state in which, when a print instruction is received in the sleep state, the temperature of the fixing roller rises to the first temperature range in which the fixing roller can be fixed.

  The state determination unit 152 stores the state transition information shown in FIG. 2 in advance, and determines the current state (transition source state) and the state (transition destination state) that makes the next transition from the generated event. The state determination unit 152 sends information indicating the determined current state and the next transition state to the switch control unit 153.

  The fixing roller temperature control unit 151 obtains the temperature of the fixing roller from the fixing roller temperature sensor 14, and when the multifunction device 1 is in a printing state, the upper limit of the first temperature range in which the fixing roller temperature can be fixed. Until the battery charging / discharging switch 24 is switched to the discharging side (the side supplying power to the second fixing heater 21) until the fixing roller temperature reaches the upper limit of the first temperature range. The battery charging / discharging changeover switch 24 is repeatedly switched to the charging side (the side that charges the lithium ion battery 23 with power from the external power supply 2) until the lower limit of the first temperature range is reached. Keep within the temperature range of.

  The switch control unit (control unit) 153 is configured to switch the capacitor charge / discharge switch 19 for each current state of the multifunction machine 1 determined by the state determination unit 152 or based on an instruction from the fixing roller temperature control unit 151. The capacitor charge control circuit 20, the battery charge / discharge switch 24, the battery charge control circuit 25, and the third fixing heater drive circuit 27 are controlled.

  FIG. 3 is a diagram showing states of the capacitor charge / discharge changeover switch 19, the capacitor charge control circuit 20, the battery charge / discharge changeover switch 24, the battery charge control circuit 25, and the third fixing heater drive circuit 27 in each state of the multifunction machine 1. It is. The states of the capacitor charge / discharge changeover switch 19, the capacitor charge control circuit 20, the battery charge / discharge changeover switch 24, the battery charge control circuit 25, and the third fixing heater drive circuit 27 corresponding to each state of the multi-function device 1 are the switch control unit. 153 may be stored by itself, or may be stored in a storage unit (not shown) and read by the switch control unit 153 as necessary. Further, in the power supply control by the capacitor charge control circuit 20 and the battery charge control circuit 25, the case where power is supplied is shown as ON, and the case where power is not supplied is shown as OFF.

  In the initial start-up state and the quick start-up state, the capacitor charge / discharge switch 19 is switched to the side that discharges the electric double layer capacitor 18 (the side that supplies power to the first fixing heater 17 or the second fixing heater 21). The capacitor charge control circuit 20 is turned off. Further, the battery charge / discharge switch 24 is switched to the side for discharging the lithium ion battery 23 (the side for supplying power to the second fixing heater 21), and the battery charge control circuit 25 is turned off. Further, the third fixing heater driving circuit 27 is turned on and the third fixing heater 26 is driven.

  In the ready state, the capacitor charging / discharging changeover switch 19 is switched to the side for charging the electric double layer capacitor 18 with the electric power from the external power supply 2, and the capacitor charging control circuit 20 is turned on. Further, the battery charge / discharge changeover switch 24 is switched to the side for charging the lithium ion battery 23 with the electric power from the external power supply 2, and the battery charge control circuit 25 is turned on. Further, the third fixing heater driving circuit 27 is turned on, and the third fixing heater 26 is maintained in the driven state.

  In the sleep state and the plug-in state, the capacitor charge / discharge switch 19 is set to charge the electric double layer capacitor 18 with power from the external power supply 2, and the capacitor charge control circuit 20 is turned on. The battery charge / discharge changeover switch 24 is on the side for charging the lithium ion battery 23 with the electric power from the external power supply 2, and the battery charge control circuit 25 is turned on. The third fixing heater drive circuit 27 is turned off, and the third fixing heater 26 is stopped.

  In the printing state, in order to keep the temperature of the fixing roller within the first temperature range in which the fixing roller can be fixed, the battery charge / discharge switch 24 is switched from the fixing roller temperature sensor 14 to the charge side or the discharge side. This is performed in a timely manner according to the fixing roller temperature. The battery charge control circuit 25 is turned off. The capacitor charging / discharging changeover switch 19 is a side for charging the electric double layer capacitor 18 with electric power from the external power source 2, and the capacitor charging control circuit 20 is turned on. On the other hand, the third fixing heater driving circuit 27 is turned on, and the third fixing heater 26 is maintained in the driven state.

  Next, a circuit image of the multifunction device 1 fixing heater control mechanism according to the present invention will be described. FIG. 4 is a circuit diagram showing a circuit image (outline) of the fixing heater control mechanism.

  The external power source (AC) 2 is connected to the third fixing heater 26 via the third fixing heater driving circuit 27. The external power source 2 is connected to the first fixing heater 17 and the second fixing heater 21 via a diode 41 that rectifies AC current into DC current. As a result, a DC current flows through the first fixing heater 17 and the second fixing heater 21, and an AC current flows through the third fixing heater 26. The first fixing heater 17, the second fixing heater 21 and the third fixing heater 26 constitute a fixing heater 30.

  The circuit on the third fixing heater 26 side includes an external power source 2 and a third fixing heater 26, and a third fixing heater drive circuit 27 is connected between the external power source 2 and the second fixing heater 21. Yes. The second fixing heater driving circuit 27 can control whether or not the third fixing heater 26 is driven by the electric power from the external power source 2.

  The circuit to which the first fixing heater 17 is connected includes a capacitor charge control circuit 20, a capacitor charge / discharge switch 19, and an electric double layer capacitor 18. Whether or not the current from the diode 41 is supplied to the electric double layer capacitor 18 by the capacitor charge control circuit 20 is controlled. The capacitor charge / discharge changeover switch 19 is provided between the capacitor charge control circuit 20 and the electric double layer capacitor 18, and (1) the electric double layer capacitor 18 is connected to the capacitor charge control circuit by the capacitor charge / discharge changeover switch 19. Or connected to the side 20 and charged by the electric power from the external power source 2, or (2) the electric double layer capacitor 18 is connected to the first fixing heater 17 side to be discharged and the electric double layer capacitor 18 is discharged. The connection to drive the first fixing heater 17 with the power from is switched.

  The circuit to which the second fixing heater 21 is connected includes a battery charge control circuit 25, a battery charge / discharge switch 24, and a lithium ion battery 23. Whether or not the current from the diode 41 is supplied to the lithium ion battery 23 by the battery charge control circuit 25 is controlled. The battery charge / discharge changeover switch 24 is provided between the battery charge control circuit 25 and the lithium ion battery 23, and (1) the lithium ion battery 23 is connected to the battery charge control circuit 25 side by the battery charge / discharge changeover switch 24. Or connected to the external power source 2 and charged with power from the external power source 2 or (2) connecting the lithium ion battery 23 to the second fixing heater 21 side and discharging it, and using the power from the lithium ion battery 23 to 2 The connection to drive the fixing heater 21 is switched.

  Further, the connection between the electric double layer capacitor 18 and the second fixing heater 21 and the connection between the lithium ion battery 23 and the second fixing heater 21 are performed via the power supply selection unit 22. As shown in FIG. 4, the power supply selection unit 22 includes a first diode 221 provided between the electric double layer capacitor 18 and the second fixing heater 21, a lithium ion battery 23, and the second fixing heater 21. And a second diode 222 provided in between and connected in parallel to the first diode 221. According to the power supply selection unit 22 having this configuration, only the current from the higher output voltage of the electric double layer capacitor 18 or the lithium ion battery 23 flows to the second fixing heater 21 due to the nature of the diode. When the capacitor charge / discharge changeover switch 19 and the battery charge / discharge changeover switch 24 are switched to the discharge side, the electric power from the higher output voltage of the electric double layer capacitor 18 or the lithium ion battery 23 is selected at that time. It is supplied to the second fixing heater 21.

  FIG. 5 is a graph showing the relationship between the output voltage of the electric double layer capacitor 18 and the lithium ion battery 23 and the current flowing through the second fixing heater 21. FIG. 6A is a diagram showing power supply to the fixing heater 30 at the initial start-up time of the second fixing heater 21, and FIG. 6B is a fixing heater at a time when the second fixing heater 21 settles to the rated current value after starting driving. 3 is a diagram showing power supply to 30. FIG.

  As shown in FIG. 5, the lithium ion battery 23 is set so that the output voltage when fully charged is lower than the output voltage when fully charging the electric double layer capacitor 18, and the second fixing heater 21 is driven. The output voltage of the electric double layer capacitor 18 is set to be lower than the output voltage of the lithium ion battery 23 at the time when the electric current reaches the rated current value. For example, at the time 0.5 seconds after the start of driving of the second fixing heater 21, the second fixing heater 21 has not yet settled to the rated current value, the resistance of the second fixing heater 21 is 3Ω, and the second fixing heater 21. In this case, the output voltage of the lithium ion battery 23 is set to 40V, and the output voltage of the electric double layer capacitor 18 is set to 42V. The second fixing heater 21 settles to the rated current value (for example, after 1 second from the start of driving of the second fixing heater 21), the resistance of the second fixing heater 21 is 4Ω, and the current flowing through the second fixing heater 21 is 8A. When the voltage settles down, the output voltage of the lithium ion battery 23 is set to 40V, and the output voltage of the electric double layer capacitor 18 is set to be lower than 40V.

  Thereby, from the start of driving of the second fixing heater 21 until the second fixing heater 21 settles to the rated current value, as shown in FIG. 6A, the current from the electric double layer capacitor 18 is changed to the power supply selection unit 22. From the time when the second fixing heater 21 settles to the rated current value as shown in FIG. 6B, the current from the lithium ion battery 23 is supplied with the power supply selection unit. 22 is selected and flows to the second fixing heater 21. In the initial startup state and the rapid startup state in which the second fixing heater 21 is driven, since the first fixing heater 17 and the third fixing heater 26 are also driven, as shown in FIGS. In addition, a current from the electric double layer capacitor 18 is supplied to the first fixing heater 17, and a current from the external power source 2 is supplied to the third fixing heater 26.

  Next, processing during fixing heater driving control in the multifunction machine 1 will be described. 7 and 8 are flowcharts showing processing during fixing heater drive control in the multi-function device 1.

  When the power plug of the multifunction device 1 is attached to the outlet and a signal indicating the state is sent from the power control circuit 9 to the state determination unit 152, the state determination unit 152 indicates that the state of the multifunction device 1 is in the plug-in state. It is determined that it has become. If it discriminate | determines in this way, the switch control part 153 will switch the capacitor charging / discharging changeover switch 19 to the side by which the electric double layer capacitor 18 is charged with the electric power from the external power supply 2, and the capacitor charging control circuit 20 (2) The battery charge / discharge switch 24 is switched to the side where the lithium ion battery 23 is charged by the electric power from the external power source 2, the battery charge control circuit 25 is turned on, and (3) the third fixing heater is driven. The circuit 27 is turned off, and the third fixing heater 26 is stopped (S1). Thereby, charging of the electric double layer capacitor 18 and the lithium ion battery 23 is started by the power from the external power source 2.

  When the power control circuit 9 detects that the main switch (power switch) 10 of the multi-function device 1 is turned on (YES in S2), the power control circuit 9 confirms that the main switch 10 is turned on. The signal shown is sent to the state determination unit 152. When the state determination unit 152 determines that the state of the multifunction device 1 is the initial startup state and sends a signal indicating the device state to the switch control unit 153, the state control unit 152 (1) The capacitor charging / discharging changeover switch 19 is switched to the side for discharging the electric double layer capacitor 18 (the side for supplying power to the first fixing heater 17), the capacitor charging control circuit 20 is turned off, and (2) the battery charging The discharge changeover switch 24 is switched to the side that discharges the lithium ion battery 23 (the side that supplies power to the second fixing heater 21), the battery charge control circuit 25 is turned off, and (3) the third fixing heater drive circuit 27 is The third fixing heater 26 is driven to turn on (S3). When the switching control is performed as described above, if the electric double layer capacitor 18 and the lithium ion battery 23 are charged (only the electric double layer capacitor 18 needs to be charged in the initial stage of startup), the third fixing heater. In addition to 26, the first fixing heater 17 and the second fixing heater 21 are also driven. In addition, when the second fixing heater 21 is driven, in the initial startup stage, the power supply selection unit 22 selects and supplies power from the electric double layer capacitor 18 to the second fixing heater 21. This state continues until it is detected by the fixing roller temperature control unit 151 and the switch control unit 153 that the temperature of the fixing roller obtained from the fixing roller temperature sensor 14 has reached the first temperature range described above ( NO in S4).

  When the temperature of the fixing roller reaches the first temperature range (YES in S4), the state determination unit 152 determines whether a signal indicating that a print instruction has been received from the instruction reception unit 12 has been input (S5). When a signal indicating that a print instruction has been received is input from the instruction reception unit 12 (YES in S5), the state determination unit 152 determines that the state of the multifunction device 1 is the print state, and indicates this apparatus state. A signal is sent to the switch control unit 153. The switch control unit 153 (1) maintains the state where the third fixing heater drive circuit 27 is turned on and the third fixing heater 26 is driven, and (2) the capacitor charge / discharge switch 19 is switched to the electric double layer capacitor 18. The capacitor charging control circuit 20 is turned on by switching to the side charged with the power from the external power source 2, but (3) the battery charging / discharging switch 24 is set so that the temperature of the fixing roller is kept within the first temperature range. In addition, the connection to the charge side / discharge side is switched in a timely manner according to the fixing roller temperature sensor 14, and the battery charge control circuit 25 is turned off (S6). At the time of printing, depending on the sheet passing condition to the fixing roller, the heating of the fixing roller may be taken away by the recording paper only by the heating by the third fixing heater 26, so that the temperature of the fixing roller is reduced. This is to keep the temperature of the fixing roller constant. At this time, as described above, the power from the lithium ion battery 23 is supplied to the second fixing heater 21 from the time when the second fixing heater 21 settles to the rated current value.

  When printing is completed (YES in S7), the state determination unit 152 determines that the state of the multifunction device 1 is in the ready state, and sends a signal indicating the device state to the switch control unit 153. The switch control unit 153 switches (1) the capacitor charge / discharge switch 19 to the side that charges the electric double layer capacitor 18, turns on the capacitor charge control circuit 20, and (2) switches the battery charge / discharge switch 24 to the lithium Switching to the side to charge the ion battery 23, the battery charging control circuit 25 is turned on, and (3) the third fixing heater driving circuit 27 is turned on, and the state where the third fixing heater 26 is driven is maintained (S8).

  Even when the signal indicating that the print instruction is received from the instruction receiving unit 12 in S5 is not input to the state determining unit 152 (NO in S5), the state determining unit 152 sets the state of the multifunction device 1 to the ready state. When it is determined that the device status has been reached, this device status is sent to the switch control unit 153, and the process of S8 is performed.

  When the state determination unit 152 determines that the state of the multifunction device 1 is the ready state, the state determination unit 152 performs the processing of S8 and measures the time elapsed from the time when the state of the multifunction device 1 is determined as the ready state. Start (S9). If a signal indicating that a print instruction has been received is input from the instruction receiving unit 12 to the state determining unit 152 during the elapsed time measurement by the timer 13 (YES in S10), the state determining unit 152 The state of 1 is determined as the print state, and the process of S6 is performed again.

  If it is measured by the timer 13 that a predetermined time (for example, 1 minute) has elapsed without receiving a print instruction (NO in S10) (YES in S11), the state determination unit 152 determines that the multifunction device 1 It is determined that the state is the sleep state, and a signal indicating the device state is sent to the switch control unit 153. The switch control unit 153 switches (1) the capacitor charge / discharge switch 19 to the side that charges the electric double layer capacitor 18, turns on the capacitor charge control circuit 20, and (2) switches the battery charge / discharge switch 24 to the lithium Switching to the side for charging the ion battery 23, the battery charge control circuit 25 is turned on, and (3) the third fixing heater drive circuit 27 is turned off and the third fixing heater 26 is stopped (S12). In this way, all of the first fixing heater 17, the second fixing heater 21 and the third fixing heater 26 are stopped, and the printer waits for a further print instruction in a state where power consumption is reduced.

  When a signal indicating that a print instruction has been received from the instruction receiving unit 12 is input to the state determining unit 152 in the sleep state (YES in S13), the state determining unit 152 indicates that the state of the multifunction device 1 is It is determined that a rapid start-up state has been reached, and a signal indicating this device state is sent to the switch control unit 153. In the case of the rapid start-up state, the process returns to S3, and the switch control unit 153 (1) causes the capacitor charge / discharge switch 19 to discharge the electric double layer capacitor 18 (the first fixing heater 17 and the second fixing heater). The capacitor charge control circuit 20 is turned off, and (2) the battery charge / discharge switch 24 is supplied to the side that discharges the lithium ion battery 23 (power is supplied to the second fixing heater 21). The battery charging control circuit 25 is turned off, and the third fixing heater driving circuit 27 is turned on to drive the third fixing heater 26. Thereafter, the processes from S3 to S13 are repeated.

  If it is detected that the main switch 10 is turned off at any point in time of the processes from S3 to S13, the process returns to S1.

  In addition, this invention is not limited to the thing of the said embodiment, The aspect described below can be employ | adopted further. For example, in the above-described embodiment, the power supply selection unit 22 is described as including the first diode 221 and the second diode 222. However, the power supply selection unit 22 includes the first diode 221 and the second diode. It is not restricted to what consists of 222, From the other structure, if the electric double layer capacitor 18 or the lithium ion battery 23 can selectively supply the electric power from the higher output voltage to the second fixing heater 21 It does not matter.

  In the above embodiment, the battery charge control circuit 25 is turned off in the print state. However, the battery charge control circuit 25 may be turned on. In this case, the lithium ion battery 23 can be charged frequently.

  In the above embodiment, a DC current flows through the first fixing heater 17 and the second fixing heater 21 and an AC current flows through the third fixing heater 26. It is not limited to whether AC or DC is used for the current passed through the fixing heater.

  In each of the above embodiments, the electric double layer capacitor 18 is used as an auxiliary power source and the lithium ion battery 23 is used as a secondary battery. However, the electric double layer capacitor 18 or the lithium ion battery 23 is an auxiliary power source or a secondary battery. It is only an example of a battery and you may use another as an auxiliary power supply or a secondary battery.

  Further, the configuration and processing shown in FIGS. 1 to 8 are merely one embodiment of the present invention, and the configuration and processing of the present invention are not limited to these.

1 is a block diagram illustrating an internal configuration of a multifunction peripheral that is an embodiment of an image forming apparatus according to the present invention, and particularly a functional configuration centering on a fixing heater control mechanism that controls on / off of a fixing heater that heats a fixing roller; FIG. Each status type of the MFP (initial startup status, print status, ready status, sleep status, plug-in status, and rapid startup status) and the event type that triggers transition from each status to another status State transition information to be shown. It is a figure which shows the state of the capacitor charging / discharging switch, the capacitor charging control circuit, the battery charging / discharging switching switch, the battery charging control circuit, and the third fixing heater driving circuit in each state of the multifunction machine. It is a circuit diagram which shows the circuit image (outline) of a fixing heater control mechanism. It is the figure which represented the relationship between the output voltage of an electric double layer capacitor and a lithium ion battery, and the electric current which flows into a 2nd fixing heater with a graph. (A) is a diagram showing the power supply to the fixing heater in the initial stage of the start-up of the second fixing heater, (b) the power supply to the fixing heater at the time when the second fixing heater has settled to the rated current value after the start of driving. FIG. 6 is a flowchart showing processing during driving of the fixing heater in the multifunction machine. 6 is a flowchart showing processing during driving of the fixing heater in the multifunction machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multifunction machine 2 External power supply 9 Power supply control circuit 10 Main switch 15 Control part 153 Switch control part 17 1st fixing heater 18 Electric double layer capacitor 19 Capacitor charge / discharge switching switch 20 Capacitor charge control circuit 21 2nd fixing heater 22 Power supply selection Unit 221 First diode 222 Second diode 23 Lithium ion battery 24 Battery charge / discharge switch 25 Battery charge control circuit 26 Third fixing heater 27 Third fixing heater drive circuit 30 Fixing heater

Claims (4)

A first auxiliary power source comprising a capacitor;
A second auxiliary power source comprising a secondary battery, wherein the output voltage at full charge is lower than the output voltage at full charge of the first auxiliary power source;
A first fixing heater that heats a fixing unit that fixes toner onto a recording sheet with electric power from the first auxiliary power supply;
A second fixing heater comprising a halogen heater and heating the fixing unit with any of the electric power from the first or second auxiliary power source;
A third fixing heater for heating the fixing unit with electric power from an external power source;
A power supply selection means for selectively supplying power from the higher one of the first or second auxiliary power supplies to the second fixing heater;
When the second fixing heater is driven and the second fixing heater reaches a rated current value, the output voltage of the first auxiliary power supply is set to be lower than the output voltage of the second auxiliary power supply. Image forming apparatus.   The power supply selection means is provided between a first diode provided between the first auxiliary power source and the second fixing heater, and between the second auxiliary power source and the second fixing heater. The image forming apparatus according to claim 1, comprising one diode and a second diode connected in parallel. First charge / discharge switching means for switching between discharging the first auxiliary power source and supplying the electric power to the first and second fixing heaters, or charging the first auxiliary power source with electric power from an external power source; ,
Second charge / discharge switching means for switching whether to discharge the power of the second auxiliary power source and supply it to the second fixing heater, or to charge the second auxiliary power source with power from the external power source;
Third fixing heater driving means for switching whether to drive the third fixing heater with electric power from the external power source;
State determining means for determining whether the main power switch of the image forming apparatus is in an on state or an off state;
When the main power switch is determined to be in the ON state by the state determination unit, the first and second charge / discharge switching units are switched to the discharge side, and the third fixing heater driving unit performs the third fixing. When the heater is driven and the main power switch is determined to be off by the state determination means, the first and second charge / discharge switching means are switched to the charge side and the third fixing heater drive means 3. The image forming apparatus according to claim 1, further comprising: a control unit that stops the third fixing heater by the operation of the first fixing heater. The state determination means is in a heater-on state where the first and second fixing heaters are driven when the main power switch is in an on-state, or in a heater-off state where the first and second fixing heaters are stopped. Further determine if there is,
The control means sets the first and second charge / discharge switching means only when the main power switch is determined to be in the ON state by the state determination means and only when the heater is determined to be in the ON state. The image forming apparatus according to claim 3, wherein the first and second charging / discharging switching units are switched to the charging side when switching to the discharging side and the heater off state is determined.

Images