JP4112381B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device and an image forming apparatus, and more particularly, to control power supply of a fixing device in an image forming apparatus such as a copying apparatus, a printer apparatus, and a multifunction machine in an electrophotographic process for forming an image on a sheet by a thermal fixing means. Regarding technology.
[0002]
[Prior art]
[Patent Document 1]
JP-A-5-241387 [Patent Document 2]
JP 2000-075737 A [Patent Document 3]
JP 2002-162854 A [Patent Document 4]
In an image forming apparatus such as a copying machine, a printer, or a fax machine, a fixing device is provided inside in order to fix a developed image on an image forming material such as paper. . The main part of the fixing device includes a fixing roller that heats a sheet on which unfixed toner is attached, and a pressure roller that presses and conveys the sheet. Conventionally, such a fixing device is provided with a halogen heater or the like as a heater in the fixing roller, and the inside of the fixing roller is heated by this heater to raise the roller to a predetermined temperature. However, such a heating method using a heater takes a long time to heat the fixing roller to a necessary temperature, and the loss of the heater itself is large. Therefore, conventionally, as in Patent Documents 1 to 4, by switching or simultaneously energizing a main heat source by power supplied from a commercial power source and an auxiliary heat source supplied from an auxiliary power source such as a battery or a capacitor. A method for shortening the rise time of the fixing device has been proposed.
[0003]
Specifically, according to the above-mentioned Patent Document 1, the electric power released from the secondary battery by the discharging operation of the charging / discharging unit is used as auxiliary electric power for the heating source. And the electric power from a secondary battery is supplied through a charging / discharging part. The amount of power to the heating source is increased and the start-up time from when the main power is turned on until the fixing operation is possible is shortened. The above-mentioned Patent Document 2 includes a fixing device incorporating a plurality of heating means, supplies power from the storage battery to at least one heating means among the plurality of heating means, and monitors the charge capacity of the storage battery. When the storage capacity of the storage battery is less than or equal to a predetermined value, the storage battery is charged by a commercial power source, and the charging timing and image formation productivity of the storage battery are optimized. Further, Patent Document 3 proposes an image forming apparatus that has at least one auxiliary heater that is lit by the power supplied from the storage battery and at least one main heater that is lit by the power supplied to the copying machine. Has been. Further, in Patent Document 4, at least one of the two heat sources is driven for a predetermined time when the two heat sources that generate heat when energized are started up with power that is equal to or higher than the output power of a normal commercial power source stored during standby. The power storage device and the commercial power supply are driven at the same time or at different timings, can stand up in a short time without being limited by the limit of the commercial power supply, and can reduce power consumption.
[0004]
[Problems to be solved by the invention]
However, in any of the above patent documents, since the sub heater is provided in addition to the main heater, the cost of the entire apparatus is increased, and sufficient energy saving cannot be realized.
[0005]
The present invention is for solving these problems, and it is not necessary to provide a heater dedicated to an auxiliary power supply, and it is possible to start up the fixing heater in a short time with an inexpensive and simple configuration. It is an object of the present invention to provide a fixing device and an image forming apparatus that can cut off energization of a useless heater in a mode that does not use the image forming apparatus and can realize energy saving as a result.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the fixing device of the present invention is charged by a thermal fixing unit for heating and fixing an image formed on a recording material by an image forming unit, and is charged by electric power from a commercial power source. Auxiliary power storage means that is close to the peak voltage of the commercial power supply, a heating means that is supplied with power from the commercial power supply or the auxiliary power storage means and heats the thermal fixing means, and temperature detection that detects the temperature of the thermal fixing means Means, a voltage detection means for detecting the storage voltage of the auxiliary power storage means, a temperature detected by the temperature detection means is lower than a predetermined temperature, and the storage voltage detected by the voltage detection means is higher than the rated voltage of the commercial power supply In addition, power is supplied from the auxiliary power storage means to the heating means, and the temperature detected by the temperature detecting means is higher than a predetermined temperature or detected by the voltage detecting means. And if the voltage is below the rated voltage of the commercial power supply, it is characterized in that a power supply switching means for supplying power to the heating means from the commercial power source. Therefore, it is not necessary to prepare a dedicated heat source, and the fixing rise time can be shortened with an inexpensive and simple configuration.
[0007]
In addition, the supply power switching unit is configured to supply power from the commercial power source to the heating unit when the voltage detected by the voltage detection unit is lower than the rated voltage of the commercial power source while supplying power from the auxiliary power storage unit to the heating unit. Supply. Therefore, even when power is supplied from the auxiliary power storage means to the heating means, if the storage voltage of the auxiliary power storage means is less than the rated voltage of the commercial power supply, the power from the commercial power supply to the heating means By performing the supply, it is possible to shorten the rise time of fixing.
[0011]
An image forming apparatus as another invention has the above-described fixing device, and heat-welds an electrophotographic toner image to a recording member. Therefore, the toner can be stably heated and melted, a high-quality toner image can be fixed on the recording member and formed, and a fixing heater with a simple and inexpensive structure without the need for an auxiliary power source heater can be provided. Can be started for a short time, and the energization of the useless heater can be cut off in a mode in which a normal apparatus such as the low power mode is not used. As a result, energy saving can be realized.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides power supply from the auxiliary power storage means to the heating means when the temperature detected by the temperature detection means is lower than a predetermined temperature and the stored voltage detected by the voltage detection means is higher than the rated voltage of the commercial power supply. If the temperature detected by the temperature detecting means is higher than a predetermined temperature or if the voltage detected by the voltage detecting means is equal to or lower than the rated voltage of the commercial power supply, power is supplied from the commercial power supply to the heating means. Therefore, it is not necessary to prepare a dedicated heat source, and the fixing rise time can be shortened with an inexpensive and simple configuration.
[0013]
【Example】
FIG. 1 is a schematic sectional view showing the configuration of a digital copying machine as an example of the image forming apparatus of the present invention. A digital copying machine 100 shown in FIG. 1 includes a copying machine main body 101, an automatic document feeder 102, a stapler and a finisher 103 with a shift tray capable of discharging a large amount of imaged paper, a duplex reversing unit 104, and the like. The extended sheet feeding tray 105, the large capacity sheet feeding tray 106, and the one-bin sheet discharge tray 107 are configured. The copier body 101 includes a scanner, a writing device, a photoconductor, a developing device, a paper feeding device, and the like, and the fixing device of the present invention.
[0014]
FIG. 2 is a diagram showing a configuration of a fixing device according to an embodiment of the present invention. In the figure, an AC voltage is input to a diode bridge 13 from an AC power source 11 that is a commercial power source via a power relay 12 that is an open / close element. The output of the diode bridge 13 is supplied to a heater circuit 20 including a fixing heater 18 and a switching element 19 via an input current sensor 14 and a low-pass filter unit 17 including a coil 15 and a capacitor 16. The low-pass filter unit 17 sets the capacitance of the capacitor 16 to be small so that when the switching element 19 or the switching element 21 described later is turned off, the booster output obtained by adding the voltage generated in the coil 15 and the AC power source 11 is fixed to the fixing heater 18. And can be supplied to an auxiliary power circuit 22 described later. Since the power of the fixing heater 18 is proportional to the square of the applied voltage, a larger capacity of power can be supplied when supplied from the capacitor side. In addition, the capacitor is configured to have a breakdown voltage higher than the voltage related to charging. In parallel with the heater circuit 20, a parallel circuit of a power relay 23 and a diode 24, which are switching elements, and an auxiliary power circuit 22 in which a capacitor Cp, which is a storage element, and a switching element 21 are connected in series are connected. In this embodiment, the capacitor Cp is used, but it can be replaced with a secondary battery, a primary battery, or a fuel cell. Further, an output voltage detection circuit 25 that detects the voltage of the storage element is connected. The output voltage detection circuit 25 is also provided with a display means 26 for displaying that the voltage is charged in the storage element. The fixing heater 18 is built in a fixing roller (not shown), and is provided with a thermistor 27 for detecting the temperature of the outer peripheral surface of the roller, and drive circuits 28 and 29 for switching elements of the heater circuit 20 and the auxiliary power circuit 22 are provided. Both are connected to the inverter control circuit 30. Further, the inverter control circuit 30 is also connected to a resistor 31 for detecting the input voltage of the low-pass filter unit 17, a voltage divider circuit 33 for the resistor 32, and the input current sensor 14. Further, the engine control unit 34 and the inverter control circuit 30 of the image forming apparatus main body share the setting value of the fixing roller temperature, the detection signal in the fixing device, the on / off signal of the auxiliary power source, and the like by communication. Here, a portion surrounded by a broken line in the drawing is called an inverter 10. Note that the capacitor of the auxiliary power supply circuit 22 uses an electric double layer capacitor because a capacitor having a large capacitance can be made for a small size. In addition, since the storage element is intended to store charges, it may be another storage element, such as an aluminum electric field capacitor.
[0015]
FIG. 3 is a flowchart showing the control operation of the entire fixing device of this embodiment. In FIG. 2, the inverter control circuit 30 in FIG. 2 controls the temperature of the fixing heater 18 in FIG. 2 (step S101), and further controls the lighting of the fixing heater 18 (step S102). Then, charging control of the auxiliary power circuit 22 of FIG. 2 is performed (step S103), and communication with the engine control unit 34 of FIG. 2 of the image forming apparatus main body is performed (step S104).
[0016]
FIG. 4 is a flowchart showing the lighting control operation of the fixing heater in the fixing device of this embodiment. In the figure, when the signal for turning on the fixing heater 18 is output from the engine control unit 34 in FIG. 2, the inverter control circuit 30 determines whether the fixing heater 18 is energized by the AC power supply 11 or the auxiliary power supply circuit 22. The heater is energized. The heater circuit 20 and the auxiliary power supply circuit 22 are energized by the drive circuits 28 and 29, and the fixing heater 18 or the storage element is energized by turning on (conducting) the switching elements 19 and 21. The conduction ratio of the switching element is controlled in accordance with the value of current that flows to the load (heater and capacitor). Charging to the auxiliary power circuit 22 is performed via the diode 24, and energization from the auxiliary power circuit 22 to the fixing heater 18 is performed by closing the relay 23, which is an opening / closing element, and bypassing the diode 24. In the lighting control of the fixing heater 18, it is determined whether or not the apparatus is started, that is, when the power is turned on or when the temperature of the fixing roller is returned from the energy saving mode where the temperature of the fixing roller is set to a low level. Is a target temperature, for example, 180 ° C. or less (step S201; YES), and the charging voltage of the storage element is a reference voltage close to the peak voltage of the AC power source 11, for example, 110V or more (step S202; YES), AC The power relay 12 of the power source 11 is opened, the power relay 23 of the auxiliary power system is closed, and the fixing heater 18 is energized (duty lighting) from the auxiliary power circuit 22 (steps S203 and S204). Since a capacitor is used as the power storage element, when the fixing power supply 18 is energized from the auxiliary power supply circuit 22, the charging voltage decreases due to discharging. For this reason, the charging voltage is monitored by the output voltage detection circuit 25, and when discharging progresses and drops below the voltage of the AC power supply 11, the DC charging voltage of the storage element is specifically the rated voltage of the AC power supply 11, that is, the product standard. When the voltage drops to 100 V or lower, which is an allowable value in accordance with safety standards (step S202; NO), the auxiliary power system power relay 23 is opened and switched to energization from the AC power system (steps S205 and S206). Selection of the power source for energizing the fixing heater 18, that is, the AC power source 11 or the auxiliary power circuit 22, can be performed at an arbitrary timing.
[0017]
Next, an operation for energizing the fixing heater from the AC power source in the fixing device of this embodiment will be described with reference to FIG.
First, the conduction ratio of the switching element 19 is controlled by the inverter control circuit 30 of FIG. 2 so that the temperature of the fixing roller in which the fixing heater 18 is built becomes a predetermined value. Specifically, the inverter control circuit 30 performs duty control on the drive circuit 28 of the switching element 19 that drives the fixing heater 18 so that the temperature detected by the thermistor 27 in FIG. 2 becomes a target value, for example, 180 ° C. The PWM signal (pulse width modulation signal) is output. The switching operation of the switching element 19 is performed at a constant frequency, for example, 20 kHz and a cycle of 50 μS, and the conduction ratio and the input current are almost proportional. This conduction ratio value is also output to the engine control means. Since the halogen heater is used as the fixing heater 18 and has a low impedance at a low temperature, there is a characteristic that an inrush current flows at start-up (when lighting). For this reason, the input current is detected by the input current sensor 14 of FIG. 2 including the suppression of the inrush current, and control according to the input current of the inverter 10 is performed. Specifically, the duty control is performed when the fixing heater is turned on or the storage element is charged so that the input current becomes a predetermined value or less. This control is the same regardless of whether the AC power supply or the auxiliary power supply circuit is energized. When the temperature of the fixing heater 18 (fixing roller) is equal to or lower than a target value, for example, 180 ° C. (step S301; YES), input is performed. The conduction ratio (Duty) of the PWM signal is increased or decreased depending on whether or not the current is equal to or less than the target value set for each operation mode of the image forming apparatus (step S302). When the input current is equal to or less than the target value set for each operation mode of the image forming apparatus (step S302; YES), the PWM signal conduction ratio (Duty) is increased (step S303). On the other hand, when the input current is larger than the target value set for each operation mode of the image forming apparatus (step S302; NO), the conduction ratio (duty) of the PWM signal is decreased (step S304). When the temperature of the fixing heater 18 (fixing roller) is higher than the target value (step S301; NO), the fixing heater 18 is turned off.
[0018]
Next, the charging operation for the storage element will be described. The energization (charging) from the AC power supply 11 to the auxiliary power supply circuit 22 in FIG. 2 is performed whenever the input current It from the AC power supply 11 has a margin. . However, priority is given to energization of the fixing heater 18. Here, when the target temperature and the current temperature of the fixing heater 18 are lower than a predetermined value, for example, 20 ° C. or higher, charging to the auxiliary power supply circuit 22 is interrupted and directed to energizing the fixing heater 18. Yes. In the inverter control circuit 30 of FIG. 2, when the detected value of the input current sensor 14 is equal to or less than a predetermined value, the conduction ratio of the switching element 21 is controlled to charge the storage element from the AC power source 11. The charging current (input current from the AC power source) changes in proportion to the conduction ratio as in the case of the above-described fixing heater. Since the AC power supply 11 has a full-wave rectified waveform, charging is performed via a diode 24 for preventing backflow. The charging current flows when a voltage higher than the current charging voltage of the capacitor of the power storage means is input from the AC power supply 11. The switching element 21 uses an element capable of energizing in both polarities, for example, an FET (field effect transistor), and is turned on by a signal from the drive circuit 29 in FIG. However, as is generally known, when a FET is used as the switching element, a parasitic diode exists in parallel between the drain and the source, so that the voltage of the AC power supply 11 is maintained even when the switching element 21 is non-conductive. When the voltage is lower than the voltage of the storage element, a discharge current (reverse flow) flows through this diode. The diode 24 also serves to prevent a backflow that occurs during charging. In addition, the output voltage detection circuit 25 of FIG. 2 detects the charging voltage of the storage element, and when it reaches a full charge voltage, for example, 130 V, the switching element 21 is turned off to end the charging.
[0019]
Next, the operation of energization from the auxiliary power supply circuit to the fixing heater will be described. When power is supplied from the auxiliary power supply circuit 22 to the heater circuit 20, the power relay 12 of FIG. Is closed, and the power relay 23 of the auxiliary power circuit 22 is closed. Further, the conduction ratio of the switching element 21 is set to 100% (always on). As described above, even if the switching element 21 is not turned on, discharging can be performed by the parasitic diodes present in parallel. However, the resistance (on-resistance) when the switching element 21 is conductive is the forward direction of the parasitic diode. The value is sufficiently low with respect to the voltage. For example, the voltage drop due to the on-resistance is 0.2V while the voltage drop at the parasitic diode is 0.7V. Therefore, the switching element 21 is made conductive to positively discharge to reduce loss due to voltage drop. A voltage is supplied from the auxiliary power source to the fixing heater through such a path, and the conduction control of the fixing heater is performed in the same manner as in the case of energization from the AC power source.
[0020]
In addition, this invention is not limited to the said Example, It cannot be overemphasized that various deformation | transformation and substitution are possible if it is description in a claim.
[0021]
【The invention's effect】
As described above, the fixing device according to the present invention includes the thermal fixing unit for heating and fixing the image formed on the recording material by the image forming unit, and the commercial power source that is charged by the power from the commercial power source. Auxiliary power storage means having a voltage close to the peak voltage of the power supply, power supplied from a commercial power source or auxiliary power storage means, heating means for heating the thermal fixing means, temperature detection means for detecting the temperature of the thermal fixing means, A voltage detection means for detecting the storage voltage of the auxiliary power storage means, and an auxiliary when the temperature detected by the temperature detection means is lower than a predetermined temperature and the storage voltage detected by the voltage detection means is higher than the rated voltage of the commercial power supply. The power supplied from the power storage means to the heating means, and the temperature detected by the temperature detection means is higher than a predetermined temperature or the voltage detected by the voltage detection means In the case of the rated voltage of the commercial power source, it is characterized in that a power supply switching means for supplying power to the heating means from the commercial power source. Therefore, it is not necessary to prepare a dedicated heat source, and the fixing rise time can be shortened with an inexpensive and simple configuration.
[0022]
In addition, the supply power switching unit is configured to supply power from the commercial power source to the heating unit when the voltage detected by the voltage detection unit is lower than the rated voltage of the commercial power source while supplying power from the auxiliary power storage unit to the heating unit. Supply. Therefore, even when power is supplied from the auxiliary power storage means to the heating means, if the storage voltage of the auxiliary power storage means is less than the rated voltage of the commercial power supply, the power from the commercial power supply to the heating means is By performing the supply, it is possible to shorten the rise time of fixing.
[0026]
An image forming apparatus as another invention has the above-described fixing device, and heat-welds a toner image formed by electrophotography to a recording member. Therefore, the toner can be stably heated and melted, a high-quality toner image can be fixed on the recording member and formed, and a fixing heater with a simple and inexpensive structure without the need for an auxiliary power source heater can be provided. Can be started for a short time, and the energization of the useless heater can be cut off in a mode in which a normal apparatus such as the low power mode is not used. As a result, energy saving can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a configuration of a digital copying machine as an example of an image forming apparatus of the present invention.
FIG. 2 is a diagram illustrating a configuration of a fixing device according to an embodiment of the present invention.
FIG. 3 is a flowchart illustrating a control operation of the entire fixing device according to the present exemplary embodiment.
FIG. 4 is a flowchart illustrating a lighting control operation of a fixing heater in the fixing device according to the present exemplary embodiment.
FIG. 5 is a flowchart illustrating an energization operation from an AC power source to a fixing heater in the fixing device according to the present exemplary embodiment.
[Explanation of symbols]
10; inverter circuit, 11; AC power supply, 12, 23; power relay,
13; diode bridge, 14; input current sensor, 15; coil,
16; capacitor, 17; low-pass filter section, 18; fixing heater,
19, 21; switching element, 20; heater circuit, 22; auxiliary power circuit,
24; diode; 25; output voltage detection circuit; 26; display means;
27; thermistor, 28, 29; drive circuit, 30; inverter control circuit,
31, 32; resistance, 33; voltage dividing circuit, 34; engine control unit.

Claims (3)

A heat fixing means for heat fixing an image formed on the recording material by the image forming means;
Auxiliary power storage means that is charged by the power from the commercial power supply and becomes a voltage close to the peak voltage of the commercial power supply when fully charged ,
A heating unit that is supplied with power from the commercial power source or the auxiliary power storage unit and heats the thermal fixing unit;
Temperature detecting means for detecting the temperature of the heat fixing means;
Voltage detection means for detecting the storage voltage of the auxiliary power storage means;
Power supply from the auxiliary power storage means to the heating means when the temperature detected by the temperature detection means is lower than a predetermined temperature and the stored voltage detected by the voltage detection means is higher than the rated voltage of the commercial power supply When the temperature detected by the temperature detection means is higher than a predetermined temperature or the voltage detected by the voltage detection means is less than the rated voltage of the commercial power supply, the power from the commercial power supply to the heating means A fixing device comprising: a power supply switching means for performing supply.   When the voltage detected by the voltage detection unit when power is supplied from the auxiliary power storage unit to the heating unit is equal to or lower than the rated voltage of the commercial power source, The fixing device according to claim 1, wherein power is supplied to the heating unit.   An image forming apparatus comprising the fixing device according to claim 1, wherein a toner image formed by electrophotography is heat-welded to a recording member.

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