JP2008226856A - Heating device, fixing device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily restrain the input current from the commercial power supply to a rated current or less, when performing charging to an electric double layer capacitor being an auxiliary power supply. <P>SOLUTION: The device comprises: an electric double layer capacitor 116 for supplying electric power to a sub-heater 119; a rectification/charging circuit 113 for charging the electric double layer capacitor 116; an input current detecting part 111 for detecting the input current of the commercial power supply 110; a voltage detecting part 115 for detecting the charged voltage of the electric double layer capacitor 116; a charge and discharge switching part 114 for switching over whether to charge the electric double layer capacitor 116 or to discharge to the sub-heater 119, or not to charge/discharge the electric double layer capacitor 116; and a control/drive part 101 which controls the charging volume of the electric double layer capacitor 116 to a constant power based on the voltage of the commercial power supply 110, the input current at the input current detecting part 115, and the charged voltage at the voltage detecting part 115. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heating device, a fixing device, and an image forming apparatus mounted on a laser printer, a copying machine, and the like, and more specifically, for shortening the startup time of the fixing device and shortening the recovery time from the energy saving mode. The present invention relates to a heating device, a fixing device, and an image forming apparatus related to a charging method for an electric double layer capacitor that supplies current to a sub-heater.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a laser printer, or a facsimile machine, a fixing device is provided in the inside in order to fix a developed image on an image forming material such as recording paper. The main part of the fixing device is composed of a fixing roller for heating the recording paper to which the unfixed toner is transferred, and a pressure roller for pressing, nipping and transporting the recording paper. Such a fixing device includes a halogen heater or the like as a heater in the fixing roller, and heats the inside of the fixing roller with this heater to raise the roller to a predetermined temperature.

  In an image forming apparatus equipped with such a heat fixing device, the power saving effect is enhanced, noise due to an inrush current or a sudden current change when supplying large power is reduced, the rise time is shortened, and the temperature rises. An apparatus using an energization control method for preventing the excess is disclosed (for example, see Patent Document 1). In addition, a device is disclosed in which a secondary battery as an auxiliary power source is charged during standby of the device, and power is supplied from the secondary battery in addition to the main power source when the device is warmed up to shorten the rise time (for example, , See Patent Document 2).

  On the other hand, the present applicant provides an input voltage / current detection means in the commercial power supply input unit of the image forming apparatus, and when the input current or input power is equal to or less than the threshold value, the electric current is charged to the electric double layer capacitor by a difference from the threshold value. The device which performs is proposed previously. Here, proposals have been made regarding the timing and amount of charge to the capacitor of the auxiliary power supply circuit. Specifically, an input voltage / current detection unit is provided in the commercial power input unit of the image forming apparatus, and when the input current or input power is equal to or less than the threshold, the electric double layer capacitor is charged with a constant current according to a difference from the threshold. It is configured.

JP 2002-184554 A Japanese Patent Laid-Open No. 10-282821

  In the recent heating method using a heater, it takes a long time to heat the fixing roller to a necessary temperature, and the loss of the heater itself is large. At present, environmental problems such as global warming are highlighted, and there is a demand for a fixing device that is efficient and has a fast rise time.

  However, in the conventional technique as described above, the fixing device disclosed in Patent Document 1 charges a secondary battery as an auxiliary power supply during standby, and the main power supply device and the secondary battery during startup. Power is being supplied from. A disadvantage of this fixing device is that a secondary battery is used as an auxiliary power source.

  Secondary batteries generally include CADNICA batteries, lead-acid batteries, etc., but these secondary batteries cause a decrease in capacity when repeated charging and discharging, and are said to have a shorter life as they are discharged at higher currents. . Even in the case of a CADNICA battery which is generally said to have a long current with a large current, the number of charge / discharge cycles is about 500 to 1000 times. If it is mounted on the image forming apparatus and charged / discharged 20 times per day, the battery life will be reached in about one month, and the running cost such as the labor and time for replacement will be very expensive. In the case of a lead storage battery, sulfuric acid is used, which is not preferable as an office device. Also, secondary batteries cannot be rapidly charged, and even if they are said to be fast, several tens of minutes are necessary for full charging.

  On the other hand, in Patent Document 2, a capacitor is used as an auxiliary power source in place of the secondary battery. The heating unit is provided with a main heating element and an auxiliary heating element. The main heating element is supplied with electric power from the main power supply unit, and the auxiliary heating element is supplied with electric power from an auxiliary power supply unit having a capacitor. It is disclosed that a large amount of electric power is supplied from the device and the auxiliary power supply device, and the heating unit is raised to a predetermined temperature in a short time and power is not supplied to the heating unit during standby. There is no mention of charging timing and charging amount for the capacitor of the power supply circuit.

  In addition, when performing constant current charging, the charging voltage of the electric double layer capacitor increases and the power required for constant current charging increases as it approaches full charge, so the constant current charge value is calculated at the start of charging, and then constant. If constant current charging is continued without recalculating the constant constant current charge value, there is a possibility that a current of 15 A (general current rating of Japanese 100V commercial power supply) or more will be input from the commercial power supply. . Specific examples are shown below.

Here, the constant current charge value is calculated assuming that the following conditions are satisfied at the start of the electric double layer capacitor.
Threshold: 14.5A (General current rating of Japanese 100V commercial power supply: 15A to 0.5A margin)
Input current from commercial power supply: 10A
Commercial power supply voltage: AC100V
Charging voltage of electric double layer capacitor: DC20V
Conversion efficiency of rectification and charging means: 80%
Constant current charge value = (surplus input power x conversion efficiency) / charge voltage
= (100 × (14.5-10) × 0.8) / 20
= 18 (A)

As a result of the above calculation, constant current charging to the electric double layer capacitor is started at 18 (A). When a constant time has elapsed since the start of constant current charging, the current consumed (10 A) other than charging the electric double layer capacitor is unchanged, and the charging voltage becomes 24 (V). The current is
Input current from commercial power supply = Current consumption other than for charging purposes + ((charging voltage x constant current charge value) / conversion efficiency) / commercial power supply voltage)
= 10 + ((24 × 18) /0.8) / 100)
= 15.4 (A)
Is calculated in reverse and exceeds 15 (A), which is a general rated current of 100V commercial power supply in Japan.

  Thus, since the charging method to the electric double layer capacitor is constant current charging, if constant current charging is continued for a certain period of time, it will be 15A (general rated current of Japanese 100V commercial power supply) or more from the commercial power supply. There is a possibility that current may be input (see FIG. 5).

  The present invention has been made in view of the above, and an object of the present invention is to easily suppress an input current from a commercial power source to a rated current or less when charging an electric double layer capacitor as an auxiliary power source. .

  In order to solve the above-described problems and achieve the object, the invention according to claim 1 is the heating device according to claim 1, wherein the main heating element that generates heat by the current supplied from the commercial power source, and the direct current An auxiliary heating element that generates heat from a power source, a chargeable / dischargeable auxiliary power source that supplies power to the auxiliary heating element, rectifies a current supplied from the commercial power source, and the auxiliary power source Charging means for charging; input current detecting means for detecting an input current from the commercial power supply; charging voltage detecting means for detecting a charging voltage of the auxiliary power supply; and charging the auxiliary power from the charging means. 1 state, a second state in which discharge from the auxiliary power source to the auxiliary heating element, and a third state in which neither charging nor discharging of the auxiliary power source is performed are switched according to a predetermined signal. The charging current is calculated so that the charge amount of the auxiliary power source becomes constant power based on the voltage of the replacement means, the voltage of the commercial power supply, the input current by the input current detection means, and the charging voltage by the charging voltage detection means And a control means for controlling charging by the charging means in accordance with the result of the calculation.

  According to the present invention, in a heating device having a main heating element that generates heat due to a current supplied from a commercial power supply and an auxiliary heating element that generates heat from a DC power supply, the voltage of the commercial power supply and the input current by the input current detection means The charging current is calculated based on the charging voltage by the charging voltage detection means so that the charging amount of the auxiliary power source becomes constant power, and the charging by the charging means is controlled according to the result of the calculation. The input current can be suppressed below the rated current.

  Further, the invention according to claim 2 further includes a charging current storage unit that stores in advance a charging current specified value of the charging unit, and the control unit stores the charging stored in the charging current storage unit. When the calculated charging current value exceeds the specified current value, the charging means is controlled according to the specified charging current value to perform constant current control.

  According to this invention, in the heating device according to claim 1, when the calculated charging current value exceeds the charging current specified value stored in the charging current storage means, charging is performed according to the charging current specified value. By controlling the means and executing the constant current control, it is possible to avoid a situation where the battery is inadvertently charged with a large current in a region where the charging voltage is low.

  The invention according to claim 3 includes a main heating element that generates heat due to a current supplied from a commercial power supply, and an auxiliary heating element that generates heat from a DC power supply, and is controlled to a predetermined fixing temperature. In the fixing device, a chargeable / dischargeable auxiliary power supply for supplying power to the auxiliary heating element, a charging means for rectifying a current supplied from the commercial power supply, and charging the auxiliary power supply, and a power supply from the commercial power supply Input current detecting means for detecting an input current; charging voltage detecting means for detecting a charging voltage of the auxiliary power supply; a first state in which charging to the auxiliary power from the charging means; and from the auxiliary power supply to the auxiliary power Switching means for switching between a second state in which the heating element is discharged and a third state in which neither charging nor discharging of the auxiliary power is performed according to a predetermined signal, the voltage of the commercial power, and the input Based on the input current by the current detecting means and the charging voltage by the charging voltage detecting means, the charging current is calculated so that the charging amount of the auxiliary power source becomes constant power, and charging by the charging means is performed according to the result of the calculation And a control means for controlling.

  According to the present invention, in a fixing device having a main heating element that generates heat due to a current supplied from a commercial power supply and an auxiliary heating element that generates heat from a DC power supply, the voltage of the commercial power supply and the input current from the input current detection means The charging current is calculated based on the charging voltage by the charging voltage detection means so that the charging amount of the auxiliary power source becomes constant power, and the charging by the charging means is controlled according to the result of the calculation. The input current can be suppressed below the rated current.

  The invention according to claim 4 further includes a charging current storage unit that stores in advance a charging current specified value of the charging unit, and the control unit stores the charging current stored in the charging current storage unit. When the calculated charging current value exceeds the specified current value, the charging unit and the charging unit are controlled according to the specified charging current value to perform constant current control.

  According to this invention, in the fixing device according to claim 3, when the calculated charging current value exceeds the charging current specified value stored in the charging current storage means, charging is performed according to the charging current specified value. By controlling the means and executing the constant current control, it is possible to avoid a situation where the battery is inadvertently charged with a large current in a region where the charging voltage is low.

  The invention according to claim 5 is characterized in that the heating device according to claim 1 or 2 or the fixing device according to claim 3 or 4 is used.

  According to this invention, the amount of charge to the auxiliary power source does not exceed the rated current by mounting the heating device according to claim 1 or 2 or the fixing device according to claim 3 or 4 on the image forming apparatus. It becomes possible to be a range.

  A heating device according to the present invention (Claim 1) is a heating device having a main heating element that generates heat by a current supplied from a commercial power source and an auxiliary heating element that generates heat from a DC power source, Based on the input current by the current detecting means and the charging voltage by the charging voltage detecting means, the charging current is calculated so that the charging amount of the auxiliary power source becomes constant power, and the charging amount by the charging means is calculated according to the result of the calculation. Therefore, when charging the electric double layer capacitor, which is an auxiliary power supply, an effect is obtained that the input current from the commercial power supply can be easily suppressed to a rated current or less.

  According to the heating device of the present invention (Claim 2), according to the heating device of the present invention (Claim 2), the charging current regulation stored in the charging current storage means in the heating device of Claim 1 is provided. If the calculated charging current value exceeds the value, the charging means is controlled according to the charging current regulation value and the constant current control is executed, so that the charging voltage is inadvertently charged with a large current in a low charging voltage region. Therefore, it is possible to select a component with a low rated current as a component that constitutes charging or switching of charging, and the effect of improving the economy is achieved.

  A fixing device according to the present invention (Claim 3) is a fixing device having a main heating element that generates heat due to a current supplied from a commercial power source and an auxiliary heating element that generates heat from a DC power source. The charging current is calculated based on the input current by the input current detecting means and the charging voltage by the charging voltage detecting means so that the charging amount of the auxiliary power source becomes constant power, and charging by the charging means is performed according to the result of the calculation. Therefore, when charging the electric double layer capacitor, which is an auxiliary power source, the effect is that the input current from the commercial power source can be easily suppressed below the rated current.

  According to the fixing device of the present invention (Claim 4), in the fixing device according to Claim 3, when the calculated charging current value exceeds the charging current specified value stored in the charging current storage means. Since the charging means is controlled according to the charging current regulation value and the constant current control is executed, it is possible to avoid a situation where the charging voltage is inadvertently charged with a large current in a low charging voltage region. Therefore, it is possible to select a part with a low rated current as a part constituting the switching or the like, thereby improving the economy.

  An image forming apparatus according to the present invention (Claim 5) is provided with an auxiliary power source by mounting the heating apparatus according to Claim 1 or 2 or the fixing apparatus according to Claim 3 or 4 on the image forming apparatus. Therefore, it is possible to provide an image forming apparatus that can easily limit the amount of charge to a range that does not exceed the rated current.

  Preferred embodiments of a heating device, a fixing device, and an image forming apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. The present invention is not limited to this embodiment.

  In the present invention, the electric double layer capacitor as an auxiliary power source is calculated so that the amount of charge is constant power, and the input current from the commercial power source is limited to a rated current or less. In addition, the determination of the charging amount is switched between constant power and constant current according to the charging voltage value of the electric double layer capacitor, and charging with an excessively large current in a region where the charging voltage is low is avoided. This will be specifically described below.

  First, a detailed configuration of the image forming apparatus will be described. FIG. 1 is an explanatory diagram showing a configuration of a digital copying machine that is an image forming apparatus according to an embodiment of the present invention. The configuration is mainly composed of a scanner unit 1 and a printer unit 2.

  The scanner unit 1 includes a contact glass 3, a light source 4, a first mirror 5, a second carriage 6 having a second mirror 7 and a third mirror 8, a stepping motor 9, a fourth mirror 10, a lens 11, and a CCD image sensor 12. It has.

  The printer unit 2 includes an image reproducing system (image forming system) and a paper feeding system. The image forming system includes a photosensitive drum 15, a charging charger 16, an eraser 17, a developing unit 18, a transfer charger 19, a separation charger 20, a separation claw 21, a cleaning unit 22, and a laser writing unit 35.

  In addition, the printer unit 2 has two paper feeding systems, that is, an upper paper feeding cassette 26 and a manual paper feeding table 27, and a lower paper feeding cassette 29. The recording paper set on the upper paper cassette 26 and the manual paper feeder 27 is fed by a paper feed roller 28. The recording paper in the lower paper feed cassette 29 is fed by the paper feed roller 30.

  The laser writing unit 35 includes an LD unit, an fθ lens, a polygon scanner, a mirror, and the like.

  In FIG. 1, reference numeral 23 is a conveyor belt, reference numeral 24 is a fixing device, reference numeral 25 is a fixing roller, reference numeral 26 is a pressure roller, reference numeral 27 is a temperature measuring device such as a thermistor, reference numeral 28 is a main motor, and reference numeral 29 is a main motor. A paper discharge tray, 31 is a registration roller.

  Next, in the digital copying machine configured as described above, first, the scanner unit 1 will be described. The document set at a predetermined position of the contact glass 3 in the scanner unit 1 is irradiated by the light source 4, and the reflected light passes through the first mirror 5 to the second mirror 7, the third mirror 8, the fourth mirror 10, and the lens 11. Then, an image is formed on the light receiving surface of the CCD image sensor 12. The light source 4 and the first mirror 5 are mounted on a first carriage that moves in the sub-scanning direction in parallel with the contact glass 3 on the lower surface of the contact glass 3, and reflected light from the first carriage is driven by a stepping motor 9. The stepping motor 9 is supplied with a phase excitation signal by a driver mounted on a sequence control unit (not shown).

  The CPU of the sequence control unit outputs a control clock to the stepping motor driver, and switches the phase excitation signal output from the driver. The second carriage 6 moves in the sub-scanning direction at a half speed in conjunction with the first carriage. The scanning in the main scanning direction is performed by scanning with the CCD image sensor 12, and the entire original is optically scanned by moving the optical system as described above.

  Next, the printer unit 2 will be described. As described above, the laser writing unit 35 includes an LD unit, an fθ lens, and a mirror. Inside the LD unit, a laser diode (LD) as a laser light source is provided. The polygon scanner is provided with a polygon mirror that is rotated at high speed by an electric motor. The rotation control of the polygon scanner is performed by a writing control ASIC mounted on the writing control board, and the writing control ASIC can rotate the polygon mirror of the polygon scanner at an arbitrary number of rotations by changing the frequency of the rotation control clock. Is possible. The laser beam output from the laser writing unit 35 is applied to the photosensitive drum 15 of the image reproduction system.

  Next, an image reproduction (image forming) process in the printer unit 2 will be briefly described. This process is performed according to a known electrophotographic process. First, the surface of the photosensitive drum 15 is uniformly charged to a high potential by the charging charger 16. Subsequently, when the surroundings are irradiated with laser light, the potential of the irradiated portion decreases. Since the laser light is ON / OFF controlled according to black / white for recording / reproduction, the potential distribution corresponding to the recorded image, that is, the electrostatic latent image is formed on the surface of the photosensitive drum 15 by the irradiation of the laser light. The

  When the portion where the electrostatic latent image is formed passes through the developing unit 18, toner adheres according to the level of the potential, and the electrostatic latent image becomes a visualized toner image. In addition, recording paper is fed from a cassette described later at a predetermined timing to a portion where the toner image is formed, and overlaps the toner image. This toner image is transferred onto a recording sheet by the discharge of the transfer charger 19. Thereafter, the recording paper is separated from the photosensitive drum 15 by the discharge of the separation charger 19 and the electrical and mechanical action of the separation claw 20.

  The separated recording paper is conveyed by the conveying belt 23, heated and fixed by a fixing roller 25 having a built-in heater, and then discharged to a paper discharge tray 29. In this embodiment, as shown in FIG. 1, the printer unit 2 has two paper feeding systems. The recording paper set on the upper paper cassette 26 and the manual paper feeder 27 is fed by a paper feed roller 28. The recording paper in the lower paper feed cassette 29 is fed by the paper feed roller 30.

  Then, the recording paper fed from one of the paper feed rollers is temporarily stopped in contact with the registration roller 31 and sent to the photosensitive drum 15 at a timing synchronized with the progress of the image formation (image reproduction) process. It is.

  The fixing device 24 includes a temperature measuring device 27 that measures the surface temperature of the fixing roller 25. The temperature measuring device is installed in contact with the surface of the fixing roller 25. Although not shown, the software can recognize the surface temperature of the fixing roller 25 by inputting the voltage from the temperature measuring device to the AD converter of the CPU mounted on the sequence control board.

  FIG. 2 is a block diagram showing a main configuration of the image forming apparatus according to the embodiment of the present invention. In the figure, reference numeral 100 denotes an image forming apparatus configured as shown in FIG. 1, reference numeral 101 denotes a control / drive unit for comprehensively controlling the image forming apparatus 100, reference numeral 102 denotes a nonvolatile memory, and reference numeral 103 is described later. In this way, a charge amount calculation unit for calculating the charge amount to the electric double layer capacitor, reference numeral 104 denotes a scanner motor (corresponding to the stepping motor 9 in FIG. 1) for driving the scanner field operation, reference numeral 105 denotes a photoreceptor of this apparatus, etc. 1 is a main motor (corresponding to the main motor 28 in FIG. 1), 106 is a developing motor that drives a roller of the developing device, 107 is a paper feeding clutch that transmits driving to the paper feeding roller, etc. Reference numeral 108 denotes a cooling fan for suppressing temperature rise in the apparatus and diluting the generated gas.

  Reference numeral 110 is a commercial power source, reference numeral 111 is an input current detection unit, reference numeral 112 is a power source unit, reference numeral 113 is a rectification / charging circuit that rectifies current from the commercial power source and charges the auxiliary power source, and reference numeral 114 is an auxiliary power source. Charge / discharge switching unit, reference numeral 115 is a voltage detection unit for detecting the charging voltage of the auxiliary power source, reference numeral 116 is an electric double layer capacitor as an auxiliary power source, reference numeral 117 is a heating unit, and reference numeral 118 is AC power. Reference numeral 119 denotes a sub-heater that heats the fixing roller by a DC power source, and reference numeral 120 denotes a temperature sensor that uses an element such as a thermistor that detects the surface temperature of the fixing roller.

  That is, in the fixing unit 24 of the image forming apparatus 100, the thickness of the cored bar portion is reduced so that the surface of the fixing roller reaches a predetermined temperature in a short time, and the main heater 118 and the sub-heater 119 are incorporated therein, and the temperature rises. It is a so-called twin heater type heat roll structure that shortens the time.

  Next, each input / output signal and the like will be described with reference to FIG. The input current detection unit 111 detects the input current of the commercial power supply 110 and feeds back the input current data to the control / drive unit 101. The voltage detector 115 detects the charging voltage of the electric double layer capacitor 116 and supplies it to the charge amount calculator 103 as charging voltage data. The charge amount calculation unit 103 calculates the charge amount, and sends a charge amount instruction value to the rectification / charge circuit 113 according to the calculation result. The control / drive unit 101 sends a charge / discharge switching control signal to the charge / discharge switching unit 114 to control switching by the charge / discharge switching unit 114.

  The temperature heater 120 detects the surface temperature of the fixing roller and feeds it back to the control / drive unit 101 as temperature data. The control / drive unit 101 sends a main heater control signal to the switching element of the main heater 118 to control on / off of the main heater 118. The surface temperature of the fixing roller is controlled to be 180 ° C., for example, during fixing, and is controlled to a lower temperature in the energy saving mode.

  The power supply unit 112 generates power supply voltages such as 5V, 24V, and 38V and supplies them to the control / drive unit 101. The control / drive unit 101 sends a drive signal to each of the scanner motor 104, the main motor 105, the developing motor 106, the paper feed clutch 107, and the cooling fan 108 at a predetermined timing and supplies a predetermined drive voltage.

  The electric double layer capacitor 116 can be rapidly charged with a large current, and has an advantage that charging is completed in a time of several seconds to several tens of seconds. Electric energy stored in the electric double layer capacitor 116 is supplied to the sub-heater 119 according to a charge / discharge switching control signal from the drive / control unit 101 to the charge / discharge switching unit 114 when recovering from an energy saving mode such as low power and sleep. Thus, the recovery time is greatly shortened.

  When the image forming apparatus 100 is turned on, if there is electric energy stored in the electric double layer capacitor 116, the drive / control unit 101 transfers to the charge / discharge switching unit 114 as in the recovery described above. Power is supplied to the sub-heater 119 according to the charge / discharge switching control signal, and the rise time is greatly shortened. The power supply to the sub-heater 119 may be either independent or combined in the energy saving mode and at the start-up time.

  By the way, in the international energy star which is an international energy saving standard, in the case of a copying machine (20∠ CPM (number of copies output per minute) ≦ 44), the standby mode is 15 minutes after the copying is completed, and then the low power mode. It is defined as 45 minutes. According to the copier energy conservation law, if the rise time is 30 seconds or less, the transition time to the low power mode may be set to 15 minutes or less. Allowed by legal guidelines.

Since the rise time within 30 seconds is facilitated by this embodiment, the standby time after the end of the copy operation can be set to 1 minute, for example. In this embodiment, the power is supplied from the electric double layer capacitor to the sub-heater at the time of start-up, 800 W for 30 seconds, 1500 W for 2 minutes for copying, 1 minute for standby (1500 W for 30 seconds with standby charging, 180 W for 30 seconds without standby charging), low power When the mode is 80 W 56 minutes 30 seconds, the energy consumption efficiency is 146 Wh / h, which greatly satisfies the 2006 standard.
(800 × 0.5) + (1500 × 2) + (1500 × 0.5) + (180 × 0.5) + (80 × 56.5) / 600

  In addition, power can be supplied to the sub-heater during recovery from the low power mode, and the recovery time can be shortened so that the power in the low power mode can be reduced with respect to the recovery time regulation of 30 seconds from the low power mode. In addition, it is possible to further reduce the set temperature of the fixing unit in the low power mode, which not only reduces the energy consumption efficiency but also reduces the low power mode power of the International Energy Star, thereby contributing to energy saving. Even when the rise time of 30 seconds cannot be achieved, the power consumption in the low power mode for 15 minutes can be reduced, so that the energy consumption efficiency can be improved. If these are combined, and the shortening of the rise time and the shortening of the recovery time are combined, an energy saving effect can be further obtained.

  In this way, for example, it is possible to perform an operation that does not exceed the maximum current of 15A. Furthermore, since the fluctuation of the input current is reduced, the voltage fluctuation of the commercial power supply is improved and the quality of the commercial power supply is improved. Specifically, the voltage fluctuates with a sudden change in the input current, and it is possible to suppress the occurrence of problems such as flickering of lighting and malfunction of peripheral electronic devices. Unlike a secondary battery or a normal electrolytic capacitor, an electric double layer capacitor is said to have no repeated life deterioration. Accordingly, when the power is turned on as in the image forming apparatus, the image forming operation, standby, and energy saving mode (low power, sleep) modes and power on / off can be repeated without worrying about the service life.

  In the image forming apparatus 100 configured as described above, first, the input current from the commercial power supply 110 detected by the input current detection unit 111 is detected by a commercial power supply voltage detection unit (not shown) or specified in advance. The electric power that can be used to charge the electric double layer capacitor 116 is calculated from the commercial power supply voltage that is determined as a value and stored in the nonvolatile memory 102 and the input current threshold value. A typical current rating of a Japanese 100V commercial power supply is 15A, but load fluctuations in applications other than charging of the electric double layer capacitor 116, such as a load caused by turning on the scanner motor 104, the main motor 105, etc. in FIG. A slight margin is taken in consideration of the fluctuation, and here, the input current threshold value is assumed to be 14.5A.

  The rectifying / charging circuit 113 rectifies and smoothes the AC power input from the commercial power source 110 and converts it to a DC power source. However, a certain amount of loss occurs when converting the DC power source. Here, it is assumed that the loss is 20%, that is, the conversion efficiency is 80%.

Here, if the input current data detected by the input current detection unit 111 is 10 A, the conditions are as follows:
Threshold: 14.5A (General current rating of Japanese 100V commercial power supply: 15A to 0.5A margin)
Input current from commercial power supply 110: 10A
Commercial power supply voltage: AC100V
Conversion efficiency of rectification / charging circuit 113: 80%
The power that can be used to charge the electric double layer capacitor 116 is = (14.5-10) × 10 × 0.8
= 360W
It becomes.

  Next, the electric current that can be used to charge the electric double layer capacitor 116 is fixed at 360 W, and the charging current value of the electric double layer capacitor 116 is determined. Assuming that the charging voltage of the electric double layer capacitor 116 at the start of charging is DC 20 V, charging is started as follows, with 18 (A) as the charging current value.

Charging current value = Electric power / charging voltage that can be used to charge the electric double layer capacitor
= 360/20
= 18 (A)

  When charging is started, the charging voltage gradually increases from DC 20 V. However, in the present invention, control is performed so that constant power charging is performed. Therefore, the charging current value is decreased as the charging voltage increases. In order to realize this, the charging voltage of the electric double layer capacitor 116 is periodically sampled, and the charging current value is recalculated each time. For example, if the charging voltage is 20.5 V after a certain time has elapsed since the start of charging, the charging current value is recalculated as follows, and the charging current value is changed from 18 (A) to 17.561 (A). change.

Charging current value = Electric power / charging voltage that can be used to charge the electric double layer capacitor
= 360 / 20.5
= 17.561 (A)

  Thus, by determining the charge amount so that the charge amount to the electric double layer capacitor 116 becomes constant power, the input current from the commercial power supply 110 can be easily limited to the rated current or less.

  In this image forming apparatus, since constant power charging is always performed, the charging current is unnecessarily large in a region where the charging voltage is close to 0 (V) (see FIG. 3). An electronic component generally has a rated current. If the electronic component is used in excess of the rated current, the component may be damaged. If parts with a large rated current are used, damage to the parts can be prevented, but the part cost generally increases according to the rated current, and such a charging method causes an increase in cost. .

  Therefore, in order to avoid the above problem, the image forming apparatus according to the present embodiment has a nonvolatile memory 102 in the control / drive unit 101, and constant current charging is performed on the basis of a specified value stored in the nonvolatile memory 102. Switching between constant power charging.

  Specifically, the description will be made assuming that the specified value serving as a boundary between the constant current charging and the constant power charging is 40 (A). First, a charging current value is calculated assuming that constant power charging is performed, and then it is determined whether the calculated charging current value is 40 (A) or more. When it is 40 (A) or more, constant current charging is performed at 40 (A) regardless of the calculation result, and when it is less than 40 (A), constant current charging is performed using the calculation result as it is. (See FIG. 4).

  By controlling in this way, it is possible to prevent charging with an unnecessarily large current, and it is possible to select a component with a low rated current as a component of the charging means and charge / discharge switching means, thereby reducing costs. It becomes possible.

  As described above, the heating device, the fixing device, and the image forming apparatus according to the present invention are useful for image forming apparatuses such as copying machines and printers using the electrophotographic rich method, and in particular, an electric double layer that is an auxiliary power source. When charging a capacitor, the capacitor is suitable for a heating device, a fixing device, or the like in an image forming apparatus that easily suppresses an input current from a commercial power source to a rated current or less.

1 is an explanatory diagram showing a configuration of a digital copying machine that is an image forming apparatus according to an embodiment of the present invention; FIG. 1 is a block diagram illustrating a main configuration of an image forming apparatus according to an embodiment of the present invention. It is a graph which shows the mode of the constant power charge concerning embodiment of this invention. It is a graph which shows the mode of switching of the constant power charge and constant current charge concerning embodiment of this invention. It is a graph which shows the mode of the constant current charge in the past.

Explanation of symbols

24 fixing unit 100 image forming apparatus 101 control / drive unit 102 nonvolatile memory 103 charge amount calculation unit 110 commercial power supply 111 input current detection unit 113 rectification / charging circuit 114 charge / discharge switching unit 115 voltage detection unit 116 electric double layer capacitor 117 heating unit 118 Main heater 119 Sub heater

Claims (5)

In a heating device having a main heating element that generates heat due to a current supplied from a commercial power source and an auxiliary heating element that generates heat from a DC power source,
A chargeable / dischargeable auxiliary power supply for supplying power to the auxiliary heating element;
Charging means for rectifying a current supplied from the commercial power source and charging the auxiliary power source;
Input current detection means for detecting an input current from the commercial power supply;
Charging voltage detecting means for detecting a charging voltage of the auxiliary power source;
A first state in which the auxiliary power source is charged from the charging means; a second state in which the auxiliary power source is discharged from the auxiliary power source; and a third state in which neither charging nor discharging of the auxiliary power source is performed. Switching means for switching the state according to a predetermined signal;
Based on the voltage of the commercial power supply, the input current by the input current detecting means, and the charging voltage by the charging voltage detecting means, the charging current is calculated so that the charge amount of the auxiliary power supply becomes constant power, and the calculation Control means for controlling charging by the charging means according to the results of
A heating apparatus comprising:   Furthermore, a charging current storage unit that stores in advance a charging current specified value of the charging unit is provided, and the control unit calculates the charging current specified value stored in the charging current storage unit. 2. The heating apparatus according to claim 1, wherein when the charging current value exceeds, the charging unit is controlled according to the charging current regulation value to perform constant current control. In a fixing device having a main heating element that generates heat by a current supplied from a commercial power source and an auxiliary heating element that generates heat from a DC power source and is controlled to a predetermined fixing temperature.
A chargeable / dischargeable auxiliary power supply for supplying power to the auxiliary heating element;
Charging means for rectifying a current supplied from the commercial power source and charging the auxiliary power source;
Input current detection means for detecting an input current from the commercial power supply;
Charging voltage detecting means for detecting a charging voltage of the auxiliary power source;
A first state in which the auxiliary power source is charged from the charging means; a second state in which the auxiliary power source is discharged from the auxiliary power source; and a third state in which neither charging nor discharging of the auxiliary power source is performed. Switching means for switching the state according to a predetermined signal;
Based on the voltage of the commercial power supply, the input current by the input current detecting means, and the charging voltage by the charging voltage detecting means, the charging current is calculated so that the charge amount of the auxiliary power supply becomes constant power, and the calculation Control means for controlling charging by the charging means according to the results of
A fixing device comprising:   Furthermore, a charging current storage unit that stores in advance a charging current specified value of the charging unit is provided, and the control unit calculates the charging current specified value stored in the charging current storage unit. The fixing device according to claim 3, wherein when the charging current value exceeds, the charging unit and the charging unit are controlled according to the specified charging current value to perform constant current control.   An image forming apparatus using the heating device according to claim 1 or 2, or the fixing device according to claim 3 or 4.

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