JP5308965B2 - Power supply device and fixing device - Google Patents

Description

  The present invention relates to a power supply device and a fixing device.

  The power supply device described in Patent Document 1 can be used in regions where the voltage values of supplied power are different. This type of power supply device can be used in both areas where power with a voltage value of 100V is supplied and areas where power with a voltage value of 200V is supplied.

  This type of power supply apparatus is provided with a resonance circuit including a resonance capacitor and an excitation coil. The resonance circuit receives a supply of current when the switching element is in an on state, performs a resonance operation, and generates a magnetic field whose direction and magnitude change from moment to moment from the exciting coil.

  The power supply device includes means for detecting the voltage value of the supplied power. The power supply device interlocks the limit value of the ON state period (switching ON width) of the switching element according to the detected voltage value. For example, when the voltage value of the supplied power becomes high (for example, 100 V level → 200 V level), the power supply device shortens the limit value of the ON state period of the switching element.

Japanese Patent Laid-Open No. 11-191383

  As described above, the above-described power supply apparatus can be used both in a region where power having a voltage value of 100V is supplied and in a region where power having a voltage value of 200V is supplied. However, the power supply apparatus described above has the following problems.

  In the above-described power supply device, the exciting coil has the following windings in order to prepare for both the case where power having a voltage value of 100V level is supplied and the case where power having a voltage value of 200V level is supplied. Diameter and number of turns are required.

  When power of 100V level is supplied, the current value of the current flowing through the exciting coil is larger than when power of 200V level is supplied. Required. In addition, when 200V power is supplied, a higher inductance is required than when 100V power is supplied, and thus a number of turns is required to obtain a high inductance.

  However, meeting the requirements indicated above increases the size of the exciting coil. Moreover, the manufacturing cost of the exciting coil is expensive. Further, when the power supply device is incorporated in the fixing device of the image forming apparatus, the size of the fixing device itself increases, and the space for installing the fixing device increases.

  In order to avoid such a problem, it is conceivable to configure a power supply device in which an excitation coil having a winding diameter and a number of turns corresponding to a voltage value of electric power in a region where the power supply device is used is incorporated. However, it cannot be used in a plurality of areas where the voltage values of the supplied power are different.

  The present invention has been made to solve the above problem, and can be used in regions where the voltage values of the supplied power are different without increasing the size of the exciting coil. And a fixing device.

A power supply device according to one aspect of the present invention includes a voltage booster that is supplied with power having different voltage values, boosts the voltage value of the supplied power to a preset first set voltage value, and an excitation coil And generating a magnetic field whose direction and magnitude change over time from the exciting coil by receiving the power of the voltage value boosted to the first set voltage value and performing a resonance operation. A resonance power supply unit, wherein the first voltage setting value is set according to a voltage value assumed as a maximum voltage value of the supplied power in the voltage boosting unit. you.

  According to this configuration, the voltage boosting unit boosts the voltage value of the supplied power to the first set voltage value set according to the voltage value assumed as the maximum voltage value of the supplied power. And the resonance circuit which consists of an exciting coil and a resonance capacitor performs resonance operation | movement with the electric power boosted to the 1st setting voltage value.

  As a result, if the winding diameter and the number of turns of the exciting coil have specifications suitable for the case where power having the first set voltage value is supplied, the resonance circuit can be supplied with power having different voltage values. The power boosted to the first set voltage value is received, and the resonance operation can be suitably performed.

  Therefore, if the winding diameter and the number of turns of the exciting coil are the specifications suitable for the case where the power of the first set voltage value is supplied, the exciting coil is supplied without increasing the size. Thus, it is possible to provide a power supply device that can be used in regions where the voltage values of the different powers are different.

  In addition, if the winding diameter and the number of turns of the exciting coil are the specifications suitable for the case where the power of the first set voltage value is supplied, the voltage value of the supplied power corresponds to each different region. Therefore, it is not necessary to provide a resonant circuit to be used, so that the standard of the resonant circuit can be unified. Therefore, the manufacturing process of the power supply device incorporating the resonance circuit can be unified. Thereby, the manufacturing cost of a power supply device is suppressed. Furthermore, since the standard of the resonance circuit can be unified, maintenance of the power supply device is facilitated.

In the power supply device according to one aspect of the present invention, when the voltage value of the supplied power is equal to or lower than a lower limit voltage value smaller than the first set voltage value, the supplied power is supplied to the voltage boosting unit. comprises the further step-up control unit for controlling so as not to boost the voltage value, the voltage boosting unit, supplied to the resonant power supply unit without boosting the supplied power.

  In general, it is known that when a voltage is boosted from a very small voltage value to a large voltage value in a voltage boosting unit, the switching element is damaged. In the above configuration, when the voltage value of the supplied power is equal to or lower than the lower limit voltage value smaller than the threshold value, the voltage value of the supplied power is not boosted, so that the switching element can be prevented from being damaged.

Further, a power supply device according to another aspect of the present invention includes a voltage boosting unit that boosts the voltage value of the supplied power that is supplied with power having different voltage values, and an excitation coil. A resonance power supply unit that generates a magnetic field that changes its direction and magnitude as time elapses from the exciting coil by receiving power and performing a resonance operation, and a voltage value of supplied power are prepared in advance. When the voltage is below the threshold value, the voltage booster boosts the voltage value of the supplied power to a second set voltage value set in advance corresponding to the threshold value, and the voltage value exceeds the threshold value. sometimes, to the voltage boosting unit, the supplied power, and the boosting control unit for supplying to the resonant power supply unit without boosting the voltage value, you comprising: a.

  According to this configuration, when the voltage value of the supplied power is equal to or lower than the threshold value, the voltage boosting unit boosts the voltage value of the power to the second set voltage value set in advance corresponding to the threshold value. As a result, the resonance circuit including the excitation coil and the resonance capacitor performs a resonance operation with the electric power boosted to the second set voltage value. On the other hand, when the voltage value of the supplied power exceeds the threshold value, the supplied power is supplied to the resonance power supply unit without boosting the voltage value. As a result, the resonance circuit receives the power holding the voltage value when supplied and performs the resonance operation.

  Thus, if the number of turns and the number of turns of the exciting coil are the specifications suitable when the power of the second set voltage value and the power of the voltage value exceeding the threshold are supplied, Regardless of whether the voltage value is equal to or less than the threshold value or exceeds the threshold value, the resonance circuit can suitably perform the resonance operation.

In the above configuration, when the voltage value of the supplied power is equal to or lower than a lower limit voltage value smaller than the threshold value, the boost control unit boosts the supplied power to the voltage boosting unit. let the Ru can be configured to supply to the resonant power supply unit without.

  In general, it is known that when a voltage is boosted from a very small voltage value to a large voltage value in a voltage boosting unit, the switching element is damaged. In the above configuration, when the voltage value of the supplied power is equal to or lower than the lower limit voltage value smaller than the threshold value, the voltage value of the supplied power is not boosted, so that the switching element can be prevented from being damaged.

In the above configuration, the object to be heated comprising a magnetic material, Ru can be configured to be inductively heating device for electromagnetic induction heating by the magnetic field generated by the exciting coil. According to this structure, the induction heating apparatus which has the said effect can be provided.

The fixing device according to still another aspect of the present invention includes the power supply device includes a magnetic body, and a heat roller rotating about an axis of rotation, provided parallel to said rotation axis of said heat roller, wherein A pressure roller that rotates in contact with the heat roller, and heat-fixes the toner image transferred to the sheet at a nip formed by a contact portion between the heat roller and the pressure roller. it characterized in that it is configured to. According to this configuration, it is possible to provide a fixing device that exhibits the above effects.

  According to the present invention, it is not necessary to increase the size of the exciting coil if the winding diameter and the number of turns of the exciting coil have specifications suitable for the case where power having the first set voltage value is supplied. In addition, it is possible to provide a power supply apparatus that can be used in regions where voltage values of supplied power are different.

It is the circuit diagram which showed an example of the power supply device which concerns on one Embodiment of this invention. It is the figure which showed the structure of the heating part typically. It is the figure which showed an example of the correlation with the input voltage and the voltage between terminals of a smoothing capacitor when the 1st pressure | voltage rise process is performed. It is the figure which showed an example of the correlation with the input voltage and the voltage between terminals of a smoothing capacitor at the time of performing the 2nd pressure | voltage rise process. 1 is a longitudinal sectional view illustrating a mechanical configuration of an image forming apparatus including a fixing device according to an embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 5 is a longitudinal sectional view showing a mechanical configuration of an image forming apparatus including a fixing device according to an embodiment of the present invention. The image forming apparatus A generally includes a main body portion 32, a scanner portion 33 disposed above the main body portion 32, and an ADF 34 disposed above the scanner portion 33. Is done.

  In the main body 32, one of the recording papers 41a, 42a, 43a, 44a loaded in one or a plurality of trays 41, 42, 43 and the manual feed tray 44 is fed one by one by the paper feed rollers 41b, 42b, 43b, 44b. The paper is fed and the timing is adjusted by the registration rollers 45 and 46, and then conveyed to the image forming unit 47. The image forming unit 47 includes a charger (not shown), a laser writing unit, a developing unit, a transfer unit 47b, a cleaning unit (not shown), and the like around the photosensitive drum 47a, and forms an image on a recording sheet by electrophotography. . The toner image thus formed on the recording paper is fixed by a fixing device (induction heating device) 48 including a power supply device 1 and a heating unit 2 which will be described later, and is discharged from the discharge rollers 49 and 50 onto the paper discharge tray 51. The

  Image data given to the laser writing unit is read by the scanner unit 33. The scanner unit 33 includes a scanning unit 53 that irradiates the original with illumination light through the document table 52 and receives reflected light under the document table 52 made of a plate-shaped transparent plate such as a glass plate, and a scanning unit. A mirror unit 54 for further reflecting the reflected light obtained at 53, an imaging lens 55 for condensing the reflected light from the mirror unit 54, and a CCD 12 for photoelectrically converting the reflected light imaged by the imaging lens 55, It is configured with.

  The scanning unit 53 is moved in the sub-scanning direction by a stepping motor (not shown), for example. The scanning unit 53 moves at a speed V and the mirror unit 54 moves at a speed V / 2 in the left-right direction of 5, that is, the sub-scanning direction, so that the book or single sheet placed on the document table 52 is moved. An original image is always formed on the CCD 12 with an equal optical path length.

  On the other hand, in the ADF 34 that sequentially takes in the sheet originals, the originals 62 stacked on the original tray 61 are fed one by one by the paper feed roller 63 and supplied to the curved conveyance path 64. And it is conveyed by the conveyance roller 65,66,67,68 provided in the curved conveyance path 64 to the reading window 82 which consists of plate-shaped transparent plates, such as a glass plate extended in a main scanning direction, and a scanning part is carried out to the reading window 82. The original images are sequentially read in a state where 53 faces, and are then discharged onto the discharge tray 81 by the discharge rollers 69 and 80.

  The scanning unit 53 includes a cold-cathode tube 531 (light source), a reflector 532 that irradiates light emitted from the cold-cathode tube 531 toward the document table 52 and the reading window 82, and the document table 52 and the reading window 82 from the document. And a mirror 533 for reflecting the reflected light obtained by passing through the mirror unit 54 to the mirror unit 54.

  FIG. 1 is a circuit diagram showing an example of a power supply device according to an embodiment of the present invention. FIG. 2 is a diagram schematically showing the configuration of the heating unit 2 constituting the fixing device 48 in combination with the power supply device according to the embodiment of the present invention.

  A power supply device 1 shown in FIG. 1 includes an input voltage detection unit 10, a boosting unit (voltage boosting unit) 11, a resonant power supply unit 12, and a thermistor 13. The power supply device 1 constitutes the above-described fixing device (induction heating device) 48 in combination with the heating unit 2.

  In FIG. 1, the power line L accepts AC power supplied from outside and having different effective voltage values within a range of 100 V to 240 V, and further supplies the received AC power to the input voltage detection unit 10.

  The input voltage detection unit 10 includes a Zener diode ZD having a cathode terminal connected to the power line L and an anode terminal connected to the boost control circuit 110, and a resistor R1 for flowing a reverse current of the Zener diode ZD. . In the input voltage detection unit 10, when the maximum amplitude value of the AC power supplied to the power line L becomes equal to or higher than the breakdown voltage of the Zener diode ZD, a reverse current flows in the direction of the boost control circuit 110 in the Zener diode ZD. . The boost control circuit 110 that has received this reverse current detects that the maximum amplitude value of the AC power supplied to the power line L exceeds the breakdown voltage of the Zener diode ZD.

  A diode bridge D1 is provided between the input voltage detector 10 and the booster 11. The diode bridge D1 rectifies AC power supplied to the power line L to generate a pulsating flow. Here, the pulsating flow means a current whose flow direction is constant and whose magnitude changes periodically. The generated pulsating flow is supplied to the booster 11.

  The step-up unit 11 includes a step-up type PFC circuit (power factor control circuit). The booster 11 includes a choke coil L1, a switching element Q1 composed of a MOSFET, a resistor R2 for outputting a pulse to the gate terminal of the switching element Q1, and a current during a high level period of the pulse output to the gate terminal. By flowing, a resistor R3 for applying a gate voltage with the power line L to the ground level to the gate terminal, a diode D2, a smoothing capacitor C1, and two resistors R4 for monitoring the charging voltage of the smoothing capacitor C1 , R5, and a boost control circuit (boost control unit) 110.

  In the booster 11, the choke coil L1, the switching element Q1, the resistors R2 and R3, and the diode D2 constitute a boost PFC circuit.

  In the booster 11, the boost control circuit 110 receives the reverse voltage generated in the Zener diode ZD as described above, and the maximum amplitude value of the AC power supplied to the power line L is the breakdown voltage of the Zener diode ZD. Detects that it exceeds

  Further, the boost control circuit 110 performs overall control of the boost unit 11 and performs the power factor improvement process described below. Boost control circuit 110 applies a drain voltage by applying a gate voltage to the gate terminal of switching element Q1. Thereby, the switching element Q1 is turned on. On the other hand, when no gate voltage is applied to the gate terminal of the switching element Q1, no drain current flows, so the switching element Q1 is turned off.

  The step-up control circuit 110 performs control to turn on and off the switching element Q1 to align the waveform of the current discharged from the smoothing capacitor C1 with the voltage waveform of the AC power supplied to the power line L (power factor improvement).

  That is, the boost control circuit 110 turns on the switching element Q1 and stores electric energy in the choke coil L1. Thereafter, the boost control circuit 110 turns off the switching element Q1, supplies the electric energy stored in the choke coil L1 to the smoothing capacitor C1 through the backflow prevention diode D2, and charges it.

  In this way, the smoothing capacitor C1 is charged with the electric energy stored in the choke coil L1. Thereby, the voltage across the smoothing capacitor C1 becomes a voltage value higher than the maximum amplitude value of the pulsating flow generated by the diode bridge D1. When the voltage value of the electric energy supplied from the choke coil L1 is lower than the voltage across the terminals of the smoothing capacitor C1, discharge occurs in the smoothing capacitor C1.

  The discharge power of the smoothing capacitor C1 having a voltage at both ends having a voltage value higher than the maximum amplitude value of the pulsating flow generated by the diode bridge D1 due to the discharge of the smoothing capacitor C1 is supplied to the power line L. Is supplied to the resonance power supply unit 12 as DC power boosted to a voltage value higher than the voltage value of.

  The charging described above is performed when the switching element Q1 is in an off state, and the discharging described above is performed when the switching element Q1 is in an on state.

  Further, in the booster 11, a series circuit composed of the resistors R4 and R5 described above is connected in parallel with the smoothing capacitor C1. A series circuit composed of resistors R4 and R5 steps down the voltage across the capacitor C1 by resistance division.

  The both-end voltage stepped down by resistance division is input to the step-up control circuit 110. Thereby, the boost control circuit 110 monitors the voltage across the terminals of the smoothing capacitor C1. Then, the boost control circuit 110 switches the switching element Q1 so that the voltage between the terminals of the smoothing capacitor C1 becomes a constant voltage value, and charges and discharges the smoothing capacitor C1.

  Through the control described above, DC power having a constant voltage value with improved power factor is supplied from the booster unit 11 to the resonance power supply unit 12.

  Here, when AC power having an effective voltage value (lower limit voltage value; for example, effective voltage value of 50 V or less) equal to or lower than a predetermined voltage value is supplied to the power line L, the booster unit 11 causes the effective power of the AC power to be reduced. If the voltage value is boosted to match the effective voltage value (for example, 240 V) of the AC power supplied in a foreign country, the switching element Q1 of the boosting unit 11 may be destroyed.

  Therefore, when the AC power having an effective voltage value equal to or lower than a predetermined voltage value is supplied to the power line L, the boost control circuit 110 keeps the switching element Q1 in the OFF state, and the diode bridge D1. Is supplied to the smoothing capacitor C1. Then, the smoothing capacitor C1 generates DC power by smoothing the supplied pulsating flow by charging and discharging. Such DC power is DC power having the maximum amplitude value of the pulsating current, and is supplied to the resonance power supply unit 12.

  The resonance power supply unit 12 generates a magnetic field whose magnitude and direction change from moment to moment from the exciting coil L2 by a resonance operation in the LC series resonance circuit. The resonant power supply unit 12 includes two LC series resonant circuits 121 and 122. The first LC series resonance circuit 121 includes an exciting coil L2 and a resonance capacitor C4. The second LC series resonance circuit 122 includes an exciting coil L2 and a resonance capacitor C5.

  The first LC series resonance circuit 121 includes a partial resonance capacitor C2 that makes switching of the switching element Q2 described later smooth. The second LC series resonance circuit 122 includes a partial resonance capacitor C3 that makes switching of a switching element Q3 described later smooth. Here, switching means that the switching elements Q2 and Q3 are switched between an on state and an off state.

  Further, the first LC series resonance circuit 121 includes a switching element Q <b> 2 that supplies a current to the first LC series resonance circuit 121. The second LC series resonance circuit 122 includes a switching element Q3 that supplies current to the second LC series resonance circuit 122. In the present embodiment, the switching elements Q2 and Q3 are constituted by insulated gate bipolar transistors.

  Switching element Q2 turns on connection point a in the on state and turns off the connection point in the off state. When the connection point a is turned on, a current flows to the first LC series resonance circuit 121. However, when the connection point a is turned off, no current flows to the first LC series resonance circuit 121. .

  Further, the switching element Q3 makes the connection point b conductive when in the on state and makes the connection point non-conductive when off. When the connection point b is turned on, a current flows to the second LC series resonance circuit 122, but when the connection point b is turned off, no current flows to the second LC series resonance circuit 122. . Here, each of switching elements Q2 and Q3 is turned on when a gate voltage is applied, and is turned off when no gate voltage is applied.

  The resonant power supply unit 12 includes a resonant power supply control circuit 120 in order to control each of the switching elements Q2 and Q3. The resonant power supply control circuit 120 outputs a pulse to each of the switching elements Q2 and Q3 to turn on and off the switching elements Q2 and Q3. That is, the resonant power supply control circuit 120 outputs a pulse having a predetermined duty ratio to each of the switching elements Q2 and Q3. The resonant power supply control circuit 120 applies a gate voltage during a period when the pulse is at a high level, and does not apply a gate voltage when the pulse is at a low level.

  As described above, the resonance power supply control circuit 120 applies the gate voltage during the period when the pulse is at the high level, and does not apply the gate voltage during the period when the pulse is at the low level. Therefore, the cycle in which each of switching elements Q2 and Q3 is turned on and the cycle in which it is turned off depend on the frequency of the pulse.

  Therefore, the resonant power supply control circuit 120 changes the frequency of the pulse output to each of the switching elements Q2 and Q3, thereby changing the cycle in which each of the switching elements Q2 and Q3 is turned on and the cycle in which the switching elements Q2 are turned off. Can be changed.

  Here, a cycle in which current is supplied to the first and second LC series resonance circuits 121 and 122 by changing the cycle in which each of the switching elements Q2 and Q3 is turned on and the cycle in which the switching elements Q3 are turned off. Can be changed. When the cycle in which current is supplied to the first and second LC series resonance circuits 121 and 122 changes, the magnitude of the electrical energy stored in the first and second LC series resonance circuits 121 and 122 changes. .

  Therefore, the resonant power supply control circuit 120 adjusts the frequency of the pulse to be output to the switching elements Q2 and Q3 in order to adjust the magnitude of electric energy in the first and second LC series resonant circuits 121 and 122. .

  The magnitude of the electric energy in the first and second LC series resonance circuits 121 and 122 is such that the frequency of the pulses output to the switching elements Q2 and Q3 is the same as the first and second LC series resonance circuits 121 and 122. Maximum when the resonance frequency is unique.

  The resonant power supply unit 12 includes resistors R8 and R9 for outputting pulses to the gate terminals of the switching elements Q2 and Q3, respectively. Further, the resonant power supply unit 12 is configured to cause the gate voltage to have the power line L at the ground level with respect to the gate terminal when a current flows during the high level period of the pulse output to the gate terminals of the switching elements Q2 and Q3. Are provided with resistors R6 and R7, respectively.

  In the resonance power supply unit 12 configured as described above, the resonance power supply control circuit 120 turns on the switching elements Q2 and Q3 alternately to turn on the first LC series resonance circuit 121 and the second LC series resonance circuit. The resonance operation is performed alternately. As a result, a magnetic field whose direction and size change every moment is generated in the exciting coil L2.

  The heating unit 2 includes an exciting coil L2, a core member 20 around which the exciting coil L2 is wound, and a heat roller (heated body) 21 including a magnetic material. In the heat roller 21, an eddy current is generated by a magnetic field whose direction and magnitude change every moment. As a result, Joule heat is generated by the electric resistance of the heat roller 21, so that the heat roller 21 is heated.

  And the thermistor 13 which detects the temperature of the heat roller 21 in the state which adjoins to the heat roller 21 is provided. A resonant power supply control circuit 120 is connected to the thermistor 13. The resonant power supply control circuit 120 receives feedback of the temperature of the heat roller 21 detected by the thermistor 13 and controls the heat roller 21 to have a constant temperature. For example, the resonant power supply control circuit 120 switches the switching elements Q2 and Q3 so that the heat roller 21 has a constant temperature, and supplies the current supplied to the first and second LC series resonant circuits 121 and 122. Control the amount of current.

  FIG. 2 is a diagram schematically showing the configuration of the heating unit 2. In the heating unit 2, the heat roller 21 rotates about the rotation axis. A pressure roller 22 is provided in parallel with the rotation axis of the heat roller 21 and rotates in contact with the heat roller 21. Furthermore, the thermistor 13 is provided in the state close to the heat roller 21. Such a heating unit 2 heat-fixes the toner image transferred to the paper S at a nip formed by a contact portion between the heat roller 21 and the pressure roller 22.

  The power supply device 1 having such a configuration can perform the first and second boosting processes described below. FIG. 3 is a diagram illustrating an example of the correlation between the input voltage and the voltage across the smoothing capacitor C1 when the first boosting process is performed. FIG. 4 is a diagram showing an example of the correlation between the input voltage and the voltage across the smoothing capacitor C1 when the second boosting process is performed.

[First boosting process]
As shown in FIG. 3, when AC power having an effective voltage value exceeding 50V is supplied, the boost control circuit 110 is configured to perform the first setting regardless of the effective voltage value of the AC power. The booster unit 11 is controlled so that the discharge energy of the smoothing capacitor C1 having a voltage value (380 V) at both ends is supplied to the resonant power supply unit 12 as boosted DC power.

  Through such control, the boost control circuit 110 sets the supplied AC power to DC power having the first set voltage value (380 V). Hereinafter, the reason why the supplied AC power is 380 V DC power will be described.

  The effective voltage value of AC power currently supplied as commercial power in various countries in the world includes an effective voltage value of 100V level and an effective voltage value of 200V level. The effective voltage value in the 200V range includes an effective voltage value of 220V, an effective voltage value of 230V, and an effective voltage value of 240V.

  In order to enable the power supply device 1 to be used in both a country where commercial power having an effective voltage value of 100V is supplied and a country where commercial power having an effective voltage value of 200V is supplied, The booster 11 needs to boost the lowest effective voltage value among the effective voltage values in the 100V range and the highest effective voltage value out of the effective voltage values in the 200V range to the common set voltage value. Then, as a common set voltage value, for example, it is obtained by multiplying √2 by the operation guarantee voltage 264V of the electronic device specified for 240V which is the highest effective voltage value among the effective voltage values of the 200V range. A voltage value slightly larger than the maximum amplitude value (approximately 380 V) can be mentioned.

  Assuming that the supplied AC power is 380V DC power, the DC power of 380V is the resonant power supply regardless of the AC power of any effective voltage value among the AC power of the 100V and 200V effective voltage values. To the unit 12. Therefore, if the winding diameter and the number of turns of the exciting coil L2 of the resonance power supply unit 12 are set to specifications suitable for the case where 380 V DC power is supplied, the resonance operation can be performed regardless of the AC power of any effective voltage value. Can be suitably performed.

  In FIG. 3, the hatched area is an area indicating that the boosting process is not performed when AC power having an effective voltage value of 50 V or less is supplied. If the effective voltage value of 50V or less is boosted to 380V, the switching element Q1 of the boosting unit 2 may be destroyed, so the power supply device 1 does not perform the boosting process.

  In this way, the fact that the boosting process is not performed when AC power having an effective voltage value of 50 V or less is supplied can be realized with the configuration shown below. For example, apart from the Zener diode ZD, the breakdown voltage is slightly larger than the value obtained by multiplying 50V by √2 (approximately 70.7V; the maximum amplitude value of the AC power with an effective voltage value of 50V). A cathode terminal of a Zener diode is connected to the power line L, and an anode terminal is connected to the boost control circuit 110 via a resistor. Then, while the boost control circuit 110 does not detect the reverse current of the newly connected Zener diode, the boost control circuit 110 does not perform the boost process. With the above configuration, it is possible to realize no boosting process when AC power having an effective voltage value of 50 V or less is supplied.

[Second boosting process]
Boost control circuit 110 determines that the effective voltage value of the AC power supplied to power line L1 is equal to or less than the threshold value (140 V) when the reverse current of Zener diode ZD is not received. In that case, the boost control circuit 110 boosts the discharge energy of the smoothing capacitor C1 having a voltage across the second set voltage value (280V) so as to be supplied to the resonant power supply unit 12 as boosted DC power. The unit 11 is controlled. By such control, the boost control circuit 110 converts the supplied AC power to DC power of the second set voltage value (280 V) as shown in FIG.

  Here, the threshold value (140V) is a voltage value assumed as the highest effective voltage value in the 100V range. Further, the second set voltage value (280V) is obtained by multiplying √2 by the operation guarantee voltage 198V of the electronic device specified for 220V which is the lowest effective voltage value among the effective voltage values of the 200V range. The maximum amplitude value.

  As described above, when the effective voltage value of the supplied AC power is equal to or lower than the threshold (140 V) assumed as the highest effective voltage value of the 100 V range, the supplied AC power is converted to the lowest effective voltage value of the 200 V level. The voltage is boosted to a second set voltage value (280V) corresponding to 220V.

  On the other hand, the boost control circuit 110 determines that the effective voltage value of the AC power supplied to the power line L1 exceeds the threshold value (140 V) when the reverse current of the Zener diode ZD is received. In that case, the boost control circuit 110 supplies the pulsating flow supplied from the diode bridge D1 to the smoothing capacitor C1 while the switching element Q1 is in the OFF state. Then, as described above, DC power having the maximum amplitude value of the pulsating current is supplied to the resonance power supply unit 12.

  For example, when AC power having an effective voltage value of 240 V is supplied, the maximum amplitude value of the pulsating current is a value (approximately 340 V) obtained by multiplying the effective voltage value (240 V) by √2. Therefore, when AC power having an effective voltage value of 240 V is supplied, DC power of 340 V is supplied to the resonance power supply unit 12.

  As described above, 280 V DC power is supplied to the resonance power supply unit 12 regardless of any effective voltage value in the 100 V range. When AC power having an effective voltage value exceeding the threshold (140 V) is supplied, DC power having a voltage value having the maximum amplitude value of the AC power is supplied to the resonance power supply unit 12.

  Accordingly, if the winding diameter and the number of turns of the exciting coil L2 of the resonance power supply unit 12 are set to specifications suitable for the case where 200V DC power is supplied, the AC power of any effective voltage value of 100V and 200V Even if is supplied, the resonance operation can be suitably performed.

  In FIG. 4, the hatched area is an area indicating that the boosting process is not performed when AC power having an effective voltage value of 50 V or less is supplied. When the effective voltage value of 50 V or lower is boosted to 280 V, as described above, the switching element Q1 of the boosting unit 2 may be destroyed, so the power supply device 1 does not perform the boosting process.

DESCRIPTION OF SYMBOLS 1 Power supply device 2 Heating part 11 Pressure | voltage rise part 12 Resonance power supply part 21 Heat roller 22 Pressure roller 48 Fixing apparatus (induction heating apparatus)
110 Boost control circuit S Paper L2 Excitation coil

Claims (3)

A voltage booster that is supplied with power having different voltage values and boosts the voltage value of the supplied power to a preset first set voltage value;
A magnetic field having an exciting coil and receiving a power of a voltage value boosted to the first set voltage value and performing a resonance operation so that the direction and magnitude of the magnetic field changes with time from the exciting coil. A resonance power supply unit for generating
In the voltage booster, the first set voltage value is set according to a voltage value assumed as the maximum voltage value of the supplied power ,
When the voltage value of the supplied power is equal to or lower than the lower limit voltage value smaller than the first set voltage value, the voltage boosting control unit controls the voltage boosting unit so as not to boost the voltage value of the supplied power. Further comprising
The voltage booster is configured to supply the supplied power to the resonant power supply without boosting the supplied power. The power supply device according to claim 1 , wherein the power source device is an induction heating device that electromagnetically heats a heated object including a magnetic material by the magnetic field generated by the excitation coil. A power supply device according to claim 2 ;
A heat roller including a magnetic body and rotating about a rotation axis;
A pressure roller that is provided in parallel with the rotating shaft of the heat roller and rotates in contact with the heat roller;
A fixing device, wherein a toner image transferred onto a sheet is thermally fixed at a nip portion formed at a contact portion between the heat roller and the pressure roller.

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