JP2006268680A - Flicker suppressing device, flicker suppressing method, and fixing device of image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flicker suppressing device and a flicker suppressing method, capable of effectively suppressing flicker even if the frequency of an AC power source is fluctuated through a simplified structure. <P>SOLUTION: A current detection circuit 19 detects a current carried in a halogen lamp 21 of a fixing device 20, and a temperature detection sensor 22 detects the temperature of the halogen lamp 21. A frequency/phase recognition part 31 recognizes the frequency and phase of the AC power source 1 based on output of the current detection circuit 19, and a fixing device control part 33 corrects, based on output of the temperature detection sensor 22 and the frequency and phase recognized by the frequency/phase recognition part 31, the switching time of a switching element 10 switching the current carried to the halogen lamp 21. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flicker suppressing device and a flicker suppressing method for an apparatus such as an image forming apparatus having a heat generating portion that generates heat by applying an output of an AC power supply, and more specifically, a flicker suppressing device that performs flicker suppression using wave number control, and The present invention relates to an improvement of a flicker suppression method.

  In general, in an apparatus such as an image forming apparatus having a heat generating portion that generates heat by applying an output of an AC power source, a large inrush current is generated due to the impedance characteristic of the heat generating portion, and accordingly, an office or the like in which this device is installed In the case of flicker, a flicker problem occurs that the fluorescent lamp flickers.

  For example, some printers, copiers, and the like installed in offices have a fixing unit that generates heat when an output from an AC power supply is applied.

  Heat generation of the halogen lamp in the fixing unit is performed by applying an AC power supply output to the halogen lamp. When a large inrush current is generated due to the impedance characteristic of the halogen lamp, the image forming apparatus is A flicker phenomenon occurs in which a fluorescent lamp in an installed office flickers.

  Conventionally, as a countermeasure against the flicker phenomenon, wave number control as shown in Patent Document 1 and Patent Document 2 is known. This wave number control is a control that suppresses the flicker value by performing repetitive control of half cycle ON and one cycle OFF when supplying the AC (alternating current) voltage of the commercial power supply to the halogen lamp of the fixing device.

As this wave number control technique, there are known a zero-cross detection method for detecting the phase of an AC voltage of a commercial power source as shown in Patent Document 1 and a method that does not perform zero-cross detection as shown in Patent Document 2.
Japanese Patent Publication No. 60-46711 Japanese Patent Laid-Open No. 11052782

  However, in the configuration employing the zero-cross detection method as disclosed in Patent Document 1, zero-cross detection is required, so that there are problems such as an increase in cost and an increase in size due to an increase in the number of parts.

  Further, the method that does not perform zero cross detection as disclosed in Patent Document 2 has a problem that the flicker value cannot be stably controlled due to the influence of the frequency of the commercial power source.

  Further, the conventional configuration has a problem that the flicker value cannot be effectively suppressed due to the variation in the commercial power line impedance in an installation environment where the commercial power line impedance is large.

  Accordingly, an object of the present invention is to provide a flicker suppressing device, a flicker suppressing method, and a fixing device for an image forming apparatus that can effectively suppress flicker even when the frequency of an AC power supply fluctuates. And

  In order to achieve the above object, the invention of claim 1 is a switching element for switching a current flowing from the AC power source to the heat generating part in a flicker suppressing device for a device having a heat generating part that generates heat by applying an output of the AC power source. Current detecting means for detecting the current flowing through the heat generating part, temperature detecting means for detecting the temperature of the heat generating part, detection output of the temperature detecting means and detection output of the current detecting means based on the detection output of the switching element. And wave number control means for controlling switching timing.

  According to a second aspect of the present invention, in the first aspect of the invention, the wave number control means is added to the switching element and a recognition means for recognizing the frequency and phase of the AC power supply based on the detection output of the current detection means. A switching control signal generating means for generating a switching control signal, a target value table for storing a target value for correcting the switching timing of the switching control signal corresponding to the frequency and phase of the AC power supply, and the recognition means Signal correction means for correcting the switching control signal with reference to the target value stored in the target value table based on the frequency and phase of the AC power supply.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the wave number control means recognizes and recognizes the state of the wave number control by the wave number control means based on the detection output of the current detection means. The control period of the wave number control is controlled based on the state of the wave number control.

  According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the apparatus further comprises voltage detection means for detecting an output voltage of the AC power supply, and the wave number control means is detected by the voltage detection means. The voltage, frequency and phase of the AC power supply are recognized based on the output, and the switching control signal is corrected based on the recognized voltage, frequency and phase of the AC power supply.

  The invention according to claim 5 is characterized in that the voltage detecting means indirectly detects the output voltage of the AC power supply from a primary circuit or a secondary circuit of a power supply circuit that converts the output voltage of the AC power supply. To do.

  According to a sixth aspect of the present invention, in the fourth aspect of the present invention, the voltage detecting means detects an output voltage of the AC power source based on a voltage drop due to a current flowing through the switching element.

  The invention according to claim 7 further comprises line impedance detection means for detecting line impedance of the AC power supply according to any one of claims 1 to 6, wherein the wave number control means is the line impedance detection means. The control period of the wave number control is controlled on the basis of the detected output.

  The invention according to claim 8 is the invention according to claim 7, wherein the line impedance detection means includes an input voltage from the AC power supply to the device, an internal impedance of the device, an on-impedance of the switching element, and the heating unit. It is detected by calculating the line impedance based on the impedance.

  According to a ninth aspect of the present invention, there is provided a fixing device of an image forming apparatus having a heat generating portion that generates heat when an output of an AC power supply is applied, a switching element that switches a current flowing from the AC power source to the heat generating portion, and the heat generation. Current detection means for detecting the current flowing through the part, temperature detection means for detecting the temperature of the heat generating part, control output of the temperature detection means and control of switching timing of the switching element based on the detection output of the current detection means And a flicker suppressing device including a wave number control means for performing the above operation.

  According to a tenth aspect of the present invention, in the method for suppressing flicker of a device having a heat generating portion that generates heat by applying an output of an AC power supply, the current flowing through the heat generating portion is detected by current detection means, and the temperature of the heat generating portion is determined. Detecting by the temperature detecting means, recognizing the frequency and phase of the AC power supply by the recognizing means based on the detection output of the current detecting means, and detecting the output of the temperature detecting means and the frequency of the AC power supply recognized by the recognizing means and Based on the phase, the switching timing of the switching element that switches the current flowing through the heat generating portion is corrected by the wave number control means.

  According to the present invention, in a device having a heat generating part that generates heat by applying an output of an AC power source, the current flowing through the heat generating part is detected by the current detecting means, the temperature of the heat generating part is detected by the temperature detecting means, and current detection is performed. Of the switching element for recognizing the frequency and phase of the AC power supply based on the detection output of the means by the recognition means, and for switching the current flowing in the heat generating portion based on the frequency output and phase of the AC power supply recognized by the detection output of the temperature detection means Since the switching timing is corrected, the flicker can be effectively suppressed with a simple configuration.

  Embodiments of a flicker suppressing device, a flicker suppressing method, and a fixing device of an image forming apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a main part of a first embodiment of an image forming apparatus configured by applying a flicker suppressing apparatus and a flicker suppressing method according to the present invention.

  In FIG. 1, the image forming apparatus includes a power supply device 10 to which a commercial AC power supply 1 is applied, a fixing device 20, a control unit 30, and a drive device 40.

  Here, the fixing device 20 is used for fixing a toner image on a sheet printed out from the image forming apparatus, and includes a halogen lamp 21 and a temperature detection sensor 22 for detecting the temperature of the halogen lamp 21. ing.

  The drive device 40 is a device that includes a motor that controls paper conveyance of the image forming apparatus, movement of a carriage that performs optical reading, rotation of a photosensitive drum, and the like.

  The power supply device 10 generates a power source that drives the impedance element 11, the switching element 12 that turns on and off the current flowing through the halogen lamp 21 of the fixing device 20, the switches 13 and 14 that are turned off in the power saving mode, and the control unit 30. The transformer 15 and the smoothing circuit 16, the transformer 17 and the smoothing circuit 18 that generate power for driving the driving device 40, and the current detection circuit 19 that detects the current flowing through the halogen lamp 21 of the fixing device 20 are provided.

  The control unit 30 includes a frequency / phase recognition unit 31, a target value table 32, a fixing device control unit 33, and a power saving control unit 34.

  Here, the frequency / phase recognition unit 31 recognizes the frequency and phase of the commercial AC power supply 1 based on the output of the current detection circuit 18.

  The target value table 32 stores target values for correcting the switching control signal generated by the fixing device control unit 31 corresponding to the frequency and phase of the commercial AC power supply 1 recognized by the frequency / phase recognition unit 31. The

  Here, as an example of the target value stored in the target value table 32, specifically, the ON time and OFF time of the halogen lamp 21, the OFF temperature of the halogen lamp 21, the ON temperature, and the like.

  The target values stored in the target value table 32 are optimum for each mode corresponding to the operation mode of the image forming apparatus, for example, the warm-up mode, the run mode, the standby mode, the low power mode, and the sleep mode. It may be configured to store various values.

  The fixing device control unit 31 performs generation control of the switching control signal for turning on and off the switching element 12 and correction control of the switching control signal to cope with the frequency and phase fluctuations of the commercial AC power supply 1.

  The temperature control of the halogen lamp 21 of the fixing device 20 and the wave number control for suppressing flicker are realized by the on / off control of the switching element 12 by the switching control signal.

  The power saving control unit 34 realizes a power saving mode (low power mode, sleep mode) of the image forming apparatus by transmitting a switch-off signal to the switches 12 and 13 or one of them.

  In the image forming apparatus according to the first embodiment, wave number control is performed in order to suppress flicker due to inrush current generated when the commercial AC power supply 1 is applied to the halogen lamp 21.

  This wave number control is realized by performing half cycle ON and one cycle OFF control of the commercial AC power source 1 in a predetermined wave number control period when the commercial AC power source 1 is applied, as shown in FIG.

  Here, when the pulse signal specification of the switching control signal is fixed to, for example, ON time: 10 ms, OFF time: 20 ms, ON / OFF cycle: 30 ms, the commercial frequency is 50 Hz, as shown in FIG. The wave number control of the repetitive waveform of “half cycle ON, 1 cycle OFF” can be realized, but the desired wave number control cannot be realized at a commercial frequency of 60 Hz, and “half cycle ON, 1.5 cycle OFF” and “half cycle” It becomes an unstable waveform state such as “ON, 1 cycle OFF”, and the flicker level deteriorates.

  That is, if a fixed pulse signal that is asynchronous with the commercial AC voltage waveform is used as the switching control signal, the frequency fluctuation of the commercial AC power supply cannot be handled.

  Therefore, in the first embodiment, the frequency / phase recognition unit 31 recognizes the frequency and phase of the commercial AC power supply 1 based on the output of the current detection circuit 19, and the frequency and phase stored in the target value table 32 in advance. Even if the frequency of the commercial AC power source 1 fluctuates by dynamically correcting the switching control signal generated by the fixing device control unit 31 with reference to the target value for correcting the switching control signal corresponding to the phase. In addition, the flicker can be suppressed satisfactorily.

  FIG. 3 is a diagram showing an example of control of the fixing device 20 by the fixing device control unit 33 shown in FIG.

  When it is detected that the temperature of the halogen lamp 21 has decreased below the ON temperature target value based on the output of the temperature detection sensor 22, the fixing device control unit 33 instructs the halogen lamp to be turned on by a halogen lamp ON / OFF signal. First, the switching control signal is controlled to “half cycle ON, 1 cycle OFF”, and wave number control is performed so that the switching element 12 is “half cycle ON, 1 cycle OFF”.

  In the wave number control in this case, the switching control signal corresponding to the frequency and phase stored in the target value table 32 so as to be synchronized with the frequency and phase of the commercial AC power supply 1 recognized by the frequency / phase recognition unit 31. The switching control signal for on / off control of the switching element 12 is dynamically corrected with reference to the target value for the correction.

  Thereby, even if the frequency and phase of the commercial AC power supply 1 fluctuate, the inrush current can be effectively suppressed and the flicker can be suppressed satisfactorily.

  When the wave number control detects that the inrush current is stable based on the output of the temperature detection sensor 22, the switching control signal is controlled to be continuously ON, and the wave number control is terminated.

  When the temperature of the halogen lamp 21 exceeds the OFF temperature target value, the switching control signal is continuously turned off to instruct the halogen lamp to be turned off.

  Since the wave number control period varies depending on the frequency and phase of the commercial AC power supply 1 in addition to the ON time, OFF time, OFF temperature, ON temperature and the like of the halogen lamp 21 of the halogen lamp 21, the target of this wave number control period is The value may also be stored in advance in the target value table 32, and the fixing device control unit 31 may be configured to control the wave number control period with reference to the target value of the wave number control period stored in the target value table 32. .

  Incidentally, in the first embodiment, the frequency and phase fluctuations of the commercial AC power supply 1 can be dealt with, but the voltage fluctuations of the commercial AC power supply 1 cannot be dealt with. Therefore, a second embodiment in consideration of voltage fluctuation of the commercial AC power supply 1 will be described next.

  FIG. 4 shows voltage fluctuations of the commercial AC power supply 1 detected from the primary side of the smoothing circuit 17 of the power supply apparatus 10, and correction of the switching control signal in the wave number control of the fixing apparatus control unit 33 is performed. It is a block diagram which shows the principal part of Example 2 of the image forming apparatus concerning this invention made to consider also a fluctuation | variation.

  In FIG. 4, for simplification of description, parts having the same functions as those of the image forming apparatus shown in FIG.

  In the second embodiment, the voltage detection circuit 102 is connected to the primary side of the smoothing circuit 17 of the power supply device 10, and the voltage / frequency / phase recognition unit 301 of the control unit 30 is based on the output of the current detection circuit 19. In addition to recognizing the frequency and phase of the commercial AC power supply 1, voltage fluctuations in the commercial AC power supply 1 based on the detection output of the voltage detection circuit 102 are recognized.

  The target value table 302 stores target values such as the ON time, OFF time, OFF temperature, ON temperature, and wave number control period of the halogen lamp 21 corresponding to the voltage, frequency, and phase of the commercial AC power supply 1 in advance. Is done.

  The fixing device control unit 33 then sets the target value based on the temperature and voltage / frequency / phase recognition unit 301 of the commercial AC power supply 1 recognized by the temperature and voltage / frequency / phase recognition unit 301 detected by the temperature detection sensor 22. With reference to each target value stored in the table 302, the switching control signal is dynamically corrected. Other configurations are the same as those of the first embodiment shown in FIG.

  According to such a configuration, the correction control of the switching control signal corresponding to the voltage fluctuation of the commercial AC power supply 1 can be performed.

  In the second embodiment, the voltage detection circuit 102 is connected to the primary side of the smoothing circuit 17 of the power supply device 10 so as to detect the voltage fluctuation of the commercial AC power supply 1, but the voltage detection circuit 102 is smoothed. It may be configured to be connected to the secondary side of the circuit 17 to indirectly detect the voltage fluctuation of the commercial AC power supply 1.

  In addition to the voltage, frequency and phase of the commercial AC power supply 1, the ON time, OFF time, OFF temperature, ON temperature, wave number control period, etc. of the halogen lamp 21 differ depending on the power saving control state by the power saving control 34. The primary side voltage or the secondary side voltage of the transformers 15 and 17 to which the switches 13 and 14 controlled by the power saving control 34 are connected is detected, and the target value corresponding to these voltages is stored in the target value table 302. If stored, finer wave number control becomes possible.

  In the first and second embodiments, the switching signal is corrected by recognizing the frequency and phase of the commercial AC power supply 1 based on the output of the current detection circuit 19, but the switching element 12 is turned on and off. The voltage, frequency, and phase of the commercial AC power supply 1 may be recognized from the voltage drop caused by the current controlled by the above, and the switching signal may be corrected.

  Further, the temperature of the component of the primary side circuit of the power supply device 10, for example, the switching element 12 is detected, the temperature increase rate and the temperature increase of the switching element 12 are recognized based on this detection output, and the switching signal You may comprise so that correction | amendment may be performed. Next, Example 3 in which the rate of temperature rise and the temperature rise of the switching element 12 are also considered.

  FIG. 5 illustrates a fixing device that detects a voltage variation of the power supply device 10 based on a voltage drop of the impedance element 11 of the primary circuit 100 of the power supply device 10 and detects a temperature variation of the switching element 12 by the temperature detection circuit 103. FIG. 6 is a block diagram showing a main part of a third embodiment of the image forming apparatus according to the present invention configured to correct a switching control signal in wave number control of a control unit 33;

  In FIG. 5 as well, in order to simplify the description, portions having the same functions as those of the image forming apparatus shown in FIG.

  In the third embodiment, a voltage detection circuit 102 is connected to the impedance element 11 of the primary circuit 100 of the power supply device 10, voltage fluctuations of the power supply device 10 are detected by the voltage detection circuit 102, and A temperature detection circuit 102 is connected to the switching element 12 of the primary side circuit 100, and the temperature of the switching element 12 is detected by the temperature detection circuit 102.

  In this case, the recognition unit 303 recognizes the voltage, frequency, and phase of the commercial AC power supply 1 based on the output of the voltage detection circuit 102, and recognizes the temperature increase rate and increase value of the switching element 12 based on the output of the temperature detection circuit 102. To do.

  Further, the target value table 304 includes an ON time, an OFF time, an OFF temperature, an ON temperature of the halogen lamp 21 corresponding to the voltage, frequency and phase of the commercial AC power supply 1 and the temperature increase rate and the increase value of the switching element 12. A target value such as a wave number control period is stored in advance.

  Then, the fixing device control unit 33 detects the temperature of the halogen lamp 21 detected based on the output of the temperature detection sensor 22, the voltage, frequency, phase of the commercial AC power source 1 recognized by the recognition unit 303, and the temperature increase rate of the switching element 12. Based on the increase value, referring to each target value stored in the target value table 302, the switching control signal for controlling on / off of the switching element 12 is dynamically corrected. Other configurations are the same as those of the first embodiment shown in FIG.

  FIG. 6 is a diagram illustrating an example of control of the fixing device 20 by the fixing device control unit 33 illustrated in FIG.

  When it is detected that the temperature of the halogen lamp 21 has decreased below the ON temperature target value based on the output of the temperature detection sensor 22, the fixing device control unit 33 instructs the halogen lamp to be turned on by a halogen lamp ON / OFF signal. First, the switching control signal is controlled to “half cycle ON, 1 cycle OFF”, and wave number control is performed so that the switching element 12 is “half cycle ON, 1 cycle OFF”.

  In the wave number control in this case, the commercial AC power stored in the target value table 304 is based on the voltage, frequency and phase of the commercial AC power source 1 recognized by the recognition unit 303 and the temperature rise rate and the rise value voltage of the switching element 12. Refer to target values such as the ON time, OFF time, OFF temperature, ON temperature, and wave number control period of the halogen lamp 21 corresponding to the voltage, frequency and phase of the power source 1 and the temperature increase rate and increase value of the switching element 12. The switching control signal for turning on / off the switching element 12 is dynamically corrected.

  Note that the temperature rise rate and the rise value of the switching element 12 can be recognized by differentiating or integrating the output of the temperature detection circuit 102 in the recognition unit 303.

  According to such a configuration, even if the voltage, frequency and phase of the commercial AC power supply 1 and the temperature rise rate and the rise value of the switching element 12 fluctuate, the inrush current can be effectively suppressed and the flicker can be suppressed satisfactorily. it can.

  When the wave number control detects that the inrush current is stable, the switching control signal is controlled to be continuously ON, and the wave number control is terminated.

  When the temperature of the halogen lamp 21 exceeds the OFF temperature target value, the switching control signal is continuously turned off to instruct the halogen lamp to be turned off.

  In the third embodiment, the temperature of the switching element 12 is detected by the temperature detection circuit 103, and the wave number control is performed in consideration of the temperature increase rate and the increase value of the switching element 12. 10 may be configured to detect the temperature of the impedance element 11 of the primary circuit 100 and perform wave number control in consideration of the temperature increase rate and the increase value of the impedance element 11.

  In this type of image forming apparatus, if the line impedance of the commercial power supply in the installation environment where the image forming apparatus is installed is large, the flicker value of the image forming apparatus is also affected by the line impedance. Next, a description will be given of a fourth embodiment in consideration of the line impedance of a commercial power source in an installation environment where the image forming apparatus is installed.

  FIG. 7 shows an image formation according to the present invention configured to correct the switching control signal in the wave number control of the fixing device control unit 33 in consideration of the line impedance of the commercial power supply in the installation environment where the image forming apparatus is installed. It is a block diagram which shows the principal part of Example 3 of an apparatus.

  In FIG. 7 as well, in order to simplify the description, parts having the same functions as those of the image forming apparatus shown in FIG.

  In the third embodiment, first, the line impedance 50 of the commercial AC power supply 1 in the installation environment in which the image forming apparatus is installed is detected.

  The line impedance 50 can be calculated from the equivalent circuit shown in FIG.

  In FIG. 8, the voltage of the commercial AC power supply 1 is V0, the line impedance 50 of the commercial AC power supply 1 is R1, the voltage at both ends is V1, the input voltage of this image forming apparatus is Vin, the internal impedance is R2, and the voltage at both ends is V2. When the on-current coefficient of the element 12 is α, the voltage at both ends is V3, the impedance of the halogen lamp 21 is R4, the voltage at both ends is V4, and the current flowing through the halogen lamp 21 is I1, the following relational expression is obtained.

V0 = V1 + V2 + V3 + V4 (1)
V1 = I1 × R1, V2 = I1 × R2, V3 = I1 × α, V4 = I1 × R4
(2)
V0 = I1 × (R1 + R2 + α + R4) (3)
Vin = V2 + V3 + V4 (4)
Here, the internal impedance R2 is a fixed value, and V2 and I1 can be detected. Α is a fixed value based on the element characteristics of the switching element 12. R4 can be detected.

  Therefore, detection means for V2, V3, and V4 are provided, and the calculation result of the input voltage Vin in the state of I1 = 0 when no current flows through the halogen lamp 21 is recognized as the voltage V0 of the commercial AC power supply 1, and the halogen lamp 21 The value R1 of the line impedance 50 of the commercial AC power supply 1 in the installation environment in which the image forming apparatus is installed can be predicted based on the calculation result of the input voltage Vin in a state where a current flows in

  By storing the value R1 of the line impedance 50 in the target value table 304, it is possible to perform flicker suppression control in consideration of the line impedance 50 of the commercial power source in the installation environment where the image forming apparatus is installed.

  In the fourth embodiment, in addition to the flicker suppression control corresponding to the frequency and phase fluctuation of the commercial AC power supply 1 shown in the first embodiment, the flicker suppression control considering the line impedance 50 can be performed. In addition to the flicker suppression control in the fourth embodiment, the flicker suppression control in consideration of the voltage fluctuation of the commercial AC power source 1 in the second embodiment described above, and the temperature increase rate and the temperature increase of the switching element 12 in the third embodiment are also considered. Flicker suppression control may be implemented in combination.

  As described above, according to the first to third embodiments, it is possible to stably perform a desired wave number control without providing a means for detecting the frequency and phase of the commercial AC power supply. The flicker level can be surely suppressed without being affected. Moreover, cost reduction and size reduction can be realized.

  Further, according to the fourth embodiment, appropriate and sufficient flicker suppression control corresponding to the variation in line impedance of the commercial AC power supply becomes possible, and unnecessary flicker suppression control is not performed. The performance is improved, and the warm-up time of the fixing device can be shortened.

  In addition, since the frequency and phase of the commercial AC power supply are recognized based on the current detection of the halogen lamp by the internal impedance, effective flicker suppression control corresponding to the commercial power supply frequency variation is possible without providing a zero cross detection means. Become.

  In the above-described embodiment, the case where the flicker suppressing device and the flicker suppressing method according to the present invention are applied to an image forming apparatus having a fixing device driven by a commercial AC power supply has been described. Any device other than the image forming apparatus can be applied as long as the device has a heat generating portion that generates heat by adding a heat.

  The flicker suppressing device and the flicker suppressing method of the present invention can be applied to an image forming apparatus having a heat generating portion that generates heat by applying an output of an AC power source.

  According to the present invention, in a device having a heat generating part that generates heat by applying the output of an AC power supply, the current flowing through the heat generating part is detected by the current detecting means, the temperature of the heat generating part is detected by the temperature detecting means, and the temperature detection Based on the detection output of the means and the detection output of the current detection means, the frequency and phase of the AC power supply are recognized by the recognition means based on the detection output of the current detection means, and the detection output of the temperature detection means and the AC power supply recognized by the recognition means Since the switching timing of the switching element that switches the current flowing through the heat generating portion is corrected based on the frequency and phase, flicker can be effectively suppressed with a simple configuration.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a main part of a first embodiment of an image forming apparatus configured by applying a flicker suppressing apparatus and a flicker suppressing method according to the present invention. It is a figure explaining flicker suppression by wave number control. FIG. 2 is a diagram illustrating an example of control of a fixing device by a fixing device control unit illustrated in FIG. 1. It is a block diagram which shows the principal part of Example 2 of the image forming apparatus comprised by applying the flicker suppression apparatus and flicker suppression method concerning this invention. It is a block diagram which shows the principal part of Example 3 of the image forming apparatus comprised by applying the flicker suppression apparatus and flicker suppression method concerning this invention. FIG. 6 is a diagram illustrating an example of control of a fixing device by a fixing device control unit illustrated in FIG. 5. It is a block diagram which shows the principal part of Example 4 of the image forming apparatus comprised by applying the flicker suppression apparatus and flicker suppression method concerning this invention. 10 is an equivalent circuit illustrating the principle of line impedance detection in the fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Commercial AC power supply 10 Power supply device 11 Impedance element 12 Switching element 13, 14 Switch 15 Transformer 16 Smoothing circuit 17 Transformer 18 Smoothing circuit 19 Current detection circuit 20 Fixing device 21 Halogen lamp 22 Temperature detection sensor 30 Control unit 31 Frequency / phase recognition unit 32 Target value table 33 Fixing device control unit 34 Power saving control unit 40 Drive device 50 Line impedance 100 Primary side circuit 101 Voltage detection circuit 102 Voltage detection circuit 103 Temperature detection circuit 301 Voltage / frequency / phase recognition unit 302 Target value table 303 Recognizing unit 304 Target value table

Claims (10)

In a flicker suppressing device for a device having a heat generating part that generates heat by applying an output of an AC power supply,
A switching element for switching a current flowing from the AC power source to the heat generating portion;
Current detecting means for detecting a current flowing through the heat generating portion;
Temperature detecting means for detecting the temperature of the heat generating part;
A flicker suppressing device comprising: wave number control means for controlling switching timing of the switching element based on the detection output of the temperature detection means and the detection output of the current detection means. The wave number control means includes
Recognition means for recognizing the frequency and phase of the AC power supply based on the detection output of the current detection means;
Switching control signal generating means for generating a switching control signal to be applied to the switching element;
A target value table for storing a target value for switching timing correction of the switching control signal corresponding to the frequency and phase of the AC power supply;
And a signal correction unit that corrects the switching control signal with reference to the target value stored in the target value table based on the frequency and phase of the AC power source recognized by the recognition unit. Item 2. The flicker suppressing apparatus according to Item 1. The wave number control means includes
2. The state of the wave number control by the wave number control unit is recognized based on the detection output of the current detection unit, and the control period of the wave number control is controlled based on the recognized state of the wave number control. Or the flicker suppression apparatus of 2 description. Voltage detection means for detecting the output voltage of the AC power supply,
The wave number control means includes
The voltage, frequency and phase of the AC power supply are recognized based on the detection output of the voltage detection means, and the switching control signal is corrected based on the recognized voltage, frequency and phase of the AC power supply. Item 4. The flicker suppressing device according to any one of Items 1 to 3. The voltage detection means includes
The flicker suppression apparatus according to claim 4, wherein the output voltage of the AC power supply is indirectly detected from a primary circuit or a secondary circuit of a power supply circuit that converts the output voltage of the AC power supply. The voltage detection means includes
The flicker suppressing apparatus according to claim 4, wherein an output voltage of the AC power supply is detected based on a voltage drop due to a current flowing through the switching element. Line impedance detection means for detecting the line impedance of the AC power supply,
The wave number control means includes
The flicker suppression apparatus according to any one of claims 1 to 6, wherein a control period of the wave number control is controlled based on a detection output of the line impedance detection means. The line impedance detection means includes
The detection is performed by calculating the line impedance based on an input voltage from the AC power supply to the device, an internal impedance of the device, an on-impedance of the switching element, and an impedance of the heat generating unit. Flicker suppression device. In a fixing device of an image forming apparatus having a heat generating portion that generates heat by applying an output of an AC power supply,
A switching element for switching a current flowing from the AC power source to the heat generating unit;
Current detecting means for detecting a current flowing through the heat generating portion;
Temperature detecting means for detecting the temperature of the heat generating part;
A fixing device for an image forming apparatus, comprising: a flicker suppressing device comprising: a wave number control unit that controls a switching timing of the switching element based on a detection output of the temperature detection unit and a detection output of the current detection unit. . In a method for suppressing flicker of a device having a heat generating part that generates heat by applying an output of an AC power supply,
The current flowing through the heat generating part is detected by current detection means,
Detecting the temperature of the heat generating part by means of temperature detecting means;
Recognizing the frequency and phase of the AC power supply by the recognition means based on the detection output of the current detection means,
The flicker is characterized by correcting the switching timing of the switching element for switching the current flowing through the heat generating part based on the detection output of the temperature detection means and the frequency and phase of the AC power source recognized by the recognition means by the wave number control means. Suppression method.

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