JP5018224B2 - Image forming apparatus and power conversion method - Google Patents

Description

This invention relates to an image forming apparatus having a power converter used to power the heat source of Netsujo deposition apparatus, and a power conversion method executed in the image forming apparatus.

  In general, for example, in a heat fixing device in an image forming apparatus, there is a heat roller type or belt type heating unit that fixes a toner image while passing the recording paper on which the toner image is transferred between a heating roller and a pressure roller. A halogen heater or the like is used as a heat source that is used and is a power load.

  By the way, in the image forming apparatus, since the power consumption in the thermal fixing device occupies a large weight, the reduction of the power consumption in the thermal fixing device leads to energy saving of the entire image forming apparatus. become. For this reason, for example, by keeping the temperature of the heating roller constant during standby for thermal fixing operation, the temperature can be increased to a temperature at which heat fixing can be performed in a short time during thermal fixing. By keeping the temperature constant, electric power (about 70% of the whole) is consumed even when the heat fixing device is not used.

  Therefore, it is common to save energy by providing a mode (low power mode or sleep mode) for reducing power during standby.

  However, if the temperature of the heating roller in the thermal fixing device decreases, the waiting time for the next use becomes longer, so if the temperature of the heating roller decreases, a large electric power is applied at the time of warm-up, and the temperature at which fixing is possible Measures to raise at a stretch are taken.

  In addition, electromagnetic induction heating systems capable of rapid heating and high-efficiency heating are attracting attention because of demands for shortening warm-up time and energy saving. It is often used and the maximum amount of power input is limited.

  In order to improve this, conventionally, in the heat fixing device, an auxiliary heat source by a DC auxiliary power source is separately prepared, and the power of both the main power source and the auxiliary power source is supplied to the heat source, thereby shortening the warm-up time. Methods are also known.

On the other hand, conventionally, a technique has been proposed in which conduction control is performed on a heat source and AC / DC is switched when power is supplied to the heat source (see, for example, Patent Document 1).
JP 2004-184963 A

  However, in the above-described prior art, at the time of warm-up, both the AC power source and the DC power source must be operated, and separate heat sources are provided for the main power source and the auxiliary power source, so the configuration becomes complicated.

  In addition, as in the technique described in Patent Document 1, simply switching between AC and DC when supplying power to the heat source cannot obtain the same specified power value in the case of AC and in the case of DC, High-precision power control cannot be performed.

The present invention has been made in view of the above circumstances, and it is not necessary to provide a heating heat source for the fixing device for each AC and DC power source , and an AC main power source and a DC auxiliary for one heating heat source . Power conversion that can cope with the upper limit of the input amount of AC power by switching one of the power supplies, and can supply equivalent power with any power supply and perform highly accurate power control on the heat source An object of the present invention is to provide an image forming apparatus including the apparatus and a power conversion method executed by the image forming apparatus .

The above problem is solved by the following means.
(1) A fixing device having a heating heat source and a power conversion device that supplies power to the heating heat source, wherein the power conversion device supplies power from an AC power source to the heating heat source and from a DC power source. Switching means for switching power supply and a switching element, and by switching operation of the switching element, the power from the AC power source or the power from the DC power source switched by the switching means is changed from the power from the AC power source and the DC power source. the power and the inverter to be supplied to said heating heat source waveform is converted to a different radio frequency output at the time of power supply from the DC power supply and when power supply from the AC power source has been switched by said toggle means, equivalent image type, wherein the power is provided and a control unit for controlling the inverter to be supplied to said heating heat source Apparatus.
(2) the control means, correction and peak value of the output of the inverter when it is switched to the power from the AC power supply, the ratio between the peak value of the output of the inverter when it is switched to the power from the DC power source 2. The image forming apparatus according to item 1, wherein equivalent power is supplied to the heating heat source by performing power control.
(3) The image forming apparatus according to (1) or (2), wherein the control unit performs control of electric power supplied to the heating heat source with an integral multiple of a half cycle of an AC power supply as one unit.
(4) In the image forming apparatus, the switching is performed by a switching step of switching power supply from an AC power supply to a heat source for heating of the fixing device and power supply from the DC power supply, and switching operation of the switching element of the inverter having the switching element. Converting the power from the AC power source or the power from the DC power source into a high frequency output having different waveforms between the power from the AC power source and the power from the DC power source and supplying the high frequency output to the heating heat source, and the switching And controlling the inverter so that equivalent power is supplied to the heating heat source when power is supplied from the AC power source and when power is supplied from the DC power source. Power conversion method executed in

According to the invention described in the preceding paragraph (1), when either one of the power from the AC power source or the power from the DC power source is input to the inverter through the switching means, this input is converted into the power from the AC power source. The power is converted into a high-frequency output having a waveform different from that of the power from the DC power supply and supplied to the heating heat source of the fixing device . Control circuit, when the power supply from the DC power supply and when power supply from the AC power source has been switched by the cut re unit, equivalent power to control the power to be supplied to the heating source for heating from the inverter.

That is, without providing a heat source for each AC power source and DC power source , power can be supplied from either the AC power source or the DC power source to one heating heat source . For example, power supply by the AC power source to the heating heat source When there is an upper limit, the power equivalent to that of the AC power source can be supplied to the heating heat source using the DC power source . Moreover, since the equivalent power is supplied from the inverter to the heating heat source both when supplying power from the AC power source and when supplying power from the DC power source , it is possible to perform highly accurate power control on the heating heat source . it can. Therefore, when there is an upper limit to the power supply by the AC power source, such as when the heat fixing device is warmed up, the DC power source can be used to supply power equivalent to that of the AC power source to the heat source of the heat fixing device. The image forming apparatus can be made.

According to the invention described in item (2), the control means converts the peak value of the output of the power conversion means when switched to power from the AC power supply and the power conversion when switched to power from the DC power supply. By performing power control that corrects the ratio to the peak value of the output of the means, it is possible to accurately heat equivalent power with relatively simple control when supplying power from an AC power supply and when supplying power from a DC power supply . It can be supplied to a heat source .

According to the invention described in item (3) above, since the power supplied to the heating heat source is controlled by an integral multiple of a half cycle of the AC power supply as one unit, the power supply from the AC power supply and the DC power supply At the time of power supply from, an equivalent power can be reliably supplied to the heating heat source .

According to the invention described in item (4) above, when there is an upper limit in the power supply by the AC power source to the heating heat source of the fixing device , the DC power source is used to supply power equivalent to that in the AC power source for the heating. Can be supplied to a heat source .

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a thermal fixing device of an image forming apparatus in which a power conversion device according to the present invention is used.

  In FIG. 1, the thermal fixing device includes a heating roller 1, a pressure roller 2, a heating unit 3 as a heat source as a load, and a temperature detection unit 4.

  The heating roller 1 is rotated by a driving force from a rotation driving source (not shown), and when the recording paper 6 onto which the toner image has been transferred is passed through the nip portion 5 between the heating roller 1 and the pressure roller 2, the heating roller 1 is heated. The toner image is fixed on the recording paper as an image.

  The heating unit 3 heats the heating roller 1. For example, an electromagnetic induction coil that directly heats the heating roller 1 is used. Of course, the heat source is not limited to the electromagnetic induction coil, and a heating element such as a heater may be employed. Moreover, the structure which incorporated this heating part 3 in the heating roller 1 may be sufficient.

  The temperature detection unit 4 detects the heating temperature by the heating unit 3, that is, the temperature of the heating roller 1, and sends the temperature detection signal to the heat fixing control unit (see FIGS. 2 and 3) 21. It has become.

  Here, an example of a conventional general power converter will be described with reference to the block diagram showing the electrical configuration of FIG.

  In FIG. 2, the power conversion apparatus includes an AC power supply 12, an inverter 11 as power conversion means, the heating unit 3, the temperature detection unit 4, and a thermal fixing control unit 21.

  The inverter 11 converts commercial AC power supplied from the AC power source 12 through the commercial power supply path 13 into high-frequency alternating power using a switching operation of a switching element (not shown), and heats the heating through the high-frequency power supply path 14. It supplies to the part 3.

  As the switching element, for example, a known element such as a MOSFET, IGBT, or transistor is used.

  The thermal fixing controller 21 receives the temperature detection signal 22 from the temperature detector 4 and sends an output power control signal 23 to the inverter 14 to control the output of the inverter 14.

  As described above, commercial AC power supplied from the AC power supply 12 through the commercial power supply path 13 is converted into high-frequency power by the inverter 11 and supplied to the heating unit 3 through the high-frequency power supply path 14. The heating roller 1 is heated by the heat generating action.

  When the temperature detection signal 22 from the temperature detection unit 4 that detects the temperature of the heating roller 1 is output to the thermal fixing control unit 21, an output power control signal 23 corresponding to the temperature detection value is output by the thermal fixing control unit 21. Applied to the inverter 11. The inverter 11 generates high-frequency power corresponding to the output power control signal 23 from the thermal fixing control unit 21.

  When the high frequency power is supplied to the heating unit 3 through the high frequency power supply path 14, the heating roller 1 is heated by the heat generated by the heating unit 3. That is, the heating roller 1 is controlled to be heated to a constant temperature by a control loop of the temperature detection unit 4, the thermal fixing control unit 21, and the inverter 11.

  FIG. 3 is a block diagram showing an electrical configuration of the power conversion device according to the embodiment of the present invention.

  In FIG. 3, in this power converter, in addition to the inverter 11 and the heat fixing controller 21 having the same configuration as in FIG. 2, a rectifier 45 is provided on the output side of the AC power source 12, Moreover, the electrical storage part 15 as a DC power supply is provided.

  Further, the output terminal of the rectifying unit 45 and the output terminal of the power storage unit 15 are selected as the input terminals of the inverter 13 so that the output of the AC power supply 12 or the output of the power storage unit 15 can be selected as the input to the inverter 13. In addition, a switching unit 43 that can be switched and connected is provided. The switching unit 43 is switched by a switching instruction signal 44 sent from the thermal fixing control unit 21.

  Further, an input detection unit 41 is interposed between the input side of the inverter 11 and the thermal fixing control unit 21. The input detection unit 41 detects the input (input voltage or input current) of the inverter 11 and sends an input detection signal 42 to the thermal fixing control unit 21.

  Furthermore, an output detection device 31 that detects high-frequency power output from the inverter 11 is interposed between the output side of the inverter 11 and the input side of the thermal fixing control unit 21. When detecting the high frequency power output from the inverter 11, the output detection device 31 sends an output detection signal 32 to the thermal fixing controller 21.

  The output detection device 31 may detect the output current of the inverter 11 instead of detecting the high-frequency power from the inverter 11.

  The thermal fixing control unit 21 receives the input detection signal 42, the output detection signal 32, the temperature detection signal 22 from the temperature detection unit 4, and the like, and controls the high-frequency power by the inverter 11 to an arbitrary set value. Can do.

  Further, the type of input to the inverter 11 when outputting the high frequency power is determined from the input detection signal 42 of the input detection unit 41, and the high frequency power value and frequency from the inverter 11 are determined as the output detection signal of the output detection device 31. Can be confirmed. Further, it can be determined from the input detection signal 42 whether the power storage unit 15 has an output equal to or greater than a predetermined threshold.

  Further, the thermal fixing control unit 21 receives the temperature detection signal 22 from the temperature detection unit 4 and controls the high frequency power so as to become the specified temperature value, and also receives the input detection signal 42 from the input detection unit 41. The type of input to the inverter 11, that is, whether the output has been switched to the output from the AC power supply 12 or the output from the power storage unit 15 is confirmed. The inverter 11 is controlled so that high frequency power equivalent to the case of the unit 15 is output. The determination of whether the power supplied to the inverter is from the AC power source 12 or the power storage unit 15 may be made based on a switching command from the overall control unit or the like of the image forming apparatus.

  Further, the thermal fixing control unit 21 detects the period of the AC power supply 12 based on the input detection signal 42 of the input detection unit 41. And the high frequency power from the said inverter 11 is detected via the said output detection apparatus 31 for every unit by making integral multiple of T1 (FIG. 4) time which is a half cycle of the alternating current power supply 12 into 1 unit, and according to the detection result The output waveform of the switching signal by the switching element in the inverter 11 is determined, and the electric power supplied from the inverter 11 to the heating unit 3 is controlled.

  The switching signal may be a signal based on a PWM (Pulse Width Modulation) system that changes the energization width, or may be a signal based on a frequency control system.

  Further, the thermal fixing control unit 21 may control only the thermal fixing device or may be configured by a control unit that controls the overall operation of the image forming apparatus.

  FIG. 4 shows a waveform diagram of each part in the power conversion device of FIG. 3.

  In FIG. 4, a waveform 1 a indicates a rectification (full wave rectification) output voltage waveform of the AC power supply 12, and a waveform 2 a indicates an output voltage waveform of the power storage unit 15.

  Waveform 1A shows the output waveform of inverter 11 when switched to power from AC power supply 12, and waveform 2A shows the output waveform of inverter 11 when switched to power from power storage unit 15.

  When power supply from the AC power supply 12 and power supply from the power storage unit 15 are switched as power supply to the inverter 11, if the output from the inverter 11 is not equivalent, it is supplied to the heating unit 3. Electric power will be different, and high-precision control cannot be performed.

  Therefore, in this embodiment, the output value (waveform 1A) of the inverter 11 detected by the output detection device 31 when the power is switched from the AC power supply 12 and the output detection when the power is switched from the power storage unit 15. Control is performed so that the output value (waveform 2A) of the inverter 11 detected by the device 31 becomes equivalent.

  Specifically, the peak value of the output voltage of the inverter 11 when the power is switched from the AC power supply 12 is W1, and the peak value of the output voltage of the inverter 11 is switched to the power from the power storage unit 15. Is W2, the inverter 11 is controlled by the thermal fixing controller 21 so that the following equation is obtained.

W1 / W2 = k
(However, k: coefficient, theoretically k = √2, but is arbitrarily set according to the conditions).

  In addition to the method of correcting the output value to be equivalent using the coefficient k as described above, the correction is performed by storing all the peak voltage values of the high frequency output of the inverter 11 over one cycle of the AC power supply 12. Alternatively, the output value of the inverter 11 may be detected by the output detection device 31 using an integration circuit using a time constant, and the output value may be corrected based on the result.

  In the power conversion device having the above configuration, either the power from the AC power source 12 or the power from the power storage unit 15 that is a DC power source is switched by the switching unit 43 and input to the inverter 11.

  The selected input is converted into high frequency power by the switching operation of the switching element inside the inverter 11 and then supplied to the heating unit 3. Therefore, the heating unit 3 generates heat and the heating roller 1 is heated. The

  The temperature of the heating roller 1 is detected by the temperature detector 4 and a temperature detection signal 32 is applied to the thermal fixing controller 21. The input detection unit 41 detects the input type for the inverter 11, and the input detection signal 42 is applied to the thermal fixing control unit 21. Further, the output detection device 31 detects the output from the inverter 11, and the output detection signal 32 is applied to the thermal fixing controller 21.

  The heat fixing control unit 21 controls the inverter 11 so that when switched to power from the AC power source 12 or power from the power storage unit 15, high-frequency power equivalent to that before switching is output from the inverter 11. .

  With such a configuration, equivalent high-frequency power is supplied to the heating unit 3 with respect to one heating unit 3 regardless of the power from the AC power supply 12 and the power from the power storage unit 15. Therefore, when there is an upper limit in the power supply from the AC power supply 12 at the time of warming up the heat fixing device, the power supply from the power storage unit 15 can be immediately switched to be supplied to the heating unit 3.

  FIG. 5 is a flowchart showing power control processing by the thermal fixing control unit 21.

  In FIG. 5, in step S1, the thermal fixing controller 21 receives the temperature detection signal 22 from the temperature detector 4, and determines whether or not the detected temperature is higher than a specified value.

  If the detected temperature is higher than the specified value (YES in step S1), in step S3, the thermal fixing control unit 21 controls the output power control signal 23 so that the power value output from the inverter 11 is reduced. Then, the process proceeds to step S4. If the detected temperature is lower than the specified value (NO in step S1), in step S2, the thermal fixing control unit 21 increases the power value output from the inverter 11 by the output power control signal 23 to the inverter 11. Then, the process proceeds to step S4.

  In step S1, a threshold value of the detected temperature is provided and this threshold value is used as a criterion for determination. However, a plurality of threshold values may be set, and the amount of increase or decrease in power may be changed for each threshold value.

  In step S4, for example, it is determined whether or not an input (power supply) switching command is issued from the overall control unit of the image forming apparatus. If there is no switching command (NO in step S4), the process proceeds to step S6. If there is an input switching command (YES in step S4), in step S5, a switching instruction signal 44 is sent to the switching unit 43 to perform a switching operation, and then the process proceeds to step S6.

  In step S6, it is determined whether or not the power supply to the inverter 11 is the power supply from the power storage unit 15. If the power supply from the AC power supply 12 is not the power output from the power storage unit 15 (NO in step S6). In step S7, the output detection value from the output detection device 31 (peak value W1 in FIG. 4) is determined to be multiplied by a factor k (for example, √2), and in step S9, switching of the switching element in the inverter 11 is performed. Finish after determining the signal waveform. If power is supplied from the power storage unit 15 in step S6 (YES in step S6), in step S8, the output detection value from the output detection device 31 (peak value W2 in FIG. 4) is used as it is without correction. In step S9, the switching signal waveform of the switching element in the inverter 11 is determined, and the process ends.

1 is a schematic configuration diagram illustrating a thermal fixing device in an image forming apparatus in which a power conversion device according to an embodiment of the present invention is used. It is a block diagram which shows the electric constitution of the power converter device generally used conventionally. It is a block diagram which shows the electric constitution of the power converter device which concerns on one Embodiment of this invention. It is a wave form diagram of each part in the power converter device of FIG. It is a flowchart which shows the electric power control process by a heat fixing control part.

Explanation of symbols

3 Heating part (heat source, load)
4 Temperature detector 11 Inverter (Power conversion means)
12 AC power supply 15 Power storage unit 21 Thermal fixing control unit 22 Temperature detection signal 31 Output detection unit 41 Input detection unit 43 Switching unit

Claims (4)

A fixing device having a heating heat source, and a power converter that supplies power to the heating heat source,
The power converter is
Switching means for switching between power supply from the AC power source and power supply from the DC power source to the heating heat source ;
A switching element, and the switching operation of the switching element causes the power from the AC power source or the power from the DC power source switched by the switching means to have different waveforms between the power from the AC power source and the power from the DC power source. An inverter that converts the output and supplies the heat source for heating ;
And control means for controlling the inverter so that the switching time of the power supply from the switched AC power supply and the Toggles means when power supply from the DC power supply, an equivalent power is supplied to the heating heat source,
An image forming apparatus comprising: The control means, the power control for correcting the peak value of the output of the inverter when it is switched to the power from the AC power supply, the ratio between the peak value of the output of the inverter when it is switched to the power from the DC power source The image forming apparatus according to claim 1, wherein equivalent electric power is supplied to the heating heat source by performing. The image forming apparatus according to claim 1, wherein the control unit controls the power supplied to the heat source for heating with an integral multiple of a half cycle of an AC power supply as one unit. A switching step of switching between power supply from an AC power supply and power supply from a DC power supply to a heat source for heating the fixing device in the image forming apparatus;
The switching operation of the switching element of the inverter having a switching element causes the power from the switched AC power supply or the power from the DC power supply to have a high-frequency output having a different waveform between the power from the AC power supply and the power from the DC power supply. And converting it into the heat source for heating,
Controlling the inverter so that equivalent power is supplied to the heating heat source when supplying power from the switched AC power source and when supplying power from the DC power source;
A power conversion method executed by an image forming apparatus.

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