JP4774349B2 - DC power supply device and image forming apparatus - Google Patents

Description

  The present invention relates to a DC power supply device including an active filter, and an image forming apparatus such as a copying machine, a facsimile, a printer, and a digital multifunction peripheral including the DC power supply device.

  In image forming apparatuses such as copiers, facsimiles, printers, copiers, facsimiles, and multifunction machines equipped with printing functions, harmonic currents generated from the apparatus flow out to the power system and share not only the image forming apparatus but also the power source. There was a problem of adversely affecting other electronic devices. This is because most DC power supply devices except high power power supply devices or some special power supply devices employ a capacitor input type rectifier circuit, so the AC input current has a narrow pulse-like waveform, This is due to the inclusion of many harmonic currents.

  One effective means of suppressing this harmonic current and improving the power factor is an active filter. This active filter is inserted between the input rectifier circuit of the conventional switching power supply and the DC / DC converter. The active filter improves the power factor by controlling the waveform of the current input from the rectifier circuit to be a smooth waveform close to a sine wave, and reduces the harmonic component of the input current. Known as. As such an active filter, various types such as a step-up type, a step-down type, and a step-up / step-down type have been proposed.

  FIG. 11 is a block diagram showing an example of a conventional DC power supply device. In the figure, a DC power supply device 1 provided at a subsequent stage of an AC power supply 10 includes a rectifier circuit 2, a power factor correction circuit 3, and first to third DC / DC converters 4, 5, and 6. The rectifier circuit 2 is provided in the forefront stage of the DC power supply device 1 and rectifies the AC input from the AC power supply 10. A power factor improvement circuit 3 is provided at the subsequent stage of the rectifier circuit 2 to improve the power factor with respect to the input current rectified by the rectifier circuit 2 and reduce harmonic components. The output from the power factor correction circuit 3 is input to first and second DC / DC converters 4 and 5 provided in parallel, respectively. The output voltage-converted by the first DC / DC converter is input to the first load 7, and the output voltage-converted by the second DC / DC converter is the second load 8 and the third DC / DC converter 6. Are respectively input to the third load 9.

  As described above, in the DC power supply device 1, the first to third DC / DC converters 4, 5, 6 generate multiple systems of DC voltages, and efficiently supply power to the loads 7, 8, 9. Yes. Further, on / off of the second DC / DC converter 5 can be controlled by an external on / off signal. Thereby, only the first DC / DC converter 4 can be output in the low power consumption mode (referred to as an energy saving mode in the present specification).

  FIG. 12 is a block diagram showing a schematic configuration of a power supply system of an image forming apparatus in which such a DC power supply device is mounted. In the figure, a control device 13, a scanner / writing device 14, and a conveyance / paper feeding device 15 are connected to the DC power supply device 1 of the image forming apparatus. The control device 13 controls the mechatronic component 11, the scanner / writing device 14, the conveyance / feed device 15, and the DC power supply device 1 based on the detection outputs input from the plurality of sensors 12.

  A mechatronic component (denoted as mechatro in the figure) 11 is a component such as a motor, a solenoid, or a clutch, and a sensor 12 detects the position of various components. The control device 13 controls the mechatronic component 11 and necessary parts of the device while acquiring information from the sensor 12. The scanner / writer 14 is an engine unit and includes a scanner and a writing device. The scanner reads a document image and outputs it as image data. The writing device writes an image on a recording medium such as transfer paper in accordance with image data from a scanner or image data from a PC or the like and outputs it as a hard copy. In accordance with an instruction from the control device 13, the transport / feed device 15 feeds the recording medium to the transfer position and discharges it from the transfer position. The DC power supply device 1 supplies power to the mechatronic component 11 and the sensor 12 via the scanner / writing device 14, the conveyance / paper feeding device 15, and the control device 13.

  The first load 7 shown in FIG. 11 corresponds to the sensor 12 and the control device 13 shown in FIG. 12 and needs to be constantly supplied with power. In the energy saving mode, the DC power supply 1 supplies power only to the first load 1. On the other hand, the second and third loads 8 and 9 correspond to devices such as the mechatronic component 11 that do not need to be operated in the energy saving mode.

For example, in Patent Document 1, in an image forming apparatus having a DC power supply device having an active filter and a regulator, the DC power supply device outputs a power supply voltage by the active filter and the regulator at the time of image formation. It has been proposed that a power supply voltage is output by a regulator without using an active filter during standby for formation. Further, for example, Patent Document 2 proposes that an image forming apparatus having a power supply device including an active filter includes a control device that controls the operation of the active filter, and the active device is operated or stopped by the control device. ing.
Japanese Patent No. 3466351 JP-A-9-121538

  However, in the previous DC power supply devices, when AC power is turned on, the active filter is always used regardless of the size of the load connected between the output terminals of the DC / DC converter, load fluctuation, or energy saving mode. Starts continuous operation, so that power consumption is generated at any time in the components constituting the active filter circuit. Then, since each voltage is output after the operation of the active filter, a relatively long rise time occurs.

  The present invention has been made in view of such a state of the art, and a problem to be solved is to reduce power consumption and shorten rise time in the energy saving mode.

In order to solve the above-described problem, a first means of the present invention includes a rectifier circuit that rectifies an AC voltage input from an AC power supply, and an AC that is provided in parallel to the subsequent stage of the rectifier circuit and rectified by the rectifier circuit. a plurality of D C / DC converter for outputting a voltage smoothing to the set in parallel downstream of the rectifier circuit vignetting, and power factor improvement circuit for improving the power factor of the rectified AC voltage, said rectifying circuit In the DC power supply apparatus provided with the switch means provided between the power factor improvement circuit and inactivating the power factor improvement circuit in the energy saving mode , the plurality of DC / DC converters are respectively the same A first DC / DC converter that outputs a potential and is always output even when in the energy saving mode, and is provided at a subsequent stage of the rectifier circuit, and is provided at a subsequent stage of the power factor correction circuit. The second DC / DC converter that does not output at the time of power saving and outputs when not in the energy saving mode, and the power factor improving circuit operates by the ON operation of the switch means, and the second DC / DC converter outputs At least one of another DC / DC converter that supplies the necessary current up to and another DC / DC converter that smoothes the output of the rectifier circuit and supplies the output to the output side of the first DC / DC converter The first DC / DC converter is generated by monitoring when the output current exceeds the output current that can be supplied by the second DC / DC converter by the control means connected to the outside. When the switching signal is received, it is output in an auxiliary manner under the control of the switch means .

The second means is characterized in that, in the first means, the switch means comprises a relay or FET .

According to a third means, in the first means or the second means, each of the plurality of DC / DC converters has an output side connected to a load, and the first DC / DC converter controlled by the switch means and the first DC / DC converter Switching between the two DC / DC converters is performed based on mode switching of the load by the control means .

According to a fourth means, in the first means or the second means, switching between the first DC / DC converter and the second DC / DC converter by the control of the switch means is detected by the control means. It is performed based on the measured current value .

A fifth means is any one of the first means to the fourth means, wherein the another DC / DC converter controls the switching means emitted by the control means. The operation is controlled to be turned on / off in response to a switching signal different from the above.

A sixth means is characterized in that, in the fifth means, the switching signal for controlling the switching means is outputted with a time difference with respect to the switching signal of the other signal .

A seventh means is the same as the sixth means, further comprising a timer or a time constant circuit for setting the time difference .

The eighth means is characterized in that, in the fifth means, the operation of the other DC / DC converter is controlled on / off by the switching signal of the other signal .

The ninth means is characterized in that the image forming apparatus includes the DC power supply device of any one of the first to eighth means.

In each embodiment described below, the rectifier circuit reference number 101, the DC / DC converter the first to sixth DC / DC converter 102,104,105,111,112,121 (other DC / DC converter Is a fourth DC / DC converter 111, another DC / DC converter is a sixth DC / DC converter 121) , a power factor correction circuit is denoted by reference numeral 103, a switch means is a switch element 106, and a timer is a timer IC 131. The time constant circuit corresponds to reference numeral 141, and the control device corresponds to reference numeral 13.

  According to the present invention, it is possible to reduce the power consumption and shorten the rise time in the energy saving mode.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts other than the DC power supply device that are the same as those in the conventional example are denoted by the same reference numerals, and redundant description is omitted.

  1 is a block diagram showing a configuration of a DC power supply apparatus according to Embodiment 1 of the present invention. The DC power supply device 100 according to the first embodiment includes a rectifier circuit 101, a power factor correction circuit 103, first to third DC / DC converters 102, 104, 105, and a switching element 106, and includes first to third loads. 7, 8, and 9 are connected to the first to third DC / DC converters 102, 104, and 105, respectively.

  The first DC / DC converter 102 and the second DC / DC converter 104 are connected in parallel at the subsequent stage of the rectifier circuit 101. In the circuit from the rectifier circuit 101 to the second DC / DC converter 104, A switching element 106 is provided on the front side, and a power factor correction circuit 103 is provided on the rear side. The circuit from the second DC / DC converter 104 to the third load 9 is provided with the third DC / DC converter 105, and the first DC / DC converter 102 is connected to the first load 7 as described above. The second DC / DC converter 104 is connected to the second load 8, and the third DC / DC converter 105 is connected to the third load 9. In addition, a signal line for turning on / off the switching element 106 from the control circuit 13 to the outside of the DC power supply apparatus 100 is connected to the downstream side of the first DC / DC converter 102. The switching element 106 can be turned on / off by controlling on / off of the current flowing through the signal line by the on / off signal from the control circuit 13, that is, the direct current flowing through the coil of the switching element. ing.

  The rectifier circuit 101 is configured by, for example, a diode bridge that performs full-wave rectification on the AC voltage input from the AC power supply 10. The first DC / DC converter 102 to which the output of the rectifier circuit 101 is input turns on / off a switching element connected in series to the primary winding of the transformer to which the output of the rectifier circuit 101 is input. The voltage induced in the secondary winding of the transformer is rectified and smoothed and output to the first load 7 side (A output). The second DC / DC converter 104 rectifies and smoothes the output from the power factor correction circuit 103 on the same principle as the first DC / DC converter 104, and the second load side 8 side and the third DC / DC converter. 105 are output in parallel. The third DC / DC converter 105 also rectifies and smoothes the output from the second DC / DC converter 104 on the same principle as that of the first DC / DC converter 102 and outputs it to the third load 9 side. Here, the output of the second DC / DC converter 104 to the second load 8 side is referred to as B output, and the output of the third DC / DC converter 105 to the third load 9 side is referred to as C output.

  In the DC power supply device 100 in FIG. 1, the A output output from the first DC / DC converter 102 is always output to the first load 7 side even in the energy saving mode without passing through the power factor correction circuit 103. . The second DC / DC converter 104 and the third DC / DC converter 105 are connected to the second DC / DC converter 105 after the switching element 106 is turned on by the ON signal from the control device 13 and the power factor correction circuit 103 is operated. / DC converter 104 outputs B output, and third DC / DC converter 105 outputs C output. As the switching element 106, for example, a relay or FET is used.

  FIG. 2 is a timing chart showing a rising sequence associated with the ON signal output of the A output, B output, C output and ON / OFF signal of FIG. In the sequence, after the DC power supply device 100 is turned on, the output A from the first DC / DC converter 102 rises, the switching element 106 is turned on by the ON signal from the control device 13, and the relay operation and power factor correction circuit After 103 operates, B output and C output rise.

  FIG. 3 is a time chart showing a rising sequence when the switching element 106 of FIG. 1 is changed from a relay to an FET switch. Compared with the sequence of FIG. 2, it can be seen that the relay operation can be shortened, so that the startup time of the B output and the C output can be improved.

  FIG. 4 is a block diagram showing a configuration of a DC power supply apparatus according to Embodiment 2 of the present invention. In the second embodiment, the second DC / DC converter 104 and the power factor correction circuit 103, the second DC / DC converter 104, and the third DC / DC converter 105 arranged in series in the first embodiment are arranged in parallel. A fourth DC / DC converter 111 and a fifth DC / DC converter 112 having the same configuration as the third DC / DC converter 105 are provided, and the current rectified from the rectifier circuit 101 to the fourth DC / DC converter 111. The on / off signal is directly input, the output of the fourth DC / DC converter 111 is input in parallel to the second load 8 and the fifth DC / DC converter 112, and the output of the fifth DC / DC converter 112 is output. Is input to the third load 9.

  In the first embodiment, the B output and the C output are output after the switching element 106 is turned on and the power factor correction circuit 103 is operated as shown in FIG. Time is delayed. Therefore, in the DC power supply device 110 according to the second embodiment, the rise times of the B output and the C output are improved by providing the fourth and fifth DC / DC converters 111 and 112 as described above.

  That is, in the fourth DC / DC converter 111 and the fifth DC / DC converter 112, the power factor correction circuit 103 is operated by the ON operation of the switching element 106, and the second and third DC / DC converters 104 and 105 are operated. Are provided for supplying necessary currents until the B output and the C output are output (at initial startup: system initialization, etc.). Therefore, an ON signal is sent to the fourth DC / DC converter 111 and the switching element 106, and after the operation of the power factor correction circuit 103, the B output and C output from the second and third DC / DC converters 104 and 105 are transmitted. A current corresponding to the output from the fourth and fifth DC / DC converters 111 and 112 is added to the output and supplied to the second load 8 and the load 9.

  This switching of the on / off signal is determined by the control device 13 in the operation mode of the second load 8 and the third load 9, or from the fourth DC / DC converter 111 and the fifth DC / DC converter 112. It can also be determined by detecting the output current value.

  The other parts are configured in the same manner as in the first embodiment and function in the same manner, and thus redundant description is omitted.

  FIG. 5 is a block diagram showing a DC power supply apparatus according to Embodiment 3 of the present invention. The DC power supply device 120 according to the third embodiment includes a sixth DC / DC converter 121 in parallel with the first DC / DC converter 102 of the DC power supply device 100 according to the first embodiment. The second on / off signal from 13 is directly input to the sixth DC / DC converter 121. The sixth DC / DC converter 121 also operates on the same principle as the first DC / DC converter 102. The output of the rectifier circuit 101 is input to the sixth DC / DC converter 121, and the output rectified and smoothed by the sixth DC / DC converter 121 is connected to the output side of the first DC / DC converter 102. The first load 7 is input. The second on / off signal is input independently of the on / off signal in the first and second embodiments (referred to herein as the first on / off signal).

  As described above, the output A is a power source that is output even in the energy saving operation mode as described above, and is a power source that is supplied to the sensor 12 and the CPU of the control device 13. The control device 13 is always operating even when there is no system operation. In order to achieve further energy saving with respect to the DC power supply devices 100 of the first and second embodiments, it is necessary to increase the efficiency of the DC / DC converter. However, if the DC / DC converter is a flyback type in accordance with the demand for high efficiency and low output power, the current that can be supplied is reduced. Further, as in the second embodiment, it may be configured to supply an insufficient current at the time of initial startup from another DC / DC converter. However, since the output A is supplied to the control device 13, the control device 13 Must return to the sixth DC / DC converter 121 before returning to normal operation.

  In the energy saving mode, the power supply to the second load 8 and the third load 9 is stopped, and the control device 13 is always operating as described above. However, the sensor output of the control means 13 (first load 7) is also provided. Only an amount of current for monitoring the external input is supplied, and current during normal control does not flow.

  On the other hand, this type of DC / DC converter includes a so-called overcurrent circuit that opens a circuit to prevent overload when an overcurrent flows. Therefore, when returning from the energy saving state and the control device 13 returns from the minimum drive state to the normal drive state, a large current flows to drive the control device 13. However, if the large current flows before the first DC / DC converter 102 returns to the normal driving state, the power supply to the control circuit 13 side is cut off by the function of the overcurrent circuit, so that the system Will stop.

  For this reason, in the present embodiment, the first on / off signal for turning on / off the switching element 106 and the second on / off signal for turning on / off the sixth DC / DC converter 121 are switched as described above. It is applied independently to the element 106 and the sixth DC / DC converter 121 to control the output timing of the ON signal. That is, the occurrence of the system down is prevented by providing a sequence for the ON output of the first ON / OFF signal and the second ON / OFF signal.

  FIG. 6 is a timing chart showing a rising sequence of the A output, the B output, the C output, the first on / off signal, and the second on / off signal shown in FIG. As can be seen from this timing chart, the output A rises when the DC power supply 120 is turned on. Next, the second ON signal is input from the control device 13, the sixth DC / DC converter 121 is driven, and power is supplied to the first load 7. Thereafter, the first ON signal is input, whereby the switching element 106 is turned ON, the relay and the power factor correction circuit 103 operate in this order, the B output and the C output rise, and the second load 8 and the third output Power is supplied to the load 9.

  The output sequence of the first and second on / off signals in the third embodiment is a sequence in which the second on signal is given earlier than the first on signal as shown in FIG. By always realizing this sequence, the system down can be prevented.

  Other parts that are not particularly described are configured in the same manner as in the first embodiment and function in the same manner, and thus redundant description is omitted.

  FIG. 7 is a block diagram showing a configuration of a DC power supply apparatus according to Embodiment 4 of the present invention. The DC power supply device 130 according to the fourth embodiment is an example in which the sequence of the third embodiment is realized by one on / off signal. In the fourth embodiment, a timer IC 131 is provided with respect to the third embodiment, and the on / off signal is one system. That is, as shown in FIG. 7, an on / off signal is input in series to the second DC / DC converter 104 and the sixth DC / DC converter 121, while the switch element 106 is switched through a predetermined delay time by the timer IC 131. It is turned on / off.

  Thus, in the fourth embodiment shown in FIG. 7, the first DC / DC converter 102 is driven via the signal that inputs one on / off signal directly to the sixth DC / DC converter 121 and the timer IC 131. The DC power supply device 130 can be driven by branching into two signals (corresponding to the first on / off signal). Therefore, in this embodiment, each DC / DC converter can be driven by one signal in the sequence shown in the timing chart of FIG.

  Other parts that are not particularly described are configured in the same manner as in the first embodiment and function in the same manner, and thus redundant description is omitted.

  FIG. 8 is a block diagram showing a configuration of a DC power supply apparatus according to Embodiment 5 of the present invention. The DC power supply device 140 according to the fifth embodiment is a time constant circuit 141 that forms a similar time difference instead of the timer IC 131 in the DC power supply device 130 according to the fourth embodiment. Other parts are configured in the same manner as in the fourth embodiment and function in the same manner.

  FIG. 9 is a block diagram showing a configuration of a DC power supply apparatus according to Embodiment 6 of the present invention. In the DC power supply device 120 according to the third embodiment, energy saving can be achieved, but the rise time of the B output and the C output cannot be increased. In this embodiment, the power consumption and the rise time in the energy saving mode can be increased. In other words, this embodiment is a combination of the configurations of the second and third embodiments, and the sixth DC / DC converter 121 is connected in parallel to the first DC / DC converter 102 in the configuration of the second embodiment. The first on / off signal can be input to the switching element 106 and the second on / off signal can be input to the fourth DC / DC converter 111 and the sixth DC / DC converter, respectively.

  Thereby, the B output and the C output necessary at the time of initial startup are output from the fourth DC / DC converter 111 and the fifth DC / DC converter 112. Further, by inputting an ON signal with the second ON / OFF signal to the fourth DC / DC converter 111 and the sixth DC / DC converter 121, the DC power supply device 150 returns from the energy saving mode. Thereafter, an ON signal is input as the first ON / OFF signal to turn on the switch element 106. As a result, the power factor correction circuit 103 operates to output the B output and the C output from the second DC / DC converter 104 and the third DC / DC converter 105, and the second load 8 and the third load 9. Each is supplied with power.

  FIG. 10 is a timing chart showing the rising sequence associated with the ON signal output of the A output, B output, C output and ON / OFF signal of FIG. As can be seen from the timing chart of FIG. 10, the output A rises after the DC power supply device 150 is turned on. Thereafter, the fourth DC / DC converter 111 and the sixth DC / DC converter 121 are driven by the ON signal of the second ON / OFF signal, and the output of the fourth DC / DC converter 111 is connected to the second load 8 and the second load. 5 DC / DC converter 112, and the fifth DC / DC converter 112 outputs the third load 9. Then, the switching element 106 is turned on by the ON signal of the first ON / OFF signal, and is output from the second DC / DC converter 104 and the third DC / DC converter 105 via the power factor correction circuit 103, and B And the output from the fourth and fifth DC / DC converters 111 and 112 are combined as the C output, and a current is applied to the second and third loads 8 and 9.

  During this time, since the necessary current is supplied to the first load by the sixth DC / DC converter 121, there is no possibility that the system stops when returning from the energy saving state.

It is a block diagram which shows the structure of the direct-current power supply device which concerns on Example 1 of this invention. It is a timing chart which shows the rising sequence of each output and ON / OFF signal of FIG. 2 is a timing chart showing a rising sequence when the switching element of FIG. 1 is changed to an FET switch. FIG. 6 is a block diagram illustrating a configuration of a DC power supply device according to a second embodiment. FIG. 6 is a block diagram illustrating a configuration of a DC power supply device according to a third embodiment. 6 is a timing chart showing a rising sequence of each output and two on / off signals in FIG. 5. FIG. 10 is a block diagram illustrating a configuration of a DC power supply device according to a fourth embodiment. FIG. 10 is a block diagram illustrating a configuration of a DC power supply device according to a fifth embodiment. FIG. 10 is a block diagram illustrating a configuration of a DC power supply device according to a sixth embodiment. 10 is a timing chart showing a rising sequence of each output and two on / off signals in FIG. 9. It is a block diagram which shows an example of a structure of the conventional DC power supply device. 1 is a block diagram illustrating a schematic configuration of an image forming apparatus.

Explanation of symbols

7 First load 8 Second load 9 Third load 10 AC power supply 11 Mechatronic component 12 Sensor 13 Control device 14 Scanner / writing device 15 Conveying / paper feeding device
DESCRIPTION OF SYMBOLS 101 Rectification circuit 102 1st DC / DC converter 103 Power factor improvement circuit 104 2nd DC / DC converter 105 3rd DC / DC converter 111 4th DC / DC converter 112 5th DC / DC converter 121 1st 6 DC / DC converter 106 Switching element 131 Timer IC
141 Time constant circuit

Claims (9)

A rectifier circuit for rectifying an AC voltage input from the AC power source, provided in parallel downstream of the pre-Symbol rectifier circuit, a plurality of D C / DC converter for outputting the rectified AC voltage in the rectifier circuit smoothes , set in parallel downstream of the pre-Symbol rectifier circuit vignetting, and power factor improvement circuit for improving the power factor of the rectified AC voltage, provided between the rectifier circuit and the power factor correction circuit, the energy-saving mode In a DC power supply device comprising switch means that sometimes deactivates the power factor correction circuit ,
The plurality of DC / DC converters each output the same potential, and are provided at a subsequent stage of the rectifier circuit and always output even in the energy saving mode, and the power factor correction circuit A second DC / DC converter which is provided in a subsequent stage and outputs when not in the energy saving mode but not in the energy saving mode, and the power factor improving circuit is operated by the ON operation of the switch means, so that the second Another DC / DC converter that supplies a necessary current until the DC / DC converter outputs, and another DC that smoothes the output of the rectifier circuit and supplies it to the output side of the first DC / DC converter At least one of the DC / DC converters,
The first DC / DC converter monitors the case where the output current that can be supplied by the second DC / DC converter is exceeded by the control means connected to the outside, and receives the switching signal issued from the switch means. A DC power supply circuit characterized in that auxiliary output is provided by control . In the DC power supply device according to claim 1, wherein the switching means, the dc power supply you characterized by comprising a relay or FET. 3. The direct-current power supply device according to claim 1, wherein the plurality of DC / DC converters each have an output side connected to a load, and the first DC / DC converter and the second DC / DC controlled by the switch means. converter switching between the dc power supply you characterized in that by being performed based on the mode switching of the load said control means. 3. The DC power supply device according to claim 1, wherein switching between the first DC / DC converter and the second DC / DC converter by the control of the switch means is performed on the current value detected by the control means. based on direct current power supply you characterized by being performed. 5. The DC power supply device according to claim 1, wherein the another DC / DC converter switches a signal different from the switching signal for controlling the switch means generated by the control means. 6. dc power supply you characterized in that operate by receiving signals are on-off control. In the DC power supply device according to claim 5, wherein said switching signal for controlling said switching means, said further signal dc power supply you characterized in that it is outputted to have a time difference relative to the switching signal . In the DC power supply device according to claim 6, dc power supply you comprising the timer or the time constant circuit for setting the time difference. In the DC power supply device according to claim 5, wherein the other DC / DC converter, dc power supply you characterized in that operation by the switching signal of the further signal is on-off control. An image forming apparatus comprising the DC power supply device according to claim 1.

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