JP2014043098A - Power supply device, electronic equipment and system - Google Patents

Abstract

A power supply device, an electronic apparatus, and a system capable of improving the efficiency of a power supply are provided.
A power supply control unit 160 includes a constant voltage power supply 161, one or more constant current power supplies (162, 163), a current detection unit 164, and a control unit 165. The constant voltage power supply 161 performs constant voltage output. The constant current power supplies (162, 163) perform constant current output. The current detection unit 164 is provided at a stage subsequent to the junction point Z where the first current output from the constant voltage power supply 161 and the second current output from the constant current power supply merge, and the current supplied to the load 400 is To detect. The control unit 165 controls the supply and stop of the second current to the load 400 according to the current detected by the current detection unit 164.
[Selection] Figure 3

Description

  The present invention relates to a power supply device, an electronic apparatus, and a system.

  For example, an electrophotographic image forming apparatus has various functions such as a printer, a copy, and a FAX, and consumes a large amount of power. For this reason, there has been conventionally known a method in which the output of a constant current DC power source that is operated by a storage battery that is a constant voltage DC power source and a power source from an AC line is joined to increase the maximum output power.

  For example, Patent Document 1 discloses a technique for joining an output from a storage battery, which is a constant voltage DC power supply, and an output from a constant current DC power supply for the purpose of increasing the maximum output power.

  However, since the efficiency of the power supply varies greatly depending on the usage rate, the technique disclosed in Patent Document 1 has a problem that power consumption at a light load increases.

  The present invention has been made in view of the above, and an object thereof is to provide a power supply device, an electronic apparatus, and a system that can improve the efficiency of a power supply.

  In order to solve the above-described problems and achieve the object, the present invention is a power supply device for controlling a current supplied to a load, a constant-voltage power supply that outputs a first current of a constant voltage, One or more constant current power supplies for outputting a second current, at least a current detection section for detecting a first current output from the constant voltage power supply, and the load according to the current detected by the current detection section And a controller for controlling the supply and stop of the second current to.

  In addition, the present invention is an electronic device including the above-described power supply device. Furthermore, the present invention is a system including at least an electronic device, wherein the electronic device includes a constant voltage power source that outputs a first current having a constant voltage and one or more that outputs a second current having a constant current. A constant current power supply; and a current detection unit that detects at least a first current output from the constant voltage power supply, wherein the system detects the second current with respect to a load according to the current detected by the current detection unit. A control unit for controlling supply and stop of current is provided.

  According to the present invention, there is an advantageous effect that the efficiency of the power source can be improved.

FIG. 1 is a diagram illustrating a configuration example of an image forming system according to an embodiment. FIG. 2 is a block diagram illustrating a hardware configuration example of the image forming system according to the embodiment. FIG. 3 is a diagram illustrating a configuration example of the power control unit according to the embodiment. FIG. 4 is a diagram illustrating an example of the efficiency of the power supply with respect to the current usage rate for each of the constant voltage power supply and the constant current power supply used in the embodiment. FIG. 5 is a diagram schematically illustrating an example of the relationship between the total current and the breakdown of the current output from each power source. FIG. 6 is a flowchart illustrating an example of a processing operation performed by the control unit of the power supply control unit. FIG. 7 is a diagram showing a comparative example of the efficiency when a constant voltage power source and a constant current power source are combined with the efficiency when only a single power source is used. FIG. 8 is a diagram schematically illustrating an example of the relationship between the total current and the breakdown of the current output from each power source. FIG. 9 is a diagram illustrating an example of a change in the total current with time. FIG. 10 is a diagram schematically illustrating an example of the relationship between the total current and the breakdown of the current output from each power source. FIG. 11 is a diagram showing a comparative example of the efficiency when the current output from the constant current power source is fixed and the efficiency when the current output from the constant current power source is variably set. FIG. 12 is a diagram illustrating a configuration example of a power control unit according to a modification. FIG. 13 is a diagram illustrating a state in which the efficiency between the constant current power sources is different. FIG. 14 is a diagram illustrating a configuration example of a power control unit according to a modification. FIG. 15 is a diagram schematically illustrating an example of the relationship between the total current and the breakdown of the current output from each power source in the modified example. FIG. 16 is a diagram illustrating an example of the efficiency table. FIG. 17 is a diagram illustrating an operation flow of the control unit according to the modification. FIG. 18 is a diagram illustrating a state in which the efficiency of the constant current power source is changed according to use conditions. FIG. 19 is a diagram illustrating an example of the efficiency table. FIG. 20 is a diagram schematically illustrating an example of the relationship between the total current and the breakdown of current output from each power source in the modification. FIG. 21 is a diagram illustrating a configuration example of a power supply control unit according to a modification.

  Hereinafter, embodiments of a power supply device, an electronic device, and a system according to the present invention will be described in detail with reference to the accompanying drawings. In each of the following embodiments, as an electronic device, an image forming apparatus having a function of forming an image on a recording medium will be described as an example. However, the present invention is not limited to this, and the types of electronic devices are Is optional. For example, a digital camera, a mobile phone, a PC, or the like can be employed as the electronic device.

(First embodiment)
FIG. 1 is an external view illustrating an example of an image forming system 100 according to the first embodiment. The image forming system 100 is a production printing machine and includes an external controller 200 (hereinafter referred to as “DFE 200”). The image forming system 100 includes an image forming apparatus 110 that includes a large-capacity paper feeding unit 102 that feeds paper, an inserter 103 that is used to use a cover, a folding unit 104 that performs folding, a finisher 105 that performs stapling and punching, and the like. Peripheral machines such as a cutting machine 106 for cutting are combined in accordance with the application.

  FIG. 2 is a diagram illustrating a hardware configuration example of the image forming system 100. As shown in FIG. 2, the DFE 200 includes a communication I / F unit 210, an image processing unit 220, a CPU 230, a storage unit 240 (HDD 242, ROM 244, RAM 246), and an I / F unit 250. The buses B1 are connected to each other. The communication I / F unit 210 can communicate with a host device such as a PC via a network (communication network) such as the Internet. For example, the communication I / F unit 210 can receive image data (image data described in page description language (PDL)) transmitted from the host device.

  The image processing unit 220 interprets the image data received from the host device via the communication I / F unit 210 and converts the image data into image data in a format printable by the image forming apparatus 110. In addition, the image processing unit 220 performs predetermined processing (gamma correction or the like) on the converted image data. The CPU 230 comprehensively controls the operation of the image forming system 100 by developing and executing a program stored in the ROM 244 or the like on the RAM 246.

  The I / F unit 250 is a means for connecting the DFE 200 to the image forming apparatus 110, and the dedicated line 30 is connected to the I / F unit 250. In the example of FIG. 2, in order to secure the communication speed, the DFE 200 exemplifies a configuration that is connected to the image forming apparatus 110 through the dedicated line 30. The configuration may be such that the DFE 200 and the image forming apparatus 110 are connected to each other.

  As shown in FIG. 2, the image forming apparatus 110 includes an I / F unit 120, a printing unit 130, another I / F unit 140, an operation display unit 150, and a power supply control unit 160, each of which is a bus. Connected at B2. The I / F unit 120 is means for connecting the image forming apparatus 110 to the DFE 200, and the dedicated line 30 is connected to the I / F unit 120. The printing unit 130 is a unit that forms an image on a recording medium such as transfer paper. The printing unit 130 executes a print job under the control of the CPU 230 of the DFE 200. The other I / F unit 140 is an interface capable of connecting an external device or the like, for example. The operation display unit 150 is a unit that displays the operation status and state of the image forming apparatus 110 and receives an operation input from the user.

  FIG. 3 is a diagram illustrating a configuration example of the power control unit 160 provided in the image forming apparatus 110. The power supply control unit 160 is a unit that converts AC power supplied from an AC power supply 300 such as a commercial power supply into DC power and controls the DC power supplied to the load 400 in the image forming apparatus 110. Examples of the load 400 include a semiconductor, a motor, and a fan, but are not limited thereto. As shown in FIG. 3, the power supply control unit 160 includes a constant voltage power supply 161, a first constant current power supply 162, a second constant current power supply 163, a current detection unit 164, and a control unit 165. The power control unit 160 of the present embodiment corresponds to “power supply device” in the claims. However, the present invention is not limited thereto, and for example, a portion including the power supply control unit 160 and the AC power supply 300 can be regarded as a “power supply device” in the claims.

  In this example, two constant current power supplies are combined with one constant voltage power supply, but the present invention is not limited to this, and the number of constant current power supplies combined with the constant voltage power supply is arbitrary. Any configuration may be used as long as at least one constant current power source is combined. FIG. 4 is a diagram illustrating an example of the efficiency of the power supply with respect to the current usage rate for each of the constant voltage power supply and the constant current power supply used in the present embodiment. Here, the efficiency of the power supply is determined by the rated voltage, the load condition, and the requirement for increasing the efficiency under what conditions. It is difficult to make a perfect product under all conditions, which is a trade-off between the above conditions. In this embodiment, since the constant voltage power supply is used under all conditions from 0 to 100% of load, a power supply with uniform efficiency is used even if the peak value of efficiency is low. Since the constant current power supply is basically used under the condition of the best efficiency, the efficiency is low when the usage rate is low, and the power supply with high efficiency is used only under a very narrow condition where the usage rate is high. In the example of FIG. 4, the efficiency of the constant voltage power source is 70 to 80% over the entire current usage rate, and the efficiency of the constant current power source varies from 40 to 90%, but the current usage rate is 90%. In some cases, the efficiency is as high as 90%.

  Returning to FIG. 3 again, the description will be continued. The constant voltage power supply 161 converts AC power from the AC power supply 300 into DC power, holds the output voltage constant, and outputs the converted DC power (performs constant voltage output). In this example, the constant voltage power supply 161 can output from 0A to 7A.

  The first constant current power supply 162 and the second constant current power supply 163 convert AC power from the AC power supply 300 into DC power, hold the output current constant, and output the converted DC power (constant current). Output). In this example, the first constant current power supply 162 and the second constant current power supply 163 have the highest efficiency when the output current is 5 A, and the first constant current power supply 162 and the second constant current power supply 163 respectively. Is basically fixed at 5A. Note that this is an example, and the output current (second current) of the constant current power supply may be any value as long as the efficiency of the constant current power supply exceeds the efficiency of the constant voltage power supply. It can be set.

  Output currents from each of the constant voltage power supply 161, the first constant current power supply 162, and the second constant current power supply 163 are merged at the merge point Z, and the merged current is supplied to the load 400. In the following description, the current output from the constant voltage power supply 161 is referred to as a first current, and the current output from each of the first constant current power supply 162 and the second constant current power supply 163 is referred to as a second current. Sometimes called.

  In FIG. 3, the current detection unit 164 is provided after the junction point Z. More specifically, the current detection unit 164 is provided on a current path from the junction point Z to the load 400. The current detection unit 164 is means for detecting a current supplied to the load 400. The configuration of the current detection unit 164 may take various configurations of known current detection means, but may be configured to detect current using, for example, a resistor and a current detection amplifier.

  The control unit 165 controls the supply and stop of the second current to the load 400 according to the current detected by the current detection unit 164. More specifically, it is as follows. As shown in FIG. 3, whether to supply AC power to the first constant current power supply 162 is switched between the input side of the first constant current power supply 162 and the AC power supply 300 according to control by the control unit 165. A first switch SW1 is provided. Further, between the input side of the second constant current power source 163 and the AC power source 300, a second switch SW2 for switching whether or not to supply AC power to the second constant current power source 163 is controlled according to control by the control unit 165. Is provided. The control unit 165 controls the supply and stop of the second current to the load 400 by switching the first switch SW1 and the second switch SW2. Here, the first switch SW1 and the second switch SW2 correspond to a “switching unit” in the claims. The first switch SW1 and the second switch SW2 are not particularly limited as long as they are elements capable of switching on and off of current, such as relays and FETs. The control unit 165 individually controls on / off of the first switch SW1 and the second switch SW2 according to the current detected by the current detection unit 164. Details will be described below.

  FIG. 5 shows a current that merges at the merge point Z (hereinafter sometimes referred to as “total current”) and each power source (constant voltage power source 161, first constant current power source 162, second constant current power source 163). It is a figure which shows typically an example of the relationship with the breakdown of the electric current output from. A region P1 shown in FIG. 5 shows a region where the first current from the constant voltage power supply 161 is output, and a region P2 shown in FIG. 5 shows the second current from the first constant current power supply 162 (fixed at 5A). The region P3 shown in FIG. 5 indicates a region where the second current (fixed at 5A) from the second constant current power source 163 is output.

  As shown in FIG. 5, when the current (total current) detected by the current detection unit 164 is 6 A or less, the control unit 165 operates only the constant voltage power supply 161, and the first switch SW1 and the second switch Each of SW2 is controlled to be off.

  When the total current detected by the current detection unit 164 exceeds 6A and is 11A or less, the control unit 165 controls the first switch SW1 to be on and the second switch SW2 to be off. To do. As a result, the second current (5A) output from the first constant current power supply 162 flows into the junction Z. When the total current is 6A to 11A, the second current output from the first constant current power supply 162 is fixed to 5A, while the first current output from the constant voltage power supply 161 changes to 1A to 6A. Absorb fluctuations.

  Further, when the total current detected by the current detection unit 164 exceeds 11 A, the control unit 165 controls each of the first switch SW1 and the second switch SW2 to be turned on. As a result, the second current (5A) output from each of the first constant current power supply 162 and the second constant current power supply 163 flows into the junction Z. That is, the total of the second current supplied from the constant current power source to the junction Z is 10A. When the total current exceeds 11 A, the second current output from each of the first constant current power supply 162 and the second constant current power supply 163 is fixed to 5 A, while the first current output from the constant voltage power supply 161 is used. The current changes to a value obtained by subtracting 10 A from the total current, and absorbs the fluctuation.

  In the example of FIG. 5, the reason why the on / off switching condition of the first switch SW1 is set to 6A and the on / off switching condition of the second switch SW2 is set to 11A is the supply capability of the constant voltage power supply 161 capable of outputting up to 7A. This is because a margin of 1 A is provided to cope with a sudden increase in current. For example, when only the constant voltage power supply 161 is operated, a total current of 0 to 7 A can be supplied to the load 400, and the constant voltage power supply 161 and the first constant current power supply 162 are operating. Can supply a total current of 6 A to 12 A to the load 400.

  Next, an example of processing operation by the control unit 165 will be described with reference to FIG. FIG. 6 is a flowchart illustrating an example of a processing operation performed by the control unit 165. Note that when the image forming apparatus 110 main body is activated, since the exact value of the required current (current required by the load 400) is unknown, the control unit 165 performs control to activate only the constant voltage power supply 161. On the other hand, control for switching on and off the first switch SW1 and the second switch SW2 is not performed. At this time, each of the first switch SW1 and the second switch SW2 is controlled to be in an off state. Further, after starting the main body, all the loads 400 are not started up until the current is measured, but the loads 400 are started up within a range that can be covered by the first current output from the constant voltage power supply 161.

  As shown in FIG. 6, first, the control unit 165 acquires the current (total current) detected by the current detection unit 164 (step S1). Next, the control unit 165 determines whether or not the current acquired in step S1 is smaller than 6A, which is an on / off switching condition of the first switch SW1 (step S2). When it is determined that the current acquired in step S1 is smaller than 6 A (result of step S2: YES), the control unit 165 operates only the constant voltage power supply 161 (step S3). More specifically, the control unit 165 controls the first switch SW1 and the second switch SW2 to be turned off, and performs control to operate only the constant voltage power supply 161 so that the current detected by the current detection unit 164 can be obtained. .

  On the other hand, when it is determined that the current acquired in step S1 is 6A or more (result of step S2: NO), the control unit 165 determines whether or not the current acquired in step S1 is smaller than 11A ( Step S4). When it is determined that the current acquired in step S1 is smaller than 11 A (result of step S4: YES), the control unit 165 operates the constant voltage power supply 161, turns on the first switch SW1, and turns on the second switch SW2. Is turned off (step S5). In Step S4 described above, when it is determined that the current acquired in Step S1 is 11 A or more (result of Step S4: NO), the control unit 165 operates the constant voltage power supply 161 and first Each of the switch SW1 and the second switch SW2 is controlled to be on (step S6). The control unit 165 repeatedly executes the above operation at a predetermined cycle.

  As described above, in the present embodiment, the control unit 165 is output from each of the first constant current power supply 162 and the second constant current power supply 163 according to the current detected by the current detection unit 164. ON / OFF of the second current (supply and stop of the second current to the load 400) is controlled. The second current output from the constant current power supply (the first constant current power supply 162 and the second constant current power supply 163) is fixed to a value with the highest efficiency (5A in this example). As shown in FIG. 3, the present invention has an advantageous effect that the efficiency can be improved over the entire region of the current (current supplied to the load 400) as compared with the configuration in which only a single power source (for example, constant voltage power source) is operated. In particular, when the range of current supplied to the load 400 is 6A to 11A, the configuration of this embodiment (a configuration combining a constant voltage power source and a constant current power source) uses a constant current power source having higher efficiency than the constant voltage power source. Since it is operated, the overall efficiency is also increased. In addition, as understood from FIG. 7, when the ratio of the current output from the constant current power supply to the load 400 is high (current supplied to the load 400 is around 6A and 11A), It turns out that efficiency becomes high.

  In FIG. 3, the current detection unit 164 is provided at the subsequent stage of the junction point Z. However, the current detection unit 164 is provided as a plurality of current detection units at the upstream stage of the junction point Z, and the constant voltage power source is provided. The output current of 161, the output current of the constant current power supply 162, and the output current of the constant current power supply 163 may be detected. In this case, the current supplied to the load 400 can be detected by adding the output current of the constant voltage power supply 161, the output current of the constant current power supply 162, and the output current of the constant current power supply 163. As another method, since the constant current power supply outputs a constant current, the current detection unit 164 is provided at a position where the output of the constant voltage power supply 161 before the junction Z is detected, and the current output from the constant voltage power supply 161 is It may be detected only. In this case, the output current of the constant voltage power supply 161 detected by the current detection unit 164 is added to the output currents of the constant current power supply 162 and the constant current power supply 163 based on the ON state of the first switch SW1 and the second switch SW2. Thus, the current supplied to the load 400 can be detected.

  In FIG. 3, the constant current power source 162 and the constant current power source 162 are switched on and off by turning on and off the first switch SW1 that switches the current input to the constant current power source 162 and the second switch SW2 that switches the current input to the constant current power source 163. Although the output of 163 is turned on and off, the operation of the constant current power supply itself may be stopped. For example, when the constant current power supply is a switching power supply, a method of stopping the switching can be considered.

(Second Embodiment)
Next, a second embodiment will be described. In the second embodiment, when the on / off condition of the second current output from the constant current power supply is turned on (when the supply of the second current to the load 400 is started), the second current is turned off. It differs from the above-mentioned 1st Embodiment by the point made to differ by the case where it supplies (when supply of a 2nd electric current is stopped with respect to the load 400). This will be specifically described below. In addition, about the part which is common in the above-mentioned 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted suitably.

  FIG. 8 shows the current (total current) that joins at the junction Z and the power sources (constant voltage power source 161, first constant current power source 162, and second constant current power source 163) in this embodiment. It is a figure which shows an example of a relationship with the breakdown of an electric current typically. A region P11 shown in FIG. 8 shows a region where the first current from the constant voltage power supply 161 is output, and a region P22 shown in FIG. 8 shows the second current from the first constant current power supply 162 (fixed at 5A). Is output, and a region P33 illustrated in FIG. 8 indicates a region where the second current (fixed at 5A) from the second constant current power supply 163 is output.

  As illustrated in FIG. 8, the control unit 165 causes the first switch SW <b> 1 to be turned on when the current (total current) detected by the current detection unit 164 exceeds 6.25 A. That is, in the example of FIG. 8, the condition for turning on the first switch SW1 (the condition for starting the supply of the second current from the first constant current power supply 162 to the load 400) is the current detection unit. The current detected at 164 exceeds 6.25A.

  On the other hand, when the current (total current) detected by the current detection unit 164 is less than 5.75 A, the control unit 165 shifts the first switch SW1 to OFF. That is, in the example of FIG. 8, the condition for turning off the first switch SW1 (the condition that the supply of the second current from the first constant current power supply 162 to the load 400 is stopped) is the current detection unit. The current detected at 164 is below 5.75A.

  In addition, as illustrated in FIG. 8, when the current (total current) detected by the current detection unit 164 exceeds 11.25 A, the control unit 165 transitions the second switch SW2 to ON. That is, in the example of FIG. 8, the condition for turning on the second switch SW2 (the condition for starting the supply of the second current from the second constant current power source 163 to the load 400) is the current detection unit. The current detected at 164 exceeds 11.25A.

  On the other hand, when the current (total current) detected by the current detection unit 164 is less than 10.75A, the control unit 165 transitions the second switch SW2 to OFF. That is, in the example of FIG. 8, the condition for turning off the second switch SW2 (the condition that the supply of the second current from the second constant current power supply 163 to the load 400 is stopped) is the current detection unit. The current detected at 164 is below 10.75A.

  As described above, in the present embodiment, the total current (6.25 A) set as a condition for transitioning the first switch SW1 to ON and the total current (5.75 A) set as a condition for transitioning OFF. ) Is provided with a hysteresis of 0.5 A. In addition, a hysteresis of 0.5 A between a total current (11.25 A) set as a condition for transitioning the second switch SW2 to ON and a total current (10.75 A) set as a condition for transitioning to OFF Is provided.

  For example, as in the first embodiment described above, for each of the first switch SW1 and the second switch SW2, a total current set as a condition for transitioning on and a total current set as a condition for transitioning off If they are the same (6A, 11A), when the total current of 6A or near 11A continues to be supplied to the load 400, the first switch SW1 or the second switch SW2 is frequently turned on and off. Considering the power required for starting up the constant current power source and the life of the switch (relay), it is not preferable to turn on / off too frequently. Therefore, in the second embodiment, for each of the first switch SW1 and the second switch SW2, 0 is between the total current set as a condition for transitioning on and the total current set as a condition for transitioning off. By providing a hysteresis of .5A, the frequency of switching can be suppressed.

  The hysteresis value is not limited to 0.5 A, and can be arbitrarily set. That is, the total current set as a condition for turning on the second current (condition for starting the supply of the second current output from the constant current power supply to the load 400) and a condition for turning off (load) The total current value set as a condition for stopping the supply of the second current output from the constant current power source with respect to 400 may be different. In short, when the current (total current) detected by the current detection unit 164 is greater than or equal to the first threshold, the control unit 165 performs control to start supplying the second current to the load 400, while the current detection unit 164 In the case where the detected current is equal to or less than the second threshold value different from the first threshold value, any function may be used as long as it has a function of controlling the supply of the second current to the load 400. In the second embodiment, the case where the first threshold value is set to a value larger than the second threshold value is exemplified. However, the present invention is not limited to this. For example, the first threshold value is set to a value smaller than the second threshold value. Also good.

(Third embodiment)
Next, a third embodiment will be described. The third embodiment is different from the above-described embodiments in that the control unit 165 determines whether or not the second current can be supplied to the load 400 for each operation state of the image forming apparatus 110. This will be specifically described below. In addition, about the part which is common in each above-mentioned embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted suitably.

  For example, in the first embodiment described above, when the second current output from the constant current power supply is turned off by instantaneously decreasing the current (total current) at the timing when the load 400 does not operate during printing. Is also envisaged. In this case, if the operation of the load 400 is started immediately after that, it is difficult to immediately turn on the second current, and thus it becomes difficult to supply a necessary current to the load 400.

  In the example of FIG. 9, the state in which current supply to the load 400 is performed only by the constant voltage power supply 161 is P1, and the state in which current supply is performed by the combination of the constant voltage power supply 161 and the first constant current power supply 162 is P1 + P2. A state in which current is supplied by a combination of the voltage power supply 161, the first constant current power supply 162, and the second constant current power supply 163 is denoted as P1 + P2 + P3, respectively. In the example of FIG. 9, until the total current temporarily falls below 6A, current is supplied by the combination of the constant voltage power supply 161 and the first constant current power supply 162, but the total current is temporarily When the current falls below 6A, the first switch SW1 is turned off as described above, and the second current output from the first constant current power supply 162 is turned off. Therefore, only the constant voltage power supply 161 operates to supply current. However, even if the total current increases immediately after that, even if a current exceeding 6 A is required, a certain amount of time is required until the first constant current power supply 162 starts up. Can not be performed.

  Therefore, in the present embodiment, not only the current value detected by the current detection unit 164 but also the operation state (mode) of the image forming apparatus 110 is taken into account, and the second current is turned on / off for each operation mode. In the present embodiment, the determination of the on / off state of the second current based on the mode has priority over the determination of the on / off state of the second current based on the total current. For example, a table in which a mode and a combination of power sources are associated is stored in a memory (not shown), and the control unit 165 reads the combination of power sources corresponding to the current mode from the memory, and supplies current with the read combination of power sources. It can also be controlled to do.

  For example, when the combination of the power supplies corresponding to the normal printing mode is a combination of the constant voltage power supply 161 and the first constant current power supply 162, the control unit 165 supplies the constant voltage power supply so as to supply current with the combination. 161 is operated, and the first switch SW1 is turned on and the second switch SW2 is turned off. Therefore, as long as the normal printing mode is selected, current is supplied by the combination of the constant voltage power supply 161 and the first constant current power supply 162. Therefore, even if the total current temporarily falls below 6A as shown in FIG. Since the second current output from the first constant current power supply 162 does not transit to OFF, a situation in which the load 400 cannot temporarily perform a desired operation can be avoided.

(Fourth embodiment)
Next, a fourth embodiment will be described. The fourth embodiment is different from the above-described embodiments in that the value of the second current described above can be set variably. This will be specifically described below. In addition, about the part which is common in each above-mentioned embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted suitably.

  In the first embodiment described above, the second current output from the constant current power source is fixed at 5A, which is the most efficient. However, the constant current power source is more efficient than the constant voltage power source even in the vicinity of 4A, for example. Therefore, in the fourth embodiment, as illustrated in FIG. 10, when the total current detected by the current detection unit 164 is 5 A, the control unit 165 shifts the first switch SW1 to ON (first As a breakdown of the total current 5A, the second current output from the first constant current power supply 162 is controlled to 4A, and the first current output from the constant voltage power supply 161 is controlled to 1A. Thereafter, the control unit 165 linearly increases the second current output from the first constant current power supply 162 in the range where the total current is from 5A to 6A.

  Similarly, when the total current detected by the current detection unit 164 is 10 A, the second switch SW2 is turned on (the second constant current power source 163 is turned on), and the breakdown of the total current 10A is as follows. The second current output from the constant current power supply 162 is controlled to 5A, the second current output from the second constant current power supply 163 is controlled to 4A, and the first current output from the constant voltage power supply 161 is controlled to 1A. Thereafter, the control unit 165 linearly increases the second current output from the second constant current power source 163 in the range where the total current is 10A to 11A.

  As described above, an energy saving effect can be obtained by using the constant current power supply in a region where the efficiency of the constant current power supply exceeds the efficiency of the constant voltage power supply. FIG. 11 shows the efficiency when the second current output from the constant current power supply is fixed and the efficiency when the second current output from the constant current power supply is variably set (efficiency in the case of FIG. 10). It is a figure which shows a comparative example. As described above, in the fourth embodiment, the first constant current power supply 162 is started up when the total current is 5 A, and the second constant current power supply 163 is started up when the total current is 10 A. That is, since each of the first constant current power supply 162 and the second constant current power supply 163 is started up by 1 A earlier than the first embodiment, the efficiency in the vicinity thereof is the same as that of the first embodiment. Compared to the case has been improved. In this example, the region from 4 to 5 A of the current output from the constant current power source is used. However, the present invention is not limited to this, and the region where the constant current power source is started up at 4 A or less can improve the efficiency. It is also possible to use an area of 5A or more.

(Modification)
As mentioned above, although embodiment of this invention was described, this invention is not limited to each above-mentioned embodiment, A various deformation | transformation is possible within the range which does not deviate from the summary of this invention.

(1) Modification 1
In each of the above-described embodiments, the power source configuration is fixed (constant voltage power source 161, first constant current power source 162, second constant current power source 163), but is not limited thereto, and for example, the power source configuration is variable. There may be. For example, it may be assumed that the current required for the main body of the image forming apparatus 110 increases due to attachment of an option or the like. Here, since there is one current path from the junction point Z to the load 400, it is easy to expand or add a power source. For example, it is possible to increase or decrease the number of constant current power supplies by preparing in advance a switch (relay) or the like for switching whether or not to supply AC power from the AC power supply 300 to the constant current power supply to be added (FIG. 12). reference). For this reason, the power supply configuration can always be optimized, and energy saving and function expansion are easy to perform. It is also easy to replace the current power supply when a more efficient power supply is developed several years after the delivery of the machine.

  Further, as shown in FIG. 12, by further including a temperature detection unit 166 capable of detecting the environmental temperature, the control unit 165 can switch on / off of the second current in consideration of an efficiency change due to temperature. is there. This is because the efficiency curve changes because the characteristics of the transformer, capacitor, and the like change depending on the temperature. In addition, it enables control of power supply enable / disable. In each of the embodiments described above, the switch SW is provided between the AC power supply 300 and the input side of the constant current power supply. However, considering the life of the relay and the power-on time, it is desirable to suppress the frequency of switching. Therefore, it is possible to control the output side of the constant current power supply so that it is not output. For example, a semiconductor element such as an FET or a triac may be used so that the load 400 can be disconnected. Since there is a fixed loss of the power supply, the efficiency is worse than when the input side of the constant current power supply is cut off. However, when the frequency of switching is high, the form in which the output side of the constant current power supply is disconnected from the load 400 is better. preferable. In addition, for example, the input side can be switched to a state where the input side is blocked depending on the elapse of a certain time or the mode.

(2) Modification 2
In each of the above-described embodiments, an example in which the power supply control unit 160 is mounted on the image forming apparatus 110 has been described. However, the present invention is not limited to this. For example, the control unit 165 that is one of the elements constituting the power supply control unit 160. May be mounted on the DFE 200. In short, a system (for example, an image forming system) to which the present invention is applied includes at least an electronic device (for example, an image forming apparatus), and the electronic device includes a constant voltage power source, one or more constant current power sources, and a constant voltage power source. A current detection unit that is provided at a stage subsequent to a junction where the first current that is output and the second current that is output from the constant current power source are combined, and that detects the current supplied to the load. Any control unit that controls the supply and stop of the second current to the load according to the current detected by the current detection unit may be used.

(3) Modification 3
Unlike the above-described embodiments, for example, the DFE 200 as an external server may not be provided, and the function of the above-described DFE 200 may be mounted on the image forming apparatus 110.

(4) Modification 4
In each of the above-described embodiments, the image forming apparatus has been described as an example of an electronic device in which the power control unit 160 is mounted. However, the present invention is not limited to this, and the type of electronic device in which the power control unit 160 can be mounted is arbitrary. is there. For example, the power control unit 160 described above may be mounted on an electronic device such as a digital camera, a mobile phone, or a PC.

(5) Modification 5
In the present invention, a plurality of constant current power supplies are used. However, the efficiency of any constant current power supply is improved in almost all regions as shown in FIG. 13 due to temperature change, deterioration with time, and variations in performance of the constant current power supply. Can be considered. This is the case when the temperature conditions due to environmental temperature and self-heating differ between constant-current power supplies, and the efficiency of the power supply differs due to changes in the characteristics of the transformer and capacitor. In addition, when the constant current power supply is used for a long time with either one being biased, it may be considered that the efficiency is different. In that case, the overall efficiency is better when the efficient (high) constant current power supply is operated with priority. In the example of FIG. 12, the temperature detection unit 166 is used. However, when the efficiency is calculated and used, an operation in consideration of the efficiency due to the temperature can be performed without providing a temperature detection unit.

  For example, the control unit 165 can calculate the efficiency of each constant current power source and switch the constant current power source that outputs the second current based on the calculated efficiency. FIG. 14 is a diagram illustrating a configuration example of the power control unit 160 of the present modification. In the example of FIG. 14, the power supply control unit 160 includes a first detection unit 171, a second detection unit 172, a third detection unit 173, a fourth detection unit 174, and a fifth detection unit 175.

  The first detection unit 171 is provided on the output side of the constant voltage power supply 161. The first detector 171 detects the output voltage V_Out and the output current I_Out1 output from the constant voltage power supply 161. The second detection unit 172 is provided on the input side of the first constant current power supply 162. The second detection unit 172 detects the input voltage V_In and the input current I_In1 input to the first constant current power supply 162. In this example, the second detection unit 172 can be considered to correspond to the “input voltage detection unit” in the claims, but is not limited thereto. The third detection unit 173 is provided on the output side of the first constant current power supply 162. The third detection unit 173 detects the output current I_Out1 output from the first constant current power supply 162. The fourth detection unit 174 is provided on the input side of the second constant current power source 163. The fourth detection unit 174 detects the input current I_In2 input to the second constant current power source 163. The fifth detection unit 175 is provided on the output side of the second constant current power source 163. The fifth detection unit 175 detects the output current I_Out2 output from the second constant current power source 163.

  Note that the output voltage V_Out may be set to the set value of the constant voltage power supply 161 and the function of detecting the output voltage V_Out may not be provided. If the voltage value fluctuates, the accuracy of the measurement decreases, but if not, there is no problem. The input voltage V_In may be converted to a fixed value without providing a function for detecting the input voltage V_In because it is often known without measurement if there is no large variation.

  The efficiency of the power supply is obtained by (output voltage V_Out × output current I_Out) / (input voltage V_In × input current I_In). The controller 165 uses the output voltage V_Out detected by the first detector 171, the input voltage V_In and input current I_In 1 detected by the second detector 172, and the output current I_Out 1 detected by the third detector 173. The efficiency of the first constant current power supply 162 can be calculated. The control unit 165 also includes an output voltage V_Out detected by the first detection unit 171, an input voltage V_In detected by the second detection unit 172, an input current I_In 2 detected by the fourth detection unit 174, and a fifth detection unit. Using the output current I_Out2 detected by 175, the efficiency of the second constant current power supply 163 can be calculated.

  The control unit 165 in the present modification activates only the constant voltage power supply 161 and turns off each of the first switch SW1 and the second switch SW2 when the current (total current) to be merged at the merge point Z is 6 A or less. Control. When the total current exceeds 6A and is 11A or less, the control unit 165 activates the more efficient (higher) one of the first constant current power supply 162 and the second constant current power supply 163, A 5 A current is output from the activated constant current power source. When the total current is 6A to 11A, the current (second current) output from the first constant current power supply 162 or the second constant current power supply 163 is fixed to 5A, while being output from the constant voltage power supply 161. The current (first current) changes from 1A to 6A and absorbs the fluctuation.

  Further, when the total current exceeds 11 A, the control unit 165 activates the remaining constant current power supply (the one having the lower efficiency of the first constant current power supply 162 and the second constant current power supply 163). When the total current exceeds 11 A, the second current output from each of the first constant current power supply 162 and the second constant current power supply 163 is fixed to 5 A, while the first current output from the constant voltage power supply 161 is used. The current changes from 1A to 6A and absorbs the fluctuation.

  FIG. 15 shows an example of the relationship between the total current and the breakdown of the current output from each power source (constant voltage power source 161, first constant current power source 162, second constant current power source 163) in this modification. It is a figure shown typically. A region P1 illustrated in FIG. 15 indicates a region where the first current from the constant voltage power supply 161 is output, and a region P22 illustrated in FIG. 15 includes the first constant current power supply 162 and the second constant current power supply 163. The region where the second current (fixed at 5A) from the higher efficiency is output is shown, and the region P33 shown in FIG. 15 has the lower efficiency of the first constant current power source 162 and the second constant current power source 163. The area | region where the 2nd electric current (fixed at 5A) from the direction is output is shown.

  The reason why the switching conditions are 6A and 11A is the same as in the first embodiment. In addition, it is possible to perform control for giving hysteresis to the switching as in the above-described second embodiment, or to perform control for variably setting the value of the second current as in the above-described fourth embodiment. You can also.

  The control unit 165 can write the calculated efficiency in a storage unit (not shown) such as an SRAM or a flash memory. FIG. 16 is a diagram illustrating an example of the efficiency table held in the storage unit. Each time the control unit 165 calculates the efficiency of each of the first constant current power source 162 and the second constant current power source 163, the control unit 165 updates the efficiency table and refers to this to determine the higher constant current power source. Start with priority. In this example, since the constant current power supply is used at a fixed current value, the efficiency table is a table with one row and two columns. The place where the storage unit is provided is arbitrary. For example, the storage unit may be provided inside the control unit 165, or the storage unit may be provided outside the control unit 165.

  FIG. 17 is a diagram illustrating an operation flow of the control unit 165. As illustrated in FIG. 17, the control unit 165 receives the input voltage V_In, the input from the first detection unit 171, the second detection unit 172, the third detection unit 173, the fourth detection unit 174, and the fifth detection unit 175. The current (I_In1-2), the output voltage V_Out, and the output current (I_Out1-3) are acquired (step S10). Next, the control unit 165 calculates the efficiency of the first constant current power supply 162 and the second constant current power supply 163 using the value acquired in step S1, and the value of the efficiency table held in the storage unit Is updated (step S11).

  And the control part 165 judges whether a total electric current is 6 A or less (step S12). When it is determined that the total current is 6 A or less (step S12: YES), the control unit 165 activates only the constant voltage power supply 161 (step S13). On the other hand, when the total current exceeds 6A (step S12: NO), the control unit 165 determines whether or not the total current is 11A or less (step S14). When it is determined that the total current is 11 A or less (step S14: YES), the control unit 165 refers to the efficiency table, and the efficiency of the first constant current power supply 162 is greater than the efficiency of the second constant current power supply 163. It is determined whether or not the value is too high (step S15).

  In step S15 described above, when it is determined that the efficiency of the first constant current power supply 162 is higher than the efficiency of the second constant current power supply 163 (step S15: YES), the control unit 165 activates the constant voltage power supply 161. The first switch SW1 is turned on and the second switch SW2 is turned off (step S16). That is, the first constant current power supply 162 is activated and the second constant current power supply 163 is not activated. On the other hand, in step S15 described above, when it is determined that the efficiency of the first constant current power supply 162 is lower than the efficiency of the second constant current power supply 163 (step S15: NO), the control unit 165 controls the constant voltage power supply 161. Is activated, the first switch SW1 is turned off, and the second switch SW2 is turned on (step S17). That is, the second constant current power source 163 is activated and the first constant current power source 162 is not activated. That is, the control unit 165 preferentially selects a constant current power source with high efficiency as the constant current power source that outputs the second current.

  Further, when it is determined in step S14 described above that the total current exceeds 11 A (step S14: NO), the control unit 165 activates the constant voltage power supply 161 to turn on the first switch SW1 and the second switch SW2. Each is turned on (step S18). That is, both the first constant current power supply 162 and the second constant current power supply 163 are activated. The above is the content of the operation flow of the control unit 165, and the control unit 165 repeats the above operation flow.

  As described with reference to FIG. 13, the efficiency may change depending on conditions. Therefore, it is conceivable that the most efficient point changes when the efficiency changes. FIG. 18 is a diagram exemplifying a case where the peak of efficiency at 5A originally changed to show the peak of efficiency at 5.5A depending on use conditions. Since it is desirable to use the constant current power supply with the most efficient current, in the case of FIG. 18, the overall efficiency is improved by changing the current of the constant current power supply from 5 A to 5.5 A.

  For example, the above storage unit may store an efficiency table in which the efficiency of the constant current power supply is associated with each value of the second current that can be output. The control unit 165 can also operate the constant current power supply with the second current value indicating the highest efficiency by referring to the efficiency table stored in the storage unit. In this example, the efficiency table can be regarded as corresponding to “correspondence information” in the claims. FIG. 19 is a diagram illustrating an example of the efficiency table. In this example, the control unit 165 has a function of updating the efficiency of 4A to 5.5A as needed. In the example of FIG. 19, in the initial table, the efficiency of 92% at 5A is the most efficient, but the efficiency after the change of conditions is the most efficient at efficiency of 90% at 5.5A. Therefore, the control unit 165 sets the most efficient 5.5A in this table as the operating current of the constant current power source. In the example of FIG. 19, the range of the efficiency table is set to 4A to 5.5A because the most efficient point may change from the higher side to the lower side. When a constant current power source is used up to a very low current range, the efficiency is worse than that of a constant voltage power source. Therefore, in this example, 4A is set as the lower limit, but the present invention is not limited to this. The efficiency can also be held in the efficiency table.

  Now, for example, a case is assumed where the efficiency is highest when the value of the operating current (second current) of the first constant current power supply 162 is 5.5A. FIG. 20 schematically shows an example of the relationship between the total current and the breakdown of the current output from each power source (constant voltage power source 161, first constant current power source 162, second constant current power source 163) in this case. FIG. In the example of FIG. 20, when the total current is 6A, the control unit 165 starts up the first constant current power supply 162 (controls the first switch SW1 to be on), and when the total current exceeds 6.5A, The second current output from the first constant current power supply 162 is controlled to 5.5A. In the example of FIG. 20, when the total current is 11 A, the second constant current power supply 163 is activated (the second switch SW2 is controlled to be turned on). For example, the control unit 165 outputs 1 A of the first current output from the constant voltage power supply 161, 5.5 A of the second current output from the first constant current power supply 162, and is output from the second constant current power supply 163. The second current is controlled to 4.5A.

  Here, the case where only the first constant current power supply 162 is used while being changed from the initial setting of 5 A has been described as an example. However, for example, the operating current (second current) of the second constant current power supply 163 is described. The case where the efficiency is the highest when the value of is different from the initial setting of 5A can be considered in the same manner as described above. Although detailed illustration is omitted, here, for each of the first constant current power supply 162 and the second constant current power supply 163, a corresponding efficiency table (see FIG. 19) is provided.

  In addition, for example, in an image forming apparatus, a configuration in which two power cords of an AC power supply (AC) are used when a large electric power such as a motor or a fixing device is used is known. Typically, such a configuration is adopted when a current exceeding the current rating of the power cord or the supply line is used. For example, as shown in FIG. 21, only the second constant current power source 163 may be connected to the second power cord.

  The above embodiments and modifications can be arbitrarily combined.

  In addition, the control part 165 of each above-mentioned embodiment may be comprised with the normal computer apparatus provided with CPU, ROM, RAM, etc. And the function of the above-mentioned control part 165 is realized because CPU develops and runs the program stored in ROM etc. on RAM. The program executed by the CPU of the control unit 165 is an installable or executable file and can be read by a computer such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD (Digital Versatile Disk). You may comprise so that it may record and provide on a recording medium.

  Further, the program executed by the CPU of the control unit 165 may be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. Further, the program executed by the CPU of the control unit 165 may be provided or distributed via a network such as the Internet.

DESCRIPTION OF SYMBOLS 100 Image forming system 102 Large capacity paper supply unit 103 Inserter 104 Folding unit 105 Finisher 106 Cutting machine 110 Image forming apparatus 120 I / F part 130 Printing part 140 Other I / F part 150 Operation display part 160 Power supply control part 161 Constant voltage power supply 162 First constant current power source 163 Second constant current power source 164 Current detection unit 165 Control unit 166 Temperature detection unit 200 External controller 210 Communication I / F unit 220 Image processing unit 240 Storage unit 250 I / F unit 300 AC power source 400 load

JP 2010-204427 A

Claims (14)

A power supply device for controlling a current supplied to a load,
A constant voltage power source for outputting a first current of a constant voltage;
One or more constant current power supplies for outputting a constant second current;
A current detection unit for detecting at least a first current output from the constant voltage power supply;
A control unit that controls supply and stop of the second current to the load according to the current detected by the current detection unit,
A power supply device characterized by that. When the current detected by the current detection unit is greater than or equal to a first threshold, the control unit performs control to start supplying the second current to the load, while the current detected by the current detection unit If it is equal to or lower than a second threshold value different from the first threshold value, a control for stopping the supply of the second current to the load is performed.
The power supply device according to claim 1. The first threshold is greater than the second threshold;
The power supply device according to claim 2. The second current is set to a value at which the efficiency of the constant current power supply exceeds the efficiency of the constant voltage power supply,
The power supply device according to claim 1. According to the control by the control unit, further comprising a switching unit for switching the availability of current input to the constant current power supply,
The control unit controls supply and stop of the second current to the load by switching the switching unit.
The power supply device according to claim 1. The control unit determines whether or not the second current can be supplied to the load for each operation state of an electronic device including the power supply device.
The power supply device according to claim 1. The value of the second current can be variably set.
The power supply device according to claim 1. A temperature detection unit for detecting the temperature;
The control unit controls the supply and stop of the second current to the load according to the current detected by the current detection unit and the temperature detected by the temperature detection unit.
The power supply device according to claim 1. The power supply device has a plurality of the constant current power supplies,
The control unit calculates the efficiency of each constant current power source, and switches the constant current power source that outputs the second current based on the calculated efficiency.
The power supply device according to claim 1. The control unit preferentially selects the high-efficiency constant-current power supply as the constant-current power supply that outputs the second current.
The power supply device according to claim 9. An input voltage detector for detecting a voltage on an input side of each of the constant current power supplies;
The power supply device according to claim 9. Storage means for storing correspondence information in which the efficiency of the constant current power source is associated with each value of the second current that can be output;
The control unit refers to the correspondence information, and operates the constant current power source at a value of the second current indicating the highest efficiency.
The power supply device according to claim 9.   The electronic device provided with the power supply device in any one of Claims 1 thru | or 12. A system comprising at least electronic equipment,
The electronic device is
A constant voltage power source for outputting a first current of a constant voltage;
One or more constant current power supplies for outputting a constant second current;
A current detection unit for detecting at least a first current output from the constant voltage power source,
The system
A control unit that controls supply and stop of the second current to a load according to the current detected by the current detection unit;
A system characterized by that.

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