JP5141385B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to a technique for reducing power consumption of an image forming apparatus.

In recent years, development of energy-saving technology has been increasingly demanded as environmental problems become more serious. Also in image forming apparatuses, power-saving techniques using secondary batteries are actively studied.
For example, focusing on the fact that a large amount of power is consumed when the fixing device is warmed up and the toner image is melted and fixed on a recording sheet, a technique for saving power by supplying power from a secondary battery is disclosed. (See Patent Documents 1 and 2).

Further, the period in which the image forming apparatus is in the standby state or in the power saving mode has a small power consumption per unit time, but is significantly longer than the period in which activation or image formation is performed, and the power consumption is not small. Focusing on this, a technique for saving power by supplying power from a secondary battery during standby or in a power saving mode is also disclosed (see Patent Document 3).
JP 2002-14574 A JP 2004-294554 A JP-A-7-199739

However, environmental problems such as global warming are steadily getting worse, and there is an urgent need not only to use secondary batteries but also to save more power.
SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that saves power by efficiently charging and discharging a secondary battery.

To achieve the above object, an image forming apparatus according to the present invention receiving the AC power into a DC power, a converter for supplying power to the load circuit branches a DC power portion of from the transducer When the storage means for supplying the stored DC power to the load circuit and the amount of current consumed by the load circuit are lower than a current amount range in which the conversion efficiency of the converter is not less than a predetermined value, , a current amount of the converter output to the load circuit, such that the sum of the amount of current the converter output to the accumulator unit is within the above range, by adjusting the amount of current to be output to the accumulator unit When the amount of current consumed by the load circuit exceeds the range, adjustment for adjusting the amount of power supplied from the power storage means to the load circuit so that the amount of current output by the converter is within the range. be characterized by obtaining Bei means, the .

Thus, as the sum of the amount of current load circuit stores electric current amount and the power storage means for consumption, the amount of current conversion efficiency of the transducer is within the range, the load from the storage means Since the amount of power supplied to the circuit is adjusted , the conversion efficiency of the converter can be increased to save power .

Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.
[1] Configuration of Image Forming Apparatus First, the configuration of an image forming apparatus according to an embodiment of the present invention will be described.
FIG. 1 is an external view of the image forming apparatus according to the present embodiment. As shown in FIG. 1, the image forming apparatus 1 includes an image reading unit 101, an image forming unit 102, a paper feeder 103, a finisher 104, and a multi-tray 105.

The image reading unit 101 automatically conveys and reads a document by an automatic document feeder, and generates image data.
The image forming unit 102 forms an image on recording paper supplied by the paper feeder 103 based on the image data generated by the image reading unit 101. The recording paper on which the image forming unit 102 has formed an image is discharged to the finisher 104 or the multi-tray 105.

Although not shown, the image forming unit 102 has a built-in power supply and supplies power to the image reading unit 101, the paper feeder 103, the finisher 104, and the multi-tray 105.
[2] Functional Configuration of Image Forming Apparatus Next, main functional configurations of the image forming apparatus 1 will be described.

FIG. 2 is a block diagram illustrating a main functional configuration of the image forming apparatus 1. As illustrated in FIG. 2, the image forming apparatus 1 includes a stabilized power source 200, a power storage unit 210, a low voltage load 211, and a high voltage load 212.
The image forming apparatus 1 receives AC power from the commercial power source 220 via the power cable 215, the inlet 214, and the main switch 213 by the stabilized power source 200.

The stabilized power supply 200 includes an AD converter 201, a current detector 202, and a drive circuit 203. The AD converter 201 is a so-called switching regulator, converts received AC power into DC power, and supplies the DC power to the low-voltage load 211 via the current detection unit 202.
The low-voltage load 211 includes a circuit and a drive source that operate at a low voltage, such as a control controller unit that controls the operation of the image forming apparatus 1 and a printer engine unit that executes an image process. For example, the controller unit is driven at 3.3V, and the printer engine unit is driven at 5V or 24V.

The power storage unit 210 is charged by receiving DC power supplied from the AD converter 201 according to the amount of current detected by the current detection unit 202, or the power storage unit 210 discharges DC power to the low voltage load 220. .
The drive circuit 204 supplies AC power to the high voltage load 212. The high-voltage load 212 is, for example, a fixing device, which heats and melts toner using a halogen heater and presses the toner onto a recording sheet. The high voltage load 212 is driven at 100 V, for example.

[3] Configuration of Current Detection Unit 202 and Power Storage Unit 210 Next, the configuration of the current detection unit 202 and the power storage unit 210 will be described.
FIG. 3 is a diagram illustrating a configuration of the current detection unit 202 and the power storage unit 210.
As shown in FIG. 3, the current detection unit 202 includes a resistance element 310, comparators 311 to 313, and reference voltage sources Vref1 and Vref2. When the AD converter 201 supplies DC power to the low-voltage load 211, a current flows through the resistance element 310, and a potential difference corresponding to the amount of current is generated between both ends of the resistance element 310.

The comparator 311 detects the potential difference and inputs it to the inverting input terminal of the comparator 312 and the non-inverting input terminal of the comparator 313. The comparator 312 outputs a voltage obtained by subtracting the potential difference from the reference voltage Vref1 to the power storage unit 210. Similarly, the comparator 313 outputs a voltage obtained by subtracting the reference voltage Vref2 from the potential difference to the power storage unit 210.
The power storage unit 210 includes relays 301 and 305, a charging current adjustment unit 302, a storage battery 303, a discharge current adjustment unit 304, and transistors 306 and 307.

  The transistor 306 turns on and off the relay 301 in accordance with the output voltage of the comparator 312. Further, the charging current adjustment unit 302 adjusts the amount of current input to the storage battery 303 according to the output voltage of the comparator 312. As a result, when the amount of current supplied from the AD converter 201 to the low-voltage load 211 is small, the current corresponding to the amount of current is input to the storage battery 303, so the output of the AD converter 201 is adjusted within a predetermined range. Is done.

  The transistor 307 turns on / off the relay 305 in accordance with the output voltage of the comparator 313. Further, the discharge current adjustment unit 304 adjusts the amount of current output from the storage battery 303 according to the output voltage of the comparator 313. As a result, when the amount of current supplied from the AD converter 201 to the low voltage load 211 is large, power is also supplied from the storage battery 303 to the low voltage load 211, so that the output of the AD converter 201 is adjusted within a predetermined range.

[4] Operation of Power Storage Unit 210 Next, the operation of the power storage unit 210 will be described.
FIG. 4 is a graph showing the relationship between the amount of current output from the AD converter 201 and the AD conversion efficiency. As shown in FIG. 4, the conversion efficiency of the AD converter 201 improves as the output current amount increases from 0 A, and decreases when the optimum efficiency is exceeded.

In this embodiment, when the amount of current output from the AD converter 201 is about 6 A, the AD conversion efficiency is the highest, which is about 85%. Further, when the output current amount is in the range of 4.4 A (Ilow) or more and 9.2 A (Ihigh) or less, the AD conversion efficiency is 80% or more.
FIG. 5 is a graph showing the relationship between the amount of current consumed by the low-voltage load 211, the amount of output current of the AD converter 201, and the amount of current charged / discharged by the power storage unit 210. As shown in FIG. 5, when the amount of current consumed by the low-voltage load 211 is less than Ilow, the storage current is input to the storage unit 210 so that the output current amount of the AD converter 201 is equal to Ilow. .

Further, when the current consumption amount of the low voltage load 211 is in the range from Ilow to Ihigh, the power storage unit 210 is not charged and discharged, and the low voltage load 211 is fed only from the AD converter 201.
Further, when the current consumption amount of the low voltage load 211 exceeds Ihigh, the power storage unit 210 also supplies power to the low voltage load 211 so that the output power amount of the AD converter 201 becomes equal to Ihigh.

Even if the low-voltage load 211 consumes a current of 6 A or more when performing image formation such as copying or printing, and consumes a current of about 2 A during standby and about 1 A in the energy saving mode, for example, In this case, since the conversion efficiency of the AD converter 201 can always be maintained at 80% or more, the power consumption of the image forming apparatus 1 can be saved.
[5] Modifications Although the present invention has been described based on the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and the following modifications can be implemented. .

(1) In the above embodiment, the case where the conversion efficiency of the AD converter 201 is maintained at 80% or more has been described, but the present invention is not limited to this, and a value other than 80% is used as a reference. May be.
(2) Although not particularly mentioned in the above embodiment, the number of storage batteries provided in the power storage unit 201 is not limited to one, and a plurality of storage batteries may be connected in parallel, or the storage batteries to be used are switched. Also good.

A nickel cadmium battery, a nickel hydride battery, a lithium ion battery, or an electric double layer capacitor may be used as the storage battery.
Nickel metal hydride batteries have a rated capacity of several hundred mAh to 10,000 mAh, and generally have a charging current of 1 coulomb or less that can be safely charged without significantly reducing the service life. This 1 coulomb or less means that, for example, if the rated capacity is 1000 mAh, the charging current is 1 A or less.

  (3) Although not particularly mentioned in the above embodiment, the control controller unit of the low-voltage load 211 is a CPU (Central Processing Unit), a memory, a hard disk, an authentication device, a FAX controller, a standard printer controller, and an optional printer. A controller, an image processing controller, a scanner controller, an operation panel controller, and the like may be included.

The printer engine unit includes a mechanical controller circuit, driving parts (motors, solenoids, electromagnetic clutches, etc.), various sensors, image process parts, optional devices (automatic document reading device, billing device, discharged paper sorting device, etc.), etc. May be.
(4) In the above embodiment, the case where the amount of current charged / discharged by the power storage unit is changed in proportion to the amount of current consumed by the low-voltage load 211 has been described, but it goes without saying that the present invention is not limited to this. As long as the conversion efficiency of the AD converter 201 is equal to or higher than a desired value, the charge / discharge amount of the power storage unit may take another value.

For example, the power storage unit may be charged and discharged with a constant current amount in both charging and discharging. That is, when the amount of current consumed by the low-voltage load 211 is less than Ilow, the charging current Icharge of the power storage unit is expressed by the formula Ilow ≦ Icharge + Iconsume ≦ Ihigh.
Should be satisfied. When the current consumption amount of the low-voltage load 211 exceeds Ihigh, the discharge current Idischarge of the power storage unit is expressed by the formula Ilow ≦ Icharge−Iconsume ≦ Ihigh.
Should be satisfied. In this way, the effects of the present invention can be obtained even when the charge / discharge current of the power storage unit is a fixed amount.

  The present invention according to the present invention is useful as a technique for reducing power consumption of an image forming apparatus.

1 is an external view of an image forming apparatus according to an embodiment of the present invention. 2 is a block diagram illustrating a main functional configuration of the image forming apparatus 1. FIG. FIG. 3 is a diagram showing the configuration of a current detection unit 202 and a power storage unit 210. It is a graph which shows the relationship between the electric current amount which AD converter 201 outputs, and the efficiency of AD conversion. 5 is a graph showing the relationship between the amount of current consumed by the low-voltage load 211, the amount of output current of the AD converter 201, and the amount of current charged / discharged by the power storage unit 210.

Explanation of symbols

1 ……………… Image forming apparatus 200 ……………… Stabilized power supply 201 ……………… AD converter 202 ……………… Current detector 203 ……………… Drive Circuit 210..., Storage unit 211... Low voltage load 212. Adjustment unit 303... Storage battery 304... Discharge current adjustment unit 310... Resistance elements 311 to 313.

Claims (1)

A converter that receives AC power, converts it to DC power, and feeds the load circuit;
While power storage branches a part of the DC power from the converter, a power storage unit for supplying a power storage and DC power to the load circuit,
The amount of current the load circuit is consumed, if the conversion efficiency of the transducer is lower than the range of the amount of current equal to or greater than a predetermined value, the current amount of the converter output to the load circuit, said converter wherein as the sum of the current amount to be output to the accumulator unit is within the above range, by adjusting the amount of current to be output to the accumulator unit,
When the amount of current consumed by the load circuit exceeds the range, the adjusting unit adjusts the amount of power supplied from the power storage unit to the load circuit so that the amount of current output from the converter is within the range. When the image forming apparatus according to claim Bei obtain <br/> things.

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