JP2015138112A - Power supply device and image forming device with power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow an external input power to be leveled to an upper limit of a preset external input power or lower.SOLUTION: A power supply device comprising a first power supply (AC/DC converter) 12 which uses an external power as an input source and a second power supply 14 which uses an output of a storage battery 143 as the input source supplies power to constant voltage load power supply units (18, 20) supplying power to constant voltage loads (18a, 20a) via a DC internal bus 15 and a heater power supply unit 22 supplying power to a fixing heater 22a. The power supply device further comprises a load power detection unit 16 which detects the load power of the DC internal bus 15, and a power supply control unit 30 which controls the outputs of the first power supply 12 and the second power supply 14. When the load power detected by the load power detection unit 16 exceeds a first threshold value, the power supply control unit 30 supplies the exceeding power from the second power supply 14 to the DC internal bus 15.

Description

  The present invention relates to a power supply device and an image forming apparatus including the power supply device.

  2. Description of the Related Art There is known a power supply device that supplies power to equipment by switching between a main power supply and an auxiliary power supply. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-209149) discloses a first power source with a constant voltage output that uses power supplied from the outside as an input source, a power storage device, and power of the power storage device as an input source. A power supply device that includes two power supplies and supplies both power from a first power supply and power from a second power supply to a load at the same time is described.

  In this power supply device, the output of the second power supply is controlled based on the output current value of the first power supply. In other words, the output current value of the first power supply is detected, and power is supplied from the second power supply so that it is below a certain upper limit current. Thereby, a part of the electric power used in the constant voltage load is supplied from the power storage device. The fixing power source of this power supply device uses AC power supplied from the outside as an input source and supplies AC power to the fixing heater by a fixing power instruction signal to cause the fixing heater to generate heat.

Incidentally, it is generally known that the maximum value of the power for heating the fixing heater is larger than the power used by the constant voltage load. For example, the power used in the constant voltage load is about 600 W, but the maximum value of the power for heating the fixing heater is set to 900 W.
On the other hand, in this power supply apparatus, the fixing power supply uses AC power supplied from the outside as an input source. Therefore, in this power supply device, the external power cannot be leveled for the fixing power source that consumes a larger amount of power than the constant voltage load.

  In addition, in this power supply device, the power of the constant voltage load can be covered only by the power from the storage battery, but the fixing power supply uses the AC power supplied from the outside as the input source, so all power is supplied by the power from the storage battery. It is not possible. Therefore, the power failure backup function corresponding to the time of power failure of the external power source cannot be sufficiently achieved.

  The present invention has been made in view of the above problems in the conventional power supply apparatus, and an object thereof is to level the power of the external input to be equal to or lower than the first threshold value.

  According to the present invention, a first power source having a constant voltage output using an externally supplied power as an input source and an output of a second power source using an output of a storage battery as an input source are connected in parallel, and the power from the first power source And a power supply device for simultaneously supplying power from the second power source to a load, a constant voltage load power supply unit for supplying power to a constant voltage load, a heater power supply unit for supplying power to a heater, A DC internal bus that connects one power source, the second power source, the constant voltage load power supply unit, and the heater power supply unit; a load power detection unit that detects load power of the DC internal bus; and the second power source A power control unit that controls the output of the second power source when the load power detected by the load power detection unit exceeds a first threshold value. To the DC internal bus A power supply unit.

  According to the present invention, the power of the external input can be leveled below the first threshold in the power supply device.

1 is a block diagram of a power supply device of an image forming apparatus according to a first embodiment of the present invention. 2A is a time change of load power in the image forming apparatus, FIG. 2B is a time change of power supplied from the storage battery, and FIG. 2C is an external view when the storage battery discharge power shown in FIG. 2B is supplied to the DC internal bus. It is a figure which shows the time change of input electric power, respectively. It is a block diagram of a power source for DC input fixing. FIG. 6 is a diagram showing a change over time of a fixing DC voltage output, which is an output of a DC input fixing power source, with the fixing power supply output on the vertical axis and time on the horizontal axis. 6 is a block diagram of a power supply device of an image forming apparatus according to a second embodiment. FIG. FIG. 10 is a block diagram of a power supply device of an image forming apparatus according to a third embodiment. FIG. 10 is a block diagram of a power supply device of an image forming apparatus according to a fourth embodiment. It is a figure explaining operation | movement of the power supply device of 4th Embodiment.

The present invention is provided with a power storage device in addition to a power source that regularly uses power supplied from the outside, and when a large amount of power is required for the operation of a device that uses the power source, the power stored in the power storage device is used as a load. The present invention relates to a power supply apparatus for leveling commercial AC power consumption so that the external input power of the device does not exceed the power that can be supplied by the power supply.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram of a power supply device of an image forming apparatus according to the first embodiment of the present invention.
The power supply device includes a first power source 12 connected to an external AC power source PS through a filter 10, a second power source 14 including a charging circuit 141, a discharging circuit 142, and a storage battery 143, a constant voltage load (24V system load 18a, The 5V system load 20a) and the fixing heater 22a correspond to the constant voltage load and the fixing heater 22a, and a constant voltage load power supply unit (DC / DC converter (24V output) 18, DC / DC converter (5V output)). 20) and a DC input fixing power source 22.

  The power supply apparatus also includes a load power detection unit 16 that detects the load power of the DC internal bus 15, a load power detection unit 16, a load power value detected by the load power detection unit 16, and the second power supply 14. A power supply control unit 30 is provided for instructing fixing power to the DC input fixing power source 22 based on a charging / discharging power instruction and a fixing control signal from the engine control unit 40.

  The first power supply (AC / DC converter) 12 outputs a constant voltage using externally supplied power (commercial AC power supply power) as an input source. That is, commercial AC power input (electric power) is input to the AC / DC converter 12 through the filter 10. The AC / DC converter 12 outputs a DC voltage (for example, 220 V) based on the commercial AC power input. The DC internal bus 15 (220V) from which the DC voltage is output includes a constant voltage load power supply unit (DC / DC converter (24V output) 18 for supplying power to a constant voltage load of the image forming apparatus, a DC / DC converter ( 5V output) 20) and a DC input fixing power source 22 for supplying power to the fixing heater 22a. A 24V system load 18a, a 5V system load 20a, and a fixing heater 22a are connected to each power output.

  The engine control unit 40 of the image forming apparatus is necessary for controlling a CPU (Central Processing Unit) (not shown), an IPP (Image Processing Processor) that performs image processing, copying, and printout, as in the related art. A ROM (Read Only Memory) having a program built therein, a RAM (Random Access Memory) necessary for the control, and an NV (Non-Volatile) -RAM are provided, and image formation control, that is, image formation control is mainly performed. It also has a serial interface for transmitting and receiving signals to and from other CPUs for controlling, and controls I / O (input / output of counters, fans, solenoids, motors, etc.) connected to the engine control board.

From the engine control unit 40, a fixing control signal for controlling the fixing temperature is input to the power supply control unit 30. The power supply control unit 30 outputs a fixing power instruction to the DC input fixing power supply 22 based on the fixing control signal. The DC input fixing power source 22 supplies power to the fixing heater 22a in accordance with a fixing power instruction with the configuration shown in FIG. 3 to be described later.
The power (load power) consumed by the 24V system load 18a, the 5V system load 20a and the fixing heater 22a is detected by the load power detection unit 16. Since the DC voltage output is a constant voltage, the current detection is substituted for the current detection, and the power is calculated using the voltage value of the DC voltage (constant voltage) output known in advance.

Next, the operation of the power supply device of this embodiment will be described with reference to FIG.
Here, a method of leveling the external input power by the output from the storage battery 143 will be described. FIG. 2A shows a change in load power with time in the image forming apparatus.
The load power that is the sum of the power of the 24V system load 18a, the 5V system load 20a, and the fixing heater 22a is small when the image forming apparatus is on standby. However, when printing is started, a large load power is required because the fixing roller 22a heats a fixing roller (not shown) until it reaches a necessary temperature.

  When printing on a plurality of sheets, the power supply control unit 30 controls the heating of the fixing heater 22a in order to maintain the temperature of the fixing roller at a necessary temperature, and returns to the standby power when printing is completed. When all of this load power is supplied by external input power, a large maximum power is required. However, the image forming apparatus rarely continues printing at all times, and in fact, it takes a long time to wait for a print command with power during standby. Therefore, in the present embodiment, an upper limit value (first threshold value) of the external input power is set, and power exceeding the upper limit value is supplied from the storage battery 143 to the DC internal bus 15. In other words, in this case, the power from the first power source 12 and the power from the second power source 14 are simultaneously supplied to the load (constant voltage loads (18a, 20a) and the fixing heater 22a), so that the external input power is externally input. Leveling below the upper limit of power.

FIG. 2B is a diagram illustrating a change over time in the power supplied from the storage battery 143.
In the present embodiment, the power supply control unit 30 instructs the discharge circuit 142 of the storage battery 143 to discharge power, and supplies the power of the storage battery 143 to the DC internal bus 15.
In this case, the storage battery 143 connected to the DC internal bus, the load power, and the external input power have the following relationship.
External input power = load power-storage battery discharge power (1)
However, Expression (1) is established by instructing the storage battery discharge power so that the storage battery discharge power does not exceed the load power. Therefore, the discharge power of the storage battery
Battery discharge power = load power-upper limit value of external input power (2)
To be.

FIG. 2C is a diagram showing a time change of the external input power when the storage battery discharge power shown in FIG. 2B is supplied to the DC internal bus 15.
The relationship between the load power, the storage battery discharge power, and the external input power is expressed by Expression (1). By performing the discharge power instruction of Expression (2), the external input power becomes equal to or less than the upper limit value of the external input power as shown in FIG. 2C.

FIG. 3 is a block diagram of the DC input fixing power source 22.
The DC input fixing power source 22 corresponds to the heater power supply unit of the present invention, and includes a step-down DC / DC converter 221 and a fixing power command / output voltage command converter 222. The step-down DC / DC converter 221 uses an output voltage instruction input from the fixing power instruction / output voltage instruction conversion unit 222 based on an instruction from the power supply control unit 30 as a reference value, from an input DC voltage (for example, 220 V). The DC voltage specified by the output voltage instruction is output. The fixed DC voltage output of the step-down DC / DC converter 221 changes its DC voltage when the output voltage instruction changes.

  This fixing DC voltage output is supplied to the fixing heater 22a to heat the fixing heater 22a. The higher the fixing DC voltage output voltage is, the larger power is supplied to the fixing heater 22a. That is, the heating of the fixing heater 22a is controlled by controlling the voltage value of the fixing DC voltage output.

FIG. 4 is a diagram showing the change over time of the fixing DC voltage output, which is the output of the DC input fixing power source 22, with the fixing DC voltage output on the vertical axis and the time on the horizontal axis.
In the image forming apparatus, when printing is started from the standby state, a maximum voltage is applied to the fixing heater 22a to heat the fixing roller to a necessary temperature.
When the fixing heater 22a is a halogen heater, the resistance of the fixing heater 22a is small when the fixing heater 22a is cold. Therefore, in this case, as shown in FIG. 4, a method of avoiding the inrush current by changing the fixing DC voltage output in a ramp (gradient) shape to avoid the initial inrush current is used.

After the fixing roller reaches the required temperature, power is supplied to the fixing roller to maintain the temperature. FIG. 4 shows that the power supplied to the fixing heater 22 a is controlled by controlling the output voltage of the DC input fixing power source 22.
The fixing heater 22a is controlled by a fixing power instruction (signal) from the power supply control unit 30, and the inputted fixing power instruction is converted into an appropriate output voltage instruction by the fixing power instruction / output voltage instruction conversion unit 222. The The relationship between the power supplied to the step-down DC / DC converter 221 and the output voltage to the fixing heater 22a may be calculated at the time of this conversion, or the calculation result may be converted into table data in advance.

  Note that the step-down DC / DC converter 221 is generally known, and realizes voltage conversion with a simple configuration. Further, since power is supplied to the fixing heater 22a using the step-down DC / DC converter 221, the DC voltage input to the step-down DC / DC converter 221 is set higher than the maximum voltage applied to the fixing heater 22a. There is a need.

In the power supply apparatus shown in FIG. 1, the AC / DC converter 12 generates desired DC power by converting the AC voltage of the commercial AC power supply PS. The function of the AC / DC converter 12 is generally realized by an AC / DC converter (PFC circuit) that also has a PFC (Power Factor Correction) function in the case of an image forming apparatus that consumes a large amount of power. When the power consumption is small, it can be realized by a full-wave rectifier circuit.
When a PFC circuit is used, the DC internal bus voltage is set according to the input voltage and the boost ratio.

  The power supply control unit 30 determines whether or not the load power detected by the load power detection unit 16 exceeds a predetermined upper limit value of external input power from the input value of the load power detection unit 16. Here, when it exceeds, the calculation of Formula (2) is performed in the power supply control part 30, and a calculation result is output as a discharge power instruction | indication. The discharge power instruction is input to the discharge circuit 142 connected to the storage battery 143. The discharge circuit 142 discharges in accordance with the input discharge power instruction and supplies the power of the storage battery 143 to the DC internal bus 15.

Specifically, constant current output is performed with a current value corresponding to the discharge power (current = discharge power instruction / voltage value of DC internal bus 15). As a result, the external input power is reduced by the storage battery discharge power as shown in the equation (1), and therefore, is equal to or less than the upper limit of the external input power.
In order to prevent the external input power from exceeding a certain level, there may be a margin for the upper limit of the external input power. That is,
Upper limit of external input power = power that external input power must not exceed-marginal power (Equation 3)
This surplus power is effective when the discharge power from the storage battery 143 is supplied to the DC internal bus 15 with a delay when the load power changes.

In the power supply device of FIG. 1, the DC voltage of the DC internal bus 15 is 220 V here. As shown in FIG. 3, the DC input fixing power source 22 uses a step-down DC / DC converter 221, and the DC voltage of the DC internal bus 15 as an input voltage is higher than the maximum applied voltage of the fixing heater 22a. is necessary. For example, when the fixing heater 22a having a rating of 100V is used, the DC voltage of the DC internal bus 15 needs to be 100V or more.
On the other hand, the battery voltage is often 48V or 24V. Therefore, the difference from the fixed DC voltage output is large, the voltage conversion ratio of the DC / DC converter performed by the charging circuit 141 and the discharging circuit 142 is increased, and the circuit is increased and the conversion efficiency is deteriorated. Therefore, the DC voltage of the DC internal bus 15 is selected as the maximum voltage applied to the fixing heater 22a.

When the AC / DC converter 12 is a PFC circuit, a boost type PFC is generally used. Therefore, a voltage selected from the input AC power supply voltage and the boost ratio determined by the PFC format is used. You can also.
Regarding the charging of the storage battery 143, when the image forming apparatus is in a standby state and the value of the load power detection unit 16 is lower than a certain threshold value (second threshold value), charging is performed according to a charging power instruction from the power supply control unit 30. It is possible. It is also conceivable that the power supply control unit 30 has a clock function (not shown) and outputs a charging power instruction so that charging is performed at midnight when the electricity bill is low.

FIG. 5 is a block diagram of a power supply device of the image forming apparatus according to the second embodiment.
The embodiment of FIG. 5 is an AC / DC converter input power detection unit that detects the input power of the AC / DC converter 12 while omitting the load power detection unit 16 in the power supply device of the first embodiment shown in FIG. 24 is different from the first embodiment in that it is connected in parallel with the AC / DC converter 12 with respect to the filter 10, and the other points are the same. Therefore, the same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

In the present embodiment, the power supply control unit 30 sets the discharge circuit 142 so that the input power detected by the AC / DC converter input power detection unit 24 is equal to the set upper limit value (first threshold value) of the external input power. The discharge power instruction given to the is controlled.
Specifically, using the discharge power instruction from the power supply control unit 30 as a reference value, the input power of the AC / DC converter 12 detected by the AC / DC converter input power detection unit 24 and the upper limit value of the set external input power The difference is amplified and used as a discharge power instruction. Thereby, feedback control is performed. Although not shown in the present embodiment, the power supply control unit 30 performs calculations for the feedback processing.

FIG. 6 is a block diagram of a power supply device of the image forming apparatus according to the third embodiment.
In the embodiment of FIG. 6, power is supplied from the storage battery 143 only to the 5V standby load 21 a that needs to operate in a standby state in which the image forming apparatus is waiting for printing. A DC / DC converter (5V) which is an example of a second constant voltage load power supply unit having a maximum output voltage smaller than that of the load power supply unit (DC / DC converter (24V output) 18, DC / DC converter (5V output) 20). Output) 21 is connected. The third embodiment is different from the power supply device of the first embodiment in this point, and is the same as the first embodiment in other points. Therefore, the same parts as those of the power supply device of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The DC / DC converter (5V output) 21 converts the output voltages 48V, 24V, etc. of the storage battery 143 to 5V and supplies power to the 5V standby load 21a. As a result, the block of the AC / DC converter 12 (the block that receives power from the AC / DC converter 12) can be stopped during standby, and power to unnecessary blocks during standby is cut off, and external input power is reduced to 0W. Can be. For example, the standby power can be set to 0 in a standby state such as at night.

FIG. 7 is a block diagram of a power supply device of an image forming apparatus according to the fourth embodiment.
In the embodiment of FIG. 7, the power supply device of the first embodiment is an example of a voltage detection unit that detects the voltage of the DC internal bus 15 and outputs a signal when the voltage falls below a predetermined voltage (third threshold). It differs from the power supply device of the first embodiment in that a certain low voltage detection unit 26 and a constant voltage mode instruction unit 28 that changes the control mode of the discharge circuit according to the signal are added. Therefore, the same parts are denoted by the same reference numerals and description thereof is omitted.

FIG. 8 is a diagram for explaining the operation of the power supply device according to the fourth embodiment.
The voltage of the DC internal bus 15 is determined by the output voltage of the AC / DC converter 12. Usually, the rated output voltage (here, DC voltage 220V) set to the output voltage of the AC / DC converter 12 is output. Therefore, when a power failure occurs in the external AC power supply PS, the output voltage of the AC / DC converter 12 is lowered. The decrease in the output voltage is determined by the capacity of the output capacitor of the AC / DC converter 12 and the load power. However, the output voltage decreases greatly within a short time, and the DC / DC converter 18 that outputs 24V, the DC / DC converter 20 that outputs 5V, The DC input fixing power source 20 that drives the fixing heater 22a falls below the input voltage range in which it normally operates.

In the present embodiment, the low voltage detection unit 26 outputs a detection signal when it falls below a low voltage detection value (210 V in this case) that is a predetermined voltage (third threshold). This detection signal is input to a constant voltage mode instructing unit 28 that changes the control mode of the discharge circuit. The constant voltage mode instructing unit 28 sets the operation mode of the discharge circuit 142 as a constant current output when normal, and discharges and outputs to the DC internal bus 15 by constant current control in accordance with the designated discharge power instruction.
However, when the detection signal of the low voltage detection unit 26 is input, the constant voltage mode instruction unit 28 outputs a constant voltage mode instruction signal to the discharge circuit 142. Upon receiving this signal, the discharge circuit 142 shifts from the constant current control mode to the constant voltage control mode, and discharges and outputs so as to maintain a predetermined constant voltage (constant voltage mode output; here, 205 V). Thus, a constant voltage (205V) is supplied from the storage battery 143 to the DC internal bus 15 even during a power failure, and a backup operation during a power failure is possible.

  The low voltage detection value needs to be set larger than the constant voltage mode output voltage. The constant voltage mode output voltage includes a DC / DC converter 18 that outputs 24V connected to the DC internal bus 15, a DC / DC converter 20 that outputs 5V, and a DC input fixing power source 22 that drives the fixing heater 22a. It is necessary to set a value higher than the normal operating input voltage range.

  As described above, according to the present embodiment, by supplying power from the storage battery 143 to the 5V standby load 21a that needs to operate in the standby state, the standby power can be reduced to 0 in the standby state. In addition, a constant voltage is supplied from the storage battery 143 to the DC internal bus 15 even during a power failure, and a backup operation during a power failure is possible.

  DESCRIPTION OF SYMBOLS 10 ... Filter, 12 ... 1st power supply (AC / DC converter), 14 ... 2nd power supply, 141 ... Charging circuit, 142 ... Discharging circuit, 143 ... Storage battery, 15 * ··· DC internal bus, 16 ··· Load power detector, 18 ··· DC / DC converter (24V output), 18a · · · 24V system load, 20 · · · DC / DC converter (5V output), 20a ... 5V system load, 22 ... DC input fixing power supply, 22a ... Fixing heater, 221 ... Step-down DC / DC converter, 222 ... Fixing power instruction / output voltage instruction conversion unit, 24 ... AC / DC converter input power detection unit, 26 ... low voltage detection unit, 28 ... constant voltage mode instruction unit, 30 ... power supply control unit, 40 ... engine control unit.

JP 2007-209149 A

Claims (10)

A first power source having a constant voltage output using power supplied from the outside as an input source and an output of a second power source using the output of the storage battery as an input source are connected in parallel, and the power from the first power source and the second power source are connected. A power supply device that simultaneously supplies power from a power source to a load,
A constant voltage load power supply unit for supplying power to the constant voltage load;
A heater power supply for supplying power to the heater;
A DC internal bus connecting the first power source, the second power source, the constant voltage load power supply unit, and the heater power supply unit;
A load power detection unit for detecting the load power of the DC internal bus;
A power supply control unit for controlling the output of the second power supply,
The power source controller supplies the excess power from the second power source to the DC internal bus when the load power detected by the load power detector exceeds a first threshold. apparatus. The power supply device according to claim 1,
An input power detection unit for detecting input power input to the first power supply from outside;
The power supply control unit controls the output of the second power supply so that the input power detected by the input power detection unit is equal to the first threshold value. The power supply device according to claim 1,
A second constant voltage load power supply unit having a smaller maximum output voltage than the constant voltage load power supply unit;
The power supply control unit controls the power supply device to supply power from the second power supply to the second constant voltage load power supply unit when the power supply device is in a standby state. The power supply device according to any one of claims 1 to 3,
The power supply control unit controls the second power supply to be charged when the load power detected by the load power detection unit is lower than a second threshold value. The power supply device according to any one of claims 1 to 4,
A voltage detector for detecting the voltage of the DC internal bus;
When the voltage detected by the voltage detection unit is lower than a third threshold, the second power source is shifted from the constant current control mode to the constant voltage control mode, and the constant voltage output from the second power source causes the A power supply device for supplying power to a DC internal bus. The power supply device according to claim 5,
The power supply apparatus according to claim 1, wherein the third threshold value is set to be larger than a voltage for normally operating the constant voltage load power supply unit and the heater power supply unit. The power supply device according to any one of claims 1 to 6,
The heater power supply unit includes a step-down DC / DC converter. The power supply device according to claim 7,
The power supply apparatus according to claim 1, wherein the voltage of the DC internal bus is set higher than the maximum voltage applied to the heater. The power supply device according to claim 7,
The first power supply constitutes a PFC circuit,
The power supply apparatus according to claim 1, wherein the voltage of the DC internal bus is set by an input voltage of the PFC circuit and a boost ratio.   An image forming apparatus comprising the power supply device according to claim 1.

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