JP2021148996A - Power supply device and image forming apparatus - Google Patents

Abstract

To control a load current.SOLUTION: A power supply device according to the present invention comprises: a power supply unit that outputs a first current to supply power to a load; a storage unit that stores the capacitance of a leakage destination in which a second current that is part of the first current flows separately from the load; a voltage measuring unit that measures the voltage value of the first current; a frequency setting unit that sets the frequency of the first current; a calculation unit that calculates a second current value that is the current value of the second current based on the capacitance, the frequency, and the voltage value; a current measuring unit that measures a first current value of the first current; a specification unit that specifies the value of a load current flowing in the load based on the first current value and the second current value; and a control unit that controls to make the load current value constant.SELECTED DRAWING: Figure 2

Description

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

Conventionally, a technique for measuring a leakage current using an induced electromagnetic field is known.

Specifically, in order to measure the leakage current to the ground in a pair of electrical wirings, the leakage current measuring device first suppresses the magnetic field caused by the load current between the power supply side and the load side in the electrical wiring. Provide means. Then, the leakage current measuring device measures the leakage current to the ground based on the magnetic field generated in the vicinity of the magnetic field suppression conductive means. Next, the leakage current measuring device determines at least one of the ground leakage active current due to poor insulation and the ground leakage reactive current due to capacitance based on the line voltage and the measured ground leakage current. calculate. In this way, there is known a technique for measuring the leakage current of each branch line with high accuracy in the live line state (see, for example, Patent Document 1).

However, in the conventional technique, it may not be possible to control the current (hereinafter, referred to as “load current”) flowing through the load (hereinafter, simply referred to as “load”). That is, in the conventional technique, there is often no configuration for controlling the load current, which is limited to the measurement of the leaked current.

One aspect of the present invention is to control the load current.

The power supply unit according to one embodiment of the present invention
A power supply unit that outputs the first current to supply power to the load,
A storage unit that stores the capacitance of the leakage destination through which the second current, which is a part of the first current, flows separately from the load.
A voltage measuring unit that measures the voltage value of the first current,
A frequency setting unit that sets the frequency of the first current, and
A calculation unit that calculates a second current value, which is a current value of the second current, based on the capacitance, the frequency, and the voltage value.
A current measuring unit that measures the first current value of the first current, and
A specific unit that specifies the load current value flowing through the load based on the first current value and the second current value, and
It is provided with a control unit that controls the load current value to be constant.

According to the embodiment of the present invention, the load current can be controlled.

It is a figure which shows the example of the image forming apparatus. It is a figure which shows the circuit configuration example of a power supply device. It is a figure which shows the example of the equivalent circuit. It is a figure which shows the circuit structure example in the state which cut off the load. It is a figure which shows the example of the processing performed in a state where the load is cut off. It is a figure which shows the example of the processing performed with the load connected. It is a figure which shows the circuit structure of the 1st comparative example. It is a figure which shows the circuit structure of the 2nd comparative example. It is a figure which shows the functional configuration example of a power supply device.

Hereinafter, the optimum and minimum form for carrying out the invention will be described with reference to the drawings. In the drawings, when the same reference numerals are given, it is shown that the same configurations are used, and duplicate description will be omitted. Further, the specific example shown is an example, and a configuration other than that shown may be further included.

<Configuration example of power supply device and image forming device>
FIG. 1 is a diagram showing an example of an image forming apparatus. Hereinafter, an example will be described in which the image forming apparatus 1 includes the power supply apparatus 10.

For example, the image forming apparatus 1 includes a power supply device 10, a primary transfer power source 11, a photoconductor 2, a charging roller 3, an exposure device 4, a developing device 5, a primary transfer roller 6, an intermediate transfer belt 7, and a static eliminator 8. It is a hardware configuration having the above.

The power supply device 10 is a device that applies a load current 204 to the charging roller 3, which is an example of a load.

The charging roller 3 is an example of a charging portion that charges the photoconductor 2.

The exposure device 4 exposes the photoconductor 2 charged by the charging roller 3 based on an image signal. When the exposure is performed in this way, an electrostatic latent image is formed on the photoconductor 2.

The developer 5 attaches toner to the electrostatic latent image and forms the toner image on the photoconductor 2.

The primary transfer power supply 11 charges the primary transfer roller 6. When the primary transfer roller 6 is charged in this way, the toner image on the photoconductor 2 is transferred to the intermediate transfer belt 7.

After that, the toner image transferred to the intermediate transfer belt 7 is further transferred to the recording medium by the secondary transfer. Next, when fixing is performed, an image is formed on the recording medium.

The static eliminator 8 removes electric charges on the surface of the photoconductor 2. After the removal is completed, image formation is performed again.

Further, in color printing, that is, when a plurality of colors are used, a similar configuration is provided for each color.

For example, the image forming apparatus 1 forms an image on a recording medium based on the image data.

<Circuit configuration example of power supply device>
For example, the power supply device 10 has the following circuit configuration.

FIG. 2 is a diagram showing an example of a circuit configuration of a power supply device. For example, the power supply device 10 includes a CPU (Central Processing Unit, hereinafter referred to as “CPU 101”), a driver 102, a transformer 103, a first resistor 104, a second resistor 105, a first rectifying circuit 106, and a second rectifying circuit 107. , Memory 108, third resistor 109, and the like. The power supply device 10 is connected to the load 111 by wiring 110. Therefore, the power supply device 10 supplies electric power to the load 111 via the wiring 110.

Hereinafter, the current generated in the power supply device 10 (in this example, the current output from the transformer 103 and before the leakage of the current) is referred to as "first current 200". Further, the output current execution value of the first current 200 (hereinafter, the output current execution value of the first current 200 is referred to as “first current value”) is defined as “i ₁ ”. Further, the output voltage execution value of the first current 200 (hereinafter, the output current execution value is simply referred to as “voltage value”) is defined as “v ₁ ”. Further, the first current 200 is set so that the frequency becomes "f".

In the illustrated example, the voltage value “v ₁ ” is measured by the first resistor 104, the second resistor 105, the first rectifier circuit 106, and the like. The first current value "i ₁ " and the frequency "f" are values set in the CPU 101.

When the first current 200 flows through the wiring 110, a part of the current leaks to an output destination different from the load 111. If such a leakage destination is, for example, a first capacitor 112 and a second capacitor 113 connected in parallel to the load 111 as shown in the figure, an equivalent circuit considering the leakage destination is obtained. Then, a current leaks from the first current 200 to the leakage destinations indicated by the first capacitor 112 and the second capacitor 113. Hereinafter, the current flowing from the first current 200 to the leakage destination is generally referred to as "second current".

The first capacitor 112 has a configuration electrically equivalent to the leakage destination inside the power supply device 10. Then, the capacitance of the first capacitor 112 is defined as the first capacitance "C ₁ ". Further, of the first current 200, the second current flowing through the first capacitor 112 is referred to as "21st current 201". Further, the current value of the 21st current 201 is defined as the 21st current value "i ₂₁ ".

The second capacitor 113 has a configuration electrically equivalent to the leakage destination in the wiring 110. Then, the capacitance of the second capacitor 113 is defined as the second capacitance "C ₂ ". Further, of the first current 200, the second current flowing through the second capacitor 113 is referred to as "22nd current 202". Further, the current value of the 22nd current 202 is defined as the 22nd current value "i ₂₂ ".

Further, in the following description, _{the sum of the first} capacitance "C 1" and the second capacitance "C ₂ " is referred to as the total capacitance "C ₀ ".

Then, the final current flowing through the load 111 after the leakage of the second current as described above is referred to as "load current 204". Further, the current value of the load current 204 is defined as the load current value “i ₃ ”.

Therefore, each current value has the relationship as shown in the following equation (1).

1st current value i ₁ = 2nd current value + load current value i ₃
= 21st current value i ₂₁ + 22nd current value i ₂₂ + load current value i ₃ (1)

As shown in the above equation (1), the load current value "i ₃ " is a current value in which a _{part of the first current value "i 1} " is leaked as a second current and the leaked amount is reduced. be. In this way, the current value output to the load 111 has a leak in the middle, so the load current value "i ₃ " is smaller _{than the first current value "i 1" at the time of output.} Become. Therefore, in order to control the load current value "i ₃ ", first, the second current value is grasped.

As shown by the above equation (1), the second current value is the sum of the 21st current value “i ₂₁ ” and the 22nd current value “i ₂₂ ”. Therefore, by summing the 21st current value "i ₂₁ " and the 22nd current value "i ₂₂ ", the second current value, which is the total leakage current, can be specified.

The current value can be calculated by the following equation (2) based on Ohm's law.

Current value I = Voltage value V / Resistance value R
= Voltage value V x angular velocity ω x capacitance C
= Voltage value V x (2 x π x frequency f) x capacitance C (2)

Therefore, in order to calculate the second current value based on the above equation (2), the power supply device 10 measures and specifies the voltage value, frequency, and capacitance in the above equation (2).

Further, in the illustrated circuit configuration example, the driver 102, the transformer 103, the first resistor 104, the second resistor 105, the first rectifying circuit 106, the second rectifying circuit 107, and the third resistor 109 are as follows. It is electrically equivalent to such a circuit configuration.

FIG. 3 is a diagram showing an example of an equivalent circuit. Hereinafter, each configuration will be described with reference to the illustrated equivalent circuit.

The driver 102 serves as a bridge circuit and an LC filter to generate a sine wave.

The transformer 103 boosts the voltage. For example, the voltage value is boosted from AC ± 12V to AC ± 1500V and the like.

The first resistor 104 and the second resistor 105 are resistors for measuring a voltage value. The resistance values of the first resistor 104 and the second resistor 105 are sufficiently larger than the _first capacitance "C 1" and the second capacitance "C _2". .. For example, the resistance values of the first resistor 104 and the second resistor 105 are about several hundred MΩ.

The third resistor 109 is a resistor used for measuring _{the first current value “i 1”.}

The first rectifier circuit 106 and the second rectifier circuit 107 are a rectifier diode, an RC filter, and the like.

The CPU 101 is an example of a control device and an arithmetic unit.

The memory 108 is an example of a storage device.

For example, the power supply device 10 performs the following processing.

<Processing example with the load cut off>
It is desirable that the power supply device 10 measures the capacitance in a state where the load is cut off as follows.

FIG. 4 is a diagram showing an example of a circuit configuration in a state where the load is cut off. The circuit configuration shown is different from FIG. 2 in that there is no load 111. Hereinafter, description of the same configuration as in FIG. 2 will be omitted.

For example, the state in which the load is cut off is a state before the load 111 is installed, such as before the image forming apparatus 1 is shipped, or a state in which the load 111 is removed. On the other hand, when the load 111 is installed in the state shown in FIG. 4, the state shown in FIG. 2 is obtained. Then, the power supply device 10 performs the following processing in a state where the load as shown in the figure is cut off.

FIG. 5 is a diagram showing an example of processing performed in a state where the load is cut off.

In step S11, first, the load 111 is cut off. That is, the power supply device 10 has a circuit configuration as shown in FIG.

In step S12, the frequency "f" is set in the CPU 101.

In step S13, the CPU 101 receives an output instruction.

In step S14, the output of the first current 200 is started based on the control of the CPU 101.

In step S15, the first current value is measured. Hereinafter, the first current value measured with the load cut off will be referred to as the load cutoff current value “i ₁₀ ”.

In step S16, the voltage value is measured. Hereinafter, the voltage value measured with the load cut off will be referred to as the load cutoff voltage value “v ₁₀ ”.

In step S17, the total capacitance "C ₀ " is measured. Based on the above equation (2), the total capacitance "C ₀ " is calculated as follows by using the _{load breaking current value "i 10} " and the load breaking voltage value "v ₁₀ " measured in steps S15 and S16. It is calculated as in equation (3).

Total capacitance C ₀
= Load cutoff current value i ₁₀ / (Load cutoff voltage value v ₁₀ x 2 x π x frequency f) (3)

In step S18, the memory 108 stores the total capacitance “C ₀ ” measured in step S17.

As described above, for the measurement of the total capacitance "C _{0 ", the load cutoff current value "i 10} " and the load cutoff voltage value "v ₁₀ " measured in the state where the load is cut off are used. _{In this way, the total capacitance "C 0} " can be measured and stored under the condition that the influence of the variation due to the voltage tolerance and the voltage tolerance is small. Therefore, it is possible to improve the calculation accuracy of the calculation using the _{total capacitance "C 0" with the load described later connected.}

<Example with load connected>
FIG. 5 is a diagram showing an example of processing performed with a load connected.

In step S21, first, the load 111 is connected. That is, the power supply device 10 has a circuit configuration as shown in FIG.

In step S22, the frequency "f" is set in the CPU 101.

In step S23, the CPU 101 receives an output instruction.

In step S24, the output of the first current 200 is started based on the control of the CPU 101.

In step S25, the first current value “i ₁ ” is measured.

In step S26, the voltage value "v ₁ " is measured.

_{In step S27, the total capacitance “C 0} ” stored in the state where the load is cut off is read from the memory 108.

In step S28, the CPU 101 _{calculates the second current value “i 21} + i ₂₂ ”. Specifically, in the above equation (2), the current value "I" is set to "i ₂₁ + i ₂₂ ", and the capacitance "C" is set to "C ₀ " which is the result of reading in step S27. Further, assuming that the voltage value "V" is "v ₁ ", the second current value "i ₂₁ + i ₂₂ " can be calculated as shown in the following equation (4).

Second current value i ₂₁ + i ₂₂
= Voltage value v ₁ x (2 x π x frequency f) x total capacitance C ₀ (4)

Further, the frequency "f" in the above equation (4) is the frequency "f" set in step S22.

In step S29, the CPU 101 specifies the _{load current value “i 3”.} Due to the relationship of the above equation (1), the load current value "i ₃ " is as shown in the following equation (5) based on the first current value "i ₁ " and the second current value "i ₂₁ + i _22". It is calculated and specified in.

Load current value i ₃ = 1st current value i ₁ − (21st current value i ₂₁ + 22nd current value i ₂₂ ) (5)

That is, the load current value i ₃ can be specified _{by subtracting the second current value “i 21} + i ₂₂ ” which is the calculation result of step S28 from the first current value “i _{1” measured in step S25.}

The connection and disconnection of the load is not limited to the installation of the load and the switching before the installation. For example, connection and disconnection may be switched by a switch or the like.

In step S30, the CPU 101 controls the _{load current value “i 3”.} For example, the CPU 101 _{controls so that the load current value “i 3} ” becomes a substantially constant value. It should be noted that the constant value may not be completely matched, but may be controlled to be kept constant to the extent that an allowable range is set and falls within the allowable range.

<First comparative example>
FIG. 7 is a diagram showing a circuit configuration of the first comparative example. In the first comparative example, as compared with the circuit configuration shown in FIG. 2, the CPU 101 is the control circuit 301, and the first resistor 104, the second resistor 105, the first rectifier circuit 106, and the memory 108 are not provided. The difference is that.

Since there is a relationship as shown in the above equation (1), it is often difficult to directly control the _{load current value “i 3”.} For example, when the capacitance of the load 111 changes, the voltage value also changes. Therefore, the 21st current value "i ₂₁ " and the 22nd current value "i ₂₂ " also change. Therefore, it is difficult to control the load current value “i ₃ ” even if only the first current value “i _{1” is measured.}

For example, the following conditions will be described as an example.

Target value of load current value "i ₃ ": 2000 μArms
Total capacitance "C ₀ ": 15pF
Minimum capacitance of load 111 "C _3min ": 130pF
Maximum capacitance of load 111 "C _3max ": 330pF

When the load 111 has the minimum capacitance "C _{3 min} ", the state is as follows.

Load current value "i ₃ " = 2000 μArms × 130 pF / (15 pF + 130 pF)
= 1793 μArms
Second current value "i ₂₁ + i ₂₂ " = 2000 μArms-1793 μArms
= 207 μArms

On the other hand, when the load 111 has the maximum capacitance "C _3max ", the following state occurs.

Load current value "i ₃ " = 2000 μArms × 330 pF / (15 pF + 330 pF)
= 1913 μArms
Second current value "i ₂₁ + i ₂₂ " = 2000 μArms-1913 μArms
= 87 μArms

_{As shown in the above calculation result, the first current value "i 1} " detected by the HVP (High Voltage Power supply) is controlled to be the target value (in this example, "2000 μArms"). However, the load current value "i ₃ " changes due to the change in the load 111. The HVP is a high-voltage power supply device that can apply an AC voltage of a maximum of 3000 V (peak to peak) and a maximum of 2500 Hz because of charging by a charging roller 3 or the like. In the case of the maximum capacitance _{"C 3max"} minimum capacitance _{"C 3min"} shown in the "1913μArms-1793μArms = 120μArms (± 60μArms ) " partial changes will waking, the load current value _{"i 3"} Is not constant.

<Second comparative example>
FIG. 8 is a diagram showing a circuit configuration of the second comparative example. Compared with the first comparative example, the second comparative example is different in that the current detector 302 is added.

The current detector 302 is a measuring instrument that directly measures the _{load current value “i 3”.}

With such a configuration using an external core, the number of parts increases as the current detector 302 is added. Therefore, there are problems such as increasing the size of the circuit, increasing the cost, and securing the mounting place.

The current detector 302 is, for example, a coil for detection.

Further, the current detector 302 is mounted in the vicinity of the load 111. Therefore, the line length of the signal line from the current detector 302 tends to be long. Therefore, it is easily affected by noise, and it tends to be difficult to control using the signal transmitted by this signal line.

<Functional configuration example>
FIG. 9 is a diagram showing a functional configuration example of the power supply device. For example, the power supply device 10 has a functional configuration including a power supply unit 10F1, a storage unit 10F2, a voltage measurement unit 10F3, a frequency setting unit 10F4, a calculation unit 10F5, a current measurement unit 10F6, a specific unit 10F7, a control unit 10F8, and the like. .. Such a functional configuration is realized by, for example, a circuit configuration as shown in FIG. Further, it is desirable that the power supply device 10 has a functional configuration further including a correction unit 10F9.

For example, as shown in FIG. 5, the power supply device 10 calculates and specifies the _{total capacitance “C 0”.} Further, when the frequency “f” and the voltage value “v ₁ ” are obtained, the second current value “i ₂₁ + i ₂₂ ” of the second current leaking from the first current 200 can be calculated by the above equation (4). In this way, once the first current value "i ₁ " and the second current value "i ₂₁ + i _{22 " are determined, the load current value "i 3} " can be specified by calculating as in the above equation (5). can. The load current value “i ₃ ” specified in this way can also take into consideration the change in the capacitance “C _{3” of the load 111.} Therefore, with such a configuration, unlike the case of the first comparative example, the power supply device 10 can control the _{load current “i 3”.}

Further, with such a configuration, mounting parts such as a coil can be eliminated as in the second comparative example. That is, it can be realized by a simple circuit configuration composed of a resistor, a rectifier circuit, and the like. Therefore, the configuration can be inexpensive. Moreover, the circuit scale can be reduced.

Further, with such a configuration, the influence of noise can be minimized and precise control can be performed.

Further, it is desirable that the capacitance is corrected by the correction unit 10F9. First, the correction unit 10F9 detects temperature, humidity, or both temperature and humidity. Then, the correction unit 10F9 corrects the capacitance based on the temperature and humidity, or both the temperature and humidity. The characteristics of capacitance change depending on temperature and humidity. Therefore, it is desirable to correct it according to the current temperature and humidity. In this way, when the capacitance is corrected according to the temperature and humidity, or both the temperature and humidity, the second current value "i ₂₁ + i ₂₂ " can be calculated accurately.

_{Further, it is desirable that the second current value "i 21} + i ₂₂ " is calculated based on the voltage phase difference and the current phase difference. By calculating in this way, it is possible to separate the resistance component and the capacitor component.

Further, the voltage value may be measured based on the sub-winding of the transformer. With such a configuration, the number of parts for measuring the voltage value can be reduced, the price can be reduced, and the mounting area can be reduced. Specifically, the parts of the first resistor 104 and the second resistor 105 can be eliminated.

<Other Embodiments>
In addition, the resistor and the capacitor may be connected other than these.

In the above example, the power supply device is applied to the image forming device, but the power supply device may be applied to other devices.

The device described above does not have to be one device. That is, each device may be composed of a plurality of devices. For example, in the illustrated circuit, the storage device, arithmetic unit, resistor, capacitor, and the like may be composed of a plurality of devices.

It should be noted that all or part of each process according to the present invention may be realized by a program for causing a computer to execute a power supply control method. Therefore, when the power supply control method is executed based on the program, the arithmetic unit and the control unit of the computer perform the arithmetic and control based on the program in order to execute each process. In addition, the storage device of the computer stores the data used for the processing based on the program in order to execute each processing.

In addition, the program can be recorded and distributed on a computer-readable recording medium. The recording medium is a medium such as a magnetic tape, a flash memory, an optical disk, a magneto-optical disk, or a magnetic disk. In addition, the program can be distributed over telecommunication lines.

Although an example in the embodiment has been described above, the present invention is not limited to the above embodiment. That is, various modifications and improvements are possible within the scope of the present invention.

1 Image forming device 10 Power supply device 10F1 Power supply unit 10F2 Storage unit 10F3 Voltage measurement unit 10F4 Frequency setting unit 10F5 Calculation unit 10F6 Current measurement unit 10F7 Specific unit 10F8 Control unit 10F9 Correction unit 102 Driver 103 Transformer 104 First resistor 105 Second resistor Instrument 106 1st rectifying circuit 107 2nd rectifying circuit 108 Memory 109 3rd resistor 110 Wiring 111 Load 112 1st capacitor 113 2nd capacitor 200 1st current 201 21st current 202 22nd current 204 Load current C ₀ Total electrostatic Capacity f Frequency i ₁ First current value i ₃ Load current value i ₁₀ Load cutoff current value i ₂₁ 21st current value i ₂₂ 22nd current value v ₁ Voltage value v ₁₀ Load cutoff voltage value

Japanese Unexamined Patent Publication No. 9-218228

Claims (6)

A power supply unit that outputs the first current to supply power to the load,
A storage unit that stores the capacitance of the leakage destination through which the second current, which is a part of the first current, flows separately from the load.
A voltage measuring unit that measures the voltage value of the first current,
A frequency setting unit that sets the frequency of the first current, and
A calculation unit that calculates a second current value, which is a current value of the second current, based on the capacitance, the frequency, and the voltage value.
A current measuring unit that measures the first current value of the first current, and
A specific unit that specifies the load current value flowing through the load based on the first current value and the second current value, and
A power supply device including a control unit that controls the load current value to be constant. The power supply device according to claim 1, wherein the storage unit stores the capacitance calculated based on the frequency, the current value, and the voltage value of the first current in a state where the load is cut off. The power supply device according to claim 1 or 2, wherein the capacitance includes a first capacitance inside the power supply device and a second capacitance in the wiring used to supply the power. Detects temperature, humidity, or both temperature and humidity,
The power supply device according to any one of claims 1 to 3, further comprising a correction unit for correcting the capacitance based on the temperature, the humidity, or both the temperature and the humidity. The power supply device according to any one of claims 1 to 4, wherein the voltage measuring unit measures the voltage value based on the auxiliary winding of the transformer that outputs the first current. An image forming apparatus having the power supply device according to any one of claims 1 to 5.

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