JP7570705B2 - Noise reduction circuit and electrical equipment - Google Patents

Description

The present invention relates to a noise reduction circuit and an electrical device.

Home and commercial power supply voltages can be superimposed with noise, which can prevent electrical equipment from performing to its full potential. For example, audio equipment can sometimes not be able to output high-quality sound due to noise.

One possible solution is to reduce the noise in the power supply voltage using a noise reduction circuit, and then use the noise-reduced power supply voltage to drive the electrical equipment. An example of a noise reduction circuit is an LC low-pass filter. An LC low-pass filter can be used as a simple noise reduction circuit, as it cuts out the high-frequency noise components superimposed on the power supply voltage and allows only the low-frequency components to pass.

A method has also been proposed in which, instead of the power supply voltage, noise superimposed on the earth line is extracted and the extracted noise is used as an emergency power source (Patent Document 1).

JP 2016-86528 A

However, it is empirically known that when the noise of the power supply voltage supplied to an audio device is reduced by an LC low-pass filter, the inductor of the LC low-pass filter causes the sound output from the audio device to lose "power." In addition, the method of Patent Document 1 is a method for reducing noise superimposed on the earth wire, and this method cannot reduce power supply noise.

The present invention was made in consideration of this current situation, and aims to reduce noise superimposed on the power supply voltage without using an LC low-pass filter.

This application includes multiple means for solving at least some of the above problems, examples of which are as follows:

In order to solve the above problem, a noise reduction circuit according to one aspect of the present invention includes a transformer including a first power supply line, a second power supply line to which an AC voltage is applied between the first power supply line, a first capacitor having one end electrically connected to the first power supply line, a primary winding having one end electrically connected to the other end of the first capacitor and the other end electrically connected to the second power supply line, and a secondary winding magnetically coupled to the primary winding, a first terminal, and a second terminal electrically connected to one end of the secondary winding, and the first terminal and the second terminal are electrically connected to each other. a rectifier circuit that rectifies the current flowing between the first terminal and the second terminal; a second capacitor having one end electrically connected to the first terminal and the other end electrically connected to the other end of the secondary winding; a third terminal; and a fourth terminal electrically connected to the other end of the second capacitor, and a switch circuit that electrically connects the third terminal and the fourth terminal when the voltage between the two poles of the second capacitor becomes equal to or higher than a predetermined voltage; and an element having one end electrically connected to the third terminal and the other end electrically connected to the one end of the second capacitor.

The switch circuit has a thyristor with an anode terminal and a cathode terminal, the third terminal is one of the anode terminal and the cathode terminal, and the fourth terminal can be the other of the anode terminal and the cathode terminal.

The device may further include a control circuit that supplies a current to the gate of the thyristor when the voltage between the two electrodes of the second capacitor becomes equal to or greater than the predetermined voltage.

The element may be a light-emitting diode.

An electrical device according to another aspect of the present invention has a first power line, a second power line to which an AC voltage is applied between the first power line, a noise extraction unit that extracts noise superimposed on the first power line or the second power line, and an element drive unit that drives an element with the extracted noise.

The device may further include a housing, and the element may be a light-emitting diode that is visible from outside the housing.

There may be multiple outlets connected to each of the first power line and the second power line.

According to the present invention, it is possible to reduce noise superimposed on the power supply voltage without using an LC low-pass filter.

FIG. 1 is an external view showing an example of an electrical device according to the present embodiment. FIG. 2 is a diagram showing an example of a circuit diagram of an electric device according to the present embodiment. FIG. 3 is a diagram showing an example of a circuit diagram of a noise reduction circuit according to the present embodiment.

An embodiment of the present invention will be described below with reference to the drawings. In all drawings for describing an embodiment, the same components are generally given the same reference numerals, and repeated description will be omitted. In the following embodiments, the components (including element steps, etc.) are not necessarily essential, unless otherwise specified or considered to be obviously essential in principle. In addition, when "consists of A," "consists of A," "has A," or "includes A," it goes without saying that other elements are not excluded, except when it is specifically specified that only that element is included. Similarly, in the following embodiments, when referring to the shape, positional relationship, etc. of components, etc., it includes those that are substantially similar or similar to the shape, etc., except when it is specifically specified or considered to be obviously not essential in principle.

<Present embodiment>
FIG. 1 is an external view showing an example of an electrical device according to the present embodiment.

The electrical device 1 is a table tap, and has a housing 2, a power cable 3, and multiple outlets 4. The power cable 3 is a cable to which a household or commercial AC voltage is applied. Noise superimposed on the AC voltage is reduced by a noise reduction circuit, which will be described later. Then, each outlet 4 is supplied with the AC voltage with reduced noise in this manner.

The electrical device 1 is further provided with a light-emitting unit 5. As an example, the light-emitting unit 5 is a light-emitting diode that emits light in response to noise extracted by a noise reduction circuit described below, and is provided so as to be visible from outside the housing 2. For example, the housing 2 may be made of a translucent material, and the light-emitting unit 5 may be provided inside the housing 2, making the light-emitting unit 5 visible from outside through the housing 2. Alternatively, the light-emitting unit 5 may be provided on the outer surface of the housing 2, making the light-emitting unit 5 visible from outside the housing 2.

The light-emitting unit 5 emits light in response to the noise extracted from the AC voltage, so by making it visible from outside the housing 2 in this manner, the user can visually confirm that noise has been extracted.

Figure 2 shows an example of a circuit diagram of electrical device 1 according to this embodiment.

As shown in Fig. 2, the power cable 3 has a first power line 11 and a second power line 12. A household or commercial AC voltage V _AC having a frequency of 50 Hz to 60 Hz is applied between these power lines 11, 12. These power lines 11, 12 are connected to a noise reduction circuit 10 housed in the housing 2 (see Fig. 1).

The noise reduction circuit 10 is a circuit that reduces noise superimposed on each of the power supply lines 11, 12. Each of the power supply lines 11, 12 branches off to supply an AC voltage V _AC to each of the outlets 4. Since the noise of the AC voltage V _AC has been reduced by the noise reduction circuit 10, supplying an AC voltage from the outlet 4 to an audio device (not shown) makes it possible for the audio device to output high-quality sound with noise and other interference eliminated.

Figure 3 shows an example of a circuit diagram of the noise reduction circuit 10 according to this embodiment.

As shown in FIG. 3, the noise reduction circuit 10 includes a noise extraction unit 15 and an element driving unit 16 in addition to the light-emitting unit 5 described above.

The noise extraction unit 15 is a circuit that extracts high-frequency noise superimposed on the AC voltage V _AC , and is a high-pass filter in which first to third capacitors C1 to C3 are connected in parallel. The number of capacitors in the noise extraction unit 15 is not particularly limited. For example, the noise extraction unit 15 may be configured with one capacitor, or two or four or more capacitors connected in parallel may be used as the noise extraction unit 15.

In this example, one end 11a of the first capacitor C1 is electrically connected to the first power supply line 11. This allows noise superimposed on the AC voltage V _AC to pass through the noise extraction unit 15 and be output from the other end 11b of the first capacitor C1, thereby reducing the noise superimposed on the AC voltage V _AC . The same applies to the second to third capacitors C2 to C3.

The frequency of the noise extracted by the noise extraction unit 15 is not particularly limited, but in this example, the capacitances of the first to third capacitors C1 to C3 are set so that noise of several hundred kHz in the AM (Amplitude Modulation) wave band is extracted by the noise extraction unit 15. As an example, the capacitances of the first to third capacitors C1 to C3 are all set to 470 nF.

A fourth capacitor C4 and a first resistor R1 are provided between the first power supply line 11 and the second power supply line 12. The fourth capacitor C4 is a filter that reduces normal mode noise superimposed on the AC voltage _VAC , and has a capacitance of, for example, 470 nF. The first resistor R1 is a discharge resistor for the fourth capacitor C4, and has a resistance value of, for example, 330 kΩ.

On the other hand, the element driving unit 16 is a circuit that drives elements such as the light-emitting diodes of the light-emitting unit 5, and includes a transformer TR, a rectifier circuit 17, a fifth capacitor C5, and a switch circuit 19.

The transformer TR is a circuit element that boosts the voltage of the noise output from the other end 11b of the first capacitor C1. In this example, the transformer TR has a primary winding L1 and a secondary winding L2 that are magnetically coupled to each other. One end of the primary winding L1 is electrically connected to the other end 11b of the first capacitor C1, and the other end is electrically connected to the second power supply line 12. The ratio of the number of turns n1 of the primary winding L1 to the number of turns n2 of the secondary winding L2 is not particularly limited, but here it is set to n1:n2 = 7:75. By making n2>n1 in this way, noise that is boosted more than the primary side is output to the secondary side.

A Zener diode ZN is connected in parallel to the secondary winding L2. The Zener diode ZN protects the element driver 16 from overvoltage by making the potential difference between one end 16a and the other end 16b of the secondary winding L2 equal to or less than the clamp voltage.

The rectifier circuit 17 is a half-wave voltage doubler rectifier circuit that rectifies the current flowing between the first terminal 17a and the second terminal 17b in one direction. As an example, the rectifier circuit 17 includes a sixth capacitor C6, a first diode D1, and a second diode D2.

The sixth capacitor C6 is a charging capacitor that is charged with a voltage twice the potential difference across the secondary winding L2, and its capacitance is, for example, 100 nF. Here, the second terminal 17b, which is one end of the sixth capacitor C6, is electrically connected to one end 16a of the secondary winding L2.

In addition, each of the diodes D1 and D2 is a rectifier diode. In this example, the cathode terminal of the first diode D1 is electrically connected to the other end 17c of the sixth capacitor C6. In addition, the anode terminal of the first diode D1 is electrically connected to the other end 16b of the transformer TR.

The cathode terminal of the second diode D2 functions as the first terminal 17a, and the anode terminal is electrically connected to the other end 17c of the sixth capacitor C6.

On the other hand, the fifth capacitor C5 is a circuit element that, together with the second resistor R2, constitutes an RC charging circuit. As an example, the resistance value of the second resistor R2 is 100 kΩ, and the capacitance of the fifth capacitor C5 is 4.7 μF. Here, one end 16c of the fifth capacitor C5 is electrically connected to the first terminal 17a via the second resistor R2. In addition, the other end 16d of the fifth capacitor C5 is electrically connected to the other end 16b of the secondary winding L2.

The fifth capacitor C5 is connected in parallel with the seventh capacitor C7 via the third resistor R3. The third resistor R3 and the seventh capacitor C7 form an RC charging circuit to prevent chattering of the switch circuit 19. As an example, the resistance of the third resistor R3 is 100 kΩ, and the capacitance of the seventh capacitor C7 is 100 nF.

The switch circuit 19 is a circuit for switching the current supplied to the light-emitting unit 5. For example, the switch circuit 19 includes a control IC 18, a fourth resistor R4, and a thyristor TH.

The thyristor TH is a circuit element that is turned on when a current is supplied to the gate 19c, with the anode terminal 19a and the cathode terminal 19b being electrically connected. The cathode terminal 19b is an example of a fourth terminal, and is electrically connected to the other end 16d of the fifth capacitor C5. The anode terminal 19a is an example of a third terminal, and is electrically connected to the light-emitting unit 5. Note that the direction of the current rectified by the rectifier circuit 17 may be reversed to electrically connect the anode terminal 19a to the other end 16d of the fifth capacitor C5, and the cathode terminal 19b to the light-emitting unit 5.

The control IC (Integrated Circuit) 18 is an example of a control circuit and includes a fifth terminal 18a and a sixth terminal 18b. The fifth terminal 18a is electrically connected to one end 16c of the fifth capacitor C5 via a third resistor R3. The sixth terminal 18b is electrically connected to the other end 16d of the fifth capacitor C5.

The potential difference between the fifth terminal 18a and the sixth terminal 18b is equal to the voltage V _C between the two electrodes of the fifth capacitor C5. The control IC 18 monitors the voltage V _C , and when the charging of the fifth capacitor C5 progresses and the voltage V _C becomes equal to or higher than a predetermined voltage V _TH , it supplies a current to the gate 19c via the fourth resistor R4. The fourth resistor R4 is a resistor for limiting the current supplied to the gate 19c, and has a resistance value of, for example, 10 kΩ.

The light-emitting unit 5 includes a first light-emitting diode LED1 and a second light-emitting diode LED2 that are connected in parallel to each other. The number of light-emitting diodes included in the light-emitting unit 5 is not limited to two. For example, the light-emitting unit 5 may be configured with one light-emitting diode, or three or more light-emitting diodes connected in series or parallel may be used as the light-emitting unit 5.

Here, the anode terminal of the first light-emitting diode LED1 is electrically connected to one end 16c of the fifth capacitor C5 via the fifth resistor R5. Also, the cathode terminal of the first light-emitting diode LED1 is electrically connected to the anode terminal 19a of the thyristor TH.

Similarly, the anode terminal of the second light-emitting diode LED2 is electrically connected to one end 16c of the fifth capacitor C5 via the sixth resistor R6. And, the cathode terminal of the second light-emitting diode LED2 is electrically connected to the anode terminal 19a of the thyristor TH.

The fifth resistor R5 and the sixth resistor R6 are resistors for limiting the current supplied to the first light-emitting diode LED1 and the second light-emitting diode LED2, respectively, and have a resistance value of, for example, 10 kΩ.

According to the noise reduction circuit 10, the noise superimposed on each of the power lines 11 and 12 is extracted by the noise extraction unit 15, and then the voltage of the noise is boosted by the transformer TR. The boosted noise has its AC component cut by the rectifier circuit 17, and then charges the fifth capacitor C5. When the potential difference V _C between the two electrodes of the fifth capacitor C5 becomes equal to or greater than a predetermined voltage V _TH , the control IC 18 supplies a gate current to the thyristor TH, and the anode terminal 19 a and the cathode terminal 19 b of the thyristor TH are electrically connected. This causes the fifth capacitor C5 to discharge, and the discharge current causes the LEDs 1 and 2 to emit light.

This makes it possible to reduce noise superimposed on each of the power supply lines 11, 12, and therefore to supply AC voltage V _{AC with reduced noise to each of the outlets 4 (see FIG. 1). Moreover, since the noise reduction circuit 10 does not have an LC low-pass filter, for example, by supplying AC voltage V AC from} each of the outlets 4 to an audio device (not shown), the "power" of the sound output from the audio device can be maintained.

In addition, because the extracted noise is used as the power to light the light-emitting unit 5, the light-emitting unit 5 lights up when noise is extracted, allowing the user to visually confirm that the noise has been extracted. Note that if the user does not need to confirm that the noise has been extracted, a circuit element that consumes the power of the noise may be used in place of the light-emitting unit 5. Examples of such circuit elements include an inductor or resistor.

Furthermore, in this example, a thyristor TH is used as the switching element in the switch circuit 19. Once the thyristor TH is turned on, it does not turn off until the potential difference between the anode terminal 19a and the cathode terminal 19b becomes zero. Therefore, once the thyristor TH is turned on by the extracted noise, the thyristor TH is maintained in the on state as long as the potential difference between the anode terminal 19a and the cathode terminal 19b does not become zero, and subsequent noise can cause the LEDs 1 and 2 of the light-emitting section 5 to emit light. This eliminates the need to turn on the switch circuit 19 every time noise is extracted, and therefore the number of switching times of the switch circuit 19 can be significantly reduced, and noise can be efficiently converted into light energy.

The present invention is not limited to the above-described embodiment and modifications, and various other modifications are possible. For example, the above-described embodiment and modifications have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. In addition, it is possible to replace part of one modification with another modification, or to combine modifications.

1...electrical device, 2...housing, 3...power cable, 4...outlet, 5...light emitting unit, 10...noise reduction circuit, 11...first power line, 11a...one end, 11b...other end, 12...power line, 12...second power line, 15...noise extraction unit, 16...element drive unit, 16a...one end, 16b...other end, 16c...one end, 16d...other end, 17...rectifier circuit, 17a...first terminal, 17b...second terminal, 17c...other end, 18a...fifth terminal, 18b...sixth terminal, 19...switch circuit, 19a...anode terminal, 19b...cathode terminal, 19c...gate.

Claims (7)

A first power line;
a second power supply line to which an AC voltage is applied between the second power supply line and the first power supply line;
a first capacitor having one end electrically connected to the first power line;
a transformer including a primary winding, one end of which is electrically connected to the other end of the first capacitor and the other end of which is electrically connected to the second power supply line, and a secondary winding, which is magnetically coupled to the primary winding;
a rectifier circuit having a first terminal and a second terminal electrically connected to one end of the secondary winding, the rectifier circuit rectifying a current flowing between the first terminal and the second terminal;
a second capacitor having one end electrically connected to the first terminal and the other end electrically connected to the other end of the secondary winding;
a switch circuit having a third terminal and a fourth terminal electrically connected to the other end of the second capacitor, the switch circuit electrically connecting the third terminal and the fourth terminal when a voltage between both electrodes of the second capacitor becomes equal to or higher than a predetermined voltage;
an element having one end electrically connected to the third terminal and the other end electrically connected to the one end of the second capacitor;
A noise reduction circuit having a 2. The noise reduction circuit according to claim 1,
the switch circuit includes a thyristor having an anode terminal and a cathode terminal;
the third terminal is one of the anode terminal and the cathode terminal;
the fourth terminal is the other of the anode terminal and the cathode terminal;
Noise reduction circuitry. 3. The noise reduction circuit according to claim 2,
a control circuit that supplies a current to a gate of the thyristor when the voltage across the second capacitor becomes equal to or higher than the predetermined voltage.
Noise reduction circuitry. 4. A noise reduction circuit according to claim 1,
the element is a light emitting diode;
Noise reduction circuitry. A first power line;
a second power supply line to which an AC voltage is applied between the second power supply line and the first power supply line;
a noise extraction unit that extracts noise superimposed on the first power line or the second power line;
An element driving unit that drives an element using the extracted noise,
The noise extraction unit
a first capacitor having one end electrically connected to the first power supply line;
The element driving unit is
a transformer including a primary winding, one end of which is electrically connected to the other end of the first capacitor and the other end of which is electrically connected to the second power supply line, and a secondary winding, which is magnetically coupled to the primary winding;
a rectifier circuit having a first terminal and a second terminal electrically connected to one end of the secondary winding, and rectifying a current flowing between the first terminal and the second terminal;
The noise extraction unit
a second capacitor having one end electrically connected to the first terminal and the other end electrically connected to the other end of the secondary winding;
The element driving unit is
a switch circuit having a third terminal and a fourth terminal electrically connected to the other end of the second capacitor, and electrically connecting the third terminal and the fourth terminal when a voltage between both electrodes of the second capacitor becomes equal to or higher than a predetermined voltage;
one end of the element is electrically connected to the third terminal and the other end is electrically connected to the one end of the second capacitor;
Electrical equipment. 6. An electrical device according to claim 5,
Further comprising a housing;
The element is a light emitting diode visible from outside the housing.
Electrical equipment. The electrical device according to claim 5 or 6,
a plurality of outlets connected to each of the first power line and the second power line;
Electrical equipment.

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