JP6750232B2 - Bias power supply circuit for electrostatic speaker and speaker device - Google Patents

Description

The present invention relates to an electrostatic speaker bias power supply circuit for supplying a bias voltage to an electrostatic speaker, and a speaker device including the electrostatic speaker bias power supply circuit.

Patent Document 1 discloses an electrostatic speaker having a fixed pole and a movable pole, and a drive circuit. In the drive circuit described in Patent Document 1, a DC high voltage power supply (bias power supply) is connected to a signal line that supplies a drive signal to the movable pole. As a result, the drive circuit described in Patent Document 1 supplies a predetermined bias voltage between the movable pole and the fixed pole.

Further, Patent Document 2 discloses a condenser headphone and a drive circuit. The drive circuit described in Patent Document 2 includes a booster circuit that generates a bias voltage to be supplied to the condenser headphones. The booster circuit is connected to the DC power supply. The booster circuit boosts the DC voltage from the DC power supply to generate a bias voltage and supplies the bias voltage to the condenser headphones.

JP 2001-197596 A JP, 2006-041569, A

The bias power supply of the electrostatic speaker requires a high-voltage (for example, about 1000 V) DC power supply. Therefore, the bias power supply circuit needs to be provided with an insulating transformer, a rectifier circuit, and a DC-DC converter in order to obtain a high-voltage DC power supply from a low-voltage (for example, 100V or 200V) single-phase AC power supply. However, in order to obtain a high-voltage DC power supply of about 1000 V, the volume of the insulating transformer and the DC-DC converter is large and heavy. Therefore, the conventional bias power supply circuit is not suitable for being built in an electrostatic speaker characterized by being thin and light.

An object of the present invention is to provide a bias power supply circuit suitable for an electrostatic speaker and a speaker device.

A bias power supply circuit for an electrostatic speaker of the present invention is connected between a first power supply line, a second power supply line, and the first power supply line and the second power supply line, and boosts and rectifies a single-phase AC power supply. Boost rectifier circuit, a first output line which is an output line of the boost rectifier circuit, a second output line connected to the first power supply line or the second power supply line, the first output line and the first output line. A current limiting circuit connected to the two output lines.

As described above, the boost rectifier circuit directly generates a high-voltage (for example, about 1000V) DC power supply from a 100V or 200V single-phase AC power supply. Therefore, a DC-DC converter is not required, and a bias power supply circuit suitable for a thin and lightweight electrostatic speaker can be provided.

Further, the electrostatic speaker bias power supply circuit of the present invention directly generates a high-voltage DC power supply from a single-phase AC power supply, but the current limiting circuit connected to the first output line and the second output line supplies a current value. Therefore, electric shock can be prevented. The electrostatic speaker requires a high-voltage bias power supply of about 1000 V, but can be sufficiently driven even at a very low current value (for example, 0.1 mA or less). Therefore, the electrostatic speaker bias power supply circuit can significantly reduce the current value in the current limiting circuit to prevent electric shock.

The current limiting circuit uses an insulating transformer or a resistor. When the resistor is used, the insulating transformer is not necessary, and the size and weight can be further reduced. When the insulating transformer is used, the supply voltage can be easily adjusted.

According to the present invention, a bias power supply circuit suitable for an electrostatic speaker can be realized.

It is a block diagram which shows the structure of a speaker apparatus. It is a circuit diagram of a bias power supply circuit. It is a circuit diagram of a circuit for connection and a block diagram of an electrostatic speaker. 17 is a block diagram showing the configuration of a speaker device according to Application Example 1. FIG. It is a circuit diagram of a circuit for connection and a block diagram of an electrostatic speaker. 17 is a block diagram showing a configuration of a speaker device according to an application example 2. FIG. 17 is a block diagram showing a configuration of a speaker device according to an application example 2. FIG.

FIG. 1 is a block diagram showing the configuration of the speaker device. FIG. 2 is a circuit diagram of a bias power supply circuit, and FIG. 3 is a circuit diagram of a connection circuit and a configuration diagram of an electrostatic speaker.

The speaker device 1 includes a bias power supply circuit 25, an amplifier 29, and a speaker unit 10. The speaker unit 10 includes a connection circuit 27 and an electrostatic speaker 100. The bias power supply circuit 25, the amplifier 29, and the electrostatic speaker 100 are connected to the connection circuit 27. The bias power supply circuit 25 is connected to a single-phase AC power supply.

As shown in FIG. 2, the bias power supply circuit 25 includes a resistor 50, a resistor 51, a resistor 80, and a boost rectifier circuit 60.

The first power supply line VL1 and the second power supply line VL2 are connected to one end (input side) of the booster rectifier circuit 60. The resistor 50 is connected to the other end (output side) of the boost rectifier circuit 60. The first power supply line VL1 and the second power supply line VL2 are power supply lines connected to a single-phase AC power supply.

The first power supply line VL1 is connected to the boost rectifier circuit 60 via the resistor 80. The second power supply line VL2 is connected to the boost rectifier circuit 60 and the resistor 51, respectively. The resistor 80 is not an essential component.

The boost rectifier circuit 60 includes eight capacitors (capacitors 31, 32, 33, 34, 35, 36, 37, 38) and eight diodes (diodes 41, 42, 43, 44, 45, 46, 47, 48). I have it.

A series circuit including a capacitor 31 that is a first capacitor and a diode 41 that is a first diode is connected between the first power supply line VL1 and the second power supply line VL2. One end of the capacitor 31 is connected to the first power supply line VL1 and the other end is connected to the cathode of the diode 41. The anode of the diode 41 is connected to the second power supply line VL2.

A series circuit including a capacitor 32 that is a second capacitor and a diode 42 that is a second diode is connected in parallel to the diode 41. One end of the capacitor 32 is connected to the second power supply line VL2 and the anode of the diode 41. The other end of the capacitor 32 is connected to the cathode of the diode 42. The anode of the diode 42 is connected to the cathode of the diode 41.

When the second power supply line VL2 side has a higher potential than the first power supply line VL1 side, the diode 41 becomes conductive and the capacitor 31 is charged. The capacitor 31 is charged with the peak value (41 V) of the voltage (100 Vrms) of the single-phase AC power supply. On the other hand, when the first power supply line VL1 side has a higher potential than the second power supply line VL2 side, the diode 42 becomes conductive and the capacitor 32 is charged. The peak value (141V) of the single-phase AC power supply is further added to the capacitor 32 with respect to the voltage charged in the capacitor 31. Therefore, the voltage charged in the capacitor 32 is about 2.8 (1.4×2) times the voltage of the single-phase AC power supply.

Hereinafter, similarly, the boost rectifier circuit 60 includes eight capacitors (capacitors 31, 32, 33, 34, 35, 36, 37, 38) and eight diodes (diodes 41, 42, 43, 44, 45, 46). , 47, 48), the voltage of the single-phase AC power supply is boosted and rectified to a DC voltage which is about 8 times the peak value (141 V). Therefore, the AC voltage input to the boost rectifier circuit 60 is converted into a DC voltage (1128V) that is about eight times as high.

In this example, the bias power supply circuit 25 includes eight capacitors (capacitors 31, 32, 33, 34, 35, 36, 37, 38) and eight diodes (diodes 41, 42, 43, 44, 45, 46). , 47, 48), a method of obtaining a DC power source of about 8 times the voltage from a single-phase AC power source is shown, but a desired DC voltage can be obtained by changing the number of capacitors and diodes.

As shown in FIG. 3, the first output line OL1 of the boost rectifier circuit 60 is connected to the bias voltage supply line SL20 of the connection circuit 27. The second output line OL2 connected to the second power supply line VL2 is connected to the second drive signal line SL22 (or the first drive signal line SL21) to which the audio signal is supplied from the amplifier 29.

However, as shown in FIG. 2, the resistor 50 is connected to the first output line OL1 of the boost rectifier circuit 60, and the resistor 51 is connected to the second output line OL2 which is the second power supply line VL2. Has been done. Therefore, the current values flowing through the first output line OL1 and the second output line OL2 of the bias power supply circuit 25 are limited by the resistor 50 and the resistor 51. The resistance values of the resistor 50 and the resistor 51 are set so that the current value is sufficient to prevent electric shock (for example, 0.1 mA or less).

As shown in FIG. 3, the connection circuit 27 includes a bias capacitor 65, a resistor 71, a resistor 72, and a resistor 90. The electrostatic speaker 100 also includes a movable electrode 110, a first fixed electrode 121, and a second fixed electrode 122.

The movable electrode 110, the first fixed electrode 121, and the second fixed electrode 122 are flat film electrodes. The movable electrode 110, the first fixed electrode 121, and the second fixed electrode 122 are arranged such that their flat film surfaces are parallel to each other in the state where no drive signal is supplied. The movable electrode 110 is arranged between the first fixed electrode 121 and the second fixed electrode 122.

The resistor 71 and the resistor 72 are connected between the first drive signal line SL21 and the second drive signal line SL22 to which the audio signal is supplied from the amplifier 29. It is desirable that the resistors 71 and 72 have the same resistance value. It is desirable to connect a series resistor to the first drive signal line SL21 and the second drive signal line SL22. As a result, the oscillation of the amplifier 29 can be prevented and the current value can be limited. However, it is desirable that the resistance value is, for example, about several hundreds Ω to 1 KΩ in consideration of the influence on the high frequency band of the audio signal and the influence of heat generation.

The bias voltage supply line SL20 is connected to a connection point between the resistors 71 and 72. The bias voltage supply line SL20 is connected to the movable electrode 110 of the electrostatic speaker 100 via the resistor 90.

The bias capacitor 65 is charged by the DC power supply supplied from the bias power supply circuit 25. As a result, a potential difference of about 8 times that of the single-phase AC power source is generated at both ends of the bias capacitor 65.

Therefore, a DC voltage (bias voltage) that is about eight times that of the single-phase AC power supply is applied between the movable electrode 110 and the first fixed electrode 121 and between the movable electrode 110 and the second fixed electrode 122.

With the above configuration, the bias power supply circuit 25 can generate a high-voltage bias voltage and drive the electrostatic speaker 100 by push-pull without providing an insulating transformer and a DC-DC converter.

The bias power supply circuit 25, directly from the single-phase AC power source, that generates a direct current power supply of the high pressure. However, since the current value is significantly limited (for example, 0.1 mA or less) by the resistors 50 and 51 connected to the first output line OL1 and the second output line OL2, the user is grounded. There is no risk of electric shock if you touch the line. The electrostatic speaker 100 needs a high bias voltage of about 1000 V, but even if the current value is 1 mA or less, it is sufficient to charge the bias capacitor 65 and drive the movable electrode 110. The required sound pressure can be obtained.

Therefore, the bias power supply circuit 25 becomes a bias power supply circuit suitable for the thin electrostatic speaker 100.

Further, in the speaker device 1, since the bias power supply circuit 25 generates a high-voltage bias voltage from the single-phase AC power supply, the amplifier 29 is a low impedance amplifier (for example, about 2 to 16Ω) for a general dynamic speaker (for audio). Amplifier) can be used.

In the above-described embodiment, as an example of the current limiting circuit, the mode in which the resistors are connected to the first output line OL1 and the second output line OL2 is shown. However, for example, between the connection circuit 27 and the amplifier 29 ( A mode in which an insulating transformer is inserted in a line to which an audio signal is supplied) may be used. However, when the insulating transformer is inserted, it is preferable that the bias power supply circuit 25, the connection circuit 27, and the electrostatic speaker 100 are covered with an insulated enclosure. In the aspect in which the insulation transformer is inserted, the voltage of the audio signal can be adjusted by adjusting the winding ratio of the insulation transformer. Generally, the output voltage of a low impedance amplifier is lower than the output voltage of a high impedance amplifier (about 70V or 100V) (for example, about several tens of volts), but an audio signal is output by inserting an isolation transformer. Since the pressure can be increased, a louder sound can be reproduced.

In the single-phase AC power supply, the first power supply line VL1 is AC100V and the second power supply line VL2 is grounded, and the first power supply line VL1 is grounded and the second power supply line VL2 is AC100V. There are cases where That is, depending on the polarity of the connection (direction of connection of the outlet), the first power supply line VL1 may be AC100V and the second power supply line VL2 may be AC100V.

When the first power supply line VL1 is AC100V, AC100V is superimposed on the output of the boost rectifier circuit 60, but the AC component is removed by the high-frequency blocking filter configured by the resistor 50 and the capacitor 65. To be done. Therefore, the output of the step-up rectifier circuit 60 is almost only a DC component. On the other hand, when the first power supply line VL1 is grounded, AC100V is not superimposed, so that the output of the boost rectifier circuit 60 is naturally a DC voltage. The AC 100V of the second signal line VL2 is connected to the signal line SL22 in the connection circuit 27 and is applied to the midpoint of the second resistor 71 and the resistor 72. Since the capacitor 65 in the connection circuit 27 functions as a high-frequency blocking filter, the AC component is removed also in this case. Therefore, the bias power supply circuit 25 does not depend on the polarity of connection.

Next, FIG. 4 is a block diagram showing a configuration of the speaker device 1A according to the application example 1. FIG. 5 is a circuit diagram of a connection circuit and a configuration diagram of an electrostatic speaker. The same components as those shown in FIGS. 1 and 3 are designated by the same reference numerals and the description thereof will be omitted.

The speaker device 1A includes a dynamic speaker 200 in addition to the configuration of the speaker device 1. The dynamic speaker 200 is connected to the amplifier 29 via the connection circuit 27A.

The connection circuit 27A branches the audio signal input from the amplifier 29 and supplies it to the dynamic speaker 200. As described above, in the speaker device 1A, the amplifier 29 for the dynamic speaker also serves as the amplifier of the electrostatic speaker 100.

Alternatively, the amplifier 29 and the dynamic speaker 200 may be directly connected. In this case, the audio circuit does not need to be branched in the connection circuit 27A (that is, the same circuit as the connection circuit 27 shown in FIG. 3).

Next, FIG. 6A is a block diagram showing the configuration of the speaker device 1B according to the second application example. In this example, the speaker unit 10A includes an electrostatic speaker 100, a dynamic speaker 200, and a connecting circuit 27A. The difference from the speaker device 1A shown in FIGS. 4 and 5 is that the speaker unit 10A is a speaker unit 10A in which an electrostatic speaker 100, a dynamic speaker 200, and a connection circuit 27A are integrated. is there.

Further, like the speaker device 1C shown in FIG. 6B, the speaker unit in which the electrostatic speaker 100, the dynamic speaker 200, the connection circuit 27A, the bias power supply circuit 25, and the amplifier 29 are integrated as the speaker unit 10B. 10C may be configured. Thus, the single-layer AC power supply for the bias power supply circuit 25 can also be used as the single-phase AC power supply for the amplifier 29. Therefore, it is not necessary to separately provide the bias power supply circuit 25 with a connection terminal for the single-layer AC power supply.

Alternatively, as in the speaker device 1D shown in FIG. 7, a network circuit 205, which is a band dividing unit, may be provided in a stage subsequent to the amplifier 29. The network circuit 205 shown in FIG. 7 divides the band of the audio signal supplied from the amplifier 29 and supplies it to the connection circuit 27 and the dynamic speaker 200. The network circuit 205 supplies the high frequency side to the connection circuit 27 and supplies the low frequency side to the dynamic speaker 200.

In the speaker unit 10C shown in FIG. 7, in the case where an insulation transformer is inserted instead of a resistor as an example of the current limiting circuit, the insulation transformer is connected between the network circuit 205 and the connection circuit 27. To be done. Alternatively, the isolation transformer may be connected between the amplifier 29 and the network circuit 205.

As described above, when the insulating transformer is used, the bias voltage can be adjusted by adjusting the winding ratio. Therefore, in the mode including the insulating transformer, it becomes easy to adjust the sound pressure ratio between the electrostatic speaker 100 and the dynamic speaker 200 in the modes shown in FIGS. 4 to 7. Even if audio signals of the same level are supplied, when the bias voltage is increased, the sound pressure of the electrostatic speaker 100 is increased, and when the bias voltage is decreased, the sound pressure of the electrostatic speaker 100 is increased. The sound pressure is low.

Further, in any case of using the insulating transformer or the resistor as the current limiting circuit, the gap between the movable electrode 110 and the first fixed electrode 121, and the movable electrode 110 and the second fixed electrode 122. The sound pressure ratio between the electrostatic speaker 100 and the dynamic speaker 200 can be adjusted by adjusting the gap between Even if audio signals of the same level are supplied, the sound pressure of the electrostatic speaker 100 becomes high when the gap is made small, and the sound pressure of the electrostatic speaker 100 becomes large when the gap is made large. Will be lower. Since the low frequency sound is mainly output from the dynamic speaker 200, there is no problem even if the sound pressure in the low frequency range output from the electrostatic speaker 100 is reduced by reducing the gap.

Also, the sound pressure ratio between the electrostatic speaker 100 and the dynamic speaker 200 can be adjusted by inserting an attenuator that reduces the level of the audio signal.

OL1... First output line OL2... Second output line SL20... Bias voltage supply line SL21... First drive signal line SL22... Second drive signal line VL1... First power supply line VL2... Second power supply line 1, 1A, 1B, 1C, 1D... Speaker device 1010A, 10B, 10C... Speaker unit 25... Bias power supply circuit 27, 27A... Connection circuit 29... Amplifier 31, 32, 33, 34, 35, 36, 37, 38... Capacitor 41, 42, 43, 44, 45, 46, 47, 48... Diodes 50, 51, 71, 72, 80, 90... Resistor 60... Boost rectifier circuit 65... Bias capacitor 100... Electrostatic speaker 110... Movable electrode 121... 1 fixed electrode 122... 2nd fixed electrode 200... dynamic speaker 205... network circuit

Claims (7)

A boost rectifier circuit that is connected to the first power line and the second power line of the single-phase AC power supply and that boosts and rectifies the single-phase AC power supply without going through the insulating transformer
A first output line which is an output line of the boost rectifier circuit;
A second output line connected to the first power supply line or the second power supply line;
A current limiting circuit connected to the first output line and the second output line;
A bias power supply circuit for an electrostatic speaker, comprising:
The boost rectifier circuit is
A first capacitor,
A cathode connected to the first capacitor, a first diode connected between the first power supply line and the second power supply line,
A second capacitor connected to the anode of the first diode;
A cathode connected to the second capacitor, a second diode connected between the first power supply line and the second power supply line,
Equipped with
The first output line is connected to a bias voltage supply line of an electrostatic speaker,
The bias power supply circuit for an electrostatic speaker, wherein the second output line is connected to a first drive signal line or a second drive signal line to which an audio signal is supplied from a dynamic speaker drive amplifier . A boost rectifier circuit that is connected to the first power line and the second power line of the single-phase AC power supply and boosts and rectifies the single-phase AC power supply;
A first output line which is an output line of the boost rectifier circuit;
A second output line connected to the first power supply line or the second power supply line;
A current limiting circuit connected to the first output line and the second output line;
A bias power supply circuit for an electrostatic speaker, comprising:
The boost rectifier circuit is
A first capacitor,
A cathode connected to the first capacitor, a first diode connected between the first power supply line and the second power supply line,
A second capacitor connected to the anode of the first diode;
A cathode connected to the second capacitor, a second diode connected between the first power supply line and the second power supply line,
Equipped with
The first output line is connected to a bias voltage supply line of an electrostatic speaker,
The second output line is connected to a first drive signal line or a second drive signal line to which an audio signal is supplied from a dynamic speaker drive amplifier. An electrostatic speaker bias power supply circuit. The bias power supply circuit for an electrostatic speaker according to claim 1 or 2, wherein the current limiting circuit comprises an insulating transformer or a resistor. Bias power supply circuit for electrostatic speaker, electrostatic speaker, dynamic speaker, drive amplifier for supplying audio signal to the dynamic speaker and electrostatic speaker, and bias voltage for the electrostatic speaker A speaker device comprising: a bias voltage supply line; and a first drive signal line and a second drive signal line for supplying an audio signal from the drive amplifier to the electrostatic speaker,
The bias power supply circuit for the electrostatic speaker is
A boost rectifier circuit that is connected to the first power line and the second power line of the single-phase AC power supply and that boosts and rectifies the single-phase AC power supply without going through the insulating transformer
A first output line which is an output line of the boost rectifier circuit;
A second output line connected to the first power supply line or the second power supply line;
A current limiting circuit connected to the first output line and the second output line;
Equipped with
The boost rectifier circuit is
A first capacitor,
A cathode connected to the first capacitor, a first diode connected between the first power supply line and the second power supply line,
A second capacitor connected to the anode of the first diode;
A second diode having a cathode connected to the second capacitor and connected between the first power supply line and the second power supply line;
Equipped with
The bias voltage supply line is connected to the first output line ,
A speaker device in which the second output line is connected to the first drive signal line or the second drive signal line. A bias power supply circuit for an electrostatic speaker according to any one of claims 1 to 3 ,
An electrostatic speaker,
A dynamic speaker,
A drive amplifier that supplies an audio signal to the dynamic speaker and the electrostatic speaker;
A bias voltage supply line connected to the first output line and supplying a bias voltage to the electrostatic speaker;
A first drive signal line and a second drive signal line for supplying an audio signal from the drive amplifier to the electrostatic speaker;
A speaker device comprising: the first drive signal line or the second drive signal line, to which the second output line is connected. The speaker device according to claim 4 or 5 , wherein the first power supply line and the second power supply line of the single-phase AC power supply are further connected to the drive amplifier. 7. The speaker device according to claim 4 , further comprising a band division unit that divides a band of an audio signal supplied to the dynamic speaker and an audio signal supplied to the drive amplifier.

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