TWI424682B - Electret amplifier - Google Patents

Description

Electret amplifier

The present invention relates to an electret amplifier, and more particularly to a portable electret amplifier that incorporates an audio source that provides an audio signal.

The traditional audio system mainly consists of three parts: an audio source that provides audio signals, an audio amplifier, and a speaker. The speakers are mostly moving coils and electrostatic speakers, and the electret amplifier of the present invention can be used to push electret speakers.

The main function of the traditional audio amplifier is to amplify the weak audio signal of the audio source to obtain enough power to push the speaker, and enhance the ability to prevent noise interference to the audio signal, so that the audio signal can be output with low distortion and amplified to the speaker. So that the user can hear the original sound. Since the moving coil type speaker needs high current driving, and the signal distortion is easily caused by electromagnetic interference and transmission loss during high current signal transmission, high quality audio wire is required to reduce the distortion caused by signal transmission. In addition, in order to improve efficiency, the sound system must achieve impedance matching, so that the audio amplifier input can get the maximum power from the audio source, and the output can also transmit the maximum output power of the amplifier to the speaker. However, since the principle of operation of the speaker is different from that of the electret speaker of the present invention, the conventional acoustic amplifier cannot be used to push the electret speaker of the present invention.

The electrostatic speaker and the electret speaker of the present invention both use electrostatic force to push the speaker. However, the acoustic amplifier of the electrostatic speaker must additionally provide a high-voltage DC power supply to the speaker to form an electrostatic field required to push the diaphragm, so only Suitable for fixed placement, and most of the existing audio amplifiers of the existing electrostatic speakers directly boost the voltage from the low voltage to the high voltage required by the speaker (about 200Vrms or more), so the conversion efficiency is poor and the power consumption is large. There is still room for improvement in application, and an audio amplifier with high efficiency, low power consumption and portability is urgently needed to improve the convenience of use.

The amplifier of the present invention is used to push an electret speaker to emit sound, wherein the diaphragm used in the electret speaker is an electret material, which can be electrodeized and can maintain polarization for a long time after polarization. Dielectric material. Recently, it has been gradually taken into account and used in various products, such as high-voltage power supplies, transducers, microphones, and electrometers. Because the electret material uses the nanopore to increase the internal surface area of the polymer material, the charge density of the long-term storage can be improved, and the polymer diaphragm which can be used for the resident electricity can be applied to the speaker to make the sound system light and thin, and Because of its flexible characteristics, the design of the product will be more unconstrained and more portable, and it has the advantages of high efficiency, high frequency width and low distortion, so it has potential application potential for portable products. However, when the electret material is applied to the acoustic system, the problem of capacitive reactance matching is still the key point to be overcome. It must be properly designed to make the electret amplifier efficient, high-frequency wide and low-distortion amplification output to push the station. The polar speaker allows the user to listen to the original sound from the audio signal for maximum power transfer.

Based on the current inconvenience of the portable acoustic amplifier, it is necessary to provide a high-voltage DC power supply, only for a fixed placement, and a large power consumption, which makes the electrostatic acoustic amplifier unfavorable for carrying, and thus the present invention Combine the audio source, the audio amplifier circuit and the electret speaker that provide the audio signal, and use the front, middle and rear stage amplifying circuits to grade the audio signal to reduce the current to less than 10 mA, thereby greatly reducing the transmission loss of the audio signal. Noise interference. And the input impedance of the preamplifier circuit and the output impedance of the audio source providing the audio signal, the output impedance of the preamplifier circuit and the input impedance of the intermediate amplifier circuit, the output impedance of the intermediate amplifier circuit, and the input impedance of the post amplifier circuit and The output impedance of the post-amplifier circuit can be matched with the load capacitance of the electret speaker, so that the input of the preamplifier circuit can obtain the maximum power from the audio signal, and the output of the post-amplifier circuit can also transmit the maximum output power. For the electret speaker, the electret amplifier can improve the boosting efficiency, maintain the audio signal bandwidth and reduce the distortion of the audio signal amplification output, coupled with the thin and flexible characteristics of the electret speaker, can greatly improve the carrying Sexual inconvenience, providing users with more convenient leisure options.

The present invention provides an electret amplifier comprising: an audio source; an audio amplifier circuit having an output and an input coupled to the audio source, the audio amplifier circuit comprising a preamplifier circuit and a The intermediate amplifier circuit, the audio amplifier circuit receives a first audio signal and a first voltage level by the input terminal, wherein the preamplifier circuit boosts the first voltage level to a second voltage level Feeding to the intermediate amplifier circuit, thereby converting the first audio signal into one of the second audio signals, and the intermediate amplifier circuit boosts the second voltage level to a third voltage level, thereby The second audio signal is converted into a third audio signal; and an electret speaker coupled to the output end of the audio amplifying circuit to receive the third audio signal, and outputting the third audio signal corresponding to the audio signal A voice.

In the above electret amplifier of the present invention, the audio amplifying circuit further includes a post-amplifying circuit that receives and boosts the third voltage level from the intermediate amplifying circuit, thereby converting the third audio signal into A fourth audio signal is amplified, and wherein the electret speaker receives the fourth audio signal and outputs a sound corresponding thereto.

By the configuration of the electret amplifier described above, the audio source, the audio amplifying circuit and the electret speaker providing the audio signal can be successfully integrated into one body, and the characteristics of low distortion, high frequency width, low power consumption and portability are achieved. Among them, a power supply component can also be integrated into the electret amplifier to make it more convenient for life applications. In addition, the audio source of the audio signal can be replaced by an external method, and the sound can be converted into an audio signal input to the electret amplifier by the microphone.

While the invention has been described with reference to the preferred embodiments of the present invention, it is understood that those skilled in the art can modify the invention described herein while achieving the effect of the invention. Therefore, it is to be understood that the following description is a broad disclosure of those skilled in the art and is not intended to limit the invention.

Please refer to the first figure, which is a circuit block diagram of an electret amplifier 100 according to an embodiment of the invention, comprising an audio source 110, an audio amplifier circuit 120, and an electret speaker 130; wherein the audio source 110 A first audio signal 21 is provided to the audio amplifying circuit 120. The audio amplifying circuit 120 includes a preamplifier circuit 121, a mid amplifying circuit 122, and a post amplifying circuit 123.

In the above embodiment of the present invention, the audio amplifying circuit 120 has an output end and an input end coupled to the audio source 110, and receives a first audio signal 21 and a first voltage level through the input end. 11. The preamplifier circuit 121 boosts the first voltage level 11 to a second voltage level 12 and feeds it to the intermediate amplifier circuit 122, thereby converting the first audio signal 21 into a second audio. The signal 22 is further boosted by the intermediate amplifier circuit 122 to a third voltage level 13 to convert the second audio signal 22 into a third audio signal 23 for amplification. The third stage voltage level 13 is received and boosted by the post stage amplifying circuit 123 from the intermediate stage amplifying circuit 122, thereby converting the third audio signal 23 into an amplified fourth audio signal 24, and the electret speaker 130 The input end is coupled to the output end of the audio amplifying circuit 120. After receiving the amplified fourth audio signal 24, the audio output is generated corresponding to the fourth audio signal 24.

In the above embodiment of the present invention, the audio source 110 can input an audio signal to the electret amplifier 100 in an external manner, or convert the sound into an audio signal through the external connection of the microphone device. Electret amplifier 100. More preferably, the electret amplifier 100 includes a power supply component for providing the power required by the electret amplifier 100, wherein the voltage supplied by the power supply component is between 1V and 20V, preferably The power supply component is a battery module or a direct current power source, and the first voltage level 11 outputted through the audio source 110 is between 0V and 1V, wherein the amplification factor of the preamplifier circuit 121 is Between 1 and 10 times, the amplification factor of the intermediate amplification circuit 122 is between 1 and 20 times, and the amplification factor of the subsequent amplification circuit 123 is between 5 and 50 times. Preferably, the electret amplifier 100 includes an energy storage module coupled to the power supply component for storing power of the power supply component, such as a USB charging circuit.

In the above embodiment of the present invention, the audio source 110 further includes a capacity storage module for storing at least one audio signal. More preferably, the electret amplifier includes a switch control circuit, and the switch control circuit is coupled to the audio source 110 to control the audio source 110 to turn on and off the supply of the first audio signal 21.

Preferably, the preamplifier circuit 121 is an audio power amplifier for amplifying the first audio signal 21 and converting it into an amplified second audio signal 22. Preferably, The intermediate amplifier circuit 122 is an audio power amplifier for amplifying the second audio signal 22 and converting it into an amplified third audio signal 23. More preferably, the preamplifier circuit 121 and the intermediate amplifier circuit 122 can also function as a class A audio power amplifier, a class B audio power amplifier, a class C audio power amplifier, a class D audio power amplifier, a class AB audio power amplifier or An operational amplifier that operates from a power range of 0.01 W to 20 W allows the electret speaker 130 to produce a corresponding sound output.

In the above embodiment of the present invention, the post-amplifier circuit 123 is preferably a step-up transformer for adjusting the third voltage level 13 and boosting the input to the electret speaker 130.

In the present invention, the primary side inductance value of the step-up transformer ranges from 0.1 mH to 1 H, the number of coil turns is 10 匝 to 800 匝, and the secondary side inductance value ranges from 1H to 200H, and the coil ring The number is 800匝 to 8000匝, and the inductance and the turns ratio of the primary side and the secondary side are adjusted according to the magnification. In the present invention, the primary side capacitive reactance range of the step-up transformer is between 1 Ω and 100 Ω, the enamelled wire diameter is 0.02 ψ to 0.15 ψ, and the secondary side capacitive reactance range is between 500 Ω and 5000 Ω, and the enameled wire diameter value is It is 0.01ψ to 0.09ψ, and the impedance of the primary side and the secondary side and the ratio of the enamelled wire diameter are adjusted according to the magnification.

Referring to FIG. 2, a circuit block diagram of an electret amplifier 200 according to another embodiment of the present invention includes an audio source 110, an audio amplifier circuit 220, and an electret speaker 130; wherein the audio source The first audio signal 21 is provided to the audio amplifying circuit 220. The audio amplifying circuit 220 includes a preamplifier circuit 221 and a post amplifying circuit 223.

In the above embodiment of the present invention, the audio amplifying circuit 220 has an output end and an input end coupled to the audio source 110, and receives a first audio signal 21 and a first voltage level through the input end. 11. The preamplifier circuit 221 boosts the first voltage level 11 to a second voltage level 12 and feeds the second voltage level 12 to the subsequent stage amplifying circuit 223, thereby converting the first audio signal 21 into a second one of the amplification. The audio signal 22 is further boosted by the rear stage amplifying circuit 223 to a third voltage level 13 to convert the second audio signal 22 into a third audio signal 23. The input end of the electret speaker 130 is coupled to the output end of the audio amplifying circuit 220. After receiving the amplified third audio signal 23, the third audio signal 23 is generated in response to the third audio signal 23 to generate a sound output corresponding thereto. The preamplifier circuit 221 is an audio power amplifier for amplifying the first audio signal 21 and converting it into an amplified second audio signal 22. The post amplifying circuit 223 is a step-up transformer for adjusting the The second voltage level is 12, liter And then input to the electret speaker 130.

In the above embodiment of the present invention, preferably, the amplification factor of the preamplifier circuit 221 is between 1 and 200 times, and the amplification factor of the post amplifier circuit 223 is between 5 and 50 times.

In the above embodiment of the present invention, the preamplifier circuit 221 can function as a class A audio power amplifier, a class B audio power amplifier, a class C audio power amplifier, a class D audio power amplifier, a class AB audio power amplifier or an operational amplifier. It operates at a power range of 0.01 W to 20 W, allowing the electret speaker 130 to produce a corresponding sound output.

In the above embodiment of the present invention, preferably, the post-stage amplifying circuit 223 can function as a step-up transformer, and the primary side inductance value of the step-up transformer ranges from 0.1 mH to 1 H, and the number of coil turns is 10.匝 to 800匝, and the secondary side inductance value range is between 1H and 200H, the number of coil turns is 800匝 to 8000匝, and the inductance and the turns ratio of the primary side and the secondary side are adjusted according to the magnification. In the present invention, the primary side capacitive reactance range of the step-up transformer is between 1 Ω and 100 Ω, the enamelled wire diameter is 0.02 ψ to 0.15 ψ, and the secondary side capacitive reactance range is between 500 Ω and 5000 Ω, and the enameled wire diameter value is It is 0.01ψ to 0.09ψ, and the impedance of the primary side and the secondary side and the ratio of the enamelled wire diameter are adjusted according to the magnification.

Please refer to the third figure, which is a schematic circuit diagram of the audio amplifying circuit 120 according to the first embodiment of the above embodiment, wherein AMP1 is a preamplifier circuit 121, AMP2 and AMP3 are intermediate amplifying circuits 122, and AMP4 and AMP5 are postamplifiers. The circuit 123 first amplifies the first audio signal 21 and the first voltage level 11 by a certain multiple through the preamplifier circuit 121, and then divides the output end of the preamplifier circuit 121 into a two-pass channel signal through the circuit configuration. The AMP2 and the AMP3 of the intermediate amplifier circuit 122 convert the second audio signal 22 and the second voltage level 12 into the third audio signal 23 and the third voltage level 13 at an appropriate amplification factor, and finally pass through the rear stage amplifying circuit 123. AMP4 and AMP5 amplify the third audio signal 23 and the third voltage level 13 by an appropriate multiple, and convert it into a fourth audio signal 24 for providing to the electret speaker 130, wherein the fourth audio signal 24 of the AMP4 is provided to the right. The ear passes the channel, and the fourth audio signal 24 of the AMP5 is provided to the left ear channel, and the audio signal and the voltage level are sequentially amplified by the three-stage amplifier, and the input resistance of the preamplifier circuit 121 is blocked by the circuit configuration. The impedance of the audio source 110, the output impedance of the post-amplifier circuit 123, and the capacitive reactance of the electret speaker 130 can be matched. It should be noted that the circuit diagram of the audio amplifier circuit is merely exemplary and is not intended to limit the present invention. The circuit configuration of the audio amplifying circuit is well known to those skilled in the art, and the same circuit wiring can complete the audio amplifying circuit of the present invention, which is also the protection scope of the present invention.

The invention can successfully integrate the audio source, the audio amplifying circuit and the electret speaker which provide the audio signal into one body, and achieve the characteristics of low distortion, high frequency width, low power consumption and portability, and even a power supply component and Other control circuits are integrated into the electret amplifier to make it easier to use in life, suitable for portable products or outdoor products, and have potential applications.

Therefore, the present invention is a novel, progressive and industrially practical invention, and has profound development value. The present invention has been modified by those skilled in the art and is intended to be modified as described in the appended claims.

11. . . First voltage level

12. . . Second voltage level

13. . . Third voltage level

twenty one. . . First audio signal

twenty two. . . Second audio signal

twenty three. . . Third audio signal

twenty four. . . Fourth audio signal

100. . . Electret amplifier

110. . . Audio source

120. . . Audio amplifier circuit

121. . . Preamplifier circuit

122. . . Intermediate amplifier circuit

123. . . Post amplifier circuit

130. . . Electret speaker

200. . . Electret amplifier

220. . . Audio amplifier circuit

221. . . Preamplifier circuit

223. . . Post amplifier circuit

The first figure is a block diagram of an electret amplifier circuit in accordance with an embodiment of the present invention.

The second figure is a block diagram of an electret amplifier circuit in accordance with another embodiment of the present invention.

The third figure is a schematic circuit diagram of the audio amplifying circuit according to the first figure.

11. . . First voltage level

12. . . Second voltage level

13. . . Third voltage level

twenty one. . . First audio signal

twenty two. . . Second audio signal

twenty three. . . Third audio signal

twenty four. . . Fourth audio signal

100. . . Electret amplifier

110. . . Audio source

120. . . Audio amplifier circuit

121. . . Preamplifier circuit

122. . . Intermediate amplifier circuit

123. . . Post amplifier circuit

130. . . Electret speaker

Claims (29)

An electret amplifier comprising: an audio source; an audio amplifier circuit having an output and an input coupled to the audio source, and comprising a preamplifier circuit and a mid-level amplifier circuit, the audio amplifier The circuit receives a first audio signal and a first voltage level by the input terminal, wherein the preamplifier circuit boosts the first voltage level to a second voltage level and feeds the intermediate voltage to the intermediate amplifier circuit. The first audio signal is converted into a second audio signal by amplification, and the intermediate amplifier circuit boosts the second voltage level to a third voltage level, thereby converting the second audio signal into an amplification a third audio signal; an electret speaker coupled to the output end of the audio amplifying circuit to receive the third audio signal, and outputting a sound corresponding to the third audio signal; and a switch control circuit And coupled to the audio source to control the audio source to turn on and off the supply of the first audio signal. The electret amplifier of claim 1 further includes a power supply component that provides a power to the electret amplifier. The electret amplifier of claim 2, wherein the power supply element provides a voltage between 1V and 20V. The electret amplifier of claim 2, wherein the power supply component is a battery module or a DC power source. The electret amplifier of claim 2, further comprising an energy storage module coupled to the power supply component. The electret amplifier of claim 1, wherein the first voltage level is between 0V and 1V. The electret amplifier of claim 1, wherein the preamplifier circuit has a magnification of between 1 and 10 times. The electret amplifier of claim 1, wherein the intermediate amplifier circuit has a magnification of between 1 and 20 times. The electret amplifier of claim 1, wherein the preamplifier circuit and the intermediate amplifier circuit are an audio power amplifier. The electret amplifier of claim 9, wherein the audio power amplifier is selected from the group consisting of a class A audio power amplifier, a class B audio power amplifier, a class C audio power amplifier, a class D audio power amplifier, and a One of the class AB audio power amplifiers and an operational amplifier. The electret amplifier of claim 9, wherein the power amplifier of the audio power amplifier is between 0.01 W and 20 W. The electret amplifier of claim 1, wherein the audio amplifier circuit further comprises a post-amplifier circuit that receives and boosts the third voltage level from the intermediate amplifier circuit, thereby using the third audio signal Converting to amplifying one of the fourth audio signals, and wherein the electret speaker receives the fourth audio signal and outputs a sound corresponding thereto. For example, in the electret amplifier of claim 12, the amplification factor of the post-amplifier circuit is between 5 and 50 times. The electret amplifier of claim 12, wherein the post-amplifier circuit is a step-up transformer for adjusting the third voltage level. For example, in the electret amplifier of claim 14, wherein the step-up transformer has a primary side inductance value ranging from 0.1 mH to 1 H, and the number of coil turns is 10 匝 to 800 匝. For example, in the electret amplifier of claim 14, wherein the step-up transformer has a secondary side inductance value ranging from 1H to 200H, and the number of coil turns is 800 匝 to 8000 匝. For example, in the electret amplifier of claim 14, wherein the step-up transformer has a primary side impedance ranging from 1 Ω to 100 Ω and an enameled wire diameter of 0.02 ψ to 0.15 ψ. For example, in the electret amplifier of claim 14, wherein the step-up transformer has a secondary side impedance ranging from 500 Ω to 5000 Ω, and an enameled wire diameter of 0.01 ψ to 0.09 ψ. The electret amplifier of claim 1, wherein the audio source comprises a capacity storage module for storing at least one audio signal. For example, in the electret amplifier of claim 1, wherein the audio source is externally connected to the electret amplifier, or the external sound is converted into an audio signal input to the resident via the microphone device. Polar body amplifier. An electret amplifier comprising: an audio source; an audio amplifier circuit having an output and an input coupled to the audio source, and comprising a preamplifier circuit and a post amplifier circuit, the audio The amplifier circuit receives a first audio signal and a first voltage level by the input terminal, wherein the preamplifier circuit boosts the first voltage level to a second voltage level and feeds the second voltage level to the second stage a circuit, wherein the first audio signal is converted into a second audio signal, and the second-stage amplifying circuit boosts the second voltage level to a third voltage level, thereby converting the second audio signal Amplifying a third audio signal; and an electret speaker coupled to the output end of the audio amplifying circuit to receive the third audio signal, and outputting a sound corresponding to the third audio signal; The preamplifier circuit is an audio power amplifier, and the post amplifier circuit is a step-up transformer for adjusting the second voltage level. For example, in the electret amplifier of claim 21, the amplification factor of the preamplifier circuit is between 1 and 200 times. For example, in the electret amplifier of claim 21, the amplification factor of the post-amplifier circuit is between 5 and 50 times. The electret amplifier of claim 21, wherein the audio power amplifier is selected from the group consisting of a class A audio power amplifier, a class B audio power amplifier, a class C audio power amplifier, a class D audio power amplifier, and a One of the class AB audio power amplifiers and an operational amplifier. The electret amplifier of claim 21, wherein the power amplifier of the audio power amplifier is between 0.01 W and 20 W. For example, in the electret amplifier of claim 21, the primary side inductance value of the step-up transformer is between 0.1 mH and 1H, and the number of coil turns is 10 匝 to 800 匝. For example, in the electret amplifier of claim 21, the secondary side inductance value of the step-up transformer is between 1H and 200H, and the number of coil turns is 800匝 to 8000匝. For example, the electret amplifier of claim 21, wherein the step-up transformer has a primary side impedance ranging from 1 Ω to 100 Ω, and an enameled wire diameter of 0.02 ψ to 0.15 ψ. For example, in the electret amplifier of claim 21, the secondary side impedance range of the step-up transformer is between 500 Ω and 5000 Ω, and the enameled wire diameter is 0.01 ψ to 0.09 ψ.