CN106911980A - Earphone circuit with adjustable feedback type active noise reduction level - Google Patents

Abstract

The invention relates to an earphone circuit with adjustable feedback type active noise reduction level, which comprises: a noise input part, an audio input part and an amplification output part; the noise input part and the audio input part are mixed through an adder, and then signals are amplified through an amplification output part and then output; the amplifying output part returns the output audio signal to the noise output part to form adjustable feedback type active noise reduction. The invention solves the problem that the adjustable feedback type active noise reduction level, the active noise reduction level and the music equalizer in the prior art all use one gain control by arranging the adjustable amplifier, and the audio signal gain is not influenced by the feedback type active noise reduction level.

Description

Headphone circuit with adjustable feedback ANC level

technical field

The invention relates to the technical field of earphone circuits, in particular to an earphone circuit with adjustable feedback active noise reduction level.

Background technique

In the prior art, the feedback ANC level, ANC level and music equalizer adjustment of the earphone all use the same headphone gain. The disadvantage of the prior art is that the music frequency gain is affected by the feedback ANC level. The influence of the earphone has a great influence on the sound quality of the earphone.

Therefore, the prior art needs to be improved.

Contents of the invention

The invention discloses an earphone circuit with an adjustable feedback active noise reduction level, which is used to realize the adjustable feedback active noise reduction level of the earphone, the active noise reduction level and the music equalizer adjustment all use a gain control, And the audio signal gain is not affected by the feedback active noise reduction level.

An embodiment of the present invention provides an earphone circuit with adjustable feedback active noise reduction level, including:

Noise input part, audio input part, amplified output part;

After the noise input part and the audio input part are mixed by an adder, the signal is amplified by the amplifying output part, and then the signal is output;

The noise input part includes a microphone and a first filter. The microphone receives a mixed signal of natural noise and the sound returned by the speaker, and amplifies the mixed signal to form a feedback active noise reduction noise signal. The noise signal is filtered by the first filter. filter for noise;

The audio input part includes an audio source and a second filter. After the audio signal of the audio source is amplified, it is output to the second filter. The second filter filters the audio signal and outputs the filtered audio signal;

The amplified output part includes: an adjustable amplifier, a second adder, an amplifier, and a loudspeaker, the noise signal of the noise input part is mixed with the audio signal of the audio input part, and output to the adjustable amplifier, and the adjustable amplifier pairs the mixed signal Perform adjustable amplification, then mix with the audio signal of the audio source through the second adder, output to the amplifier for amplification, and then output to the speaker.

In another embodiment of the headphone circuit with adjustable feedback active noise reduction level based on the above-mentioned present invention, the product of the gain of the loudspeaker, the first filter, the amplifier and the microphone is A, and the gain of the second filter is is B, the gain of the adjustable amplifier is g, then:

The noise gain of the system is:

The audio gain of the system is: 1+B×g;

The overall gain of the headphone circuit is:

In another embodiment of the headphone circuit with adjustable feedback active noise reduction level based on the above-mentioned present invention, the product of the gain of the loudspeaker, the first filter, the amplifier and the microphone is A, and the gain of the second filter is If B satisfies A≈B, then:

In another embodiment of the headphone circuit with adjustable feedback active noise reduction level based on the present invention, the audio input part further includes a second adjustable amplifier;

After the audio signal of the audio source is output to the second adjustable amplifier for adjustable amplification, the amplified audio signal is input to the second filter;

Set the gain of the first adjustable amplifier as g1, the gain of the second adjustable amplifier as g2, the product of the gain of the loudspeaker, the first filter, the amplifier and the microphone is A, and the gain of the second filter is B, then:

The noise gain of the system is:

The audio gain of the system is: 1+B×g2×g1;

The overall gain of the headphone circuit is:

Let B×g2×g1≈A×g1, then:

Compared with the prior art, the present invention includes the following advantages:

The headphone circuit with adjustable feedback active noise reduction level of the present invention can adjust the adjustable feedback active noise reduction level, active noise reduction level and music equalizer existing in the prior art by setting an adjustable amplifier. The problem of using one gain control is solved, and the audio signal gain is not affected by the feedback active noise reduction level. The invention has a simple structure, is convenient to use, and has an obvious effect of improving the sound quality of the earphone.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the drawings used in the description of the embodiments or the prior art.

Fig. 1 is a circuit diagram of an embodiment of an earphone circuit with adjustable feedback active noise reduction level of the present invention.

Fig. 2 is a waveform diagram of the noise reduction gain of the headphone circuit with adjustable feedback active noise reduction level as the adjustable amplifier varies.

Fig. 3 is a waveform diagram of the audio gain of the headphone circuit with adjustable feedback active noise reduction level as the adjustable amplifier varies.

Fig. 4 is a waveform diagram of the total gain of the headphone circuit with adjustable feedback active noise reduction level when the adjustable amplifier changes.

Fig. 5 is a circuit diagram of another embodiment of the headphone circuit with adjustable feedback active noise reduction level of the present invention.

In the figure: 1 noise input part, 2 audio input part, 3 amplified output part

detailed description

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Fig. 1 is a circuit diagram of an embodiment of the earphone circuit with adjustable feedback active noise reduction level of the present invention, as shown in Fig. 1, the earphone circuit with adjustable feedback active noise reduction level includes:

Noise input part 1, audio input part 2, amplification output part 3;

After the noise input part 1 and the audio input part 2 are mixed by an adder, the signal is amplified by the amplification output part 3, and then the signal is output;

The noise input part 1 includes a microphone and a first filter. The microphone receives a mixed signal of natural noise and the sound returned by the speaker, and amplifies the mixed signal to form a feedback-type active noise reduction noise signal. The noise signal passes through the first filter for noise filtering;

The audio input part 2 includes an audio source and a second filter. After the audio signal of the audio source is amplified, it is output to the second filter. The second filter filters the audio signal and outputs the filtered audio signal;

The amplified output part 3 includes: an adjustable amplifier, a second adder, an amplifier, a loudspeaker, and the noise signal of the noise input part 1 and the audio signal of the audio input part 2 are mixed and output to the adjustable amplifier, and the adjustable amplifier Adjustable amplification is performed on the mixed signal, then mixed with the audio signal of the audio source through the second adder, output to the amplifier for amplification, and then output to the speaker.

In a specific embodiment, the microphone of the earphone is placed in front of the speaker, and the microphone receives the noise in nature and the feedback sound of the speaker, and the mixed sound is amplified through the amplifier provided by the microphone. Since the microphone receives the feedback sound of the speaker, therefore, The noise part in the mixed noise is suppressed, and a feedback active noise reduction is formed. Since an adjustable amplifier is set in the amplifying output part, an adjustable feedback active noise reduction is formed in the noise input part.

Set the product of the gain of loudspeaker, first filter, amplifier, microphone as the open loop gain A of feedback system, the gain of the second filter is B, the gain of adjustable amplifier is g, because the prior art has adjustable feedback The headphone circuit of the active noise reduction level does not have an adjustable amplifier. It places the microphone in the front room of the headphone and forms a feedback system next to the speaker. While the gain of the feedback active noise reduction system changes the noise and noise in the front room of the headphone Audio, therefore, the noise gain of the prior art headphone circuit with adjustable feedback ANC level is:

The larger the value of A, the greater the attenuation of the headphone circuit. In order to keep the speaker with the original total gain of the headphone circuit and the gain of the audio equalizer, the input compensation EQ is designed as:

EQ≈1+A (2)

Therefore, the overall gain of the headphone circuit is:

However, since changing the open-loop gain A of the feedback system needs to redesign the input compensation gain EQ, and the open-loop gain A and the input compensation gain EQ of the feedback system of the prior art are fixed, in the embodiments of the present invention, Since the adjustable amplifier is set, therefore,

The noise gain of the system is:

The audio gain of the system is: 1+B×g (5)

The overall gain of the headphone circuit is:

Set the product of the gain of the speaker, the first filter, the amplifier, and the microphone as the open-loop gain A of the feedback system, and the gain of the second filter is B to satisfy A≈B, then:

As a result, only the speaker can get close to the original audio gain, and less affected by the adjustable amplifier gain g or ANC level changes.

Fig. 2 is the noise reduction gain waveform diagram when the headphone circuit with adjustable feedback active noise reduction level of the present invention changes with the adjustable amplifier, as shown in Fig. 2, by adjusting the variable resistance of the adjustable amplifier, when When the variable resistors are set to three grades of high, medium and low, the active noise reduction gain will change with the frequency of the noise signal, and the noise gain will decrease with the increase of the adjustable resistance of the adjustable amplifier. .

Fig. 3 is the audio gain waveform diagram when the headphone circuit with adjustable feedback active noise reduction level of the present invention changes with the adjustable amplifier, as shown in Fig. 3, by adjusting the variable resistance of the adjustable amplifier, when the When the rheostats are set to high, medium and low levels, the gain of the audio signal will change as the frequency of the audio signal changes. Combining with Figure 2, it can be seen that when the gain of the audio signal becomes larger, the gain of the noise signal decreases. When the gain is 0-1KHz, the change range of the gain is relatively large, and the gain of the audio signal decreases with the adjustable resistance of the adjustable amplifier. and decreases, the gain of the noise signal increases as the adjustable resistance of the adjustable amplifier decreases.

Fig. 4 is the total gain waveform diagram of the headphone circuit with adjustable feedback active noise reduction level of the present invention when it changes with the adjustable amplifier. As shown in Fig. 4, by adjusting the variable resistance of the adjustable amplifier, when When the variable resistors are set to three grades of high, medium and low, the overall gain of the system will change with the change of the frequency of the mixed signal. Obviously, the gain values are relatively consistent.

Fig. 5 is a circuit diagram of another embodiment of the headphone circuit with adjustable feedback active noise reduction level of the present invention, as shown in Fig. 5, the audio input part 2 also includes a second adjustable amplifier;

After the audio signal of the audio source is output to the second adjustable amplifier for adjustable amplification, the amplified audio signal is input to the second filter;

Set the gain of the first adjustable amplifier as g1, the gain of the second adjustable amplifier as g2, the product of the gain of the loudspeaker, the first filter, the amplifier and the microphone is A, and the gain of the second filter is B, then:

The noise gain of the system is:

The audio gain of the system is: 1+B×g2×g1 (9)

The overall gain of the headphone circuit is:

Let B×g2×g1≈A×g1, then:

The headphone circuit with adjustable feedback active noise reduction level provided by the present invention has been introduced in detail above. In this paper, specific examples are used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only It is used to help understand the method of the present invention and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and scope of application. In summary, this The content of the description should not be construed as limiting the present invention.

Finally, it should be noted that: the above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it still The technical solutions recorded in the foregoing embodiments may be modified, or some of the technical features may be replaced equivalently, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the within the protection scope of the present invention.

Claims (4)

1. A headphone circuit with adjustable feedback active noise reduction level, characterized in that, comprising: Noise input part, audio input part, amplified output part; After the noise input part and the audio input part are mixed by an adder, the signal is amplified by the amplifying output part, and then the signal is output; The noise input part includes a microphone and a first filter. The microphone receives a mixed signal of natural noise and the sound returned by the speaker, and amplifies the mixed signal to form a feedback active noise reduction noise signal. The noise signal is filtered by the first filter. filter for noise; The audio input part includes an audio source and a second filter. After the audio signal of the audio source is amplified, it is output to the second filter. The second filter filters the audio signal and outputs the filtered audio signal; The amplified output part includes: an adjustable amplifier, a second adder, an amplifier, and a loudspeaker, the noise signal of the noise input part is mixed with the audio signal of the audio input part, and output to the adjustable amplifier, and the adjustable amplifier pairs the mixed signal Perform adjustable amplification, then mix with the audio signal of the audio source through the second adder, output to the amplifier for amplification, and then output to the speaker. 2. earphone circuit according to claim 1, is characterized in that, the product of the gain of described loudspeaker, first filter, amplifier, microphone is A, the gain of the second filter is B, and the gain of adjustable amplifier is g, then: The noise gain of the system is: The audio gain of the system is: 1+B×g; The overall gain of the headphone circuit is: 3. The earphone circuit according to claim 2, wherein the product of the gain of the loudspeaker, the first filter, the amplifier, and the microphone is A, and the gain of the second filter is B to satisfy A≈B, then: $\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; g</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; \&ap;</span>\mathrm{<span\; class="notranslate">\; 1.</span>}$ 4. The earphone circuit according to claim 1 or 2, wherein the audio input part also includes a second adjustable amplifier; After the audio signal of the audio source is output to the second adjustable amplifier for adjustable amplification, the amplified audio signal is input to the second filter; Set the gain of the first adjustable amplifier as g1, the gain of the second adjustable amplifier as g2, the product of the gain of the loudspeaker, the first filter, the amplifier and the microphone is A, and the gain of the second filter is B, then: The noise gain of the system is: The audio gain of the system is: 1+B×g2×g1; The overall gain of the headphone circuit is: Let B×g2×g1≈A×g1, then: $\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; g</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; g</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; g</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&ap;</span>\mathrm{<span\; class="notranslate">\; 1.</span>}$