An earphone noise reduction circuit and an earphone device

Abstract

The present invention relates to a headphone noise reduction circuit and a headphone device. The circuit includes a feedback noise reduction circuit, a feedforward noise reduction circuit, a noise reduction self-starting circuit, and a first controller. The noise reduction self-starting circuit is used to determine whether to start the noise reduction function according to the feedback noise signal and the feedforward noise signal. Therefore, the headphone noise reduction circuit can realize the noise reduction self-starting function only through the circuit, and also uses two types of noise signals as the basis for starting the noise reduction function, which can start the noise reduction function more precisely, and then can reduce noise in time. At the same time, when the noise reduction self-starting circuit determines to start the noise reduction function, the first controller is used to control the working states of the feedback noise reduction circuit and the feedforward noise reduction circuit respectively according to the feedback noise signal and the feedforward noise signal, so that the feedback noise reduction circuit and the feedforward noise reduction circuit respectively reduce the noise of their respective noise signals, further improving the noise reduction function and effectively improving the user experience.

Description

Technical Field

[0001] The present invention relates to the field of headphone noise reduction, and particularly to a headphone noise reduction circuit and a headphone device. Background Art

[0002] With the progress of technology and the improvement of people's modern life needs, Bluetooth TWS (True Wireless Stereo) headphones are widely loved by people because they get rid of the connecting wire from the player to the headphone body. Bluetooth headphones are especially suitable for wearing during sports or other activities, which can reduce the trouble caused by wire entanglement and are very convenient.

[0003] Current Bluetooth TWS headphones generally have a noise reduction function and a noise reduction self-start function. However, the traditional noise reduction self-start circuit only analyzes the external environmental noise collected by the headphone feedforward microphone to determine whether to automatically turn on the noise reduction function. However, due to the slight differences in the ear structures of different people and different headphone wearing postures, when wearing the same headphones, the internal ear noise of different users may be inconsistent. Judging whether to automatically start the noise reduction function only through the feedforward microphone has the defect of insufficient accuracy, which will further lead to untimely noise reduction and poor noise reduction effect. Summary of the Invention

[0004] The embodiments of the present invention at least solve one of the above technical problems to some extent. Therefore, the present invention provides a headphone noise reduction circuit and a headphone device, which can start the noise reduction function more accurately, have a better noise reduction effect, and improve the user experience.

[0005] In a first aspect, an embodiment of the present invention provides a headphone noise reduction circuit applied to a headphone device, including: a feedback noise reduction circuit, a feedforward noise reduction circuit, a noise reduction self-start circuit, and a first controller;

[0006] The feedback noise reduction circuit is electrically connected to the noise reduction self-start circuit, a speaker, and the first controller respectively. The feedback noise reduction circuit is used to obtain a feedback noise signal and perform noise reduction on the feedback noise signal;

[0007] The feedforward noise reduction circuit is electrically connected to the noise reduction self-start circuit, the speaker, and the first controller respectively. The feedforward noise reduction circuit is used to obtain a feedforward noise signal and perform noise reduction on the feedforward noise signal;

[0008] The noise reduction self-start circuit is also electrically connected to the first controller, and is used to determine whether to start the noise reduction function according to the feedback noise signal and the feedforward noise signal; and

[0009] When the noise reduction self - start circuit determines to start the noise reduction function, the first controller is used to control the working states of the feedback noise reduction circuit and the feed - forward noise reduction circuit according to the feedback noise signal and the feed - forward noise signal respectively.

[0010] The noise reduction self - start circuit includes: a feedback comparison circuit, a feed - forward comparison circuit, an OR gate circuit, and a second controller;

[0011] The feedback comparison circuit is electrically connected to the feedback noise reduction circuit and the first input terminal of the OR gate circuit respectively. The feedback comparison circuit is used to obtain the feedback noise signal and compare the feedback noise signal with a first reference value to obtain a first comparison result;

[0012] The feed - forward comparison circuit is electrically connected to the feed - forward noise reduction circuit and the second input terminal of the OR gate circuit respectively. The feed - forward comparison circuit is used to obtain the feed - forward noise signal, compare the feed - forward noise signal with a second reference value to obtain a second comparison result;

[0013] The output terminal of the OR gate circuit is also electrically connected to the second controller. The OR gate circuit is used to perform a logical OR operation on the first comparison result and the second comparison result to obtain a logical value; and

[0014] The second controller is also electrically connected to the first controller. The second controller is used to determine whether to send a noise reduction start signal to the first controller according to the logical value.

[0015] In some embodiments, the feedback comparison circuit includes a feedback comparator. The non - inverting input terminal of the feedback comparator is electrically connected to the feedback noise reduction circuit for obtaining the feedback noise signal;

[0016] The inverting input terminal of the feedback comparator is used to obtain the first reference value;

[0017] The output terminal of the feedback comparator is electrically connected to the first input terminal of the OR gate circuit.

[0018] In some embodiments, the feed - forward comparison circuit includes a feed - forward comparator. The non - inverting input terminal of the feed - forward comparator is electrically connected to the feed - forward noise reduction circuit for obtaining the feed - forward noise signal;

[0019] The inverting input terminal of the feed - forward comparator is used to obtain the second reference value;

[0020] The output terminal of the feed - forward comparator is electrically connected to the second input terminal of the OR gate circuit.

[0021] In some embodiments, the second controller is further used for:

[0022] If the logical value is true, it is determined to activate the noise reduction function;

[0023] If the logical value is false, it is determined not to activate the noise reduction function.

[0024] In some embodiments, the feedback noise reduction circuit includes a feedback microphone, a feedback filter, and a first switch;

[0025] The feedback microphone is electrically connected to the feedback filter and the feedback comparison circuit respectively, and the feedback microphone is used to collect the feedback noise signal;

[0026] One end of the feedback filter is electrically connected to the first switch, and the other end is electrically connected to the feedback microphone and the feedback comparison circuit respectively. The feedback filter is used to filter and invert the feedback noise signal to obtain a feedback noise reduction signal;

[0027] The first end of the first switch is electrically connected to the feedback filter, the second end of the first switch is electrically connected to the speaker, and the control end of the first switch is electrically connected to the first controller. When the first switch is in the conducting working state, the feedback noise reduction signal is transmitted to the speaker, and the feedback noise reduction circuit is in the noise reduction working state.

[0028] In some embodiments, the first controller is further configured to: when receiving the noise reduction start signal, control the working state of the first switch according to the feedback noise signal and a first preset threshold.

[0029] In some embodiments, the feedforward noise reduction circuit includes a feedforward microphone, a feedforward filter, and a second switch;

[0030] The feedforward microphone is electrically connected to the feedforward filter and the feedforward comparison circuit respectively, and the feedforward microphone is used to collect the feedforward noise signal;

[0031] One end of the feedforward filter is electrically connected to the second switch, and the other end is electrically connected to the feedforward microphone and the feedforward comparison circuit respectively. The feedforward filter is used to filter and invert the feedforward noise signal to obtain a feedforward noise reduction signal;

[0032] The first end of the second switch is electrically connected to the feedforward filter, the second end of the second switch is electrically connected to the speaker, and the control end of the second switch is electrically connected to the first controller. When the second switch is in the conducting working state, the feedforward noise reduction signal is transmitted to the speaker, and the feedforward noise reduction circuit is in the noise reduction working state.

[0033] In some embodiments, the first controller is further configured to: when receiving the noise reduction start signal, control the working state of the second switch according to the feedforward noise signal and a second preset threshold.

[0034] In a second aspect, an embodiment of the present invention provides a headphone device, including:

[0035] a speaker for playing an audio signal; and

[0036] the headphone noise reduction circuit as described above, the headphone noise reduction circuit being electrically connected to the speaker for reducing noise of the audio signal.

[0037] Compared with the prior art, the present invention has at least the following beneficial effects: The headphone noise reduction circuit in the present invention is applied to a headphone device. The headphone noise reduction circuit includes a feedback noise reduction circuit, a feedforward noise reduction circuit, a noise reduction self-starting circuit, and a first controller. The feedback noise reduction circuit is electrically connected to the noise reduction self-starting circuit, the speaker, and the first controller respectively. The feedforward noise reduction circuit is electrically connected to the noise reduction self-starting circuit, the speaker, and the first controller respectively. The noise reduction self-starting circuit is also electrically connected to the first controller. The noise reduction self-starting circuit is configured to determine whether to start the noise reduction function according to the feedback noise signal and the feedforward noise signal. Therefore, the headphone noise reduction circuit can realize the noise reduction self-starting function only through the circuit, and also uses two types of noise signals as the basis for starting the noise reduction function. Compared with the circuit that uses a single noise signal as the basis for starting the noise reduction function, it can start the noise reduction function more accurately, and thus can reduce noise in a timely manner and improve the user experience. At the same time, when the noise reduction self-starting circuit determines to start the noise reduction function, the first controller is configured to control the working states of the feedback noise reduction circuit and the feedforward noise reduction circuit according to the feedback noise signal and the feedforward noise signal respectively, so that the feedback noise reduction circuit and the feedforward noise reduction circuit reduce noise of their respective noise signals respectively, further improving the noise reduction function and effectively improving the user experience. Description of the Drawings

[0038] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the drawings in the figures do not constitute a scale limitation.

[0039] Figure 1 is a schematic diagram of the in-ear noise of the same headphone of different users provided by an embodiment of the present invention;

[0040] Figure 2 is a schematic diagram of the circuit structure of a headphone noise reduction circuit provided by an embodiment of the present invention;

[0041] Figure 3It is a schematic circuit diagram of one of the headphone noise reduction circuits provided by an embodiment of the present invention;

[0042] Figure 4 It is a schematic circuit diagram of one of the headphone noise reduction circuits provided by an embodiment of the present invention. Detailed implementation manners

[0043] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the protection scope of the present invention.

[0044] It should be noted that if there is no conflict, the various features in the embodiments of the present invention can be combined with each other, and all are within the protection scope of the present invention. In addition, although the functional modules are divided in the device schematic diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order from the module division in the device or the flowchart. Furthermore, the terms "first", "second", "third", etc. used in the present invention do not limit the data and execution order, but only distinguish the same items or similar items with basically the same functions and effects.

[0045] Due to the slight differences in the ear structures of different people and the different headphone wearing postures, when users wear the same headphones, the in-ear noises of different users may not be the same. For example, Figure 1 As shown, two different users use the same headphone. Due to the aforementioned ear structure or wearing posture reasons, the in-ear noises of the two are not the same. The noise signal 1 is the in-ear noise of the first user, and the noise signal 2 is the in-ear noise of the second user. If only the magnitude of the external environmental noise is considered and the magnitude of the residual in-ear noise is ignored, there may be an inaccurate situation in the judgment of the self-start of the noise reduction function, thereby affecting the user experience of the headphone.

[0046] Therefore, an embodiment of the present invention provides a headphone noise reduction circuit 100, which is applied to a headphone device. Please refer to Figure 2, the noise reduction circuit 100 of the earphone includes a feedback noise reduction circuit 10, a feedforward noise reduction circuit 20, a noise reduction self-start circuit 30, and a first controller 40. The feedforward noise reduction circuit 20 is electrically connected to the noise reduction self-start circuit 30, the speaker 200, and the first controller 40 respectively. The feedforward noise reduction circuit 20 is used to obtain a feedforward noise signal and perform noise reduction on the feedforward noise signal. The feedforward noise reduction circuit 20 can set a feedforward microphone MIC2 outside the earphone to collect the external environmental noise signal of the ear, that is, the feedforward noise signal, and perform time-domain and frequency-domain processing on the feedforward noise signal to obtain a corresponding noise reduction signal, and then transmit the noise reduction signal to the speaker 200 in the earphone for playback, which cancels out the noise signal transmitted into the earphone through the earphone structure from the external environmental noise signal, achieving the purpose of reducing the external ear noise signal. Usually, the feedforward noise reduction circuit 20 cannot achieve complete noise reduction, and further deep noise reduction needs to be achieved through the feedback noise reduction circuit 10.

[0047] The feedback noise reduction circuit 10 is electrically connected to the noise reduction self-start circuit 30, the speaker 200, and the first controller 40 respectively. The feedback noise reduction circuit 10 is used to obtain a feedback noise signal and perform noise reduction on the feedback noise signal. The feedback noise reduction circuit 10 uses a microphone to collect the noise signal in the ear, that is, to collect the feedback noise signal. Only the microphone is set inside the earphone, and then perform time-domain and frequency-domain processing on the feedback noise signal to obtain a corresponding noise reduction signal. Similarly, transmit the noise reduction signal to the speaker 200 in the earphone for playback, which cancels out the noise in the ear, achieving the purpose of reducing the noise signal in the ear.

[0048] The noise reduction self-start circuit 30 is also electrically connected to the first controller 40, and is used to determine whether to start the noise reduction function according to the feedback noise signal and the feedforward noise signal. If any one of the feedback noise signal or the feedforward noise signal reaches the standard that needs noise reduction, the noise reduction self-start circuit 30 sends a first signal to the first controller 40, reflecting the determination to start the noise reduction function, so that the first controller 40 executes corresponding noise reduction measures according to the first signal; if neither the feedback noise signal nor the feedforward noise signal reaches the standard that needs noise reduction, the noise reduction self-start circuit 30 sends a second signal to the first controller 40, or does not send a signal, reflecting the determination not to turn on the noise reduction function, so that the first controller 40 analyzes that the current state is one that does not require noise reduction according to the second signal. Therefore, the noise reduction self-start circuit 30 can realize the noise reduction self-start function of the earphone device, and the noise reduction self-start circuit 30 uses the feedback noise signal and the feedforward noise signal as the common basis for whether to start the noise reduction function, not just using a single noise signal as the basis for starting the noise reduction function. It can improve the accuracy of noise reduction self-start, start the noise reduction function more precisely, and then enable the corresponding noise reduction circuit to reduce noise in time, improving the user experience.

[0049] Meanwhile, when the noise reduction self-start circuit 30 determines to activate the noise reduction function, the first controller 40 is used to control the operating states of the feedback noise reduction circuit 10 and the feedforward noise reduction circuit 20 according to the feedback noise signal and the feedforward noise signal respectively, so that the feedback noise reduction circuit 10 and the feedforward noise reduction circuit 20 reduce the noise of their respective noise signals. For example, when the first controller 40 receives the first signal sent by the noise reduction self-start circuit 30, it determines to activate the noise reduction function, and then judges whether the feedforward noise signal and the feedback noise signal reach the corresponding noise standards. If they reach the standards, it controls the corresponding noise reduction circuit to enter the noise reduction operating state to achieve the noise reduction function; when the first controller 40 receives the second signal sent by the noise reduction self-start circuit 30, or does not receive any signal sent by the noise reduction self-start circuit 30, it determines not to activate the noise reduction function, and then controls the feedforward noise reduction circuit 20 and the feedback noise reduction circuit 10 not to work. Therefore, when the noise reduction self-start circuit 30 determines to activate the noise reduction function, the first controller 40 then controls the corresponding noise reduction circuit to enter the noise reduction operating state, and reduces the two types of noise signals respectively, further improving the noise reduction function and effectively improving the user experience.

[0050] In summary, the noise reduction circuit of this headphone can realize the noise reduction self-start function only through the circuit, and also uses two types of noise signals as the basis for activating the noise reduction function. Compared with the circuit that uses a single noise signal as the basis for activating the noise reduction function, it can activate the noise reduction function more accurately, and thus can reduce noise in a timely manner and improve the user experience. Meanwhile, when the noise reduction self-start circuit determines to activate the noise reduction function, the first controller is used to control the operating states of the feedback noise reduction circuit and the feedforward noise reduction circuit according to the feedback noise signal and the feedforward noise signal respectively, so that the feedback noise reduction circuit and the feedforward noise reduction circuit reduce the noise of their respective noise signals respectively, further improving the noise reduction function and effectively improving the user experience.

[0051] In some embodiments, the first controller 40 can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a single-chip microcomputer, an ARM (Acorn RISC Machine), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of these components. Moreover, the first controller 40 can also be any conventional processor, controller, microcontroller, or state machine. The first controller 40 can also be implemented as a combination of computing devices. For example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP and / or any other such configuration.

[0052] Please refer to Figure 3 , Figure 3 which is a schematic circuit structure diagram of one of the headphone noise reduction circuits provided by the embodiments of the present invention. As Figure 3As shown in the figure, the noise reduction self-starting circuit 30 includes: a feedback comparison circuit 31, a feedforward comparison circuit 32, an OR gate circuit 33, and a second controller 34. Among them, the feedback comparison circuit 31 is electrically connected to the feedback noise reduction circuit 10 and the first input terminal of the OR gate circuit 33 respectively. The feedback comparison circuit 31 is used to obtain the feedback noise signal and compare the feedback noise signal with the first reference value to obtain the first comparison result. The specific value of the first reference value can be set by the user according to needs. Generally, it represents the standard for noise reduction of the feedback noise signal. The first comparison result includes two results, and these two results can be represented by logical values. For example, if the logical value is true, it is represented by logical 1, and if the logical value is false, it is represented by logical 0.

[0053] Compare the feedback noise signal with the first reference value. If the feedback noise signal is greater than or equal to the first reference value, the first comparison result obtained by the feedback comparison circuit 31 is logical 1; if the feedback noise signal is less than the first reference value, the first comparison result obtained by the feedback comparison circuit 31 is logical 0.

[0054] Similarly, the feedforward comparison circuit 32 is electrically connected to the feedforward noise reduction circuit 20 and the second input terminal of the OR gate circuit 33 respectively. The feedforward comparison circuit 32 is used to obtain the feedforward noise signal, compare the feedforward noise signal with the second reference value to obtain the second comparison result. The value of the second reference value can be set by the user according to needs. The working process and principle of the feedforward comparison circuit 32 are similar to those of the feedback comparison circuit 31. Compare the feedforward noise signal with the second reference value. If the feedforward noise signal is greater than or equal to the second reference value, the second comparison result obtained by the feedforward comparison circuit 32 is logical 1; if the feedforward noise signal is less than the second reference value, the second comparison result obtained by the feedforward comparison circuit 32 is logical 0.

[0055] The output terminal of the OR gate circuit 33 is also electrically connected to the second controller 34, and the second controller 34 is also electrically connected to the first controller 40. The OR gate circuit 33 is used to perform a logical OR operation based on the first comparison result and the second comparison result to obtain a logical value. The second controller 34 is used to determine whether to send a noise reduction start signal to the first controller 40 according to the logical value. If any one of the first comparison result and the second comparison result is true, the logical value obtained by the OR gate circuit 33 is true. If both the first comparison result and the second comparison result are false, the logical value obtained by the OR gate circuit 33 is false. The second controller 34 processes and analyzes this logical value. If it analyzes that the logical value output by the OR gate circuit 33 is true, it determines to send a noise reduction start signal to the first controller 40, that is, the first signal in the above embodiment, and determines to start the noise reduction function. If it analyzes that the logical value output by the OR gate circuit 33 is false, it determines not to send a noise reduction start signal to the first controller 40, or sends other signals to the first controller 40, such as the second signal in the above embodiment, and determines not to start the noise reduction function.

[0056] Therefore, the setting of the OR gate circuit 33 enables the noise reduction function to be started as long as any one of the noise signals reaches the standard that requires noise reduction, covering all types that require noise reduction, that is, the type in which the feedforward noise signal reaches the noise reduction standard, the type in which the feedback noise signal reaches the noise reduction standard, and the type in which both the feedforward noise signal and the feedback noise signal reach the noise reduction standard. Furthermore, the subsequent noise reduction circuit can perform noise reduction in a timely manner, and the accuracy of judging the start of the noise reduction function is improved. Moreover, the second controller 34 only needs to perform simple analysis and judgment based on the logical value to determine whether to start the noise reduction function, with a small amount of calculation and simple logic.

[0057] Optionally, the second controller 34 is not provided in the noise reduction self-start circuit 30, and the function of the second controller 34 is implemented by the first controller 40. That is, the OR gate circuit 33 directly sends the logical value to the first controller 40, and the first controller 40 makes judgments and analyzes according to the logical value. If the logical value is true, the noise reduction function is started, and then the first controller 40 controls the corresponding noise reduction circuits according to the feedforward noise signal and the feedback noise signal respectively to implement the noise reduction function.

[0058] Please refer to Figure 4 , Figure 4 which is a schematic circuit structure diagram of one of the earphone noise reduction circuits provided by the embodiments of the present invention. As Figure 4As shown in the figure, the feedback comparison circuit 31 includes a feedback comparator U1. The non-inverting input terminal of the feedback comparator U1 is electrically connected to the feedback noise reduction circuit 10. This non-inverting input terminal is used to obtain the feedback noise signal. The inverting input terminal of the feedback comparator U1 is used to obtain the first reference value. The output terminal of the feedback comparator U1 is electrically connected to the first input terminal of the OR gate circuit 33, and is used to output the first comparison result and transmit this first comparison result to the first input terminal of the OR gate circuit 33.

[0059] Optionally, the feedforward comparison circuit 32 includes a feedforward comparator U2. The non-inverting input terminal of the feedforward comparator U2 is electrically connected to the feedforward noise reduction circuit 20 and is used to obtain the feedforward noise signal. The inverting input terminal of the feedforward comparator U2 is used to obtain the second reference value. The output terminal of the feedforward comparator U2 is electrically connected to the second input terminal of the OR gate circuit 33. The output terminal of the feedforward comparator U2 is used to output the second comparison result and transmit the second comparison result to the second input terminal of the OR gate circuit 33.

[0060] The OR gate circuit 33 can be implemented by different methods, including diode implementation, switch implementation, CMOS logic implementation, etc. A multi-input OR gate can also be implemented by cascading multiple OR gates. In the embodiments of the present invention, it can also be implemented using an existing chip, such as the OR gate D in the figure. Here, the implementation method of the OR gate circuit 33 is not limited and is set by the user according to needs.

[0061] The feedback comparator U1 compares the feedback noise signal with the first reference value to obtain the first comparison result. The feedforward comparator U2 compares the feedforward noise signal with the second reference value to obtain the second comparison result. The OR gate D then performs a logical OR operation on the first comparison result and the second comparison result to obtain a logical value, and transmits this logical value to the second controller 34. The second controller 34 processes and analyzes this logical value, and determines whether to activate the noise reduction function according to this logical value. If the logical value is true, it is determined to activate the noise reduction function. If the logical value is false, it is determined not to activate the noise reduction function.

[0062] Optionally, the feedback noise reduction circuit 10 includes a feedback microphone MIC1, a feedback filter B1, and a first switch S1. Among them, the feedback microphone MIC1 is electrically connected to the feedback filter B1 and the feedback comparison circuit 31 respectively. Specifically, the feedback microphone MIC1 is electrically connected to the feedback filter B1 and the non-inverting input terminal of the feedback comparator U1 respectively. This feedback microphone MIC1 is used to collect the feedback noise signal;

[0063] One end of the feedback filter B1 is electrically connected to the first switch S1, and the other end is electrically connected to the feedback microphone MIC1 and the feedback comparison circuit 31 respectively. Specifically, the other end is electrically connected to the feedback microphone MIC1 and the non-inverting input terminal of the feedback comparator U1 respectively. The feedback filter B1 is used to filter and invert the feedback noise signal to obtain a feedback noise reduction signal, and the waveform amplitude of the feedback noise reduction signal is the same as that of the feedback noise signal, but the phase is opposite.

[0064] The feedback filter B1 is one of the important components of the noise reduction circuit, and its performance determines the noise reduction depth of the earphone. In actual application scenarios, the noise waveform changes at any time, and the application range of the fixed-frequency band filter is relatively narrow. Therefore, the above-mentioned feedback filter B1 is preferably an adaptive noise reduction filter, which can track the characteristics of the noise such as frequency, phase, and amplitude at any time, so as to achieve long-lasting and stable noise reduction.

[0065] The first end of the first switch S1 is electrically connected to the feedback filter B1, the second end of the first switch S1 is electrically connected to the speaker 200, and the control end of the first switch S1 is electrically connected to the first controller 40. When the first switch S1 is in the conducting working state, the feedback noise reduction signal is transmitted to the speaker 200. At this time, the feedback noise reduction circuit 10 is in the noise reduction working state. When the feedback noise reduction signal with the same waveform amplitude and opposite phase as the feedback noise signal is transmitted to the speaker 200, it cancels out the feedback noise signal transmitted to the speaker 200, realizing the feedback noise reduction function, that is, the in-ear noise reduction function.

[0066] The working state of the first switch S1 is controlled by the first controller 40. Specifically, when receiving the noise reduction start signal, the first controller 40 controls the working state of the first switch S1 according to the feedback noise signal and the first preset threshold. That is, after the noise reduction self-starting circuit 30 determines to start the noise reduction function and sends the noise reduction start signal to the first controller 40, the first controller 40 controls the conduction and disconnection of the first switch S1 according to the feedback noise signal and the first preset threshold. If the feedback noise signal is greater than or equal to the first preset threshold, the first controller 40 controls the first switch S1 to conduct for feedback noise reduction. If the feedback noise signal is less than the first preset threshold, the first controller 40 controls the first switch S1 to disconnect, and there is no need for feedback noise reduction. Among them, the specific value of the first preset threshold can be set by the user according to needs. The first switch S1 can be a contactor, a relay, an electronic switch, a delay switch, an optical switch, a touch switch, a proximity switch, a double-control switch, etc.

[0067] Optionally, please continue to refer to Figure 4, the circuit composition and working principle of the feedforward noise reduction circuit 20 are similar to those of the feedback noise reduction circuit 10. The feedforward noise reduction circuit 20 includes a feedforward microphone MIC2, a feedforward filter B2, and a second switch S2. Among them, the feedforward microphone MIC2 is electrically connected to the feedforward filter B2 and the feedforward comparison circuit 32 respectively, and the feedforward microphone MIC2 is used to collect feedforward noise signals.

[0068] One end of the feedforward filter B2 is electrically connected to the second switch S2, and the other end is electrically connected to the feedforward microphone MIC2 and the feedforward comparison circuit 32 respectively. The feedforward filter B2 is used to filter and invert the feedforward noise signal to obtain a feedforward noise reduction signal. The feedforward filter B2 is also preferably an adaptive noise reduction filter.

[0069] The first end of the second switch S2 is electrically connected to the feedforward filter B2, the second end of the second switch S2 is electrically connected to the speaker 200, and the control end of the second switch S2 is electrically connected to the first controller 40. When the second switch S2 is in the on working state, the feedforward noise reduction signal is transmitted to the speaker 200, and the feedforward noise reduction circuit 20 is in the noise reduction working state. The feedforward microphone MIC2 collects the external ear environmental noise. After being processed in the time domain and frequency domain by the feedforward filter B2, a feedforward noise reduction signal with the same amplitude and opposite phase as the noise waveform transmitted into the ear by the environmental noise is obtained. The feedforward noise reduction signal cancels out the external ear environmental noise signal entering the ear, realizing the feedforward noise reduction function.

[0070] Similarly, the on and off of the second switch S2 are controlled by the first controller 40. When receiving a noise reduction start signal, the first controller 40 controls the working state of the second switch S2 according to the feedforward noise signal and the second preset threshold. If the feedforward noise signal is greater than or equal to the second preset threshold, the first controller 40 controls the second switch S2 to conduct for feedforward noise reduction. If the feedforward noise signal is less than the second preset threshold, it controls the second switch S2 to disconnect, and there is no need for feedforward noise reduction. Among them, the specific value of the second preset threshold can be set by the user according to needs. The second switch S2 can be of types such as contactors, relays, electronic switches, delay switches, photoelectric switches, tactile switches, proximity switches, and double-control switches.

[0071] Please continue to refer to Figure 4 , combined with Figure 4 , the working principle of this noise reduction circuit can be described as follows:

[0072] The feedforward microphone MIC2 collects the feedforward noise signal, i.e., the external ear environmental noise signal. This feedforward noise signal is transmitted to the non-inverting input terminal of the feedforward comparator U2, where it is compared with the second reference value. If the feedforward noise signal is greater than or equal to the second reference value, a logic 1 (high-level signal) is obtained; if the feedforward noise signal is less than the second reference value, a logic 0 (low-level signal) is obtained. This logical result is transmitted to the second input terminal of the OR gate D.

[0073] Similarly, the feedback microphone MIC1 collects the feedback noise signal, i.e., the internal ear noise signal. This feedback noise signal is transmitted to the non-inverting input terminal of the feedback comparator U1, where it is compared with the first reference value. If the feedback noise signal is greater than or equal to the first reference value, a logic 1 (level signal) is obtained; if the feedback noise signal is less than the first reference value, a logic 0 (low-level signal) is obtained. This logical result is transmitted to the first input terminal of the OR gate D.

[0074] The OR gate D performs a logical OR operation on the logical results output by the feedback comparator U1 and the feedforward comparator U2 to obtain a logical value, which is transmitted to the second controller 34. The second controller 34 determines whether to activate the noise reduction function. If the logical value is true, it is determined to activate the noise reduction function and a noise reduction start signal is sent to the first controller 40. If the logical value is false, it is determined not to activate the noise reduction function. That is, as long as any one of the feedforward noise signal and the feedback noise signal reaches the standard for noise reduction, the second controller 34 determines to activate the noise reduction function. Only when both noise signals do not reach the standard for noise reduction will the second controller 34 determine not to activate the noise reduction function.

[0075] If the first controller 40 receives the noise reduction start signal, it then controls the working state of the first switch S1 according to the feedback noise signal and the first preset threshold, and controls the working state of the second switch S2 according to the feedforward noise signal and the second preset threshold. Specifically, if the feedback noise signal is greater than or equal to the first preset threshold, the first controller 40 controls the first switch S1 to conduct for feedback noise reduction; if the feedback noise signal is less than the first preset threshold, it controls the first switch S1 to disconnect, and no feedback noise reduction is required.

[0076] If the feedforward noise signal is greater than or equal to the second preset threshold, the first controller 40 controls the second switch S2 to conduct for feedforward noise reduction; if the feedforward noise signal is less than the second preset threshold, it controls the second switch S2 to disconnect, and no feedforward noise reduction is required.

[0077] If the first controller 40 controls the first switch S1 to conduct for feedback noise reduction, after the feedback noise signal is processed by the feedback filter B1 in the time domain and frequency domain, a feedback noise reduction signal with the same waveform amplitude and opposite phase as the feedback noise signal is obtained. This feedback noise reduction signal is transmitted to the speaker 200 through the first switch S1 to cancel out the feedback noise signal, so that the audio signal after feedback noise reduction is played at the speaker 200;

[0078] If the first controller 40 controls the second switch S2 to conduct for feedforward noise reduction, after the feedforward noise signal is processed by the feedforward filter B2 in the time domain and frequency domain, a feedforward noise reduction signal with the same waveform amplitude and opposite phase as the noise waveform of the feedforward noise signal entering the ear is obtained. This feedforward noise reduction signal is transmitted to the speaker 200 through the second switch S2 to cancel out the noise of the feedforward noise signal entering the ear, so that the audio signal after feedforward noise reduction is played at the speaker 200;

[0079] Generally, the feedforward noise reduction circuit 20 cannot achieve complete noise reduction. Further deep noise reduction is achieved by the feedback noise reduction circuit 10. The feedback microphone MIC1 of the feedback noise reduction circuit 10 collects the residual noise in the ear, that is, the feedback noise signal, for deep noise reduction.

[0080] In summary, the noise reduction circuit of this headphone can achieve the noise reduction self-start function only through the circuit, and also uses two types of noise signals as the basis for starting the noise reduction function. Compared with the circuit that uses a single noise signal as the basis for starting the noise reduction function, it can start the noise reduction function more accurately, and thus can reduce noise in time and improve the user experience. At the same time, when the noise reduction self-start circuit determines to start the noise reduction function, the first controller is used to control the working states of the feedback noise reduction circuit and the feedforward noise reduction circuit according to the feedback noise signal and the feedforward noise signal respectively, so that the feedback noise reduction circuit and the feedforward noise reduction circuit can reduce the respective noise signals, further improving the noise reduction function and effectively improving the user experience.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other changes in different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A headphone noise reduction circuit is applied to a headphone device. Characterized in that, Comprising: A feedback noise reduction circuit, a feedforward noise reduction circuit, a noise reduction self-starting circuit, and a first controller; The feedback noise reduction circuit is electrically connected to the noise reduction self-starting circuit, the speaker, and the first controller respectively. The feedback noise reduction circuit is used to obtain a feedback noise signal and reduce the feedback noise signal; The feedforward noise reduction circuit is electrically connected to the noise reduction self-starting circuit, the speaker, and the first controller respectively. The feedforward noise reduction circuit is used to obtain a feedforward noise signal and reduce the feedforward noise signal; The noise reduction self-starting circuit is also electrically connected to the first controller, and is used to determine whether to start the noise reduction function according to the feedback noise signal and the feedforward noise signal; And When the noise reduction self-starting circuit determines to start the noise reduction function, the first controller is used to control the working states of the feedback noise reduction circuit and the feedforward noise reduction circuit respectively according to the feedback noise signal and the feedforward noise signal; The noise reduction self-starting circuit includes: a feedback comparison circuit, a feedforward comparison circuit, an OR gate circuit, and a second controller; The feedback comparison circuit is electrically connected to the feedback noise reduction circuit and the first input end of the OR gate circuit respectively. The feedback comparison circuit is used to obtain the feedback noise signal and compare the feedback noise signal with a first reference value to obtain a first comparison result; The feedforward comparison circuit is electrically connected to the feedforward noise reduction circuit and the second input end of the OR gate circuit respectively. The feedforward comparison circuit is used to obtain the feedforward noise signal, compare the feedforward noise signal with a second reference value to obtain a second comparison result; The output end of the OR gate circuit is also electrically connected to the second controller. The OR gate circuit is used to perform a logical OR operation according to the first comparison result and the second comparison result to obtain a logical value; and The second controller is also electrically connected to the first controller. The second controller is used to determine whether to send a noise reduction start signal to the first controller according to the logical value; The second controller is also used for: If the logical value is true, it is determined to start the noise reduction function; If the logical value is false, it is determined not to start the noise reduction function.

2. The headphone noise reduction circuit according to claim 1, Characterized in that, The feedback comparison circuit includes a feedback comparator. The non-inverting input terminal of the feedback comparator is electrically connected to the feedback noise reduction circuit and is used to obtain the feedback noise signal; The inverting input terminal of the feedback comparator is used to obtain the first reference value; The output end of the feedback comparator is electrically connected to the first input end of the OR gate circuit.

3. The headphone noise reduction circuit according to claim 1, Characterized in that, The feedforward comparison circuit includes a feedforward comparator. The non-inverting input terminal of the feedforward comparator is electrically connected to the feedforward noise reduction circuit and is used to obtain the feedforward noise signal; The inverting input terminal of the feedforward comparator is used to obtain the second reference value; The output end of the feedforward comparator is electrically connected to the second input end of the OR gate circuit.

4. The headphone noise reduction circuit according to any one of claims 1-3, characterized in that, the feedback noise reduction circuit includes a feedback microphone, a feedback filter, and a first switch; the feedback microphone is electrically connected to the feedback filter and the feedback comparison circuit respectively, and the feedback microphone is used to collect the feedback noise signal; one end of the feedback filter is electrically connected to the first switch, and the other end is electrically connected to the feedback microphone and the feedback comparison circuit respectively. The feedback filter is used to filter and invert the feedback noise signal to obtain a feedback noise reduction signal; the first end of the first switch is electrically connected to the feedback filter, the second end of the first switch is electrically connected to the speaker, and the control end of the first switch is electrically connected to the first controller. When the first switch is in the on working state, the feedback noise reduction signal is transmitted to the speaker, and the feedback noise reduction circuit is in the noise reduction working state.

5. The headphone noise reduction circuit according to claim 4, characterized in that, the first controller is further configured to: when receiving the noise reduction start signal, control the working state of the first switch according to the feedback noise signal and a first preset threshold.

6. The headphone noise reduction circuit according to any one of claims 1-3, characterized in that, the feedforward noise reduction circuit includes a feedforward microphone, a feedforward filter, and a second switch; the feedforward microphone is electrically connected to the feedforward filter and the feedforward comparison circuit respectively, and the feedforward microphone is used to collect the feedforward noise signal; one end of the feedforward filter is electrically connected to the second switch, and the other end is electrically connected to the feedforward microphone and the feedforward comparison circuit respectively. The feedforward filter is used to filter and invert the feedforward noise signal to obtain a feedforward noise reduction signal; the first end of the second switch is electrically connected to the feedforward filter, the second end of the second switch is electrically connected to the speaker, and the control end of the second switch is electrically connected to the first controller. When the second switch is in the on working state, the feedforward noise reduction signal is transmitted to the speaker, and the feedforward noise reduction circuit is in the noise reduction working state.

7. The headphone noise reduction circuit according to claim 6, characterized in that, the first controller is further configured to: when receiving the noise reduction start signal, control the working state of the second switch according to the feedforward noise signal and a second preset threshold.

8. A headphone device, characterized in that, comprising: a speaker for playing an audio signal; and the headphone noise reduction circuit according to any one of claims 1-7, the headphone noise reduction circuit is electrically connected to the speaker for reducing noise of the audio signal.

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