Active noise reduction and unvarnished transmission switching device for Bluetooth headset

Abstract

The utility model discloses an active noise reduction and unvarnished transmission switching device of a Bluetooth earphone, which comprises an active noise reduction module for generating reverse sound waves to counteract noise from sound picked up by external sound, an unvarnished transmission module for processing the captured sound and then transmitting the sound to ears in real time, and an identification module for identifying behaviors of a user, the recognition module comprises a sound pickup unit for picking up voice vibration of the microphone; according to the utility model, the audio detection circuit is arranged to detect the audio of a human voice and judge whether a user is in a conversation state, and when the audio of the human voice is higher, the unvarnished transmission module is switched to serve as a signal processing link through the switching circuit, so that the voice is input as an information source by unvarnished transmission, namely, information obtained after impurity removal of an original external signal; and the active denoising or transparent transmission mode is automatically switched to meet the requirements of weakening the external sound and truly perceiving the external sound, so that the use safety of a user can be improved, and the method is suitable for a safe office or outdoor sports environment.

Description

Technical Field

[0001] This utility model relates to the field of Bluetooth headset noise reduction technology, specifically a Bluetooth headset active noise reduction and pass-through switching device. Background Technology

[0002] Bluetooth headphones primarily employ two noise-canceling technologies: active noise cancellation and passive noise cancellation. Passive noise cancellation uses physical structures to isolate external noise; for example, in-ear or over-ear headphones fit snugly in the ear canal or cover the ear to block noise from entering. Active noise cancellation uses microphones to capture ambient noise and generate inverse sound waves to cancel it out, thus reducing external interference. Because passive noise cancellation has limited effectiveness against low-frequency noise and relies heavily on a proper fit, active noise cancellation is currently the dominant method used in Bluetooth headphones.

[0003] A search revealed a smart sports noise-canceling Bluetooth headset disclosed in patent application publication number CN108076399A. The headset includes a Bluetooth headset body, a speaker, and a noise-canceling earpiece. The Bluetooth receiving circuit board and noise-canceling chip are housed inside the headset body, and the noise-canceling chip is connected to the sound acquisition unit inside the Bluetooth receiving circuit board and the speaker. Digital noise reduction is achieved through a digital low-pass filter circuit. The use of the noise-canceling earpiece and the noise-canceling chip enables noise reduction processing during audio output.

[0004] Active noise cancellation can significantly reduce low-frequency noise and enhance immersion, making it suitable for scenarios that require focus or noise isolation, such as commuting, working, and studying. However, it may cause ear pressure, and prolonged use may cause users to overlook surrounding safety hazards such as vehicle horns. Summary of the Invention

[0005] The purpose of this invention is to provide a Bluetooth headset active noise cancellation and pass-through switching device. By setting a mode that switches between active noise cancellation and pass-through, the Bluetooth headset can switch between safe and noisy environments, improving the immersive listening experience and the ability to perceive the external environment.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a Bluetooth headset active noise cancellation and pass-through switching device, including an active noise cancellation module that generates reverse sound waves to cancel noise from external sounds, a pass-through module that processes the captured sound and transmits it to the ear in real time, and a recognition module that recognizes user behavior.

[0007] The recognition module includes a sound pickup unit that picks up voice vibrations from a microphone, an audio detection circuit that infers whether the user is in a conversational environment based on the sound pickup unit, and a switching circuit that controls the music to be lowered and transmits ambient sound.

[0008] The active noise reduction module includes a feedforward microphone, a feedback microphone, and a digital signal processor responsible for analyzing noise frequency and phase and generating inverse sound waves. The feedforward microphone and the feedback microphone are both electrically connected to the digital signal processor.

[0009] The transparent transmission module includes a chip U1. The EXT terminal of the chip U1 is connected to a capacitor C1 and a resistor R1. One end of the capacitor C1 is grounded. The 15th pin of the chip U1 is connected to a resistor R3. The 14th pin of the chip U1 is connected to a resistor R4 and a light-emitting diode LED1. The resistor R4 and the light-emitting diode LED1 are connected in series. The XTAL terminal of the chip U1 is connected to a clock circuit.

[0010] The sound pickup unit includes an amplifier U5A. The non-inverting input terminal of the amplifier U5A is connected to a resistor R26 and a capacitor C8. The capacitor C8 is connected in parallel with the resistor R26. The inverting input terminal of the amplifier U5A is connected to a resistor R24. One end of the resistor R24 ​​is connected in series with a capacitor C7. A feedback resistor R28 is connected between the inverting input terminal and the output terminal of the amplifier U5A. One end of the capacitor C7 is connected to a microphone interface terminal.

[0011] The audio detection circuit includes transistors Q3 and Q4. A resistor R49 is connected to the collector of transistor Q3, a resistor R47 is connected to the base of transistor Q3, a capacitor C31 is connected to one end of the resistor R47, a resistor R50 and a resistor R51 are connected between the base of transistor Q4 and the base of transistor Q3, and a capacitor C37 is connected between the resistor R50 and the resistor R51.

[0012] The switching circuit includes resistors R61 and R63. One end of resistor R61 is provided with an interface L1 for the active noise cancellation module to access, and the other end of resistor R61 is connected to resistor R62 and capacitor C61. One end of resistor R63 is provided with an interface L2 for the pass-through module to access, and the other end of resistor R63 is connected to resistor R64 and capacitor C62. The switching circuit also includes an LF356 amplifier. The inverting input terminal of the LF356 amplifier is connected to resistor R66. One end of resistor R66 is connected to resistor R65 and transistor T1. One end of resistor R65 is connected in series with capacitor C63. Transistor T1 is a 2N3819 model, and the gate of transistor T1 is connected to resistor R68 and capacitor C64.

[0013] Preferably, the amplifier U5A is an LM358AM model.

[0014] Preferably, the chip U1 is an ESP8266EX model.

[0015] Preferably, the clock circuit includes a crystal resonator Y1, one end of which is connected to pin 28 of chip U1, and the other end of which is connected to pin 27 of chip U1. A capacitor C5 and an inductor L1 are connected to the LNA terminal of chip U1, and a capacitor C6 is connected to one end of capacitor C5.

[0016] Compared with the prior art, the beneficial effects of this utility model are:

[0017] This invention uses an audio detection circuit to detect the pitch of human voice audio and determine whether the user is in conversation. When the human voice audio is high, a switching circuit switches the pass-through module as the signal processing link, so that the sound is input as the information source after the original external signal has been processed by pass-through, which facilitates the user's capture of external information. At the same time, an amplifier circuit controls the music volume to decrease, improving the Bluetooth headset's ability to distinguish external information. Compared with traditional active noise-canceling headphones, this Bluetooth headset can automatically switch between active noise cancellation and pass-through modes according to the user's environment to meet the needs of weakening external sounds while still realistically perceiving them. This improves user safety and is suitable for safe office or outdoor sports environments. Attached Figure Description

[0018] Figure 1 This is a system structure diagram of this utility model;

[0019] Figure 2 This is a circuit diagram of the sound pickup unit of this utility model;

[0020] Figure 3 This is the circuit diagram of the transparent transmission module of this utility model;

[0021] Figure 4 This is a circuit diagram of the audio detection circuit of this utility model;

[0022] Figure 5 This is a circuit diagram showing the switching between the transparent transmission module and the active noise reduction module of this utility model;

[0023] Figure 6 This is the circuit diagram for controlling the volume of this utility model. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] Please see Figure 1-6 This utility model provides a technical solution: a Bluetooth headset active noise cancellation and pass-through switching device, including an active noise cancellation module that generates reverse sound waves to cancel noise from external sounds, a pass-through module that transmits the captured sound to the ear in real time after processing, and a recognition module that recognizes user behavior.

[0026] The recognition module includes a sound pickup unit that picks up voice vibrations from a microphone, an audio detection circuit that infers whether the user is in a conversational environment based on the sound pickup unit, and a switching circuit that controls the music to be lowered and transmits ambient sound.

[0027] By configuring the sound pickup unit and using the microphone's vibration signal as the input source, the audio detection circuit detects the audio of the human voice. When the audio is high, it is determined that the user is in conversation mode. At this time, the switching circuit changes the noise cancellation mode of the Bluetooth headset, as follows:

[0028] The sound pickup unit includes an amplifier U5A, which is an LM358AM model. The non-inverting input of the amplifier U5A is connected to a resistor R26 and a capacitor C8, which are connected in parallel with the resistor R26. The inverting input of the amplifier U5A is connected to a resistor R24, and a capacitor C7 is connected in series with one end of the resistor R24. A feedback resistor R28 is connected between the inverting input and output of the amplifier U5A. One end of the capacitor C7 is connected to a microphone interface.

[0029] The microphone's positive terminal is connected to a 5V power supply via resistor R23, while the negative terminal is grounded. The output signal is connected to the amplifier input via coupling capacitor C8 to isolate the DC component. Through the coordinated operation of the sound pickup unit and the audio detection circuit, the system can capture the user's vocal cord vibration characteristics and changes in ambient sound in real time. When user voice communication or sudden dangerous sound sources (such as vehicle horns) are detected, the switching circuit can be triggered to activate the pass-through mode within a short time, effectively solving safety hazards in active noise cancellation scenarios.

[0030] The transparent transmission module includes a chip U1, which is an ESP8266EX chip. The EXT terminal of the chip U1 is connected to a capacitor C1 and a resistor R1. One end of the capacitor C1 is grounded. The 15th pin of the chip U1 is connected to a resistor R3. The 14th pin of the chip U1 is connected to a resistor R4 and a light-emitting diode LED1. The resistor R4 and the light-emitting diode LED1 are connected in series. The XTAL terminal of the chip U1 is connected to a clock circuit.

[0031] The Y1 crystal resonator requires an external 26MHz passive crystal oscillator and a 10pF load capacitor to ensure a stable clock signal. By integrating WiFi / BLE dual-mode with the ESP8266EX chip, the transmission latency is reduced. By setting the pass-through mode, ambient sound can be retained while playing music, balancing music experience with external perception. It is suitable for scenarios where vigilance is required, such as walking, talking, or waiting for a vehicle.

[0032] The clock circuit includes a crystal resonator Y1. One end of the crystal resonator Y1 is connected to pin 28 of the chip U1, and the other end of the crystal resonator Y1 is connected to pin 27 of the chip U1. A capacitor C5 and an inductor L1 are connected to the LNA terminal of the chip U1, and a capacitor C6 is connected to one end of the capacitor C5.

[0033] The active noise reduction module includes a feedforward microphone, a feedback microphone, and a digital signal processor responsible for analyzing noise frequency and phase and generating inverse sound waves. The feedforward microphone and the feedback microphone are both electrically connected to the digital signal processor.

[0034] The active noise cancellation module uses a feedforward microphone located on the outside of the earphone to collect ambient noise in real time, while a feedback microphone inside the earcups monitors residual noise and optimizes the cancellation effect. This active noise cancellation module is similar to existing technologies. Through the adaptive filtering algorithm core of the digital signal processor, the sound parameters are dynamically adjusted to cope with noise frequency fluctuations. The generating unit outputs an inverse sound wave, which is superimposed on the original noise to achieve acoustic noise cancellation.

[0035] The audio detection circuit includes transistors Q3 and Q4. A resistor R49 is connected to the collector of transistor Q3, and a resistor R47 is connected to the base of transistor Q3. A capacitor C31 is connected to one end of the resistor R47. Resistors R50 and R51 are connected between the base of transistor Q4 and the base of transistor Q3. A capacitor C37 is connected between resistors R50 and R51.

[0036] Transistors Q3 and Q4 form a differential amplifier structure with a common-mode rejection ratio >80dB, effectively distinguishing human voice (300-3400Hz) from environmental noise. Capacitor C37 and resistors R50 and R51 form a bandpass characteristic, which can accurately extract speech features.

[0037] The switching circuit includes resistors R61 and R63. One end of resistor R61 is provided with an interface L1 for the active noise cancellation module to access. The other end of resistor R61 is connected to resistor R62 and capacitor C61. One end of resistor R63 is provided with an interface L2 for the transparent transmission module to access. The other end of resistor R63 is connected to resistor R64 and capacitor C62.

[0038] By setting up an LF356 amplifier in conjunction with transistor T1, a signal switching with a dynamic range of 110dB and a switching time of <50μs is achieved. Capacitor C63 and resistor R65 form a soft-start circuit to eliminate switching pops.

[0039] The switching circuit also includes an LF356 amplifier. The inverting input terminal of the LF356 amplifier is connected to a resistor R66. One end of the resistor R66 is connected to a resistor R65 and a transistor T1. One end of the resistor R65 is connected in series with a capacitor C63. The transistor T1 is a 2N3819 model. The gate of the transistor T1 is connected to a resistor R68 and a capacitor C64.

[0040] During use, the sound pickup unit detects the vibration of the user's microphone or a sudden dangerous sound source such as a vehicle horn. The audio detection circuit detects high frequencies, and when the frequency is high, it determines that the user is talking or in a dangerous situation. At this time, the LF356 amplifier and transistor T1 achieve a signal switching of 110dB dynamic range, switching the noise cancellation mode of the Bluetooth headset from active noise cancellation to pass-through mode. Compared with traditional noise-canceling Bluetooth headsets, this Bluetooth headset switching circuit can reduce the safety hazards in active noise cancellation scenarios and optimize the use effect of Bluetooth headsets.

[0041] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A Bluetooth earphone active noise reduction and transmission switching device, characterized in that: The active noise reduction module includes reverse sound wave generated by picking up sound of external sound, the transparent transmission module which transmits the sound to the ear in real time after processing according to the captured sound, and the recognition module which recognizes the user behavior; The recognition module includes a sound pickup unit for picking up voice vibration sound picked up by the microphone, an audio detection circuit for speculating whether the user is in a conversation environment according to the sound pickup unit, and a switching circuit for controlling the music to be reduced and the environment sound to be transmitted; The active noise reduction module includes a feedforward microphone, a feedback microphone, and a digital signal processor responsible for analyzing noise frequency and phase and generating a reverse sound wave, wherein the feedforward microphone and the feedback microphone are electrically connected with the digital signal processor; The transparent transmission module includes a chip U1, one end of the capacitor C1 is grounded, the 15th pin of the chip U1 is connected with a resistor R3, the 14th pin of the chip U1 is connected with a resistor R4 and a light emitting diode LED1, the resistor R4 and the light emitting diode LED1 are connected in series, and the XTAL end of the chip U1 is connected with a clock circuit; The sound pickup unit includes an amplifier U5A, the same direction input end of the amplifier U5A is connected with a resistor R26 and a capacitor C8, the capacitor C8 and the resistor R26 are connected in parallel, the reverse input end of the amplifier U5A is connected with a resistor R24, one end of the resistor R24 is connected with a capacitor C7, the feedback resistor R28 is connected between the reverse input end and the output end of the amplifier U5A, and one end of the capacitor C7 is connected with a microphone interface end; The audio detection circuit includes a triode Q3 and a triode Q4, the collector of the triode Q3 is connected with a resistor R49, the base of the triode Q3 is connected with a resistor R47, one end of the resistor R47 is connected with a capacitor C31, the base of the triode Q4 is connected with the base of the triode Q3, and the resistor R50 and the resistor R51 are connected between the base of the triode Q4 and the base of the triode Q3; The switching circuit includes a resistor R61 and a resistor R63, one end of the resistor R61 is provided with an interface L1 for connecting the active noise reduction module, the other end of the resistor R61 is connected with a resistor R62 and a capacitor C61, one end of the resistor R63 is provided with an interface L2 for connecting the transparent transmission module, the other end of the resistor R63 is connected with a resistor R64 and a capacitor C62, and the switching circuit further includes an LF356 amplifier, the reverse input end of the LF356 amplifier is connected with a resistor R66, one end of the resistor R66 is connected with a resistor R65 and a transistor T1 respectively, one end of the resistor R65 is connected with a capacitor C63, the transistor T1 is of a 2N3819 model, and the G pole of the transistor T1 is connected with a resistor R68 and a capacitor C64.

2. The Bluetooth earphone active noise reduction and transmission switching device according to claim 1, characterized in that: The amplifier U5A is of an LM358AM model.

3. The Bluetooth earphone active noise reduction and transmission switching device according to claim 2, characterized in that: The chip U1 is of an ESP8266EX model.

4. The Bluetooth earphone active noise reduction and transmission switching device according to claim 3, characterized in that: The clock circuit comprises a crystal resonator Y1, one end of the crystal resonator Y1 is connected with the 28th pin of a chip U1, the other end of the crystal resonator Y1 is connected with the 27th pin of the chip U1, the LNA end of the chip U1 is connected with a capacitor C5 and an inductor L1, one end of the capacitor C5 is connected with a capacitor C6.

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