Automobile sound equipment and noise reduction method thereof

Abstract

The invention discloses automobile sound equipment and a noise reduction method thereof, and belongs to the technical field of automobile noise reduction. The sound equipment comprises a loudspeaker, and a noise reduction control circuit, an audio playing circuit and a control chip which are electrically connected with the loudspeaker, the loudspeaker comprises a driving unit, a positive electrode interface and a negative electrode interface; the noise reduction control circuit comprises a shunt resistor, a shunt capacitor and a shunt inductor which are sequentially connected in series; wherein the shunt resistor is connected with the positive electrode interface through the first execution chip, and the shunt inductor is connected with the negative electrode interface through the second execution chip; the output end of the audio playing circuit is connected with the positive electrode interface through the first execution chip, and the backflow end of the audio playing circuit is connected with the negative electrode interface through the second execution chip. The control chip controls the first execution chip and the second execution chip to be switched synchronously, so that one of the audio playing circuit and the noise reduction control circuit is switched on. According to the invention, the loudspeaker is used for active noise reduction in the non-audio playing state through circuit switching, and no extra noise reduction equipment needs to be installed.

Description

Technical Field

[0001] This invention relates to the field of automotive noise reduction, and in particular to an automotive audio device and its noise reduction method. Background Technology

[0002] Cars generate a significant amount of noise while driving, especially at high speeds or on roads with poor conditions. This noise primarily originates from the engine, wind resistance, tire-road friction, and vibrations within the vehicle. Low-frequency noise, in particular, due to its longer wavelength and stronger penetrating power, is especially prone to interfering with passengers, impacting the driving experience and ride comfort.

[0003] Noise control technologies are mainly divided into two categories: passive and active. Traditional passive noise control technologies, such as using porous sound-absorbing materials or resonant structures, require a certain volume and space to achieve effective low-frequency noise absorption. Active noise control (ANC) technology, on the other hand, introduces a controlled sound source to interact with the original noise source or noise field to reduce noise levels; this method is also known as active noise control. The main advantages of ANC technology are its deployment flexibility and high efficiency in low-frequency noise suppression. However, its disadvantages include system complexity, requiring sophisticated controllers and additional sensors. Furthermore, the effectiveness of active noise reduction may be affected by changes in the surrounding environment, leading to stability issues. Therefore, it is necessary to conduct research on novel thin-layer sound-absorbing structures to improve the noise reduction efficiency of low-frequency noise in enclosed spaces. Summary of the Invention

[0004] Therefore, this invention proposes a car audio device and its noise reduction method, which enables the audio device to absorb low-frequency sound waves without affecting its original function.

[0005] To address the aforementioned technical problems, the present invention provides the following technical solution: A car audio device includes: a speaker, a noise reduction control circuit, an audio playback circuit, and a control chip electrically connected to the speaker; the speaker includes a driver unit, a positive interface, and a negative interface; the noise reduction control circuit includes a shunt resistor, a shunt capacitor, and a shunt inductor connected in series; wherein the shunt resistor is connected to the positive interface through a first execution chip, and the shunt inductor is connected to the negative interface through a second execution chip; the output terminal of the audio playback circuit is connected to the positive interface through the first execution chip, and the return terminal of the audio playback circuit is connected to the negative interface through the second execution chip; the control chip controls the first execution chip and the second execution chip to switch synchronously, realizing the selective activation of the audio playback circuit and the noise reduction control circuit.

[0006] In some embodiments of the present invention, an operational amplifier is provided between the shunt resistor and the shunt capacitor.

[0007] In some embodiments of the present invention, the noise reduction control circuit includes at least two sets of noise reduction control sub-circuits with different parameters. Each set of noise reduction control sub-circuits has the same circuit components, but at least one component in the circuit components has a different parameter value.

[0008] In some embodiments of the present invention, the control chip controls the first execution chip and the second execution chip according to the vehicle noise signal, the vehicle status signal and the vehicle audio signal, so as to selectively connect the audio playback circuit and the noise reduction control circuit.

[0009] In some embodiments of the present invention, the control chip controls the first execution chip and the second execution chip according to the driver's audio playback habits data, so as to selectively connect the audio playback circuit and the noise reduction control circuit.

[0010] In some embodiments of the present invention, the driving unit includes a magnet, a voice coil, a paper cone, a dust cover, and a T-shaped iron.

[0011] In some embodiments of the present invention, the vehicle noise signal is obtained by a comprehensive judgment of one or more of the following: vehicle microphone, engine speed signal, and vehicle speed signal.

[0012] This invention also provides a noise reduction method for car audio equipment, comprising the following steps: S1. Real-time monitoring of vehicle system status; S2 If the vehicle is turned off, the audio playback circuit is disconnected from the speaker, and step S4 is executed; S3. If the vehicle infotainment system is powered on, detect the audio signal. If the detected audio signal strength is greater than the set threshold, control the execution chip to disconnect the noise reduction control circuit and keep the audio playback circuit connected. If the detected audio signal strength is less than the set threshold, proceed to step 4. S4. Determine whether to perform noise reduction operation based on the collected noise signal. If the decibel value of the noise signal is greater than the set threshold, control the noise reduction control circuit to connect to the speaker.

[0013] In some embodiments of the present invention, in step S4, a noise reduction control circuit matching the detected noise peak frequency is turned on.

[0014] In some embodiments of the present invention, the driver's audio timing playback habit data is identified based on data from a vehicle driving habit database. Based on the audio timing playback habit data and real-time time control, it is determined whether to perform noise reduction operation. If the real-time time reaches the audio timing playback time, the noise reduction control circuit is disconnected and the audio playback circuit is connected.

[0015] The technical solution of the present invention has the following technical effects compared with the prior art: The car audio equipment provided by this invention utilizes existing speakers as noise reduction units, eliminating the need for additional hardware and reducing system and space costs. Simultaneously, through intelligent switching, the noise reduction control circuit and audio control circuit can be selectively activated, preventing noise reduction control from affecting audio playback and resulting in a better user experience. The synchronous switching design and component optimization reduce circuit conflicts and equipment wear, extending the lifespan of the audio equipment. Attached Figure Description

[0016] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, which will help to understand the purpose and advantages of the present invention, wherein: Figure 1 This is a circuit connection diagram of a specific embodiment of the car audio device of the present invention; Figure 2 This is a schematic diagram of a specific embodiment of the loudspeaker in the car audio equipment of the present invention; Figure 3 This is a schematic diagram of a specific embodiment of the loudspeaker in the car audio equipment of the present invention; Figure 4 A flowchart illustrating a specific implementation of the noise reduction method for a car audio device according to the present invention; Figure 5 This is a flowchart illustrating another specific embodiment of the noise reduction method for car audio equipment according to the present invention. Detailed Implementation

[0017] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] like Figure 1 The diagram illustrates a specific embodiment of the car audio device of the present invention. This car audio device reduces vehicle noise during operation without affecting the use of existing audio equipment. The device includes a speaker 1, a noise reduction control circuit 2, an audio playback circuit 3, and a control chip Q3. The speaker 1 employs a moving-coil structure, including a driver unit, a positive interface 16, and a negative interface 17. The voice coil 12 in the driver unit is electrically connected to the positive and negative interfaces 17, converting electrical signals into mechanical vibrations. The noise reduction control circuit 2 consists of a shunt resistor, a shunt capacitor, and a shunt inductor connected in series to form an RLC series resonant circuit. This circuit is connected to the positive and negative interfaces 17 of the speaker 1 via a first execution chip Q1 and a second execution chip Q2. Specifically, the shunt resistor is connected to the positive interface 16 via the first execution chip Q1, and the shunt inductor is connected to the negative interface 17 via the second execution chip Q2. The output of the audio playback circuit 3 is connected to the positive interface 16 via the first execution chip Q1, and the return terminal is connected to the negative interface 17 via the second execution chip Q2. The control chip Q3 (e.g., a microcontroller MCU) outputs a control signal to drive the first execution chip Q1 and the second execution chip Q2 to switch synchronously, enabling selective activation of the audio playback circuit 3 and the noise reduction control circuit 2. When the noise reduction control circuit 2 is activated, the speaker 1, acting as a passive acoustic load, absorbs low-frequency sound waves (such as engine noise or road noise) at specific frequencies through the resonant characteristics of the RLC circuit, converting sound energy into heat energy for dissipation. This car audio device, through simple circuit switching, allows the speaker 1 to be used for active noise reduction in non-audio playback mode, exhibiting high absorption efficiency, especially for low-frequency noise (typically in the 20-200Hz range), eliminating the need for additional noise reduction equipment and saving cost and space. Simultaneously, the synchronous switching avoids circuit conflicts, ensuring stable operation of the device. Furthermore, the noise reduction control circuit 2 is integrated into the existing PCB board of the audio device, compatible with existing car audio installation interfaces, with an overall thickness of ≤5cm and a volume 60% smaller than traditional passive noise reduction structures, making it suitable for the limited installation space in passenger vehicles.

[0022] Specifically, in one optional embodiment, an operational amplifier (not shown in the figure) is provided between the shunt resistor and the shunt capacitor in the noise reduction control circuit 2. This operational amplifier is configured as a voltage follower or amplifier circuit to adjust the impedance characteristics of the RLC circuit and enhance the response sensitivity to specific frequency signals. Specifically, the output terminal of the operational amplifier is connected to the shunt capacitor, and the input terminal is connected to the shunt resistor. The gain is adjusted through a feedback network, thereby optimizing the width and depth of the noise reduction bandwidth. The introduction of the operational amplifier improves the flexibility and accuracy of the noise reduction control circuit 2, enabling the system to more accurately match the vehicle noise frequency and improve low-frequency absorption efficiency. Simultaneously, the operational amplifier can compensate for deviations in circuit component parameters, ensuring consistent noise reduction performance.

[0023] Specifically, in one optional embodiment, the noise reduction control circuit 2 includes at least two sets of noise reduction control sub-circuits with different parameters. Each set of sub-circuits includes a shunt resistor, a shunt capacitor, and a shunt inductor, but the parameter values ​​of at least one component are different. For example, the shunt capacitor value C of the first sub-circuit A is different. S The shunt inductance value is 100-120μF. S The shunt resistance value is 10-20mH. S The current is 10-20Ω, used to absorb low-frequency noise around 50-100Hz; the shunt capacitor value C of the second sub-circuit B. S1 The shunt inductance value is 10-20μF. S1 The shunt resistance value is 10-20mH. S1 The impedance is 20-30Ω, used to absorb noise in the 100-300Hz range. The control chip Q3 selects and activates different sub-circuits via a multiplexer within the execution chip, achieving multi-band noise reduction. Through multiple sets of adjustable noise reduction sub-circuits, the system can cover a wider noise frequency range, adapting to the noise characteristics of different vehicle operating conditions (such as idling and high-speed driving). This design enhances the adaptive capability of noise reduction, avoiding the limitations of noise reduction effects caused by fixed parameters in a single circuit.

[0024] Specifically, in one embodiment, the speaker 1 driver unit adopts a classic moving-coil structure, comprising a magnetic circuit system and a vibration system. The magnetic circuit system includes a magnet 11 and a T-shaped iron 15. The vibration system includes a voice coil 12, a paper cone 13, and a dust cover 14. More specifically, the magnet 11 is bonded to the T-shaped iron 15 with epoxy resin adhesive, the voice coil 12 is precisely inserted into the magnetic gap using a special fixture, the voice coil 12 and the paper cone 13 are bonded with epoxy resin, and the dust cover 14 is bonded to the center of the paper cone 13 with flexible adhesive. When the noise reduction control circuit 2 is activated, the voice coil 12 generates an anti-phase sound wave under the drive of the RLC circuit, canceling out noise interference; when the audio playback circuit 3 is activated, the driver unit normally restores the audio signal. The optimized design of the driver unit ensures the high efficiency performance of the speaker 1 in both noise reduction and audio playback modes. The T-shaped iron 15 enhances the uniformity of the magnetic field, while the paper cone 13 and dust cover 14 provide a good acoustic response, resulting in high fidelity for both low-frequency absorption and audio playback.

[0025] In one optional embodiment, in a passenger vehicle usage environment, a subwoofer 1 is provided in the footwell, a subwoofer 1 is provided in the middle of each door, a midrange speaker 1 is provided at the bottom of the door, a tweeter 1 is provided below the window, a subwoofer 1 is provided on the side wall of the trunk, a midrange speaker 1 is provided on the center console, and several tweeters 1 and midrange speakers 1 are provided in the headrests and behind the rear seats. The noise reduction control circuits 2, each connected to one of the speakers 1, are integrated into the PCB board of the vehicle audio head unit and centrally controlled by the control chip Q3.

[0026] Specifically, the control chip Q3 controls the switching of the execution chip based on vehicle noise signals, vehicle system status signals, and vehicle system audio signals. For details of the control process, please refer to the description of the specific implementation method of the noise reduction method for this audio equipment below. The control chip Q3 intelligently switches based on the aforementioned multiple signal data, ensuring that the noise reduction function is activated only when necessary, avoiding conflicts with audio playback. For example, when the vehicle is idling, engine noise is significant, and the system automatically switches to noise reduction mode; while playing music, the system maintains audio mode to ensure sound quality.

[0027] In one specific implementation, vehicle noise signals are collected via an onboard microphone, an engine speed sensor, and a vehicle speed sensor. The control chip Q3 performs fusion processing on the multi-source signals. Specifically, the onboard microphone collects full-frequency sound pressure signals inside the vehicle, including all noise (engine, tire, wind noise, external environment) as well as possible mixed signals of music / human voices.

[0028] Engine speed and vehicle speed signals are obtained directly from the engine control unit and ABS / ESP system via the CAN bus. The engine is the primary source of low-frequency noise (especially order noise). Its fundamental frequency f_engine = (RPM / 60)Hz. For example, when the engine speed is 3000 RPM, its fundamental frequency is 50Hz, the second harmonic is 100Hz, the third is 150Hz, and so on. Additionally, tire noise is a major source of low-frequency noise, and tire noise is strongly correlated with vehicle speed. While the frequency range of tire noise is wide, the energy of its low-frequency components (such as <200Hz) increases significantly with vehicle speed. The magnitude of tire noise can be indirectly determined based on vehicle speed.

[0029] For example, in a vehicle idling scenario, specifically, with the vehicle speed at 0 and the engine speed at 800 RPM, the microphone measures a noise level of 65 dB, with the main peak at 26.7 Hz. The engine's fundamental frequency f... _engine =800 / 60=13.3Hz. The second-order frequency is 26.7Hz. At this time, the microphone displays that the main peak frequency matches the engine's second-order frequency. The control chip Q3 then controls the noise reduction control circuit 2, for example, the first noise reduction control circuit 2, to perform noise reduction processing based on the current main noise (engine second-order noise, intensity 65dB, main peak frequency 26.7Hz).

[0030] In a scenario of highway cruising, specifically at a vehicle speed of 100 km / h and an engine speed of 2500 RPM, the microphone measured a noise level of 72 dB, with the spectrum showing high energy in the 41.7 Hz and 120-300 Hz wideband. At this time, the engine's fundamental frequency f... _engine =41.7Hz, and according to the model, tire noise is expected to increase significantly around 150Hz at 100km / h. At this point, the peak value of 41.7Hz is identified as the engine's fundamental frequency noise, and the wideband energy of 120-300Hz is consistent with the vehicle speed model prediction and is determined to be the overall contribution of tire noise. The control chip Q3 comprehensively judges that the current noise is mixed, with an overall intensity of 72dB, and may identify two frequency bands that need noise reduction, thereby controlling the noise reduction control circuit 2 (first noise reduction control circuit 2 and second noise reduction control circuit 2) to perform noise reduction processing.

[0031] The control chip Q3 switches between the noise reduction control circuit 2 and the audio playback circuit 3 based on the driver's audio playback habits. This habit data is obtained through historical data learning (e.g., using machine learning algorithms to analyze daily audio playback time patterns) and stored in non-volatile memory. For example, if the system recognizes that the driver typically plays news between 8:00 and 8:30 AM, then even if the noise level is high during that time period, the audio playback circuit 3 will be activated first; at other times, the noise reduction mode will be switched based on the noise signal. This design ensures that the noise reduction function does not affect daily audio habits. Simultaneously, through habit learning, the system can predict user needs, reduce unnecessary mode switching, and improve the user experience.

[0032] This invention also provides a noise reduction method based on the aforementioned audio equipment, such as... Figure 4 As shown, this noise reduction method is implemented by executing a software algorithm through the control chip Q3. The specific steps are as follows: S1. Detect vehicle system status: Determine whether the vehicle system is on or off by reading the vehicle system's power signal.

[0033] S2. If the vehicle is turned off: control the first execution chip Q1 and the second execution chip Q2 to disconnect the audio playback circuit 3 from the speaker 1, and execute step S4.

[0034] S3. If the vehicle infotainment system is powered on: detect the vehicle infotainment system audio signal (sampled by ADC). If the audio signal strength is greater than the set threshold (audio signal strength ≥ 0.5V), control the execution chip (including the first execution chip Q1 and the second execution chip Q2) to disconnect the noise reduction control circuit 2 and keep the audio playback circuit 3 connected; if the strength is less than the set threshold, then execute step S4.

[0035] S4. Determine whether to perform noise reduction operation based on the collected noise signal: If the noise decibel value is greater than the set threshold (e.g., 60dB), then control the noise reduction control circuit 2 to connect with the speaker 1.

[0036] Specifically, the noise signal is collected through an onboard microphone, an engine speed sensor, and a vehicle speed sensor. For example, the microphone measures an in-vehicle noise intensity of 65dB, with a main peak frequency of 26.7Hz. The engine's second-order frequency is 26.7Hz. The control chip Q3 controls the first noise reduction control circuit 2 to connect to the speaker 1 based on the main noise (engine second-order noise, intensity 65dB, main peak frequency 26.7Hz) for noise reduction processing.

[0037] In one specific embodiment, when the noise reduction control circuit 2 includes several sub-control circuits, the control chip Q3 controls the matching noise reduction control sub-circuit to be turned on according to the main peak frequency of the noise. For example, if the main peak frequency is 80Hz, then the noise reduction control sub-circuit with a resonant frequency of 80Hz is selected to be turned on.

[0038] In one specific implementation, when the control chip Q3 determines that the current noise is mixed, the overall noise intensity is greater than the set threshold, and two frequency bands that need noise reduction may be identified, the first noise reduction control circuit 2 and the second noise reduction control circuit 2 are simultaneously connected to the speaker 1 to achieve noise reduction processing.

[0039] This noise reduction method achieves intelligent noise reduction in the vehicle by controlling the switching between the noise reduction control circuit 2 and the audio playback circuit 3. The speaker 1 acts as a passive acoustic load, and the resonant characteristics of the RLC circuit absorb low-frequency sound waves of a specific frequency, thus ensuring uninterrupted audio signal processing.

[0040] In one alternative implementation, such as Figure 5 As shown, the control chip Q3 identifies the driver's audio playback habits based on data from the vehicle driving habit database (e.g., by statistically analyzing historical data to determine daily fixed playback periods). If the real-time time reaches the scheduled audio playback time, the noise reduction control circuit 2 is disconnected, and the audio playback circuit 3 is connected. If the real-time time exceeds the set threshold for the scheduled audio playback time (e.g., 10 minutes), step S4 is executed again. By detecting the scheduled audio playback habits, both user habits and the real-time environment can be considered, avoiding equipment wear caused by frequent switching. For example, when the vehicle is idling, the system automatically absorbs low-frequency engine noise, reducing the in-vehicle noise to below 50dB; during the user's preferred playback period, the system seamlessly switches to audio mode, ensuring uninterrupted music playback.

[0041] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An automobile audio apparatus characterized by comprising: The application relates to a speaker and a noise reduction control circuit, an audio playing circuit and a control chip electrically connected with the speaker. The speaker comprises a driving unit, a positive electrode interface and a negative electrode interface. The noise reduction control circuit comprises a shunt resistor, a shunt capacitor and a shunt inductor connected in series. The audio playing circuit output end is connected with the positive electrode interface through the first execution chip, and the audio playing circuit backflow end is connected with the negative electrode interface through the second execution chip. The control chip controls the first execution chip and the second execution chip to synchronously switch, so that the audio playing circuit and the noise reduction control circuit are selectively connected. An operational amplifier is arranged between the shunt resistor and the shunt capacitor.

2. The car audio apparatus according to claim 1, wherein The noise reduction control circuit comprises at least two groups of noise reduction control sub-circuits with different parameters.

3. The car audio apparatus according to claim 1 or 2, wherein The control chip controls the first execution chip and the second execution chip according to a vehicle noise signal, a vehicle machine state signal and a vehicle machine audio signal, so that the audio playing circuit and the noise reduction control circuit are selectively connected.

4. The car audio apparatus according to claim 1, wherein The control chip controls the first execution chip and the second execution chip according to audio playing habit data of a driver, so that the audio playing circuit and the noise reduction control circuit are selectively connected.

5. The car audio apparatus according to claim 1, wherein The driving unit comprises a magnet, a voice coil, a paper cone, a dust cover and a T-shaped iron.

6. The car audio apparatus according to claim 1, wherein The vehicle noise signal is obtained by comprehensively judging one or more of a vehicle microphone, an engine speed signal and a vehicle speed signal.

7. The car audio apparatus according to claim 4, wherein The application comprises the following steps:

8. A method of reducing noise of an automobile audio device, characterized by, S1. Real-time detection of a vehicle machine state; S2. If the vehicle machine is turned off, the audio playing circuit and the speaker are disconnected, and step S4 is executed. S3. If the vehicle machine is turned on, a vehicle machine audio signal is detected, if the audio signal strength is greater than a set threshold value, the execution chip is controlled to disconnect the noise reduction control circuit, and the audio playing circuit is kept in a connected state; if the audio signal strength is less than the set threshold value, step 4 is executed. S4. According to the collected noise signal, it is judged whether noise reduction operation is performed, if the decibel value of the noise signal is greater than a set threshold value, the noise reduction control circuit and the speaker are connected. In step S4, the noise reduction control circuit matched with the detected noise main peak frequency is connected.

9. The noise reduction method of claim 8, wherein, According to the audio timing playing habit data of the driver and real-time time control, it is judged whether noise reduction operation is performed, if the real-time time reaches the audio timing playing time, the noise reduction control circuit is disconnected, and the audio playing circuit is connected.

10. The noise reduction method of claim 9, wherein, ​

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