Vehicle-mounted headrest audio system and method integrated with bone conduction and air conduction loudspeakers

Abstract

The invention relates to the technical field of automotive electronics and vehicle-mounted acoustics, and discloses a vehicle-mounted headrest audio system and method integrating a bone conduction loudspeaker and an air conduction loudspeaker, the system comprises a vehicle-mounted host and a headrest assembly, and a bone conduction loudspeaker module, an air conduction loudspeaker module, an intelligent sensing module and a control circuit module are integrated in the headrest assembly. The intelligent sensing module is used for collecting a passenger head state signal, and the control circuit module controls on-off of a power supply of the bone conduction loudspeaker module according to the signal. And meanwhile, the control circuit module receives a multi-channel audio input signal, performs matrix operation according to a preset routing strategy, distributes private signals such as navigation prompt and conversation to the bone conduction loudspeaker module, and distributes an entertainment audio signal to the air conduction loudspeaker module. Through double-path sound field separation and intelligent control, the problems of in-vehicle audio interference and privacy leakage are effectively solved, meanwhile, the perception of a driver to environment sound is guaranteed, and the driving safety and the system energy saving performance are improved.

Description

Technical Field

[0001] This invention relates to the fields of automotive electronics and vehicle acoustics, specifically to a vehicle headrest audio system and method integrating bone conduction and air conduction speakers. Background Technology

[0002] With the rapid popularization of smart cockpit technology, in-vehicle entertainment systems have become an important part of modern automobiles. Traditional in-vehicle audio systems mainly rely on air-conducted speakers placed in the doors, center console, or rear window sills to construct the sound field. This broadcast-style propagation method based on air conduction creates a unified, shared sound field in the small, enclosed space inside the car. In actual driving scenarios, this "shared" characteristic often leads to functional sound field interference. For example, when the driver needs to listen to navigation prompts or make a phone call, the audio signal will diffuse through the air throughout the cabin, which not only interrupts other passengers' rest or entertainment experiences but also fails to effectively protect the privacy of the call content.

[0003] To address in-car noise and privacy concerns, some drivers choose to wear in-ear or over-ear headphones. While this provides physical noise isolation and ensures call privacy, it also blocks the driver's ear canal, cutting off auditory interaction with the external environment. In complex traffic conditions, headphones make it difficult for drivers to hear horns, emergency vehicle sirens (such as ambulances and fire trucks), and unusual announcements from other passengers, posing a serious safety hazard. Furthermore, in high-noise environments such as at high speeds, drivers are often forced to increase the volume of their headphones or speakers to mask ambient noise, and prolonged exposure to high sound pressure levels can easily lead to auditory fatigue.

[0004] Current improvements include designs that integrate air-conducting speakers into the headrests to reduce interference with the entire vehicle by shortening the transmission distance. However, simple headrest air-conducting speakers cannot completely solve the sound leakage problem in open spaces, and privacy remains insufficient. Furthermore, existing in-vehicle headrest audio devices typically lack the ability to sense the actual usage status of occupants. As long as the vehicle audio system is on, the speakers operate continuously regardless of whether the occupant's head is resting on the headrest. For systems containing vibrating elements, this continuous operation not only generates ineffective mechanical vibration and noise, affecting cabin quietness, but also causes unnecessary energy consumption and accelerates the mechanical aging of the equipment. Therefore, how to effectively separate the private transmission and shared playback of in-vehicle audio without obstructing the ear canal to ensure driving safety, and how to achieve intelligent on-demand control of the system, are pressing technical problems that need to be solved in the field of automotive acoustics. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an in-vehicle headrest audio system that integrates bone conduction and air conduction speakers. It aims to solve problems such as navigation or call signal interference and privacy leaks caused by shared sound fields in existing in-vehicle audio systems, driving safety hazards caused by earphones blocking the ear canal and isolating ambient sounds, and ineffective vibrations and energy waste caused by the lack of intelligent perception of occupant status in existing headrest audio devices.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a vehicle headrest audio system and method integrating bone conduction and air conduction speakers, which aims to solve the problems of existing vehicle audio systems causing navigation or call signals to interfere with other passengers and privacy leaks due to shared sound fields, driving safety hazards caused by wearing headphones to block the ear canal and isolate ambient sounds, and ineffective vibration and energy waste caused by the lack of intelligent perception of the passenger's status in existing headrest audio devices.

[0007] The first aspect of the present invention provides an in-vehicle headrest audio system integrating bone conduction and air conduction speakers, including an in-vehicle host and an in-vehicle headrest assembly, wherein the in-vehicle host and the in-vehicle headrest assembly are communicatively connected.

[0008] The vehicle headrest assembly includes a headrest body, and a bone conduction speaker module, an air conduction speaker module, an intelligent sensing module, and a control circuit module integrated inside the headrest body.

[0009] The intelligent sensing module is located in the area where the headrest body contacts the occupant, and is used to collect sensor signals reflecting the occupant's head state and send the sensor signals to the control circuit module.

[0010] The control circuit module is connected to the vehicle host, the bone conduction speaker module, the air conduction speaker module, and the intelligent sensing module, respectively. The control circuit module receives multi-channel audio input signals from the vehicle host, controls the power supply of the bone conduction speaker module according to the sensor signals, and allocates the multi-channel audio input signals to generate bone conduction drive signals and air conduction drive signals according to a preset routing strategy.

[0011] The bone conduction speaker module is disposed on the front area of ​​the headrest body and is used to receive the bone conduction drive signal and convert it into mechanical vibration. The air conduction speaker module is disposed on the side or bottom area of ​​the headrest body and is used to receive the air conduction drive signal and convert it into airborne sound waves.

[0012] The bone conduction speaker module includes a vibrating plate, an elastic support structure, and a flexible pad. The vibrating plate, as an electromechanical transducer, generates the mechanical vibration. One end of the elastic support structure is connected to the inner wall of the headrest body's outer shell, and the other end is connected to the vibrating plate, providing physical support and decoupling the vibration. The flexible pad covers the outside of the vibrating plate and is located on the surface of the headrest body, contacting the back of the occupant's head or the area behind the ears to transmit the mechanical vibration.

[0013] The control circuit module has a preset trigger threshold. The control circuit module monitors the sensor signal in real time. When the sensor signal is greater than or equal to the trigger threshold, the activation state variable is set to an active state (e.g., logic 1), and the bone conduction speaker module is controlled to enter a working standby state. When the sensor signal is less than the trigger threshold, the activation state variable is set to an inactive state (e.g., logic 0), and the power supply to the bone conduction speaker module is cut off.

[0014] Optionally, the multi-channel audio input signal includes navigation prompt tone signal, telephone call audio signal, and entertainment audio signal. The control circuit module performs calculations on the multi-channel audio input signal based on the activation state variable and the routing matrix to generate an output vector. The output vector includes the bone conduction drive signal and the air conduction drive signal. When the activation state variable is invalid, the bone conduction drive signal is forced to zero.

[0015] In one specific implementation, the routing strategy includes a driver standard mode. In the driver standard mode, the routing matrix is ​​configured to route the navigation prompt tone signal and the telephone call audio signal to the bone conduction drive signal, and to route the entertainment audio signal to the air conduction drive signal, thereby achieving sound field separation by transmitting privacy-related audio information through the skull and transmitting shared entertainment information through the air.

[0016] Optionally, the routing strategy further includes a user-defined mode, in which the control circuit module, in response to the user's configuration command, modifies the coefficient values ​​of the routing matrix to route the entertainment audio signal to the bone conduction drive signal, so that the entertainment audio signal is played only through the bone conduction speaker module.

[0017] In the specific hardware configuration, the intelligent sensing module includes a piezoelectric sensor or a capacitive proximity sensor. The pressure sensor or the proximity sensor is configured to detect whether the occupant's head is resting on the headrest body. When the occupant's head is detected, the control circuit module activates the bone conduction speaker module; when the occupant's head is detected to be removed, the control circuit module deactivates the bone conduction speaker module to achieve system energy saving.

[0018] Preferably, the flexible pad is made of a material whose acoustic impedance matches that of human skin, in order to reduce the reflection loss of the mechanical vibration at the contact interface.

[0019] In addition, the control circuit module establishes a bidirectional data connection with the vehicle host via an A2B digital audio bus or a wireless transmission protocol. The bidirectional data connection is used to transmit the multi-channel audio input signals and the control commands for the routing strategy.

[0020] A second aspect of the present invention provides an audio method for a vehicle headrest integrating bone conduction and air conduction speakers, comprising the following steps:

[0021] Step S100: The sensor signal is collected by the intelligent sensing module, and it is determined whether the sensor signal meets the trigger threshold condition. If it does, the activation state variable is set to the valid state and the bone conduction speaker module is activated. If it does not meet the threshold condition, the activation state variable is set to the invalid state.

[0022] Step S200: The control circuit module receives the multi-channel audio input signal and parses out the navigation prompt tone signal, telephone call audio signal and entertainment audio signal;

[0023] Step S300: The control circuit module determines the routing matrix according to the current routing mode configuration, and performs matrix operation on the input vector composed of the navigation prompt tone signal, the telephone call audio signal and the entertainment audio signal with the routing matrix, and generates an output vector by combining the activation state variable; the output vector includes the bone conduction drive signal and the air conduction drive signal;

[0024] Step S400: The bone conduction speaker module generates mechanical vibration according to the bone conduction drive signal in the output vector and transmits it to the occupant's skull via a flexible pad; the air conduction speaker module generates airborne sound waves according to the air conduction drive signal in the output vector and radiates them into the free space inside the vehicle.

[0025] This invention provides a vehicle headrest audio system integrating bone conduction and air conduction speakers. It has the following advantages:

[0026] 1. This invention integrates both bone conduction and air conduction acoustic pathways within the headrest and utilizes a control circuit module to execute a scenario-based routing strategy. This strategy allocates private signals such as navigation prompts and telephone calls to the bone conduction speaker module, while entertainment audio signals are allocated to the air conduction speaker module. This differentiated transmission method allows sensitive information to be transmitted directly to the auditory nerve via the skull, avoiding sound diffusion in the air and solving the problems of driver interference with passenger rest and privacy breaches. Simultaneously, because bone conduction does not require blocking the ear canal, the driver can still perceive external horns, alarms, and conversations among passengers while listening to audio, effectively avoiding driving safety hazards caused by auditory blockage.

[0027] 2. This invention incorporates an intelligent sensing module (such as a piezoelectric or capacitive sensor) in the contact area between the headrest and the occupant. Combined with threshold judgment logic within the control circuit module, this allows for real-time monitoring of whether the occupant's head is in a supported position. When the head is detected to be off the headrest, the system automatically cuts off the power to the bone conduction speaker module, invalidating the activated state variable. This effectively prevents the bone conduction unit from generating ineffective vibrations and mechanical noise when unused, solving the energy waste problem and extending the lifespan of the vibration components.

[0028] 3. The bone conduction speaker module of this invention employs an elastic support structure connected to the headrest shell, and a flexible pad with acoustic impedance matching human skin covers the outside of the vibrating plate. The elastic support structure provides physical support and achieves vibration decoupling, preventing resonance noise from the headrest shell caused by the vibrating plate operating at high frequencies; the flexible pad with specific acoustic impedance characteristics reduces the reflection loss of mechanical waves at the contact interface, ensuring that audio energy is efficiently transmitted to the skull, improving sound clarity while avoiding the discomfort caused by hard contact, and enhancing the user's long-term use experience. Attached Figure Description

[0029] Figure 1 This is a system framework diagram of the present invention;

[0030] Figure 2 This is a schematic diagram of the method flow of the present invention.

[0031] 100. Vehicle host unit; 200. Vehicle headrest assembly; 210. Headrest body; 220. Bone conduction speaker module; 230. Air conduction speaker module; 240. Intelligent sensing module; 250. Control circuit module. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0033] See attached document Figure 1 This invention provides an integrated bone conduction and air conduction speaker system for vehicle headrests, mainly comprising a vehicle host 100 and a vehicle headrest assembly 200. The vehicle host 100 serves as the core signal source and interactive terminal of the system, used to generate and send audio signals and control commands. The vehicle headrest assembly 200 is physically installed above the back of the car seat and includes a headrest body 210, a bone conduction speaker module 220, an air conduction speaker module 230, a smart sensor module 240, and a control circuit module 250. The vehicle host 100 establishes a bidirectional data connection with the control circuit module 250 inside the vehicle headrest assembly 200 via a wired harness or wireless communication protocol. The wireless transmission protocols include, but are not limited to, Bluetooth (especially Low Energy Audio LE Audio), Wi-Fi (such as Wi-Fi Direct point-to-point connection), Ultra Wideband (UWB) technology, or proprietary 2.4G / 5.8G low-latency radio frequency transmission protocols. These protocols ensure low latency and high fidelity of audio data during transmission.

[0034] The physical structure layout of the vehicle headrest assembly 200 is as follows: The bone conduction speaker module 220 is located in the front area of ​​the headrest body 210, which is spatially positioned to correspond to the back of the occupant's head or the area behind the ear. The bone conduction speaker module 220 includes a vibrating plate, an elastic support structure, and a flexible pad. The vibrating plate, as the core component of electromechanical energy conversion, is used to generate mechanical vibration; the elastic support structure connects the vibrating plate to the inner wall of the headrest body 210, providing the necessary stiffness and damping characteristics for the vibration system; to adapt to different vibration frequency response requirements, the elastic support structure can specifically adopt a metal coil spring, a corrugated metal spring, a rubber damping column, a silicone suspension bracket, or a magnetic levitation support. In this embodiment, a silicone suspension bracket with an adjustable stiffness coefficient is preferably used, combined with a specific damping ratio, to effectively decouple low-frequency mechanical vibrations below 500Hz and prevent resonance noise from the headrest shell.

[0035] A flexible pad covers the surface of the headrest body 210 that contacts the occupant's head, and a bone conduction speaker module 220 is located below this flexible pad. An air conduction speaker module 230 is disposed on the side or lower region of the headrest body 210 and is configured to radiate sound waves into the free space inside the vehicle. A smart sensing module 240 is embedded in the front contact area of ​​the headrest body 210 and is selected from pressure sensors or proximity sensors to detect the presence of the occupant's head.

[0036] To clarify the physical operating characteristics of the bone conduction speaker module 220, a dynamic transmission model of the module is established. When driven by an input electrical signal, the vibrating plate undergoes displacement. The motion of this vibration system follows a second-order differential equation:

[0037] ;

[0038] in, This represents the displacement of the vibrating plate relative to its equilibrium position. This represents the equivalent mass of the vibrating component. This represents the damping coefficient of the elastically supported structure. This represents the stiffness coefficient of the elastically supported structure. This represents the driving force obtained by converting electrical signals.

[0039] Flexible pads have specific vibration coupling efficiency This results in the effective vibration velocity transmitted to the occupant's skull. satisfy This structural design ensures that vibrational energy can pass through the flexible padding and couple to the human body, while the elastic support structure isolates harmful shell resonance.

[0040] The control circuit module 250 is integrated inside the headrest body 210, and it receives sensing signals from the smart sensing module 240 and audio input signals from the vehicle host 100. The control circuit module 250 is configured to perform signal power amplification, analog-to-digital / digital-to-analog conversion, and logic-based signal routing switching.

[0041] In terms of specific hardware implementation, the control circuit module 250 can employ one or a combination of digital signal processors (DSPs), microcontrollers (MCUs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or automotive system-on-chips (SoCs). The control circuit module 250 also integrates a multi-channel audio codec and a Class-D power amplifier (Class-D AMP) circuit to drive bone conduction and air conduction units with different load impedances.

[0042] See attached document Figure 2 This invention provides an audio method for a vehicle headrest that integrates bone conduction and air conduction speakers, the method comprising:

[0043] Step S100: Occupant status perception and system activation; Step S200: Audio signal acquisition and type recognition; Step S300: Execution of scene-based intelligent routing strategy; Step S400: Transduction and output of mixed audio signals.

[0044] In step S100, the control circuit module 250 acquires the sensor signals output by the intelligent sensing module 240 in real time. The system presets a trigger threshold. The control circuit module 250 determines the system's activation state variable based on the comparison results. ;

[0045] when At that time, it was determined that the passenger's head was resting on the headrest. When set to 1, the control circuit module 250 supplies power to the bone conduction speaker module 220, putting it into a working standby state; when At that time, it was determined that the occupant's head had left the berth. When the value is set to 0, the system cuts off the power supply to the bone conduction speaker module 220 to save energy.

[0046] In step S200, the control circuit module 250 receives a multi-channel audio input signal from the vehicle-mounted head unit 100. This input signal is defined as an input vector. It contains various types of audio components. Input vector Represented as:

[0047] ;

[0048] in, This represents a navigation prompt tone signal. Represents the audio signal of a telephone call. Represents entertainment audio signals such as music or video. This represents the vector transpose. The vehicle-mounted host 100 sends audio data along with a signal type identifier, which the control circuit module 250 uses to parse the aforementioned components.

[0049] In step S300, the control circuit module 250 determines the current activation state variable based on the current activation state variable. And a preset or user-defined routing strategy, to construct the output signal vector. Output signal vector Includes drive signals transmitted to the bone conduction speaker module 220 and the drive signal transmitted to the air conduction speaker module 230 ,Right now This mapping relationship is achieved through the routing matrix. The implementation and operation logic are as follows:

[0050] ;

[0051] in This is the default output state when the head leaves (typically only air conduction output is retained). In the default driving mode, the routing matrix... Configure as default matrix :

[0052] ;

[0053] The result of this matrix operation makes Include and The amount, and Only contains The amount.

[0054] This enables the physical routing of private, sensitive information to the bone conduction pathway, while shared entertainment information is routed to the air conduction pathway. When the system receives a switching command from a user (e.g., a passenger), the routing matrix... Reconstructed into a custom matrix ,Will Component redirection to To achieve a private entertainment mode.

[0055] In step S400, the bone conduction speaker module 220 and the air conduction speaker module 230 respond to the drive signal respectively. and Work. The bone conduction speaker module 220 will... This is converted into mechanical vibrations, which are transmitted to the occupant's skull via a flexible pad; the air-conducting speaker module 230 will... It is converted into airborne sound waves and radiated into the car. At this time, if Passengers can simultaneously perceive private audio from the bone conduction pathway and shared audio (or ambient sound) from the air conduction pathway. The two do not interfere with each other in terms of auditory perception, thus achieving a safe in-vehicle auditory experience with separation of public and private audio.

[0056] Step S100 is executed by the control circuit module 250 in conjunction with the intelligent sensing module 240, aiming to achieve high-precision triggering and energy management of bone conduction function. To achieve this objective, step S100 further includes sub-steps S101 to S103.

[0057] In sub-step S101, the system performs physical acquisition and preprocessing of sensor signals. The intelligent sensing module 240 is configured to monitor changes in physical parameters of the front contact area of ​​the headrest body 210 in real time. In one specific embodiment, the intelligent sensing module 240 employs a piezoelectric or piezoresistive thin-film pressure sensor array, which is laid between the flexible padding and the bone conduction speaker module 220. When the occupant's head rests against the sensor array, the resistance value changes and is converted into an analog voltage signal via a Wheatstone bridge circuit.

[0058] In another embodiment, the intelligent sensing module 240 employs a capacitive proximity sensor, utilizing the change in capacitance caused by the occupant's head as a dielectric to generate a detection signal. This analog signal is sampled by an analog-to-digital converter (ADC) within the control circuit module 250 to generate a digitized raw sensor signal. The specific signal conditioning circuit design for the sensor, such as a low-pass filter circuit to filter out high-frequency electromagnetic interference or vehicle vibration noise, falls within the scope of circuit design well-known to those skilled in the art and will not be elaborated upon here.

[0059] In sub-step S102, the control circuit module 250 performs logical judgment based on the collected signals to determine the activation state variable. The control circuit module 250 reads the preprocessed sensor signal strength value. and compare it with the preset trigger threshold. Compare them.

[0060] To prevent frequent system malfunctions caused by momentary slight separation between the head and headrest due to bumps during vehicle operation, the control circuit module 250 executes the aforementioned decision logic (i.e., when...). When a head is determined to exist, a time window de-jitter algorithm or Schmitt trigger logic is introduced. Specifically, only when... Continuously maintain at the threshold within the predetermined time window Only after the above conditions are met will the system confirm the judgment result and activate the state variable. Set to 1; conversely, when the signal remains below the threshold or reset threshold, Set to 0. The logical operation here directly determines the value in the aforementioned formula. The value of affects the result of subsequent routing matrix calculations.

[0061] In sub-step S103, the control circuit module 250 determines the activation state variable. Perform power gating operations on the bone conduction speaker module 220. The control circuit module 250 integrates a power management unit (PMU) or a controlled electronic switching device (such as a MOSFET).

[0062] when When set to 1, the control circuit module 250 outputs a high-level control signal to turn on the electronic switch, which transmits the energy of the vehicle power supply to the drive amplifier circuit of the bone conduction speaker module 220, so that it switches from sleep mode to working standby mode and is ready to receive audio signals.

[0063] when When set to 0, the control signal flips, cutting off the power supply circuit to the bone conduction pathway. Through this hardware-level physical on / off control, the system can completely eliminate the static power consumption of the bone conduction unit when no occupant is leaning against it, achieving energy-saving control. At the same time, this step ensures that bone conduction vibration is only generated when the head is in close coupling with the headrest, avoiding abnormal noises that may occur when the vibrating plate vibrates under no-load conditions in a non-contact state.

[0064] After the system confirms that it is in standby or working state, the control circuit module 250 executes step S200 to complete the parsing and standardization of the input signal source. This step is further refined into sub-steps S201 to S202.

[0065] In sub-step S201, the control circuit module 250 establishes a data transmission link with the vehicle host 100 through a physical communication interface. This communication interface is configured to support multi-channel audio data transmission and control command interaction.

[0066] In one specific embodiment, the vehicle-mounted host 100 and the control circuit module 250 are digitally connected using an Automotive Audio Bus (A2B) or Ethernet Audio-Video Bridge (Ethernet AVB) protocol. The vehicle-mounted host 100 sends audio data streams from different sources to the control circuit module 250 in the form of time-division multiplexing (TDM) or packet encapsulation.

[0067] In another embodiment, the connection method employs multiple analog audio inputs in conjunction with a Controller Area Network (CAN) bus, where the analog lines transmit waveform data and the CAN bus transmits corresponding source status flags. The specific physical layer implementation of the aforementioned bus protocol and the handshake communication process fall within the scope of communication technologies well-known to those skilled in the art, and will not be elaborated upon here.

[0068] In sub-step S202, the control circuit module 250 demultiplexes and identifies the type of the received mixed data stream to construct the input audio signal vector defined in the aforementioned system architecture. To achieve intelligent routing, the control circuit module 250 needs to identify the semantic attributes of each audio stream. Specifically, when sending audio data, the vehicle host 100 embeds a source type identifier (Source ID) in the data packet header or sends metadata through the control channel. These identifiers are used to indicate whether the current audio stream belongs to interactive audio with privacy attributes or entertainment audio with public attributes.

[0069] The digital signal processor (DSP) inside the control circuit module 250 parses the above identifier and maps the unpacked audio stream to the input audio signal vector. In the corresponding components.

[0070] As defined in the aforementioned system architecture section The control circuit module 250 performs the following specific mapping operations:

[0071] When a notification tone data stream from the in-vehicle navigation software is detected, it is assigned to a component. ;

[0072] When a downlink voice data stream from the Bluetooth Hands-Free Protocol (HFP) or the vehicle phone module is detected, it is assigned to a component. ;

[0073] When a broadband audio data stream from a multimedia player, radio, or online streaming media is detected, it is assigned to a component. .

[0074] Through this classification mapping, the control circuit module 250 transforms the mixed bit stream transmitted at the physical layer into a logical vector that the system algorithm can process, providing standardized input variables for subsequent intelligent routing based on matrix operations.

[0075] If a certain type of audio source is not currently active (e.g., no navigation instructions), the corresponding vector component is set to zero.

[0076] After classifying and standardizing the audio signals, the control circuit module 250 executes step S300, using its internal digital signal processor (DSP) to perform path allocation and mixing of the input signals. The core of this step lies in dynamically configuring the destination of the audio stream through matrix operations, specifically including sub-steps S301 to S303.

[0077] In sub-step S301, the control circuit module 250 determines the current routing mode configuration. The control circuit module 250 reads the status register in the system memory, the value of which is controlled by control commands from the vehicle host 100. The system is defaulted to the driver standard mode, which aims to balance the driver's need for private communication with the shared entertainment needs of in-vehicle passengers. When a user (e.g., a front passenger or rear passenger) operates the vehicle's central control screen via touchscreen or inputs voice control commands via microphone, the vehicle host 100 generates a routing switching command and sends it to the control circuit module 250, updating the system status to either the user-defined mode or the privacy entertainment mode.

[0078] In sub-step S302, the control circuit module 250 constructs or invokes the corresponding routing matrix based on the determined routing mode. Routing matrix It is a dimension The logic coefficient matrix has row vectors corresponding to the bone conduction output channel and the air conduction output channel, respectively, and column vectors corresponding to the navigation, call, and entertainment input sources, respectively.

[0079] When the system is in driver standard mode, the control circuit module 250 calls the default matrix. As described in the aforementioned system architecture, The first row vector is configured as The second row vector is configured as This configuration allows the DSP to process the navigation signal components. Telephone signal components The coefficient is set to 1 and mapped to the bone conduction channel to achieve digital mixing; at the same time, the entertainment signal component is... The coefficient is set to 1 and mapped to the air conduction channel. For elements in the matrix with a coefficient of 0, the DSP performs mute processing.

[0080] Through this logical isolation at the signal processing level, the system ensures that sensitive audio data streams are not played through the air-conducting speaker module 230, thereby physically blocking the diffusion of sound into the vehicle interior.

[0081] When the system switches to a user-defined mode (e.g., when a passenger wishes to listen to media audio independently via bone conduction), the control circuit module 250 reconstructs the routing matrix into a custom matrix. In this scenario, The first row vector is adjusted to (Or configure to retain call functionality as needed) The second row vector is adjusted to .

[0082] This configuration enables the entertainment signal components The routing path changes, switching from the air conduction channel to the bone conduction channel, and the air conduction speaker module 230 stops radiating sound waves due to zero input, realizing the passenger's personal private listening space.

[0083] In sub-step S303, the control circuit module 250 performs the final output vector calculation. The DSP references the activation state variable determined in the aforementioned step S100. and the input vector obtained in step S200 According to the formula Perform real-time convolution operations.

[0084] In this operational logic, the state variable is activated. It acts as a global gating factor on the output of the routing matrix. If A value of 0 (i.e., no header detected) is used regardless of the routing matrix. How to configure and calculate the output vector Bone conduction driving signals It will be forcibly reset to zero. If If the value is 1, the calculation result is valid, and the generated output vector is... It includes the specific waveform data after routing. This calculation process is executed cyclically within the DSP's clock cycle, ensuring low latency of the audio output relative to the input signal, thereby guaranteeing the real-time performance of navigation commands and the smoothness of calls.

[0085] After the control circuit module 250 completes the intelligent routing and power amplification of the signal, the system enters step S400, which converts the electrical signal into acoustic energy perceptible to the human ear through two parallel physical paths. This step is specifically implemented through sub-steps S401 and S402, which correspond to the construction of the private communication channel and the shared entertainment channel, respectively.

[0086] In sub-step S401, the bone conduction speaker module 220 performs the energy conversion process from electrical signals to mechanical vibrations and then to conduction through biological tissue. The bone conduction speaker module 220 receives drive signals from the control circuit module 250. The electromechanical transducers inside this module (such as moving-coil or piezoelectric transducers) first convert electrical energy into mechanical driving force. According to the linear electromechanical coupling model, the relationship between the driving force and the input voltage is as follows: ,in This is the electromechanical coupling coefficient, which depends on physical parameters such as the magnetic flux density and the number of turns of the voice coil in the transducer's magnetic circuit system.

[0087] The driving force generated The force acts on the vibrating plate, causing it to reciprocate. The motion characteristics of the vibrating plate are controlled by its physical support boundary conditions, i.e., the elastic support structure. Here, the vibration dynamics model established in the aforementioned system architecture is cited, and the displacement response of the vibration system is discussed. Follows differential equations This will not be elaborated upon here.

[0088] In this embodiment, the stiffness coefficient of the elastic support structure With damping coefficient Through specific tuning, its natural frequency falls within the human voice frequency range (e.g., 300Hz to 3400Hz) to maximize the response efficiency of navigation voice and telephone voice. At the same time, the elastic support structure physically decouples the vibrating plate from the rigid shell of the headrest body 210, preventing vibration energy from spreading to other non-contact areas of the headrest, thereby avoiding sound leakage caused by shell resonance.

[0089] Subsequently, the vibrational energy is transmitted to the occupant's skull via a flexible padding covering the headrest surface. This flexible padding is made of a viscoelastic material with specific acoustic impedance characteristics (such as high-density memory foam or a silicone composite), configured to provide head support while also serving as a vibration transmission medium. The vibration coupling efficiency of the flexible padding is defined as... ( The effective vibration velocity that ultimately acts on the occupant's skull is then determined. for The coupling efficiency Related to the dynamic modulus and thickness of the material, this embodiment optimizes the liner thickness and material density to ensure... While clearly stimulating inner ear hearing, it maintains the cushioning performance of the headrest as a passive safety component. The sound received by the occupant through this path bypasses the external auditory canal and eardrum, thus not affecting their reception of environmental warning sounds via air conduction.

[0090] In sub-step S402, the air-conducting loudspeaker module 230 performs the radiation process from the electrical signal to airborne sound waves. The air-conducting loudspeaker module 230 receives the drive signal. Its internal diaphragm drives the air medium to generate rarefaction waves. This process is described in the frequency domain by a sound field radiation model, i.e. ,in This refers to the sound pressure level at a point within the car's sound field. It is a system transfer function that includes the speaker's electroacoustic parameters and the acoustic transmission characteristics within the vehicle.

[0091] Since the air-conducting speaker module 230 is located on the side or under the headrest, the sound waves it radiates diffuse into the free space inside the vehicle, creating an open sound field environment that can be shared by multiple occupants.

[0092] Through the concurrent or independent execution of the aforementioned sub-steps S401 and S402 (depending on the configuration of the routing matrix), the system achieves the physical coexistence and independent control of the bone conduction private transmission path and the air conduction shared transmission path. At that time, the driver can sense through the skull. The private information carried is received simultaneously through both ears. The inclusion of background music and external ambient sounds enables the technical effects of this invention to be achieved at the physical transduction level.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vehicle headrest audio system integrating bone conduction and air conduction speakers, characterized in that, The device includes an in-vehicle host and an in-vehicle headrest assembly, wherein the in-vehicle host is communicatively connected to the in-vehicle headrest assembly; the in-vehicle headrest assembly includes a headrest body, and a bone conduction speaker module, an air conduction speaker module, an intelligent sensing module, and a control circuit module integrated inside the headrest body; The intelligent sensing module is located in the area where the headrest body contacts the occupant, and is used to collect sensor signals reflecting the occupant's head state and send the sensor signals to the control circuit module. The control circuit module is connected to the vehicle host, the bone conduction speaker module, the air conduction speaker module and the intelligent sensing module respectively. The control circuit module receives multi-channel audio input signals from the vehicle host, controls the power supply of the bone conduction speaker module according to the sensor signals, and allocates the multi-channel audio input signals to generate bone conduction drive signals and air conduction drive signals according to a preset routing strategy. The bone conduction speaker module is disposed in the front area of ​​the headrest body and is used to receive the bone conduction drive signal and convert it into mechanical vibration; The air-conducting speaker module is disposed on the side or bottom of the headrest body and is used to receive the air-conducting drive signal and convert it into air sound waves.

2. The in-vehicle headrest audio system integrating bone conduction and air conduction speakers according to claim 1, characterized in that, The bone conduction speaker module includes a vibrating plate, an elastic support structure, and a flexible pad. The vibrating plate serves as an electromechanical energy transducer, used to generate the mechanical vibration; One end of the elastic support structure is connected to the inner wall of the outer shell of the headrest body, and the other end is connected to the vibration plate, which is used to provide physical support for the vibration plate and realize vibration decoupling; The flexible pad covers the outside of the vibrating plate and is located on the surface of the headrest body, for contacting the back of the occupant's head or the area behind the ears and transmitting the mechanical vibration.

3. The in-vehicle headrest audio system integrating bone conduction and air conduction speakers according to claim 1, characterized in that, The control circuit module has a preset trigger threshold. The control circuit module monitors the sensor signal in real time. When the sensor signal is greater than or equal to the trigger threshold, the activation state variable is set to 1, and the bone conduction speaker module is controlled to enter the working standby state. When the sensor signal is less than the trigger threshold, the activation state variable is set to 0, and the power supply of the bone conduction speaker module is cut off.

4. The in-vehicle headrest audio system integrating bone conduction and air conduction speakers according to claim 3, characterized in that, The multi-channel audio input signals include navigation prompt signals, telephone call audio signals, and entertainment audio signals; The control circuit module performs calculations on the multi-channel audio input signal based on the activation state variable and the routing matrix to generate an output vector; The output vector includes the bone conduction drive signal and the air conduction drive signal; when the activation state variable is 0, the bone conduction drive signal is forced to zero.

5. A vehicle headrest audio system integrating bone conduction and air conduction speakers according to claim 4, characterized in that, The routing strategy includes a standard driver mode; In the standard driver mode, the routing matrix is ​​configured to route the navigation prompt tone signal and the telephone call audio signal to the bone conduction drive signal, and to route the entertainment audio signal to the air conduction drive signal, thereby achieving sound field separation where private information is transmitted through the skull and shared information is transmitted through the air.

6. A vehicle headrest audio system integrating bone conduction and air conduction speakers according to claim 5, characterized in that, The routing strategy also includes user-defined modes; In the user-defined mode, the control circuit module responds to the user's configuration command by modifying the coefficient values ​​of the routing matrix to route the entertainment audio signal to the bone conduction drive signal, so that the entertainment audio signal is played only through the bone conduction speaker module.

7. A vehicle headrest audio system integrating bone conduction and air conduction speakers according to claim 1, characterized in that, The intelligent sensing module includes a piezoelectric sensor or a capacitive proximity sensor. The pressure sensor or the proximity sensor is configured to detect whether the occupant's head is resting on the headrest body; when the occupant's head is detected, the control circuit module activates the bone conduction speaker module; when the occupant's head is detected to be moving away, the control circuit module deactivates the bone conduction speaker module and saves energy.

8. A vehicle headrest audio system integrating bone conduction and air conduction speakers according to claim 2, characterized in that, The flexible pad is made of a material whose acoustic impedance matches that of human skin, in order to reduce the reflection loss of the mechanical vibration at the contact interface.

9. A vehicle headrest audio system integrating bone conduction and air conduction speakers according to claim 1, characterized in that, The control circuit module establishes a bidirectional data connection with the vehicle host via an A2B digital audio bus or a wireless transmission protocol. The bidirectional data connection is used to transmit the multi-channel audio input signals and the control commands for the routing strategy.

10. An audio method for a vehicle headrest integrating bone conduction and air conduction speakers, characterized in that, An in-vehicle headrest audio system integrating bone conduction and air conduction speakers as described in any one of claims 1-9, comprising: Step S100: Collect the sensor signal through the intelligent sensing module, determine whether the sensor signal meets the trigger threshold condition. If it meets the threshold condition, set the activation state variable to 1 and activate the bone conduction speaker module. If it does not meet the threshold condition, set the activation state variable to 0. Step S200: The control circuit module receives the multi-channel audio input signal and parses out the navigation prompt tone signal, telephone call audio signal and entertainment audio signal; Step S300: The control circuit module determines the routing matrix according to the current routing mode configuration, and performs matrix operation on the input vector composed of the navigation prompt tone signal, the telephone call audio signal and the entertainment audio signal with the routing matrix, and generates an output vector by combining the activation state variable; the output vector includes the bone conduction drive signal and the air conduction drive signal; Step S400: The bone conduction speaker module generates mechanical vibration according to the bone conduction drive signal in the output vector and transmits it to the occupant's skull via a flexible pad; the air conduction speaker module generates airborne sound waves according to the air conduction drive signal in the output vector and radiates them into the free space inside the vehicle.

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