Energy-saving directional loudspeaker system capable of controlling angle range of sound field

Abstract

The invention discloses a directional loudspeaker system capable of controlling a sound field angle range and having a dynamic energy-saving capability, and belongs to the crossing field of acoustic engineering and electronic engineering. The directional loudspeaker system comprises an ultrasonic transducer array, and the direction and range of a sound field beam are flexibly regulated and controlled through a channel independent phase control technology. Meanwhile, the system adopts a random sampling integral decision algorithm to monitor the audio signal strength and dynamically start and stop the ultrasonic carrier output, so that the standby and low-load energy consumption is remarkably reduced. According to the invention, hardware design is optimized, sound quality, efficiency and cost are considered, and the problems of inflexible sound field control, high energy consumption and complex system in the prior art are effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of acoustic engineering and electronic engineering technology, in particular to a directional loudspeaker capable of accurately adjusting the angle range of sound field through multi-channel phase control, ultrasonic modulation and dynamic energy-saving algorithm, and is especially suitable for vehicle audio, smart home and public broadcasting scenarios. BACKGROUND

[0002] In the current directional loudspeaker technology, the scheme based on ultrasonic modulation and sound field control is widely used in vehicle audio, smart home and public broadcasting fields due to its ability to realize directional sound propagation and reduce environmental interference. The existing technology mainly realizes directional sound through acoustic compensation, mechanical adjustment or simple logic control, but still faces significant challenges in dynamic adjustment of sound field angle, system cost and sound quality optimization.

[0003] The current mainstream implementation methods include:

[0004] 1. Vehicle sound compensation scheme: by dividing the in-vehicle audio playback area, using directional loudspeakers to project mid-high frequency sound to a specific area, and combining with a sound compensator to supplement low frequency signals. This method improves sound privacy, but the sound field angle range is fixed and lacks dynamic adjustment capability, making it difficult to flexibly control the sound beam coverage range according to environmental changes.

[0005] 2. Intelligent control scheme based on distance detection: by detecting the distance threshold between the user and the device to control the switch of the loudspeaker. This scheme simplifies the operation process, but only realizes the switching function and does not involve real-time adjustment of sound field angle, beam shape and other parameters, making it difficult to meet the fine needs of complex scenarios.

[0006] 3. Adjustable elevation scheme: uses a motor to drive the elevation adjustment of the loudspeaker, combined with a feedback mechanism to optimize sound coverage. However, the mechanical structure relies on high-precision motors and sensors, resulting in a significant increase in system complexity and cost, and the dynamic response speed is limited.

[0007] The above schemes have the following common problems:

[0008] · Sound field angle control is rigid: existing technologies (such as vehicle compensation schemes) achieve sound field control through fixed zoning or mechanical adjustment, and cannot dynamically change the sound beam propagation direction (such as 0°-90° range adjustment) through electronic phase control, limiting the adaptability of the scene.

[0009] · Lack of intelligence and energy efficiency: the distance detection-based scheme only supports simple switching logic and does not integrate sound field parameter adaptive algorithms, and the standby power consumption is relatively high (generally > 2W), making it difficult to achieve energy-saving optimization.

[0010] System complexity and signal distortion: Some solutions (such as elevation adjustable design) rely on complex hardware architecture (multi-speaker cooperation, high-cost motor), leading to rising manufacturing costs; at the same time, the non-linear distortion problem (such as harmonic interference) in the ultrasonic modulation process reduces the stability of the sound quality.

[0011] Therefore, in view of the problems of insufficient dynamic adjustment of sound field angle, high system complexity and sound quality defects in the prior art, there is an urgent need for a directional loudspeaker scheme that can realize high-precision phase control, low power consumption and cost optimization to promote practical breakthroughs in diversified application scenarios. SUMMARY

[0012] The present application aims to solve the problems of insufficient dynamic adjustment of sound field angle, high system complexity and cost, high overall energy consumption, and defects in demodulated sound quality in the prior art, and provides a directional loudspeaker system that can realize accurate and dynamic control of sound field angle and has high energy efficiency.

[0013] To achieve the above purpose, the technical scheme adopted by the present application is:

[0014] The present application provides a directional loudspeaker that can control the sound field angle range, characterized by the following steps:

[0015] S1, the input audio signal is combined, biased and impedance matched by the audio signal preprocessing module to provide a single-polarity audio signal with a preset DC bias for the subsequent modules;

[0016] S2, the signal from the audio signal preprocessing module is processed by the multi-channel ultrasonic modulator, the counter and comparator generate independent ultrasonic pulse signals for each channel with predetermined modulation parameters, and the phase of each channel signal is adjusted independently according to the instruction;

[0017] S3, the independent modulation signals of each channel are power amplified by the ultrasonic signal power amplifier array to provide sufficient driving power for the corresponding units of the ultrasonic transducer array;

[0018] S4, the corresponding electrical signals from the power amplifier array are converted into ultrasonic signals by the ultrasonic transducer array, and the ultrasonic signals generated by the transducer units are based on the independent phase adjustment of each channel to interfere and superimpose in space to form a directional sound field, realizing the spatial distribution control of sound;

[0019] S5, collecting the single-polarity audio signal from the audio signal pre-processing module at a preset frequency through an analog-to-digital converter (ADC) in the control module; transmitting the ADC sampling data to a storage area through a direct memory access (DMA) controller; initializing and configuring each hardware resource of the system through a core processor, setting the ADC sampling parameters, the ultrasonic wave modulation parameters of each channel, and the phase parameters required by the phase-shifting module, and executing a dynamic carrier control algorithm to dynamically control the start and stop of the ultrasonic wave carrier signal in the multi-channel ultrasonic wave modulator according to the audio signal intensity, so as to turn off the carrier when there is no effective audio output or the audio output is extremely weak, and realize the switching between the working mode and the energy-saving standby mode.

[0020] Further, the step S1 comprises the following steps:

[0021] The audio input interface receives the audio signal from the outside, and combines the stereo signal into a single-channel signal through the combining circuit of the left and right channels. The synthesized signal passes through the bias network to add a direct current component to the signal, so that it is converted into a single-polarity signal, and impedance matching is performed through the impedance matching circuit.

[0022] Further, the step S2 comprises the following steps:

[0023] A stable clock signal is generated through an oscillator; and a modulated ultrasonic wave pulse signal is generated through the cooperation of the counters and comparators of each channel. The phase parameters, modulation parameters and other configuration information of each channel are stored in the memory. The multi-channel independent phase control technology is used to adjust the initial phase of each channel corresponding to each ultrasonic transducer unit through the phase-shifting module, so that the phase adjustment amount applied to each ultrasonic transducer unit is determined by the following formula:

[0024]

[0025] wherein, Δφ kl is the phase adjustment amount applied to the lth transducer unit on the kth ring; λ is the wavelength of the ultrasonic wave, which is determined by the carrier frequency f c and the sound speed c in the propagation medium; R k is the radius of the kth ring in the concentric circular array, wherein k is the ring serial number counted from inside to outside; α kl is the angular position of the transducer unit on the kth ring, which is the angle measured in the counterclockwise direction with respect to a preset reference axis in the array plane; θ is a desired target sound field elevation angle, which is defined as the included angle between the main lobe of the sound beam and the normal direction of the array; φ is a desired target sound field azimuth angle, which is defined as the included angle between the projection of the main lobe of the sound beam on the array plane and the preset reference axis; and the calculated phase adjustment amount Δφ klsuch that the ultrasound waves from all driven ultrasonic transducer units form constructive interference in a far field target direction determined by the target sound field elevation angle θ and the target sound field azimuth angle φ, thereby producing a pencil beam with a predetermined pointing.

[0026] Still further, the step S3 comprises the following steps:

[0027] The ultrasonic signal power amplifier array has a buffer, a boost voltage stabilizing power supply, a group of high-efficiency nonlinear amplifiers, and a group of gate drivers; the buffer is used to isolate the signal source from the amplifier array; the boost voltage stabilizing power supply provides a stable voltage for the power amplifier; each nonlinear amplifier adopts a half-bridge driving mode and realizes high-efficiency amplification through automatic dead zone control; and each gate driver ensures the safe operation of the corresponding power amplifier. The characteristic spacing of each ultrasonic transducer unit in the ultrasonic transducer array, which covers the radial size parameters defining the radii of concentric circles and the effective spacing between adjacent units on the same circular ring, is adapted to the center working wavelength (λ) of the ultrasonic modulation signal; and the adaptation between the characteristic spacing and the center working wavelength aims to optimize the directivity response diagram of the array.

[0028] Still further, the step S4 comprises the following steps:

[0029] The dynamic carrier control algorithm is a random sampling integral decision algorithm, which comprises the following core steps:

[0030] S401, signal sampling and energy evaluation: in a preset fixed time window T, the digital audio signal from the ADC is sampled N times at a determined sampling frequency, a group of sampling values {x k |k=1,…,n} is obtained, and the intensity state S of the audio signal is judged by calculating the average value of the sampling values; the N sampling points can be uniformly distributed in the time window T or selected according to a specific randomization strategy;

[0031] S402, threshold decision and carrier control: the calculated intensity state S is compared with a preset threshold value: when S is greater than a first preset threshold value (Threshold ON ), it is determined that there is an effective audio signal input, the control module enables the carrier output of the multi-channel ultrasonic modulator, and the system enters or remains in the working mode; when S is continuously lower than a second preset threshold value (Threshold OFF ) for a period of time, it is determined that there is no audio signal input, and the control module disables the carrier output of the multi-channel ultrasonic modulator, and the system enters or remains in the standby mode; Threshold OFF ≤Threshold ONTo achieve hysteresis comparison, prevent frequent switching at critical point) when, the determination is invalid or weak audio signal, the control module closes the carrier output of the modulator, the system enters energy saving standby mode.

[0032] Compared with the prior art, the beneficial effects of the present application are:

[0033] The present application proposes an energy-saving directional loudspeaker system which can control the angle range of sound field. The ultrasonic signal is amplified by high-efficiency nonlinear power amplifier, which improves the power conversion efficiency. Further, the present application combines specific pulse width modulation (PWM) technology with the inherent band-pass filtering characteristics of ultrasonic transducers, and through signal processing, it enables the recovery of audio signals from modulated ultrasonic waves at the receiving end, successfully converts PWM signals into equivalent amplitude modulation (AM) signals to realize the possibility of audio signal demodulation. By calculating and independently adjusting the initial phase of the signal driving each transducer unit, beamforming and three-dimensional spatial propagation direction control of the synthesized sound field beam are realized, so that the coverage angle and area of the sound field can be adjusted. Finally, the random sampling integral decision algorithm is used to monitor the intensity of the input audio signal in real time, and the ultrasonic carrier of the directional loudspeaker system is automatically controlled according to the monitoring results. This dynamic energy-saving management mechanism enables the system to quickly enter a low-power standby state when there is no audio signal or the signal is extremely weak, and quickly responds when there is audio input. The directional loudspeaker system proposed in the present application solves the key problems of the existing directional loudspeaker, such as insufficient flexibility in sound field angle range control, high overall energy consumption, and low running efficiency, and reduces the complexity and manufacturing cost of the system, achieving a balance of low power, high sound pressure level, low cost, and low weight. The half-bridge drive structure refers to a commonly used power electronic circuit topology for efficiently driving loads. It is usually composed of two switching devices and can provide bidirectional current or higher voltage. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0035] Figure 1 is a method flowchart of the present application;

[0036] Figure 2 is a hardware structure block diagram of the directional loudspeaker system in the present application;

[0037] Figure 3is the circuit structure schematic diagram of the audio signal preprocessing module in the application;

[0038] Figure 4 is the circuit structure schematic diagram of the ultrasonic wave modulator in the application;

[0039] Figure 5 is the circuit structure schematic diagram of the power amplifier array in the application;

[0040] Figure 6 is the layout schematic diagram of the concentric circle array of the ultrasonic wave transducer in the application;

[0041] Figure 7 is the detailed flow chart of the random sampling integral decision algorithm in the application;

[0042] Figure 8 is the detailed flow chart of the ultrasonic wave modulation and multi-channel independent phase control in the application;

[0043] Figure 9 is the principle schematic diagram of the multi-channel independent phase control technology realizing beam forming in the application;

[0044] Figure 10 is the waveform schematic diagram of the PWM modulated ultrasonic wave signal in the embodiment of the application;

[0045] Figure 11 is the polar coordinate distribution actual measurement diagram of the specific downward sound field angle and sound pressure level in the embodiment of the application;

[0046] Figure 12 is the contrast simulation diagram of the sound pressure spatial distribution of the ordinary loudspeaker and the directional loudspeaker system of the application under the same input;

[0047] Figure 13 is the power consumption comparison diagram of the system standby and working state in the embodiment of the application;

[0048] Figure 14 is the principle diagram of the equivalent AM envelope separated out after the PWM modulated signal is band pass filtered by the ultrasonic wave transducer;

[0049] Figure 15 is the overall PCB layout top layer diagram of the embodiment of the application;

[0050] Figure 16 is the overall PCB layout bottom layer diagram of the embodiment of the application;

[0051] Legend:

[0052] 10-audio signal preprocessing module

[0053] 11-audio input interface

[0054] 12 - 2-way hybrid coupler

[0055] 13 - Bias network

[0056] 14 - Impedance transformer

[0057] 15 - Analog to digital converter (ADC)

[0058] 20 - Multi-channel ultrasonic modulator

[0059] 21 - Ultra-high frequency oscillator

[0060] 22 - Phase shifting module (either integrated in the modulator or a separate module controlled by the controller)

[0061] 23 - Counter (core component of the modulator)

[0062] 24 - Comparator (core component of the modulator)

[0063] 25 - Memory (for storing parameters, accessible by the modulator or the controller)

[0064] 30 - Array of ultrasonic signal power amplifiers

[0065] 31 - Buffer

[0066] 32 - Step-up regulated power supply

[0067] 33 - Non-linear amplifier

[0068] 34 - Gate driver

[0069] 40 - Array of ultrasonic transducers

[0070] 41 - Ultrasonic transducer unit

[0071] 50 - Control module

[0072] 51 - Initialization unit

[0073] 52 - Logic processing unit

[0074] 53 - Core processor

[0075] 54 - DMA controller

[0076] 60 - Random sampling integration decision function unit / algorithm module (executed by the processor) DETAILED DESCRIPTION

[0077] The specific embodiments of the present application are described below to facilitate the understanding of the present application for those skilled in the art, but it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and determined by the appended claims, and all the inventions utilizing the concept of the present application are within the scope of protection.

[0078] Embodiments

[0079] The present application proposes an energy-saving directional loudspeaker system that can control the sound field angle range. The system uses an audio signal preprocessing module, a multi-channel ultrasonic modulator, a power amplifier array, a concentric circular distribution of ultrasonic transducer arrays, and a control module. Through multi-channel independent phase control technology and random sampling integral decision algorithm, the system realizes accurate regulation of sound spatial propagation direction (for example, the range of 0°-90° in pitch angle, combined with azimuth angle control), forms a pen-shaped sound beam, and dynamically starts and stops the carrier output according to the audio signal intensity, effectively reducing standby power consumption. The pen-shaped beam is a very narrow and highly directional sound beam, like a pencil.

[0080] S1, audio signal acquisition and preprocessing, the implementation method is as follows:

[0081] S101, in the actual application scene, the external audio signal is collected through the audio input interface (11), which can be a stereo signal;

[0082] S102, if the input is a stereo signal, use a two-way wave combining circuit (12) to combine left and right channel signals into a single channel signal. The single channel signal is then added with a preset DC component through a bias network (13) to convert it into a unipolar signal, and the signal pickup is optimized through an impedance transformer (14) to adapt to the input requirements of the subsequent analog-to-digital converter (ADC) (15), providing stable and compatible signal input for subsequent digital processing. The entire audio signal preprocessing process is completed by the audio signal preprocessing module (10).

[0083] S2, random sampling integral decision algorithm for audio signal detection, the implementation method is as follows:

[0084] S201, during system operation, the analog-to-digital converter (ADC) (15) in the control module (50) samples the unipolar audio signal from the audio signal preprocessing module (10) at a preset sampling frequency (for example, 40kHz or higher, depending on the ultrasonic carrier frequency and modulation bandwidth requirements) in a periodic or dynamically adjusted time window T (for example, T = 100 milliseconds) according to signal characteristics.

[0085] S202, from the sampling data of the time window, obtain N sampling points (for example, N=100). The N sampling points can be uniformly distributed or selected according to a specific randomization strategy aimed at improving the detection sensitivity of weak signals or specific signal patterns (for example, randomly selecting multiple sub-sections within the window and uniformly selecting points from each sub-section, or applying a small random jitter to the sampling time, etc.). The process is controlled by the core processor (53) in the control module (50) and implemented through the random sampling integration judgment function unit / algorithm module (60).

[0086] S203, the core processor (53) calculates the average absolute value of the N sampling points {x k |k=1,…,N} in the time window as an indicator S of the evaluation of the audio signal intensity state:

[0087]

[0088] S204, compare the calculated signal intensity indicator S with the preset opening threshold Threshold ON and the closing threshold Threshold OFF (usually Threshold OFF ≤ Threshold ON to introduce hysteresis characteristics to prevent frequent start-stop of the system due to small signal fluctuations near the critical point). Wherein, the hysteresis comparison refers to a control strategy in which the threshold for state switching depends on the current state. For example, the audio intensity threshold for switching from the working mode to the energy-saving mode can be lower than the threshold for switching from the energy-saving mode to the working mode. This comparison serves as the basis for determining whether the audio signal intensity meets the sound field output condition:

[0089] · When M>Threshold ON , it is determined that there is an effective audio signal input, and the control module (50) enables the carrier output of the multi-channel ultrasonic modulator (20), and the system enters or remains in the working mode;

[0090] · When S is continuously lower than Threshold OFF for a period of time (for example, for a total duration of T delay ), it is determined that there is no or extremely weak audio signal, and the control module (50) turns off the carrier output of the multi-channel ultrasonic modulator (20), and the system enters the energy-saving standby mode, thereby significantly reducing the system energy consumption.

[0091] S3, ultrasonic modulation and multi-channel independent phase control, the implementation method is as follows:

[0092] S301, a high-frequency oscillator (21) in the multi-channel ultrasonic modulator (20) generates a stable high-frequency carrier signal, as the basis for subsequent modulation and phase shifting, for example, a square wave or a sine wave with a frequency of 40 kHz or higher;

[0093] S302, in order to implement multi-channel independent phase control, first establish a coordinate system and define array and target beam pointing parameters: in order to accurately describe the positions of the transducer units and the pointing of the sound beam, a three-dimensional Cartesian coordinate system (X, Y, Z) is established, wherein the array plane of the ultrasonic transducer array (40) is arranged in the X-Y plane, and the geometric center of the array (i.e. the common center of all concentric circles) is located at the coordinate origin (0, 0, 0). The Z axis is perpendicular to the X-Y plane and points forward as the normal or axial direction of the array. The pointing of the target sound beam is defined by the elevation angle θ and the azimuth angle φ in the spherical coordinate system: the elevation angle θ is defined as the angle between the central axis of the main lobe of the target sound beam and the positive direction of the Z axis, and the value range is usually radians (corresponding to the front half of the radiation space). The azimuth angle φ is defined as the angle between the projection of the main lobe of the target sound beam on the X-Y plane and the positive direction of the X axis, and is usually positive in the counterclockwise direction, with a value range of 0 ≤ φ < 2π radians. The wavelength λ of the ultrasonic wave in the propagation medium (usually air) is determined by the carrier frequency f c and the sound speed c, that is

[0094] S303, define the geometric layout parameters of the concentric circular array (40): the ultrasonic transducer array (40) is composed of N rings concentric circular rings (for example, N rings may be 3 to 10 or more). The radius of the kth circular ring (l = 1, 2, …, N rings , numbered in order from inside to outside) is defined as R k . In an embodiment of the present application, the radii of the circular rings can be set according to the rule R k = n k · d rad , where d rad is a predetermined radial basic unit length (for example, it can be several millimeters to several centimeters according to the specific design), and n k is a dimensionless coefficient corresponding to the kth ring (for example, it can be an arithmetic sequence n k = k, or other sequences determined according to the optimization requirements of acoustic performance). On the kth circular ring, there are M k ultrasonic transducer units (41). The angular positions of these units on the circular ring (also relative to the positive direction of the X axis, measured counterclockwise) are denoted as α kl , where l = 0, 1, 2, …, M k-1). In a preferred embodiment, the transducer units on each ring are evenly distributed. Therefore, the Cartesian coordinate (x kl ,y kl ) can be expressed as:

[0095] x kl =R k cos(α kl )

[0096] y kl =R k sin(α kl )

[0097] S304, determining the phase adjustment amount of each transducer unit: in order to make the ultrasonic energy radiated by the array (40) form constructive interference at the target direction (θ, φ) in the far field, thereby generating a pencil-shaped acoustic beam with a predetermined direction, the core processor (53) in the control module (50) needs to calculate the initial phase adjustment amount Δφ required for the driving signal of each driven ultrasonic transducer unit (41) kl The phase adjustment amount Δφ kl This is to compensate for the acoustic path difference between the unit and the far-field equivalent wavefront in the target direction relative to the array center (or other selected reference point). kl ,y kl ) of the transducer unit, its effective path difference PD relative to the center of the array kl for:

[0098] PD kl =x kl sinθcosφ+y kl sinθsinφ=R k sinθcos(α kl -φ)

[0099] Phase adjustment Δφ applied to the lth transducer unit on the kth ring kl The calculation formula is as follows:

[0100]

[0101] The symbols in the formula are defined as above. The negative sign indicates a phase compensation convention to ensure in-phase superposition in the target direction.

[0102] S305, applying phase adjustment parameters and setting the beam control range: the core processor (53) calculates the phase adjustment parameters Δφ for all (or selected driven) transducer units in the array klThe phase parameters of each channel are stored in the memory (25). Each phase shift module (22) in the multi-channel ultrasonic modulator (20) performs accurate initial phase presetting or adjustment on the ultrasonic carrier signal of the corresponding channel according to the phase parameters of the channel read from the memory (25) or directly provided by the processor (53).

[0103] S306, the phase-adjusted channel high-frequency carrier signals are modulated with the audio signals from the audio signal preprocessing module (10) (after being digitized by the ADC (15)). The modulation can use high-resolution modulation techniques such as pulse width modulation (PWM), which is realized by the cooperation of the counter (23) and the comparator (24) in the modulator (20). The modulated high-resolution ultrasonic pulse signal contains audio information and preset phase information. Modulation parameters and configuration information (such as PWM duty cycle range, modulation depth, etc.) are also stored in the memory (25) and can be efficiently transmitted between the processor (53) and the modulator-related components through the direct memory access (DMA) controller (54) when needed.

[0104] S4, the power amplifier array and the ultrasonic transducer array are driven, and the implementation method is as follows:

[0105] S401, the modulated ultrasonic pulse signals output by the multi-channel ultrasonic modulator (20) are first passed through the buffer (31) for signal isolation and preliminary enhancement of driving capability to reduce the load impact on the modulator output and ensure stable signal transmission to the power amplifier array (30);

[0106] S402, the boost regulator power supply (32) provides stable and sufficient high voltage (for example, tens of volts to hundreds of volts, depending on the characteristics of the transducer and the required sound pressure level) for each nonlinear amplifier (33) in the power amplifier array (30);

[0107] S403, the signals of each channel are respectively amplified by the corresponding nonlinear amplifier (33). These nonlinear amplifiers preferably use an efficient class-D amplifier topology, for example, using a half-bridge driving method, and accurately control the switching of the power switch tube through the gate driver (34). Automatic dead zone control and other technologies are used to further improve the amplification efficiency and minimize signal distortion and power loss during switching;

[0108] S404, the power amplified channel modulation signals are transmitted to the corresponding ultrasonic transducer units (41) in the concentric circular ultrasonic transducer array (40) respectively. Each transducer unit (41) uses its piezoelectric effect to efficiently convert the input high-frequency modulation signal into ultrasonic vibration and radiate to space. Since each channel signal carries preset phase information, the coherent superposition of sound waves radiated by all units in the array eventually forms a modulated ultrasonic wave field carrying audio information with a specific direction and shape (pencil beam) in space, thereby realizing the accurate directional output of sound within a preset angle range.

[0109] S5, the overall system control and dynamic energy saving management is achieved by the following method:

[0110] S501, the control module (50) is the control core of the whole system, which can integrate an analog-to-digital converter (ADC) (15), a direct memory access (DMA) controller (54) and a core processor (53) (such as a microcontroller MCU or a digital signal processor DSP). This module realizes the whole process digital closed-loop management from digital acquisition of audio signals, signal processing, parameter configuration (ADC sampling rate, modulation parameters, phase values of each channel, etc.), to algorithm execution and peripheral control;

[0111] S502, the core processor (53) dynamically judges the intensity of the input audio signal in real time according to the result of the random sampling integral decision algorithm described in S2. Based on this judgment, the processor (53) controls the overall enablement or prohibition (start-stop control) of the ultrasonic carrier signal in the multi-channel ultrasonic modulator (20), ensuring that the system is in working mode (outputting directional sound beam) when there is valid audio input, and quickly switching to energy-saving standby mode (turning off the carrier, only maintaining the power consumption of the necessary monitoring circuit) when there is no valid audio input or the audio signal is extremely weak, thereby achieving significant energy saving effect and prolonging the service life of the system.

[0112] The present application realizes flexible and accurate control of the sound field direction (pitch angle and azimuth angle) and shape (pencil beam) by innovative multi-channel independent phase control technology combined with ultrasonic transducer arrays with specific geometric configurations (such as concentric circles), for example, the pitch angle can be adjusted within the range of 0°-90° (or wider, depending on the specific design). At the same time, the random sampling integral decision algorithm is used to replace the traditional full-time carrier output method, and the audio signal intensity is used as the basis for system control, realizing dynamic start-stop of ultrasonic output and significant optimization of energy consumption. Figures 1 to 6 The accompanying drawings (such as ) respectively show the method flowchart, overall hardware structure block diagram of the system, circuit structure schematic diagram of the audio signal preprocessing module, circuit structure schematic diagram of the ultrasonic modulator, circuit structure schematic diagram of the power amplifier array and layout schematic diagram of the ultrasonic transducer array.Figure 7 The flow of the random sampling integral decision algorithm is illustrated in detail. Figure 8 The flow of ultrasonic wave modulation and multi-channel independent phase control is illustrated in detail. Figure 9 The principle of multi-channel independent phase control technology realizing beamforming by adjusting the phase of each unit is illustrated. Figure 10 A waveform example of a modulated ultrasonic wave signal is given.

[0113] In order to verify the sound field directivity and energy efficiency of the energy-saving directional loudspeaker system with controllable sound field angle range, an experimental system was built and tested in an approximate free field environment. The experimental results show that when the target sound beam is directed in a specific direction (for example, the pitch angle is 0° and the azimuth angle is 0°), the sound pressure level measured by the 440Hz audio signal demodulation at the main receiving point (target direction) is 87dB at a distance of 2 meters from the array center. At the same time, the spatial distribution of the sound field is scanned and measured (such as the sound pressure level polar distribution diagram shown in Figure 11 The results show that the sound pressure level in the main lobe direction (a small solid angle near the target direction) is significantly higher than in all other directions, while the side lobe (or side lobe) and backward radiation sound pressure levels are significantly suppressed, usually more than 20dB lower than the main lobe. This clearly shows that the system can realize high focusing of sound energy in the target direction, forming a pencil-shaped sound beam with good directivity, greatly improving the directivity and energy utilization efficiency of sound propagation. Figure 12 Details for comparison with ordinary loudspeakers are shown.

[0114] In terms of energy consumption, the experimental results show that when there is no audio signal input or the audio signal strength is much lower than the Threshold OFF , the system can quickly enter the energy-saving standby mode (for example, within hundreds of milliseconds to several seconds) according to the random sampling integral decision algorithm, effectively reducing unnecessary energy consumption. In this standby state, the total power consumption of the system is only 1.75W. In the working state, when the sound pressure level of 87dB (440Hz audio after demodulation) is output in the target direction at a distance of 2 meters, the total working power of the system is measured to be 17.345W. Compared with the directional loudspeaker solutions reported in the literature or on the market that use traditional control strategies, the standby power consumption is generally greater than 2W or even up to 5W, and the working power consumption is higher. The standby power consumption of the present invention is reduced by about 30% or more, and the working energy efficiency when reaching similar sound pressure level output is also significantly improved (for example, the working power may be only 30%-50% of the traditional full-time carrier scheme at the same acoustic output, depending on the comparison object). For example, Figure 13The power consumption of the system in standby and working states is clearly shown, which demonstrates the energy-saving effect. This improvement not only reduces the operation cost, but also significantly reduces the overall heat of the system, which is beneficial to improve the reliability of electronic components and prolong the overall service life of the equipment, and has significant economic benefits and environmental advantages. In addition, regarding the modulation mode, as shown in Figure 14 The present application can adopt digital modulation technology such as PWM, combined with the band-pass filtering characteristics of the ultrasonic transducer itself, to realize self-demodulation of the audio signal in the air, or demodulation through a specific receiving technology. Figure 15 、 Figure 16 The overall PCB layout top view and bottom view of the embodiment of the present application are respectively shown.

Claims

1. An energy-saving directional speaker system capable of controlling the angle range of the sound field, characterized in that: include: S1. The audio signal preprocessing module combines, biases, and performs impedance matching on the input audio signal to provide a unipolar audio signal with a preset DC bias for subsequent modules. S2. Processing the signal from the audio signal preprocessing module through a multi-channel ultrasonic modulator, generating an independent ultrasonic pulse signal with predetermined modulation parameters for each channel through a counter and a comparator, and performing independent phase adjustment on each channel signal according to the instruction; S3, amplifying the power of the independent modulated signals of each channel through an ultrasonic signal power amplifier array to provide sufficient driving power for corresponding units of the ultrasonic transducer array; S4. Converting the corresponding electrical signals from the power amplifier array into ultrasonic signals through an ultrasonic transducer array. The ultrasonic signals generated by the transducer units are spatially interfered and superimposed based on independent phase adjustment of each channel to form a directionally propagating sound field, thereby achieving spatial distribution control of the sound. S5. The unipolar audio signal from the audio signal preprocessing module is collected at a preset frequency through the analog-to-digital converter (ADC) in the control module; the ADC sampling data is transferred to the storage area through the direct memory access (DMA) controller; the core processor initializes and configures the system hardware resources, sets the ADC sampling parameters, the ultrasonic modulation parameters of each channel, and the phase parameters required by the phase shift module, and executes the dynamic carrier control algorithm to dynamically control the start and stop of the ultrasonic carrier signal in the multi-channel ultrasonic modulator according to the audio signal strength, thereby turning off the carrier when there is no valid audio output or the audio output is extremely weak, thereby realizing the switching between the working mode and the energy-saving standby mode.

2. The energy-saving directional speaker system capable of controlling the sound field angle range according to claim 1, characterized in that: The steps of step S1 are as follows: The audio input interface receives an external audio signal and synthesizes the stereo signal into a mono signal through the left and right channel combiner circuit. The synthesized signal passes through the bias network, which adds a DC component to the signal, converting it into a unipolar signal. The impedance matching circuit is used for impedance matching.

3. The energy-saving directional speaker system capable of controlling the sound field angle range according to claim 1, characterized in that: The steps of step S2 are as follows: An oscillator generates a stable clock signal; a counter and comparator pair in each channel work together to generate a modulated ultrasonic pulse signal. A memory stores configuration information such as the phase parameters and modulation parameters of each channel. The multi-channel independent phase control technology is used to adjust the initial phase of each channel corresponding to each ultrasonic transducer unit through the phase shift module, so that the phase adjustment amount applied to each ultrasonic transducer unit is determined by the following formula: Among them, Δφ kl is the phase adjustment applied to the lth transducer unit on the kth ring; λ is the wavelength of the ultrasonic wave, which is determined by the carrier frequency f c and the speed of sound c in the propagation medium; R k is the radius of the kth ring in the concentric circle array, where k is the ring number counted from the inside out; α kl is the angular position of the transducer unit on the kth ring, which is an angle measured counterclockwise relative to a preset reference axis in the array plane; θ is an expected target sound field pitch angle, which is defined as the angle between the main lobe of the sound beam and the normal direction of the array; φ is an expected target sound field azimuth angle, which is defined as the angle between the projection of the main lobe of the sound beam on the array plane and the preset reference axis; and by applying the calculated phase adjustment amount Δφ to each unit kl , so that the ultrasonic waves from all driven ultrasonic transducer units form constructive interference in the far-field target direction determined by the target sound field pitch angle θ and the target sound field azimuth angle φ, thereby generating a pencil-shaped acoustic beam with a predetermined direction.

4. The energy-saving directional speaker system capable of controlling the sound field angle range according to claim 1, characterized in that: The steps of step S3 are as follows: The ultrasonic signal power amplifier array comprises a buffer, a boost-regulated power supply, a high-efficiency nonlinear amplifier group, and a gate driver group. The buffer is used to isolate the signal source from the amplifier array. The boost-regulated power supply provides a stable voltage for the power amplifier. Each nonlinear amplifier uses a half-bridge drive scheme, achieving efficient amplification through automatic dead-zone control. Each gate driver ensures the safe operation of the corresponding power amplifier. The characteristic spacing of each ultrasonic transducer unit in the ultrasonic transducer array, which includes the radial dimension parameters that define the radius of each concentric circle and the effective spacing between adjacent units on the same circle, is adapted to the central operating wavelength (λ) of the ultrasonic modulated signal. Furthermore, this adaptive relationship between the characteristic spacing and the central operating wavelength is intended to optimize the array's directivity response pattern.

5. The energy-saving directional speaker system capable of controlling the sound field angle range according to claim 1, characterized in that: The steps of step S4 are as follows: The dynamic carrier control algorithm is a random sampling integral decision algorithm that includes the following core steps: S401, signal sampling and energy evaluation: within a preset fixed time window T, the digital audio signal from the ADC is sampled N times at a determined sampling frequency to obtain a set of sampling values ​​{x k |k=1,…,N}, and calculate the average value of these sample values To determine the strength state S of the audio signal; the N sampling points may be uniformly distributed within the time window T, or selected according to a specific randomization strategy; S402, threshold judgment and carrier control: Compare the calculated strength state S with the preset threshold: When S is greater than the first preset threshold (Threshold ON ), it is determined that it is a valid audio signal input, the control module enables the carrier output of the multi-channel ultrasonic modulator, and the system enters or maintains the working mode; when S is lower than the second preset threshold (Threshold OFF , where Threshold OFF ≤Threshold ON To achieve hysteresis comparison and prevent frequent switching at critical points), when it is determined to be an invalid or extremely weak audio signal, the control module turns off the carrier output of the modulator, causing the system to enter energy-saving standby mode.

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