CN221381171U

CN221381171U - Playing device

Info

Publication number: CN221381171U
Application number: CN202323323804.9U
Authority: CN
Inventors: 潘军
Original assignee: Beijing Zhongjia Space Display Design Co ltd
Current assignee: Beijing Zhongjia Space Display Design Co ltd
Priority date: 2023-12-06
Filing date: 2023-12-06
Publication date: 2024-07-19
Anticipated expiration: 2033-12-06

Abstract

The utility model relates to the technical field of audio, in particular to a playing device, which comprises: the pre-amplifying module is used for receiving the sound signal and amplifying the sound signal; the analog-to-digital conversion module is used for converting the amplified sound signals into digital sound signals; the pulse wave conversion module is used for converting the digital sound signal into a pulse wave signal; the power amplification module comprises a class-D audio power amplifier and is used for amplifying the power of the pulse wave signal; and the ultrasonic module is connected with the power amplification module and is used for outputting ultrasonic waves to a target area according to the pulse wave signals after power amplification so as to play the sound signals in the target area. The embodiment of the utility model can enable the playing device to efficiently and accurately focus the sound on the specific target area, thereby creating clear sound effect in the area and improving the application flexibility of the playing device.

Description

Playing device

Technical Field

The utility model relates to the technical field of audio, in particular to a playing device.

Background

In the field of acoustic technology, sound is accurately focused on a specific target area, so that a clear sound effect is created in the area, but sound is hardly heard in other areas, and the method has wide application requirements in the fields of business, entertainment, communication, military and the like. Currently, the related art cannot efficiently and accurately achieve accurate focusing of sound at a specific target area, thereby creating a clear sound effect in the area.

Disclosure of utility model

According to an aspect of the present utility model, there is provided a playback apparatus including:

The pre-amplifying module is used for receiving the sound signal and amplifying the sound signal;

the analog-to-digital conversion module is connected with the pre-amplification module and is used for converting the amplified sound signal into a digital sound signal;

the pulse wave conversion module is connected with the analog-to-digital conversion module and used for converting the digital sound signal into a pulse wave signal;

the power amplification module comprises a class-D audio power amplifier, and is connected with the pulse wave conversion module and used for amplifying the power of the pulse wave signal;

and the ultrasonic module is connected with the power amplification module and is used for outputting ultrasonic waves to a target area according to the pulse wave signals after power amplification so as to play the sound signals in the target area.

In one possible implementation manner, the sound signals include a left channel sound signal and a right channel sound signal, the pre-amplifying module includes a first pre-amplifying unit and a second pre-amplifying unit, the first pre-amplifying unit and the second pre-amplifying unit each include a first operational amplifier and a second operational amplifier which are cascaded, the first operational amplifier is used for voltage biasing and amplifying the sound signals, and the second operational amplifier is set in a voltage following mode to isolate and output the amplified sound signals.

In one possible implementation, the analog-to-digital conversion module includes:

The analog-to-digital converter is used for respectively carrying out analog-to-digital conversion on the amplified left channel sound signal and the amplified right channel sound signal to obtain a left channel digital sound signal and a right channel digital sound signal;

And the operation unit is connected with the analog-digital converter and is used for obtaining the digital sound signals by utilizing the left channel digital sound signals and the right channel digital sound signals.

In one possible embodiment, the pulse wave conversion module includes:

The PWM signal generator is used for generating a first PWM carrier signal and a second PWM carrier signal which both have target frequencies, and the first PWM carrier signal and the second PWM carrier signal have different duty ratios;

The mixer is connected with the PWM signal generator, modulates the digital sound signals to the first PWM carrier signal and the second PWM carrier signal respectively to obtain two paths of pulse wave signals with different duty ratios, and inputs the two paths of pulse wave signals with different duty ratios to two input ends of the power amplification module respectively.

In one possible implementation, the target frequency is 40KHz.

In one possible embodiment, the apparatus further comprises:

and the position detection module is used for determining the distance and the direction of the target object relative to the ultrasonic module so as to determine the target area.

In one possible embodiment, the amplification parameter of the power amplification module is proportional to the distance of the target object relative to the ultrasound module.

In one possible implementation, the power amplification module comprises a plurality of power amplification units, the ultrasonic module comprises a plurality of ultrasonic emission units,

When the amplification parameter is lower than a preset value, the number of the power amplification units in the power amplification module and the number of the ultrasonic wave transmitting units in the ultrasonic wave module in the working state are reduced to the preset number.

In one possible embodiment, the position detection module includes a ToF sensor for determining a distance of the target object relative to the ultrasound module, and a direction sensor for determining a direction of the target object relative to the ultrasound module.

In one possible implementation, the device further comprises at least one of a bluetooth module and a WiFi module, and a power supply module for supplying power to each component of the device.

The embodiment of the utility model comprises the following steps of: the pre-amplifying module is used for receiving the sound signal and amplifying the sound signal; the analog-to-digital conversion module is used for converting the amplified sound signals into digital sound signals; the pulse wave conversion module is used for converting the digital sound signal into a pulse wave signal; the power amplification module comprises a class-D audio power amplifier and is used for amplifying the power of the pulse wave signal; the ultrasonic module is used for outputting ultrasonic waves to a target area according to the pulse wave signals after power amplification so as to play the sound signals in the target area, so that the playing device can efficiently and accurately focus the sound on a specific target area, a clear sound effect is created in the area, and the application flexibility of the playing device can be improved.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the utility model as claimed. Other features and aspects of the present utility model will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the utility model and together with the description, serve to explain the principles of the utility model.

Fig. 1 shows a schematic diagram of a playback apparatus according to an embodiment of the present utility model.

Fig. 2 shows a schematic diagram of a playback apparatus according to an embodiment of the present utility model.

Fig. 3 shows a schematic diagram of a pre-amplification module according to an embodiment of the utility model.

Fig. 4 shows a schematic diagram of a power amplifier module according to an embodiment of the utility model.

Fig. 5 shows a schematic diagram of a power supply module according to an embodiment of the utility model.

Fig. 6 shows a schematic diagram of a function switching module according to an embodiment of the utility model.

Fig. 7 shows a schematic diagram of a ToF sensor circuit in a position detection module according to an embodiment of the utility model.

Fig. 8 shows a schematic layout of an ultrasound module according to an embodiment of the utility model.

Fig. 9 shows a schematic size diagram of an ultrasonic array in a playing device according to an embodiment of the utility model.

Detailed Description

Various exemplary embodiments, features and aspects of the utility model will be described in detail below with reference to the drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Although various aspects of the embodiments are illustrated in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

In the description of the present utility model, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the present utility model and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present utility model.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present utility model, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

The term "and/or" is herein merely an association relationship describing an associated object, meaning that there may be three relationships, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In addition, the term "at least one" herein means any one of a plurality or any combination of at least two of a plurality, for example, including at least one of A, B, C, may mean including any one or more elements selected from the group consisting of A, B and C.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better illustration of the utility model. It will be understood by those skilled in the art that the present utility model may be practiced without some of these specific details. In some instances, well known methods, procedures, components, and circuits have not been described in detail so as not to obscure the present utility model.

Referring to fig. 1, fig. 1 is a schematic diagram of a playing device according to an embodiment of the utility model.

As shown in fig. 1, the apparatus includes:

A pre-amplifying module 10 for receiving a sound signal and amplifying the sound signal;

the analog-to-digital conversion module 20 is connected to the pre-amplification module 10 and is used for converting the amplified sound signal into a digital sound signal;

A pulse wave conversion module 30, connected to the analog-to-digital conversion module 20, for converting the digital sound signal into a pulse wave signal;

The power amplification module 40 comprises a class D audio power amplifier, and the power amplification module 40 is connected to the pulse wave conversion module 30 and is used for amplifying the power of the pulse wave signal;

and an ultrasonic module 50, connected to the power amplification module 40, for outputting ultrasonic waves to a target area according to the pulse wave signal after power amplification, so as to play the sound signal in the target area.

The embodiment of the utility model comprises the following steps of: a pre-amplifying module 10 for receiving a sound signal and amplifying the sound signal; an analog-to-digital conversion module 20 for converting the amplified sound signal into a digital sound signal; a pulse wave conversion module 30 for converting the digital sound signal into a pulse wave signal; the power amplification module 40 comprises a class-D audio power amplifier, and is used for amplifying the power of the pulse wave signal; the ultrasonic module 50 is configured to output ultrasonic waves to a target area according to the pulse wave signal after power amplification, so as to play the sound signal in the target area, so that the playing device can efficiently and accurately focus the sound on a specific target area, thereby creating a clear sound effect in the area, and improving the flexibility of the application of the playing device.

The specific implementation manners of the pre-amplifying module 10, the analog-digital conversion module 20, the pulse wave conversion module 30, the power amplification module 40 and the ultrasonic module 50 are not limited, and can be set by a person skilled in the art according to actual situations and needs, and the pre-amplifying module 10, the analog-digital conversion module 20, the pulse wave conversion module 30, the power amplification module 40 and the ultrasonic module 50 in the embodiment of the utility model can be realized by hardware circuits.

Referring to fig. 2, fig. 2 is a schematic diagram of a playing device according to an embodiment of the utility model.

In an example, as shown in fig. 2, in a possible implementation manner, the apparatus may further include a communication module 60, where the communication module 60 may include at least one of a bluetooth module, a WiFi module, and the like, and in an embodiment of the present utility model, by setting a wireless communication module such as a bluetooth module, a WiFi module, and the like, flexibility of an application of the playing apparatus may be improved, and diversity of application scenarios may be expanded. Of course, the communication module 60 of the present embodiment also includes a wired communication mode, such as receiving audio signals through a 3.5mm audio interface connection to a wired headset.

In one possible implementation, as shown in fig. 2, the apparatus may further include an input-output (I/O) module 70, where the I/O module 70 includes a plurality of input-output interfaces for connecting with other modules to transmit data and signals.

In one example, as shown in fig. 2, the communication module 60, the analog-to-digital conversion module 20, the pulse wave conversion module 30, and the input-output module 70 may all be disposed in the same component, which may be, for example, a processing component, which may include, but is not limited to, a separate processor, or a combination of separate components, in one example. The processor may include a controller in an electronic device having the functionality to execute instructions, and may be implemented in any suitable manner, for example, by one or more Application Specific Integrated Circuits (ASICs), digital Signal Processors (DSPs), digital Signal Processing Devices (DSPDs), programmable Logic Devices (PLDs), field Programmable Gate Arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic elements. Within the processor, the executable instructions may be executed by hardware circuits such as logic gates, switches, application SPECIFIC INTEGRATED Circuits (ASIC), programmable logic controllers, and embedded microcontrollers. Preferably, the processing component may be a microprocessor, for example.

In one possible implementation, the analog-to-digital conversion module 20 may include:

The processing unit may be the processing unit, and the embodiment of the present utility model does not limit a specific implementation manner of obtaining the digital sound signal by using the left channel digital sound signal and the right channel digital sound signal, and a person skilled in the art may use related technologies according to actual situations and needs.

In one possible implementation, the pulse wave conversion module 30 may include:

The mixer is connected to the PWM signal generator, and modulates the digital sound signal to the first PWM carrier signal and the second PWM carrier signal, so as to obtain two paths of pulse wave signals with different duty ratios, and inputs the two paths of pulse wave signals with different duty ratios to two input ends of the power amplifier module 40.

The embodiment of the utility model does not limit the specific implementation modes of the PWM signal generator and the mixer, and the implementation modes can be set by a person skilled in the art according to actual situations and needs.

In one possible implementation, the target frequency may be 40KHz, although other frequencies are possible.

The pre-amplified left and right channel signals reach the ADC module of the microprocessor, the ADC module converts the signals into digital quantity specific values, and the microprocessor adds and averages the obtained values to obtain the converted stereo digital quantity signals. The pulse wave conversion module 30 (such as a PWM carrier generator) generates a 40khz PWM wave, and the microprocessor converts the processed stereo digital quantity signal into a form of PWM waves with different duty ratios; the final signal to be input to the post-stage power amplifier is obtained, and because the required post-stage power amplifier chip supports the input of two paths of signals, the microprocessor can output two paths of PWM waves with the same different duty ratios as the signal input of the post-stage power amplifier chip. The two paths of signals are used for achieving the purposes of reducing power consumption and noise by stopping one path of signal input when the volume is adjusted.

In one possible embodiment, as shown in fig. 2, the apparatus may further include a position detection module 90 for determining a distance and a direction of a target object with respect to the ultrasonic module 50 to determine the target area.

The specific implementation manner of the position detection module 90 in the embodiment of the present utility model is not limited, and a person skilled in the art may adopt a suitable technical scheme according to actual situations and needs. For example, in one possible implementation, the position detection module 90 may include a ToF sensor for determining a distance of the target object relative to the ultrasound module 50, and a direction sensor for determining a direction of the target object relative to the ultrasound module 50. The number and specific setting positions of the ToF sensors and the direction sensors are not limited, and can be set by a person skilled in the art according to actual situations and needs.

In one possible embodiment, the amplification parameters of the power amplification module 40 are proportional to the distance of the target object relative to the ultrasound module 50.

In one possible implementation, the power amplifier module 40 may include at least one path, such as 2 paths, and multiple paths of power amplifier units, and the ultrasonic module 50 includes at least one path, such as 2 paths, and multiple paths of ultrasonic wave transmitting units,

When the amplification parameter is lower than a preset value (for example, 50% of the amplification parameter corresponding to the full volume), the number of power amplifying units in the power amplifying module 40 and the number of ultrasonic transmitting units in the ultrasonic module 50 in the working state are reduced to a preset number, for example, 1.

In one possible embodiment, the sound signals include a left channel sound signal and a right channel sound signal, and the volume adjustment can be performed through two separate knobs.

Referring to fig. 3, fig. 3 shows a schematic diagram of a pre-amplifier module 10 according to an embodiment of the utility model.

Illustratively, the pre-amplifying module 10 includes a first pre-amplifying unit and a second pre-amplifying unit, where the first pre-amplifying unit and the second pre-amplifying unit each include a first operational amplifier and a second operational amplifier that are cascaded, the first operational amplifier is used for voltage biasing and amplifying the sound signal, and the second operational amplifier is set in a voltage following mode to isolate and output the amplified sound signal.

Taking a wired mode as an example, a 3.5mm audio interface is adopted in the wired mode connection, a left channel sound signal and a right channel sound signal pass through respective pre-amplifying units, namely a first operational amplifier and a second operational amplifier, the first operational amplifier is biased and amplified by voltage, the second operational amplifier is subjected to voltage following, and the front stage and the rear stage are isolated due to the input high impedance characteristic of the operational amplifier, so that the safety of an audio output end is improved.

For example, as shown in fig. 3, the adjusting knobs of the left channel sound signal and the right channel sound signal may be respectively implemented by the sliding varistors R24 and R29, and the adjusting of the sound magnitudes and the equalization of the left channel sound signal and the right channel sound signal may be implemented by changing the resistance values of the sliding varistors R24 and R29.

As shown IN fig. 3, the left-channel sound signal passes through the slide rheostat R24 and then reaches the first pre-amplifying unit through the capacitor C41 and the resistor U55, the first operational amplifier of the first pre-amplifying unit is used for biasing and amplifying, the positive input terminal (+ina) of the first operational amplifier receives the power supply voltage (3V 3) through the resistor U56, the negative input terminal (-INA) is connected to the resistor U55 and the resistor R20, the other end of the resistor R20 is connected to the output terminal OUTA and the positive input terminal (+inb) of the second operational amplifier, the second operational amplifier performs voltage following, the output terminal OUTB of the second operational amplifier is connected to the negative input terminal (-INB) and outputs the amplified left-channel signal (l_in) through the capacitor C42.

As shown IN fig. 3, the right-channel sound signal passes through the slide rheostat R29, then passes through the capacitor C46, (l_in) resistor U57, and reaches the second pre-amplifying unit, where the first operational amplifier is used for biasing and amplifying, the positive input terminal of the first operational amplifier receives the power supply voltage (3V 3) through the resistor U59, the output terminal OUTA is connected to the resistor U57 and the resistor R28, the other terminal of the resistor R28 is connected to the output terminal OUTA and the positive input terminal of the second operational amplifier, the second operational amplifier performs voltage following, and the output terminal OUTB thereof is connected to the negative input terminal (-INB) and outputs the amplified right-channel signal (r_in) through the capacitor C47.

Illustratively, as shown in fig. 3, the input high-impedance characteristic of the operational amplifier enables the front stage and the rear stage to be isolated, so that the safety of the audio output end is improved. The left and right sound channel signals processed by the double operational amplifiers are transmitted to the microprocessor; if WiFi or Bluetooth wireless connection is used, the left and right channel signals skip pre-amplification and directly enter the microprocessor.

In one possible embodiment, the apparatus may further comprise a power supply module to power the various components of the apparatus.

Referring to fig. 4 and 5, fig. 4 shows a schematic diagram of a power amplifier module 40 according to an embodiment of the utility model, and fig. 5 shows a schematic diagram of a power supply module according to an embodiment of the utility model.

For example, the power amplifier module 40 may include a class D audio power amplifier, as shown in fig. 4, where the class D audio power amplifier includes a class D power amplifier chip U53, and supports two signal inputs and can control two outputs respectively.

As shown in fig. 5, the power supply module in the embodiment of the utility model uses a 12V interface to supply power, and a power supply conversion circuit is built in the power supply module to respectively convert 12V into 5V and convert 5V into 3.3V for internal use of the system, and the 12V is used by a later stage power amplifier to drive the ultrasonic probe to work. The power supply module further comprises a power indicator lamp for displaying the working state of the power supply module.

For example, as shown in fig. 4, the 4/10 pins of the class D power amplifier chip U53 are two signal input pins, and are connected to two output terminals (two output terminals of the pulse wave conversion module 30) of the microprocessor, and receive two PWM waves with different duty ratios. The resistor R17 and the resistor R18 of the class D power amplifier chip U53 are configuration resistors for configuring the output gain. And the 12 pins of the D-type power amplifier chip U53 are MUTE MUTE pins, and enter a MUTE mode when the MUTE MUTE pins are set to be high level. While the MUTE pin is connected to the normally open pin of the power switch SW1 in the power module.

For example, when the power switch SW1 is normally closed and turned on during power-up, as shown in fig. 4, the capacitor C38 in the class D power amplifier chip U53 of the power amplifier module 40 is being charged, the 12-pin MUTE pin is at a high level, and after the capacitor C38 is charged, the 12-pin MUTE pin is at a low level. Pop sound (pop sound) occurring at the time of power-up can be avoided. When the power supply is turned off, the power switch SW1 is normally turned on, and the MUTE pin is turned on, at the moment, the capacitor in the power supply module is still electrified, and the MUTE pin is in a high-level MUTE mode, so that pop sound during shutdown is avoided.

As shown in fig. 4, the 27 pins and 29 pins, the 21 pins and 23 pins in the class D power amplifier chip U53 are two sets of differential outputs, namely two paths CH1 and CH 2; the capacitance values of the capacitor C3, the capacitor C4 and the capacitor C24, the capacitor C45 and the 4 capacitors in the class-D power amplifier chip U53 in the power supply module are 1000uf capacitors, and the power amplifier chip has a certain inhibition effect on the switching noise of the chip. The 4 inductors of the inductor L1, the inductor L2, the inductor L3 and the inductor L4 in the class D power amplifier chip U53 are used for improving stability and efficiency of the power amplifier circuit, and providing signal filtering and suppressing interference signals.

Referring to fig. 6, fig. 6 shows a schematic diagram of a function switching module 80 according to an embodiment of the utility model.

As shown in fig. 6, the function switching module 80 is connected to the input/output module 70 of the microprocessor, and the function switching module 80 is, for example, a function switching switch SW2, so that a user can select the function switching switch SW2 and configure to select whether to turn on the function of automatically changing the volume according to the distance between the human bodies after the connection using wifi/bluetooth. By way of example, the volume level may be reduced stepwise, e.g. up to 1 meter, when a person approaches within 4 meters, e.g. by default of 100% volume, calculated as the distance of the most 4 meters, the volume being adjusted to 40%. When the volume is less than 50% (preset value), the PWM signal after the second path conversion output by the microprocessor is empty, the second path output of the later-stage power amplifier is also closed, and the second path ultrasonic probe stops working, so that the purposes of saving power consumption and reducing noise are achieved.

Referring to fig. 7, fig. 7 is a schematic diagram of a ToF sensor circuit in the position detection module 90 according to an embodiment of the utility model.

By way of example, embodiments of the present utility model may enable location distance detection of a multi-zone target object by placing a ToF sensor circuit as shown in fig. 7 in each zone. Of course, the ToF sensor circuit shown in fig. 7 is exemplary and should not be construed as limiting embodiments of the utility model.

Referring to fig. 8, fig. 8 shows a schematic layout of an ultrasonic module 50 according to an embodiment of the present utility model.

For example, as shown in fig. 8, two ultrasonic probes, i.e., a first output and a second output, may be arranged, and a ranging sensor, such as a ToF sensor, may be arranged at a central position to achieve efficient and accurate detection of the distance of the ultrasonic module 50 from the target object. Preferably, the two signals are cross-connected in the sensor probe array, and the multi-zone tof sensor is arranged at the right middle position of the front surface of the sound box. Illustratively, two output channels (CH 1/CH 2) of the class D power amplifier chip U53 are connected to two ultrasonic probes of the ultrasonic module 50, and PWM signals with different duty ratios drive the ultrasonic probes to vibrate after passing through a later stage power amplifier, so that generated ultrasonic waves reach a target area, and the ultrasonic waves have a self-demodulation effect in air to obtain audible sound waves. For example, the single-path load of the rear-stage power amplifier is 50w of power, the number of the single-path ultrasonic probes is 180 at most, the number of the ultrasonic probes is 360, and different numbers can be selected according to requirements.

Referring to fig. 9, fig. 9 is a schematic diagram illustrating the dimensions of an ultrasonic array in a playing device according to an embodiment of the utility model.

It should be understood that the size of the ultrasonic horn shown in fig. 9 is exemplary and should not be construed as limiting the embodiments of the present utility model.

The playing device of the embodiment of the utility model can be an ultrasonic directional wireless sound box, can identify the position of a target object (such as a human body), adjusts the volume according to the distance and the azimuth of the target object, and realizes accurate and efficient playing of the audio in a target area based on the characteristics of high directivity and self-demodulation of ultrasonic wave in air propagation.

According to the foregoing description, the sound signal converts the left and right channel signals of the audio input into specific values of visual digital quantity through a digital-to-analog converter (ADC) of the microprocessor in a wired transmission process, and the microprocessor adds the obtained values and averages the obtained values to obtain the converted stereo digital quantity signal. The microprocessor generates a 40khz PWM carrier wave, converts the processed stereo digital quantity signal into a PWM wave form, namely PWM waves with different duty ratios obtained by referring to the input audio signal, drives the ultrasonic probe to vibrate through a d-type power amplifier to emit ultrasonic waves, and has a self-demodulation effect in air. The ultrasonic wave has high directivity, the sound wave in the sound producing area is strong, and the sound wave is weak or even absent in the sound producing area.

The embodiment of the utility model adopts the class D audio power amplifier, can realize single-channel 50w load, and has the characteristics of high effective rate, small volume and the like compared with the common linear class AB power amplifier circuit, and under ideal conditions, the class D power amplifier has the efficiency of 100 percent, the class B power amplifier has the efficiency of 78.5 percent and the class A power amplifier has the efficiency of 50 percent or 25 percent. The back-stage power amplifier uses 4 1000uf capacitors to inhibit the switching noise of the chip to a certain extent.

Compared with the traditional ultrasonic sound box, the embodiment of the utility model uses the multi-region tof sensor, 8x8 or 4x4 pixels can be selected, and the distance of each region measurement target can reach 4 meters at most. Whether the target moves or not can be detected, and whether the function of automatically changing the volume according to the distance between the human bodies is started or not can be selected through a function change switch on the body and configuration selection after wifi/Bluetooth connection is used. The sound box is calculated according to the distance of the most 4 meters, such as a default 100 percent sound box, when people approach in the range of 4 meters, the sound volume level is gradually reduced, such as reaching the position of 1 meter, and the sound volume is adjusted to be 40 percent. When the sound volume is lower than 50%, the pwm signal after the second conversion output by the microprocessor is empty, the second output of the rear-stage power amplifier is closed, and the second ultrasonic probe stops working, so that the purposes of saving power consumption and reducing noise are achieved.

The foregoing description of embodiments of the utility model has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described. The terminology used herein was chosen in order to best explain the principles of the embodiments, the practical application, or the improvement of technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A playback device, the device comprising:

2. The apparatus of claim 1, wherein the sound signals comprise a left channel sound signal and a right channel sound signal, the pre-amplification module comprises a first pre-amplification unit and a second pre-amplification unit, the first pre-amplification unit and the second pre-amplification unit each comprise a first operational amplifier and a second operational amplifier in cascade connection, the first operational amplifier is used for voltage biasing and amplifying the sound signals, and the second operational amplifier is set in a voltage following mode to isolate the amplified sound signals.

3. The apparatus of claim 2, wherein the analog-to-digital conversion module comprises:

4. The apparatus of claim 3, wherein the pulse wave conversion module comprises:

5. The apparatus of claim 4, wherein the target frequency is 40KHz.

6. The apparatus of claim 1, wherein the apparatus further comprises:

7. The apparatus of claim 6, wherein the amplification parameter of the power amplification module is proportional to the distance of the target object relative to the ultrasound module.

8. The apparatus of claim 7, wherein the power amplifier module comprises a plurality of power amplifier units, the ultrasonic module comprises a plurality of ultrasonic transmitter units,

9. The apparatus of claim 6, wherein the position detection module comprises a ToF sensor for determining a distance of the target object relative to the ultrasound module, and a direction sensor for determining a direction of the target object relative to the ultrasound module.

10. The device of claim 1, further comprising at least one of a bluetooth module, a WiFi module, and a power module to power the various components of the device.