Impedance adaptive circuit, wireless audio transmission device and audio system

Abstract

The application discloses an impedance adaptive circuit, a wireless audio transmission device and an audio system. The impedance adaptive circuit comprises an audio connection port, a sampling module, a main control module and an impedance switching module. The audio connection port is used for connecting an audio device. The main control module is used for outputting a sampling detection signal. The sampling module is used for sampling to obtain a sampling signal based on the sampling detection signal. The main control module is used for acquiring the sampling signal, determining a device type based on the sampling signal, and generating an impedance control signal based on the device type. The impedance switching module is used for outputting a corresponding impedance through the audio connection port based on the impedance control signal. The application can realize automatic switching of an output impedance to adapt to devices with different impedances, solves the problem that a wireless audio transmission device needs to manually switch the output impedance, and the output impedance switching is relatively cumbersome and prone to misoperation, and is beneficial to improving the use experience of the wireless audio transmission device.

Description

Technical Field

[0001] This invention relates to the field of audio transmission technology, and more particularly to an impedance adaptive circuit, a wireless audio transmission device, and an audio system. Background Technology

[0002] Currently, most wireless audio transmission devices on the market typically only have a single audio output interface to balance size and cost. This interface needs to be compatible with various application scenarios, such as real-time headphone monitoring, external microphone input for cameras, and recording via Lightning / Type-C adapter cables to connect to mobile devices.

[0003] Camera microphone inputs typically have a 1.5V–5V bias voltage for wireless audio transmission devices, resulting in high input impedance. If the audio signal from the wireless audio transmission device is directly output to the camera with low impedance, it can easily introduce background noise and bias voltage interference, leading to a poor signal-to-noise ratio (SNR) in the recording. Recording devices connect to the wireless audio transmission device via a 3.5mm to Lightning / Type-C recording cable. These cables usually have a 10kΩ pull-down resistor, resulting in high input impedance. If the audio signal from the wireless audio transmission device is directly output to the recording device with low impedance, it can easily introduce background noise and bias voltage interference, leading to a poor SNR in the recording. To avoid poor SNR issues between the camera and the recording device, it is necessary to set the output impedance of both the camera and the recording device to be relatively high.

[0004] Headphones are low-impedance loads (16Ω~32Ω), requiring low-impedance drive to ensure sufficient loudness and dynamic range. If high-impedance output is used, problems such as low volume and increased distortion will occur.

[0005] The output impedance of existing wireless audio transmission devices is mostly switched manually, which is cumbersome, prone to errors, and affects the user experience. Summary of the Invention

[0006] This invention provides an impedance adaptive circuit, a wireless audio transmission device, and an audio system to solve the problem that the output impedance of wireless audio transmission devices needs to be manually switched, which is cumbersome and prone to misoperation.

[0007] In a first aspect, embodiments of the present invention provide an impedance adaptive circuit, including an audio connection port, a sampling module, a main control module, and an impedance switching module; The audio port is used to connect audio devices; The output terminal of the main control module is electrically connected to the audio connection port, and the output terminal of the main control module is used to output a sampling detection signal; The input terminal of the sampling module is electrically connected to the audio connection port, and the output terminal of the sampling module is electrically connected to the sampling terminal of the main control module; the sampling module is used to sample the detection signal to obtain a sampling signal; the main control module is used to acquire the sampling signal, determine the device type based on the sampling signal, and generate an impedance control signal based on the device type; The control terminal of the main control module is electrically connected to the input terminal of the impedance switching module, and the output terminal of the impedance switching module is electrically connected to the audio connection port. The impedance switching module is used to output the corresponding impedance through the audio connection port based on the impedance control signal.

[0008] Optionally, the device type includes a first type of impedance device and a second type of impedance device; The main control module is specifically used to: generate a first impedance control signal when the device type is a first type of impedance device, and generate a second impedance control signal when the device type is a second type of impedance device; The impedance switching module is used to output a first impedance through the audio connection port based on the first impedance control signal and to output a second impedance through the audio connection port based on the second impedance control signal, wherein the first impedance is greater than the second impedance.

[0009] Optionally, the first type of impedance device includes at least one of a camera and a recording device; And / or, the second type of impedance device includes headphones.

[0010] Optionally, it also includes a first resistor, the first end of which is electrically connected to the output terminal of the main control module; The impedance switching module is used to be in a first state based on the first impedance control signal. In the first state, the second end of the first resistor is electrically connected to the audio connection port, and the output end of the main control module is disconnected from the audio connection port. The impedance switching module is used to be in a second state based on the second impedance control signal. In the second state, the output terminal of the main control module is directly electrically connected to the audio connection port, and the second end of the first resistor is disconnected from the audio connection port.

[0011] Optionally, the sampling module includes an ADC sampling circuit, which is electrically connected to the audio connection port; Before the main control module determines the device type based on the sampled signal, the impedance switching module is in the first state.

[0012] Optionally, the impedance switching module includes a switch control submodule and a switching switch; The input terminal of the switch control submodule is electrically connected to the control terminal of the main control module, the output terminal of the switch control submodule is electrically connected to the control terminal of the switching switch, and the first terminal of the switching switch is electrically connected to the audio connection port. The switch control submodule is used to control the switching switch to a first position based on the first impedance control signal. When the switching switch is in the first position, the second end of the switching switch is electrically connected to the second end of the first resistor and disconnected from the output end of the main control module. The switch control submodule is used to control the switching switch to a second position based on the second impedance control signal. The second end of the switching switch is directly electrically connected to the output end of the main control module and disconnected from the second end of the first resistor.

[0013] Optionally, the switch control submodule includes a second resistor, a third resistor, a fourth resistor, and a first transistor; The first end of the second resistor is electrically connected to the control terminal of the main control module. The second end of the second resistor is electrically connected to the base of the first transistor and the first end of the third resistor. The second end of the third resistor and the emitter of the first transistor are both grounded. The collector of the first transistor is electrically connected to the first end of the fourth resistor and the control terminal of the switching switch. The second end of the fourth resistor is electrically connected to the power supply.

[0014] Optionally, a fifth resistor may also be included; The first end of the fifth resistor is electrically connected to the audio connection port, and the second end of the fifth resistor is grounded; when the impedance switching module is in the first state, the fifth resistor and the first resistor form a voltage divider circuit.

[0015] Optionally, a first capacitor and a second capacitor may also be included; The first terminal of the first capacitor is electrically connected to the audio connection port, and the second terminal of the first capacitor is grounded. The first terminal of the second capacitor is electrically connected to the output terminal of the impedance switching module, and the second terminal of the second capacitor is electrically connected to the audio connection port. When the impedance switching module is in the first state, the first resistor, the first capacitor, and the second capacitor constitute a filter circuit.

[0016] Optionally, it also includes an insertion detection module, the input of which is electrically connected to the audio connection port. The insertion detection module is used to detect whether the audio connection port is connected to an audio device, and outputs an insertion detection signal when the audio connection port is connected to an audio device. The output terminal of the insertion detection module is electrically connected to the detection terminal of the main control module, and the main control module is used to output the sampling detection signal when the insertion detection signal is acquired.

[0017] Optionally, the audio connection port includes a first channel interface and a second channel interface; The insertion detection module includes a sixth resistor, a seventh resistor, and a first MOSFET; The first end of the sixth resistor is electrically connected to the first channel interface, and the second end of the sixth resistor is grounded; the first end of the seventh resistor is electrically connected to the second channel interface, the second end of the seventh resistor is electrically connected to the gate of the first MOS transistor, the source of the first MOS transistor is grounded, and the drain of the first MOS transistor is electrically connected to the detection terminal of the main control module. When the audio device is not connected to the audio connection port, the first channel interface and the second channel interface are shorted, and the first MOS transistor is turned off. When the audio device is connected to the audio interface, the first channel interface and the second channel interface are disconnected, and the first MOS transistor is turned on to output the insertion detection signal to the main control module.

[0018] Optionally, the insertion detection module further includes a third capacitor and an eighth resistor; The first terminal of the third capacitor is electrically connected to the second terminal of the seventh resistor, the first terminal of the eighth resistor, and the gate of the first MOS transistor, respectively. The second terminal of the third capacitor is grounded, and the second terminal of the eighth resistor is connected to the power supply. The third capacitor and the eighth resistor together form a filter circuit, which is used to filter the electrical signal transmitted to the gate of the first MOS transistor.

[0019] Optionally, the frequency range of the sampling detection signal is 28kHz-40kHz; And / or, the main control module is used to acquire the sampling signal after a preset time period following the output of the sampling detection signal.

[0020] In a second aspect, embodiments of the present invention provide a wireless audio transmission device, including the impedance adaptive circuit described in the first aspect.

[0021] Thirdly, embodiments of the present invention provide an audio system, including an audio device and the wireless audio transmission device described in the second aspect.

[0022] The technical solution of this invention, through the impedance adaptive circuit including the audio connection port, sampling module, main control module and impedance switching module, can realize automatic switching of output impedance to adapt to devices with different impedances. This solves the problem of cumbersome and error-prone output impedance switching in existing wireless audio transmission devices, and helps to improve the user experience of wireless audio transmission devices.

[0023] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A schematic diagram of an impedance adaptive circuit provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of an impedance adaptive circuit when the impedance switching module is in the first state, provided by an embodiment of the present invention. Figure 3 This is a schematic diagram of an impedance adaptive circuit when the impedance switching module is in the second state, provided by an embodiment of the present invention. Figure 4 A schematic diagram of yet another impedance adaptive circuit provided in an embodiment of the present invention; Figure 5 A schematic diagram of yet another impedance adaptive circuit provided in an embodiment of the present invention; Figure 6 A schematic diagram of yet another impedance adaptive circuit provided in an embodiment of the present invention; Figure 7 A schematic diagram of yet another impedance adaptive circuit provided in an embodiment of the present invention; Figure 8 A schematic diagram of yet another impedance adaptive circuit provided in an embodiment of the present invention; Figure 9 A schematic diagram of yet another impedance adaptive circuit provided in an embodiment of the present invention; Figure 10 This is a schematic diagram of the structure of a wireless audio transmission device provided in an embodiment of the present invention; Figure 11 This is a schematic diagram of the structure of an audio system provided in an embodiment of the present invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices. The terms "upper," "lower," "left," "right," etc., indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings and are only used to describe the relative positional relationships between components or constituent parts, and do not specifically limit the specific installation orientation of each component or constituent part.

[0028] Most wireless audio transmission devices on the market today, in order to balance size and cost, typically only have a single audio output interface. This interface needs to be compatible with multiple application scenarios, such as real-time headphone monitoring, external microphone input for cameras, and recording via Lightning / Type-C adapter cables to connect to mobile devices. Different external devices have different impedance requirements for audio signals. When switching between different devices using a single interface, impedance mismatch can easily occur, leading to signal distortion or insufficient drive, thus affecting the user experience.

[0029] To address the aforementioned issues, this embodiment improves the circuitry of the wireless audio transmission device. While retaining a single audio output interface, the circuit structure is optimized to enable it to adaptively and reliably support various external devices with different impedances, such as headphone monitoring, camera recording, and mobile terminal recording, thereby enhancing the stability and versatility of the audio output.

[0030] Figure 1 This is a schematic diagram of an impedance adaptive circuit provided in an embodiment of the present invention, with reference to... Figure 1The impedance adaptive circuit 10 in this embodiment includes an audio connection port 11, a sampling module 12, a main control module 13, and an impedance switching module 14. The audio connection port 11 is used to connect to an audio device 100. The output terminal of the main control module 13 is electrically connected to the audio connection port 11, and the output terminal of the main control module 13 is used to output a sampling detection signal. The input terminal of the sampling module 12 is electrically connected to the audio connection port 11, and the output terminal of the sampling module 12 is electrically connected to the sampling terminal of the main control module 13. The sampling module 12 is used to sample based on the sampling detection signal to obtain a sampling signal. The main control module 13 is used to acquire the sampling signal, determine the device type based on the sampling signal, and generate an impedance control signal based on the device type. The control terminal of the main control module 13 is electrically connected to the input terminal of the impedance switching module 14, and the output terminal of the impedance switching module 14 is electrically connected to the audio connection port 11. The impedance switching module 14 is used to output the corresponding impedance through the audio connection port 11 based on the impedance control signal.

[0031] It is understood that different types of audio devices 100 have different impedances. After the audio connector 11 is connected to different types of audio devices 100, if the sampling detection signal output by the main control module 13 is the same, the sampling signal of the sampling module 12 should be different. Therefore, the main control module 13 can determine the device type of the audio device 100 based on the acquired sampling signal. For example, the sampling signal acquired by the sampling module 12 can be a voltage signal. The greater the impedance of the audio device 100 connected to the audio connector 11, the greater the voltage signal acquired by the sampling module 12; the smaller the impedance of the audio device 100 connected to the audio connector 11, the smaller the voltage signal acquired by the sampling module 12. It is understood that in other embodiments, the sampling signal can also be other electrical signals, which is not limited here, but is only an example.

[0032] Understandably, in order to ensure that the audio output to the audio device 100 through the audio connector 11 does not have problems such as poor signal-to-noise ratio, low volume, and distortion, it is necessary to control the audio connector 11 to output an impedance that matches the impedance of the audio device 100. That is, when the impedance of the audio device 100 is high, the audio connector 11 should output a high impedance to the audio device 100, and when the impedance of the audio device 100 is low, the audio connector 11 should output a low impedance to the audio device 100.

[0033] The present invention, through the impedance adaptive circuit 10 including the audio connection port 11, sampling module 12, main control module 13 and impedance switching module 14, can automatically switch the output impedance according to the device type of the connected audio device 100 to adapt to audio devices 100 with different impedances. This solves the problem that the wireless audio transmission device 20 needs to manually switch the output impedance, which is cumbersome and prone to misoperation, and is conducive to improving the user experience of the wireless audio transmission device 20.

[0034] For example, in this embodiment of the invention, the main control module 13 outputs different impedance control signals to the impedance switching module 14 based on the device type. The impedance switching module 14 can output different impedances through the audio connection port 11 based on different impedance control signals, so as to achieve impedance matching between the audio connection port 11 and the audio device 100. As a feasible implementation, the device type includes a first type of impedance device and a second type of impedance device. Specifically, the main control module 13 is used to generate a first impedance control signal when the device type is a first type of impedance device and a second impedance control signal when the device type is a second type of impedance device. The impedance switching module 14 is used to output a first impedance through the audio connection port 11 based on the first impedance control signal and a second impedance through the audio connection port 11 based on the second impedance control signal, wherein the first impedance is greater than the second impedance. In this way, different impedances can be output when the device type is different, so as to match the impedance requirements of different audio devices 100.

[0035] In one feasible implementation, the first type of impedance device includes at least one of a camera and a recording device; and / or, the second type of impedance device includes headphones.

[0036] For example, cameras and recording devices have high input impedance. If a low impedance is directly output to the camera, it can easily introduce background noise and bias voltage interference, resulting in a poor signal-to-noise ratio in the recording. Headphones have low input impedance and require low impedance drive to ensure sufficient loudness and dynamic range. If a high impedance output is used, problems such as low volume and increased distortion will occur. By outputting a larger first impedance to the camera and recording device, the problem of poor signal-to-noise ratio in the recording can be effectively avoided. By outputting a smaller second impedance to the headphones, the problems of low volume and increased distortion in the headphones can be effectively avoided.

[0037] Figure 2 This is a schematic diagram of an impedance adaptive circuit when the impedance switching module is in the first state, provided by an embodiment of the present invention. Figure 3 This is a schematic diagram of an impedance adaptive circuit when the impedance switching module is in the second state, provided by an embodiment of the present invention. (Refer to...) Figure 2 and Figure 3The impedance adaptive circuit 10 in this embodiment of the invention further includes a first resistor R1, the first end of which is electrically connected to the output end of the main control module 13; the impedance switching module 14 is used to be in a first state based on the first impedance control signal, in which the second end of the first resistor R1 is electrically connected to the audio connection port 11 and the output end of the main control module 13 is disconnected from the audio connection port 11; the impedance switching module 14 is used to be in a second state based on the second impedance control signal, in which the output end of the main control module 13 is directly electrically connected to the audio connection port 11 and the second end of the first resistor R1 is disconnected from the audio connection port 11.

[0038] For example, in this embodiment of the invention, the output impedance can be switched by setting whether a first resistor R1 is connected in series between the output terminal of the main control module 13 and the audio connection port 11. Specifically, the output impedance of the audio connection port 11 with the first resistor R1 connected in series is greater than the output impedance of the audio connection port 11 without the first resistor R1 connected in series.

[0039] refer to Figure 2 and Figure 3 The impedance switching module 14 includes a switch control submodule 141 and a switching switch 142. The input terminal of the switch control submodule 141 is electrically connected to the control terminal of the main control module 13, and the output terminal of the switch control submodule 141 is electrically connected to the control terminal of the switching switch 142. The first terminal of the switching switch 142 is electrically connected to the audio connection port 11. The switch control submodule 141 is used to control the switching switch 142 to a first position based on a first impedance control signal. When the switching switch 142 is in the first position, the second terminal of the switching switch 142 is electrically connected to the second terminal of the first resistor R1 and disconnected from the output terminal of the main control module 13. The switch control submodule 141 is used to control the switching switch 142 to a second position based on a second impedance control signal. The second terminal of the switching switch 142 is directly electrically connected to the output terminal of the main control module 13 and disconnected from the second terminal of the first resistor R1.

[0040] For details, please refer to Figure 2 When the audio device 100 connected to the audio connector 11 is a Class I impedance device with high input impedance (such as a camera or recording device), the main control module 13 will generate a first impedance control signal to the input terminal of the switch control submodule 141. Then, the switch control submodule 141 will control the switch 142 to be in the first position. At this time, a first resistor R1 will be connected in series between the output terminal of the main control module 13 and the audio connector 11, so that the output impedance of the audio connector 11 is larger to match the Class I impedance device with high input impedance.

[0041] refer to Figure 3When the audio device 100 connected to the audio connector 11 is a second type of impedance device with low input impedance (such as headphones), the main control module 13 will generate a second impedance control signal to the input terminal of the switch control submodule 141. The switch control submodule 141 will then control the switch 142 to be in the first position. At this time, the first resistor R1 will not be connected in series between the output terminal of the main control module 13 and the audio connector 11, thereby making the output impedance of the audio connector 11 smaller to match the second type of impedance device with low input impedance.

[0042] Continue to refer to Figure 2 and Figure 3 The switch control submodule 141 includes a second resistor R2, a third resistor R3, a fourth resistor R4, and a first transistor Q1. The first end of the second resistor R2 is electrically connected to the control terminal of the main control module 13. The second end of the second resistor R2 is electrically connected to the base of the first transistor Q1 and the first end of the third resistor R3. The second end of the third resistor R3 and the emitter of the first transistor Q1 are both grounded. The collector of the first transistor Q1 is electrically connected to the first end of the fourth resistor R4 and the control terminal of the switch 142. The second end of the fourth resistor R4 is electrically connected to the power supply VCC.

[0043] For example, refer to Figure 2 When the audio device 100 connected to the audio connector 11 is a Class I impedance device with high input impedance (such as a camera or recording device), the first impedance control signal output by the control terminal of the main control module 13 can be low (e.g., 0V). At this time, the base of the NPN type first transistor Q1 can receive the low level through the second resistor R2, which acts as a current limiting protection, and thus the first transistor Q1 is turned off. In this way, the control terminal of the switch 142 is also low, the switch 142 is in the first position, and the first resistor R1 is connected in series between the main control module 13 and the audio connector 11 to achieve high output impedance.

[0044] refer to Figure 3 When the audio device 100 connected to the audio connector 11 is a second-class impedance device with low input impedance (e.g., headphones), the second impedance control signal output by the control terminal of the main control module 13 can be a high level (e.g., 3.3V, 5V). At this time, the base of the NPN type first transistor Q1 can receive the high level through the second resistor R2, which acts as a current limiting protection, and thus the first transistor Q1 is turned on. The switch 142 is in the second position, and the output terminal of the main control module 13 is directly connected to the audio connector 11. The first resistor R1 will not be connected in series between the output terminal of the main control module 13 and the audio connector 11, thus achieving low output impedance.

[0045] In a preferred embodiment, reference Figure 2 and Figure 3 As can be seen, the audio connector 11 includes six pins: ground reference terminal GN, right channel audio output terminal R, right channel detection terminal RN, left channel audio output terminal L, left channel detection terminal LN, and ground terminal GN, which can effectively be compatible with 3-pole / 4-pole and national standard / international standard headphones. Figure 2 and Figure 3 The right channel audio output terminal R of the audio connector 11 is electrically connected to the right audio output terminal of the main control module 13, and the left channel audio output terminal L of the audio connector 11 is electrically connected to the left audio output terminal of the main control module 13. It should be noted that the output terminals of the main control module 13 may include a right audio output terminal and a left audio output terminal. Both the right and left audio output terminals can output sampling detection signals. The right audio output terminal can also output right audio, and the left audio output terminal can also output left audio.

[0046] exist Figure 2 and Figure 3 In the impedance adaptive circuit 10 shown, there are two first resistors R1, which correspond to the right audio output terminal and the left audio output terminal respectively.

[0047] For example, refer to Figure 2 When the audio device 100 connected to the audio connector 11 is a Class I impedance device with high input impedance (e.g., a camera, recording equipment), the first impedance control signal output by the control terminal of the main control module 13 can be low (e.g., 0V). At this time, the base of the NPN type first transistor Q1 can receive this low level through the second resistor R2, which acts as a current limiting protection, and thus the first transistor Q1 is turned off. After that, the collector of the first transistor Q1 is pulled to the power supply voltage (e.g., 3.3V, 5V) through the fourth resistor R4, which is a high level. Thus, the control terminal of the switch 142 is also high, and the switch 142 is in the first position. The first resistor R1 will be connected in series between the right audio output terminal of the main control module 13 and the right channel audio output terminal R of the audio connector 11, and the first resistor R1 will also be connected in series between the left audio output terminal of the main control module 13 and the left channel audio output terminal L of the audio connector 11, so as to realize the output of high impedance to the audio device 100 connected to the audio connector 11.

[0048] refer to Figure 3When the audio device 100 connected to the audio connector 11 is a second-class impedance device with low input impedance (e.g., headphones), the second impedance control signal output by the control terminal of the main control module 13 can be high level (e.g., 3.3V, 5V). At this time, the base of the NPN type first transistor Q1 can receive the high level through the second resistor R2, which acts as a current limiting protection, and thus the first transistor Q1 is turned on. After that, the collector of the first transistor Q1 is pulled close to the ground potential, so the control terminal of the switch 142 is also low level. The switch 142 is in the second position, and the first resistor R1 will not be connected in series between the right audio output terminal of the main control module 13 and the right channel audio output terminal R of the audio connector 11, nor will the first resistor R1 be connected in series between the left audio output terminal of the main control module 13 and the left channel audio output terminal L of the audio connector 11, so as to realize the output of low impedance to the audio device 100 connected to the audio connector 11.

[0049] It should be noted that the function of the third resistor R3 is to ensure reliable turn-off of the transistor and prevent false turn-on. Specifically, when the control signal received by the base of the first transistor Q1 is low (or floating, no control signal), the third resistor R3 can pull the base potential of the first transistor Q1 to ground, ensuring that the transistor is completely turned off. Without the third resistor R3, when the control signal is floating, the base of the first transistor Q1 may be induced with interference voltage, causing the first transistor Q1 to conduct slightly, resulting in unstable switching state. At the same time, the third resistor R3 can also form a voltage divider circuit with the second resistor R2. When the control signal received by the base of the first transistor Q1 is low (or floating, no control signal), the base of the first transistor Q1 is reliably clamped at 0V.

[0050] As a feasible implementation, the sampling module 12 in this embodiment includes an ADC sampling circuit, which is electrically connected to the audio connection port 11. Before the main control module 13 determines the device type based on the sampling signal, the impedance switching module 14 is in a first state. Since the audio device connected to the audio connection port 11 is equivalent to a load, the first resistor R1 can form a voltage divider with the audio device connected to the audio connection port 11. The ADC sampling circuit, electrically connected to the audio connection port 11, can obtain the voltage divider signal, thereby detecting the impedance of the connected audio device. Therefore, the first resistor R1 is multiplexed at this time, and can be used for both high impedance output and device type detection.

[0051] It should be noted that the ADC sampling circuit in this embodiment of the invention can consist of a voltage divider circuit (which can be composed of two resistors connected in series) and an analog-to-digital converter. The voltage divider circuit first divides the acquired raw analog voltage and converts it into an analog voltage within the range of the analog-to-digital converter. Then, the analog-to-digital converter performs analog-to-digital conversion on the converted analog voltage before transmitting it to the main control module 13. In other embodiments, the ADC sampling circuit can also be an independent integrated ADC chip, which integrates a complete set of functions such as signal conditioning, reference source, and conversion circuit. The specific structure of the ADC sampling circuit is not specifically limited here; it is merely an example.

[0052] Figure 4 This is a schematic diagram of another impedance adaptive circuit provided in an embodiment of the present invention, referred to... Figure 4 The impedance adaptive circuit 10 in this embodiment of the invention also includes a fifth resistor R5; the first end of the fifth resistor R5 is electrically connected to the audio connection port 11, and the second end of the fifth resistor R5 is grounded; when the impedance switching module 14 is in the first state, the fifth resistor R5 and the first resistor R1 form a voltage divider circuit, thereby adjusting the output noise floor.

[0053] For example, Figure 4 The fifth resistor R5 shown has two parts. One is connected between the right channel audio output terminal R of the audio connector 11 and ground. When the impedance switching module 14 is in the first state, it can form a voltage divider circuit with the first resistor R1 connected between the right audio output terminal of the main control module 13 and the right channel audio output terminal L of the audio connector 11. The other is connected between the left channel audio output terminal L and ground. It can form a voltage divider circuit with the first resistor R1 connected between the left audio output terminal of the main control module 13 and the left channel audio output terminal L of the audio connector 11.

[0054] Figure 5 This is a schematic diagram of another impedance adaptive circuit provided in an embodiment of the present invention, referred to... Figure 5 The impedance adaptive circuit 10 in this embodiment of the invention further includes a first capacitor C1 and a second capacitor C2; the first end of the first capacitor C1 is electrically connected to the audio connection port 11, and the second end of the first capacitor C1 is grounded; the first end of the second capacitor C2 is electrically connected to the output terminal of the impedance switching module 14, and the second end of the second capacitor C2 is electrically connected to the audio connection port 11; when the impedance switching module 14 is in the first state, the first resistor R1, the first capacitor C1, and the second capacitor C2 constitute a filter circuit. By using the first resistor R1, the first capacitor C1, and the second capacitor C2 to form a filter circuit, the background noise is reduced and popping noise is prevented.

[0055] For example, Figure 4There are two first capacitors C1 and two second capacitors C2. One of the two first capacitors C1 is connected between the right channel audio output terminal R of the audio connector 11 and ground. One of the two second capacitors C2 is connected between the right audio output terminal of the impedance switching module 14 and the right channel audio output terminal R of the audio connector 11. When the impedance switching module 14 is in the first state, it can form a filter circuit with the first resistor R1 connected between the right audio output terminal of the main control module 13 and the right channel audio output terminal L of the audio connector 11 to achieve DC blocking and noise filtering. The other one of the two first capacitors C1 is connected between the right audio output terminal of the main control module 13 and the right channel audio output terminal L of the audio connector 11. Between the left channel audio output terminal R of the audio connector 11 and ground, the other of the two second capacitors C2 is connected between the left audio output terminal of the impedance switching module 14 and the left channel audio output terminal R of the audio connector 11. When the impedance switching module 14 is in the first state, it can form a filter circuit with the first resistor R1 connected between the right audio output terminal of the main control module 13 and the right channel audio output terminal L of the audio connector 11 to achieve the function of blocking DC and filtering noise. It can also form a voltage divider circuit with the first resistor R1 connected between the left audio output terminal of the main control module 13 and the left channel audio output terminal L of the audio connector 11.

[0056] Figure 6 This is a schematic diagram of another impedance adaptive circuit provided in an embodiment of the present invention, referred to... Figure 6 The impedance adaptive circuit 10 in this embodiment of the invention further includes an insertion detection module 15. The input terminal of the insertion detection module 15 is electrically connected to the audio connection port 11. The insertion detection module 15 is used to detect whether the audio connection port 11 is connected to the audio device 100, and outputs an insertion detection signal when the audio connection port 11 is connected to the audio device 100. The output terminal of the insertion detection module 15 is electrically connected to the detection terminal of the main control module 13. The main control module 13 is used to output a sampling detection signal when the insertion detection signal is obtained.

[0057] It is understandable that if the audio device 100 is not inserted into the audio connector 11, the main control module 13 will still output a sampling detection signal, which will cause problems such as energy waste, false triggering, and poor circuit reliability. To avoid the above situation, this embodiment of the invention provides an insertion detection module 15. The main control module 13 only outputs a sampling detection signal when the insertion detection module 15 detects that an audio device 100 is inserted into the audio connector 11, thereby reducing unnecessary power consumption and preventing energy waste. At the same time, it can also prevent the system from misjudging the insertion status of the audio device 100, improving the working stability. It can also prevent uncertain levels when the interface is floating, avoid the subsequent circuits from malfunctioning, generating noise, or overheating due to abnormal levels, and improve the working reliability of the impedance adaptive circuit 10.

[0058] Figure 7This is a schematic diagram of another impedance adaptive circuit provided in an embodiment of the present invention, referred to... Figure 7 In this embodiment of the invention, the audio connection port 11 includes a first channel interface and a second channel interface; the insertion detection module 15 includes a sixth resistor R6, a seventh resistor R7, and a first MOSFET Q2; the first end of the sixth resistor R6 is electrically connected to the first channel interface, and the second end of the sixth resistor R6 is grounded; the first end of the seventh resistor R7 is electrically connected to the second channel interface, and the second end of the seventh resistor R7 is electrically connected to the gate of the first MOSFET Q2, the source of the first MOSFET Q2 is grounded, and the drain of the first MOSFET Q2 is electrically connected to the detection terminal of the main control module 13; when the audio device 100 is not connected to the audio connection port 11, the first channel interface and the second channel interface are short-circuited, and the first MOSFET Q2 is turned off; when the audio device 100 is connected to the audio connection port 11, the first channel interface and the second channel interface are disconnected, and the first MOSFET Q2 is turned on to output an insertion detection signal to the main control module 13. In this way, when the connection status between the audio device 100 and the audio connector 11 is different, the first MOSFET Q2 will be in two different states: cut-off and conduction. The electrical signal received by the main control module 13 from the first MOSFET Q2 will also be different, thereby realizing the detection of the insertion status of the audio device 100.

[0059] exist Figure 7 In the illustrated embodiment, the first channel interface is the left channel audio output terminal L of the audio connector 11, and the second channel interface is the left channel detection terminal LN, thus allowing for compatibility with both American standard and Chinese standard interfaces. It should be noted that in other feasible embodiments, the first channel interface can also be the right channel audio output terminal R of the audio connector 11, and the second channel interface can be the right channel detection terminal RN. It should also be noted that for Chinese standard interfaces, both of the above methods are acceptable.

[0060] refer to Figure 7 When the audio device 100 is not connected to the audio interface 11, the first channel interface and the second channel interface are shorted. The gate of the first MOS transistor Q2 (e.g., an NPN type MOS transistor) is pulled down to near ground potential through the series-connected sixth resistor R6 and seventh resistor R7. The first MOS transistor Q2 is in the off state, and the main control module 13 cannot receive the insertion detection signal.

[0061] When the audio device 100 is connected to the audio interface 11, the first channel interface and the second channel interface are disconnected, the first end of the seventh resistor R7 is left floating, the gate of the first MOS transistor Q2 (e.g., an NPN MOS transistor) is at a high level, the first MOS transistor Q2 is in the conducting state, and the main control module 13 can receive the insertion detection signal.

[0062] exist Figure 7In the illustrated embodiment, the insertion detection module 15 further includes a tenth resistor R10, which is the same as the sixth resistor R6. The first end of the tenth resistor R10 is electrically connected to the right channel audio output terminal R, and the first end of the tenth resistor R10 is grounded. The tenth resistor R10 is provided to ensure that the electronic components located between the right audio output terminal of the main control module 13 and the right channel audio output terminal R of the audio connector 11 are consistent with the electronic components located between the left audio output terminal of the main control module 13 and the left channel audio output terminal L of the audio connector 11, thereby ensuring the consistency of left and right audio transmission.

[0063] It is understandable that when the first channel interface is the right channel audio output terminal R of the audio connection port 11 and the second channel interface is the right channel detection terminal RN, the first end of the tenth resistor R10 is electrically connected to the left channel audio output terminal L, and the first end of the tenth resistor R10 is grounded.

[0064] Figure 8 This is a schematic diagram of another impedance adaptive circuit provided in an embodiment of the present invention, referred to... Figure 8 The insertion detection module 15 in this embodiment further includes a third capacitor C3 and an eighth resistor R8. The first end of the third capacitor C3 is electrically connected to the second end of the seventh resistor R7, the first end of the eighth resistor R8, and the gate of the first MOSFET Q2. The second end of the third capacitor C3 is grounded, and the second end of the eighth resistor R8 is connected to the power supply VCC. The third capacitor C3 and the eighth resistor R8 form a filter circuit for filtering the electrical signal transmitted to the gate of the first MOSFET Q2. When the audio device 100 is playing music, it may be difficult to identify whether an audio device is inserted. By filtering out the audio signal, the insertion status of the audio device 100 can be accurately identified.

[0065] For example, the third capacitor C3 and the eighth resistor R8 form a filter circuit, which can not only absorb the spikes and mechanical jitters of the audio device 100 during plugging and unplugging, and prevent the first MOSFET Q2 from flipping erroneously, but also prevent the voltage of the gate of the first MOSFET Q2 from fluctuating when the main control module 13 outputs audio.

[0066] Figure 9 This is a schematic diagram of another impedance adaptive circuit provided in an embodiment of the present invention, referred to... Figure 9 The insertion detection module 15 in this embodiment of the invention further includes a current-limiting resistor R9; the first end of the current-limiting resistor R9 is electrically connected to the drain of the first MOS transistor Q2, and the second end of the current-limiting resistor R9 is electrically connected to the detection end of the main control module 13.

[0067] For example, the current-limiting resistor R9 can protect the first MOSFET Q2 and prevent it from being damaged due to overcurrent. In addition, the current-limiting resistor R9 can also prevent excessive voltage from affecting the input / output (I / O) ports of the main control module 13.

[0068] In an optional embodiment of the present invention, the frequency range of the sampling detection signal is 28kHz-40kHz; the sampling detection signal with a frequency range of 28kHz-40kHz is above the range of human hearing and does not generate audible noise, thereby not affecting the normal use of the wireless audio transmission device.

[0069] In an optional embodiment of the present invention, the main control module 13 is used to acquire the sampling signal after a preset duration of sampling detection signal output. By setting the acquisition of the sampling signal after a preset duration of sampling detection signal output, sufficient sampling time can be ensured, thereby ensuring the accuracy of the sampling signal. Preferably, the duration of the sampling detection signal can be in the range of 18ms-22ms; more preferably, the duration of the sampling detection signal is 20ms.

[0070] Based on the same inventive concept, embodiments of the present invention also provide a wireless audio transmission device. Figure 10 This is a schematic diagram of the structure of a wireless audio transmission device provided in an embodiment of the present invention, with reference to... Figure 10 The wireless audio transmission device 20 in this embodiment includes the impedance adaptive circuit 10 provided in any of the above embodiments of this invention. Therefore, the wireless audio transmission device 20 includes the technical features of the impedance adaptive circuit 10 and possesses the beneficial effects of the impedance adaptive circuit 10, as described above.

[0071] Understandably, the wireless audio transmission device could be one of a wireless microphone, lavalier microphone, or live broadcast transmitter.

[0072] Based on the same inventive concept, embodiments of the present invention also provide an audio system. Figure 11 This is a schematic diagram of the structure of an audio system provided in an embodiment of the present invention, with reference to... Figure 11 The audio system 30 in this embodiment of the invention includes an audio device 100 and a wireless audio transmission device 20 provided in the above embodiments of the invention. The wireless audio transmission device 20 provided in the above embodiments of the invention includes an impedance adaptive circuit 10 provided in any of the above embodiments. Therefore, the audio system 30 also includes the technical features of the impedance adaptive circuit 10 and possesses the beneficial effects of the impedance adaptive circuit 10. Similarities can be found in the description above.

[0073] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An impedance adaptive circuit, characterized in that, Includes audio connectors, sampling modules, main control modules, and impedance switching modules; The audio port is used to connect audio devices; The output terminal of the main control module is electrically connected to the audio connection port, and the output terminal of the main control module is used to output a sampling detection signal; The input terminal of the sampling module is electrically connected to the audio connection port, and the output terminal of the sampling module is electrically connected to the sampling terminal of the main control module; the sampling module is used to sample the detection signal to obtain a sampling signal; the main control module is used to acquire the sampling signal, determine the device type based on the sampling signal, and generate an impedance control signal based on the device type; The control terminal of the main control module is electrically connected to the input terminal of the impedance switching module, and the output terminal of the impedance switching module is electrically connected to the audio connection port. The impedance switching module is used to output the corresponding impedance through the audio connection port based on the impedance control signal.

2. The impedance adaptive circuit according to claim 1, characterized in that, The equipment types include Class I impedance equipment and Class II impedance equipment; The main control module is specifically used to: generate a first impedance control signal when the device type is a first type of impedance device, and generate a second impedance control signal when the device type is a second type of impedance device; The impedance switching module is used to output a first impedance through the audio connection port based on the first impedance control signal and to output a second impedance through the audio connection port based on the second impedance control signal, wherein the first impedance is greater than the second impedance.

3. The impedance adaptive circuit according to claim 2, characterized in that, The first type of impedance device includes at least one of a camera and a recording device; And / or, the second type of impedance device includes headphones.

4. The impedance adaptive circuit according to claim 2, characterized in that, It also includes a first resistor, the first end of which is electrically connected to the output terminal of the main control module; The impedance switching module is used to be in a first state based on the first impedance control signal. In the first state, the second end of the first resistor is electrically connected to the audio connection port, and the output end of the main control module is disconnected from the audio connection port. The impedance switching module is used to be in a second state based on the second impedance control signal. In the second state, the output terminal of the main control module is directly electrically connected to the audio connection port, and the second end of the first resistor is disconnected from the audio connection port.

5. The impedance adaptive circuit according to claim 4, characterized in that, The sampling module includes an ADC sampling circuit, which is electrically connected to the audio connection port. Before the main control module determines the device type based on the sampled signal, the impedance switching module is in the first state.

6. The impedance adaptive circuit according to claim 4, characterized in that, The impedance switching module includes a switch control submodule and a switching switch; The input terminal of the switch control submodule is electrically connected to the control terminal of the main control module, the output terminal of the switch control submodule is electrically connected to the control terminal of the switching switch, and the first terminal of the switching switch is electrically connected to the audio connection port. The switch control submodule is used to control the switching switch to a first position based on the first impedance control signal. When the switching switch is in the first position, the second end of the switching switch is electrically connected to the second end of the first resistor and disconnected from the output end of the main control module. The switch control submodule is used to control the switching switch to a second position based on the second impedance control signal. The second end of the switching switch is directly electrically connected to the output end of the main control module and disconnected from the second end of the first resistor.

7. The impedance adaptive circuit according to claim 6, characterized in that, The switch control submodule includes a second resistor, a third resistor, a fourth resistor, and a first transistor; The first end of the second resistor is electrically connected to the control terminal of the main control module. The second end of the second resistor is electrically connected to the base of the first transistor and the first end of the third resistor. The second end of the third resistor and the emitter of the first transistor are both grounded. The collector of the first transistor is electrically connected to the first end of the fourth resistor and the control terminal of the switching switch. The second end of the fourth resistor is electrically connected to the power supply.

8. The impedance adaptive circuit according to claim 4, characterized in that, It also includes a fifth resistor; The first end of the fifth resistor is electrically connected to the audio connection port, and the second end of the fifth resistor is grounded; when the impedance switching module is in the first state, the fifth resistor and the first resistor form a voltage divider circuit.

9. The impedance adaptive circuit according to claim 4, characterized in that, It also includes a first capacitor and a second capacitor; The first terminal of the first capacitor is electrically connected to the audio connection port, and the second terminal of the first capacitor is grounded. The first terminal of the second capacitor is electrically connected to the output terminal of the impedance switching module, and the second terminal of the second capacitor is electrically connected to the audio connection port. When the impedance switching module is in the first state, the first resistor, the first capacitor, and the second capacitor constitute a filter circuit.

10. The impedance adaptive circuit according to any one of claims 1 to 9, characterized in that, It also includes an insertion detection module, the input of which is electrically connected to the audio connection port. The insertion detection module is used to detect whether the audio connection port is connected to an audio device, and outputs an insertion detection signal when the audio connection port is connected to an audio device. The output terminal of the insertion detection module is electrically connected to the detection terminal of the main control module, and the main control module is used to output the sampling detection signal when the insertion detection signal is acquired.

11. The impedance adaptive circuit according to claim 10, characterized in that, The audio connection port includes a first channel interface and a second channel interface. The insertion detection module includes a sixth resistor, a seventh resistor, and a first MOSFET; The first end of the sixth resistor is electrically connected to the first channel interface, and the second end of the sixth resistor is grounded; the first end of the seventh resistor is electrically connected to the second channel interface, the second end of the seventh resistor is electrically connected to the gate of the first MOS transistor, the source of the first MOS transistor is grounded, and the drain of the first MOS transistor is electrically connected to the detection terminal of the main control module. When the audio device is not connected to the audio connection port, the first channel interface and the second channel interface are shorted, and the first MOS transistor is turned off. When the audio device is connected to the audio interface, the first channel interface and the second channel interface are disconnected, and the first MOS transistor is turned on to output the insertion detection signal to the main control module.

12. The impedance adaptive circuit according to claim 11, characterized in that, The insertion detection module also includes a third capacitor and an eighth resistor; The first terminal of the third capacitor is electrically connected to the second terminal of the seventh resistor, the first terminal of the eighth resistor, and the gate of the first MOS transistor, respectively. The second terminal of the third capacitor is grounded, and the second terminal of the eighth resistor is connected to the power supply. The third capacitor and the eighth resistor together form a filter circuit, which is used to filter the electrical signal transmitted to the gate of the first MOS transistor.

13. The impedance adaptive circuit according to any one of claims 1 to 9, characterized in that, The frequency range of the sampled detection signal is 28kHz-40kHz; And / or, the main control module is used to acquire the sampling signal after a preset time period following the output of the sampling detection signal.

14. A wireless audio transmission device, characterized in that, Includes the impedance adaptive circuit as described in any one of claims 1-13.

15. An audio system comprising an audio device and the wireless audio transmission device of claim 14.

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