Audio switching circuit and monitoring equipment

Abstract

The utility model provides an audio switching circuit and monitoring equipment, and relates to the technical field of audio output control, the audio switching circuit comprises a main control unit circuit, a detection circuit, a switch circuit and a tail line interface; the detection input end of the detection circuit is connected with the tail line interface, and the detection output end is connected with one signal input end of the main control unit circuit; the audio output end of the main control unit circuit is connected with the tail line interface and used for being connected with the audio receiving end of the built-in audio output device, and the control end of the main control unit circuit is used for being connected with the enabling end of the built-in audio output device. The first end of the switching circuit is connected with the detection output end of the detection circuit, and the second end is grounded; when the tail line interface is connected with the external audio output device, the detection circuit inputs a first voltage change signal to the main control unit circuit, and the main control unit circuit stops enabling the built-in audio output device. The technical scheme provided by the utility model realizes the switching of the internal and external audio output devices, and can be adapted to external audio output devices with different load types.

Description

Technical Field

[0001] The utility model relates to the technical field of audio output control, in particular to an audio switching circuit and monitoring equipment. Background Art

[0002] With the development of monitoring technology, monitoring devices, such as IP Cameras (IPC), require more and more audio output functions, which can include built-in audio output devices and external audio output devices of monitoring devices. When using them, switching between different audio output devices is involved.

[0003] There are many types of external audio output devices. For example, as loads, they can include resistive loads and capacitive loads. If a corresponding audio output channel and interface are set for each type of load, the design cost and structural complexity of the monitoring device will increase. Therefore, how to use the same audio output channel and interface to adapt to external audio output devices of different load types is of great significance to reducing the design cost and structural complexity of the monitoring device, and is a technical problem that needs to be solved urgently. Utility Model Content

[0004] In view of the problems existing in the prior art, the utility model provides an audio switching circuit and a monitoring device to adapt to external audio output devices of different load types.

[0005] The utility model provides an audio switching circuit, comprising a main control unit circuit, a detection circuit, a switch circuit and a tail line interface;

[0006] The detection input end of the detection circuit is connected to the tail line interface, and the detection output end of the detection circuit is connected to a signal input end of the main control unit circuit; the tail line interface is used to connect to an external audio output device;

[0007] The audio output terminal of the main control unit circuit is connected to the tail line interface and is used to connect to the audio receiving terminal of the built-in audio output device, and the control terminal of the main control unit circuit is used to connect to the enable terminal of the built-in audio output device;

[0008] The first end of the switch circuit is connected to the detection output end of the detection circuit, and the second end of the switch circuit is connected to the ground;

[0009] The detection circuit is used for inputting a first voltage change signal to the main control unit circuit when detecting that the tail line interface is connected to the resistive external audio output device;

[0010] The switch circuit is used to connect the detection output terminal of the detection circuit to the ground when it is closed, and the detection circuit inputs the first voltage change signal to the main control unit circuit when the detection output terminal is connected to the ground;

[0011] The main control unit circuit is used to stop outputting the enable signal to the enable terminal of the built-in audio output device when receiving the first voltage change signal.

[0012] According to an audio switching circuit provided by the utility model, the detection circuit includes a voltage division detection circuit.

[0013] According to an audio switching circuit provided by the utility model, the voltage-dividing detection circuit comprises a first voltage-dividing resistor and a second voltage-dividing resistor connected in series between a power supply and a ground;

[0014] A series node of the first voltage-dividing resistor and the second voltage-dividing resistor serves as the detection input terminal and the detection output terminal of the detection circuit.

[0015] According to an audio switching circuit provided by the utility model, the switch circuit includes a first resistor and a switch;

[0016] One end of the first resistor is connected to the detection output end of the detection circuit as the first end of the switch circuit, and the other end of the first resistor is connected to the ground through the switch.

[0017] According to an audio switching circuit provided by the utility model, the switch circuit further includes a first capacitor connected between a first end of the switch circuit and ground;

[0018] The first capacitor and the first resistor form an RC filter circuit.

[0019] According to an audio switching circuit provided by the utility model, the audio switching circuit further includes an audio output circuit;

[0020] The input end of the audio output circuit is connected to the audio output end of the main control unit circuit, and the output end of the audio output circuit is connected to the tail line interface and is used to connect to the audio receiving end of the built-in audio output device;

[0021] The audio output circuit is used to filter the audio signal output by the audio output terminal.

[0022] According to an audio switching circuit provided by the utility model, the audio output circuit includes a second capacitor, a second resistor, a third resistor and a third capacitor;

[0023] One end of the second capacitor is connected to the audio output end of the main control unit circuit as the input end of the audio output circuit, the other end of the second capacitor is connected to the ground through the second resistor, and the other end of the second capacitor is connected to the ground through the third resistor and the third capacitor connected in series;

[0024] A series node of the third resistor and the third capacitor serves as an output end of the audio output circuit.

[0025] According to an audio switching circuit provided by the utility model, the audio output circuit further includes a protection diode circuit connected between an output end of the audio output circuit and ground.

[0026] According to an audio switching circuit provided by the utility model, the protection diode circuit includes a first diode and a second diode connected in reverse series;

[0027] The anode of the first diode is connected to the anode of the second diode, the cathode of the first diode is connected to the output end of the audio output circuit, and the cathode of the second diode is connected to the ground.

[0028] The utility model also provides a monitoring device, comprising a built-in audio output device and an audio switching circuit as described in any one of the above;

[0029] The audio receiving end of the built-in audio output device is connected to the audio output end of the main control unit circuit in the audio switching circuit, and the enabling end of the built-in audio output device is connected to the control end of the main control unit circuit.

[0030] The utility model provides an audio switching circuit and monitoring equipment, comprising a main control unit circuit, a detection circuit, a switch circuit and a tail line interface; the detection input end of the detection circuit is connected to the tail line interface used for connecting to an external audio output device, and the detection output end of the detection circuit is connected to a signal input end of the main control unit circuit; the audio output end of the main control unit circuit is connected to the tail line interface and used for connecting to an audio receiving end of a built-in audio output device, and the control end of the main control unit circuit is used for connecting to an enable end of the built-in audio output device; the first end of the switch circuit is connected to the detection output end of the detection circuit, and the second end of the switch circuit is connected to the ground. The detection circuit inputs a first voltage change signal to the main control unit circuit when it detects that the tail line interface is connected to a resistive external audio output device; the switch circuit is used to connect the detection output end of the detection circuit to the ground when it is closed, and the detection circuit inputs the first voltage change signal to the main control unit circuit when the detection output end is connected to the ground. In this way, when the tail line interface is connected to an external audio output device but the external audio output device is not a resistive load, the detection circuit can input the first voltage change signal to the main control unit circuit by closing the switch circuit; in this way, it can be judged whether the tail line interface is connected to the external audio output device through the first voltage change signal. When the main control unit circuit receives the first voltage change signal, it disconnects the output of the enable signal to the enable end of the built-in audio output device. At this time, the audio output end of the main control unit circuit can be connected to the external audio output device through the tail line interface, and the audio signal is output through the external audio output device, thereby realizing the switching of the built-in audio output device to the external audio output device, and can adapt to external audio output devices of different load types through the same tail line interface and audio output channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 This is one of the structural schematic diagrams of the audio switching circuit provided by the embodiment of the utility model;

[0033] Figure 2 It is a structural schematic diagram of a voltage division detection circuit in an audio switching circuit provided by an embodiment of the utility model;

[0034] Figure 3 It is a structural schematic diagram of a switch circuit in an audio switching circuit provided by an embodiment of the utility model;

[0035] Figure 4This is the second structural diagram of the audio switching circuit provided by the embodiment of the utility model;

[0036] Figure 5 It is a structural schematic diagram of an audio output circuit in an audio switching circuit provided by an embodiment of the utility model;

[0037] Figure 6 This is the third structural diagram of the audio switching circuit provided by the embodiment of the utility model;

[0038] Figure 7 It is a schematic diagram of the structure of the monitoring device provided by the embodiment of the utility model. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be described clearly and completely in conjunction with the drawings in the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0040] It should be noted that the serial numbers assigned to the objects described in the present invention, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning.

[0041] Combine the following Figure 1-Figure 6 The audio switching circuit of the utility model is described.

[0042] Figure 1 One of the structural diagrams of the audio switching circuit provided by the embodiment of the utility model is exemplarily shown, referring to Figure 1 As shown, the audio switching circuit may include a main control unit circuit 10 , a detection circuit 20 , a tail line interface 30 and a switch circuit 40 .

[0043] The detection input terminal A of the detection circuit 20 is connected to the tail line interface 30, and the detection output terminal B of the detection circuit 20 is connected to a signal input terminal of the main control unit circuit 10; the audio output terminal M of the main control unit circuit 10 is connected to the tail line interface 30 and is used to connect to the audio receiving terminal of the built-in audio output device, and the control terminal CL of the main control unit circuit 10 is used to connect to the enable terminal of the built-in audio output device; the first terminal of the switch circuit 40 is connected to the detection output terminal B of the detection circuit 20, and the second terminal of the switch circuit 40 is connected to the ground GND.

[0044] The tail line interface 30 is used to connect to an external audio output device. The detection circuit 20 is used to input a first voltage change signal to the main control unit circuit 10 when it is detected that the tail line interface 30 is connected to the external audio output device, and input a second voltage change signal to the main control unit circuit 10 when it is detected that the tail line interface 30 is disconnected from the external audio output device; the main control unit circuit 10 is used to disconnect the output of the enable signal to the enable end of the built-in audio output device when receiving the first voltage change signal, and output the enable signal to the enable end of the built-in audio output device when receiving the second voltage change signal.

[0045] For example, the external audio output device can be a resistive load. When the tail line interface 30 is not connected to the external audio output device, the voltage signal input to the main control unit circuit 10 by the detection circuit 20 through the detection output terminal B can be a high level; and when the tail line interface 30 is connected to the resistive external audio output device, the voltage signal input to the main control unit circuit 10 by the detection circuit 20 through the detection output terminal B can become a low level, and the main control unit circuit 10 can obtain this first voltage change signal from a high level to a low level. At this time, the main control unit circuit 10 turns off the enable signal of the control terminal CL, that is, does not output the enable signal to the built-in audio output device, the built-in audio output device no longer outputs the audio signal, and the audio signal output by the audio output terminal M will be output to the external audio output device through the tail line interface 30, and the audio signal is output through the external audio output device. In this way, the switching of the built-in audio output device to the resistive external audio output device is automatically realized.

[0046] After switching to the resistive external audio output device, the voltage signal input from the detection circuit 20 to the main control unit circuit 10 remains at a low level until the resistive external audio output device is disconnected from the tail line interface 30. At this time, the voltage output from the detection output terminal B of the detection circuit 20 will be restored to the high level state before the resistive external audio output device is connected. The main control unit circuit 10 can obtain the second voltage change signal from the low level to the high level, and then output the enable signal through the control terminal CL, the built-in audio output device is enabled, and the audio signal output from the audio output terminal M will be received by the audio receiving terminal of the built-in audio output device, and the built-in audio output device outputs the audio signal. In this way, the switching from the resistive external audio output device to the built-in audio output device is automatically realized.

[0047] The switch circuit 40 is used to connect the detection output terminal B of the detection circuit 20 to the ground GND when it is closed. The detection circuit 20 can input the first voltage change signal to the main control unit circuit 10 when its detection output terminal B is connected to the ground.

[0048] For example, when the tail line interface 30 is not connected to an external audio output device, the voltage signal input to the main control unit circuit 10 by the detection circuit 20 through the detection output terminal B can be a high level; when the tail line interface 30 is connected to an external audio output device, if the voltage signal at the detection output terminal B of the detection circuit 20 cannot be changed due to a false detection by the detection circuit 20 or the connected capacitive external audio output device, the voltage signal input to the main control unit circuit 10 by the detection output terminal B of the detection circuit 20 can be changed to a low level by controlling the switch circuit 40 to be closed. At this time, it is equivalent to the detection circuit 20 inputting a first voltage change signal to the main control unit circuit 10. When receiving the first voltage change signal, the main control unit circuit 10 can turn off the enable signal of the control terminal CL, that is, not output the enable signal to the built-in audio output device. The audio signal output by the audio output terminal M will be output to the external audio output device through the tail line interface 30, and the audio signal will be output through the external audio output device, thereby realizing the switching of the built-in audio output device to the external audio output device.

[0049] After switching to the capacitive external audio output device, when the capacitive external audio output device is disconnected from the tail line interface 30, its disconnection has almost no effect on the voltage currently input from the detection output terminal B to the main control unit circuit 10, that is, the voltage signal input from the detection output terminal B to the main control unit circuit 10 is kept at a low level. At this time, the detection output terminal B of the detection circuit 20 can be disconnected from the ground GND by controlling the switch circuit 40, and the voltage signal input from the detection output terminal B of the detection circuit 20 to the main control unit circuit 10 is restored to a high level state. The main control unit circuit 10 can obtain this second voltage change signal from a low level to a high level, and then output an enable signal through the control terminal CL, the built-in audio output device is enabled, and the audio signal output from the audio output terminal M will be received by the audio receiving terminal of the built-in audio output device, and the built-in audio output device outputs the audio signal. In this way, the switching from the capacitive external audio output device to the built-in audio output device is realized.

[0050] For example, the switch circuit 40 may be a physical switch, and the user may manually control the physical switch to close. Alternatively, the switch circuit 40 may be controlled to close by the main control unit circuit 10, for example, the main control unit circuit 10 may send a closing control signal to the switch circuit 40 upon receiving an instruction signal to close the switch circuit 40, and control the switch circuit 40 to close by the closing control signal.

[0051] By way of example, the main control unit circuit 10 may include a single chip microcomputer circuit, a field programmable gate array (FPGA) circuit, and the like.

[0052] The audio switching circuit provided by the embodiment of the utility model comprises a main control unit circuit, a detection circuit, a switch circuit and a tail line interface; the detection input end of the detection circuit is connected to the tail line interface used for connecting to an external audio output device, and the detection output end of the detection circuit is connected to a signal input end of the main control unit circuit; the audio output end of the main control unit circuit is connected to the tail line interface and is used to connect to the audio receiving end of the built-in audio output device, and the control end of the main control unit circuit is used to connect to the enable end of the built-in audio output device; the first end of the switch circuit is connected to the detection output end of the detection circuit, and the second end of the switch circuit is connected to the ground. The detection circuit inputs a first voltage change signal to the main control unit circuit when it detects that the tail line interface is connected to a resistive external audio output device; the switch circuit is used to connect the detection output end of the detection circuit to the ground when it is closed, and the detection circuit inputs the first voltage change signal to the main control unit circuit when the detection output end is connected to the ground. In this way, when the tail line interface is connected to an external audio output device but the external audio output device is not a resistive load, the detection circuit can input the first voltage change signal to the main control unit circuit by closing the switch circuit; in this way, it can be judged whether the tail line interface is connected to the external audio output device through the first voltage change signal. When the main control unit circuit receives the first voltage change signal, it disconnects the output of the enable signal to the enable end of the built-in audio output device. At this time, the audio output end of the main control unit circuit can be connected to the external audio output device through the tail line interface, and the audio signal is output through the external audio output device, thereby realizing the switching of the built-in audio output device to the external audio output device, and can adapt to external audio output devices of different load types through the same tail line interface and audio output channel. Moreover, the external audio output device is connected through the tail line interface, and there are no requirements for the structure and position of the external interface, which allows flexible wiring, saves design space, and has a low implementation cost.

[0053] based on Figure 1 In the audio switching circuit of the corresponding embodiment, the detection circuit 20 may optionally be a voltage-dividing detection circuit. The external audio output device may be a resistive load. After the external audio output device is connected to the tail line interface 30, its resistance value may affect the voltage-dividing ratio of the voltage-dividing detection circuit, thereby causing the voltage value of the voltage signal output from the detection output terminal B of the voltage-dividing detection circuit 20 to change, thereby generating a first voltage change signal. After the external audio output device is disconnected from the tail line interface 30, the voltage-dividing ratio of the voltage-dividing detection circuit 20 is restored to that before the external audio output device is connected. At this time, the voltage value of the voltage signal output from the detection output terminal B of the voltage-dividing detection circuit 20 changes again, thereby generating a second voltage change signal.

[0054] For example, Figure 2 FIG. 2 shows a schematic diagram of the structure of the voltage divider detection circuit, that is, a schematic diagram of the structure of the detection circuit 20, referring to FIG. Figure 2As shown, the voltage-dividing detection circuit 20 includes a first voltage-dividing resistor R21 and a second voltage-dividing resistor R22 connected in series between the power supply VDD and the ground GND. The series node of the first voltage-dividing resistor R21 and the second voltage-dividing resistor R22 serves as the detection input terminal A and the detection output terminal B of the detection circuit 20.

[0055] In an exemplary embodiment, for example, assuming that the detection circuit 20 is as follows Figure 2 In the voltage-dividing detection circuit shown, when the external audio output device connected to the tail line interface 30 is a capacitive load, its connection will not cause the voltage signal of the detection output terminal B of the detection circuit 20 to change and generate a first voltage change signal. In this case, the switching from the built-in audio output device to the external audio output device can be achieved by controlling the switch circuit 40 to be closed.

[0056] For example, Figure 3 The schematic diagram of the structure of the switch circuit provided by the embodiment of the utility model is shown. Figure 3 As shown, the switch circuit 40 may include a first resistor R1 and a switch K. One end of the first resistor R1 is connected to the detection output terminal B of the detection circuit 20 as the first end of the switch circuit 40 , and the other end of the first resistor R1 is connected to the ground GND through the switch K.

[0057] like Figure 3 As shown, in an optional embodiment, the switch circuit 40 may further include a first capacitor C1 connected between the first end of the switch circuit 40 and the ground GND. The first capacitor C1 and the first resistor R1 form an RC filter circuit, which can filter the transient abnormal voltage at the moment when the switch K is closed, prevent the interference of the transient abnormal voltage, and protect the circuit.

[0058] based on Figure 1 The audio switching circuit of the corresponding embodiment, in an exemplary embodiment, Figure 4 The second structural diagram of the audio switching circuit provided by the embodiment of the utility model is exemplarily shown. Figure 4 As shown, the audio switching circuit also includes an audio output circuit 50, the input end of the audio output circuit 50 is connected to the audio output end M of the main control unit circuit 10, and the output end E of the audio output circuit 50 is connected to the tail line interface 30 and is used to connect to the audio receiving end of the built-in audio output device.

[0059] The audio output circuit 50 is used to filter the audio signal outputted from the audio output terminal M. In this way, the quality of the outputted audio signal can be improved by filtering the audio signal.

[0060] For example, Figure 5 shows a schematic diagram of the structure of the audio output circuit, refer to Figure 5As shown, the audio output circuit 50 may include a second capacitor C2, a second resistor R2, a third resistor R3 and a third capacitor C3. One end of the second capacitor C2 is connected to the audio output terminal M of the main control unit circuit 10 as the input end of the audio output circuit 50, the other end of the second capacitor C2 is connected to the ground GND through the second resistor R2, and the other end of the second capacitor C2 is connected to the ground GND through the third resistor R3 and the third capacitor C3 connected in series; the series node of the third resistor R3 and the third capacitor C3 is connected to the tail line interface 30 as the output end E of the audio output circuit 50 and is used to connect to the audio receiving end of the built-in audio output device.

[0061] like Figure 5 As shown, in an optional embodiment, the audio output circuit 50 may further include a protection diode circuit 51 connected between the output terminal E of the audio output circuit 50 and the ground GND, and the protection diode circuit 51 may protect the circuit.

[0062] For example, the protection diode circuit 51 may include a first diode D1 and a second diode D2 connected in reverse series, the anode of the first diode D1 is connected to the anode of the second diode D2, the cathode of the first diode D1 is connected to the output terminal E of the audio output circuit 51, and the cathode of the second diode D2 is connected to the ground GND.

[0063] Based on the above embodiments, Figure 6 The third structural diagram of the audio switching circuit provided by the embodiment of the utility model is exemplarily shown. Figure 6 As shown, the detection circuit 20 is a voltage division detection circuit, and the detection output terminal B is connected to a signal input terminal AD of the main control unit circuit 10. The signal input terminal AD can be, for example, an analog-to-digital converter (ADC) input pin of the main control unit circuit 10.

[0064] When the tail line interface 30 is not connected to an external audio output device, the first voltage-dividing resistor R21 and the second voltage-dividing resistor R22 divide the power supply VDD, and input the first voltage U1 to the signal input terminal AD, and the voltage of the signal input terminal AD is stabilized at U1. In this case, the main control unit circuit 10 outputs an enable signal to the built-in audio output device through the control terminal CL, and the audio signal output by the audio output terminal M is filtered by the audio output circuit 50 and then output through the built-in audio output device. That is, when the tail line interface 30 is not connected to an external audio output device, the audio signal is output from the built-in audio output device.

[0065] If the external audio output device connected to the tail line interface 30 is a resistive load, after the external audio output device is connected to the circuit, it is equivalent to connecting a resistor in parallel to the second voltage-dividing resistor R22. At this time, the parallel resistance value between the second voltage-dividing resistor R22 and the external audio output device is less than the resistance value of the second voltage-dividing resistor R22, which makes the voltage of the detection output terminal B less than the first voltage U1, that is, the voltage input from the detection output terminal B to the signal input terminal AD changes from the first voltage U1 to the second voltage U2 less than U1, which is equivalent to the detection circuit 20 inputting a first voltage change signal in which the voltage signal changes from a high level to a low level to the signal input terminal AD of the main control unit circuit 10. When the main control unit circuit 10 detects the first voltage change signal, it can be determined that the tail line interface 30 is connected to the external audio output device. At this time, the enable signal of the control terminal CL is turned off, that is, the enable signal is not output to the built-in audio output device. The audio signal output by the audio output terminal M is filtered by the audio output circuit 50 and then output to the external audio output device through the tail line interface 30, and the audio signal is output through the external audio output device. That is, when the tail line interface 30 is connected to an external audio output device, the output device of the audio signal is switched from the built-in audio output device to the external audio output device, realizing the switching of the built-in audio output device to the external audio output device. When the external audio output device is disconnected from the tail line interface 30, the resistance value of the external audio output device connected in parallel at both ends of the second voltage-dividing resistor R22 is released, and the voltage-dividing of the second voltage-dividing resistor R22 increases, so that the voltage input to the signal input terminal AD increases from the second voltage U2 to the first voltage U1, which is equivalent to the detection circuit 20 inputting a second voltage change signal in which the voltage signal changes from a low level to a high level to the signal input terminal AD of the main control unit circuit 10. When the main control unit circuit 10 detects the second voltage change signal, it can determine that the external audio output device of the tail line interface 30 is disconnected, and at this time, the control terminal CL outputs an enable signal to the enable terminal of the built-in audio output device, and the audio signal output by the audio output terminal M is filtered by the audio output circuit 50 and output through the built-in audio output device. That is, after the external audio output device of the tail line interface 30 is disconnected, the output device of the audio signal is automatically switched from the external audio output device to the internal audio output device, thereby realizing the switching from the external audio output device to the internal audio output device.

[0066] If the external audio output device connected to the tail line interface 30 is a capacitive load, its connection has almost no effect on the voltage input from the detection output terminal B to the signal input terminal AD, that is, the voltage of the signal input terminal AD is stable at U1. In this case, the switch K can be closed. At this time, the first resistor R1 is connected in parallel to the two ends of the second voltage-dividing resistor R22 to pull down the voltage of the signal input terminal AD. The signal input terminal AD is equivalent to generating a first voltage change signal in which the voltage signal changes from a high level to a low level. The main control unit circuit 10 can switch the output device of the audio signal from the built-in audio output device to the external audio output device according to the first voltage change signal, completing the switching of the built-in audio output device to the external audio output device. When the external audio output device is disconnected from the tail line interface 30, the voltage division of the second voltage-dividing resistor R22 does not change, that is, the voltage of the signal input terminal AD is stable. In this case, the switch K can be disconnected to disconnect the first resistor R1 connected in parallel at both ends of the second voltage-dividing resistor R22 from the circuit, and the voltage divided by the second voltage-dividing resistor R22 increases accordingly. The signal input terminal AD is equivalent to generating a second voltage change signal in which a voltage signal changes from a low level to a high level. The main control unit circuit 10 can switch the output device of the audio signal from the external audio output device to the built-in audio output device according to the second voltage change signal, thereby completing the switching from the external audio output device to the built-in audio output device.

[0067] Among them, when the switch K is closed, the first resistor R1 and the first capacitor C1 form an RC filter circuit, which can filter the instantaneous abnormal voltage at the moment the switch K is closed, prevent the interference of the instantaneous abnormal voltage, and protect the circuit.

[0068] The audio switching circuit provided by the utility model can, on the one hand, determine whether an external audio output device is connected or whether the connected external audio output device is disconnected according to the change of the voltage signal output by the detection circuit, and then quickly realize the automatic switching between the built-in audio output device and the external audio output device according to the change of the voltage signal. The circuit is simple, easy to implement, and low in cost. On the other hand, compared with the solution of using the headphone jack to achieve switching, there is no need to design a specific interface, and there are no requirements for the structure and position of the interface of the external device. The wiring can be flexibly carried out through the tail line interface, which saves design space and further reduces costs. Moreover, any power amplifier device that can be connected through the tail line interface can be connected for detection, which is flexible in application and improves the user experience.

[0069] The above embodiments take an external audio output device as an example. It can be understood that, based on the concept of the present invention, multiple tail line interfaces can be expanded to connect external audio output devices. Each tail line interface has its corresponding detection circuit and switch circuit. The circuit structure of each group of tail line interfaces, detection circuits and switch circuits is the same as the circuit structure of the above embodiments. If multiple external audio output devices are connected at the same time, the external audio output device of the channel with the smallest voltage at each signal input end of the main control unit circuit after connection can be determined as the target external audio output device, and then the output device of the audio signal is switched from the built-in audio output device to the target external audio output device.

[0070] The utility model also provides a monitoring device, which may include a built-in audio output device and an audio switching circuit as described in any of the above embodiments, wherein an audio receiving end of the built-in audio output device is connected to an audio output end of a main control unit circuit in the audio switching circuit, and an enabling end of the built-in audio output device is connected to a control end of the main control unit circuit. The monitoring device can achieve the effect that can be achieved by the audio switching circuit as described in any of the above embodiments.

[0071] For example, Figure 7 The schematic diagram of the structure of the monitoring device provided by the utility model is shown as an example. Figure 7 As shown, the monitoring device may include a built-in audio output device 80 and Figure 1 The audio switching circuit of the corresponding embodiment. The audio switching circuit includes a main control unit circuit 10, a detection circuit 20 and a tail line interface 30; the audio receiving end of the built-in audio output device 80 is connected to the audio output end M of the main control unit circuit 10 in the audio switching circuit, and the enabling end of the built-in audio output device 80 is connected to the control end CL of the main control unit circuit 10.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the utility model.

Claims

1. An audio switching circuit, characterized in that: It includes a main control unit circuit, a detection circuit, a switch circuit and a tail line interface; The detection input end of the detection circuit is connected to the tail line interface, and the detection output end of the detection circuit is connected to a signal input end of the main control unit circuit; the tail line interface is used to connect to an external audio output device; The audio output terminal of the main control unit circuit is connected to the tail line interface and is used to connect to the audio receiving terminal of the built-in audio output device, and the control terminal of the main control unit circuit is used to connect to the enable terminal of the built-in audio output device; The first end of the switch circuit is connected to the detection output end of the detection circuit, and the second end of the switch circuit is connected to the ground; The detection circuit is used for inputting a first voltage change signal to the main control unit circuit when detecting that the tail line interface is connected to the resistive external audio output device; The switch circuit is used to connect the detection output terminal of the detection circuit to the ground when it is closed, and the detection circuit inputs the first voltage change signal to the main control unit circuit when the detection output terminal is connected to the ground; The main control unit circuit is used to stop outputting the enable signal to the enable terminal of the built-in audio output device when receiving the first voltage change signal.

2. The audio switching circuit according to claim 1, characterized in that: The detection circuit includes a voltage division detection circuit.

3. The audio switching circuit according to claim 2, characterized in that: The voltage-dividing detection circuit comprises a first voltage-dividing resistor and a second voltage-dividing resistor connected in series between a power supply and a ground; A series node of the first voltage-dividing resistor and the second voltage-dividing resistor serves as the detection input terminal and the detection output terminal of the detection circuit.

4. The audio switching circuit according to claim 1, characterized in that: The switch circuit includes a first resistor and a switch; One end of the first resistor is connected to the detection output end of the detection circuit as the first end of the switch circuit, and the other end of the first resistor is connected to the ground through the switch.

5. The audio switching circuit according to claim 4, characterized in that: The switch circuit further includes a first capacitor connected between a first terminal of the switch circuit and ground; The first capacitor and the first resistor form an RC filter circuit.

6. The audio switching circuit according to any one of claims 1 to 5, characterized in that: The audio switching circuit also includes an audio output circuit; The input end of the audio output circuit is connected to the audio output end of the main control unit circuit, and the output end of the audio output circuit is connected to the tail line interface and is used to connect to the audio receiving end of the built-in audio output device; The audio output circuit is used to filter the audio signal output by the audio output terminal.

7. The audio switching circuit according to claim 6, characterized in that: The audio output circuit includes a second capacitor, a second resistor, a third resistor and a third capacitor; One end of the second capacitor is connected to the audio output end of the main control unit circuit as the input end of the audio output circuit, the other end of the second capacitor is connected to the ground through the second resistor, and the other end of the second capacitor is connected to the ground through the third resistor and the third capacitor connected in series; A series node of the third resistor and the third capacitor serves as an output end of the audio output circuit.

8. The audio switching circuit according to claim 7, characterized in that: The audio output circuit further includes a protection diode circuit connected between an output terminal of the audio output circuit and ground.

9. The audio switching circuit according to claim 8, characterized in that: The protection diode circuit comprises a first diode and a second diode connected in series in reverse order; The anode of the first diode is connected to the anode of the second diode, the cathode of the first diode is connected to the output end of the audio output circuit, and the cathode of the second diode is connected to the ground.

10. A monitoring device, characterized in that: comprising a built-in audio output device and an audio switching circuit as claimed in any one of claims 1 to 9; The audio receiving end of the built-in audio output device is connected to the audio output end of the main control unit circuit in the audio switching circuit, and the enabling end of the built-in audio output device is connected to the control end of the main control unit circuit.

Images