Detection circuit for DC abnormity in audio signal in audio equipment

Abstract

The utility model belongs to the field of audio signal detection, and relates to a detection circuit for direct current abnormity in audio signals in audio equipment, which comprises a filter circuit, a biasing circuit, a comparison circuit, an operational amplifier protection circuit and an abnormity detection circuit, the filter circuit adopts RC filtering, the input end of the filter circuit is connected with the signal port AUDIO-IN, and the output end of the filter circuit is connected with the first input end of the comparison circuit. The comparison circuit comprises a first operational amplifier and a second operational amplifier, the anomaly detection circuit comprises a photoelectric coupler and a seventh resistor, when an audio signal output by the signal port AUDIO-IN is an audio analog signal with positive and negative fluctuations, the photoelectric coupler is not conducted, and the seventh resistor is switched off; when an audio signal output by the signal port AUDIO-IN is a direct-current positive voltage signal or a direct-current negative voltage signal, the photoelectric coupler is switched on, so that direct-current components can be effectively detected and processed under the condition that audio signal distortion is not caused.

Description

Technical Field

[0001] This application belongs to the field of audio signal detection, and particularly relates to a detection circuit for DC anomalies in audio signals in audio devices. Background Art

[0002] In audio amplification and transmission systems, due to equipment failures, manufacturing defects, or other external factors, audio signals may contain unwanted direct current (DC) components. These DC components may cause speaker damage, sound distortion, and other related problems. Therefore, being able to detect and eliminate these DC components is crucial for protecting audio devices.

[0003] In the prior art, DC component detection is performed through capacitor isolation. Specifically, a capacitor is used to block the DC component because a capacitor allows an alternating current (AC) signal to pass through while blocking the DC signal. This is the simplest protection method, but it does not provide detection of DC components or an active warning. Moreover, the capacitor distorts the audio signal, and a large-capacity capacitor is required, making it impossible to use in places where space is limited.

[0004] Therefore, how to more effectively detect DC anomalies in audio signals is a problem that needs to be solved. Summary of the Utility Model

[0005] The purpose of this application is to provide a detection circuit for DC anomalies in audio signals in audio devices to solve the problems in the prior art that a large-capacity capacitor is required to solve audio anomalies and space is limited.

[0006] The technical solution of this application is: a detection circuit for DC anomalies in audio signals in audio devices, including a filtering circuit, a biasing circuit, a comparison circuit, an operational amplifier protection circuit, and an anomaly detection circuit; the filtering circuit uses RC filtering, the input end of the filtering circuit is connected to the signal port AUDIO-IN, and the output end is connected to the first input end of the comparison circuit; the input end of the biasing circuit is connected to the positive and negative power supplies, and the output end is connected to the second input end of the comparison circuit;

[0007] The output end of the comparison circuit is connected to the input end of the anomaly detection circuit, and the output end of the anomaly detection circuit is connected to the MCU;

[0008] The comparison circuit includes a first operational amplifier and a second operational amplifier. The first input end of the first operational amplifier is the positive input end, and the second input end is the negative input end; the first input end of the second operational amplifier is the negative input end, and the second output end is the positive input end;

[0009] The abnormal detection circuit includes an optocoupler and a seventh resistor. The collector of the optocoupler is connected to the output terminal of the comparison circuit, the base is connected to pin 29 of the MCU, and the emitter is grounded. One end of the seventh resistor is connected to the power supply of the MCU, and the other end is connected to pin 29 of the MCU.

[0010] Preferably, the operational amplifier protection circuit includes an input protection circuit and an output protection circuit. The input protection circuit is provided at the input terminals of the first operational amplifier and the second operational amplifier, and the output protection circuit is provided at the output terminals of the first operational amplifier and the second operational amplifier.

[0011] The input protection circuit includes a first diode, a second diode, a third diode, and a fourth diode. The first diode and the third diode are connected in parallel and have opposite directions at both ends. The two ends of the first diode and the third diode are respectively connected to the two input terminals of the first operational amplifier. The second diode and the fourth diode are connected in parallel and have opposite directions at both ends. The two ends of the second diode and the fourth diode are respectively connected to the two input terminals of the second operational amplifier.

[0012] Preferably, the output protection circuit includes a fifth diode and a sixth diode. The positive electrode of the fifth diode is connected to the output terminal of the first operational amplifier, the positive electrode of the sixth diode is connected to the output terminal of the second operational amplifier, and a sixth resistor is connected in series between the negative electrodes of the fifth diode and the sixth diode and the collector of the optocoupler.

[0013] Preferably, the bias circuit includes a third resistor, a fourth resistor, a fifth resistor, and a tenth resistor. The third resistor, the fourth resistor, the fifth resistor, and the tenth resistor are connected in series, and one end of the third resistor is connected to the +15V power supply, and one end of the tenth resistor is connected to the -15V power supply. The ground is connected between the fourth resistor and the fifth resistor. A third capacitor is connected between the third resistor and the fourth resistor, and a fourth capacitor is connected between the fifth resistor and the tenth resistor. The other ends of the third resistor and the fourth capacitor are both grounded. The third resistor and the fourth resistor are connected to the negative input terminal of the first operational amplifier, and the fifth resistor and the tenth resistor are connected to the positive input terminal of the second operational amplifier.

[0014] Preferably, the filtering circuit includes a first resistor, a second resistor, a first capacitor, and a second capacitor. The first resistor and the second resistor are connected in series. One end of the first resistor is connected to the signal port AUDIO - IN. One end of the first capacitor and one end of the second capacitor are respectively provided at both ends of the second resistor. The other ends of the first capacitor and the second capacitor are both grounded. RC filtering is performed through the AC - passing characteristic of the capacitor, which can effectively filter AC signals.

[0015] The detection circuit for DC anomalies in an audio signal in an audio device according to the present application includes a filtering circuit, a biasing circuit, a comparison circuit, an operational amplifier protection circuit, and an anomaly detection circuit; the filtering circuit uses RC filtering, and the input end of the filtering circuit is connected to the signal port AUDIO-IN, and the output end is connected to the first input end of the comparison circuit. The comparison circuit includes a first operational amplifier and a second operational amplifier, and the anomaly detection circuit includes an optocoupler and a seventh resistor. When the audio signal output by the signal port AUDIO-IN is a positive and negative fluctuating audio analog signal, the optocoupler is not turned on. When the audio signal output by the signal port AUDIO-IN is a DC positive voltage signal or a DC negative voltage signal, the optocoupler is turned on, so that the DC component can be effectively detected and processed without causing audio signal distortion. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions provided by the present application, the drawings will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application.

[0017] Figure 1 Schematic diagram of the filtering circuit, biasing circuit, comparison circuit, and operational amplifier protection circuit of the present application;

[0018] Figure 2 Schematic diagram of the anomaly detection circuit of the present application.

[0019] 1. First resistor; 2. First capacitor; 3. Second resistor; 4. Second capacitor; 5. First operational amplifier; 6. Second operational amplifier; 7. Third resistor; 8. Fourth resistor; 9. Fifth resistor; 10. Tenth resistor; 11. Third capacitor; 12. Fourth capacitor; 13. First diode; 14. Second diode; 15. Third diode; 16. Fourth diode; 17. Fifth diode; 18. Sixth diode; 19. Sixth resistor; 20. Optocoupler; 21. Seventh resistor; 22. MCU. Detailed Embodiments

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] A detection circuit for DC anomalies in an audio signal in an audio device, as Figure 1 - Figure 2As shown in the figure, it includes a filter circuit, a bias circuit, a comparison circuit, an operational amplifier protection circuit, and an abnormal detection circuit. The filter circuit uses RC filtering. The input end of the filter circuit is connected to the signal port AUDIO-IN, and the output end is connected to the first input end of the comparison circuit. The input end of the bias circuit is connected to the positive and negative power supplies, and the output end is connected to the second input end of the comparison circuit.

[0022] The output end of the comparison circuit is connected to the input end of the abnormal detection circuit, and the output end of the abnormal detection circuit is connected to the MCU22.

[0023] The comparison circuit includes a first operational amplifier 5 and a second operational amplifier 6. The first input end of the first operational amplifier 5 is the positive input end, and the second input end is the negative input end; the first input end of the second operational amplifier 6 is the negative input end, and the second output end is the positive input end.

[0024] The operational amplifier protection circuit includes an input protection circuit and an output protection circuit. The input protection circuit is arranged at the input ends of the first operational amplifier 5 and the second operational amplifier 6, and the output protection circuit is arranged at the output ends of the first operational amplifier 5 and the second operational amplifier 6.

[0025] The abnormal detection circuit includes an optocoupler 20 and a seventh resistor 21. The collector of the optocoupler 20 is connected to the output end of the comparison circuit, the base is connected to the 29th pin of the MCU22, and the emitter is grounded. One end of the seventh resistor 21 is connected to the power supply of the MCU22, and the other end is connected to the 29th pin of the MCU22.

[0026] When the audio signal output by the signal port AUDIO-IN is a positive and negative fluctuating audio analog signal, after being filtered by the RC filter of the filter circuit, the signals fed to the positive input end of the first operational amplifier 5 and the negative input end of the second operational amplifier 6 are very weak or non-existent. The output ends of the first operational amplifier 5 and the second operational amplifier 6 are both at low level, the optocoupler 20 is not conducting, the R7 pull-up resistor provides a stable high level to the 29th pin of the MCU22, and the MCU22 recognizes it as a high level, determining that the audio is normal and not triggering the action of the DC detection circuit.

[0027] When the audio signal output by the signal port AUDIO-IN is a DC positive voltage signal, after being filtered by the RC filter of the filter circuit, the DC voltage amplitude fed to the positive input end of the first operational amplifier 5 and the negative input end of the second operational amplifier 6 is attenuated very little. The voltage amplitude at the positive input end of the first operational amplifier 5 is greater than the voltage amplitude at the negative input end of the first operational amplifier 5. The output end of the first operational amplifier 5 outputs a high level, the optocoupler 20 conducts, the base of the optocoupler 20 is grounded, and the 29th pin of the MCU22 detects a DC abnormality.

[0028] When the audio signal output from the signal port AUDIO-IN is a DC negative voltage signal, after being filtered by the RC filter circuit, the DC voltage amplitude applied to the positive input terminal of the first operational amplifier 5 and the negative input terminal of the second operational amplifier 6 is attenuated very little. The voltage amplitude at the negative input terminal of the second operational amplifier 6 is less than the voltage amplitude at the positive input terminal of the second operational amplifier 6. The output terminal of the second operational amplifier 6 is at a high level, the optocoupler 20 is turned on, the base of the optocoupler 20 is grounded, and the MCU 22 detects a DC anomaly at its pin 29. The MCU 22 triggers a warning and protection mechanism based on the DC anomaly.

[0029] Through the above design, it is possible to effectively detect and process the DC component without causing audio signal distortion, and provide an active warning or protection mechanism. At the same time, the circuit design aims to reduce the required space, making it suitable for space-constrained environments. The dependence on large-capacity capacitors is reduced, thereby reducing the space required for the circuit.

[0030] Preferably, the filter circuit includes a first resistor 1, a second resistor 3, a first capacitor 2, and a second capacitor 4. The first resistor 1 and the second resistor 3 are connected in series. One end of the first resistor 1 is connected to the signal port AUDIO-IN. One end of the first capacitor 2 and one end of the second capacitor 4 are respectively provided at both ends of the second resistor 3, and the other ends of the first capacitor 2 and the second capacitor 4 are both grounded. By using the characteristic of capacitors to conduct alternating current for RC filtering, the AC signal can be effectively filtered.

[0031] Preferably, the bias circuit includes a third resistor 7, a fourth resistor 8, a fifth resistor 9, and a tenth resistor 10. The third resistor 7, the fourth resistor 8, the fifth resistor 9, and the tenth resistor 10 are connected in series, and one end of the third resistor 7 is connected to the +15V power supply, and one end of the tenth resistor 10 is connected to the -15V power supply. A ground connection is made between the fourth resistor 8 and the fifth resistor 9. A third capacitor 11 is connected between the third resistor 7 and the fourth resistor 8, and a fourth capacitor 12 is connected between the fifth resistor 9 and the tenth resistor 10. The other ends of the third resistor 7 and the fourth capacitor 12 are both grounded. The third resistor 7 and the fourth resistor 8 provide a bias voltage for comparison by connecting to the negative input terminal of the first operational amplifier 5, and the fifth resistor 9 and the tenth resistor 10 provide a bias voltage for comparison by connecting to the positive input terminal of the second operational amplifier 6.

[0032] The input protection circuit includes a first diode 13, a second diode 14, a third diode 15, and a fourth diode 16. The first diode 13 and the third diode 15 are connected in parallel and have opposite directions at both ends. The two ends of the first diode 13 and the third diode 15 are respectively connected to the two input terminals of the first operational amplifier 5. The second diode 14 and the fourth diode 16 are connected in parallel and have opposite directions at both ends. The two ends of the second diode 14 and the fourth diode 16 are respectively connected to the two input terminals of the second operational amplifier 6. The first diode 13, the second diode 14, the third diode 15, and the fourth diode 16 can prevent the operational amplifier differential pressure input to the two operational amplifiers from being too large, thereby damaging the operational amplifier.

[0033] The output protection circuit includes a fifth diode 17 and a sixth diode 18. The positive electrode of the fifth diode 17 is connected to the output terminal of the first operational amplifier 5, and the positive electrode of the sixth diode 18 is connected to the output terminal of the second operational amplifier 6. A sixth resistor 19 is connected in series between the negative electrodes of the fifth diode 17 and the sixth diode 18 and the collector of the optocoupler 20. The settings of the fifth diode 17 and the sixth diode 18 can separate each other when the output levels of the first operational amplifier 5 and the second operational amplifier 6 are different, avoiding short circuits.

[0034] In summary, the overall advantages of this application are as follows:

[0035] Accurate DC detection: By using a voltage comparator to monitor the DC component in the audio output in real time, this utility model can accurately detect the DC level exceeding the preset threshold and trigger corresponding warnings or protection measures.

[0036] Minimized audio distortion: Due to the optimized circuit design, this utility model can process the DC component without introducing additional audio distortion, which is crucial for maintaining audio quality and integrity.

[0037] Strong adaptability: The design of this utility model takes into account various environmental and application requirements, enabling it to work effectively under space-constrained conditions and increasing its applicability.

[0038] Trigger the protection mechanism: When a harmful DC component is detected, this utility model can automatically trigger the protection mechanism, such as alarming or disconnecting the audio output, thereby protecting subsequent devices from damage.

[0039] Finally, it should be noted that: in the attached drawings of the disclosed embodiments of this utility model, only the structures related to the disclosed embodiments are involved. For other structures, reference can be made to the general design. Without conflict, the same embodiment and different embodiments of this utility model can be combined with each other;

[0040] Finally, the above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A detection circuit for DC anomalies in an audio signal in an audio device, characterized in that: It includes a filter circuit, a bias circuit, a comparison circuit, an operational amplifier protection circuit and an abnormality detection circuit; the filter circuit adopts RC filtering, the input end of the filter circuit is connected to the signal port AUDIO-IN, and the output end is connected to the first input end of the comparison circuit; the input end of the bias circuit is connected to the positive and negative power supply, and the output end is connected to the second input end of the comparison circuit; The output end of the comparison circuit is connected to the input end of the abnormality detection circuit, and the output end of the abnormality detection circuit is connected to the MCU (22); The comparison circuit comprises a first operational amplifier (5) and a second operational amplifier (6); the first input end of the first operational amplifier (5) is a positive input end, and the second input end is a negative input end; the first input end of the second operational amplifier (6) is a negative input end, and the second output end is a positive input end; The abnormality detection circuit comprises a photocoupler (20) and a seventh resistor (21); the collector of the photocoupler (20) is connected to the output end of the comparison circuit, the base is connected to pin 29 of the MCU (22), and the emitter is grounded; one end of the seventh resistor (21) is connected to the power supply of the MCU (22), and the other end is connected to pin 29 of the MCU (22).

2. The detection circuit for DC anomaly in an audio signal in an audio device as claimed in claim 1, characterized in that: The operational amplifier protection circuit comprises an input protection circuit and an output protection circuit, wherein the input protection circuit is arranged at the input end of the first operational amplifier (5) and the second operational amplifier (6), and the output protection circuit is arranged at the output end of the first operational amplifier (5) and the second operational amplifier (6); The input protection circuit comprises a first diode (13), a second diode (14), a third diode (15) and a fourth diode (16); the first diode (13) and the third diode (15) are arranged in parallel and have opposite ends, and the two ends of the first diode (13) and the third diode (15) are respectively connected to the two input ends of the first operational amplifier (5); the second diode (14) and the fourth diode (16) are arranged in parallel and have opposite ends, and the two ends of the second diode (14) and the fourth diode (16) are respectively connected to the two input ends of the second operational amplifier (6).

3. The detection circuit for DC anomaly in audio signal in audio equipment as claimed in claim 2, characterized in that: The output protection circuit comprises a fifth diode (17) and a sixth diode (18); the anode of the fifth diode (17) is connected to the output end of the first operational amplifier (5), the anode of the sixth diode (18) is connected to the output end of the second operational amplifier (6), and a sixth resistor (19) is connected in series between the cathodes of the fifth diode (17) and the sixth diode (18) and the collector of the photoelectric coupler (20).

4. The detection circuit for DC anomaly in an audio signal in an audio device as claimed in claim 1, characterized in that: The bias circuit comprises a third resistor (7), a fourth resistor (8), a fifth resistor (9) and a tenth resistor (10); the third resistor (7), the fourth resistor (8), the fifth resistor (9) and the tenth resistor (10) are arranged in series and one end of the third resistor (7) is connected to a +15V power supply, and one end of the tenth resistor (10) is connected to a -15V power supply; the fourth resistor (8) and the fifth resistor (9) are connected to the ground, a third capacitor (11) is connected between the third resistor (7) and the fourth resistor (8), a fourth capacitor (12) is connected between the fifth resistor (9) and the tenth resistor (10), and the other ends of the third resistor (7) and the fourth capacitor (12) are both grounded; the third resistor (7) and the fourth resistor (8) are connected to the negative input end of the first operational amplifier (5), and the fifth resistor (9) and the tenth resistor (10) are connected to the positive input end of the second operational amplifier (6).

5. The circuit for detecting DC anomalies in an audio signal in an audio device as claimed in claim 1, characterized in that: The filter circuit comprises a first resistor (1), a second resistor (3), a first capacitor (2) and a second capacitor (4); the first resistor (1) and the second resistor (3) are arranged in series, one end of the first resistor (1) is connected to the signal port AUDIO-IN, one end of the first capacitor (2) and the second capacitor (4) are respectively arranged at two ends of the second resistor (3), and the other ends of the first capacitor (2) and the second capacitor (4) are both grounded.

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