A speaker open circuit detection circuit

Abstract

The invention relates to the technical field of open circuit detection, and provides a loudspeaker open circuit detection circuit. Half-bridge driving circuits are added at both ends of the loudspeaker. Under the premise that the main circuit power supply is disconnected (that is, after the main control module disconnects the driving power supply of the digital-to-analog conversion module and the power amplifier module), the main control module is commanded to control the sampling detection circuit to supply power to the loudspeaker. A sampling resistor is arranged at the bottom end of the half-bridge driving circuit. The voltage value on the sampling resistor is collected by the detection circuit to obtain the sampling voltage, and whether the loudspeaker is open circuited or not is judged according to a preset open circuit judgment logic. Then, the open circuit detection result is sent to an on-board diagnostic instrument through a CAN BUS module, so as to inform the car owner or a 4S shop to replace the faulty loudspeaker, thereby further improving the service quality of the on-board loudspeaker.

Description

Technical Field

[0001] The present invention relates to the technical field of open circuit detection, and in particular to a loudspeaker open circuit detection circuit. Background Art

[0002] The alarm sound of the on-board LCD instrument is basically emitted by the on-board speaker. However, since the speaker needs to realize the audio output of the whole vehicle, and the environment of the whole vehicle is relatively complex, the alarm sound will be cut off and cannot be accurately emitted. At the same time, due to the lack of targeted diagnostic circuits, users cannot confirm whether the alarm sound is cut off due to fatigue and disconnection of the speaker itself; or because the bus did not receive the alarm message; or the output of the op amp driving the speaker is damaged; or the I2S decoding chip is damaged. Therefore, it is impossible to locate the speaker fault at all, and disassembly analysis is required. However, this inspection method of disassembly analysis is not conducive to after-sales return analysis and service. The open circuit diagnosis on the market is currently integrated in the operational amplifier IC. The cost of this circuit structure is relatively high, which is not conducive to the promotion and use of the project. In summary, the existing speaker fault detection methods have the following difficulties:

[0003] 1. The price of the computational decoding chip with open circuit detection is high, which leads to high equipment cost and is not conducive to market promotion;

[0004] 2. Unable to accurately locate the fault, for example, unable to determine whether it is an open circuit in the speaker or the operational amplifier, or a decoding chip failure or other failure. Summary of the invention

[0005] The invention provides a loudspeaker open circuit detection circuit, which solves the technical problem that the prior art cannot accurately detect the loudspeaker open circuit fault.

[0006] In order to solve the above technical problems, the present invention provides a loudspeaker open circuit detection circuit, comprising: a main control module and a sampling detection circuit connected thereto; the sampling detection circuit is connected at both ends of the loudspeaker, and comprises a half-bridge driving circuit and a detection circuit connected to each other; the signal output end of the main control module comprises a first signal output end, a second signal output end and a signal output end;

[0007] The main control module is used to output a driving instruction to the sampling detection circuit through the first signal output terminal and the second signal output terminal;

[0008] The half-bridge driving circuit is used for providing a driving current to the speaker in a non-driving state in response to the driving instruction;

[0009] The detection circuit is used to collect the circuit voltage on the driving circuit to obtain the sampled voltage;

[0010] The main control module is also used to obtain an open circuit detection result according to the sampled voltage fed back from the signal output terminal.

[0011] This basic solution sets up a sampling detection circuit including a half-bridge driving circuit and a detection circuit, so that the speaker can be directly driven when performing speaker fault detection; during the driving process, the main control module can collect the corresponding sampling voltage from the signal output end and obtain the corresponding open circuit detection result, which can accurately determine whether the speaker is open or not, achieve accurate positioning of the fault, and improve the maintenance efficiency of the equipment.

[0012] In a further embodiment, the half-bridge driving circuit includes a first resistor, a second resistor, a third resistor, a first switch tube, and a second switch tube;

[0013] The first resistor is connected to the first signal output end, and the other end is connected to one end of the speaker through the first switch tube; one end of the second resistor is connected to the second signal output end, and the other end is connected to the other end of the speaker through the second switch tube and the third resistor;

[0014] The third resistor is a sampling resistor.

[0015] In a further embodiment, the detection circuit includes a fourth resistor and a first capacitor; one end of the fourth resistor is connected to the other end of the speaker, and the other end is grounded through the first capacitor and connected to the signal output end.

[0016] This solution sets up a half-bridge drive circuit and a detection circuit connected to each other to form a sampling detection circuit, and uses the switching function and signal amplification function of the transistor in the half-bridge drive circuit to provide a driving current to the speaker in a non-driven state, so that the speaker enters a detection working state;

[0017] A sampling resistor is set in series with the speaker in the detection circuit, and the voltage of the sampling resistor is collected to obtain a sampling voltage. When the speaker is open-circuited, its internal resistance tends to infinity, and the loop current tends to infinitesimal. Therefore, the sampling voltage divided by the sampling resistor will also tend to infinitesimal (i.e., low level). When the speaker is not open-circuited, the sampling voltage can be calculated based on the resistance ratio of the sampling resistor to the internal resistance of the speaker. Therefore, whether the speaker is open-circuited can be judged based on the voltage value of the sampling voltage.

[0018] The fourth resistor and the first capacitor are further provided to perform voltage filtering, so as to avoid signal interference and further improve the accuracy of signal acquisition, that is, to improve the accuracy of speaker open circuit detection.

[0019] In a further implementation, the first switch tube is a PNP transistor or a PNP MOS tube; the second switch tube is an NPN transistor or an NPN MOS tube.

[0020] The resistance values ​​of the first resistor and the second resistor are equal; the resistance value of the third resistor is much larger than the internal resistance of the speaker;

[0021] When the speaker is open-circuited, the resistance of the speaker approaches infinity, so the sampled voltage obtained by the third resistor will be at a low level;

[0022] When the speaker works normally, the resistance of the third resistor is much greater than the internal resistance of the speaker, so the sampling voltage divided by the third resistor will be a high level.

[0023] In this scheme, a first resistor and a second resistor with equal resistance are set at the base of the first switch tube and the second switch tube as current limiting resistors of the detection circuit, which can effectively prevent the driving current of the base of the switch tube from being too large and damaging the main control module; a third resistor with a resistance much larger than the internal resistance of the speaker is set as a sampling resistor, which can ensure that the voltage divided by the sampling resistor when the speaker is working normally is large enough (i.e., high level) to be distinguished from the sampling voltage on the sampling resistor when the circuit is equivalent to a circuit break when the speaker fails (i.e., low level); so that the main control module can directly determine whether the speaker is open or not based on the sampling voltage.

[0024] The present invention also includes a digital-to-analog conversion module and a power amplification module connected in sequence between the main control module and the speaker; and a storage module and a data connection module connected to the main control module;

[0025] The digital-to-analog conversion module is used to convert the control instruction output by the main control module from a digital signal to an analog signal;

[0026] The power amplification module is used to amplify the analog signal to a preset power to drive the speaker;

[0027] The storage module is used to preset the open circuit judgment logic and play the material;

[0028] The data connection module is used to output the user's diagnostic command to the main control module;

[0029] The main control module is used to obtain an open circuit detection result according to the preset open circuit judgment logic and the sampled voltage.

[0030] In a further embodiment, the data connection module is a CAN BUS module; the storage module is a NorFlash storage; and the main control module is an MCU.

[0031] In a further implementation scheme, the preset open circuit judgment logic is: when the sampling voltage is at a low level, it is judged that the speaker is open circuit; when the sampling voltage is at a high level, it is judged that the speaker is working normally.

[0032] This basic solution adds a half-bridge drive circuit at both ends of the speaker. Under the premise that the main circuit power supply is disconnected (that is, after the main control module disconnects the driving power supply of the digital-to-analog conversion module and the power amplifier module), the main control module is commanded to control the sampling detection circuit to supply power to the speaker. A sampling resistor is set at the bottom end of the half-bridge drive circuit, and the detection circuit is used to collect the voltage value on the sampling resistor to obtain the sampling voltage, and judge whether the speaker is open according to the preset open circuit judgment logic; then the open circuit detection result is sent to the on-board diagnostic instrument through the CAN BUS module, informing the car owner or 4S shop to replace the faulty speaker, thereby further improving the service quality of the on-board speaker. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a system framework diagram of a loudspeaker open circuit detection circuit provided by an embodiment of the present invention;

[0034] Figure 2 The embodiment of the present invention provides Figure 1 Hardware circuit diagram of the sampling detection circuit.

[0035] Among them: main control module 1, sampling detection circuit 2, half-bridge driving circuit 21, detection circuit 22; digital-to-analog conversion module 3, power amplifier module 4, storage module 5, data connection module 6, speaker 7;

[0036] And: a first resistor R1 to a fourth resistor R4, a first switch tube Q1, a second switch tube Q2, a first capacitor C1; a first signal output terminal Ctrol1, a second signal output terminal Ctrol2, and a signal output terminal IO-FB. DETAILED DESCRIPTION

[0037] The following specifically illustrates the implementation mode of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0038] An embodiment of the present invention provides a speaker open circuit detection circuit, such as Figure 1 , Figure 2 As shown, in this embodiment, it includes: a main control module 1 and a sampling detection circuit 2 connected thereto; the sampling detection circuit 2 is connected to both ends of the speaker 7, including a half-bridge driving circuit 21 and a detection circuit 22 connected to each other, and the main control module 1 includes a first signal output terminal IO-FBCtrol1, a second signal output terminal IO-FBCtrol2 and a signal output terminal IO-FB;

[0039] The main control module 1 is used to output a driving instruction to the sampling detection circuit 2 through the first signal output terminal IO-FBCtrol1 and the second signal output terminal IO-FBCtrol2;

[0040] The half-bridge driving circuit 21 is used for responding to the driving instruction to provide a driving current to the speaker 7 in a non-driving state;

[0041] The detection circuit 22 is used to collect the circuit voltage on the driving circuit to obtain the sampled voltage;

[0042] The main control module 1 is further used to obtain an open circuit detection result according to a sampled voltage fed back from the signal output terminal IO-FB.

[0043] The embodiment of the present invention is provided with a sampling detection circuit 2 including a half-bridge driving circuit 21 and a detection circuit 22 connected to each other, so that the speaker 7 can be directly driven when the speaker 7 fault detection is performed; during the driving process, the main control module 1 can collect the corresponding sampling voltage from the signal output terminal IO-FB and obtain the corresponding open circuit detection result, and can accurately determine whether the speaker 7 is open circuit or not, realize accurate positioning of the fault, and improve the maintenance efficiency of the equipment.

[0044] In this embodiment, the half-bridge driving circuit 21 includes a first resistor R1, a second resistor R2, a third resistor R3, a first switch tube Q1 and a second switch tube Q2;

[0045] The first resistor R1 is connected to the first signal output terminal IO-FBCtrol1, and the other end is connected to one end of the speaker through the first switch tube Q1; one end of the second resistor R2 is connected to the second signal output terminal IO-FBCtrol2, and the other end is connected to the other end of the speaker through the second switch tube Q2 and the third resistor R3;

[0046] The third resistor R3 is a sampling resistor. In the present embodiment, its resistance value is preferably 1K ohm, which can ensure that the driving current of the speaker 7 driving circuit is as small as possible, and will not affect the selection of the first switch tube Q1 and the second switch tube Q2, thereby further reducing the cost.

[0047] In this embodiment, the detection circuit 22 includes a fourth resistor R4 and a first capacitor C1; one end of the fourth resistor R4 is connected to the other end of the speaker, and the other end is grounded through the first capacitor C1 and connected to the signal output terminal IO-FB.

[0048] In this embodiment, the first switch tube Q1 includes but is not limited to a PNP transistor and a PNP MOS tube; the second switch tube Q2 includes but is not limited to an NPN transistor and an NPN MOS tube.

[0049] Preferably, the first switch tube Q1 is a PNP type transistor with a model number of BC807-40, and its maximum driving current can reach 500mA. At this time, the base of the first switch tube Q1 is connected to the main control module 1, the emitter is connected to the power supply, and the collector is connected to one end of the speaker 7; the second switch tube Q2 is an NPN type transistor with a model number of BC817-40, and its maximum driving current can reach 500mA. At this time, the base of the second switch tube Q2 is connected to the main control module 1, the emitter is grounded, and the collector is connected to the third resistor R3.

[0050] The resistance values ​​of the first resistor R1 and the second resistor R2 are equal; the resistance value of the third resistor R3 is much larger than the internal resistance of the speaker 7 .

[0051] In this embodiment, the resistance of the first resistor R1 and the second resistor R2 is preferably 4.7K ohms, and the resistance ratio of the third resistor R3 to the internal resistance of the speaker 7 is at least 20 times;

[0052] When the speaker 7 is open, the resistance of the speaker 7 approaches infinity, so the sampling voltage obtained by the third resistor R3 will be at a low level;

[0053] When the speaker 7 works normally, the resistance of the third resistor R3 is much greater than the internal resistance of the speaker 7, so the sampling voltage divided by the third resistor R3 will be a high level.

[0054] This embodiment:

[0055] A half-bridge driving circuit 21 and a detection circuit 22 connected to each other are arranged to form a sampling detection circuit 2, and a switching function and a signal amplification function of the transistor in the half-bridge driving circuit 21 are utilized to provide a driving current to the speaker 7 in a non-driving state, so that the speaker 7 enters a detection working state;

[0056] A sampling resistor connected in series with the speaker 7 is provided in the detection circuit 22, and a voltage is collected on the sampling resistor to obtain a sampling voltage. When the speaker 7 is open-circuited, its internal resistance tends to infinity, and the loop current tends to infinitesimal. Therefore, the sampling voltage obtained by the sampling resistor will also tend to infinitesimal (i.e., a low level). When the speaker 7 is not open-circuited, the sampling voltage can be calculated based on the resistance ratio of the sampling resistor to the internal resistance of the speaker 7. Therefore, whether the speaker 7 is open-circuited can be determined based on the voltage value of the sampling voltage.

[0057] The fourth resistor R4 and the first capacitor C1 are further provided to perform voltage filtering, so as to avoid signal interference and further improve the accuracy of collecting signals, that is, to improve the accuracy of open circuit detection of the speaker 7 .

[0058] In this embodiment, the resistance value of the fourth resistor R4 is preferably 10K ohms, and the capacitance value of the first capacitor C1 is preferably 10Nf (nanofarad).

[0059] In this embodiment, a first resistor R1 and a second resistor R2 with equal resistance are set at the base of the first switch tube Q1 and the second switch tube Q2 as current limiting resistors of the detection circuit, which can effectively prevent the driving current of the base of the switch tube from being too large and damaging the main control module 1; a third resistor R3 with a resistance much larger than the internal resistance of the speaker 7 is set as a sampling resistor, which can ensure that the voltage divided by the sampling resistor when the speaker 7 is working normally is large enough (i.e., high level) and can be distinguished from the sampling voltage on the sampling resistor when the circuit is equivalent to an open circuit when the speaker 7 fails (i.e., low level); so that the main control module 1 can directly determine whether the speaker 7 is open circuit or not according to the sampling voltage.

[0060] The embodiment of the present invention further comprises a digital-to-analog conversion module 3 and a power amplification module 4 which are sequentially connected between the main control module 1 and the speaker 7; and a storage module 5 and a data connection module 6 which are connected to the main control module 1;

[0061] The digital-to-analog conversion module 3 is used to convert the control instructions output by the main control module 1 from digital signals to analog signals;

[0062] The power amplifier module 4 is used to amplify the analog signal to a preset power to drive the speaker 7;

[0063] The storage module 5 is used to preset the open circuit judgment logic and play the material;

[0064] The data connection module 6 is used to output the user's diagnostic command to the main control module 1;

[0065] The main control module 1 is used to obtain an open circuit detection result according to a preset open circuit judgment logic and a sampled voltage.

[0066] The data connection module 6 is a CAN BUS module; the storage module 5 is a Nor Flash storage; and the main control module 1 is an MCU.

[0067] In this embodiment, the preset open circuit judgment logic is: when the sampling voltage is at a low level, it is judged that the speaker 7 is open circuit; when the sampling voltage is at a high level, it is judged that the speaker 7 is working normally.

[0068] In this embodiment, the open circuit detection principle of the speaker 7 is as follows:

[0069] When the speaker 7 is detected, the data connection module 6 outputs the user's diagnostic command to the main control module 1. At this time, the main control module 1 responds to the diagnostic command and shuts off the I2S signal output to the digital-to-analog conversion module 3, that is, disconnects the drive circuit of the main control module 1-data connection module 6-power amplifier module 4-speaker 7.

[0070] Subsequently, the main control module 1 controls the first signal output terminal Ctrol1 to output a high level and the second signal output terminal Ctrol2 to output a low level, so that the first switch tube Q1 is turned on, the second switch tube Q2 is turned on, and the third resistor R3 is grounded, that is, the drive circuit of the speaker 7 is turned on.

[0071] At this time, the main control module 1 collects the voltage obtained on the third resistor R3 through the signal output terminal IO-FB, that is, the sampling voltage. The main control module 1 determines that the speaker 7 is open when the sampling voltage is low level and determines that the speaker 7 is working normally when the sampling voltage is high level according to the preset open circuit judgment logic.

[0072] Finally, the open circuit detection result (whether the speaker is open circuit or not) is sent to the on-board diagnostic instrument through the CAN BUS module, prompting the inspection personnel to perform relevant fault repairs.

[0073] In the embodiment of the present invention, a half-bridge driving circuit 21 is added at both ends of the speaker 7. Under the premise that the main circuit power supply is disconnected (that is, after the main control module 1 disconnects the driving power supply of the digital-to-analog conversion module 3 and the power amplifier module 4), the main control module 1 is commanded to control the sampling detection circuit 2 to supply power to the speaker 7. A sampling resistor is set at the bottom end of the half-bridge driving circuit 21, and the voltage value on the sampling resistor is collected by the detection circuit 22 to obtain the sampling voltage, and whether the speaker 7 is open circuited is determined according to the preset open circuit judgment logic; and then the open circuit detection result is sent to the on-board diagnostic instrument through the CAN BUS module, so as to inform the car owner or the 4S shop to replace the faulty speaker 7, thereby further improving the service quality of the on-board speaker 7.

[0074] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A speaker open circuit detection circuit, characterized in that: include: A main control module and a sampling detection circuit connected thereto; the sampling detection circuit is connected to both ends of the speaker, and includes a half-bridge drive circuit and a detection circuit connected to each other; the main control module includes a first signal output terminal, a second signal output terminal and a signal output terminal; The main control module is used to output a driving instruction to the sampling detection circuit through the first signal output terminal and the second signal output terminal; The half-bridge driving circuit is used for providing a driving current to the speaker in a non-driving state in response to the driving instruction; The detection circuit is used to collect the circuit voltage on the driving circuit to obtain the sampled voltage; The main control module is also used to obtain an open circuit detection result according to the sampled voltage fed back from the signal output terminal; The half-bridge driving circuit comprises a first resistor, a second resistor, a third resistor, a first switch tube and a second switch tube; The first resistor is connected to the first signal output end, and the other end is connected to one end of the speaker through the first switch tube; one end of the second resistor is connected to the second signal output end, and the other end is connected to the other end of the speaker through the second switch tube and the third resistor; The third resistor is a sampling resistor; The resistance of the third resistor is much greater than the internal resistance of the speaker; The detection circuit includes a fourth resistor and a first capacitor; one end of the fourth resistor is connected to the other end of the speaker, and the other end is grounded through the first capacitor and connected to the signal output end.

2. A speaker open circuit detection circuit as claimed in claim 1, characterized in that: The first switch tube is a PNP transistor or a PNP MOS tube; the second switch tube is an NPN transistor or an NPN MOS tube.

3. A speaker open circuit detection circuit as claimed in claim 1, characterized in that: The first resistor and the second resistor have equal resistance values; When the speaker is open-circuited, the resistance of the speaker approaches infinity, so the sampled voltage obtained by the third resistor will be at a low level; When the speaker works normally, the resistance of the third resistor is much greater than the internal resistance of the speaker, so the sampling voltage divided by the third resistor will be a high level.

4. A speaker open circuit detection circuit as claimed in claim 1, characterized in that: It also includes a digital-to-analog conversion module and a power amplification module connected in sequence between the main control module and the speaker; and a storage module and a data connection module connected to the main control module; The digital-to-analog conversion module is used to convert the control instruction output by the main control module from a digital signal to an analog signal; The power amplification module is used to amplify the analog signal to a preset power to drive the speaker; The storage module is used to preset the open circuit judgment logic and play the material; The data connection module is used to output the user's diagnostic command to the main control module; The main control module is used to obtain an open circuit detection result according to the preset open circuit judgment logic and the sampled voltage.

5. A speaker open circuit detection circuit as claimed in claim 4, characterized in that: The data connection module is a CAN BUS module; the storage module is a Nor Flash storage; and the main control module is an MCU.

6. A speaker open circuit detection circuit as claimed in claim 4, characterized in that: The preset open circuit judgment logic is: when the sampling voltage is at a low level, it is judged that the speaker is open circuit; when the sampling voltage is at a high level, it is judged that the speaker is working normally.

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