Car audio system and method for detecting open circuits in speakers thereof

Abstract

A car audio system and its speaker open circuit detection method. The car audio system includes a power amplifier for driving a car speaker electrically connected thereto, a control module used to control the power amplifier and having an output port and an input port, and an open circuit detection circuit having a first connection port and a second connection port used to electrically connect to two sets of leads of the speaker, respectively, the open circuit detection circuit further includes a switch circuit, the switch circuit is connected between the output port and the first connection port of the control module, and is controlled by a control signal from the output port to make the output port and the first connection port conductive or disconnected, the input port and the second connection port of the control module are respectively electrically connected to a node, the node has access to a voltage, the control module is used to enable the open circuit detection circuit through the output port, and can judge whether the speaker is in an open circuit state according to the signal received from the input port. The present invention can realize the open circuit detection of the speaker at a lower cost.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This disclosure claims priority to a Chinese patent application with application number CN202U03013728, filed on March 22, 2021.

[0002] The present invention relates to the field of audio, and more particularly to a method for detecting open circuits in car audio systems and their speakers. [Background technology]

[0003] At present, the power amplifier chip provides the diagnosis and protection function of speaker open circuit and short circuit, and this type of power amplifier chip is expensive and has a high cost. However, in the car audio system, due to the cost consideration, the car power amplifier chip used in the car audio system does not have the function of diagnosing the speaker open circuit. When selecting this type of power amplifier chip, in order to detect whether the vehicle has a speaker installed or whether the speaker can be accurately accessed, it is necessary to add a speaker open circuit detection circuit and system on the mass-produced product to complete this function and determine whether the speaker is in an open circuit state, and the speaker open circuit refers to the speaker not being installed or the speaker being installed but not accurately accessible. Summary of the Invention [Problem to be solved by the invention]

[0004] In response to the above problems, one object of the present invention is to provide a car audio system that can realize open circuit detection of speakers in the car audio system at a lower cost.

[0005] Another object of the present invention is to provide a method for detecting an open circuit in a speaker of a car audio system, which can realize the open circuit detection in a speaker of a car audio system at a lower cost. [Means for solving the problem]

[0006] According to a first aspect of the present invention, a car audio system includes: A power amplifier to drive the car speakers electrically connected to it, a control module having an output port and an input port for controlling the power amplifier; The car audio system further includes an open circuit detection circuit, which has a first connection port and a second connection port, one of the first connection port and the second connection port being electrically connected to a positive lead of the car speaker, and the other of the first connection port and the second connection port being electrically connected to a negative lead of the car speaker; The open circuit detection circuit includes a switch circuit, the switch circuit being connected between the output port of the control module and the first connection port, and being controlled by a control signal from the output port to connect or disconnect the output port and the first connection port; the input port of the control module and the second connection port are each electrically connected to a node, the node having access to a voltage; The control module is used to enable the open circuit detection circuit via the output port so as to determine whether a speaker is in an open circuit condition according to a signal received from the input port.

[0007] In this specification, "speaker open circuit" refers to a car speaker that is not installed or a car speaker that is installed but cannot be properly accessed, for example, not properly connected to a power amplifier.

[0008] In one embodiment, the switch circuit includes a transistor, a base electrode of the transistor being electrically connected to the output port, a collector electrode of the transistor being electrically connected to the first connection port, and an emitter of the transistor being grounded. Optionally, the transistor is an NPN type transistor.

[0009] In one embodiment, the switch circuit further includes a first resistor and a second resistor, the first resistor being electrically connected between the output port and a base electrode of the transistor, one end of the second resistor being electrically connected to a midpoint between the first resistor and the base electrode of the transistor, and the other end of the second resistor being electrically connected to a collector electrode of the transistor.

[0010] In one embodiment, the first resistor, the second resistor and the transistor collectively form a switch circuit.

[0011] In one embodiment, the open circuit detection circuit further includes a third resistor connected between the switch circuit and the first connection port, the third resistor being used for current limiting.

[0012] In one embodiment, the node is electrically connected to a power supply so that the voltage is accessible.

[0013] In an embodiment, the open circuit detection circuit further includes a fourth resistor at a level for pulling up and transporting to an IO port, the fourth resistor being electrically connected between the power supply end and the node.

[0014] In one embodiment, the open circuit detection circuit further includes a diode for preventing a power amplifier voltage from reacting to the control module, the diode being electrically connected between the second connection port and the input port.

[0015] In one embodiment, the open circuit detection circuit further includes a capacitor, one end of the capacitor being electrically connected to a midpoint between the second connection port and the input port, and the other end of the capacitor being grounded.

[0016] In one embodiment, the power amplifier is a BTL power amplifier, and / or the control module is a power amplifier chip, the output port and the input port are respectively IO ports of the power amplifier chip, and / or the speaker is a speaker with an impedance range of 2-8Ω.

[0017] According to a second aspect of the present invention, there is provided an open circuit detection circuit for a car audio system, the open circuit detection circuit having a first connection port and a second connection port, one of the first connection port and the second connection port being used for electrically connecting to a positive lead of a car speaker, and the other of the first connection port and the second connection port being used for electrically connecting to a negative lead of the car speaker; the open circuit detection circuit includes a switch circuit, the switch circuit being connected between an output port of a control module of a power amplifier and the first connection port, and being controlled by a control signal from the output port to connect or disconnect the output port and the first connection port; The second connection port is used to electrically connect to an input port of the control module and to a node for accessing a voltage.

[0018] In an embodiment, the switch circuit includes a transistor, a base electrode of the transistor is electrically connected to the output port, a collector electrode of the transistor is electrically connected to the first connection port, and an emitter of the transistor is grounded.

[0019] In an embodiment, the switch circuit further includes a first resistor and a second resistor, the first resistor being electrically connected between the output port and a base electrode of the transistor, one end of the second resistor being electrically connected to a midpoint between the first resistor and the base electrode of the transistor, and the other end of the second resistor being electrically connected to a collector electrode of the transistor, the open circuit detection circuit further includes a third resistor connected between the switch circuit and the first connection port, the node being electrically connected to a power supply end so as to provide access to a voltage, and the open circuit detection circuit further includes a fourth resistor, the fourth resistor being electrically connected between the power supply end and the node.

[0020] According to a third aspect of the present invention, there is provided a method for detecting an open circuit in a speaker of a car audio system, the car audio system being the above-mentioned car audio system, the method for detecting an open circuit in the speaker including an open circuit detection step, the open circuit detection step specifically comprising: enabling the output port of the control module to cause the switch circuit to be conductive; If the signal at the input port of the control module is a high level signal, determining that the car speaker is in an open circuit state; determining that the car speaker is in a non-open circuit state if the signal at the input port of the control module is a low level signal.

[0021] In one embodiment, the speaker open circuit detection method further includes enabling the power amplifier to be in a closed state and the output port and the input port to be in a low level state when initially powered on. Effect of the Invention

[0022] The present invention employs the above-mentioned means and has the following advantages over the prior art. In the car audio system and the speaker open circuit detection method of the present invention, an open circuit detection circuit is installed outside the control module, and the signal output from the open circuit detection circuit to the control module input port via the control module can be determined to be high level or low level, thereby determining whether the speaker is open circuited or not, and then disabling the power amplifier or enabling the power amplifier to output normally, which eliminates the need to use an expensive power amplifier chip with open circuit detection function, and can realize speaker open circuit detection at a lower cost. [Brief description of the drawings]

[0023] In order to more clearly describe the technical solutions of the present invention, the following will briefly describe the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are only several embodiments of the present invention, and those skilled in the art can further obtain other drawings based on these drawings without creative efforts.

[0024] [Figure 1] FIG. 1 is a structural block diagram of a car audio system according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a circuit diagram of an open circuit detection circuit according to one embodiment of the present invention. [Diagram 3] 4 is a flowchart of a speaker open circuit detection method according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, the advantages and features of the present invention will be easily understood by those skilled in the art by describing preferred embodiments of the present invention in detail with reference to the accompanying drawings. Hereinafter, it should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features included in the various embodiments of the present invention described below can be combined with each other as long as they are not mutually inconsistent.

[0026] As used in the specification and claims, the terms "comprises" and "including" only mean that the specifically identified steps and elements are inclusive, and that these steps and elements do not constitute an exclusive list; the method or apparatus may include other steps or elements. As used herein, the term "and / or" includes any combination of the associated exemplified items. Furthermore, Although the terms "first", "second", etc. are used to describe various types of information, it can be understood that these information should not be limited to these terms. These terms do not imply any particular order or importance, but are used only to distinguish the same types of information from one another. In fact, the terms "first", "second", etc. can be used completely interchangeably. For example, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information, without departing from the scope of this disclosure.

[0027] As shown in FIG. 1, this embodiment provides a car audio system, including a power amplifier 1 for driving a speaker 2 electrically connected thereto to perform electro-acoustic conversion, and a control module 4 having an output port OpenChk_1 and an input port 1_Open_Sense for controlling the power amplifier 1, the car audio system further includes an open circuit detection circuit 3, a first connection port SPK1- and a second connection port SPK1+ thereof, the first connection port SPK1- is electrically connected to one set (e.g., negative lead) of two sets of leads of the speaker 2, and the second connection port SPK1+ is electrically connected to another set (e.g., positive lead) of two sets of leads of the speaker 2. The output port of the power amplifier is also correspondingly electrically connected to the two sets of leads of the speaker, thereby outputting a digital audio signal or an analog audio signal to the speaker. For a normal speaker, each set of leads includes one lead, that is, the speaker 2 has a pair of leads, and for a multi-sound circle speaker, each set of leads may include multiple leads, that is, the speaker 2 has multiple pairs of leads. As shown in Fig. 2, the open circuit detection circuit 3 further includes a switch circuit 30, which is connected between the output port OpenChk_1 of the control module 4 and the first connection port SPK1- of the open circuit detection circuit 3, and is controlled by a control signal from the output port OpenChk_1 to make the output port OpenChk_1 and the first connection port SPK1- conductive or disconnected. When the entire system is in the initial state of the power amplifier startup, the open circuit detection circuit 3 is enabled through a pulse signal from the output port OpenChk_1 of the control module 4, and then judges through the input port 1_Open_Sense whether the speaker 2 is accessible between the second connection port SPK1+ and the first connection port SPK1- or whether the speaker 2 has an open circuit fault. The power amplifier 1 is specifically a multi-channel power amplifier having multiple channels, and each channel can drive at least one speaker.

[0028] The power amplifier 1 is a BTL power amplifier and a CLASS-D digital power amplifier, which has a short circuit protection function and does not have an open circuit detection function. The control module 4 is a power amplifier chip, specifically a one-chip microcomputer (MCU), which includes a one-chip microcomputer body, an output port OpenChk_1 and an input port 1_Open_Sense, where the output port OpenChk_1 and the input port 1_Open_Sense are IO ports of the power amplifier chip, and the speaker 2 is a speaker with an impedance range of 2 to 8 Ω.

[0029] 2, the switch circuit 30 specifically includes a transistor Q5 (specifically an NPN transistor), the base electrode of the transistor Q5 is electrically connected to the output port OpenChk_1, the collector electrode of the transistor Q5 is electrically connected to the first connection port SPK1-, and the emitter of the transistor Q5 is grounded (has the same potential as the earth). The input port 1_Open_Sense and the second connection port SPK1+ of the control module 4 are respectively connected to the node A, which is electrically connected to the power supply terminal VDD-MCU and accesses the voltage, which is consistent with the working voltage of the power amplifier chip.

[0030] The control module 4 is used to enable the open circuit detection circuit 3 via the output port OpenChk_1 so as to determine whether the speaker is open circuited according to the signal received from the input port 1_Open_Sense.

[0031] The switch circuit 30 further includes a first resistor R65 and a second resistor R73, the first resistor R65 is electrically connected between the output port OpenChk_1 and the base electrode of the transistor Q5, one end of the second resistor R73 is electrically connected to the midpoint between the first resistor R65 and the base electrode of the transistor Q5, and the other end of the second resistor R73 is electrically connected to the collector electrode of the transistor Q5. The first resistor R65, the second resistor R73, and the transistor Q5 together constitute the switch circuit 30.

[0032] The open circuit detection circuit 3 further includes a third resistor R33 connected between the switch circuit and the first connection port SPK1-, and the third resistor R33 is used for current limiting.

[0033] The open circuit detection circuit 3 further includes a fourth resistor R71 having a level for pulling up and transmitting to the IO port, the fourth resistor R71 being electrically connected between the power supply terminal VDD-MCU and the node A.

[0034] The open circuit detection circuit 3 further includes a diode D6 for preventing the power amplifier voltage from reacting to the control module 4, and the diode D6 is electrically connected between the second connection port SPK1+ and the input port 1_Open_Sense. Specifically, the positive electrode of the diode D6 is connected to the node A, and the negative electrode is connected to the second connection port SPK1+.

[0035] The open circuit detection circuit 3 further includes a capacitor C20 for filtering high-frequency signals from the power amplifier, one end of the capacitor C20 being electrically connected to the midpoint between the second connection port SPK1+ and the input port 1_Open_Sense, and the other end being grounded (equal potential to the earth).

[0036] This embodiment further provides a method for detecting an open circuit in a speaker of a car audio system, and the car audio system is the above-mentioned car audio system. As shown in Figure 3, the method for detecting an open circuit in a speaker includes an open circuit detection step, and the open circuit detection step specifically includes: When initially powering, power amplifier 1 is closed and output port OpenChk_1 and input port 1_Open_Sense are enabled to be in a low level state; Enabling the output port OpenChk_1 of the control module 4 to make the switch circuit conductive; determining that speaker 2 is open circuited if the signal at input port 1_Open_Sense of control module 4 is a high level signal; determining that the speaker 2 is in a non-open circuit state if the signal at the input port 1_Open_Sense of the control module 4 is a low level signal.

[0037] In this embodiment, in the initial power-supply stage of the power amplifier system, the MCU does not start the power amplifier chip first, but puts the power amplifier into STANDBY state, at which time the power amplifier output is in high impedance state. The open circuit detection circuit is composed of two IO ports OpenChk_1 and 1_Open_Sense of the MCU, resistors R33, R65, R71, R73, R71, capacitor C20, diode D6, and transistor Q5. Using two IO ports of the MCU, one is set as output and the other is set as input. When power is initially supplied, if the power amplifier output is in high impedance, the output IO port OpenChk_1 of the MCU is enabled to a high level, and thus the transistor Q5 is conductive. When the speaker is inaccessible or there is a fault in the speaker open circuit, 1_Open_Sense is high level, the MCU judges the speaker open circuit, the transistor Q5 is conductive, and when there is a speaker between SPK1+ and SPK1-, the 1_Open_Sense port is pulled down, and when the MCU receives a low level signal on the 1_Open_Sense port, it judges the speaker is in a non-open circuit state. After judging the speaker non-open circuit state, it enables the OpenChk_1 port as a low level output, turns off the transistor Q5, enables the power amplifier output, and puts the power amplifier into a normal working state.

[0038] The car audio system provided in this embodiment has a power amplifier 1, a control module 4 and an open circuit detection circuit 3 that are independent of each other, and can determine whether the speaker is open circuited by determining whether the signal at the input terminal 1_Open_Sense of the control module 4 is at a high level or a low level, and thereby disable the power amplifier or enable the power amplifier to output normally.

[0039] The speaker open circuit detection method provided by this embodiment can complete the open circuit detection for the speaker without assuming an external circuit and system, and does not require the use of an expensive power amplifier chip with open circuit detection function, while at the same time not affecting the normal operation of the system, and can realize the open circuit detection for the speaker at a lower cost.

[0040] The above embodiments are only intended to illustrate the technical concepts and features of the present invention, and are preferred embodiments, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, which cannot limit the protection scope of the present invention.

Claims

1. a power amplifier for driving an electrically connected car speaker; a control module having an output port and an input port for controlling the power amplifier, The car audio system further comprises: an open circuit detection circuit, the open circuit detection circuit having a first connection port and a second connection port, the second connection port being electrically connected to a positive lead of the car speaker, and the first connection port being electrically connected to a negative lead of the car speaker; the open circuit detection circuit includes a switch circuit, the switch circuit being connected between an output port of the control module and the first connection port, the switch circuit including a transistor, a base electrode of the transistor being electrically connected to the output port, a collector electrode of the transistor being electrically connected to the first connection port, and an emitter electrode of the transistor being grounded, and being controlled by a control signal from the output port to connect or disconnect the emitter electrode and the first connection port; The input port of the control module and the second connection port are each electrically connected to a node, the node being used to access a voltage, and the node being electrically connected to a power supply end so as to access the voltage; the control module is used to enable the open circuit detection circuit via the output port and determine whether a speaker is in an open circuit state in response to a signal received from the input port; The open circuit detection circuit further includes a diode for preventing a power amplifier voltage from being fed back to the control module, the diode being electrically connected between the second connection port and the node; The control module is configured to determine that the car speaker is in a non-open circuit state after receiving a low-level signal from the input port, and enable the output port to output a low-level signal, thereby turning off the transistor and enabling the output of the power amplifier.

2. 2. The car audio system of claim 1, wherein the switch circuit further includes a first resistor and a second resistor, the first resistor being electrically connected between the output port and a base electrode of the transistor, one end of the second resistor being electrically connected to a midpoint between the first resistor and the base electrode of the transistor, and the other end of the second resistor being grounded.

3. 2. The car audio system according to claim 1, wherein the open circuit detection circuit further comprises a third resistor connected between the collector electrode of the transistor and the first connection port.

4. 2. The car audio system according to claim 1, wherein the open circuit detection circuit further includes a fourth resistor, the fourth resistor being electrically connected between the power supply end and the node.

5. 2. The car audio system according to claim 1, wherein the open circuit detection circuit further includes a capacitor, one end of the capacitor being electrically connected to a midpoint between the second connection port and the input port, and the other end of the capacitor being grounded.

6. The car audio system according to any one of claims 1 to 5, characterized in that the power amplifier is a BTL power amplifier and / or the control module is a power amplifier chip, and the output port and the input port are IO ports of the power amplifier chip, respectively.

7. 2. The car audio system according to claim 1, wherein the car speaker has an impedance range of 2 to 8 Ω.

8. 8. A method for detecting an open circuit in a speaker of a car audio system, the car audio system being the car audio system according to claim 1, the method for detecting an open circuit in the speaker including a step of detecting an open circuit, the step of detecting an open circuit comprising: enabling the output port of the control module high to make the transistor conductive; If the signal at the input port of the control module is a high level signal, determining that the car speaker is in an open circuit state; and determining that the car speaker is in a non-open circuit state when the signal at the input port of the control module is a low level signal.

9. The speaker open circuit detection method further includes the steps of: enabling the power amplifier to be in a closed state and the output port and the input port to be in a low level state when initially powering on; 9. The method for detecting an open circuit in a speaker as described in claim 8, further comprising the steps of: enabling the output port to output a low level signal to turn off the transistor and enable the output of the power amplifier after determining that the car speaker is in a non-open circuit state.

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