JP6349791B2 - Short-circuit determination device and short-circuit detection method - Google Patents

Description

  The present invention relates to a short circuit determination device and a short circuit detection method for determining whether or not an output terminal of an amplifier circuit is in a short circuit state.

  Patent Document 1 discloses an example of a protection circuit that prevents destruction of the amplifier circuit when the output terminal of the amplifier circuit is in a short circuit state. Specifically, Japanese Patent Laid-Open No. 2004-228867 prevents the amplifier circuit from being destroyed when a shift in the midpoint potential between the positive power supply voltage and the negative power supply voltage of the amplifier circuit (digital amplifier) is detected. A protection circuit that performs a protection operation is disclosed.

JP 2006-60278 A

  In Patent Document 1, what kind of current (in other words, a signal) is specifically input to the input terminal of the amplifier circuit while detecting a shift in the midpoint potential between the positive power supply voltage and the negative power supply voltage. There is no disclosure of what is being done. For this reason, even when the protection operation is performed by detecting a shift in the midpoint potential between the positive power supply voltage and the negative power supply voltage, the amplifier circuit may be destroyed depending on the current input to the amplifier circuit. This causes a technical problem that may be caused.

  For example, a sound signal indicating some sound is normally input to the input terminal of the amplifier circuit. Here, in Patent Document 1, the sound signal normally input to the input terminal of the amplifier circuit performs a protection operation by detecting a shift in the midpoint potential between the positive power supply voltage and the negative power supply voltage. It is not a special signal prepared for. That is, in Patent Document 1, when detecting a shift in the midpoint potential between the positive power supply voltage and the negative power supply voltage, a shift in the midpoint potential between the positive power supply voltage and the negative power supply voltage is detected. Regardless of whether or not is detected, an audio signal that is normally input is passively input to the input terminal of the amplifier circuit. In other words, in Patent Document 1, when detecting a shift in the midpoint potential between the positive power supply voltage and the negative power supply voltage, it is used to perform a protection operation by detecting the shift in the midpoint potential. The special signal generated is not actively input to the input terminal of the amplifier circuit. For this reason, in Patent Document 1, depending on the input audio signal, even if the protection operation is performed by detecting a shift in the midpoint potential between the positive power supply voltage and the negative power supply voltage, amplification is performed. Depending on the audio signal input to the circuit, there arises a technical problem that the amplifier circuit may be destroyed.

  Examples of problems to be solved by the present invention include the above. It is an object of the present invention to provide a short-circuit determination device and a short-circuit detection method capable of determining whether or not an output terminal of an amplifier circuit is in a short-circuit state while more suitably preventing destruction of the amplifier circuit. .

In order to solve the above-described problem, a short-circuit determination device according to the present invention includes a generation unit that generates a predetermined inspection signal used to determine whether or not an output terminal of an amplifier circuit is in a short-circuit state, and the generation unit includes: While the generated inspection signal is input to the input terminal of the amplifier circuit, a detection unit that detects a voltage value of a power supply of the amplifier circuit, and the output based on the voltage value detected by the detection unit Determination means for determining whether or not the terminal is in the short-circuit state, the amplifier circuit is a half-bridge type D amplifier, and the inspection signal is a capacitor attached to the power source of the amplifier circuit. An AC signal having a frequency equal to or lower than a first frequency determined according to a capacity, and the inspection signal has a signal level at the time when it reaches the output terminal, and (i) the inspection signal is input to the input terminal, Above A second signal level capable of causing a pumping phenomenon in the amplifier circuit under a situation where the power terminal is in the short-circuit state; and (ii) the amplification resulting from the input of the test signal to the input terminal The second signal level is capable of suppressing the destruction of the circuit.

In order to solve the above-described problem, a short-circuit determination method of the present invention includes a generation step of generating a predetermined inspection signal used to determine whether or not an output terminal of an amplifier circuit is in a short-circuit state, and the generation step While the generated inspection signal is being input to the input terminal of the amplifier circuit, based on the detection step of detecting the voltage value of the power supply of the amplifier circuit, and the voltage value detected in the detection step, A determination step of determining whether or not the output terminal is in the short circuit state, the amplifier circuit is a half-bridge type D amplifier, and the inspection signal is associated with the power source of the amplifier circuit An AC signal having a frequency equal to or lower than a first frequency determined according to the capacitance of the capacitor, and the inspection signal has a signal level when it reaches the output terminal, and (i) the inspection signal is input to the input terminal. And a second signal level capable of causing a pumping phenomenon in the amplifier circuit in a state where the output terminal is in the short-circuit state, and (ii) input of the inspection signal to the input terminal The second signal level can suppress the destruction of the amplifier circuit due to the above .

  Such an operation and gain of the present invention will be clarified from the embodiments described below.

It is a block diagram which shows an example of a structure of the amplification system of a present Example. It is a flowchart which shows the flow of the operation | movement (namely, short circuit determination operation | movement) which determines whether SP output is in a short circuit state.

  Hereinafter, embodiments of the short-circuit determination device and the short-circuit detection method of the present invention will be described in order as modes for carrying out the invention.

(Embodiment of short-circuit determination device)
<1>
The short circuit determination device of the present embodiment includes a generation unit that generates a predetermined inspection signal used to determine whether or not the output terminal of the amplifier circuit is in a short circuit state, and the inspection signal generated by the generation unit A detection means for detecting a voltage value of a power supply of the amplification circuit while being input to the input terminal of the amplification circuit, and the output terminal is brought into the short-circuit state based on the voltage value detected by the detection means. Determination means for determining whether or not there is.

  According to the short circuit determination device of the present embodiment, the generation unit generates a predetermined inspection signal used for determining whether or not the output terminal of the amplifier circuit is in a short circuit state. That is, in this embodiment, when it is determined whether or not the output terminal of the amplifier circuit is in a short circuit state, the output terminal of the amplifier circuit is in a short circuit state instead of the audio signal normally input to the amplifier circuit. A test signal that is specially used to determine whether or not it exists is generated. In other words, in this embodiment, the generation unit actively generates a special inspection signal when it is determined whether or not the output terminal of the amplifier circuit is in a short circuit state.

  The detection means detects the voltage value of the power supply of the amplifier circuit (typically, the value of the voltage between the terminals). In particular, the detection unit detects the voltage value of the power supply of the amplifier circuit while the inspection signal generated by the generation unit is input to the input terminal of the amplifier circuit.

  The determining means determines whether or not the output terminal is in a short circuit state based on the voltage value detected by the detecting means. For example, the determination unit may determine that the output terminal is in a short circuit state when the voltage value detected by the detection unit is a predetermined value. On the other hand, for example, the determination unit may determine that the output terminal is not in a short-circuit state when the voltage value detected by the detection unit does not become a predetermined value.

  Here, the voltage value of the power supply of the amplifier circuit varies due to a “pumping phenomenon” generated in the amplifier circuit. Such a pumping phenomenon is particularly noticeable when the output terminal of the amplifier circuit is in a short-circuited state. Therefore, the determination unit can determine that the output terminal is in a short-circuited state when the voltage value detected by the detection unit becomes a predetermined value that directly or indirectly indicates the occurrence of the pumping phenomenon. On the other hand, for example, the determination unit may determine that the output terminal is not short-circuited when the voltage value detected by the detection unit does not become a predetermined value that directly or indirectly indicates the occurrence of the pumping phenomenon. it can. As described above, the determination unit can preferably determine whether or not the output terminal of the amplifier circuit is in a short circuit state by monitoring the voltage value of the power supply of the amplifier circuit.

  Particularly in this embodiment, when it is determined whether or not the output terminal of the amplifier circuit is in a short circuit state, the input terminal of the amplifier circuit detects whether or not the output terminal of the amplifier circuit is in a short circuit state. A special test signal used to do this is actively input. For this reason, in the present embodiment, an audio signal normally input to the amplifier circuit (that is, an audio signal that may cause destruction of the amplifier circuit depending on its characteristics) is passively input to the input terminal of the amplifier circuit. In comparison, destruction (for example, electrical destruction) of the amplifier circuit is preferably prevented.

  As described above, the short-circuit determination device according to the present embodiment can determine whether or not the output terminal of the amplifier circuit is in a short-circuit state while more suitably preventing the amplifier circuit from being destroyed.

<2>
In another aspect of the short circuit determination device of the present embodiment, the inspection signal is at least one of an AC signal having a frequency equal to or lower than a first frequency determined according to a capacity of a capacitor attached to the power supply of the amplifier circuit, and a DC signal. Including one.

  According to this aspect, when an AC signal having a frequency equal to or lower than the first frequency is input to the input terminal, a signal different from the AC signal having the frequency equal to or lower than the first frequency (excluding the DC signal) is input to the input terminal. Compared to the case, the pumping phenomenon is relatively likely to occur in a situation where the output terminal is in a short-circuited state. For this reason, the short circuit determination device monitors the voltage value of the power supply of the amplifier circuit while such an inspection signal is input to the input terminal, so that the output terminal It can be determined suitably whether it is in a short circuit state.

  As described above, in this embodiment, whether or not the output terminal is in a short-circuited state depends on whether or not a pumping phenomenon occurs in the amplifier circuit while the inspection signal is input to the input terminal. Determined. In consideration of this, the AC signal having the first frequency or lower is an AC signal that can cause the amplifier circuit to generate a pumping phenomenon by being input to the input terminal under a situation where the output terminal is short-circuited. It is preferable. Here, as a result of research by the inventors of the present application, the frequency of the AC signal that can generate a pumping phenomenon in the amplifier circuit when the output terminal is input to the input terminal in a short-circuited state is It has been found that it can vary depending on the capacitance of the capacitor associated with the power supply. For this reason, an AC signal having a frequency equal to or lower than the first frequency determined according to the capacity of the capacitor associated with the power supply of the amplifier circuit is input to the input terminal, and thus is determined without considering the capacity of the capacitor associated with the power supply of the amplifier circuit. Compared with a case where an AC signal having another frequency is input to the input terminal, a pumping phenomenon is relatively likely to occur in the amplifier circuit under a situation where the output terminal is in a short-circuited state. Therefore, the short circuit determination device monitors the voltage value of the power source of the amplifier circuit while an AC signal having a frequency equal to or lower than the first frequency determined according to the capacitance of the capacitor attached to the power source of the amplifier circuit is input to the input terminal. Thus, it is possible to preferably determine whether or not the output terminal is in a short-circuited state while preventing the amplifier circuit from being destroyed more suitably.

<3>
In another aspect of the short-circuit determination device of the present embodiment, the inspection signal causes a pumping phenomenon to occur in the amplifier circuit when the inspection signal is input to the input terminal in a state where the output terminal is in the short-circuit state. It includes at least one of a second frequency AC signal and a DC signal that can be generated.

  According to this aspect, when an AC signal having the second frequency is input to the input terminal, a signal different from the AC signal having the second frequency or less (excluding the DC signal) is input to the input terminal. In comparison with the above, the pumping phenomenon is relatively likely to occur in a situation where the output terminal is in a short-circuited state. For this reason, the short circuit determination device monitors the voltage value of the power supply of the amplifier circuit while such an inspection signal is input to the input terminal, so that the output terminal It can be determined suitably whether it is in a short circuit state.

  The second frequency is typically a frequency equal to or lower than the first frequency described above.

<4>
In another aspect of the short circuit determination device of the present embodiment, the inspection signal includes a DC signal.

  According to this aspect, when a DC signal is input to the input terminal, a pumping phenomenon occurs in a situation where the output terminal is in a short-circuited state, compared to a case where a signal different from the DC signal is input to the input terminal. Is relatively likely to occur. For this reason, the short circuit determination device monitors the voltage value of the power supply of the amplifier circuit while such an inspection signal is input to the input terminal, so that the output terminal It can be determined suitably whether it is in a short circuit state.

<5>
In another aspect of the short circuit determination device of the present embodiment, the inspection signal is a first signal whose signal level at the time when it reaches the output terminal is determined according to the capacitance of the capacitor associated with the power supply of the amplifier circuit. It includes at least one of an AC signal and a DC signal that are lower than the level.

  According to this aspect, when an AC signal whose signal level when reaching the output terminal is equal to or lower than the first signal level is input to the input terminal, the signal level when reaching the output terminal is the first level. Compared with the case where an AC signal greater than the signal level is input to the input terminal, the pumping phenomenon is relatively likely to occur in a situation where the output terminal is in a short-circuited state, and the destruction of the amplifier circuit is preferably prevented. . Alternatively, when a DC signal whose signal level when reaching the output terminal is equal to or lower than the first signal level is input to the input terminal, the signal level when reaching the output terminal is higher than the first signal level. Compared with the case where a DC signal is input to the input terminal, the pumping phenomenon is relatively likely to occur under a situation where the output terminal is in a short-circuited state, and destruction of the amplifier circuit is preferably prevented. For this reason, the short circuit determination device monitors the voltage value of the power supply of the amplifier circuit while such an inspection signal is input to the input terminal, so that the output terminal It can be determined suitably whether it is in a short circuit state.

  As described above, in the present embodiment, it is determined whether or not the output terminal is in a short-circuited state depending on whether or not a pumping phenomenon occurs in the amplifier circuit when the inspection signal is input to the input terminal. Is done. In consideration of this, a signal whose signal level when reaching the output terminal is equal to or lower than the first signal level (that is, an AC signal or a DC signal) is input to the input terminal under a situation where the output terminal is in a short-circuited state. It is preferable that the input signal is a signal that can cause a pumping phenomenon in the amplifier circuit. Here, as a result of research by the inventors of the present application, the signal level of a signal that can cause a pumping phenomenon in the amplifier circuit when the output terminal is input to the input terminal in a short-circuited state is It has been found that it can vary depending on the capacitance of the capacitor associated with the power supply. For this reason, when the signal level when reaching the output terminal is equal to or lower than the first signal level determined according to the capacitance of the capacitor attached to the power supply of the amplifier circuit, the signal reaches the output terminal. The output terminal is in a short-circuited state compared to the case where a signal with a different signal level is determined without considering the capacitance of the capacitor attached to the power supply of the amplifier circuit. Below, a pumping phenomenon is relatively likely to occur in the amplifier circuit. Therefore, the short-circuit determination device is configured so that the signal level at the time of reaching the output terminal is inputted to the input terminal while the signal whose level is equal to or lower than the first signal level determined according to the capacitance of the capacitor attached to the power supply of the amplifier circuit. By monitoring the voltage value of the power supply of the amplifier circuit, it is possible to preferably determine whether or not the output terminal is in a short-circuited state while more suitably preventing the amplifier circuit from being destroyed.

<6>
In another aspect of the short-circuit determination device of the present embodiment, the inspection signal has a signal level at the time when the inspection signal reaches the output terminal, and (i) the inspection signal is input to the input terminal, so that the output A second signal level capable of causing the amplifier circuit to generate a pumping phenomenon under a situation where the terminal is in the short-circuit state; and (ii) the amplifier circuit resulting from the input of the inspection signal to the input terminal Including at least one of an AC signal and a DC signal at a second signal level capable of suppressing the destruction of the signal.

  According to this aspect, when a signal (that is, an AC signal or a DC signal) at which the signal level when reaching the output terminal becomes the second signal level is input to the input terminal, the time when the signal reaches the output terminal Compared with the case where a signal having a signal level different from that of the second signal level is input to the input terminal, the pumping phenomenon is relatively likely to occur in a situation where the output terminal is short-circuited. For this reason, the short circuit determination device monitors the voltage value of the power supply of the amplifier circuit while such an inspection signal is input to the input terminal, so that the output terminal It can be determined suitably whether it is in a short circuit state.

  Note that the second signal level is typically a signal level equal to or lower than the first signal level described above.

<7>
In another aspect of the short circuit determination device of the present embodiment, the amplifier circuit is a half-bridge class D amplifier.

  According to this aspect, the determination means can preferably determine whether or not the output terminal is in a short-circuited state using a pumping phenomenon that is likely to occur in a half-bridge type D amplifier.

(Embodiment of short circuit detection method)
<8>
The short-circuit detection method of the present embodiment includes a generation step of generating a predetermined inspection signal used for determining whether or not the output terminal of the amplifier circuit is in a short-circuit state, and the inspection signal generated in the generation step Detecting the voltage value of the power supply of the amplifier circuit while the input terminal of the amplifier circuit is being input, and based on the voltage value detected in the detection step, the output terminal is short-circuited And a determination step of determining whether or not it is in a state.

  According to the short circuit detection method of the present embodiment, it is possible to receive the same benefits as the various benefits of the short circuit determination device of the present embodiment described above. Incidentally, in response to various aspects of the short-circuit determination device of the present embodiment described above, the short-circuit detection method of the present embodiment can also adopt various aspects.

  Such an operation and other advantages of the present embodiment will be further clarified from examples described below.

  As described above, the short circuit determination device of this embodiment includes a generation unit, a detection unit, and a determination unit. The short circuit detection method of this embodiment includes a generation step, a detection step, and a determination step. Therefore, it is possible to determine whether or not the output terminal of the amplifier circuit is in a short-circuited state while more suitably preventing the amplifier circuit from being destroyed.

  Hereinafter, embodiments of the short-circuit determination device and the short-circuit detection method of the present invention will be described with reference to the drawings.

(1) Configuration of the amplification system First, the configuration of the amplification system 100 of the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating an example of the configuration of the amplification system 100 of the present embodiment.

  As illustrated in FIG. 1, the amplification system 100 includes an amplifier unit 1 that is a specific example of an “amplifier circuit” and a short circuit detection unit 3 that is a specific example of a “short circuit determination device”.

  The amplifier unit 1 is a half-bridge class D amplifier. However, the amplifier unit 1 may be an amplifier different from a half-bridge class D amplifier.

  The amplifier unit 1 includes an SG input 11, which is a specific example of “input terminal”, a preamplifier 12, a comparator 13, a power amplifier 14, a relay 15, and a first power supply 16a which is a specific example of “power supply”. A second power supply 16b that is a specific example of “power supply”, a first capacitor 17a that is a specific example of “capacitor”, a second capacitor 17b that is a specific example of “capacitor”, and an “output terminal” And SP output 18 as a specific example.

  The SG input 11 is an input terminal to which an audio signal to be amplified by the amplifier unit 1 is input. In the present embodiment, in particular, the SG input 11 receives an inspection signal generated by a short-circuit determination device 3 described later in addition to or instead of the audio signal. When the amplifier unit 1 includes a plurality of channels, the amplifier unit 1 may include a plurality of SG inputs 11 respectively corresponding to the plurality of channels.

  The preamplifier 12 adjusts the signal level of the signal (that is, the audio signal or the inspection signal) input to the SG input 11.

  The comparator 13 compares the signal level of the signal (that is, the audio signal or the inspection signal) input to the SG input 11 with the signal level of a predetermined carrier signal (for example, a triangular wave signal), thereby switching the switch control signal (for example, , PWM (Pulse Width Modulation) signal). The switch control signal is a control signal for controlling the operating state of the power amplifier 14 (particularly, the first switching element 14b and the second switching element 14c). The comparator 13 outputs the generated switch control signal to the power amplifier 14.

  The power amplifier 14 adjusts (typically amplifies) the signal level of the signal (that is, the audio signal or the inspection signal) input to the SG input 11. Such a power amplifier 14 includes an inverter 14a, a first switching element 14b, a second switching element 14c, and an LPF (Low Pass Filter) 14d.

  The inverter 14 a inverts the signal level of the switch control signal output from the comparator 13. The inverter 14a outputs the signal level of the switch control signal obtained by inverting the signal level to the second switching element 14c.

  The first switching element 14 b switches the switching state based on the switch control signal output from the comparator 13. The second switching element 14 c switches the switching state based on the switch control signal output from the inverter 14. That is, the first switching element 14b and the second switching element 14c switch the switching state complementarily. As a result, the signal level of the signal input to the SG input 11 (that is, the audio signal or the inspection signal) is amplified.

  The LPF 14d is a filter that removes high-frequency noise from a signal whose signal level is amplified by switching the switching state of the first switching element 14b and the second switching element 14c. The LPF 14d includes a coil 141d and a capacitor 142d. The LPF 14 d outputs a signal from which high frequency noise has been removed to the relay 15.

  The power amplifier 14 may have the function of the preamplifier 12. In this case, the amplifier unit 1 may not include the preamplifier 12.

  The relay 15 is an element for switching an electrical connection state between the power amplifier 14 and the SP output 18. When the relay 15 is in the closed state, the electrical connection state between the power amplifier 14 and the SP output 18 is a conduction state. Therefore, the signal output from the power amplifier 14 is output via the SP output 18 to the external load (for example, speaker) SP connected to the SP output 18. On the other hand, when the relay 15 is in the open state, the electrical connection state between the power amplifier 14 and the SP output 18 is a non-conduction state. Therefore, the signal output from the power amplifier 14 does not reach the SP output 18.

  The SP output 18 is an output terminal for outputting a signal (typically an audio signal) amplified by the amplifier unit 1. In this embodiment, it is assumed that an external load (for example, a speaker) SP is connected to the SP output 18. When the amplifier unit 1 includes a plurality of channels, the amplifier unit 1 may include a plurality of SP outputs 18 respectively corresponding to the plurality of channels.

  Subsequently, the short circuit determination device 3 includes an inspection signal generator 31 that is a specific example of “generating means”, a first voltage detector 32a that is a specific example of “detecting means”, and one of “detecting means”. A second voltage detector 32b, which is a specific example, a controller 33, and a relay drive circuit 34 are provided.

  The inspection signal generator 31 generates an inspection signal under the control of a signal control unit 331 provided in the controller 33 described later. Here, the inspection signal is a special signal (for example, an audio signal or an electric signal) used for determining whether or not the SP output 18 is in a short-circuit state. The inspection signal generated by the inspection signal generator 31 is input to the SG input 11.

  The first voltage detector 32a detects the inter-terminal voltage V1 of the first power supply 16a. The second voltage detector 32b detects the inter-terminal voltage V2 of the second power supply 16b.

  The controller 33 is a control unit that controls the operation of the entire short-circuit determination device 3. In this embodiment, the controller 33 includes a signal control unit 331 as a processing block that is logically realized in the controller 33 by a computer program being executed by the controller 33 or a physical processing circuit in the controller 33. A short-circuit determination unit 332, which is a specific example of “determination unit”, is provided.

  The signal control unit 331 controls the inspection signal generator 31 so that the inspection signal generator 31 generates a desired inspection signal. The inspection signal generated under the control of the signal control unit 331 will be described in detail later.

  The short-circuit determination unit 332 determines the SP based on the detection result of at least one of the first voltage detector 32a and the second voltage detector 32b (that is, at least one of the inter-terminal voltage V1 and the inter-terminal voltage V2). It is determined whether the output 18 is in a short circuit state. Specifically, when the SP output 18 is in a short circuit state, a pumping phenomenon is likely to occur in the amplifier unit 1. When the pumping phenomenon occurs, at least one of the inter-terminal voltage V1 and the inter-terminal voltage V2 varies greatly as compared with the case where the pumping phenomenon does not occur. Therefore, when at least one of the inter-terminal voltage V1 and the inter-terminal voltage V2 shows an abnormal value, a pumping phenomenon has occurred, and as a result, it is estimated that the SP output 20 is in a short-circuit state. . Thus, the short circuit determination unit 332 can determine whether the SP output 18 is in a short circuit state based on at least one of the inter-terminal voltage V1 and the inter-terminal voltage V2.

  Particularly in the present embodiment, the short-circuit determination unit 332 performs SP based on the detection result of at least one of the first voltage detector 32a and the second voltage detector 32b while the inspection signal is input to the SG input 11. It is determined whether the output 18 is in a short circuit state.

  The relay drive circuit 34 controls the relay 15 based on the determination result of the short circuit determination unit 332. Specifically, when the SP output 18 is determined to be in a short circuit state by the short circuit determination unit 332, the relay drive circuit 34 controls the relay 15 so that the relay 15 is in an open state. On the other hand, the relay drive circuit 34 controls the relay 15 so that the relay 15 is closed when the short circuit determination unit 332 determines that the SP output 18 is not in the short circuit state.

  The short circuit determination device 3 described above can determine whether or not the SP output 18 is in a short circuit state. Hereinafter, the flow of an operation for determining whether or not the SP output 18 is in a short circuit state (hereinafter, referred to as “short circuit detection operation” as appropriate) will be further described.

(2) Flow of Short-Circuit Determination Operation Next, the flow of the operation for determining whether or not the SP output 18 is in a short-circuit state (that is, the short-circuit determination operation) will be described with reference to FIG. FIG. 2 is a flowchart showing a flow of an operation for determining whether or not the SP output 18 is in a short circuit state (that is, a short circuit determination operation).

  The short-circuit detection operation described below is preferably performed before a normal audio signal is input to the amplifier unit 1. For example, the short circuit detection operation is preferably performed as a part of the initial operation when the amplifier unit 1 starts the operation.

  As shown in FIG. 2, the controller 33 appropriately sets the operation parameter of the amplifier unit 1 so that the inspection signal input to the SG input 11 can reach the SP output 18 (step S11). For example, the controller 33 may appropriately set operation parameters that define the band of the signal path in the amplifier unit 1 so that the inspection signal can reach the SP output 18.

  Note that the controller 33 preferably sets operation parameters based on characteristics (for example, frequency, signal level, etc.) of the inspection signal generated by the inspection signal generator 31. For example, the controller 33 appropriately sets the operation parameter of the amplifier unit 1 based on the frequency of the test signal generated by the test signal generator 31 so that the test signal of the frequency can reach the SP output 18. May be.

  Subsequent to or in parallel with the operation of step S11, the controller 33 sets the signal level of the inspection signal when the inspection signal input to the SG input 11 reaches the SP output 18 (hereinafter referred to as appropriate). The amplification factor of the preamplifier 12 (and further the power amplifier 14 if necessary) is adjusted as appropriate so that “referred to as“ output signal level ”” becomes a prescribed signal level (step S12). For example, the controller 33 may increase the amplification factor of the preamplifier 12 so that the output signal level of the inspection signal becomes a signal level that is high enough to cause a pumping phenomenon in the amplifier unit 1 in which the SP output 18 is in a short circuit state. May be adjusted as appropriate. Furthermore, for example, the controller 33 is configured so that the output signal level of the inspection signal is a signal level that is small enough to prevent the destruction of various elements included in the amplifier unit 1 (in other words, not to destroy). The amplification factor of the preamplifier 12 may be adjusted as appropriate. In the present embodiment, for example, the controller 33 causes the preamplifier 12 so that the output signal level of the inspection signal is about 1 Vp-p (that is, the difference between the peak value and the bottom value of the output signal level is about 1 V). The amplification factor may be adjusted as appropriate.

  The controller 33 preferably adjusts the amplification factor of the preamplifier 12 based on the characteristics (for example, frequency, signal level, etc.) of the test signal generated by the test signal generator 31. For example, the controller 33 may appropriately adjust the amplification factor of the preamplifier 12 based on the signal level of the test signal generated by the test signal generator 31 so that the output signal level of the test signal becomes a specified signal level. Good.

  Thereafter, the signal control unit 331 controls the inspection signal generator 31 to generate an inspection signal (step S13). At this time, it is preferable that the signal control unit 331 controls the inspection signal generator 31 so as to generate an AC signal having a predetermined frequency or less as the inspection signal.

  The reason why an AC signal having a predetermined frequency or less is generated as the inspection signal is as follows. First, in this embodiment, as described above, whether or not the pumping phenomenon occurs in the amplifier unit 1 (that is, whether or not at least one of the inter-terminal voltage V1 and the inter-terminal voltage V2 shows an abnormal value). ) To determine whether or not the SP output 18 is in a short circuit state. Here, as the frequency of the inspection signal input to the SG input 11 is smaller, the pumping phenomenon is more likely to occur in the amplifier unit 1 in which the SP output 18 is in a short circuit state. For this reason, in order to make it easy to determine whether or not the SP output 18 is in a short-circuit state, it is only necessary that the pumping phenomenon easily occurs in the amplifier unit 1. In order to easily cause a pumping phenomenon in the amplifier unit 1, it is preferable that an AC signal having a frequency as small as possible is generated as a test signal. For this reason, in this embodiment, an AC signal having a predetermined frequency or less is generated as an inspection signal.

  Considering the reason for generating such an AC signal with a predetermined frequency or less, the signal control unit 331 generates a pumping phenomenon in the amplifier unit 1 in which the SP output 18 is short-circuited by being input to the SG input 11. The test signal generator 31 may be controlled so as to generate an AC signal having a frequency as large as possible as a test signal. In the present embodiment, for example, the signal control unit 331 may control the inspection signal generator 31 so as to generate an AC signal having a frequency of 2 Hz or less (or 1 Hz to 2 Hz) as the inspection signal.

  Here, the frequency of the AC signal that can cause a pumping phenomenon to occur in the amplifier unit 1 in which the SP output 18 is short-circuited by being input to the SG input 11 is the first capacitor 17a associated with the first power supply 16a. And may vary according to the capacity of at least one of the second capacitors 17b associated with the second power supply 16b. Accordingly, the signal control unit 331 generates a test signal generator having a frequency determined according to the capacitance of at least one of the first capacitor 17a and the second capacitor 17b (or lower than the frequency). 31 is preferably controlled. However, the signal control unit 331 does not consider the capacitance of at least one of the first capacitor 17a and the second capacitor 17b, and has a frequency that is predetermined as a frequency that satisfies the above-described condition (or the frequency) The inspection signal generator 31 may be controlled to generate an inspection signal (below).

  The signal control unit 331 takes into consideration the amplification factor of the preamplifier 12 set in step S12, and the signal level of the inspection signal generated by the inspection signal generator 31 (in other words, input to the SG input 11) ( Hereinafter, the inspection signal generator 31 may be controlled so that the “input signal level” is appropriately set to a desired signal level. For example, the signal control unit 331 generates an inspection signal having an input signal level that allows the output signal level of the inspection signal to be a specified signal level in consideration of the amplification factor of the preamplifier 12 set in step S12. As described above, the inspection signal generator 31 may be controlled. Specifically, for example, the signal control unit 331 pumps the output signal level of the inspection signal to the amplifier unit 1 in which the SP output 18 is short-circuited in consideration of the amplification factor of the preamplifier 12 set in step S12. The test signal generator 31 may be controlled so as to generate a test signal having an input signal level that can be set to a signal level that is high enough to cause a phenomenon. Alternatively, for example, the signal control unit 331 can prevent destruction of various elements included in the amplifier unit 1 with the output signal level of the inspection signal in consideration of the amplification factor of the preamplifier 12 set in step S12. The test signal generator 31 may be controlled so as to generate a test signal having an input signal level that can be set to a signal level as small as possible (in other words, not destroyed).

  Thereafter, the test signal generator 31 inputs the test signal generated in step S13 to the SG input 11 of the test target channel of the amplifier unit 1 (step S14).

  While the inspection signal is input to the SG input 11, the short circuit determination unit 332 detects the detection result (that is, the inter-terminal voltages V1 and V2) of at least one of the first voltage detector 32a and the second voltage detector 32b. Of at least one of them. The short circuit determination unit 332 determines whether the SP output 18 is in a short circuit state based on the monitoring result.

  More specifically, the short circuit determination unit 332 determines whether or not the inter-terminal voltage V1 detected while the inspection signal is input to the SG input 11 indicates an abnormal value (step S15). Similarly, the short circuit determination unit 332 determines whether or not the inter-terminal voltage V2 detected while the inspection signal is input to the SG input 11 indicates an abnormal value (step S15). Here, the “abnormal value” corresponds to at least one of the inter-terminal voltages V1 and V2 detected when the pumping phenomenon occurs in the amplifier unit 1. That is, when the pumping phenomenon occurs in the amplifier unit 1, at least one of the inter-terminal voltages V1 and V2 shows an abnormal value. On the other hand, when the pumping phenomenon does not occur in the amplifier unit 1, neither of the inter-terminal voltages V1 and V2 shows an abnormal value.

  As a result of the determination in step S15, when it is determined that at least one of the inter-terminal voltages V1 and V2 indicates an abnormal value (step S15: Yes), the short circuit determination unit 332 determines the SP of the inspection target channel. It is determined that the output 18 is in a short circuit state (step S16). In this case, in order to prevent an overcurrent caused by the SP output 18 being in a short-circuited state from flowing into the amplifier unit 1 via the SP output 18 in a short-circuited state, the relay drive circuit 34 The relay 15 is controlled so as to be in the open state. As a result, the relay 15 is opened (step S17). As a result, an overcurrent caused by the SP output 18 being in a short circuit state is prevented from flowing into the amplifier unit 1.

  On the other hand, as a result of the determination in step S15, when it is determined that both of the inter-terminal voltages V1 and V2 do not indicate abnormal values (step S15: No), the short circuit determination unit 332 determines the SP of the inspection target channel. It determines with the output 18 not being in a short circuit state (step S18). In this case, since it is relatively less necessary to prevent the overcurrent caused by the SP output 18 being in a short circuit state from flowing into the amplifier unit 1, the relay drive circuit 34 causes the relay 15 to be in the closed state. Thus, the relay 15 is controlled. As a result, the relay 15 is closed (step S19). As a result, a signal (typically an audio signal) amplified by the amplifier unit 1 is output to the external load SP.

  Thereafter, the short-circuit determination unit 332 determines whether or not the determination as to whether or not the SP output 18 is in a short-circuit state has been completed for all channels included in the amplifier unit 1 (step S20).

  As a result of the determination in step S20, when it is determined that the determination as to whether or not the SP output 18 is in a short-circuit state has been completed for all channels (step S20: No), the controller 33 A channel for which the determination of whether or not the SP output 18 is in a short-circuited state is not completed is set as a new inspection target channel (step S21). Thereafter, the operations after step S14 are performed for the new inspection target channel. That is, whether the SP output 18 of the inspection target channel is in a short-circuited state based on at least one of the inter-terminal voltages V1 and V2 detected while the inspection signal is input to the SG input 11 of the new inspection target channel. It is determined whether or not.

  On the other hand, as a result of the determination in step S20, when it is determined that the SP output 18 is in a short circuit state for all channels (step S20: Yes), the short circuit is performed. The determination device 3 ends the operation.

  As described above, the short circuit determination device 3 according to the present embodiment has the SP output 18 in the short circuit state based on the determination result of whether or not at least one of the inter-terminal voltages V1 and V2 shows an abnormal value. It can be determined whether or not there is. Here, at least one of the inter-terminal voltages V <b> 1 and V <b> 2 exhibits an abnormal value when the pumping phenomenon occurs in the amplifier unit 1. In addition, the pumping phenomenon occurs particularly noticeably when the SP output 20 is in a short circuit state. Therefore, the short circuit determination device 3 substantially determines whether or not the pumping phenomenon occurs in the amplifier unit 1 based on the determination result of whether or not at least one of the inter-terminal voltages V1 and V2 shows an abnormal value. Can be determined. As a result, the short circuit determination device 3 can determine whether or not the SP output 18 is in a short circuit state based on the determination result of whether or not the pumping phenomenon occurs in the amplifier unit 1.

  Particularly in the present embodiment, when the short circuit determination device 3 determines whether or not the SP output 18 is in a short circuit state, an inspection signal generated by the short circuit determination device 3 is input to the SG input 11. That is, when the short circuit determination device 3 determines whether or not the SP output 18 is in a short circuit state, the SG input 11 is used to determine whether or not the SP output increase 20 is in a short circuit state. A special inspection signal is actively input. For this reason, in this embodiment, an audio signal that is normally input to the amplifier unit 1 (that is, an audio signal that may cause destruction of the amplifier unit 1 depending on its characteristics) is passively input to the SG input 11. Compared to the case where the amplifier section 1 is broken, destruction (for example, electrical destruction) of the amplifier unit 1 is preferably prevented.

  In the above description, the inspection signal generator 31 generates an AC signal having a predetermined frequency or less as the inspection signal. However, the test signal generator 31 may generate a DC signal as the test signal in addition to or instead of the AC signal having a predetermined frequency or lower. Also in this case, it is preferable that the controller 33 appropriately adjust the amplification factor of the preamplifier 12 so that the output signal level of the inspection signal becomes a specified signal level. Furthermore, it is preferable that the signal control unit 331 controls the inspection signal generator 31 so as to generate an inspection signal having an input signal level capable of setting the output signal level of the inspection signal to a specified signal level. Even when a DC signal is input as an inspection signal, a pumping phenomenon occurs in the amplifier unit 1 if the SP output 18 is in a short-circuited state. Therefore, the short circuit determination device 3 can preferably determine whether or not the SP output 18 is in a short circuit state.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and short-circuit determination accompanied by such changes The apparatus and the short circuit detection method are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Amplifier part 11 SG input 12 Preamplifier 13 Comparator 14 Power amplifier 15 Relay 16a, 16b Power supply 17a, 17b Capacitor 18 SP output 3 Short circuit determination apparatus 31 Inspection signal generator 32a, 32b Voltage detector 33 Controller 331 Signal control part 332 Short circuit determination Part 34 Relay drive circuit

Claims (4)

Generating means for generating a predetermined inspection signal used to determine whether or not the output terminal of the amplifier circuit is in a short-circuit state;
Detecting means for detecting a voltage value of a power source of the amplifier circuit while the inspection signal generated by the generator is being input to an input terminal of the amplifier circuit;
Determination means for determining whether or not the output terminal is in the short circuit state based on the voltage value detected by the detection means ; and
The amplifier circuit is a half-bridge type D amplifier,
The inspection signal is an AC signal having a frequency equal to or lower than a first frequency determined according to a capacitance of a capacitor attached to the power source of the amplifier circuit,
The test signal has a signal level when it reaches the output terminal, and (i) the amplifier circuit is in a state where the output terminal is in the short-circuit state when the test signal is input to the input terminal. And (ii) a second signal level capable of suppressing destruction of the amplifier circuit due to the input of the inspection signal to the input terminal. shorting determination and wherein the at. The inspection signal is an AC signal having a second frequency capable of causing the amplifier circuit to generate a pumping phenomenon when the inspection signal is input to the input terminal in a state where the output terminal is in the short circuit state. short determination apparatus according to claim 1, characterized in that. The test signal is an alternating current in which the signal level of the test signal when the test signal reaches the output terminal is equal to or lower than a first signal level determined according to the capacitance of the capacitor associated with the power supply of the amplifier circuit. A signal is included. The short circuit determination apparatus as described in any one of Claim 1 and 2 characterized by the above-mentioned. A generating step for generating a predetermined inspection signal used to determine whether or not the output terminal of the amplifier circuit is in a short-circuit state;
A detection step of detecting a voltage value of a power source of the amplification circuit while the inspection signal generated in the generation step is input to an input terminal of the amplification circuit;
A determination step of determining whether or not the output terminal is in the short-circuit state based on the voltage value detected in the detection step, and
The amplifier circuit is a half-bridge type D amplifier,
The inspection signal is an AC signal having a frequency equal to or lower than a first frequency determined according to a capacitance of a capacitor attached to the power source of the amplifier circuit,
The test signal has a signal level when it reaches the output terminal, and (i) the amplifier circuit is in a state where the output terminal is in the short-circuit state when the test signal is input to the input terminal. And (ii) a second signal level capable of suppressing destruction of the amplifier circuit due to the input of the inspection signal to the input terminal. A method of detecting a short circuit, wherein:

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