Delay shutdown circuit and record player

Abstract

The invention provides a time-delay shutdown circuit and a record player, and the circuit comprises a detection unit which is coupled with a time-delay unit and is configured to detect the state of an audio signal and output a corresponding detection signal; the time delay unit is respectively coupled with the comparison unit and the first voltage source and is configured to respond to the state change of the detection signal, change the charging duration of the first voltage source and output corresponding charging voltage to the first input end of the comparison unit; the comparison unit is coupled with the gating unit, a second input end of the comparison unit is provided with a preset voltage threshold value, and the comparison unit is configured to output a comparison signal to the gating unit according to the charging voltage and the preset voltage threshold value; and the gating unit is respectively coupled with the power amplifier circuit, the second voltage source and the power supply voltage, and is configured to disconnect a conductive path between the power supply voltage and the power amplifier circuit based on the second voltage source when the gating unit is gated according to the comparison signal. By adopting the technical scheme, delayed turn-off without signals is realized, and the service life of the power amplifier circuit can be prolonged.

Description

Technical Field

[0001] The present invention relates to the field of circuit technologies, and in particular, to a delay shutdown circuit and a record player. Background Art

[0002] A power amplifier circuit (also known as an audio power amplifier) is an electronic device used to amplify audio signals. Its main function is to amplify the low-level audio signals from a sound source (such as a record player) to high-level signals sufficient to drive a speaker. The power amplifier plays an important role in an audio system and is usually used together with a sound source device and a speaker to achieve high-quality audio playback.

[0003] In some application scenarios, when there is no audio signal input from the sound source, the power amplifier circuit is still in an operating state, which will reduce the service life of the power amplifier circuit. Summary of the Invention

[0004] In view of this, the present invention provides a delay shutdown circuit and a record player, which achieve delayed shutdown without a signal and can improve the service life of the power amplifier circuit.

[0005] The present invention provides an operational amplifier circuit, including: a detection unit, a delay unit, a comparison unit, and a gating unit, where:

[0006] The detection unit is coupled to the delay unit and is configured to detect the state of an audio signal and output a corresponding detection signal;

[0007] The delay unit is respectively coupled to the comparison unit and a first voltage source, and is configured to change the charging duration of the first voltage source in response to a change in the state of the detection signal, so as to output a corresponding charging voltage to the first input terminal of the comparison unit;

[0008] The comparison unit is coupled to the gating unit, and a second input terminal of the comparison unit has a preset voltage threshold, and is configured to output a comparison signal to the gating unit according to the charging voltage and the preset voltage threshold;

[0009] The gating unit is respectively coupled to a power amplifier circuit, a second voltage source, and a power supply voltage, and is configured to, when being gated according to the comparison signal, based on the second voltage source, disconnect the conduction path between the power supply voltage and the power amplifier circuit.

[0010] Optionally, the delay unit includes: a pull-down module, which is configured to be in an off state when the detection signal is in a first state; and is configured to be in an on state when the detection signal is in a second state;

[0011] A voltage supply module, configured to provide a first voltage division coefficient by itself when the pull-down module is in an off state, and perform an energy storage operation based on the first voltage source and the first voltage division coefficient to generate a charging voltage with a first amplitude; and when the pull-down module is in an on state, interact with the pull-down module to provide a second voltage division coefficient, and perform an energy storage operation based on the first voltage source and the second voltage division coefficient to generate a charging voltage with a second amplitude, wherein the first amplitude is greater than the preset voltage threshold, and the second amplitude is less than the preset voltage threshold.

[0012] Optionally, the delay unit satisfies at least one or more of the following:

[0013] The pull-down module includes: a pull-down resistor and a pull-down transistor. The control end of the pull-down transistor is coupled to the detection unit. The first end of the pull-down transistor is coupled to the second end of the pull-down resistor. The second end of the pull-down transistor is grounded. The first end of the pull-down resistor is respectively coupled to the first input end of the comparison unit and the voltage supply module;

[0014] The voltage supply module includes: an energy storage capacitor, a first voltage division resistor, and a second voltage division resistor. Wherein, the first end of the energy storage capacitor is respectively coupled to the first end of the first voltage division resistor, the first end of the second voltage division resistor, the pull-down module, and the first end of the comparison unit. The second end of the energy storage capacitor is grounded. The second end of the first voltage division resistor is connected to the first voltage source. The second end of the second voltage division resistor is grounded;

[0015] A discharge diode. The first end of the discharge diode is respectively coupled to the pull-down module and the first input end of the comparison unit. The second end of the discharge diode is coupled to the first voltage source;

[0016] Wherein, the first voltage division resistor and the second voltage division resistor are used to determine the first voltage division coefficient, and the first voltage division resistor and the pull-down resistor are used to determine the second voltage division coefficient.

[0017] Optionally, the detection unit includes:

[0018] A comparison module. The first end of the comparison module is adapted to receive the audio signal. The output end of the comparison module is coupled to the delay unit;

[0019] A feedback module, respectively coupled to the second end and the output end of the comparison module, for detecting the detection signal output by the comparison module and generating a corresponding feedback signal to the second end of the comparison module;

[0020] An enabling module, which is respectively coupled to the output end of the comparison module and the delay unit, is configured to perform voltage division processing on the detection signal to generate an enabling signal, and the enabling signal has a state consistent with the detection signal.

[0021] Optionally, the detection unit satisfies one or more of the following:

[0022] The comparison module includes a first operational amplifier. The non-inverting input terminal of the first operational amplifier serves as the first terminal, the inverting input terminal of the first operational amplifier serves as the second terminal, and the output terminal of the first operational amplifier serves as the output terminal of the comparison module;

[0023] The feedback module includes: a first feedback resistor, a second feedback resistor, and a feedback capacitor. Among them, the first end of the first feedback resistor is respectively coupled to the second end of the comparison module and the first end of the second feedback resistor, the second end of the first feedback resistor is coupled to the first end of the feedback capacitor; the second end of the feedback capacitor is grounded; the second end of the second feedback resistor is coupled to the output end of the comparison module;

[0024] The driving module includes: a rectifying diode, a first enabling resistor, and a second enabling resistor. Among them, the first end of the rectifying diode is coupled to the output end of the comparison module, and the second end of the rectifying diode is coupled to the first end of the first enabling resistor; the second end of the first enabling resistor is respectively coupled to the delay unit and the first end of the second enabling resistor; the second end of the second enabling resistor is grounded.

[0025] Optionally, the comparison unit includes: a second operational amplifier. The non-inverting input terminal of the second operational amplifier serves as the first input terminal of the comparison unit, the inverting input terminal of the second operational amplifier serves as the second input terminal of the comparison unit, and the output terminal of the second operational amplifier is coupled to the gating unit.

[0026] Optionally, the gating unit includes: a gating module and a relay. Among them: the gating module, which is respectively coupled to the output end of the comparison unit and the relay, is configured to, in response to the comparison signal, when in the gating state, through the relay, gate the path between the second voltage source and the ground, thereby disconnecting the conductive path between the power supply voltage and the power amplifier circuit; and is configured to, in response to the comparison signal, when in the disconnected state, disconnect the path between the second voltage source and the ground, thereby gating the conductive path between the power supply voltage and the power amplifier circuit.

[0027] Optionally, the gating unit satisfies one or more of the following:

[0028] The gating module includes: a gating transistor, the control end of the gating transistor is coupled to the output end of the comparison unit, the first end of the gating transistor is coupled to the relay, and the second end of the gating transistor is grounded;

[0029] The first pin of the relay is coupled to the gating module, the second pin is coupled to the second voltage source, the fifth and seventh pins are coupled to the power amplifier circuit, and the sixth and eighth pins are adapted to input the power supply voltage;

[0030] And a freewheeling diode, the freewheeling diode is coupled between the first pin and the second pin.

[0031] Optionally, the delayed shutdown circuit further includes: a voltage dividing unit, respectively coupled to the first voltage source and the second input end of the comparison unit, configured to divide the voltage of the first voltage source to obtain the preset threshold voltage; wherein, the voltage dividing unit includes: a third voltage dividing resistor and a fourth voltage dividing resistor, wherein, the first end of the third voltage dividing resistor is coupled to the first voltage source, the second end of the third voltage dividing resistor is respectively coupled to the first end of the fourth voltage dividing resistor and the second input end of the comparison unit; the second end of the fourth voltage dividing resistor is grounded;

[0032] A current limiting unit, coupled to the output end of the comparison unit and the gating unit, includes: a current limiting diode, a current limiting resistor and a current limiting capacitor, wherein, the first end of the current limiting diode is coupled to the output end of the comparison unit, the second end of the current limiting diode is respectively coupled to the first end of the current limiting resistor and the first end of the current limiting capacitor; the second end of the current limiting capacitor is grounded; the second end of the current limiting resistor is coupled to the gating unit.

[0033] Correspondingly, the present invention further provides a record player, including: the delayed shutdown circuit described in any one of the foregoing.

[0034] Compared with the prior art, the technical solution of the embodiment of the invention has the following advantages:

[0035] The delay shutdown circuit provided by the invention embodiment can output a corresponding detection signal by detecting the state of the audio signal. This detection signal can indicate whether there is an audio signal. Furthermore, based on this state change, the charging duration of the first voltage source is changed, so that the charging voltage rises slowly. And the second input end of the comparison unit has a preset voltage threshold, so that a comparison signal for selecting or shutting off the selection unit can be output according to the charging voltage and the preset voltage threshold, and then the connection relationship between the power supply voltage and the power amplifier circuit is changed. In other words, at a certain moment after the audio signal disappears, the charging voltage is greater than the preset voltage threshold, and thus the connection relationship between the power supply voltage and the power amplifier circuit can be disconnected, so that the power amplifier circuit no longer works, realizing delay shutdown without signal and improving the service life of the power amplifier circuit. Brief Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0037] Figure 1 FIG. shows the structural schematic diagram of a delay shutdown circuit in an embodiment of the present invention;

[0038] Figure 2 FIG. shows the structural schematic diagram of a delay unit in an embodiment of the present invention;

[0039] Figure 3 FIG. shows the structural schematic diagram of a detection unit in an embodiment of the present invention;

[0040] Figure 4 FIG. shows the specific structural schematic diagram of a delay shutdown circuit in an embodiment of the present invention;

[0041] Figure 5 FIG. shows the structural schematic diagram of a switch unit in an embodiment of the present invention. Detailed Description of the Embodiments

[0042] As described in the background art, when there is no audio signal in the input sound source, the power amplifier circuit is still in an operating state, which will reduce the service life of the power amplifier circuit.

[0043] To solve the above technical problems, the present invention provides a delayed shutdown circuit. By detecting the state of an audio signal, it can output a corresponding detection signal, which can indicate whether there is an audio signal. Furthermore, based on this change in state, the charging duration of the first voltage source is changed, so that the charging voltage rises slowly. And the second input terminal of the comparison unit has a preset voltage threshold, so that a comparison signal for selecting or shutting off the selection unit can be output according to the charging voltage and the preset voltage threshold, thereby changing the connection relationship between the power supply voltage and the power amplifier circuit.

[0044] In other words, at a certain moment after the audio signal disappears, the charging voltage is greater than the preset voltage threshold, and thus the connection between the power supply voltage and the power amplifier circuit can be disconnected, so that the power amplifier circuit no longer works, realizing delayed shutdown without a signal, which can improve the service life of the power amplifier circuit.

[0045] To enable those skilled in the art to better understand and implement the present disclosure, the following refers to the accompanying drawings and details the specific solutions, principles, advantages, and effects of the present disclosure through specific embodiments.

[0046] See Figure 1 In the schematic structural diagram of a delayed shutdown circuit in an embodiment of the present invention shown in Figure 1 As shown, the delayed shutdown circuit 100 may include: a detection unit 110, a delay unit 120, a comparison unit 130, and a selection unit 140, where:

[0047] The detection unit 110 is coupled to the delay unit 120 and is configured to detect the state of the audio signal and output a corresponding detection signal;

[0048] The delay unit 120 is respectively coupled to the comparison unit 130 and the first voltage source U1, and is configured to change the charging duration of the first voltage source U1 in response to the change in the state of the detection signal, so as to output a corresponding charging voltage to the first input terminal of the comparison unit 130;

[0049] The comparison unit 130 is coupled to the selection unit 140, and the second input terminal of the comparison unit 130 has a preset voltage threshold, and is configured to output a comparison signal to the selection unit 140 according to the charging voltage and the preset voltage threshold;

[0050] The selection unit 140 is respectively coupled to the power amplifier circuit 10A, the second voltage source U2, and the power supply voltage U, and is configured to, when selected according to the comparison signal, disconnect the conduction path from the power supply voltage U to the power amplifier circuit 10A based on the second voltage source U2.

[0051] Combined with Figure 1, briefly describe the working principle of the delayed shutdown circuit 100 in this solution:

[0052] In response to the change in the state of the audio signal, the detection unit 110 can output a detection signal consistent with this state change. Thus, when the state of the audio signal changes, it can change the charging duration of the first voltage source U1 to the delay unit 120, which makes the charging voltage provided by the delay unit 120 to the first input terminal of the comparison unit 130 have different amplitudes, and this charging voltage changes with the charging duration.

[0053] That is: the charging voltage does not change suddenly, and the preset voltage threshold at the second input terminal of the comparison unit 130 is a fixed value. In this way, under different states of the audio signal, the charging voltage and the preset voltage threshold have different relationships, so that the comparison signal output to the gating unit 140 has different states, thereby changing the on-off state of the gating unit 140, and further changing the operating state of the power amplifier circuit 10A.

[0054] In an application scenario, if the audio signal exists, at this time, in response to this audio signal, the detection signal output by the detection unit 110 has a second state (or it can be considered that the second state corresponds to the existence of the audio signal). Under the action of the detection signal, the first voltage source U1 has a second charging duration for the delay unit 120, so that the output charging voltage is less than the preset voltage threshold, and the power amplifier circuit works normally.

[0055] In an application scenario, if the audio signal does not exist, at this time, in response to this audio signal, the detection signal output by the detection unit 110 has a first state (or it can be considered that the first state corresponds to the non-existence of the audio signal). Under the action of the detection signal, the first voltage source U1 has a first charging duration for the delay unit 120 (it should be noted that the first charging duration and the second charging duration are different). At a certain moment, when the output charging voltage is greater than the preset voltage threshold, the gating unit 140 is in a gated state, and then the conductive path between the power supply voltage U and the power amplifier circuit 10A is disconnected, and the power amplifier circuit 10A stops working, thus realizing the delayed shutdown operation without signal.

[0056] It should be noted that, first, for the specific structure of the power amplifier circuit 10A in this solution, reference can be made to the existing power amplifier in the existing solution; second, the audio signal amplified by the power amplifier circuit 10A is the same audio signal as the audio signal detected by the detection unit 110.

[0057] In this embodiment, in combination with Figure 1 , refer to Figure 2 the structural schematic diagram of a delay unit in an embodiment of the present invention shown, as Figure 2 shown, the delay unit 120 includes:

[0058] The pull - down module 122 is configured to be in an off state when the detection signal is in the first state; and is configured to be in an on state when the detection signal is in the second state;

[0059] The voltage supply module 124 is configured to provide a first voltage division coefficient by itself when the pull - down module 122 is in an off state, and perform an energy storage operation based on the first voltage source U1 and the first voltage division coefficient to generate a charging voltage with a first amplitude; and when the pull - down module is in an on state, interact with the pull - down module 122, provide a second voltage division coefficient, and perform an energy storage operation based on the first voltage source U1 and the second voltage division coefficient to generate a charging voltage with a second amplitude.

[0060] Specifically, the state of the detection signal reflects the presence or absence of an audio signal. For example, the detection signal has a first state indicating the absence of an audio signal and a second state indicating the presence of an audio signal. Thus, based on the state of the detection signal, the on - off of the pull - down module 122 can be controlled.

[0061] Furthermore, when the detection signal is in the first state, the pull - down module 122 is in an off state, so the pull - down module 122 does not function. At this time, only the voltage supply module 124 operates, and the voltage supply module 124 provides a first voltage division coefficient. Then, an energy storage operation is performed based on the first voltage source U1 and the first voltage division coefficient to generate a charging voltage with a first amplitude.

[0062] That is: the first voltage division coefficient determines the amplitude output to the comparison unit 130, and the larger the first voltage division coefficient, the longer the charging duration. Correspondingly, the first amplitude is larger.

[0063] As the charging duration increases, the charging voltage with the first amplitude can be greater than the preset voltage threshold, so that the power amplifier circuit 10A stops working.

[0064] When the detection signal is in the second state, the pull - down module 122 is in an on state. Then, the pull - down module 122 acts together with the pull - down module 122 and provides a second voltage division coefficient (less than the first voltage division coefficient). At this time, an energy storage operation is performed based on the first voltage source U1 and the second voltage division coefficient to generate a charging voltage with a second amplitude.

[0065] Since the second voltage division coefficient is less than the first voltage division coefficient, as the charging duration increases, the charging voltage with the second amplitude is also less than the preset voltage threshold, so that the power amplifier circuit 10A operates normally.

[0066] In other words, the first amplitude is greater than the preset voltage threshold, and the second amplitude is less than the preset voltage threshold.

[0067] Thus, by responding to the change in the state of the detection signal, the change in the voltage division coefficient is achieved, thereby changing the charging duration, and then realizing the signal-free delay turn-off in one of the application examples; moreover, through this form of circuit, it is also possible to detect whether there is an audio signal.

[0068] In this embodiment, in combination with Figure 1 and Figure 2 , the delay unit 120 satisfies at least one or more of the following:

[0069] The pull-down module 122 may include: a pull-down resistor R21 and a pull-down transistor Q1. The control end of the pull-down transistor Q1 is coupled to the detection unit 110. The first end of the pull-down transistor Q1 is coupled to the second end of the pull-down resistor R21. The second end of the pull-down transistor Q1 is grounded; the first end of the pull-down resistor R21 is respectively coupled to the first input end of the comparison unit 130 and the voltage supply module 124.

[0070] In other words, when the pull-down module 122 is in the gated state (i.e., when the pull-down transistor Q1 is turned on), the pull-down resistor R21 is connected into the path from the first voltage source U1 to the ground to provide a second voltage division coefficient, so that the first voltage source U1 has a second action duration and the charging voltage is less than the preset voltage threshold.

[0071] When the pull-down module 122 is in the off state (i.e., when the pull-down transistor Q1 is turned off), the pull-down resistor R21 is disconnected to provide a first voltage division coefficient, so that the first voltage source U1 has a first action duration and the charging voltage is greater than the preset voltage threshold.

[0072] The voltage supply module 124 may include: a storage capacitor C2, a first voltage division resistor R22, and a second voltage division resistor R23. Wherein, the first end of the storage capacitor C2 is respectively coupled to the first end of the first voltage division resistor R22, the first end of the second voltage division resistor R23, the pull-down module 122, and the first input end of the comparison unit 130. The second end of the storage capacitor C2 is grounded; the second end of the first voltage division resistor R22 is connected to the first voltage source U1; the second end of the second voltage division resistor R23 is grounded.

[0073] In other words, when the pull-down module 122 is in the gated state, based on the first voltage division resistor R22 and the pull-down resistor R21, the second voltage division coefficient is determined; when the pull-down module 122 is in the off state, based on the first voltage division resistor R22 and the second voltage division resistor R23, the first voltage division coefficient is provided.

[0074] More specifically, when the pull-down transistor Q1 is turned on (at this time, there is an audio signal correspondingly), a path of U1 - R22 - R21 - Q1 - ground is formed, so that the voltage drop across the energy storage capacitor C2 is the voltage division on the pull-down resistor R21, and the voltage drop across the energy storage capacitor C2 is relatively small. In this way, when the energy storage capacitor C2 is charged by the first voltage source U1, the voltage on the energy storage capacitor C2 is always less than the preset voltage threshold, and the power amplifier circuit works normally.

[0075] When the pull-down transistor Q1 is turned off (at this time, there is no audio signal correspondingly), a path between U1 - R22 - R23 - ground is formed, so that the voltage drop across the energy storage capacitor C2 is the voltage division of the second voltage division resistor R23, and the voltage drop across the energy storage capacitor C2 is relatively large. In this way, when the energy storage capacitor C2 is charged by the first voltage source U1, at a certain moment, the voltage on the energy storage capacitor C2 is greater than the preset voltage threshold, and the power amplifier circuit stops working.

[0076] That is: the first voltage division resistor R22 and the second voltage division resistor R22 are used to determine the first voltage division coefficient, and the first voltage division resistor R22 and the pull-down resistor R21 are used to determine the second voltage division coefficient.

[0077] In some embodiments, the delay unit 120 further has a discharge diode D2. The first end of the discharge diode D2 is respectively coupled to the pull-down module 122 and the first input end of the comparison unit 130, and the second end of the discharge diode D2 is coupled to the first voltage source U1.

[0078] Thus, the discharge diode D2 can provide a discharge path when the pull-down module 122 is in the off state to improve the operation stability of the delay unit 120.

[0079] In this embodiment, in combination with Figure 1 and Figure 2 , referring to Figure 3 a schematic structural diagram of a detection unit in an embodiment of the present invention shown in Figure 3 as shown, the detection unit 110 may include:

[0080] A comparison module 112, the first end of the comparison module 112 is adapted to receive the audio signal, and the output end of the comparison module is coupled to the delay unit 120;

[0081] A feedback module 114, which is respectively coupled to the second end and the output end of the comparison module 112, is used to detect the detection signal output by the comparison module 112, and generate a corresponding feedback signal to the second end of the comparison module 112;

[0082] The enabling module 116 is respectively coupled to the output end of the comparison module 112 and the delay unit 120, and is configured to perform voltage division processing on the detection signal to generate an enabling signal, and the enabling signal has a state consistent with the detection signal.

[0083] In other words, through the interaction between the feedback module 114, the comparison module 112, and the enabling module 116, a detection signal consistent with the state of the audio signal can be output, so that the delay unit 120 has different charging durations.

[0084] More specifically, by comparing the magnitude relationship between the audio signal and the detection signal provided by the feedback module 114, a detection signal with a first state and a second state is provided.

[0085] For example, when the audio signal is less than the detection signal, it indicates that there is no audio signal, and thus the detection signal has a first state (corresponding to a low level "0"); when the audio signal is greater than the detection signal, it indicates that there is an audio signal, and thus the detection signal has a second state (corresponding to a high level "1").

[0086] It should be noted that the audio signal has a voltage value, and "the presence or absence of the audio signal mentioned in this solution can both refer to whether the voltage value of the audio signal can be detected".

[0087] In this embodiment, the detection unit 110 satisfies one or more of the following:

[0088] The comparison module 112 includes a first operational amplifier A1. The non-inverting input terminal of the first operational amplifier serves as the first terminal, the inverting input terminal of the first operational amplifier serves as the second terminal, and the output terminal of the first operational amplifier serves as the output terminal of the comparison module 112.

[0089] The feedback module 114 includes: a first feedback resistor R12, a second feedback resistor R13, and a feedback capacitor C1. Wherein, the first end of the first feedback resistor R12 is respectively coupled to the second end of the comparison module and the first end of the second feedback resistor R13. The second end of the first feedback resistor R12 is coupled to the first end of the feedback capacitor C1. The second end of the feedback capacitor C1 is grounded. The second end of the second feedback resistor R13 is coupled to the output end of the comparison module 112.

[0090] The enabling module 116 includes a rectifying diode D1, a first enabling resistor R14, and a second enabling resistor R15. Among them, the first end of the rectifying diode D1 is coupled to the output end of the comparison module 112, and the second end of the rectifying diode D1 is coupled to the first end of the first enabling resistor R14; the second end of the first enabling resistor R14 is respectively coupled to the delay unit 120 and the first end of the second enabling resistor R15; the second end of the second enabling resistor R15 is grounded.

[0091] Among them, the rectifying diode D1 is used to rectify the detection signal in the AC state or the changing state. The detection signal rectified by the rectifying diode D1 controls the conduction and cut-off of the pull-down transistor Q1.

[0092] The first enabling resistor R14 and the second enabling resistor R15 play a role of voltage division and enabling to provide a driving voltage for the pull-down transistor Q1.

[0093] Furthermore, the detection unit 110 may further include a matching resistor R11, and the matching resistor R11 performs impedance matching on the audio signal.

[0094] In this embodiment, referring to Figure 4 the specific structural schematic diagram of a delay shutdown circuit in an embodiment of the present invention shown in Figure 4 as shown, the comparison unit 130 may include: a second operational amplifier A2. The non-inverting input terminal of the second operational amplifier A2 serves as the first input terminal of the comparison unit 130, and the inverting input terminal of the second operational amplifier A2 serves as the second input terminal of the comparison unit. The output terminal of the second operational amplifier A2 is coupled to the gating unit 140.

[0095] Specifically, the preset voltage threshold at the inverting input terminal of the second operational amplifier A2 is a certain value, while the charging voltage at the non-inverting input terminal of the second operational amplifier A2 will change. Thus, when the charging voltage is greater than the preset voltage threshold, the output comparison signal can gate the gating unit 140, and further the power amplifier circuit 10A stops working.

[0096] More specifically, when there is an audio signal, the charging voltage is less than the preset voltage threshold, and further the comparison signal is at a low level "0", the gating unit 140 is disconnected, and the power amplifier circuit 10A works normally; when there is no audio signal, at a certain moment, the charging voltage is greater than the preset voltage threshold, and further the comparison signal is at a high level "1", the gating unit 140 is gated, and the power amplifier circuit 10A stops working.

[0097] In this embodiment, then referring to Figure 4, the delay shutdown circuit 100 may further include: a voltage dividing unit 150, respectively connected to the first voltage source U1 and the second input terminal of the comparison unit 130, configured to divide the voltage of the first voltage source U1 to obtain the preset threshold voltage Vref.

[0098] In other words, both the charging voltage and the preset threshold voltage Vref are obtained based on the first voltage source U1.

[0099] Wherein, the voltage dividing unit 150 may include: a third voltage dividing resistor R51 and a fourth voltage dividing resistor R52. The first end of the third voltage dividing resistor R51 is coupled to the first voltage source U1, and the second end of the third voltage dividing resistor R51 is respectively coupled to the first end of the fourth voltage dividing resistor R52 and the second input terminal of the comparison unit 130; the second end of the fourth voltage dividing resistor R52 is grounded.

[0100] Thus, the preset threshold voltage Vref is the voltage drop across the fourth voltage dividing resistor R52. And by obtaining the preset threshold voltage Vref through voltage division, the value of the preset threshold voltage Vref can be changed based on the actual application scenario, so that the delay shutdown circuit 100 can be applied to more scenarios.

[0101] In an alternative embodiment, the first voltage source U1 is 12V, and the resistance values of the third voltage dividing resistor R51 and the fourth voltage dividing resistor R52 are the same. Thus, the preset threshold voltage Vref is 6V.

[0102] In some embodiments, the second operational amplifier A2 can also be powered by a third voltage source U3, wherein the third voltage source U3 has the same amplitude as the first voltage source U1 but opposite in direction.

[0103] In this embodiment, the gating unit 140 includes: a gating module 142 and a relay 144, wherein: the gating module 142 is respectively coupled to the output terminal of the comparison unit 130 and the relay 144, and is configured to, in response to the comparison signal and when in the gating state, through the relay 144, gate the path between the second voltage source U2 and the ground, thereby disconnecting the conductive path between the power supply voltage U and the power amplifier circuit 10A; and is configured to, in response to the comparison signal and when in the off state, disconnect the path between the second voltage source U2 and the ground, thereby gating the conductive path between the power supply voltage U and the power amplifier circuit 10A.

[0104] That is, when the gating module 142 is gated (at this time, the pull-down module 122 is turned off, that is, the pull-down transistor Q1 is turned off), the power amplifier circuit 10A stops working; when the gating module 142 is turned off (at this time, the pull-down module 122 is gated, that is, the pull-down transistor Q1 is turned on), the power amplifier circuit 10A works normally.

[0105] In other words, the on / off state of the gating module 142 is opposite to that of the pull-down module 122.

[0106] In this embodiment, the gating unit 140 satisfies one or more of the following:

[0107] The gating module 142 may include: a gating transistor Q2, the control end of the gating transistor Q2 is coupled to the output end of the comparison unit 130, the first end of the gating transistor Q2 is coupled to the relay 144, and the second end of the gating transistor Q2 is grounded.

[0108] The first pin 1 of the relay 144 is coupled to the gating module 142, the second pin 2 is coupled to the second voltage source U2, the fifth pin 5 and the seventh pin 7 are coupled to the power amplifier circuit 10A, and the sixth pin 6 and the eighth pin 8 are adapted to input the power supply voltage.

[0109] Specifically, in the initial state, the eighth pin 8 and the seventh pin 7 are electrically connected, the sixth pin 6 and the fifth pin 5 are electrically connected, and the power supply voltage U can supply power to the operational amplifier circuit 10A through the relay 144, so that the operational amplifier circuit 10A can amplify the audio signal.

[0110] When the gating transistor Q2 is in the off state, the above connection relationship is still maintained; when the gating transistor Q2 is in the gating state, the first pin 1, the second pin 2, and the gating transistor Q2 are all grounded, so that the eighth pin 8 and the third pin 3 are electrically connected, the sixth pin 6 and the fourth pin 4 are electrically connected, and the conduction path between the power supply voltage U and the operational amplifier circuit 10A is disconnected, and the operational amplifier circuit 10A stops working.

[0111] In this embodiment, when the gating transistor Q2 is in the gating state, the coil of the relay 144 is powered off, and the energy in the coil needs to be released to protect the gating transistor Q2 from being broken down by the back electromotive force.

[0112] Therefore, the gating unit 140 may further include: a freewheeling diode D4, and the freewheeling diode D4 is coupled between the first pin 1 and the second pin 2.

[0113] In some embodiments, the delayed shutdown circuit may further include: a current limiting unit (not shown in the figure), coupled to the output end of the comparison unit 130 and the gating unit 140, including: a current limiting diode D3, a current limiting resistor R31, and a current limiting capacitor C3. Wherein, the first end of the current limiting diode D3 is coupled to the output end of the comparison unit 130, and the second end of the current limiting diode D3 is respectively coupled to the first end of the current limiting resistor R31 and the first end of the current limiting capacitor C3; the second end of the current limiting capacitor C3 is grounded; the second end of the current limiting resistor R31 is coupled to the gating unit 140.

[0114] For ease of understanding, briefly describe the working mechanism of the delayed shutdown circuit in this solution through Figure 4 , as follows.

[0115] When there is an audio signal, the detection signal output by the first operational amplifier A1 is at a high level "1", so that the pull-down transistor Q1 is turned on, thereby forming a path of the first voltage source U1 - the first voltage-dividing resistor R22 - the pull-down resistor R21 - the pull-down transistor Q1 - ground, so that the voltage drop across the energy storage capacitor C2 is the voltage value of the pull-down resistor R21, which is less than the preset voltage threshold.

[0116] The comparison signal output by the second operational amplifier A2 is at a low level "0", then the gating transistor Q2 is in an off state, and the operational amplifier circuit 10A is in a working state.

[0117] When there is no audio signal, the detection signal output by the first operational amplifier A1 is at a low level "0", so that the pull-down transistor Q1 is turned off, thereby forming a path of the first voltage source U1 - the first voltage-dividing resistor R22 - the second voltage-dividing resistor R23 - ground, so that the voltage drop across the energy storage capacitor C2 is the voltage value of the second voltage-dividing resistor R23.

[0118] As the charging progresses, the voltage across the energy storage capacitor C2 is greater than the preset voltage threshold, so that the comparison signal output by the second operational amplifier A2 is at a high level "1", then the gating transistor Q2 is in a gated state, and the operational amplifier circuit 10A does not work. Thus, the automatic shutdown function after a period of no signal is realized.

[0119] During the actual use process, the inventor further found that when receiving the audio signal again, it is also possible to control whether to connect the audio signal to the delayed shutdown circuit.

[0120] Correspondingly, the delayed shutdown circuit in this solution may further include: a switch unit, coupled to the detection unit, configured to, when receiving the audio signal, select the path between the audio signal and the detection unit by switching the state of the control switch.

[0121] Specifically, when the audio signal is output normally, the control switch can be used to provide the audio signal to the detection unit. When the audio signal is absent, the control switch is in an open state. When the audio signal is received again, the state of the switch unit is switched to select and connect the path between the audio signal and the detection unit.

[0122] In this embodiment, refer to Figure 5 the schematic structural diagram of a switch unit in an embodiment of the present invention as shown in Figure 5 As shown, the switch unit (not marked in the figure) may include: a control branch composed of a fifth voltage-dividing resistor R61, a sixth voltage-dividing resistor R63, a seventh voltage-dividing resistor R64, and a control switch K1; a selection branch composed of a selection switch K2 and a bidirectional thyristor S; and an energy storage branch composed of an energy storage resistor R62, a diode D5, and a capacitor C4.

[0123] Among them, the first end of the fifth voltage-dividing resistor R61 is adapted to receive the audio signal and is coupled to the first end of the bidirectional thyristor S, and the second end of the fifth voltage-dividing resistor R61 is coupled to the first end of the control switch K1; the second end of the control switch K1 is respectively coupled to the first end of the selection switch K2, the first end of the sixth voltage-dividing resistor R63, and the first end of the seventh voltage-dividing resistor R65; the second end of the selection switch K2 is coupled to the second end of the bidirectional thyristor S, and the selection switch K2 also has a third end; the second end of the sixth voltage-dividing resistor R63 is respectively coupled to the second end of the diode D5 and the first end of the capacitor C1; the second end of the seventh voltage-dividing resistor R64 is coupled to the second end of the capacitor C1 and is grounded; the third end of the bidirectional thyristor S is respectively coupled to the first end of the energy storage resistor R62 and the detection unit 110; the second end of the energy storage resistor R62 is coupled to the first end of the diode D5.

[0124] More specifically, when the first end of the fifth voltage-dividing resistor R61 receives the audio amplification signal, the control switch K1 is pressed (it should be noted that after the control switch K1 is pressed, it returns to the initial state), then under the voltage-dividing action of the fifth voltage-dividing resistor R61 and the seventh voltage-dividing resistor R64, a first trigger voltage is provided to the selection switch K2, and then the bidirectional thyristor S is in a conducting state, and the audio amplification signal can be output to the detection unit 110.

[0125] Meanwhile, the audio amplification signal can also charge the capacitor C4 through the energy storage resistor R62 and the diode D5. In this way, during the negative half-cycle of the audio amplification signal, the capacitor C4 can continuously output a second trigger voltage to the selection switch K2 through the sixth voltage-dividing resistor R63 and the seventh voltage-dividing resistor R64, and the bidirectional thyristor S is in a conducting state.

[0126] When the audio amplification signal suddenly disappears, the bidirectional thyristor switch S is in the off state. When the audio amplification signal is received again, since the control switch K1 is not triggered, the bidirectional thyristor switch S remains in the off state.

[0127] After a period of time, when the audio amplification signal is stable, press the control switch K1, and the bidirectional thyristor switch S can be turned on in the manner of the foregoing example to output the audio amplification signal to the detection unit 110, thereby improving the working stability of the entire circuit.

[0128] It can be understood that the above describes multiple embodiment solutions provided by the embodiments of the present disclosure. The optional methods described in each embodiment solution can be combined with each other and cross-referenced without conflict, so as to extend a variety of possible embodiment solutions, all of which can be considered as the embodiment solutions disclosed and made public by the present disclosure.

[0129] The present invention also provides a record player, which may include: the delay shutdown circuit described in any of the foregoing embodiments.

[0130] Although the embodiments of the present disclosure are disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A delayed shutdown circuit, characterized in that, Comprising: A detection unit, a delay unit, a comparison unit, and a gating unit, wherein: The detection unit, coupled to the delay unit, is configured to detect the state of an audio signal and output a corresponding detection signal; The delay unit, coupled to the comparison unit and a first voltage source respectively, is configured to change the charging duration of the first voltage source in response to a change in the state of the detection signal, so as to output a corresponding charging voltage to a first input terminal of the comparison unit; The comparison unit, coupled to the gating unit, and a second input terminal of the comparison unit has a preset voltage threshold, and is configured to output a comparison signal to the gating unit according to the charging voltage and the preset voltage threshold; The gating unit, coupled to a power amplifier circuit, a second voltage source, and a power supply voltage respectively, is configured to, according to the comparison signal, when being gated, based on the second voltage source, disconnect the conduction path between the power supply voltage and the power amplifier circuit.

2. The delay-off circuit according to claim 1, wherein The delay unit includes: A pull-down module, configured to be in an off state when the detection signal is in a first state; and configured to be in an on state when the detection signal is in a second state; A voltage providing module, configured to, when the pull-down module is in an off state, provide a first voltage division coefficient by itself, and perform an energy storage operation based on the first voltage source and the first voltage division coefficient to generate a charging voltage with a first amplitude; and when the pull-down module is in an on state, interact with the pull-down module to provide a second voltage division coefficient, and perform an energy storage operation based on the first voltage source and the second voltage division coefficient to generate a charging voltage with a second amplitude, wherein the first amplitude is greater than the preset voltage threshold, and the second amplitude is less than the preset voltage threshold.

3. The delayed shutdown circuit according to claim 2, characterized in that, The delay unit satisfies at least one or more of the following: The pull-down module includes: a pull-down resistor and a pull-down transistor, a control terminal of the pull-down transistor is coupled to the detection unit, a first end of the pull-down transistor is coupled to a second end of the pull-down resistor, and a second end of the pull-down transistor is grounded; a first end of the pull-down resistor is coupled to the first input terminal of the comparison unit and the voltage providing module respectively; The voltage providing module includes: an energy storage capacitor, a first voltage division resistor, and a second voltage division resistor, wherein a first end of the energy storage capacitor is coupled to a first end of the first voltage division resistor, a first end of the second voltage division resistor, the pull-down module, and a first end of the comparison unit respectively, a second end of the energy storage capacitor is grounded; a second end of the first voltage division resistor is connected to the first voltage source; a second end of the second voltage division resistor is grounded; A discharge diode, a first end of the discharge diode is coupled to the pull-down module and the first input terminal of the comparison unit respectively, and a second end of the discharge diode is coupled to the first voltage source; Wherein, the first voltage division resistor and the second voltage division resistor are used to determine the first voltage division coefficient, and the first voltage division resistor and the pull-down resistor are used to determine the second voltage division coefficient.

4. The delay shutdown circuit according to claim 1, wherein The detection unit includes: A comparison module, a first end of the comparison module is adapted to receive the audio signal, and an output end of the comparison module is coupled to the delay unit; A feedback module, which is respectively coupled to a second end and an output end of the comparison module, and is configured to detect a detection signal output by the comparison module and generate a corresponding feedback signal to the second end of the comparison module; An enabling module, which is respectively coupled to the output end of the comparison module and the delay unit, and is configured to perform voltage division processing on the detection signal to generate an enabling signal, and the enabling signal has a state consistent with the detection signal.

5. The delay-off circuit according to claim 4, wherein, The detection unit satisfies one or more of the following: The comparison module includes a first operational amplifier, a non-inverting input terminal of the first operational amplifier serves as the first end, an inverting input terminal of the first operational amplifier serves as the second end, and an output terminal of the first operational amplifier serves as the output end of the comparison module; The feedback module includes: a first feedback resistor, a second feedback resistor and a feedback capacitor. Wherein, a first end of the first feedback resistor is respectively coupled to the second end of the comparison module and a first end of the second feedback resistor, a second end of the first feedback resistor is coupled to a first end of the feedback capacitor; a second end of the feedback capacitor is grounded; a second end of the second feedback resistor is coupled to the output end of the comparison module; The enabling module includes: a rectifying diode, a first enabling resistor and a second enabling resistor. Wherein, a first end of the rectifying diode is coupled to the output end of the comparison module, a second end of the rectifying diode is coupled to a first end of the first enabling resistor; a second end of the first enabling resistor is respectively coupled to the delay unit and a first end of the second enabling resistor; a second end of the second enabling resistor is grounded.

6. The delayed shutdown circuit according to claim 1, wherein The comparison unit includes: a second operational amplifier, a non-inverting input terminal of the second operational amplifier serves as a first input terminal of the comparison unit, an inverting input terminal of the second operational amplifier serves as a second input terminal of the comparison unit, and an output terminal of the second operational amplifier is coupled to the gating unit.

7. The delay-off circuit according to claim 1, wherein The gating unit includes: a gating module and a relay, wherein: The gating module, which is respectively coupled to the output end of the comparison unit and the relay, and is configured to respond to the comparison signal. When in the gating state, through the relay, a conduction path between the second voltage source and the ground is gated, thereby disconnecting the conduction path between the power supply voltage and the power amplifier circuit; and is configured to respond to the comparison signal. When in the off state, the conduction path between the second voltage source and the ground is disconnected, thereby gating the conduction path between the power supply voltage and the power amplifier circuit.

8. The delay shutdown circuit according to claim 7, wherein The gating unit satisfies one or more of the following: The gating module includes: a gating transistor, a control end of the gating transistor is coupled to the output end of the comparison unit, a first end of the gating transistor is coupled to the relay, and a second end of the gating transistor is grounded; The first pin of the relay is coupled to the gating module, the second pin is coupled to the second voltage source, the fifth and seventh pins are coupled to the power amplifier circuit, and the sixth and eighth pins are adapted to input the power supply voltage; And a freewheeling diode, which is coupled between the first pin and the second pin.

9. The delayed shutdown circuit according to claim 1, wherein It further includes: A voltage dividing unit, which is respectively coupled to the first voltage source and the second input terminal of the comparison unit, and is configured to divide the voltage of the first voltage source to obtain the preset threshold voltage; wherein, the voltage dividing unit includes: a third voltage dividing resistor and a fourth voltage dividing resistor, wherein, the first end of the third voltage dividing resistor is coupled to the first voltage source, and the second end of the third voltage dividing resistor is respectively coupled to the first end of the fourth voltage dividing resistor and the second input terminal of the comparison unit; the second end of the fourth voltage dividing resistor is grounded; A current limiting unit, which is coupled to the output terminal of the comparison unit and the gating unit, and includes: a current limiting diode, a current limiting resistor and a current limiting capacitor, wherein, the first end of the current limiting diode is coupled to the output terminal of the comparison unit, and the second end of the current limiting diode is respectively coupled to the first end of the current limiting resistor and the first end of the current limiting capacitor; the second end of the current limiting capacitor is grounded; the second end of the current limiting resistor is coupled to the gating unit.

10. A record player, characterized in that, It includes: The delay shutdown circuit according to any one of claims 1 to 9.

Images