An active noise suppression circuit for audio switch

Abstract

The present invention discloses an active noise suppression circuit for audio switch, including a power-on control circuit, a power-on power supply circuit, a power-on delay circuit, a power-on switch circuit and a fast switch silencer circuit, wherein the power-on control circuit is connected to the power-on delay circuit, the power-on delay circuit is connected to the power-on power supply circuit, the power-on power supply circuit is connected to the input end connected to the fast switch silencer circuit, the fast switch silencer circuit is connected to the power-on switch circuit at node a, in fact, node a is used as the switch control signal output end; the input end of the fast switch silencer circuit is used to connect to alternating current. The present invention can realize active noise suppression during the device power-on and power-off process, ensuring stable operation of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of audio, and in particular to an active noise reduction circuit for audio switch. Background Art

[0002] Sound is one of the main ways for humans to communicate. Currently, humans have been conducting experiments to improve the hearing of sound. The sound source can be quantified, and after quantification, audio equipment can be used to extract sounds that are very real to human hearing, reduce distortion, and eliminate audio harmonic noise that is harmful to the hearing.

[0003] In the application of modern audio equipment, such as audio processors, CDs, DVDs, etc., these products use a large number of DSP digital algorithms combined with analog circuits to improve the quality of the sound source and make the audio sound quality better. However, the large number of applications of these circuits make the digital circuit or analog circuit have a stable circuit state process (generally within 5S) when the audio equipment is just powered on. This process may cause AC to DC noise, high-frequency noise when the digital circuit switches on and off, and popping noise when various digital control circuits switch on and off; in the process of shutting down the power of the audio equipment, since the power supply requires a large number of electrolytic capacitors, the power supply is normal and the power supply slowly decreases during the shutdown process, and the internal digital analog circuit suddenly loses power, causing the circuit to work abnormally and produce popping noise or other uncertain noise, which is often called "on and off impact sound" in the industry; this sound source input to the subsequent connection device will cause the internal input circuit voltage of the subsequent device to be high, the audio noise is chaotic, and the circuit is overcurrent and the power load is increased and burned out. The noise output from the speaker can easily cause hearing damage to the audience, which is very harmful. If the audio equipment's post-stage is equipped with a protection circuit, these uncertain audio "power-on and power-off impact sounds" will still damage the post-stage equipment, causing a high failure rate for the entire equipment, and high after-sales return transportation and repair costs. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention proposes an active noise reduction and suppression circuit for audio power on and off, which can achieve active noise reduction and suppression during the power on and off process of the device, thereby ensuring stable operation of the device.

[0005] The technical solution of the present invention is achieved in this way:

[0006] An active noise suppression circuit for audio power on and off, comprising a power on start control circuit, a power on start power supply circuit, a power on start delay circuit, a power on start switch tube circuit and a fast power on and off silencer circuit, wherein the power on start control circuit is connected to the power on start delay circuit, the power on start delay circuit is connected to the power on start power supply circuit, the power on start power supply circuit is connected to an input end connected to the fast power on and off silencer circuit, the fast power on and off silencer circuit is connected to the power on start switch tube circuit at node a, in fact, node a serves as a power on and off control signal output end; the input end of the fast power on and off silencer circuit is used to be connected to alternating current.

[0007] Furthermore, the fast power on / off silencing circuit includes a diode D1, a diode D2, a diode D3, a diode D4, a capacitor C1 and a resistor R1, the cathode of the diode D1 is connected to the first AC interface, the cathode of the diode D2 is connected to the second AC interface, the anode of the diode D1 and the anode of the diode D2 are connected to a node b; the cathode of the diode D3 is connected to the node b, the anode of the diode D3 is connected to the cathode of the diode D4; the anode of the diode D4 is connected in series with the resistor R1; one end of the capacitor C1 is connected to the node b, and the other end is grounded.

[0008] Furthermore, the power-on start switch tube circuit includes a resistor R3, a resistor R8, a resistor R9, a diode D8 and a transistor Q1, the cathode of the diode D8 is connected to the DC cathode, the anode of the diode D8 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to node a; the c pole of the transistor Q1 is connected to node a, the e pole of the transistor Q1 is connected to the DC positive pole, one end of the resistor R9 is connected to the b pole of the transistor Q1, and the other end of the resistor R9 is connected to the power-on start control circuit; one end of the resistor R3 is connected to the b pole of the transistor Q1, and the other end of the resistor R3 is connected to the DC positive pole.

[0009] Furthermore, the power-on delay circuit includes a resistor R2, a diode D7, a voltage-stabilizing diode WD1 and a capacitor C2, the cathode of the diode D7 is connected to the power-on power supply circuit, the anode of the diode D7 is connected to the cathode of the voltage-stabilizing diode WD1, and the anode of the diode D7 is connected to the power-on control circuit; one end of the resistor R2 is connected to the cathode of the diode D7, and the other end is connected to the anode of the diode D7; one end of the capacitor C2 is connected to the anode of the diode D7, and the other end is grounded.

[0010] Furthermore, the power-on startup power supply circuit includes a diode D5, a diode D6, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a capacitor C3, the positive electrode of the diode D6 is connected to the first AC power interface, the positive electrode of the diode D5 is connected to the second AC power interface, and the negative electrode of the diode D6 is connected to the negative electrode of the diode D5; one end of the capacitor C3 is connected to the negative electrode of the diode D6, and the other end is grounded; after the resistors R4, R5, R6 and R7 are connected in parallel respectively, one end is connected to the negative electrode of the diode D6, and the other end is grounded.

[0011] Further, the power-on start control circuit includes a transistor Q2, a transistor Q3, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a diode D9, a capacitor C4 and a photocoupler U1, wherein the c-pole of the transistor Q3 is connected to the DC positive pole; one end of the resistor R10 is connected to the c-pole of the transistor Q2, and the other end is connected to the b-pole of the transistor Q2; the positive pole of the diode D9 is connected to the b-pole of the transistor Q2, and the negative pole of the diode is connected to the c-pole of the transistor Q2; one end of the capacitor C4 is connected to the b-pole of the transistor One end of the resistor R11 is connected to the e-pole of the transistor Q2, and the other end is grounded; pin 1 of the photoelectric coupler is connected to the e-pole of the transistor Q2, pin 2 of the photoelectric coupler is connected in series with the resistor R12 and then grounded, pin 4 of the photoelectric coupler is connected to the power-on delay circuit, and pin 3 of the photoelectric coupler is connected to the b-pole of the transistor Q3; one end of the resistor R13 is connected to the b-pole of the transistor Q3, and the other end is grounded; the c-pole of the transistor Q3 is connected to the power-on start switch tube circuit, and the e-pole of the transistor Q3 is grounded.

[0012] Compared with the prior art, the present invention has the following advantages: by setting a power-on start control circuit, a power-on start power supply circuit, a power-on start delay circuit, a power-on start switch tube circuit and a fast power-on and power-off mute circuit, the present invention can effectively solve the impact noise of strong signals on the subsequent stage when the equipment is turned on and off or an emergency power outage occurs, and can achieve active noise suppression to achieve a normal listening effect; it can also effectively reduce the damage to the audio circuit and the harm to the human body caused by the impact sound of the audio equipment, avoid failure of the subsequent equipment, improve the satisfaction of the audience, reduce equipment damage, reduce the number of repairs, and save costs in various links such as after-sales. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0014] Figure 1 It is a structural block diagram of the active noise reduction suppression circuit of the audio switch of the present invention;

[0015] Figure 2 The present invention is a circuit diagram of an embodiment of an active noise suppression circuit for audio switch. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0018] See also Figure 1 The embodiment of the present invention discloses an active noise suppression circuit for audio power on and off, including a power on start-up control circuit, a power on start-up power supply circuit, a power on start-up delay circuit, a power on start-up switch tube circuit and a fast power on and off silencer circuit, wherein the power on start-up control circuit is connected to the power on start-up delay circuit, the power on start-up delay circuit is connected to the power on start-up power supply circuit, the power on start-up power supply circuit is connected to an input end connected to the fast power on and off silencer circuit, the fast power on and off silencer circuit is connected to the power on and off switch tube circuit at node a, in fact, node a is used as a power on and off control signal output end; the input end of the fast power on and off silencer circuit is used to be connected to alternating current.

[0019] In this embodiment, when the machine is turned on, the N-type MOS tube for controlling the output of the sound source is turned off by using a fast on / off mute circuit, and then the power-on start control circuit, the power-on start power supply circuit, and the power-on start delay circuit are used to delay for a certain period of time, and then the power-on start control circuit is used to control the power-on start switch tube circuit, so that the power-on start switch tube circuit controls the N-type MOS tube to be turned off and turned on; and when the machine is turned off, the N-type MOS tube for controlling the output of the sound source is turned off by using a fast on / off mute circuit. At this time, since the power-on start control circuit, the power-on start power supply circuit, and the power-on start delay circuit have no power supply, the N-type MOS tube is always in a cut-off state; the present invention can effectively solve the impact noise of a strong signal on the subsequent stage when the equipment is turned on and off or an emergency power outage occurs, and can realize active noise suppression to achieve a normal listening effect.

[0020] The fast power on / off silencing circuit includes a diode D1, a diode D2, a diode D3, a diode D4, a capacitor C1 and a resistor R1. The cathode of the diode D1 is connected to the first AC interface, the cathode of the diode D2 is connected to the second AC interface, the anode of the diode D1 and the anode of the diode D2 are connected to a node b; the cathode of the diode D3 is connected to the node b, the anode of the diode D3 is connected to the cathode of the diode D4; the anode of the diode D4 is connected in series with the resistor R1; one end of the capacitor C1 is connected to the node b, and the other end is grounded.

[0021] The power-on start switch tube circuit includes resistor R3, resistor R8, resistor R9, diode D8 and transistor Q1, the cathode of diode D8 is connected to the DC cathode, the anode of diode D8 is connected to one end of resistor R8, and the other end of resistor R8 is connected to node a; the c pole of transistor Q1 is connected to node a, the e pole of transistor Q1 is connected to the DC positive pole, one end of resistor R9 is connected to the b pole of transistor Q1, and the other end of resistor R9 is connected to the power-on start control circuit; one end of resistor R3 is connected to the b pole of transistor Q1, and the other end of resistor R3 is connected to the DC positive pole.

[0022] The power-on delay circuit includes a resistor R2, a diode D7, a voltage-stabilizing diode WD1 and a capacitor C2. The cathode of the diode D7 is connected to the power-on power supply circuit, the anode of the diode D7 is connected to the cathode of the voltage-stabilizing diode WD1, and the anode of the diode D7 is connected to the power-on control circuit; one end of the resistor R2 is connected to the cathode of the diode D7, and the other end is connected to the anode of the diode D7; one end of the capacitor C2 is connected to the anode of the diode D7, and the other end is grounded.

[0023] The power-on startup power supply circuit includes a diode D5, a diode D6, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a capacitor C3, wherein the positive electrode of the diode D6 is connected to the first AC power interface, the positive electrode of the diode D5 is connected to the second AC power interface, and the negative electrode of the diode D6 is connected to the negative electrode of the diode D5; one end of the capacitor C3 is connected to the negative electrode of the diode D6, and the other end is grounded; after the resistors R4, R5, R6 and R7 are connected in parallel respectively, one end is connected to the negative electrode of the diode D6, and the other end is grounded.

[0024] The power-on start control circuit includes transistor Q2, transistor Q3, resistor R10, resistor R11, resistor R12, resistor R13, diode D9, capacitor C4 and photoelectric coupler U1. The c pole of transistor Q3 is connected to the DC positive pole; one end of resistor R10 is connected to the c pole of transistor Q2, and the other end is connected to the b pole of transistor Q2; the positive pole of diode D9 is connected to the b pole of transistor Q2, and the negative pole of diode is connected to the c pole of transistor Q2; one end of capacitor C4 is connected to the b pole of transistor, and the other end is connected to the b pole of transistor Q2. end is grounded; one end of the resistor R11 is connected to the e-pole of the transistor Q2, and the other end is grounded; pin 1 of the photoelectric coupler is connected to the e-pole of the transistor Q2, pin 2 of the photoelectric coupler is connected in series with the resistor R12 and then grounded, pin 4 of the photoelectric coupler is connected to the power-on delay circuit, and pin 3 of the photoelectric coupler is connected to the b-pole of the transistor Q3; one end of the resistor R13 is connected to the b-pole of the transistor Q3, and the other end is grounded; the c-pole of the transistor Q3 is connected to the power-on start switch tube circuit, and the e-pole of the transistor Q3 is grounded.

[0025] When the power is turned on, the fast on / off mute circuit works first. Specifically, the fast on / off mute circuit takes power from the first AC interface and the second AC interface respectively, and rectifies through diodes D1 and D2 so that node b is a DC negative voltage (DC negative voltage), and uses capacitor C1 to filter out power lines to obtain a smooth DC negative voltage; the DC negative voltage at node b is output through a step-down circuit composed of diodes D3, D4 and resistor R1 to instantly output a negative voltage to control the N-type MOS tube QX to cut off, cutting off the path of the "on / off impact sound" at the moment of power on, thereby achieving power on noise suppression. In this embodiment, since the fast on / off mute circuit takes power directly from the AC, it can work within a few microseconds, and the processed signal of the sound source must be output through circuits such as input op amp, AD analog-to-digital, DSP signal processing, DA digital-to-analog conversion, and analog-to-electric output impedance matching. Before these circuits enter a stable working state, the fast on / off mute circuit preferentially cuts off its signal output path, thereby achieving active mute suppression at power on. After the fast power on / off mute circuit cuts off the signal output path of the sound source, it uses the power-on power supply circuit, power-on delay circuit, power-on control circuit and power-on switch tube circuit to open the signal output path of the sound source after the sound source processing circuit works stably, thereby effectively protecting the circuit of the subsequent equipment.

[0026] Specific:

[0027] The power-on power supply circuit takes AC power through the first AC interface and the second AC interface respectively, rectifies it into a DC positive voltage through diodes D4 and D5, and then filters the power ripple through capacitor C3, resistor R4, resistor R5, resistor R6, and resistor R7 to obtain a smooth positive DC voltage; the positive DC voltage is input into the power-on delay circuit, and charges capacitor C2 through resistor R2 and diode D7. Since the charging time of capacitor C2 is determined by resistor R2 and capacitor C2, a power-on delay RC circuit is formed; and the WD1 voltage regulator is used to give the power-on control circuit a threshold voltage set by a driver. When the voltage at node C reaches the voltage regulation value of the WD1 voltage regulator, the current will flow from the power-on delay circuit into the power-on control circuit.

[0028] For the power-on control circuit, when the power is turned on, the transistor Q2 cannot be turned on immediately due to the capacitor C4. After a period of time, the transistor Q3 is turned on after the capacitor C4 is fully charged, so that the light-emitting diode in the photocoupler U1 emits light, thereby reducing the resistance value between pins 3 and 4 of the photocoupler U1; the voltage stabilized by the WD1 voltage regulator controls the transistor Q3 to be turned on through pins 3 and 4 of the photocoupler U1 and resistor R13, thereby completing the control of the power-on signal; after the transistor Q3 is turned on, the voltage passes through resistors R3 and R9 to turn on the transistor Q1, thereby outputting a positive voltage control Figure 2The N-type MOS tube on the right side of the middle is saturated and turned on. The processed signal of the sound source must pass through the input operational amplifier, AD analog-to-digital, DSP signal processing, DA digital-to-analog conversion, analog-to-electric output impedance matching and other circuits before it can enter a stable working state and output a normal audio signal. The above-mentioned delayed control signal opens the path of the N-type MOS, and the normal signal source passes normally, realizing normal audio signal output. In summary, this embodiment realizes the startup to avoid various harmonics and switching noises generated during the instability of the electronic circuit, and realizes the startup silencing suppression protection.

[0029] When the power is turned off, the AC power taken from the first AC interface and the second AC interface disappears. Since the filter capacitance of capacitor C1 is set relatively large, a relatively large negative pressure is stored in capacitor C1. The negative pressure stored in capacitor C1 instantly outputs a negative voltage to the step-down circuit composed of diode D3, diode D4 and resistor R1 to control the N-type MOS tube QX to be cut off, cutting off the path of the "power-on and power-off impact sound" at the moment of shutdown, thereby achieving shutdown noise suppression.

[0030] In addition, after the power is turned off, the AC power disappears, and the capacitor C3 and the capacitor C2 are set to have relatively small capacities, so the amount of electricity stored in the capacitors C3 and C2 is also small, and the discharge through the resistors R2, R4, R5, R6, and R7 disappears instantly, the threshold voltage of the voltage stabilizing diode WD1 is turned off, the control voltage through the pins 3 and 4 of the photocoupler U1 and the resistor R13 disappears, the transistor Q3 is turned off, the power-on signal control voltage disappears, the resistors R3 and R9 have no control voltage, so that the transistor Q1 is turned off, thereby turning off the positive voltage control N-type MOS tube voltage. In this embodiment, the path of the "power-on and power-off impact sound" at the moment of shutdown is cut off, and shutdown noise suppression is achieved.

[0031] In summary, the present invention can effectively solve the impact noise of strong signals on the subsequent stage when the equipment is turned on and off or the power is cut off in an emergency by setting a power-on control circuit, a power-on power supply circuit, a power-on delay circuit, a power-on switch tube circuit and a fast power-on and power-off mute circuit, and can realize active noise suppression to achieve a normal listening effect; it can also effectively reduce the damage to the audio circuit and the harm to the human body caused by the impact sound of the audio equipment, avoid the failure of the subsequent equipment, improve the satisfaction of the audience, reduce equipment damage, reduce the number of repairs, and save costs in various links such as after-sales.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An active noise suppression circuit for audio switch, characterized in that: The invention comprises a power-on start control circuit, a power-on start power supply circuit, a power-on start delay circuit, a power-on start switch circuit and a fast power-on / off mute circuit, wherein the power-on start control circuit is connected to the power-on start delay circuit, the power-on start delay circuit is connected to the power-on start power supply circuit, the power-on start power supply circuit is connected to an input end connected to the fast power-on / off mute circuit, the fast power-on / off mute circuit is connected to the power-on start switch circuit at node a, node a is used as a power-on / off control signal output end, node a is connected to an N-type MOS tube; the fast power-on / off mute circuit The input end of the circuit is used to connect to the alternating current; the fast switch silencer circuit includes a diode D1, a diode D2, a diode D3, a diode D4, a capacitor C1 and a resistor R1, the cathode of the diode D1 is connected to the first alternating current interface, the cathode of the diode D2 is connected to the second alternating current interface, the anode of the diode D1 and the anode of the diode D2 are connected to the node b; the cathode of the diode D3 is connected to the node b, the anode of the diode D3 is connected to the cathode of the diode D4; the anode of the diode D4 is connected in series with the resistor R1; one end of the capacitor C1 is connected to the node b, and the other end is grounded.

2. The active noise suppression circuit for audio on / off according to claim 1, characterized in that: The power-on start switch tube circuit includes a resistor R3, a resistor R8, a resistor R9, a diode D8 and a transistor Q1, the cathode of the diode D8 is connected to the DC cathode, the anode of the diode D8 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to a node a; the c pole of the transistor Q1 is connected to the node a, the e pole of the transistor Q1 is connected to the DC positive pole, one end of the resistor R9 is connected to the b pole of the transistor Q1, and the other end of the resistor R9 is connected to the power-on start control circuit; one end of the resistor R3 is connected to the b pole of the transistor Q1, and the other end of the resistor R3 is connected to the DC positive pole.

3. The active noise suppression circuit for audio on / off according to claim 1, characterized in that: The power-on delay circuit includes a resistor R2, a diode D7, a voltage-stabilizing diode WD1 and a capacitor C2, wherein the cathode of the diode D7 is connected to the power-on power supply circuit, the anode of the diode D7 is connected to the cathode of the voltage-stabilizing diode WD1, and the anode of the diode D7 is connected to the power-on control circuit; one end of the resistor R2 is connected to the cathode of the diode D7, and the other end is connected to the anode of the diode D7; one end of the capacitor C2 is connected to the anode of the diode D7, and the other end is grounded.

4. The active noise suppression circuit for audio on / off according to claim 1, characterized in that: The power-on startup power supply circuit includes a diode D5, a diode D6, a resistor R4, a resistor R5, a resistor R6, a resistor R7 and a capacitor C3, wherein the positive electrode of the diode D6 is connected to the first AC interface, the positive electrode of the diode D5 is connected to the second AC interface, and the negative electrode of the diode D6 is connected to the negative electrode of the diode D5; one end of the capacitor C3 is connected to the negative electrode of the diode D6, and the other end is grounded; after the resistors R4, R5, R6 and R7 are connected in parallel respectively, one end is connected to the negative electrode of the diode D6, and the other end is grounded.

5. The active noise suppression circuit for sound on / off according to claim 1, characterized in that: The power-on start control circuit includes transistor Q2, transistor Q3, resistor R10, resistor R11, resistor R12, resistor R13, diode D9, capacitor C4 and photoelectric coupler U1, the c pole of transistor Q3 is connected to the DC positive pole; one end of resistor R10 is connected to the c pole of transistor Q2, and the other end is connected to the b pole of transistor Q2; the positive pole of diode D9 is connected to the b pole of transistor Q2, and the negative pole of diode is connected to the c pole of transistor Q2; one end of capacitor C4 is connected to the b pole of transistor, and the other end is grounded. One end of the resistor R11 is connected to the e-pole of the transistor Q2, and the other end is grounded; the pin (1) of the photoelectric coupler is connected to the e-pole of the transistor Q2, the pin (2) of the photoelectric coupler is connected in series with the resistor R12 and then grounded, the pin (4) of the photoelectric coupler is connected to the power-on delay circuit, and the pin (3) of the photoelectric coupler is connected to the b-pole of the transistor Q3; one end of the resistor R13 is connected to the b-pole of the transistor Q3, and the other end is grounded; the c-pole of the transistor Q3 is connected to the power-on switch circuit, and the e-pole of the transistor Q3 is grounded.

Images