KR0129149B1 - Switch circuit for protecting the speaker - Google Patents

Abstract

This invention relates to a switching circuit for a speaker protection when turning on/off a power-supply. The switching circuit includes: a first diode(D1) for receiving a positive voltage; a first condenser(C1) charged with an output voltage of the first diode(D1); a fourth resistor(R4) for receiving a predetermined positive voltage(V+); a second condenser(C2) charged with an output voltage of the fourth resistor(R4); a comparator(OP) having a non-inverting terminal receiving a voltage charge state of the second condenser(C2), an inverting terminal receiving a voltage charge state of the first condenser(C1), and generating a high signal by comparing the two states therebetween; a relay(RY) for applying an output signal of audio amp to a speaker when receiving the positive voltage(V+); and a switching element(Q) which is turned on/off according to a voltage state from the comparator(OP), and applying an input voltage signal of the relay(RY) to a ground in case of an on-state.

Description

Switching circuit for speaker protection at power on / off

1 is a block diagram of a switching circuit for protecting a speaker according to the present invention.

2 is an operation waveform diagram of the main part.

* Explanation of symbols for main parts of the drawings

R1 to R6: resistors D1 to D3: diodes

C1, C2: Capacitor 10: Comparator

20: relay element Q: NPN transistor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for protecting an audio speaker, and more particularly, to a switching circuit configured to be connected between an output terminal of an audio amplifier and a speaker to protect the speaker when the amplifier is powered on / off.

In general, the DC voltage at the output terminal of the audio amplifier is adjusted to 0V, and the signal transmitted from the audio amplifier to the speaker is limited to the AC signal.

However, when the power is turned on / off, the bias current or voltage changes because the power in the amplifier does not maintain a normal state at that moment.

At this time, the DC voltage of the output terminal of the audio amplifier does not maintain a 0V state, and accordingly, the speaker expresses a thumping sound by a momentary change of the DC voltage.

This phenomenon acts as a major factor to shorten the life of the speaker.

The conventional method for preventing the above factors that shorten the life of the speaker is to manufacture a high-performance amplifier that can prevent the DC voltage from being transmitted from the amplifier to the speaker when the power supply on / off.

Such a method, however, has the disadvantage that the manufacturing cost increases.

The conventional method different from the above is a switching method in which two switches are used, one switch is used as a power switch, and the other switch is used as a speaker switch. If the operating power is kept normal, the speaker switch is turned on to connect the amplifier to the speaker.

If the amplifier is turned off, the speaker switch is turned off and the power switch is turned off.

However, the conventional method using the above-described switch has been presented as a problem of the trouble of operating the switch twice.

In recent years, a speaker protection circuit using a relay element has been developed as a method of eliminating the above inconvenience, but in order to use the relay element, a permanent power source other than the amplifier power source is required. There is a disadvantage that the protection operation is made.

In addition, there is a problem that does not operate when the power supply voltage suddenly changes due to a momentary power failure. An object of the present invention for solving the problems of the prior art as described above is that when the amplifier is powered on by using a comparator and a relay element so that the user does not need any permanent power supply while promoting convenience, the output power of the amplifier is normal. When the status is reached, the speaker is connected, and when the amplifier is turned off, it provides a circuit for protecting the speaker when the power is turned on or off to release the speaker first when the power starts to fall.

A feature of the present invention for achieving the above object is a switching device for protecting an audio picker from an overvoltage generated when the audio amplifier is powered on / off, a predetermined positive voltage (V +) generated when the amplifier is powered on. ) Is a first resistor (R1) receiving the input, the first diode (D1) to the output of the first resistor (R1), and the first capacitor (C1) charged by the output voltage of the diode (D1). And a second capacitor C2 charged by a fourth resistor R4 receiving the output of the first resistor R1 and a voltage output from the fourth resistor R4, and the second capacitor C2. When the voltage charging state of the input terminal is input to the non-inverting input terminal and the voltage charging state of the first capacitor C1 is input to the inverting input terminal, the magnitude of the voltage input to the non-inverting input terminal becomes larger than the voltage input to the inverting input terminal. Comparator 10 for outputting a high signal only, and On according to the state of the voltage output from the relay element 20 and the comparator 10 which receives a predetermined positive voltage (V +) and connects the signal generated from the amplifier to the speaker when the current is applied and cuts off the current It includes a switching element (Q) that is turned on / off and conducts a current to the relay element 20 by conducting a voltage signal input to the relay element 20 to the ground during the on operation.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a configuration diagram of a switching circuit for protecting a speaker according to the present invention, the first resistor (R1) receiving a predetermined positive voltage (V +) generated when the power-on operation of the amplifier, and the output signal of the first resistor (R1) The first diode (D1) receiving the input, the third resistor (R3) for conducting the output signal of the first diode (D1) to ground, and the first charged by the voltage applied to the third resistor (R3) A capacitor C1, a second resistor R2 for conducting the output signal of the first resistor R1 to ground, a fourth resistor R1 for receiving the output signal of the first resistor R1, and the The second resistor (C2) charged by the voltage output from the fourth resistor (R4), and the fourth resistor (R4) in order to provide a fast discharge path at the time of discharge of the voltage charged in the second capacitor (C2). A second diode D2 having an input terminal connected to an output terminal of the output terminal and an output terminal connected to an input terminal of the second resistor R2, and the second cone. The voltage charging state of the capacitor C2 is input to the non-inverting input terminal, the voltage charging state of the first capacitor C1 is input to the inverting input terminal, and the magnitude of the voltage input to the non-inverting input terminal is the magnitude of the voltage input to the inverting input terminal. Only when larger, the comparator 10 for outputting a high signal, the fifth resistor (R5) for receiving the predetermined positive voltage (V +), the fifth resistor (R5) and the output terminal of the comparator 10 And a sixth resistor (R6) for receiving an output signal, the relay element 20 and the sixth resistor for receiving a predetermined positive voltage (V +) to connect the signal generated from the amplifier to the speaker when the current is applied NPN transistor Q which is turned on / off according to the state of the voltage output from R6 and conducts current to the relay element 20 by conducting a voltage signal input to the relay element 20 to ground during the on operation. It is composed of

In addition, an output terminal is connected to an input terminal of the relay element 20 to prevent current from being conducted to the relay element 20 by a counter electromotive current caused by a voltage across the collector terminal of the NPON transistor Q. A third diode D3 having an input terminal connected to the collet terminal of the transistor Q is configured.

In addition, the capacitance of the first capacitor C1 and the second capacitor C2, and the third and fourth resistance values, the charging time of the first capacitor through the first diode charges the second capacitor through the fourth resistor. It may be designed so that the discharge time of the first capacitor through the third resistor is slower than the discharge time of the second capacitor through the second diode.

An example of the preferred operation of the present invention according to the configuration of FIG. 1 is as follows.

In order to operate the relay device 20 only when the power supply voltage is in a normal state, the transistor Q may be turned ON only under the power supply voltage in the normal state. It consists of a comparator 10, first and second diodes D1 and D2, first and second capacitors C1 and C2 and several resistors.

First, when the power switch is turned on and the power supply voltage rises from 0 V, the output of the comparator 10 is caused by increasing the voltage of the inverting terminal 2 of the comparator 10 before the voltage of the non-inverting terminal 3. The voltage of the terminal 4 may be kept low. The voltage of the inverting terminal 2 of the comparator 10 is charged through the first resistor R1 and the first diode D1 at the voltage across the first capacitor C1, and the non-inverting terminal of the comparator 10 ( The voltage of 3) is formed through the first resistor R1 and the fourth resistor R4.

Accordingly, if the charging time of the first capacitor C1 is faster than the charging time of the second capacitor C2 by appropriately selecting the resistance and the capacitor value, the comparator 10 is inverted during the time when the power supply voltage reaches a steady state. The voltage at the terminal 2 is higher than the voltage at the non-inverting terminal 3. As a result, the voltage at the output terminal 4 of the comparator 10 is low, and the relay element 20 is in an off state. Is maintained. When the power supply voltage reaches a steady state, the voltage of the non-inverting terminal 3 becomes equal to the voltage of the terminal 1, but the voltage of the terminal 2 is connected to the first resistor R1 through the first diode D1. Lower than the voltage of the terminal 3 by the voltage drop, the terminal 4 is high, and the relay element 20 is kept on.

On the other hand, when the power is off and the voltage drops from V +, the relay element 20 must be hopped first, so the voltage of the output terminal 4 of the comparator 10 should be transitioned to the low state. To be in this state, the voltage of the inverting terminal 2 of the comparator 10 must be discharged late and the voltage of the non-inverting terminal 3 must be discharged quickly. The voltage of the inverting terminal 2 of the comparator 10, that is, the voltage of the first capacitor C1 is discharged through the third resistor R3, and the voltage of the non-inverting terminal 3 is the second diode D2 ( It is separated from R4, but mainly through D2) and discharged through the second resistor R2, so that the third resistor R3, the first capacitor C1, the second resistor R2, and the second capacitor C2 are discharged. If the value is appropriately set, that is, if the discharge time of the first capacitor C1 is slower than the discharge time of the second capacitor C2, the voltage of the inverting terminal 2 is made higher than that of the non-inverting terminal 3. (In the normal state, the positive voltage of the terminal 2 is lower than the voltage of the terminal 3 by the amount of the voltage drop of the first diode D1.) As a result, the voltage of the terminal 4 is made low to bring the relay element 20 to a low state. Can be turned off. When the power supply voltage reaches 0V, since the transistor Q0 is off, the relay element 20 is also kept off.

Thus, in the present invention, since the relay element 20 is connected by connecting the output of the amplifier and the speaker, the relay element 20 remains off when the power supply switch is turned on and the power supply voltage of the amplifier rises from 0v to V +. If it is kept constant at V +, the signal is turned on. When the power switch is turned off and the voltage drops from V + to 0V, the relay element 20 is first turned off when the power voltage starts to fall from V +. Accordingly, the output of the amplifier is connected to the speaker only when the power supply voltage is V +, and the speaker can be protected from transient voltages that can be applied instantaneously by disconnecting the speaker from the amplifier at the time of power on or off. In addition, it is possible to prevent annoying sounds that may occur when the power is turned on or off.

In addition, it will be described in detail with reference to Figure 2 attached to the preferred operation example of the speaker protection switching circuit according to the present invention having a hole as described above.

2 is an operation waveform diagram of a main part, (a) is an illustration of the main operation waveform of each part in the power-on operation, and (b) is a diagram of the main operation waveform of each part in the power-off operation.

When the power supply of the amplifier is turned on, the predetermined positive voltage V + rises (see FIG. 2 (a)). As a result, the voltage dropped and output from the first resistor R1 increases at a similar rate. (a) in Figure 1).

The voltage output from the first resistor R1 is input to the first diode D1 and the second and fourth resistors R2 and R4, and the voltage input to the first diode D1 is greater than or equal to a predetermined voltage. When raised, the first diode D1 is driven to apply an input voltage to the third resistor R3.

At this time, the first capacitor C1 is charged by the voltage conducted to the ground through the third resistor R3, and the charging voltage state of the first capacitor C1 is indicated by reference numeral 2 in FIG. As shown in

In addition, the output voltage of the first resistor R1 applied to the second and fourth resistors R2 and R4 is conducted to the ground through the second resistor 2 and thereby the second resistor R2. The voltage having the same magnitude as that applied to the second voltage is dropped again by the fourth resistor R4 to charge the second capacitor C2.

The charging voltage state of the second capacitor C2 is as shown at 3 in FIG. 29 (a).

The voltage signals charged in the first capacitor C1 and the second capacitor C2 are input to the data input terminal of the comparator 10, and the comparator 10 is connected to the non-inverting input terminal of the second capacitor C2. When the first capacitor C1 having the charging voltage input to the inverting input terminal is less than the charging voltage, a low signal is output, and in contrast, a high signal is output.

The output signal of the comparator 10 is as shown at 4 in FIG. 2 (a). When the output signal of the comparator 10 is in the low state, the output terminal of the comparator 10 performs the same function as the ground, so that the predetermined positive voltage V + is all lowered through the fifth resistor R5. Lose. Therefore, the signal input to the base terminal of the NPN transistor Q through the sixth resistor R6 is in the low state, and thus the NPN transistor Q is in the off state.

When the NPN transistor Q is in the opposition state, the relay element 10 that receives the predetermined positive voltage V + is not electrically connected.

Subsequently, when the output signal of the comparator 10 changes as shown by reference numeral '4' in FIG. 2 (a), the NPN transistor Q is turned on when the output signal changes from the low state to the high state. The voltage is switched to the state and the voltage input to the relay element 20 is conducted to the heater terminal through the collector terminal of the NPN transistor (Q).

Therefore, the voltage state applied to the collector terminal of the NPN transistor Q is as shown by reference numeral '5' in FIG. 2 (a).

The relay element 20 operates according to the ON operation of the NPN transistor Q, and is transferred to the signal gas picker generated from the amplifier.

The speaker protection circuit according to the present invention operates when the amplifier power is supplied in the above process.

Unlike the above-described amplifier power supply, when the amplifier power is cut off, the general operation is performed in the reverse process of the above-described process, which will be briefly described with reference to the attached second (b).

When the power of the amplifier is cut off, the predetermined positive voltage V + drops (see V + in FIG. 2 (b)), and accordingly, the voltage dropped by the first resistor R1 drops and outputs at a similar rate (second voltage). (b) the reference numeral '1'.

Accordingly, the charges charged in the first and second capacitors C1 and C2 are discharged. The first capacitor C1 is discharged through the third resistor R3, but the second capacitor C2 is discharged. ) Is discharged through the second diode D2, and despite the difference in charging capacity, the second capacitor C2 discharges relatively quickly compared to the first capacitor C1 (reference numeral '(b) of FIG. 2 (b)). 2 ',' 3 ').

The voltage signal discharged to the first capacitor C1 and the second capacitor C2 is compared by the comparator 10 and the voltage input from the second capacitor C2 is the voltage input from the first capacitor C1. When smaller, the state is changed from the high state to the low state (see reference numeral '4' in FIG. 2 (b)).

Therefore, the signal input to the base terminal of the NPN transistors Q through the sixth resistor R6 is switched from the low state to the high state, and the NPN transistor Q is turned off.

The moment the NPN transistor Q is turned off, the relay element 20 is not energized (see reference numeral 5 in Fig. 2 (b)).

In response to the off operation of the NPN transistor Q, the relay element 20 is turned off to block a signal transmitted from the amplifier to the speaker.

When the amplifier is powered on by using a comparator and a relay element to provide a switching circuit for protecting a speaker during power on / off according to the present invention operating as described above, which does not require any permanent power while promoting user convenience. When the output power reaches to the normal state, connect the speaker and turn off the power of the amplifier, that is, if the output power of the amplifier falls, there is an effect of removing the speaker before the power down.

Claims (2)

A switching device for protecting an audio speaker from an overvoltage generated when powering on / off an audio amplifier, the switching device comprising: a first resistor (R1) receiving a predetermined positive voltage (V +) generated when the power supply of the amplifier is turned on; A first diode D1 having an output of the first resistor R1 as an input; A first capacitor c1 charged by the output voltage of the first diode D1; A fourth resistor R4 receiving the output of the first resistor FR1; A second capacitor C2 charged by the voltage output from the fourth resistor R4; The voltage charging state of the second capacitor C2 is input to the non-inverting input terminal, the voltage charging state of the first capacitor C1 is input to the inverting input terminal, and the magnitude of the voltage input to the non-inverting input terminal is input to the inverting input terminal. A comparator 10 for outputting a high signal only when the voltage is greater than the magnitude of the voltage; A relay element (20) which receives the predetermined positive voltage (V +) and connects a signal generated from the amplifier to a speaker when the current is applied and cuts off the current; And a switching to turn on / off according to the state of the voltage output from the comparator 10 and to conduct a current to the relay element 20 by conducting a voltage signal input to the relay element 20 to ground during the on operation. Switch circuit for protecting the speaker when the power supply on / off, characterized in that it comprises an element (Q). The third resistor (R3) of claim 1, wherein the third resistor (R3) is connected between the output terminal of the first diode (D1) and the ground to provide a discharge path when the voltage charged in the first capacitor (C1) is discharged. and; A second resistor (R2) for conducting the output of the first resistor (R1) to ground; And an input terminal connected to an output terminal of the fourth resistor R4 and an output terminal connected to an input terminal of the second resistor R2 to provide a fast discharge path when the voltage charged in the second capacitor C2 is discharged. A fifth resistor R5 connected to the output of the comparator 10 by receiving the second diode D2 and the predetermined positive voltage V + configured to be connected; And a sixth resistor (r6) for receiving the output of the comparator (10) and connecting it to the input of the switch element (Q).