KR920004062Y1 - Malfunction protection circuit for muting circuit - Google Patents

Abstract

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Description

Mute Circuit

Figure is a mute circuit diagram according to the present invention.

* Explanation of symbols for main parts of the drawings

1: Deck micro switch 2: Constant voltage circuit

3: Phase lock loop control circuit 4: First audio output unit

5: 2nd audio output part 6: 1st switching part

7: second switching unit

The present invention relates to a mute circuit, and more particularly, to a mute circuit for preventing a malfunction of a mute circuit by making a constant impulse voltage according to a change in a power supply voltage of a deck micro switch unit.

In general, car audio is configured in either radio or tape mode. If the cassette tape is inserted into the deck mechanism when the user listens to the tape while listening to the radio, then the micro switch of the deck mechanism (hereinafter referred to as deck) is switched. As a result, a power supply voltage is applied to the tape end, and power is supplied to the motor drive in the deck and the operational amplifier OP Amp of the tape end.

At this time, when the micro switch contact of the deck is switched and voltage is applied, a chattering phenomenon occurs, and a peak pulse is generated by a sudden change in voltage and current, resulting in pop noise popping through the speaker. do.

In order to remove the pop noise, a mute circuit using a phase lock loop control circuit is used. However, a mute circuit malfunctions due to a change in power supply voltage.

Accordingly, an object of the present invention is to provide a mute circuit for removing impulsive noise caused by a change in power supply voltage connected to a deck micro switch stage.

In a mute circuit of an audio electronic device of the present invention, a first circuit is connected from a deck micro-switch unit via a constant voltage circuit to turn ON or OFF between the first and second audio output units and ground according to a signal applied thereto. And a second switching unit.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a mute circuit diagram according to the present invention, wherein the deck micro-switch part 1 is connected to the collector terminal of the transistor Q _{1 with} the emitter grounded via R ₁ of the constant voltage circuit _2, and the resistors R ₂ and R Ground via ₃ .

The resistor R ₂ and R ₃ connection points are connected to the base terminal of the transistor Q ₁ via the zener diode D ₁ .

The collector connection point of the resistor R ₁ and the transistor Q ₁ is connected to the resistor R ₆ of the first switching unit 6 via the capacitor C ₁ and the reverse current prevention diode D ₂ .

The capacitor C ₁ and diode D ₂ connection points are grounded via a resistor R ₄ .

On the other hand, the resistor R ₆ of the first switching unit ₆ has an emitter terminal grounded and a collector terminal connected to the first audio output unit 4 and at the base terminal of the transistor Q _{2 which} is grounded through the resistor R ₉ . Connected.

The diode D ₂ and the resistor R ₆ connection point are grounded through the capacitor C ₁ and the resistor R ₈ , respectively, while the collector terminal is connected to the second audio output part 5 via the resistor R ₇ and at the same time the resistor R ₁₀ is connected. Grounded via, the emitter terminal is connected to the base terminal of transistor Q ₃ which is directly grounded.

On the other hand, the diode D ₂ and the resistor R ₆ connection point are connected to the phase lock loop control circuit 3 via the resistor R ₅ and the diode D ₃ . The phase lock loop control circuit 3 is configured to be connected to the deck microphone switch unit 1.

Referring to the operation of the present invention configured as described above are as follows.

When the cassette tape (not shown) is inserted into the deck, the deck micro switch unit 1 is connected to the tape end. At this time, the voltage generated by the shaking phenomenon of the deck micro switch unit 1 is a resistor R ₁ , a capacitor. The capacitor C ₂ is stored for a predetermined time via C ₁ and diode D ₂ and then applied to the respective base terminals of transistors Q ₂ and Q ₃ via resistors R ₆ and R ₇ , respectively.

Thus, the transistors Q ₂ and Q ₃ are turned on so that the first and second audio outputs are grounded so that voice is not output while shaking of the micro switch part occurs.

Before the capacitor C ₂ is completely discharged, a logical " high " signal is output from the phase locking loop control circuit 3 for a predetermined time to perform the same operation as described above.

On the other hand, as the voltage applied to the tape terminal is gradually increased by switching the deck micro switch 1, when the breakdown voltage of the zener diode D ₁ is applied, the diode D ₁ is turned on so that the transistor Q ₁ is turned on. Therefore, the potential at the front end of the capacitor C ₁ is maintained at a constant potential to suppress the generation of an impulse due to the variation of the input voltage.

For example, from 0 to over voltage increases to 10V is the zener diode so the D ₁ breakdown voltage than a state where the transistor Q ₁ has not been powered mute circuit operation, but when 10V or more is the transistor Q ₁ is turned ON to a constant potential The mute circuit does not operate as it is held.

According to the present invention as described above, there is an excellent effect that can prevent the malfunction of the mute circuit generated by the variation of the input voltage applied to the tape end.

Claims (1)

A capacitor C ₁ connected from the deck micro switch unit 1 to allow only an AC component to pass therethrough, a diode D ₁ connected to the capacitor C ₁ to rectify an AC component input thereto, and a signal connected to and input from the diode D ₁ . The first and second switching unit for turning on or off the output of the first and second audio output (4 and 5) to turn on or off the output of the first and second audio output (4 and 5) In the mute circuit also configured 6 and 7, the deck micro switch unit ₁ is connected between the deck micro switch unit 1 and the capacitor C ₁ to maintain a constant voltage variation from the deck micro switch unit 1. The resistors R ₁ and R ₂ connected in parallel from (1), the resistor R ₃ connected between the resistor R ₂ and the ground, the zener diode D ₁ connected from the resistors R ₂ and R ₃ , and the emitter terminal. Is Is not, the base terminal is connected to the Zener diode D ₁ is the collector terminal malfunction prevention circuit of the mute circuit comprises a constant voltage circuit 2 consisting of the transistor Q ₁ is connected to the resistor R _1.