JPH1155781A - Automatic sound volume switching circuit for audio system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the sound volume of an audio system without being restricted or prevented by a lead line by switching the sound volume of the audio system with a signal from a portable telephone set. SOLUTION: An automatic sound volume switching circuit is composed of a receiver 11 to which an antenna 10 is fitted and a relay circuit 12 which is electrically connected to the receiver 11. In the relay circuit 12, an output (a) from the amplifier DC.MP of the receiver 11 flows to the relay circuit 12 and the contact point B/B' of the relay is switched from a contact point C/C' to D/D'. In a tuner 2 where the contact point B/B' is opened, signals to the speakers SP(L) and SP(R) are interrupted and sound does not come out from the speakers SP(L) and SP(R) from which sound is outputted till then. When the user of the portable telephone set terminates, the signals to the receiver 11 are interrupted and the contact point B/B' of the relay is returned to the contact point C/C' and sound is emitted from the speakers SP(L) and SP(R).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic sound volume switching circuit that can switch the volume of an audio system including a main body of audio equipment such as a tuner and a tape player and a speaker by a signal from a portable telephone.

[0002]

2. Description of the Related Art When a mobile phone is used in a running automobile, it is desirable to temporarily reduce or cut off the volume of an audio system such as a car radio. One of the means for this is to electrically connect a mobile phone and a muting circuit of the audio device body.

[0003]

In the prior art, the range in which a portable telephone can be used in a vehicle may be limited by the length of a lead wire connecting the portable telephone and the main body of the audio equipment. Also, even if the length is not restricted, the fact that the lead wire extends long in the car,
Often this hinders the free movement of the passenger.

Accordingly, an object of the present invention is to provide a volume switching circuit capable of reducing the volume of an audio system without being restricted or hindered by such lead wires.

[0005]

In order to solve the above problems, the present invention is based on the premise that the volume of an audio system including an audio device main body and a speaker is automatically switched by a signal from a mobile phone. The present invention is characterized by a volume switching circuit capable of
The circuit, a receiver provided with an antenna for receiving a high-frequency signal from the mobile phone, and connected to the receiver, interposed between the audio device body and a speaker, the receiver And a relay capable of turning on / off a connection state between the audio device main body and the speaker depending on the presence or absence of a signal from the audio device.

In one preferred embodiment of the present invention, a muting mechanism operable when the audio device main body and the speaker are turned off by the operation of the relay is interposed between the audio device main body and the speaker. I have. In another embodiment, the receiver may receive an audio signal from the mobile phone and operate the relay by the signal.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of an automatic volume switching circuit of an audio system according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an example of an on-vehicle audio system using an automatic volume switching circuit. This system includes a tuner 2 and a pair of speakers SP (L) and S (S).
P (R). The figure also shows a mobile phone 3 used in combination with this system.

This switching circuit comprises a receiver 11 to which an antenna 10 is attached, and a relay circuit 12 electrically connected to the receiver 11. The relay circuit 12 includes a tuner 2 and a speaker SP (L),
It is interposed between SP (R) and shown by dashed lines in the figure.

FIG. 2 shows the details of the receiver 11 and the antenna 10. The receiver 11 transmits a high-frequency signal A from the mobile phone 3 to the high-frequency amplifier RF. AMP, and converts it into a DC signal by the detection circuit of the diode D1. AMP
The relay circuit 12 is operated only while the mobile phone 3 is used.

In the relay circuit 12 (see FIG. 1), the amplifier DC. The output a from the AMP flows to the relay circuit 12, and the contact B / B 'of the relay is changed to the contact C /
Switch from C 'to D / D'. The tuner 2 with the contacts B / B 'opened has the signal to the speakers SP (L) and SP (R) cut off, and the speaker SP from which sound has been output until then.
No sound is output from (L) and SP (R). Mobile phone 3
When the use of the relay is finished, the signal to the receiver 11 is cut off, and the contact B / B 'of the relay returns to the contact C / C' to return to FIG.
And the sound is output again from the speakers SP (L) and SP (R).

As shown in FIG. 1, the relay circuit 12 includes a muting mechanism including a switch SW2 and resistors R and R '. When the contact B / B 'of the relay is opened by the signal A of the mobile phone 3, the speaker SP
To prevent any sound from being output from (L) and SP (R), this switch SW2 is opened as shown.
However, while using the mobile phone 3, the speakers SP (L),
When it is desired that a sound that does not disturb the use of the telephone 3 is produced, instead of producing no sound from the SP (R), the switch SW2 is closed and the speaker SP ( L) and SP (R) can be sounded. The volume at that time can be adjusted by the values of the resistors R and R '.

FIG. 3 is a drawing similar to FIG. 2 showing an example of the configuration of the receiver 11. The receiver 11 has a plug P that can connect to the mobile phone 3 and receive the audio signal A ′. The audio signal A ′ is output from the audio amplifier AF. A
MP, and is rectified by a diode D2 to become a DC signal. After being amplified by the AMP, a direct current a ′ flows through the relay circuit 12 and acts similarly to the direct current a.

As described above, the volume automatic switching circuit in the illustrated example operates with either the high-frequency signal A or the audio signal A 'from the portable telephone 3 by selectively using the switches SW1 and SW1' (see FIGS. 2 and 3). When the high frequency signal A is used, the volume of the tuner 2 can be reduced before the bell of the mobile phone 3 rings, so that the sound of the bell is missed. There is an advantage that there is no. The automatic volume switching circuit according to the present invention can be implemented in a mode using only the high frequency signal A.

[0015]

The automatic volume switching circuit of the audio system according to the present invention can receive a high frequency signal from a mobile phone and switch the volume, so that a lead wire for connecting the audio system to the mobile phone is unnecessary. Thus, it is possible to eliminate restrictions and the like that would occur when using such lead wires. According to this circuit, the volume of the audio system can be reduced before the bell of the telephone rings, so that the sound of the bell is not missed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an audio system including an automatic volume switching circuit.

FIG. 2 is a circuit diagram of a receiver.

FIG. 3 is a drawing similar to FIG. 2, illustrating an embodiment of a receiver.

[Explanation of symbols]

 2 Audio equipment body (tuner) 3 Mobile phone 10 Antenna 11 Receiver 12 Relay circuit SP (L), SP (R) Speaker

Claims (3)

[Claims] 1. A volume switching circuit capable of automatically switching a volume of an audio system including an audio device main body and a speaker by a signal from a mobile phone, wherein the circuit includes a high-frequency signal from the mobile phone. A receiver provided with an antenna for receiving the audio device main body and a speaker connected to the receiver and interposed between the audio device main body and the speaker, and the presence or absence of a signal from the receiver. The above circuit comprising a relay capable of turning on / off a connection state with a speaker. 2. The circuit according to claim 1, wherein a muting mechanism operable when the audio device main body and the speaker are in an off state by the operation of the relay is interposed between the audio device main body and the speaker. 3. The circuit according to claim 1, wherein the receiver is capable of receiving an audio signal from the mobile phone and operating the relay by the signal.