JPH0511692U - Speaker switching circuit - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a speaker switching circuit capable of efficiently and reliably switching between an external speaker and an internal speaker using a 2-pin jack. In a circuit for switching between an external speaker 1 and an internal speaker 2 using a 2-pin type jack, one terminal portion of a jack receiving portion 3-2 is grounded and the other terminal portion and an audio amplifier portion 4 are connected. A circuit 10 for applying a predetermined bias voltage via a bias resistor is connected to the connecting portion 9 connected to the internal speaker 2, and the internal speaker 2 is connected to the connecting portion 9 via an appropriate switch circuit 13 and further connected. A speaker switching circuit configured to include a voltage detection circuit 14 that detects the potential of the unit 9 and to control the switch circuit 13 according to the output of the voltage detection circuit 14.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a speaker switching circuit.

[0002]

[Prior Art]

 Conventionally, in an audio system in which an external speaker and an internal speaker can be used, either the external speaker or the internal speaker is selectively used according to the environment in which the audio system is used, and music or radio is selectively used. It is becoming common to listen to broadcasts, etc.

However, the switching method between the external speaker and the internal speaker in such an audio system normally uses a 3-pin type jack 3 as shown in FIG. One terminal portion 6 of the receiving portion 3-1 of the jack 3 is connected to, for example, an output portion of an audio system, for example, an amplifier (AMP), the terminal portion 7 is connected to the internal speaker 2, and further another terminal. The structure is such that the part 8 is grounded.

On the other hand, when the insertion portion 3-2 of the jack portion 3 connected to the external speaker is inserted into the receiving portion 3-1 of the jack 3, the switching piece P 1 connected to the terminal portion 6 is The connection 5 is displaced so that the connection 5 between the switching piece P and the inner end of the terminal portion 7 connected to the internal speaker 2 is opened, and the external speaker is driven.

[0005] By the way, such a 3-pin type jack 3 is not a general one, and there is a problem such as an increase in cost. If a pin type insertion jack is used instead, it is impossible to block the drive of the internal speaker, so there is a problem that both the external speaker and the internal speaker are driven at the same time.

[0006]

[Problems to be solved by the device]

 An object of the present invention is to solve the problems in the related art and to provide a speaker switching circuit that can switch between an external speaker and an internal speaker efficiently and reliably by using a 2-pin jack. is there.

[0007]

[Means for Solving the Problems]

 The present invention adopts the following technical configurations in order to achieve the above object. That is, in a circuit for switching between an external speaker and an internal speaker using a 2-pin type jack, one terminal of the jack receiving section is grounded and the other terminal is connected to the audio amplifier section. A voltage detection circuit that connects a circuit that applies a predetermined bias voltage via a bias resistor to the connection part, connects an internal speaker to the connection part through an appropriate switch circuit, and further detects the potential of the connection part. The speaker switching circuit is provided with a circuit and is configured so that the switch circuit is controlled according to the output of the voltage detection circuit.

[0008]

[Action]

 Since the present invention adopts the above-described technical configuration, when the jack of the external speaker is inserted, the fact that the bias voltage is applied decreases the voltage of the terminal portion of the jack receiving portion to which the bias voltage is applied. The switch circuit for controlling the drive of the internal speaker is cut off based on the detection of the voltage drop, so that the drive of the internal speaker is surely stopped.

[0009]

【Example】

 Hereinafter, a specific example of the speaker switching circuit according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a specific example of a speaker switching circuit according to the present invention. In a circuit for switching an external speaker 1 and an internal speaker 2 by using a 2-pin type jack 3, a jack receiving section is provided. 3-1 One terminal portion 8 is grounded, and a predetermined bias voltage is applied to the connection portion 9 to which the other terminal portion 6 and the audio output portion (amplifier portion) 4 are connected, via the bias resistor R. In addition to connecting the circuit 10, a voltage detection circuit 14 for connecting the internal speaker 2 to the connection portion 9 through an appropriate switch circuit 13 and further detecting the potential of the connection portion 9 is provided. The speaker switching circuit is configured so that the switch circuit 13 is controlled according to the output of the speaker switching circuit.

In the present invention, a capacitor 11 for cutting an appropriate DC component may be provided between the audio output unit 4 such as the amplifier and the connection unit 9. Further, the bias voltage in the present invention is not particularly limited, but in the case of an on-vehicle audio device, it is preferably 12 V, and in other cases, it is preferably 5 to 8 V, for example.

Further, the voltage detection circuit 14 used in the present invention is not particularly limited in its configuration, but detects the potential of the connection portion 9 and detects a predetermined threshold value. In comparison, when the potential is lower than the threshold value, it is preferable to incorporate a comparison circuit including an appropriate comparator or the like that can output an output signal.

Although the structure of the switch circuit 13 for controlling the drive of the internal speaker 2 is not particularly limited, it can be turned ON / OFF electronically according to the ON / OFF signal of the voltage detection circuit 14. Any switching circuit can be used as long as it has such a built-in mechanism.

The operation of the speaker switching circuit according to the present invention will be described. Now, considering the case where only the internal speaker is driven without using the external speaker 1, the connection is made by the bias voltage applied from the bias circuit 10. Since the voltage of the section 9 maintains a predetermined high voltage, the voltage detection circuit 14 for detecting the potential of the connection section 9 outputs an ON signal, that is, an "H" level signal. Therefore, the switching circuit 13 is turned on according to the "H" level signal, so that the audio output is transmitted to the internal speaker and the internal speaker is driven.

When the external speaker 1 is used, when the insertion block stage 3-2 of the 2-pin type jack is inserted into the receiving portion 3-1 of the 2-pin type jack, the external speaker 1 is used. Since the internal coil of is connected to the resistance R of the bias circuit, if the value of the resistance R is made sufficiently large, the electric potential of the connection portion 9 is lowered by the current flowing through the external speaker.

By setting the potential drop of the connection portion 9 due to the voltage drop to be lower than the threshold value of the voltage detection circuit 14, when the external speaker is connected, the voltage detection circuit is connected. An OFF signal, that is, an "L" level signal is output from 14, and the switching circuit 13 is turned OFF based on this, so that the audio output is not transmitted to the internal speaker, and only the external speaker can be driven. become.

[0016]

[Effect of the device]

 In the present invention, since it is configured as described above, it is not necessary to use an uncommon 3-pin type jack, but to use a 2-pin type jack that has been generally used in large quantities in the past. Not only can the external speaker be switched to the internal speaker reliably and efficiently, but it also has commonality in connection with other devices, which is convenient.

[0017]

[Brief description of drawings]

FIG. 1 is a block diagram showing a specific example of a speaker switching circuit according to the present invention.

FIG. 2 is a block diagram showing an example of a conventional speaker switching circuit.

[Explanation of symbols]

 1 ... External speaker 2 ... Internal speaker 3 ... Jack part 3-1 ... Jack receiving part 3-2 ... Jack insertion part 4 ... Audio output part 6, 7, 8 ... Terminal part 9 ... Connection part 10 ... Bias circuit part 13 ... Switch circuit 14 ... Voltage detection circuit

Claims (1)

[Claims for utility model registration] 1. In a circuit for switching between an external speaker and an internal speaker using a 2-pin type jack, one terminal of the jack receiving portion is grounded and the other terminal is connected. A circuit for applying a predetermined bias voltage via a bias resistor is connected to the connection section connected to the audio amplifier section, an internal speaker is connected to the connection section via an appropriate switch circuit, and the connection section is further connected. The speaker switching circuit is characterized in that a voltage detection circuit for detecting the potential of is provided, and the switch circuit is controlled according to the output of the voltage detection circuit.