JPS61117999A - Audio device mounted on automobile - Google Patents

Abstract

PURPOSE:To share a sound electric power amplifier circuit by providing an inner sound attenuating means for attenuating an inner sounc outputed from a radio tuner part/cassette reproducting part and a signal path for introducingan outer sound signal supplied to an outer cound input terminal to an amplifier. CONSTITUTION:When a warning voice signal is supplied to the outer input terminal 2b of a car audio part 2, it supplies said signal to the inversion input terminal 13c of an arithmetic amplifier 13 through a coupling capacitor 24 and a resistance 25, and simultaneously supplies said signal to the base of a transistor 27 through a resistance 26. A DC voltage is supplied to the arithmetic amplifier 13 and a sound electric power amplifier circuit 14 through the collector of a transistor 9. When the cassette reproducing part 11 is in the off-state, only the warning voice signal introduced to the arithmetic amplifier 13 is amplified to be outputted in a sound from a speaker 23. When the cassette reproducing part 11 outputs an audio signal, it is voltage-divided by resistances 16 and 32, and the attenuated audio signal is supplied to the inversion input terminal 13c of the arithmetic amplifier 13.

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to an in-vehicle audio device such as a car audio system, a car radio, or a car stereo, and particularly has an external audio input terminal. This in-vehicle audio device attenuates the internal sound output by a radio tuner part/cassette playback part when an external audio signal is supplied, and mixes the internal sound and external sound to output the mixed sound from a speaker.

(Prior art and its problems) Due to advances in voice synthesis technology, cars are now equipped with systems that give audio warnings, so-called voice warning systems. As shown in FIG. 3, this voice warning system consists of a car radio/car stereo section 51, a relay 50, a voice warning section 53, and a speaker 52.
By connecting the common contact 50a and the first contact 50b, the audio signal output from the car radio/car stereo section 51 is outputted as a sound from the speaker 52, and in this state, the voice warning section 53 outputs a warning voice. When the signal is generated, the voice warning section 53 excites the coil 54 of the relay 50 to connect the common contact 50a and the second contact 50C of the relay 50, and outputs the warning voice signal from the subiichiro 52. let

However, in such a system, the output of the car radio/car stereo section 51 and the output of the voice warning section 53 are directly output from the speaker 52, so the car radio/car stereo section 51 and the voice warning section 51 are directly output from the speaker 52. It is necessary to provide an audio power amplification circuit in both the awning section 53 and the awning section 53. Also, when the warning voice is output from the speaker 52, the car radio/car stereo section 51
Because the output was cut, I was unable to hear the warning voice while listening to music.

(Object of the Invention) In view of the above-mentioned circumstances, when a car radio or a car stereo is operating and outputting an audio signal, and the voice warning unit outputs a warning voice, the audio signal is At the same time, the attenuated audio signal and the warning voice signal can be mixed and output from the speaker, and the warning voice signal and the audio signal can be amplified using one audio power amplification circuit. The objective is to provide an in-vehicle audio device that allows parts to be shared.

(Structure and Effects of the Invention) To achieve this object, the in-vehicle audio II according to the present invention amplifies internal audio signals output from a radio tuner section/cassette playback section in an amplifier section and outputs audio from a speaker. *Internal audio attenuation that attenuates the internal audio output from the radio tuner section/cassette playback section when an external audio signal is supplied to the external audio input terminal provided in the car audio section. and a signal path for guiding an external audio signal supplied to the external audio input terminal to the amplifying section. With this configuration, in the present invention, (a) the audio power amplification circuit can be shared, and the audio signal output from the car radio etc. and the warning voice signal output from the voice warning section can be switched; You can eliminate the need for glue,
This allows for total cost reduction.

(b) Furthermore, when an audio system such as a car radio is operating, the audio output from the audio system can be moderately reduced to mainly output the warning voice.

(Description of an Embodiment) FIG. 1 is a circuit diagram showing an embodiment of an in-vehicle audio device according to the present invention. The car audio device shown in this figure is composed of a voice warning section 1, a car audio section 2, and a power supply 3. The DC voltage output from the power supply 3 is connected to the power input of the voice warning section 1. The power is supplied to the terminal 1a and the power input terminal 2a of the car audio section 2.

The voice warning section 1 receives a predetermined value, for example +5V, from the DC voltage applied to the 'ri source input terminal 1a.

It is equipped with a power supply circuit 4 that generates stable DC voltages such as +15V and -15V, and the stabilized DC voltage generated here is supplied to the power supply terminal 5a of the warning circuit 5 and the power supply terminal 6a of the voice synthesis circuit 6. Each is supplied. The warning circuit 5 is turned on by the stabilized DC voltage, detects brake abnormalities, engine abnormalities, overspeeding, etc. of the vehicle and outputs them in the form of a code.
This encoded code is supplied to the input terminal 6b of the speech synthesis circuit. The speech synthesis circuit 6 stores speech information corresponding to each code in advance using a PARCOR (partial autocorrelation) method, an LPG (linear predictive coding) method, a SP (line spectrum analysis) method, etc. When a code is supplied from the warning circuit 5, a warning voice signal (external audio signal) corresponding to this code is output.
That is, as shown in FIG. 2, a signal consisting of the DC component vh and the AC component is synthesized and supplied to the external audio input terminal 2b of the car audio section 2.

When the car audio unit 2 receives a DC voltage applied to its power input terminal 2a, it supplies this DC voltage to the terminal 7a of the audio switch 7 and also to the emitter of the transistor 9 via the diode 8. When someone turns on the audio switch 7, the terminal 7a
The DC voltage applied to terminal 7b and diode 10
is supplied to the power terminal 11a of the radio tuner section/cassette playback section 11 via the terminal 7b and the diode 12 to the positive 1! of the operational amplifier 13. The power supply terminal 13a and the positive power supply terminal 14a of the audio power amplification circuit 14 are supplied with the power supply terminal 13a. The radio tuner section/cassette playback section 11 converts the DC voltage applied to its positive power supply terminal 11a into a capacitor 15.
This DC voltage is used to turn on the radio when the driver presses the tuner selection button (as shown), and turns on the cassette when the driver presses the cassette selection button (as shown) to output the audio signal. The audio signal (internal audio signal) obtained here is transmitted through a resistor 16, a coupling capacitor 17,
The signal is supplied to the inverting input terminal 13c of the operational amplifier 13 via the resistor 18 in sequence. In the 8Il\S amplifier 13, the negative power supply terminal 13b is grounded, and a negative feedback resistor 19 is inserted in parallel between the output terminal 13e and the inverting input terminal 13C, and the positive power supply terminal 13a and the ground point are roughly connected. Bias resistors 20 and 21 are connected in series between the two resistors 20 and 21, and the connection point P of these resistors 20 and 21 is connected to the non-inverting input terminal 13d, and the audio signal is supplied to the inverting input terminal 13C. If so, this audio signal is amplified, a DC component determined by the resistor 20.degree. The audio power amplification circuit 14 has its negative power supply terminal 14b grounded, and when an audio signal is supplied to the input terminal 14C, it amplifies the power and outputs audio from the speaker 23.

In other words, in this car audio section 2, when the driver turns on the audio switch 7, the radio tuner section
The cassette playback unit 11 generates an audio signal, which is guided to the operational amplifier 1$13, amplified by the operational amplifier 13 and the audio power amplification circuit 14, and output as audio from the speaker 23.

Further, when the warning voice signal is supplied to the external input terminal 2b of the car audio section 2, the signal is supplied to the inverting input terminal 13G of the operational amplifier 13 via the coupling capacitor 24 and the resistor 25 in sequence. At the same time, the warning voice signal is supplied to the base of the transistor 27 via the resistor 26. The base of the transistor 27 is grounded via a resistor 28, the emitter is grounded, and the collector is connected via a resistor 29 to the emitter of the transistor 9 (this emitter is connected to the capacitor 3).
(grounded through diode 3, and DC voltage is applied through diode 8), it is turned on by the DC component vh of this warning voice signal, reducing its collector potential to almost zero. do. As a result, the base potential of the transistor 9 decreases through the resistor 30, turning it on, and when a warning voice signal is supplied to the base of the transistor 27, the operational amplifier 13 and the audio power are supplied through the collector of the transistor 9. DC voltage is supplied to the amplifier circuit 14. Therefore, when the radio tuner section/cassette playback section 11 is off, only the warning voice signal guided to the operational amplifier 13 by the signal path 31 consisting of the capacitor 24° and the resistor 25 is amplified and output as sound from the speaker 23. . Furthermore, when the collector potential of the transistor 27 becomes almost zero, the resistor 32 connected to the collector of the transistor 27
One end of the is almost grounded.

Therefore, at this time, if the audio switch 7 is turned on and the radio tuner section/cassette playback section 11 is outputting an audio signal, this audio signal is divided by the W1 resistors 16 and 32, and the attenuated audio signal is calculated. It is supplied to the inverting input terminal 13c of the amplifier B13.

In other words, in this case, the warning voice signal is outputted from the speaker 23 with the same magnitude, and only the audio signal is attenuated and outputted from the speaker 23.

Further, in the embodiment described above, the warning voice signal outputted by the voice warning section 1 is input to the car audio section 2, but other voice signals, for example, the voice signal outputted by the car radio customer, are input to the car audio section 2. It is also possible to input the signal to the external audio input terminal 2b of the section 2.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of an in-vehicle audio device according to the present invention, FIG. 2 is a diagram showing an example of the waveform of a warning voice signal used in this embodiment, and FIG. 3 is a diagram showing a conventional voice warning signal. FIG. 1 is a block diagram showing an example of a system. DESCRIPTION OF SYMBOLS 1... Voice warning part, 2... Car audio part, 2b... External audio input terminal, 11... Radio tuner part/cassette playback part, 13... Amplification part (operational amplifier), 14 ...Amplification section (audio power amplification circuit), 1
6.32...Internal sound attenuation means (resistance), 23...
Speaker, 27... Internal sound attenuation means (transistor), 31... Signal path.

Claims (1)

[Claims] An in-vehicle audio device that amplifies an internal audio signal output from a radio tuner section/cassette playback section in an amplifier section and outputs audio from a speaker, and the external audio signal is input to an external audio input terminal provided in the car audio section. internal audio attenuating means for attenuating the internal audio output from the radio tuner section/cassette playback section when the external audio signal is supplied to the external audio input terminal; and a signal path for guiding the external audio signal supplied to the external audio input terminal to the amplifying section. An in-vehicle audio device characterized by comprising: