JPH0550197B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a vehicle in which sound is reproduced by a speaker in a living space inside the vehicle, and the volume of the reproduction can be controlled by an electronic volume adjustment means. The present invention relates to a sound device.

(Prior Art) In an automobile, an audio signal from a tuner unit, a cassette tape player, etc. in response to a radio broadcast signal is supplied to a speaker for sound reproduction, and the volume of the sound reproduced from the speaker is adjusted by an electronic volume adjustment means. There is known an audio device that is controlled by. The electronic volume adjustment means in such an audio device usually includes a level adjustment section that changes the level of the audio signal arranged in an audio signal path that supplies the audio signal to the speaker, and a level adjustment section that changes the level of the audio signal there. and a control voltage generation section that supplies a control voltage for controlling the amount of change. The control voltage generation section is provided with, for example, an operation switch for increasing the control voltage level and an operation switch for decreasing the control voltage level, and either of these operation switches is activated by, for example, being pushed. During this time, the control voltage level is continuously increased or decreased, thereby controlling the level adjuster to change the level of the audio signal in response to the change in the control voltage level, so that the level of the audio signal from the speaker is The volume of the resulting reproduced sound can be changed. Therefore, in an audio device using such an electronic volume adjustment means, the volume can be arbitrarily adjusted by simply pressing an operation switch provided in the control voltage generator, for example. There are advantages that can be achieved.

However, even if the power switch for the entire audio device is turned off, the setting state of the control voltage level in the control voltage generator of the electronic volume adjustment means as described above is preserved as it was just before the power switch was turned off. Therefore, when the power switch is turned off and then turned on again to operate the audio equipment, the setting is set to fully open immediately after the power switch is turned on. If the control voltage level set during the previous operation was such that the volume was relatively loud, the power switch is turned on. Additionally, there is a problem in that the speaker suddenly starts emitting sound at a relatively loud volume that the operator did not expect.

Therefore, it is desired that the volume of the audio from the speaker be automatically controlled so as to avoid such inconveniences, but conventional methods for automatic volume control in audio equipment have been disclosed, for example, in Japanese Utility Model Application No. 57-182911. It has been proposed that when the level of an audio signal obtained from a tuner section that receives a radio broadcast signal is below a predetermined level, the audio signal is not supplied to the speaker, as described in . However, nothing has been found that eliminates the inconvenience that may occur immediately after the power switch is turned on in an audio device equipped with the above-mentioned electronic volume adjustment means.

(Object of the Invention) In view of the above, the present invention is configured such that the volume of the reproduced sound obtained from the speakers arranged in the car is adjusted by operating an electronic volume adjustment means, and the power switch is turned on. When the electronic volume adjustment means is activated and the electronic volume adjustment means is operated, the reproduced sound from the speaker is obtained at a volume lower than the volume set by the electronic volume adjustment means until the electronic volume adjustment means is operated anew. It is an object of the present invention to provide a vehicle acoustic device which is configured as follows.

(Structure of the Invention) A vehicle audio device according to the present invention adjusts the volume in accordance with the operation of a control switch in relation to an audio signal path that supplies an audio signal to a speaker disposed inside the vehicle to emit sound. An electronic volume adjustment section and an attenuation circuit section for attenuating the audio signal supplied to the speaker are provided, and the operation of a power switch that supplies operating voltage from a power supply to each part of the audio signal path and the operation of a control switch of the electronic volume adjustment section are provided. A control section is arranged to control the attenuation circuit section in response to It is designed to remain in the operating state until it is operated. With this configuration, when the power switch is turned on and the operating state is assumed, the volume set by the electronic volume adjustment means is reduced at the beginning, so that the operator does not expect it. This prevents the speaker from suddenly starting to emit sound at a relatively high volume, and furthermore, such volume reduction has no effect on subsequent volume adjustment by operating the control switch of the electronic volume adjustment section. It does not cause any hindrance.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

The figure shows an example of a vehicle acoustic device according to the present invention. Terminal 1 is an audio signal input terminal to which an audio signal A obtained from a tuner unit for receiving radio broadcast signals, a cassette tape player, etc. installed in the car is supplied, and from this terminal 1, a preamplifier circuit 2 is supplied. , a level adjustment circuit 3 for changing the level of the audio signal, a resistor R ₁ , and an output amplifying circuit 4 to reach the speaker 5, and an audio signal path is formed for supplying the audio signal A to the speaker 5. These preamplifier circuit 2, level adjustment circuit 3, and output amplification circuit 4 are connected to a power source 6 via a fuse 7, a key switch 8 that enables the operation of each electrical system installed in the automobile, and a power switch 9 for the audio device. The operating voltage V from the power supply 6 is supplied from the voltage supply end of the power supply switch 9.

A control voltage Sv is connected to the voltage supply end of the power switch 9 for controlling the level adjustment circuit 3 to change the level change amount of the audio signal therein.
A control voltage generating circuit 10 that generates the voltage is also connected. This control voltage generation circuit 10 includes two control switches 11 and 12. When the control switch 11 is operated and turned on, the level of the generated control voltage Sv is increased, while the control switch 12 increases the level of the generated control voltage Sv. When it is operated and turned on, the level of the generated control voltage Sv is reduced. Further, the first output terminal of the control voltage generation circuit 10 for sending out the control voltage Sv is connected to the control terminal of the level adjustment circuit 3, and the control voltage Sv is connected to the control terminal of the level adjustment circuit 3.
It is connected to a display section 13 that displays a display according to the level of Sv. Furthermore, the control voltage generation circuit 10
When either of the control switches 11 and 12 is operated and turned on, the control switch signal Sa
It also has a second output end for delivering. and,
Such control voltage generation circuit 10 and level adjustment circuit 3
An electronic volume adjustment section is formed by the above.

The collector of a switching transistor 14 is connected between the resistance R ₁ of the audio signal path and the input end of the output amplifier circuit 4 via a resistance R ₂ , and the emitter of this switching transistor 14 is grounded. . The base of the switching transistor 14 is connected to the output terminal Q of a set/reset flip-flop (S-R flip-flop) circuit 15. This S-R
The set terminal S of the flip-flop circuit 15 is
It is connected to the connection point between voltage dividing resistors R ₃ and R ₄ connected between the voltage supply end of the power switch 9 and the ground point, and its reset terminal R is connected to the control point of the control voltage generation circuit 10. It is connected to the second output from which the switch signal Sa is obtained. Furthermore, S-
A display control circuit 16 for controlling the display mode of the display section 13 is connected to the output terminal Q of the R flip-flop circuit 15, and an output terminal of the display control circuit 16 is connected to a control terminal of the display section 13. There is.

Here, the switching transistor 14 is
When turned on, the audio signal A supplied from the level adjustment circuit 3 to the output amplifier circuit 4 is connected to the resistor R ₁
and resistor R ₂ to divide the voltage and attenuate it,
Resistor _R2 and switching transistor 14 form an attenuation circuit for audio signal A.
Additionally, the switching transistor 14 is S-R.
It is on/off controlled by a control signal Sq obtained at the output terminal of the flip-flop circuit 15, and S-R
The flip-flop circuit 15 includes a voltage dividing resistor _R3 and
Together with _R4 , it forms a control section for the attenuation circuit section.

Based on this configuration, when the power switch 9 is turned on while the key switch 8 is turned on, the preamplifier circuit 2, the level adjustment circuit 3,
The operating voltage V is supplied to the output amplifying circuit 4, the control voltage generating circuit 10, etc., and the entire acoustic device is put into operation. At this time, control voltage generation circuit 1
From 0, the control voltage Sv has a level set in the past operating state of this acoustic device.
is sent out, the level adjustment circuit 3 and the display section 13
The level adjustment circuit 3 adjusts the level of the audio signal A according to the control voltage Sv, and the display unit 13 adjusts the level of the audio signal A according to the control voltage Sv.
The corresponding display will be displayed. At this time, as the power switch 9 is turned on, a voltage V' obtained by dividing the operating voltage V between the voltage dividing resistors R ₃ and R ₄ is obtained, and the S-R flip-flop Since it is supplied to the set terminal S of the circuit 15, S-R
The flip-flop circuit 15 is set at the rise of the voltage V', and the control signal Sq obtained at its output terminal Q assumes a high level. For this reason,
The switching transistor 14 is turned on, and the level-adjusted audio signal A from the level adjustment circuit 3 is divided by the resistors _R1 and _R2 , and the attenuated signal A is obtained between the resistors _R1 and _R2 . Audio signal A is supplied to output amplification circuit 4 . As a result, the volume of the reproduced sound from the speaker 5 is reduced compared to the case where the audio signal A from the level adjustment circuit 3 is supplied to the output amplifier circuit 4 through the resistor R ₁ without being voltage-divided. Even if the control voltage Sv from the control voltage generation circuit 10 is set so that the audio signal A from the level adjustment circuit 3 has a relatively high level, the power switch 9 is in the on state. Accordingly, the loudspeaker 5 does not suddenly start emitting sound at a high volume.

Also, at this time, a high-level control signal Sq from the S-R flip-flop circuit 15 is supplied to the display control circuit 16, and the display control circuit 16 controls the display to blink the display on the display section 13. A signal Sc is generated and supplied to the display section 13. As a result, the display on the display unit 13 becomes blinking,
This indicates that the attenuation circuit formed by the resistor R ₂ and the switching transistor 14 is activated to reduce the volume.

In this state, when either of the control switches 11 and 12 provided in the control voltage generation circuit 10 is operated and turned on, the control switch signal Sa is output from the second output terminal of the control voltage generation circuit 10. The signal is sent out and supplied to the reset terminal R of the S-R flip-flop circuit 15. As a result, S-
It is assumed that the R flip-flop circuit 15 is reset at the leading edge of the control switch signal Sa, and the control signal Sq assumes a low level. Therefore, the switching transistor 14 is turned off, and the level of the audio signal A from the level adjustment circuit 3 is adjusted according to the control voltage Sv from the control voltage generation circuit 10 whose level has been newly set. The voltage is supplied to the output amplifier circuit 4 through the resistor _R1 without being voltage-divided. As a result, the volume of the reproduced sound from the speaker 5 is determined by the control voltage from the control voltage generation circuit 10.
It will be regularly adjusted according to the level of Sv.

Also, at this time, a low level control signal Sq is supplied from the S-R flip-flop circuit 15 to the display control circuit 16.
The display control signal Sc from 6 cannot be obtained. As a result, the display on the display unit 13 does not blink, but instead represents the volume adjustment state based on the level of the control voltage Sv.

Thereafter, each time one of the control switches 11 and 12 provided in the control voltage generation circuit 10 is operated to turn on and the volume is adjusted, the control switch signal Sa resets the S-R flip-flop circuit 15. The control signal Sq is supplied to the terminal R, but this does not change the state of the S-R flip-flop circuit 15 and keeps the control signal Sq at a low level. Therefore, the attenuation circuit section formed by the resistor R ₂ and the switching transistor 14 remains inactive and influences the volume adjustment by the electronic volume adjustment section formed by the level adjustment circuit 3 and the control voltage generation circuit 10. Never.

Note that the attenuation circuit section and the control section therefor in the vehicle acoustic device according to the present invention are not limited to the configurations in the above-mentioned examples, but can take various specific configurations.

(Effects of the Invention) As is clear from the above description, according to the vehicle audio device according to the present invention, during operation, the control switch of the electronic volume adjustment section provided with the control switch can be pressed, for example, by simply pressing the control switch. By adding a simple operation, the volume of the sound played from the speaker can be adjusted arbitrarily, and when the power switch is turned off and turned on to start operation, the power switch is turned on. After the state is set, until the control switch of the electronic volume adjustment section is operated for the first time, the attenuation circuit provided in connection with the audio signal path is activated, and the volume of the sound reproduced from the speaker is reduced. Since the volume is forcibly reduced, it is possible to reliably avoid a situation where the speaker suddenly starts emitting sound at a relatively loud volume that the operator does not expect when the power switch is turned on. be able to. Furthermore, the state in which the volume of the sound played from the speaker is forcibly reduced after the power switch is turned on is automatically canceled when the control switch of the electronic volume adjustment section is operated. The state is shifted to a state where regular volume adjustment is performed by the volume adjustment section, and no inconvenience occurs in the sound reproduction operation.

[Brief explanation of the drawing]

The figure is a circuit connection diagram showing an example of a vehicle audio device according to the present invention. In the figure, 2 is a preamplifier circuit, 3 is a level adjustment circuit, 4 is an output amplifier circuit, 5 is a speaker, 9 is a power switch, 10 is a control voltage generation circuit, 11 and 1
2 is a control switch, 14 is a switching transistor, and 15 is a set/reset flip-flop circuit.

Claims (1)

[Claims] 1. An electronic volume adjustment section that adjusts the volume in accordance with the operation of a control switch, and an attenuation circuit section that attenuates the audio signal, in connection with an audio signal path that supplies audio signals to speakers arranged in the vehicle for sound emission. and a control section that controls the attenuation circuit section in accordance with the operation of a power switch that supplies an operating voltage from a power source to each section of the audio signal path and the operation of a control switch of the electronic volume adjustment section. In a vehicle, the attenuation circuit section is kept in an operating state after the power switch is operated to supply the operating voltage and until the control switch of the electronic volume adjustment section is operated for the first time. sound equipment.