JPH0418760B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a vehicle-mounted speaker system equipped with a volume balance control circuit that controls the audio signal level supplied to a plurality of front and rear speakers installed in a vehicle interior.

Conventional technology and problems In car speaker systems, the front
A four-speaker system is commonly used, with two front speakers placed on either side of the instrument panel or the left and right doors, and two rear speakers placed on both sides of the rear deck.
Such speaker systems generally include a volume balance control circuit (hereinafter referred to as a control circuit) that can adjust the volume balance between the front speakers and the rear speakers.
FIG. 3 is a block diagram showing a conventional control circuit, in which left channel and right channel audio signals are input from a tuner, cassette deck, etc. (not shown) to input terminals Lin and Rin, respectively.
The left channel signal is input to both input ends of the variable resistor 21 via resistors R and R. Variable resistor 21
The output is inputted to the front left speaker 24 and the rear left speaker 28 via power amplifiers 23 and 27, and drives both speakers. The right channel signal is input to both input terminals of the variable resistor 22 via resistors R and R, and is further input to the front right speaker 26 and rear right speaker 30 via power amplifiers 25 and 29 to drive each speaker. .
The variable resistors 21 and 22 are configured in an interlocked manner, and a control circuit is configured by these two variable resistors. Adjustment of the volume balance between the front and rear speakers is performed using the sliding terminals 21' of the variable resistors 21 and 22.
Performed at 22'. For example, when the sliding terminals 21', 22' are slid toward the side indicated by arrow A in the figure, the outputs of the rear speakers 28, 30 are emphasized, and the outputs of the front speakers 24, 26 are attenuated. If it is slid to the side indicated by B in the figure, the opposite will occur.

By the way, there are many cars that have a relatively large amount of space for the rear deck, so a relatively large diameter (for example,
It is possible to install a speaker unit of 16 to 20 cm), and the trunk room can be used as a back cavity for the speaker.
As shown in the figure, it is very advantageous for reproduction of low frequency range.
It can play up to quite a low range. However, due to space constraints, front speakers can only be installed with speaker units with a small diameter (about 10 cm at most), and the buffer effect is often insufficient. cannot be played.

Under these conditions, conventional control circuits change the volume balance between speaker systems with different low-frequency reproduction characteristics as described above, resulting in changes not only in the sound field balance but also in the frequency balance of the reproduced sound. Ta. Sometimes, when the control circuit was tilted toward the front speakers, which had poorer low-frequency reproduction characteristics (attenuating the rear speaker output), the resulting sound was significantly lacking in bass.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned conventional drawbacks, and its object is to provide a system that eliminates changes in low-frequency reproduced sound due to the position of the sliding terminal of the volume balance control circuit.

Structure of the Invention According to the present invention, the above-mentioned object is to provide a pair of speakers with poor low-frequency reproduction characteristics provided on the front left and right sides of the vehicle interior, and a pair of speakers with excellent low-frequency reproduction characteristics provided on the rear left and right sides of the vehicle interior, respectively. and,
An in-vehicle speaker system comprising a volume balance control circuit that interlocks and controls the levels of audio signals output from the front speaker pair and the rear speaker pair,
A low frequency component extraction means for passing only the low frequency range of the audio signal, and a level adjustment means for adjusting the level of the output of the low frequency component extraction means and supplying it to the rear speaker pair, and the volume balance control. The level adjusting means is linked with the volume balance control circuit so that the level attenuation characteristic for the rear speaker pair in the circuit is opposite to the level attenuation characteristic for the output of the low frequency component extracting means in the level adjusting means. This is achieved by the constructed in-vehicle speaker system.

Embodiments of the Invention Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. Audio signals from audio equipment such as a tuner, cassette deck, etc. (not shown) are input to input terminals Lin and Rin. Lin is the input terminal for the left channel signal, and Rin is the input terminal for the right channel signal. The left channel signal input to the input terminal Lin is input to one input terminal of the variable resistors 1 and 9, and is also input to the mixing circuit 15. The output of the variable resistor 1 is input from a sliding terminal 1' to a front left speaker 4 via a high-pass filter 2 and a power amplifier 3 to drive the speaker 4. The output of the variable resistor 9 is input from the sliding terminal 9' to the rear left speaker 11 via the power amplifier 10 and drives the speaker 11. Also input terminal
The right channel signal input to Rin is the variable resistor 5
and 12 are inputted to one input terminal, and also inputted to the mixing circuit 15. The output of the variable resistor 5 is input from the sliding terminal 5' to the front right speaker 8 via the high pass filter 6 and the power amplifier 7, and drives the speaker 8. The output of the variable resistor 12 is input from the sliding terminal 12' to the rear right speaker 14 via the power amplifier 13 and drives the speaker 14. The mixing circuit 15 mixes the left and right channel signals, and the output signal is sent to the other inputs of the variable resistors 9 and 12, which are level adjustment means, via a low-pass filter 16, which is a low-frequency component extraction means, and a buffer circuit 17, which is used to adjust impedance. entered at the end. Here, the cutoff frequency of the low-pass filter 16 is in the low frequency range where there is little sense of direction in the auditory sense, that is, 100.
It is configured to only pass low frequencies below ~150Hz. The high-pass filters 2 and 6 are configured to pass the frequency band that is not passed by the low-pass filter 16.

The variable resistors 1, 5, 9, and 12 are interlocked, and these variable resistors constitute a volume balance control circuit.
also serves as a level adjustment means. Furthermore, the front speaker pair 4 and 8 have poor low frequency reproduction characteristics as shown in Figure 2b, and the rear speaker pair 8 and 14 have excellent low frequency reproduction characteristics as shown in Figure 2a. .

The operation of this embodiment will be explained below.

The output levels of variable resistor pairs 1 and 5 and variable resistor pairs 9 and 12 are inversely proportional to each other. That is, the sliding terminals 1', 5', 9', 12' are connected to the variable resistors 1, 12',
When located at an intermediate point between 5, 9, and 12 (the state shown in the figure), each speaker 4, 8, 11, and 14 outputs and reproduces at the same volume. At this time, high-frequency sounds are mainly output and reproduced from the front speakers 4 and 8 by the high-pass filters 2 and 6, and the rear speakers 11 and 14
From here, the entire range sound will be output and played back. When the sliding terminals 1', 5', 9', and 12' are slid in the direction shown by C in the figure, the audio signals of the left and right channels are attenuated in the variable resistors 1 and 5, so that the audio signals from the front speakers 4 and 8 are attenuated. The volume of the output reproduction is reduced, and the output reproduction sound over the entire band from the rear speakers 11 and 14 is emphasized. At this time, the output signal of the buffer circuit 17 is attenuated by the variable resistors 9 and 12 and is not output and reproduced from the speakers 11 and 14. Therefore, the sliding terminals 1', 5', 9', 1
When 2' is completely narrowed down in the direction of arrow C, the reproduced sound from the front speakers 4 and 8 disappears, and only the reproduced sound in the entire band from the rear speakers 11 and 14 is output. Next, when sliding terminals 1', 5', 9', and 12' are slid in the direction shown by arrow D, high-frequency sounds are output and reproduced from front speakers 4 and 8, while variable resistors 9 and 12 The left channel signal and right channel signal respectively input to one input terminal are attenuated by the resistor and are not output and reproduced from the rear speakers 11 and 14. However, the low frequency signal that is the output of the buffer circuit 17, that is, the high pass filters 2 and 6
The low-frequency signal with little sense of direction that is cut off at
The output is reproduced from 1 and 14. Therefore, when the sliding terminals 1', 5', 9', and 12' are fully compressed in the direction of arrow D, only the high-frequency sound defined by the high-pass filters 2 and 6 is output from the front speakers 4 and 8.
Since the rear speakers 11 and 14 output only the low frequency range defined by the low-pass filter 16, the overall sound is output in the same way as when each slider is tightened in the direction of arrow C, resulting in frequency balance. No more deformation occurs. At this time, the low-frequency sound output from the rear speakers 11 and 14 has no sense of direction, so the listener does not feel that it is being output from the rear speakers 11 and 14, which impairs the function of the control circuit. Never. still,
In the above embodiment, the left and right channel signals are mixed and output and reproduced, but even if the signal is a stereo signal, there is little audible sense of direction in the low frequency range of 100 to 150 Hz, so the signal is mixed and then reproduced. However, the stereo effect will not be affected. In that case, a stereo feeling can be obtained by separating the mid- and high-frequency ranges. Furthermore, although it is not necessary to provide the high-pass filters 2 and 6, by providing them so that the low-frequency reproduced sound is output only from speakers with excellent low-frequency reproduction characteristics, the low-frequency reproduction sound due to the difference in low-frequency reproduction characteristics can be output. In addition, since low-frequency signals that cause small speakers with poor low-frequency reproduction characteristics to produce unreasonably large amplitudes are not input, cross-modulation distortion in the speaker system can be prevented.
Furthermore, since the bandwidth of the power amplifier system that drives the small speaker system is limited, cross-modulation distortion can be prevented and the dynamic range can be widened.

Effects of the Invention As described above in detail, according to the present invention,
When the volume balance control circuit is adjusted to the front speaker side, the front speaker pair mainly outputs high-frequency sounds, and the rear speaker pair outputs only low-frequency sounds with little sense of direction, and the volume also increases. When the balance control circuit is adjusted to the rear speaker side, the whole range sound is output from the rear speaker pair, so there is no adverse effect on the original volume balance control circuit function, and the volume balance control circuit is It is possible to always obtain rich low-frequency reproduction sound by eliminating variations in low-frequency reproduction sound due to the position of the sliding terminal.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the in-vehicle speaker system of the present invention, FIG. 2 is a frequency characteristic diagram of the speaker, and FIG. 3 is a block diagram showing a conventional in-vehicle speaker system. In the figure, 1, 5, 9, 12 are variable resistors, 2, 6 are high pass filters, 3, 7, 10, 13 are power amplifiers, 4, 8, 11, 14 are speakers, 15 is a mixing circuit, 16 is a low pass Filter 17 is a buffer circuit.

Claims (1)

[Claims] 1 A pair of speakers with poor low-frequency reproduction characteristics installed on the front left and right sides of the vehicle interior, a pair of speakers with excellent low-frequency reproduction characteristics installed on the rear left and right sides of the vehicle interior, and a pair of speakers on the front side and the rear side speakers. A vehicle speaker system comprising: a volume balance control circuit that controls the levels of audio signals output from a pair of speakers in conjunction with each other; Level adjustment means is provided to adjust the level of the output of the frequency component extraction means and supply it to the rear speaker pair, and the level attenuation characteristic for the rear speaker pair in the volume balance control circuit is adjusted to the level attenuation characteristic of the rear speaker pair in the volume balance control circuit. An in-vehicle speaker system characterized in that the level adjustment means is configured in conjunction with the volume balance control circuit so that the level attenuation characteristic for the output of the low frequency component extraction means is opposite to that of the output.