JPH0713356Y2 - Front and rear volume balance adjustment device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a front and rear volume balance adjusting device in a stereo sound reproduction system in which speakers are arranged in front of and behind a listening position.

BACKGROUND ART Some vehicle-mounted stereo sound reproduction systems are provided with front and rear speakers for left and right channels, respectively, and there is a front and rear volume balance adjusting device for adjusting the balance of the volume output from the front and rear speakers.

FIG. 2 shows a conventional example of a front-rear volume balance adjusting device. In this device, a front output terminal L _OUTF is connected via a resistor 11 to a left channel audio signal input terminal L _IN , and a rear output terminal L _OUTR is connected via a resistor 12. A volume 13 for adjusting the front-rear volume balance is provided between the output terminals L _OUTF and L _OUTR , and a mover of the volume 13 is grounded. The right channel also has the same configuration as the left channel, with the input terminals R _IN , output terminals R _OUTF , R
Resistors 14 and 15 and a volume 16 are provided at the input terminal R _IN between _OUTR . Volumes 13 and 16 are designed to work together.

In such a configuration, the supplied left channel audio signal level is e _L , the resistance values of the resistors 11 and 12 are r, and the resistance value of the output terminal L _OUTF side of the mover of the volume 13 is
R _1, and the resistance value of the backward output terminal L _OUTR side of the movable element and R _2, the front output _{R 1 e L / (r +} R 1) , and the rear output
It becomes R ₂ e _L / (r + R ₂ ). This also applies to the right channel. That is, since R ₁ + R ₂ = constant, the front and rear output ratios are determined according to the positions of the movers of the volume controls 13,16.

In such a conventional front-rear volume balance adjusting device, after the front-rear volume balance is adjusted by the variable resistance values 13 and 16, the front-rear output ratio becomes constant regardless of the level of the supplied audio signal level. However, particularly in a reproduction environment with large ambient noise, such as an in-vehicle stereo sound reproduction system, for example, when the volume balance is adjusted so that the front output is larger than the rear output, at a high audio signal level, FIG. As shown in (a), it suffices if the front output and the rear output are larger than the ambient noise. However, as shown in Fig. 3 (b), the front output is rear output due to the ambient noise when the audio signal level is small. However, there was a problem that it was masked and could not be heard. This is also the case when the volume balance is adjusted so that the rear output is higher than the front output, and the front output becomes inaudible due to ambient noise.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a front-rear volume balance adjusting device capable of listening to front and rear outputs without being disturbed by ambient noise even in the case of a small audio signal.

The front-rear volume balance adjusting device of the present invention is a front-rear volume balance adjusting device which is provided for each channel in an audio reproduction system and adjusts the volume balance between the front output and the rear output according to a balance adjustment command. An input terminal, a front output terminal and a rear output terminal, a main volume adjusting variable resistor for adjusting the level of the audio signal supplied to the input terminal, an audio signal output of the main volume adjusting variable resistor, and a front output terminal, A fixed resistor provided between the rear output terminal and one of the rear output terminals, and an output correction variable provided between the audio signal output of the main volume adjusting variable resistor and the other of the front output terminal and the rear output terminal. Obtain the intermediate output of the resistor and the two fixed terminals and the resistor between the two fixed terminals while changing the intermediate output according to the balance adjustment command. For each channel, a front and rear volume balance adjusting variable resistor having a moving element, one of the two fixed terminals is connected to the front output terminal, the other is connected to the rear output terminal, and the mover is grounded. It is characterized in that the resistance value of the output correction variable resistor is changed in association with the change of the attenuation rate for the audio signal by the main volume adjusting variable resistor.

Embodiment An embodiment of the present invention will be described below with reference to FIG.

In the front and rear volume balance adjusting apparatus according to an embodiment of the present invention shown in FIG. 1, the same parts as those of the conventional apparatus shown in FIG. A rear output correction volume (variable resistor for output correction) 23 is provided in addition to a control volume (variable resistor for adjusting front and rear volume balance) 13.
The volume 23 is provided between the rear output terminal L _OUTR and the input side of the resistor 11, and its mover is connected to the rear output terminal L _OUTR . In the connection line between the volume 23 and the resistor 11, the output of the main volume control volume (main volume control variable resistor) 21 of the left channel of the volume playback system,
That is, an audio signal is supplied from the mover of the volume 21 via the buffer amplifier 22. The mover of the rear output correction volume 23 is interlocked with the mover of the volume adjusting volume 21, and the position of the mover can be arbitrarily changed by a knob, a lever or the like. Also in the right channel, resistance 14, volume 16 for adjusting the front and rear volume balance,
The main volume adjusting volume 24, the buffer amplifier 25, and the rear output correction volume 26 are provided in the same structure as the left channel, and the movable element of the rear output correction volume 26 is interlocked with the movable element of the volume adjustment volume 24 to arbitrarily The positions of those movers can be changed.

In such a configuration, the audio signal of the left channel is attenuated by the volume adjusting volume 21 at an attenuation rate according to the position of the mover, and is supplied to the resistor 11 and the rear output correcting volume 23 via the buffer amplifier 22. Here, the resistance value r of the resistors 11, R ₁ the resistance value of the forward output terminal L _OUTF side of the movable element of the volume 13, the resistance value of the backward output terminal L _OUTR side of the movable element when the R _2, the front output The first attenuation rate is R ₁ / (r + R ₁ ) as in the conventional case.
On the other hand, since the resistance value between the fixed terminals of the rear output correction volume 23 changes according to the attenuation rate of the volume adjusting volume 21, it can be expressed as a function r (1) α when the attenuation rate of the volume 21 is α. Therefore, the second attenuation rate of the rear output is R ₂ / (r (α) + R ₂ ).

That is, the first attenuation rate of the front output is constant unless the front-rear volume balance adjusting volume 13 is operated, but when the mover of the volume adjusting volume 21 is moved in the direction of arrow A, the attenuation rate α increases. Become. Since the mover of the rear output correction volume 23 moves in the direction of arrow B in conjunction with this, the resistance value r (α) decreases, and the second attenuation factor of the rear output decreases due to the decrease in the resistance value r (α). Become. Therefore, by operating the volume control volume 21, the buffer amplifier 22
The lower the output level of, the higher the rear output level becomes than the front output level. When the mover of the volume adjusting volume 21 is moved in the direction opposite to the arrow A, the attenuation rate α decreases. In conjunction with this, the mover of the rear output correction volume 23 moves in the direction opposite to the arrow B, so that the resistance value r (α) increases, and the second attenuation factor of the rear output increases the resistance value r (α). Grows larger. Therefore, if the output level of the buffer amplifier 22 rises by operating the volume adjusting volume 21, the rear output level becomes relatively smaller than the front output level. This also applies to the right channel.

In the above-described embodiment of the present invention, two mechanical variable resistors are used as the volume, and the operating portion of the volume serves as the command means. However, when the electronic volume is used, the command switch circuit commands. It becomes a means.

Further, in the above-described embodiment of the present invention, the second attenuation factor of the rear output is changed according to the position of the mover of the volume adjusting volume 21, but it is assumed that the front output is masked. In this case, the first attenuation rate of the front output may be changed according to the position of the mover of the volume adjusting volume 21.

Effects of the Invention As described above, in the front-rear volume balance adjusting device of the present invention, a fixed resistor is provided at one of the audio signal output of the main volume adjusting variable resistor and the front output terminal or the rear output terminal. Between the front output terminal and the rear output terminal, a variable resistor for adjusting the front and rear volume balance is provided between the front output terminal and the rear output terminal. The position of the mover is changed, and the front and rear volume balance can be balanced as in the conventional device. Also, since the resistance value of the output correction variable resistor changes in conjunction with the change in the attenuation rate for the audio signal by the main volume adjustment variable resistor,
When the attenuation rate for the audio signal by the main volume adjusting variable resistor becomes large, the resistance value of the output correcting variable resistor can be changed to forcibly change the volume balance of the rear output and the front output. . Therefore, even if the volume is lowered by the main volume adjustment, the relative volume balance of the rear output and the front output is changed, and it is possible to prevent one of the rear output and the front output from being masked by ambient noise such as running noise. It is. For example, when the front output level is higher than the rear output level as shown in FIG. 3 (a), even if the volume is reduced by the main volume adjustment, the rear output level decreases less than the front output level reduction rate. It is possible to prevent the masking state due to the ambient noise of the rear output as shown in FIG. 3 (b) from occurring.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a conventional front and rear volume balance adjusting device, and FIG. 3 is a diagram showing a masking state by noise. Explanation of symbols for main parts 13,16… Volume control for front and rear volume balance 21,24… Volume for volume control 23, 26… Rear output correction volume

Claims (1)

[Scope of utility model registration request] 1. A front-rear volume balance adjusting device, which is provided for each channel in a sound reproduction system and adjusts a volume balance between a front output and a rear output according to a balance adjustment command, comprising an audio signal input terminal and a front output. Terminal and rear output terminal, main volume adjusting variable resistor for adjusting the level of the audio signal supplied to the input terminal, audio signal output of the main volume adjusting variable resistor, the front output terminal and the rear A fixed resistance provided between the output terminal and one of the output terminals, and an output correction provided between the audio signal output of the main volume adjusting variable resistor and the other of the front output terminal and the rear output terminal. And a variable resistor for the two terminals and an intermediate output of the two fixed terminals and the resistor between the two fixed terminals are changed according to the balance adjustment command. A variable resistor for adjusting the front-rear volume balance in which the movable element has a movable element and one of the two fixed terminals is connected to the front output terminal, the other is connected to the rear output terminal, and the movable element is grounded. Before and after each channel, and the resistance value of the output correction variable resistor is changed in association with the change of the attenuation rate of the audio signal by the main volume adjusting variable resistor. Volume balance control device.