JP2001148900A - Stereo reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain excellent three-dimensional stereo reproduction with less number of components. SOLUTION: A noninverting amplifier 14L applies noninverting-amplification to a sound signal of a left channel of a stereo signal, an inverting amplifier 14R applies inverting-amplification to a sound signal of a right channel to drive a medium high frequency reproduction speaker 12L whose positive pole terminal is connected to an output terminal of the noninverting amplifier 14L via a low frequency interruption capacitor CL, a medium high frequency reproduction speaker 12R whose negative pole terminal is connected to an output terminal of the inverting amplifier 14R via a low frequency interruption capacitor CR, and a woofer 13 connected in series with a medium and high frequency block inductor I that is connected between the output terminal of the noninverting amplifier 14L and the output terminal of the inverting amplifier 14R.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereo reproducing apparatus in which a non-inverting amplifier and an inverting amplifier are operated in all bands to enable efficient 3D stereo reproduction.

[0002] A conventional stereo reproducing apparatus 1 shown in FIG.
A pair of middle and high frequency reproduction speakers 2L and 2R corresponding to the left and right channels and a low frequency reproduction speaker 3 corresponding to a monaural channel obtained by synthesizing the left and right channels are provided to reproduce stereo sound by a 3D method. The middle and high frequency components of the left channel audio signal are supplied to the non-inverting amplifier 5L via the low frequency cutoff filter 4L, and the (Re + Rf) / Re
It is amplified with a certain gain, and supplied from the output terminal of the non-inverting amplifier 5L to the positive terminal of the left-channel middle and high frequency reproduction speaker 2L. On the other hand, the middle and high frequency components of the right channel audio signal are supplied to the non-inverting amplifier 5R via the low-frequency cutoff filter 4R, amplified with a gain of (Re + Rf) / Re, and output from the output terminal of the non-inverting amplifier 5R. It is supplied to the negative electrode terminal of the right channel middle and high frequency reproduction speaker 2R. In the case of this example, the negative terminal of the left channel middle and high frequency reproduction speaker 2L and the positive terminal of the right channel middle and high frequency reproduction speaker 2R are commonly grounded.

Further, the left channel audio signal and the right channel audio signal are mixed in a mixer 6, and the synthesized left / right channel audio signal obtained here is supplied to a middle / high frequency cutoff filter 7, where only low frequency components are removed. Is extracted. The extracted low frequency component is supplied to the positive terminal of the low frequency reproduction speaker 3 via the non-inverting amplifier 8. An inverting amplifier 9 is connected to the non-inverting amplifier 8 via a ground resistor Re.
The output of the inverting amplifier 9 is supplied to the negative terminal of the low frequency reproduction speaker 3. Since the non-inverting input terminal of the inverting amplifier 9 is grounded and the inverting input terminal and the output terminal are connected by the feedback resistor rf, the inverting input of the non-inverting amplifier 8 with a gain of -rf / Re, that is, the non-inverting input thereof. The low frequency component of the synthesized left and right channel audio signal is amplified. As a result, the low-frequency reproduction speaker 3 applies a BTL (Ba) that applies signals having almost the same amplitude and opposite phases to the positive terminal and the negative terminal.
lanced Transformer-Less) circuit, SE
Low-frequency enhanced reproduction is performed with an output that is four times that of the PP (Single Ended Push-Pull) circuit driving method.

[0004]

In the conventional stereo reproducing apparatus 1, the non-inverting amplifier 8 and the inverting amplifier 9 for low-frequency reproduction are provided in addition to the pair of non-inverting amplifiers 5L and 5R provided for mid-high frequency reproduction. It is necessary, and furthermore, in order to obtain low-frequency components necessary for low-frequency monaural reproduction, a mixer 6 for mixing and synthesizing a left-channel audio signal and a right-channel audio signal is required. However, the production cost is high. Also, various filters such as the low-frequency cutoff filters 4L and 4R and the middle-high frequency cutoff filter 7 are obstacles to the reduction of the manufacturing cost. In addition, as for the non-inverting amplifiers 5L and 5R, the cutoff frequency of the preceding low-frequency cutoff filter 4L is reduced. The amplification function in the following band is not used,
The stereo reproducing apparatus 1 uses the non-inverting amplifiers 5L, 5R, 8 and the inverting amplifier 9 in such a manner that the amplifying function in the band equal to or higher than the cutoff frequency of the preceding middle- and high-frequency cutoff filter 7 is not used. There is a problem that the amplifier function provided in the amplifier 9 is not fully utilized.

Also, without using any speaker driving amplifier such as the non-inverting amplifiers 5L, 5R, 8 and the inverting amplifier 9, for example, a mid-high range reproducing speaker and a low-frequency reproducing speaker are provided via a passive type channel divider including an inductor and a capacitor. It is clear that even if a two-way stereo playback device or the like that drives a speaker is configured, it is not possible to variably adjust the low-range and mid-high range audio reproduction levels, and the low-range and mid-high range audio reproduction levels can be freely adjusted. The stereo reproduction device 1 that can be variably adjusted has a future value that should be sufficiently evaluated as long as the cost / performance ratio is improved.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to enable good 3D stereo reproduction with a small number of components.

[0007]

In order to achieve the above object, the present invention provides a non-inverting amplifier for non-inverting amplifying an audio signal of one channel of a stereo signal and an audio signal of the other channel of the stereo signal. An inverting amplifier for inverting and amplifying, a first mid-high range reproducing speaker having a positive terminal connected to an output terminal of the non-inverting amplifier via a low-frequency cutoff unit, and a low-frequency cutoff unit at an output terminal of the inverting amplifier. A second mid-high frequency reproduction speaker having a negative terminal connected thereto, and a low frequency reproduction speaker connected in series with mid-high frequency cutoff means between an output terminal of the non-inverting amplifier and an output terminal of the inverting amplifier. And a speaker.

Further, the present invention is characterized in that the low-frequency cutoff means is a capacitor, and the middle and high-frequency cutoff means is an inductor.

[0009]

An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a circuit diagram showing one embodiment of the stereo reproduction apparatus of the present invention.

A stereo reproduction apparatus 11 shown in FIG. 1 reproduces left and right channel signals of a stereo signal with a pair of right and left middle and high frequency reproduction speakers 12L and 12R in the middle and high frequency bands, and lowers the combined left and right channel signals in a low frequency band. Region reproduction speaker 13
The 3D method of reproducing the audio signal by using the non-inverting amplifier 14L and the inverting amplifier 14R provided for each of the left and right channels is required only as the speaker driving amplifier.
Accordingly, although the total number of speakers is 3 as in the related art, the total number of speaker drive amplifiers is 2, and a configuration is employed in which the manufacturing cost of the entire apparatus is thoroughly reduced along with the reduction of the band limiting filter and the like.

As described above, one of the channels (here, the left channel) is constituted by the non-inverting amplifier 14L and the other channel (here, the right channel) is constituted by the inverting amplifier 14R as the speaker driving amplifier. Attention should be paid to the polarity when connecting to the region reproduction speakers 12L and 12R. That is, the non-inverting amplifier 14
L and the inverting amplifier 14R, respectively, via the low-frequency cutoff capacitor CL.
L and 12R are connected to speaker terminals with opposite polarities in order to match the phases of the sound outputs of both channels. Specifically, the left channel mid-high range reproduction speaker 12L has a positive terminal connected to the output terminal of the non-inverting amplifier 14L via a capacitor CL, and the right channel mid-high range reproduction speaker 12R has an output terminal of the inverting amplifier 14R. Is connected to a negative terminal via a capacitor CL. The negative terminal of the left channel mid-high range reproduction speaker 12L and the positive terminal of the right channel mid-high range reproduction speaker 12R are commonly grounded. Re and Rf are the ground resistance and feedback resistance of the non-inverting amplifier 14L, respectively, and r
i and rf are an input resistance and a feedback resistance of the inverting amplifier 14R, respectively.

Further, as described above, the stereo reproducing apparatus 11 employs the 3D method of synthesizing the left and right channels and reproducing the low frequency monaural sound. Therefore, the low frequency reproducing speaker 13 outputs the synthesized output signal of the left and right channels. Is driven by the low-frequency component included in the. Here, the non-inverting amplifier 1
The 4L output terminal is connected to the positive terminal of the low-frequency reproduction speaker 13 via the middle-high frequency cutoff inductor I, while the negative terminal is connected to the output terminal of the inverting amplifier 14R. Since the positive electrode terminal and the negative electrode terminal of the speaker 13 are connected to each other by a voice coil, the mid-high frequency cutoff function of the middle high frequency cutoff inductor I and the non-inverting amplifier 14L supplied to the low frequency reproduction speaker 13 are inverted. It will contribute equally to the output of amplifier 14R.

When the speakers 12L, 12R and 13 have, for example, a crossover frequency of 150 Hz and a voice coil impedance of 16Ω, the middle and high frequency cutoff capacitors CL and CR of 66 μF are used. It is preferable to use a blocking inductor I of 33 mH. Also, the speakers 12L, 1
As 2R, 13, for example, the crossover frequency is 500
When a voice coil impedance of 16 Ω at Hz is used, it is preferable to use a capacitor of 20 μF for the middle and high frequency cutoff capacitors CL and CR and a capacitor of 10 mH for the low frequency cutoff inductor I.

The operation of the stereo reproducing apparatus 11 having the above configuration is as follows. First, the non-inverting amplifier 14L non-inverts and amplifies all the band components of the left channel audio signal. In the amplified left channel audio signal, the mid-high frequency component passed through the low frequency cut-off capacitor CL is supplied to the mid-high frequency reproduction speaker 12L, and the low frequency component passed through the mid-high frequency cut-off inductor I is low. It is supplied to the area reproduction speaker 13. Similarly, the entire band component of the right channel audio signal is inverted and amplified by the inverting amplifier 14R. Of the right channel audio signal amplified here,
The mid-high frequency component that has passed through the low-frequency cut-off capacitor CR is supplied to the mid-high frequency reproduction speaker 12R, and the low-frequency component that passes through the mid-high frequency cut-off inductor I is low-frequency reproduction speaker 1R.
3 is supplied. For this reason, the audio signals of the left and right channels amplified by the non-inverting amplifier 14L and the inverting amplifier 14R are divided into a middle and high frequency component and a synthesized low frequency component for each channel, and are efficiently supplied to speaker driving.

As described above, according to the speaker reproducing device 11, the left channel audio signal of the stereo signal is non-inverted and amplified by the non-inverting amplifier 14L, and the right channel audio signal is inverted and amplified by the inverting amplifier 14R. A low-frequency cutoff capacitor C is connected to the output terminal of the amplifier 14L.
A mid-high range reproduction speaker 12L having a positive terminal connected via L, a mid-high range reproduction speaker 12R having a negative terminal connected to an output terminal of the inverting amplifier 14R via a low range cut-off capacitor CL, and a non-inverting speaker. Since the low frequency reproduction speaker 13 connected in series with the middle and high frequency cutoff inductor I between the output terminal of the amplifier 14L and the output terminal of the inverting amplifier 14R is driven, the non-inverting amplifier 14L and the inverting amplifier 14R A total of three amplifiers can be used to drive the middle and high frequency reproduction speakers 12L and 12R of each channel and the low frequency reproduction speaker 13 common to both channels. In addition, since the non-inverting amplifier 14L and the inverting amplifier 14R both amplify the audio signals of the left and right channels in the entire band, unlike the conventional amplifier in which only a part of the band is amplified, the amplification function of the amplifier is maximized. It can be used effectively. Also, since the audio signals of the left and right channels are reproduced by the 3D method, which focuses on the point that the sense of direction of the stereo in the low frequency range is less than that in the middle and high frequency ranges, pseudo stereo reproduction can be performed using only the three speakers 12L, 12R, and 13. And the low-frequency reproduction speaker 13
Are driven by a drive circuit close to the BTL connection, so that low-frequency enhanced reproduction in which the low frequency is enhanced by several dB can be easily realized. Further, capacitors CL and CR are used as low-frequency cutoff means.
And the inductor I is used as the middle and high frequency cutoff means, so that band filtering can be performed using the minimum necessary circuit elements, and a high-quality stereo reproduction apparatus is provided while suppressing the manufacturing cost of the entire apparatus. be able to.

In the above embodiment, the left channel audio signal is amplified by the non-inverting amplifier 14L and the right channel audio signal is amplified by the inverting amplifier 14R. However, the right channel audio signal is non-inverted. The configuration may be such that the signal is amplified by the amplifier 14L and the left channel audio signal is amplified by the inverting amplifier 14R.

[0017]

As described above, according to the present invention,
The audio signal of one channel of the stereo signal is non-inverted and amplified by a non-inverting amplifier, and the audio signal of the other channel is inverted and amplified by an inverting amplifier. Is connected to the first mid-high range reproduction speaker and the second terminal is connected to the output terminal of the inverting amplifier via the low range cutoff means.
And a low-frequency reproduction speaker connected in series between the output terminal of the non-inverting amplifier and the output terminal of the inverting amplifier together with the mid-high frequency cutoff means. And two inverting amplifiers can drive two speakers for each channel in the middle and high frequency reproduction and three speakers for low frequency reproduction common to both channels, and these non-inverting amplifiers. Both the inverting amplifier and the inverting amplifier amplify the audio signals of the left and right channels in the entire band, so that the amplifier function of the amplifier can be used to the maximum extent, unlike the conventional amplifier in which only a part of the band is amplified. Since the left and right channel audio signals are reproduced by the 3D method, which focuses on the point that the sense of direction of the stereo in the low frequency range is less than that in the middle and high frequency ranges, only the above three speakers are used. Similar stereo reproduction is possible, and since the low-frequency reproduction speaker is driven by a drive circuit close to the BTL connection, low-frequency enhancement reproduction in which the low frequency is enhanced by about several dB is possible, and the manufacturing cost of the entire device is reduced. An excellent effect is obtained such that a high-quality stereo playback device can be provided while being suppressed.

Further, according to the present invention, since a capacitor is used as the low-frequency cutoff means and an inductor is used as the middle and high-frequency cutoff means, band-pass filtering can be performed using the minimum necessary circuit elements, and the manufacturing cost of the entire apparatus is reduced. And an excellent effect such as being able to be suppressed.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing one embodiment of a stereo reproduction apparatus of the present invention.

FIG. 2 is a circuit configuration diagram showing an example of a conventional stereo playback device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Stereo reproduction apparatus 12L, 12R Speaker for middle and high frequency reproduction 13 Low range reproduction speaker 14L Non-inverting amplifier 14R Inverting amplifier CL, CR Low frequency cutoff capacitor I Medium high frequency cutoff inductor

Claims (2)

[Claims] 1. A non-inverting amplifier for non-inverting and amplifying an audio signal of one channel of a stereo signal, an inverting amplifier for inverting and amplifying an audio signal of the other channel of the stereo signal, and an output terminal of the non-inverting amplifier. A first mid-high range reproduction speaker to which the positive terminal is connected through the low band cut-off means, and a second middle-high range reproduction speaker in which the negative terminal is connected to the output terminal of the inverting amplifier through the low range cut-off means. A stereo reproducing apparatus comprising: a speaker; and a low-frequency reproduction speaker connected in series with an output terminal of the non-inverting amplifier and an output terminal of the inverting amplifier together with a mid-high frequency cutoff unit. 2. The low-frequency cutoff means is a capacitor,
2. The stereo reproducing apparatus according to claim 1, wherein said middle and high frequency cutoff means is an inductor.