JPH0328637Y2 - - Google Patents

Description

[Detailed explanation of the invention] <Industrial application field> With the recent spread of video tape recorders (VTRs), video disks (VDs), and project-type televisions into general households, they have become popular as home entertainment or home theaters. There is a strong tendency to enjoy theatrical movies at home. This idea is
The present invention relates to a matrix 4-channel decoder that performs 4-channel reproduction using two transmission systems in a surround stereo sound reproduction system that is often used for sound field reproduction in such cases.

<Prior art and its problems> A very common type of surround 4-channel system is a discrete 4-channel system that combines a 4-channel decoder and 4-channel playback with 4 speakers and 4 amplifiers. However, this system not only requires four amplifiers (four channel amplifiers), but also requires a complicated control circuit to overcome poor channel separation, making the entire system extremely expensive.

Therefore, from an economical point of view, speaker matrix type 4 channel decoders have come into widespread use because they can provide matrix 4 channel reproduction by simply connecting speakers. An example of this is the book published by Nikkan Kogyo Shimbun on October 20, 1971, pages 53 to 4 channel stereo.
It is described on page 54. As shown in Fig. 3, the left and right front speakers LF and RF are directly connected to the channel output terminals +L, -L and +R, -R of the decoder D, respectively, and the left and right rear speakers LB and RB For this, one of the terminals of the same polarity is connected and the common connection point Y is connected to the output terminals -L and -R of the decoder D via a blending resistor VR for varying the matrix coefficient of the rear channel. It is connected to point X. When the resistance value of the blend resistor VR is set to infinity (open), reproduction close to a pseudo 4 channel can be performed in which difference signal components such as L-R and R-L are output from the rear speakers LB and RB. , the rear channel matrix coefficient is -1
approach. On the other hand, if the resistance value of the blend resistor VR is decreased so that it approaches zero, the matrix coefficient of the rear channel will also approach zero, and the same sound as the front channel will be produced, resulting in channel separation between the front and rear channels. becomes worse. In other words, the overall sound image localization is poor. In addition, in many recording systems, the low frequency components have recording characteristics close to monaural, so conventional speaker matrices 4 with the above configuration, where the volume of the rear channel is originally smaller than the volume of the front channel. Regarding the channel decoder, the reproduction of bass frequencies from the rear speakers LB and RB was extremely insufficient, and had the drawback of significantly detracting from the sense of realism.

In other words, in the case where only the blend resistor VR is connected, the frequency characteristic of the decoder output is
As shown by the dotted line in the figure, the level remains flat from the bass to the treble range, and the level only changes depending on the value of the blend resistance VR. Therefore, as mentioned above, if you play back a recorded source with the bass level suppressed, a lot of the high frequency range will be played from the rear speakers LB and RB, and most of the low frequency range will be played from the front speakers LF and RF. As a result, the overall balance between high and low frequencies was disrupted, leaving the listener feeling unsatisfied.

In view of the above circumstances, an object of the present invention is to provide a decoder that is economical and capable of producing four-channel reproduction with a sense of realism by providing a sufficiently rich range of low frequency reproduction by rear speakers.

<Means for Solving the Problems> The speaker matrix 4-channel decoder according to the present invention devised to achieve the above-mentioned purpose has two front speakers on the left and right, as shown in FIG. Each channel output terminal +L, -L and +R, to which LF and RF are directly connected,
An inductor I is connected in series to the blend resistor VR that connects the connection point X of one output terminal -L, -R of -R and the common connection point Y of the left and right rear speakers LB, RB.
It is characterized by the structure in which the two are connected.

<Operation and Effects of the Invention> According to the speaker matrix 4-channel decoder of the present invention having such a characteristic configuration, the high frequency range is attenuated and the low frequency range is attenuated due to the frequency impedance characteristic of the inductor I. As shown by the solid line in Figure 2, the low frequency range is enhanced (low-boosted). Furthermore, by adjusting the resistance value of the blend resistor VR, the bass range reproduction level can be adjusted as desired.

Therefore, by simply adding the inductor I and connecting the speakers, matrix 4 can be created.
While maintaining the economic efficiency of channel playback, even when recording near monaural, the low boost effect described above allows rear speakers LB and RB.
This enabled us to reproduce a sufficiently rich bass range, making it possible to reliably and easily reproduce realistic 4-channel stereophonic sound.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing a decoder of the present invention, FIG. 2 is an output-frequency characteristic diagram when Lch and Rch in-phase input is performed, and FIG. 3 is a conceptual diagram showing a conventional decoder. LB, RB...Rear speaker, LF, RF...Front speaker, VR...Blend resistance, I...
...Inductor, X...Connection point of output terminals -L and -R, Y...Common connection point of same polarity terminals of rear speakers.

Claims (1)

[Scope of utility model registration request] Each channel output terminal +L to which the left and right front speakers LF and RF are directly connected,
A common connection where the same polarity output terminals of -L, +R, -R -L, -R or +L, +R connection point X and the same polarity terminal of one of the left and right rear speakers LB, RB are connected. A speaker matrix 4-channel decoder in which point Y is connected through a blend resistor VR for varying the matrix coefficient of the rear channel, and between both connection points A speaker matrix 4-channel decoder characterized by connecting an inductor I for boosting.