JPS5835440B2 - signal conversion circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention was first disclosed in Japanese Patent Application Laid-Open No. 52-40101 by the applicant company.
This invention relates to an improvement of the signal conversion circuit disclosed in the publication.

As is clear from the detailed description in Japanese Patent Application Laid-Open No. 52-40101, when a listener listens to a pinaural signal picked up by a dummy head through multiple speakers, As the pinaural signal to be supplied, it is necessary to use a modified pinaural signal that has a signal form in which crosstalk that should occur in the reproduction sound field is canceled in advance. A signal conversion circuit for converting a signal into a modified pinaural signal suitable for reproduction by a speaker is constructed by a combination of filters and delay circuits having complex frequency response characteristics.

The applicant's company has conducted various research in order to be able to provide a signal conversion circuit with a simple structure to obtain a modified pinaural signal suitable for reproducing the pinaural signal by a speaker. To,
A signal conversion circuit with a simple configuration as disclosed in Japanese Patent Application Laid-Open No. 5240101 mentioned above was completed.

That is, the signal conversion circuit disclosed in Japanese Patent Application Laid-Open No. 52-40101 focuses on the fact that signal components in the low frequency region do not play a very important role in the sense of localization of a sound image. This is an attempt to simplify the configuration of a signal conversion circuit by applying the concept of allowing crosstalk for unrelated signal components in the low frequency range. In this example, an input signal is divided into a low-frequency signal and a high-frequency signal using a low-pass filter and a high-pass filter.

The signal conversion circuit already proposed by the applicant's company was able to sufficiently achieve its intended purpose, but the previously proposed signal conversion circuit only requires a low-pass filter and a high-pass filter. In this respect, there was a need for further simplification of the configuration.

That is, a pair of low-pass filter, high-pass filter, and LJ used in the signal conversion circuit already proposed by the applicant company described in Japanese Patent Application Laid-Open No. 52-40101, As is clear from the description in Publication No. 52-40101, if a filter with a high cut-off frequency is used, the increase in low-frequency signal components when only one channel signal is input is minimized. However, the reproducing effect of the pinaural becomes weaker, and conversely, if a filter with a low cutoff frequency is used, the reproducing effect of the pinaural becomes good, but the Since the rise in signal components in For example, if the cutoff frequency is 200Hz,
A low-pass filter or high-pass filter with a cutoff characteristic of 12 dB10 ct or more is used.

However, as is well known, as filters have steeper cut-off characteristics, their configurations become more complex, requiring many parts, and their management becomes difficult.

The present invention is based on the signal conversion circuit proposed by the applicant company as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 52-40101, and which has a further simplified configuration. This was done for the purpose of obtaining the following:
The specific contents will be explained in detail with reference to the attached drawings.

1 and 2 are block diagrams of different embodiments of the signal conversion circuit of the present invention, and in each figure, 1 and 2 are inputs of each channel signal S, , Sl in the input pinaural signal. Terminals 3 and 4 are each channel signal (speaker signal) SPr of the modified pinaural signal.
, SPl output terminals, 5r=51 is the first sign addition adder 6r, 61 is the second sign addition adder, 7r, 71 is the transmission between the listener's ears in the reproduction sound field and the reproduction sound source. The ratio of characteristics, that is, the crosstalk characteristic B in the reproduction sound field

A circuit with characteristics approximately equal to B (hereinafter referred to as EA)
(sometimes referred to as circuits 7r, 71 having the characteristics of
In the figure, PSl and PS2 are phase shift circuits.

In the signal converting circuit of the first embodiment shown in FIG. Further, in the signal converting circuit of the second embodiment shown in the second figure, it is applied to the non-inverting input terminal of the first sign addition adder 5r via the phase shift circuit PS1.

In addition, the input signal Sr of one channel of the above-mentioned binaural signal supplied to the input terminal 1 is filtered through a low-pass filter L.
It is applied to the inverting input terminal of the second sign addition adder 6r via PF1.

The input signal Sl of the other channel of the pinaural signal supplied to the input terminal 2 is directly supplied to the non-inverting input terminal of the first sign adder 51 in the signal conversion circuit of the embodiment shown in the first figure. , is applied to the non-inverting input terminal of the first sign addition adder 51 via the phase shift circuit PS2 in the signal conversion circuit of the second embodiment shown in FIG.

The input signal s7 of the other channel of the binaural signals supplied to the input terminal 2 is passed through a low-pass filter LP.
It is applied to the inverting input terminal of the second sign addition adder 61 via F2.

The output signal of the first sign addition adder 5r described above is sent to the output terminal 3, and is also sent to the second sign addition adder 6 described above.
It is also applied to the non-inverting input terminal of r, and the above-mentioned first
The output signal of the sign addition adder 51 is sent to the output terminal 4 and is also applied to the non-inverting input terminal of the second sign addition adder 61 described above.

Further, the output signal from the second sign addition adder 6r described above is supplied to the inverting input terminal of the first sign addition adder 51 via a circuit 7r having a negative characteristic.
The output signal from the sign addition adder 61 is supplied to the inverting input terminal of the first sign addition adder 5r via a circuit 71 having a negative characteristic.

In the signal conversion circuit of the present invention configured as described above, each channel signal Sr, Sl of the binaural signal supplied to the input terminals 1 and 2 is transformed into each channel signal S of the modified binaural signal by signal conversion by the signal conversion circuit.
Pr and SPY are sent out from the output terminals 3 and 4, and the relationship between the above-mentioned output signals in the signal conversion circuit is expressed by the following equations.

First, the relationship between the person and the output signal in the signal conversion circuit shown in FIG. 1 is expressed by the following equation (1).

5Pr=Sr+i・(3LPF2・Sl−; −5P
Y)...(1) SPl=Sl+i HGLPFI・5r-i-8P.

However, in the above equation (1), GLPF2゜GLP
Fl is a low-pass filter LPF2. This is the transfer characteristic of LPF1.

Further, the relationship between the person and the output signal in the signal conversion circuit shown in the second diagram is expressed by the following equation (2).

5Pr=GPs1・Sr16・GI, PF2・sl−λ
・5Pl)...(2) SPl-GPs2・Sl ten yuan・GLPFl.

Sr-Ten・sPrHowever, in the above equation (2), G
LPF2 = GLPFI is a low pass filter LPF2. LPF
1, and GPS1 and GPS2 are the transfer characteristics of the phase shift circuits PS1 and PS2.

By the way, the phase shift circuit PS1. Since the transfer characteristic (frequency response characteristic) of Ps2 and the transfer characteristic (frequency response characteristic) in the passband of low-pass filter LPF1LPF2 are approximately 1, in the above equations (1) and (2), GPSI = GPS2 =GLPF1 =GLPF2
When = 1 is substituted, the above equations (1) and (2) both become as shown in the following equation (3).

Bsp=s+-・5l--・5Pl r r A A B B )...(3) SPl=Sz+天°S-=νSP・ That is, the present invention shown in FIGS. 1 and 2 The signal conversion circuit includes a low-pass filter LPF1. In the frequency range of the passband of LPF2, the output characteristics of the person are as shown in (3) above.
) is expressed by the formula.

When the above equation (3) is modified and rearranged, the following equation (4) is obtained, and B B sp +-・5Pl=S, +-・Sl r A A )...(4) B B SPY +-・5Pr = Sg + ¥ ・Sr Expressing equation (4) as a determinant, it becomes equation (5) below.

Since this value is not 0, the above equation (5) becomes the following (
6) The formula is as follows.

SP = S r r) ... (6) SPl = Sl In this way, even in the signal conversion circuit of the present invention of the type shown in Figs. 1 and 2 that does not use a high-pass filter, the low-pass filter L
No signal conversion operation is performed on the signals in the passbands of PF, LPF2, and therefore the signal conversion circuit of the present invention is similar to the signal conversion circuit described in JP-A-52-40101 mentioned above. This indicates signal conversion characteristics.

In the signal conversion circuit of the present invention, the above-mentioned Japanese Patent Application Laid-Open No. 52-40
Since the high-pass filter required in the signal conversion circuit described in Japanese Patent No. 101 can be omitted, the configuration of the signal conversion circuit can be further simplified.

In addition, in the embodiment circuit of the present invention shown in the second diagram, the phase shift circuit PS
1. I am using PS2, which is a low pass filter LPF.
1. The signal in the frequency domain near the cut-off frequency in LPF2 is passed through the low-pass filter LPF 1. This phase shift circuit PS1. is provided to prevent the phase shift received when passing through the LPF 2 from having an adverse effect on the signal conversion characteristics. P
As S2, a low pass filter LPF1. A filter having the same phase characteristics as LPF2 is used. For example, when a second-order low-pass filter with a Q of 0.5 is used as a low-pass filter, a first-order low-pass filter is used as a phase shift circuit. It is sufficient to use a phase shift circuit.

The phase shift circuit can have a circuit configuration as shown in Fig. 3, that is, one composed of an operational amplifier OP, resistors R, RF, RG, and a capacitor C. 4.The number of component parts is smaller than that of a high-pass filter configured as shown in the figure, that is, a high-pass filter configured with an operational amplifier OP, resistors R1, R2, RF, and capacitors CI and C2. , the phase shift characteristics are determined by two components, the resistor R and the capacitor C. Therefore, in implementing the present invention, even if a phase circuit is used, the previously proposed signal using a high-pass filter is The configuration of the signal conversion circuit is still simpler than that of the conversion circuit, and it is also advantageous from the point of view of component management.

As is clear from the above detailed explanation, the signal conversion circuit of the present invention is an improvement on the signal conversion circuit previously proposed by the applicant company, and can be realized with a simpler configuration. According to the present invention, a signal conversion circuit with excellent characteristics can be provided easily and at low cost.

[Brief explanation of drawings]

1 and 2 are block diagrams of various embodiments of the signal conversion circuit of the present invention, FIG. 3 is a connection diagram of an example of a phase shift circuit, and FIG. 4 is a diagram of an example of a high-pass filter. It is a connection diagram. 1.2...Input terminal for pinaural signal, 3゜4...Output terminal for modified pinaural signal, 5r
. ! M, 6r, 6n... sign addition adder, rr, r
l...Circuit with characteristics of 8, LPFl, LP
F2...Low pass filter, PSl, PS2...
...Phase shift circuit, OP... operational amplifier.

Claims (1)

[Claims] 1. The reproduced sound is reproduced so that the acoustic signals given to both ears of the listener through the space from the plurality of speakers are in the form corresponding to the pinaural signal to be reproduced. In a signal conversion circuit, the output signal of each channel of the circuit is sent to the speaker as a modified pinaural signal, which has a signal form that can cancel out the crosstalk that should occur in the field. The crosstalk is mixed into other channels in opposite phases through a circuit that has characteristics approximately equal to the crosstalk characteristics in the reproduction sound field, which is indicated by the ratio of the transmission characteristics between both ears and the reproduction sound source. By mixing the low-frequency signal components of the input signal into other channels in the same phase through a circuit having characteristics approximately equal to the crosstalk characteristics in the reproduced sound field described above, it does not significantly affect the sense of localization of the sound image. A signal conversion circuit that can cancel in advance crosstalk that should occur in a reproduction sound field only for signal parts in a frequency band excluding signal parts in a low frequency band. 2. A means for applying the input signal of each channel to a non-inverting input terminal of a first sign adder provided individually for each channel, and an output signal of the first sign adder provided separately for each channel. means for applying the input signal to the output terminal of each channel individually and to the non-inverting input terminal of a second sign adding adder provided for each separate channel, and low-pass filtering the input signal of each channel. means for individually supplying the signals to the inverting input terminals of the second sign addition adders provided for each of the above-mentioned different channels through a device; The output signals of the receiver are transmitted to each other through a circuit having characteristics approximately equal to the crosstalk characteristics in the reproduced sound field, which is the ratio of the transfer characteristics between the listener's ears in the reproduced sound field and the reproduced sound source. 2. The signal conversion circuit according to claim 1, further comprising means for applying the signal to an inverting input terminal of a first sign adding adder in the channel. 3 means for applying the input signal of each channel to a non-inverting input terminal of a first sign addition adder provided individually for each channel via a phase shift circuit, and an output of the first sign addition adder; means for individually applying the signal to the output terminal of each separately provided channel and to a non-inverting input terminal of a second sign addition adder provided for each separate channel; means for individually applying the input signal to the inverting input terminal of the second sign adder provided for each of the above-mentioned separate channels via a low-pass filter; A circuit that converts the output signal of the second code addition adder into a crosstalk characteristic that is approximately equal to the crosstalk characteristic in the reproduced sound field, which is represented by the ratio of the transfer characteristics between the listener's ears in the reproduced sound field and the reproduced sound source. a signal converting circuit comprising means for supplying signals to inverting input terminals of first code adders in mutually other channels via a plurality of channels.