EP1104221B1 - Sounding device - Google Patents

Abstract

Loudspeakers in general, and including those used in audio equipment e.g. for application in motor vehicles, suffer from the shortcoming of not being able to intrinsically vary their acoustic radiation characteristic, and any change obtained is at the cost of changing the position of the loudspeaker, or incorporating some sort of aid, such as acoustic reflectors, a signal summation stage etc. To change the loudspeaker acoustic emission characteristic more easily, the acoustic radiation characteristic of two loudspeakers (1,2) is made dependent of the evaluation (weighting) of the input signals (E1,E2).

Description

The invention relates to a sound system with four speakers.

Each speaker has a substantially unchangeable radiation characteristic. When using loudspeakers in public address systems, their emission characteristics can only be influenced to a limited extent by a suitable arrangement of the loudspeakers in the room and / or by additional mechanical aids such as, for example, acoustic reflectors or acoustic lenses. A special challenge in this case are PA systems in motor vehicles, since on the one hand, the locations for mounting the speakers are usually not freely selectable and on the other hand, the space for additional mechanical aids is not sufficient. In addition, the room to be sounded is usually relatively small, so that, for example, in stereophonic sounding sufficient channel separation is often not sufficient, especially for multiple listeners.

In the JP 07-046 698 A a circuit arrangement is shown with a left and a right Tonsignalkanal, each of which has a summation stage in which the original Tonkanalsignal each a phase-shifted and amplitude-changed portion of the audio signal from the counter-channel is mixed (cross-coupling).

The JP 06-315 198 A shows a similar circuit, in which additionally a control means for adjusting the amplifier and the phase shifter is provided in the cross-over coupling branches. Also here are speakers at the outputs the circuit shown. The JP 06-315 198 A thus shows a device in which sums of different in amplitude and phase differently rated input signals are formed.

The JP 04-337 999 A discloses an arrangement with a plurality of loudspeakers, which are controlled by means of phase shifters, by means of which the radiation direction of the loudspeakers can be changed.

In the US 5,305,386 A , especially FIG. 4 (2) a circuit is shown with cross-coupling branches in which attenuators and phase shifters are included. This circuit part is included in an overall circuit for expanding and controlling sound images ("sound fields").

Also the subject of WO 97 30 466 A1 aims to image virtual sound sources at given locations. At the same time, the beam angle enclosed by the loudspeakers (eg 10 degrees) is considered. For this purpose filter circuits H1 (z) or H2 (z) are provided both in the main branches and in the cross-coupling branches, which effect phase shifts.

The JP 01-151399 describes a device for increasing the sound pressure in low frequency ranges at certain listening positions.

Finally, out of the JP 02-241 296 A an arrangement with four speakers known, which are arranged in front of the driver and the front passenger in a car and operated so that both can perceive a useful stereo sound image. In this arrangement, however, no phase shifters and no cross-couplings are provided.

The object of the invention is therefore to provide a sound system whose radiation characteristics without change in position the speaker and without additional mechanical aids is changeable.

The object is achieved by a sound system according to claim 1. refinements and developments of the inventive concept are the subject of dependent claims.

Advantage of the invention is that the emission characteristics can be changed by electronic means and therefore the necessary device has a relatively small footprint, does not have to be located in the vicinity of the speakers and is easy to mass produce.

This is achieved in detail by a sound system with four loudspeakers and at least one signal conditioning device controlled by two input signals for generating control signals for the respective two loudspeakers, wherein the control signals are equal to the sum of the input signals respectively differently evaluated in amplitude and phase are such that the radiation characteristic of the respective two speakers depends on the evaluation of the input signals. The signal conditioning device can be realized in analog and / or digital circuit technology alike. By varying the phases and / or attenuations / amplifications, the desired emission characteristic can thus be set.

Preferably, the signal conditioning device comprises two adders, each of which is supplied with the interposition of a first phase shifter and a first coefficient member each one of the input signals and the interposition of a second phase shifter and a second coefficient member the respective other input signal. This allows the separate setting of all phases and amplitudes with little effort.

In particular, in the case of stereophonic input signals, the first and second phase shifters preferably produce identical phase shifts and the first and second coefficient members respectively produce equal attenuations / gains.

In a further development of the invention phase shifters are used which generate frequency-independent phase shifts. In particular, so-called Hilbert transformers are used as phase shifters which generate a frequency-independent phase shift of 90 degrees. However, the phase shifts are preferably variable. The 90 degree out of phase signal may be appropriately mixed with the original signal to obtain a signal of arbitrary phase shift at constant amplitude. As a result, a simple adjustment of the phase shift is achieved without the frequency response of the individual speaker is changed by the drive signal itself. However, it is also possible to use phase shifters which effect a frequency-independent phase shift at least only in a certain frequency range, the frequency shift in the other frequency ranges being tolerated. Apart from that, in certain cases, however, a specific frequency dependence of the drive signal may be desired, for example if it is possible to compensate for deficits in the frequency response of the loudspeaker. As a phase shifter suitably designed analog and / or digital filters are used.

In another embodiment of the invention, the two speakers are arranged between the two other speakers, the Hauptabstrahlrichtungen the two are set a speaker at a certain angle to the vertical away from each other in the direction of the other speakers. Preferably, the main radiation directions of the other speakers are at a certain angle to the vertical in the direction of a speaker. Alternatively, the one two speakers but also be arranged next to the two other speakers, the Hauptabstrahlrichtungen the two are a speaker and the other two speakers are set at a certain angle to the vertical in each direction. This makes it possible, for example, for two listeners each achieve optimal adaptation.

Finally, the other speakers can also be preceded by a (further) signal conditioning device in order to enable a simple adjustment of the emission characteristic even in the case of the other loudspeakers.

Figur 1

eine Ausführungsform einer Signalaufbereitungsein- richtung für eine erfindungsgemäße Beschallungsein- richtung,

Figur 2

eine bevorzugte Ausführungsform einer erfindungsge- mäßen Beschallungseinrichtung,

Figur 3

eine Alternative zur Ausführungsform nach Figur 2 und

Figur 4

eine weitere Alternative zur Ausführungsform nach Figur 2.

The invention will be explained in more detail with reference to the embodiments illustrated in the figures of the drawing. It shows:

FIG. 1

an embodiment of a signal conditioning device for a PA according to the invention,

FIG. 2

a preferred embodiment of a sounding device according to the invention,

FIG. 3

an alternative to the embodiment according to FIG. 2 and

FIG. 4

a further alternative to the embodiment according to FIG. 2 ,

In the exemplary signal conditioning device 5 after FIG. 1 two speakers 1 and 2 are each driven by one of two stereophonic input signals E1, E2 with the interposition of a respective power amplifier 3, 4. The power amplifiers 3, 4 are preceded by a signal conditioning device 5, to which the input signals E ₁ and E _{2 are} supplied. In the signal conditioning device 5, the input signal E _{1 is} fed to an adder 8 via a phase shifter 6 with a frequency-independent phase shift φ ₁ and via a coefficient element 7 with a coefficient K ₁ representing an attenuation or gain. In addition, the adder 8 receives the input signal E ₂ with the interposition of a phase shifter 9 with a frequency-independent phase shift φ ₂ and a coefficient element 10 with a coefficient K ₂ representing an attenuation or amplification. The adder 8 generates therefrom a drive signal A ₁ for the power amplifier 3. In an analogous manner, the input signal E _{2 is} supplied to an adder 13 via a phase shifter 11 with the frequency-independent phase shift φ ₁ and via a coefficient element 12 with the coefficient K ₁ . The adder 13 also receives, with the interposition of a phase shifter 14 with the frequency-independent phase shift φ ₂ and a coefficient element 10 with the coefficient K _2, the input signal E ₁ and generates therefrom a drive signal A ₂ for the power amplifier.

$${\mathrm{A}}_2\mathrm{=}{\mathrm{K}}_{\mathrm{1}}\mathrm{\cdot }{\mathrm{E}}_2\left({\mathrm{\varphi }}_{\mathrm{1}}\right)\mathrm{+}{\mathrm{K}}_{\mathrm{2}}\mathrm{\cdot }{\mathrm{E}}_1\left({\mathrm{\varphi }}_{\mathrm{2}}\right)$$

The input signals E ₁ and E ₂ are thus respectively supplied to two phase shifters 6, 9 and 11, 14, which generate the phase shifts φ ₁ and φ ₂ . Thereafter, the phase-shifted input signals E ₁ and E _{2 are} evaluated with the coefficients K ₁ and K ₂ acting as weighting factors, and then "cross-over" - the drive signals A ₁ and A ₂ resulting - added. After amplification, the control signals A ₁ and A ₂ are supplied to the speakers 1 and 2. FIG. Expressed formally, A ₁ and A ₂ behave as follows depending on E ₁ and E ₂ , K ₁ and K ₂ , φ ₁ and φ ₂ : $${\mathrm{A}}_{\mathrm{1}}\mathrm{=}{\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">K</figure-callout>}}_{\mathrm{1}}\mathrm{\cdot }{\mathrm{<figure-callout\; id="1"\; label="e"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">e</figure-callout>}}_{\mathrm{1}}\left({\mathrm{<figure-callout\; id="1"\; label="\phi "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\phi </figure-callout>}}_{\mathrm{1}}\right)\mathrm{+}{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">K</figure-callout>}}_{\mathrm{2}}\mathrm{\cdot }{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">e</figure-callout>}}_{\mathrm{2}}\left({\mathrm{\phi }}_{\mathrm{2}}\right)$$

$${\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">A</figure-callout>}}_2\mathrm{=}{\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">K</figure-callout>}}_{\mathrm{1}}\mathrm{\cdot }{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">e</figure-callout>}}_2\left({\mathrm{<figure-callout\; id="1"\; label="\phi "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\phi </figure-callout>}}_{\mathrm{1}}\right)\mathrm{+}{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">K</figure-callout>}}_{\mathrm{2}}\mathrm{\cdot }{\mathrm{<figure-callout\; id="1"\; label="e"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">e</figure-callout>}}_1\left({\mathrm{<figure-callout\; id="2"\; label="\phi "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\phi </figure-callout>}}_{\mathrm{2}}\right)$$

Due to the phase condition of the two drive signals A ₁ and A ₂ , the distance of the speakers 1 and 2 to each other and the distance of the listener to the speakers 1 and 2 now occurs on a shift of the main beam direction, in FIG. 1 is represented by two lobes 16 and 17. Since some of the Hauptabstrahlrichtung determining parameters such as the predetermined by the fixed installation of the speakers 1 and 2 in a vehicle distance between both and given by an approximately fixed position of the listener fixed distance of the listener to the speakers 1 and 2 are at a presumed constant Volume usually the phase shifts φ ₁ and φ _2, the preferred points for adjusting the azimuth of Hauptabstrahlrichtungen.

According to the embodiment FIG. 2 are out of the speakers 1 and 2 in conjunction with the signal conditioning device 5 off FIG. 1 two more speakers 18 and 19 are provided. These are driven directly by the input signals E ₁ and E ₂ , the input signal E ₁ forming the left channel L and the input signal E ₂ forming the right channel R of a stereophonic signal. The other speakers 18 and 19 are arranged left and right of the speakers 1 and 2 in such a way that the lobes 20, 21 of the main emission directions are directed inwardly to the speakers 1 and 2 out. The lobes 16 and 17 of the speakers 1 and 2 are directed more outward, away from one another. This results in an undisturbed stereo impression for two listeners 22 and 23, respectively, since the loudspeakers 2 and 18 represent the left channel L and the loudspeakers 1 and 19 the right channel, the loudspeakers 1 and 18 the handset 22 and the loudspeakers 2 and 19 sonicating the listener 23. In this embodiment, it is assumed that the speakers 18 and 19 can be installed in a suitable manner to produce the desired radiation characteristic.

If this is not possible, then the arrangement can FIG. 2 as in FIG. 3 be changed shown. The loudspeakers 18 and 19 are preceded by a signal conditioning device 24, which is constructed, for example, like the signal conditioning device 5, and the emission characteristic is set so that the lobes 20 and 21 are directed more inwards.

In order to be able to individually adapt the radiation characteristic to each listener, the arrangement can finally change FIG. 3 according to FIG. 4 be amended to the effect that the speakers 1 and 2 or 18 and 19 are arranged in pairs next to each other. In this case, the loudspeakers 1 and 2 sound the receiver 23 and the loudspeakers 18 and 19 the listener 22. The lobes 20 and 21 or 16 and 17 are each inclined towards each other.

Claims (9)

1. A sounding device with four loudspeakers (1, 2, 18, 19) and at least one signal processing device (5), which is connected in series before two of the four loudspeakers (1, 2) and is controlled by two input signals (E₁, E₂), for producing control signals (A₁, A₂) for the (respective) two loudspeakers (1, 2), which are in each case equal to the sum of the input signals, (E₁, E₂) which are rated differently in their amplitude and phase, wherein the radiation characteristic of the (respective) two loudspeakers (1, 2) depends on the rating of the input signals (E₁, E₂), wherein the four loudspeakers (1, 2, 18, 19) are arranged next to one another, wherein a left hand and a right hand pair of loudspeakers is defined and wherein the radiation lobes (16, 17, 20, 21), which define the main radiation directions, of the respective loudspeakers of the two pairs of loudspeakers are inclined to one another.
2. A sounding device as claimed in claim 1, in which the signal processing device (5) has two adders (8, 13), to which are supplied a respective one of the input signals (E₁, E₂), with the interposition of a first phase shifter (6, 11) and a first coefficient element (12) and the respective other input signal (E₁, E₂) with the interposition of a second phase shifter (9, 14) and a second coefficient element (10, 15).
3. A sounding device as claimed in claim 2, in which the first and second phase shifters (6, 11; 9, 14) produce in each case the same phase shifts (ϕ₁,ϕ₂) and the first and second coefficient elements (7, 12; 10, 15) produce in each case the same attenuation/amplification (K₁, K₂).
4. A sounding device as claimed in one of the preceding claims, in which the phase shifters (6, 11; 9, 14) produce frequency-independent phase shifts (ϕ₁,ϕ₂).
5. A sounding device as claimed in one of the preceding claims, in which the phase shift (ϕ₁,ϕ₂) is variable.
6. A sounding device as claimed in one of claims 1 to 5, in which two of the loudspeakers (1, 2) are arranged between the two other loudspeakers (18, 19), wherein two inner loudspeakers (1, 2), which are connected in series after the signal processing device (5), and two outer loudspeakers (18, 19) are defined and the main radiation directions of the two inner loudspeakers (1, 2) are set at a predetermined angle to the vertical away from one another in the direction of the outer loudspeakers (18, 19).
7. A sounding device as claimed in claim 6, in which the main radiation directions of the outer loudspeakers (18, 19) are situated at a predetermined angle to the vertical in the direction of the inner loudspeakers (1, 2).
8. A sounding device as claimed in one of claims 1 to 5, in which the signal processing device (5) is connected in series before the right hand pair of loudspeakers and which has a further signal processing device (24), which is connected in series before the left hand pair of loudspeakers.
9. A sounding device as claimed in claim 6 or 7, which includes a further signal processing device (24), which is connected in series before the outer loudspeakers (18, 19).

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