WO2016098072A1

WO2016098072A1 - Loudspeaker for reverberant environments

Info

Publication number: WO2016098072A1
Application number: PCT/IB2015/059786
Authority: WO
Inventors: Daniele MELELLI
Original assignee: Melelli Daniele
Priority date: 2014-12-18
Filing date: 2015-12-18
Publication date: 2016-06-23

Abstract

The speaker (1) for reverberant environments comprises: - a support structure (2) able to define the body of the speaker (1); - at least a diffuser element (9) associated with the support structure (2) and having a front portion (9a) and a rear portion (9b) associated with each other, with the front portion (9a) able to realize a front emission of acoustic waves and with the rear portion (9b) able to realize a rear emission of acoustic waves; the speaker (1) also comprises variation means (11, 12, 13) of the rear emission adjustable between a first configuration wherein the rear emission is maximum and a second configuration wherein the rear emission is minimum.

Description

LOUDSPEAKER FOR REVERBERANT ENVIRONMENTS

Technical Field

The present invention relates to a speaker for reverberant environments.

Background Art

Today there are many types of speakers that differ by technical, geometric and constructive characteristics.

Despite their differences, most speakers have common elements.

Each speaker is made up of a set of one or more diffuser elements mounted on an empty prismatic speaker.

By speaker is meant the whole set of prismatic speaker-diffusers.

A diffuser element, or commonly known as a loudspeaker, is a transducer that converts the electrical signal coming from an amplifier into an acoustic signal.

A diffuser element usually has a frusto-conical shape and is inserted into the speaker so that the extremity with greater size (front) is arranged in the proximity of a side wall of the prismatic speaker and turned outwards, while the extremity with smaller size (rear) is inserted inside the speaker.

In this specification by the terms "front", "rear" and the like reference is made to the direction of orientation of the speakers during their normal use.

In particular, "front", "at the front" and the like refer to the direction from the diffuser directly to the listener.

"Rear", "at the rear" and the like refer to the direction opposite to that described above.

The diffuser element converts the electrical signal coming from an amplifier into an acoustic signal due to the oscillations of a special membrane which moves under the effect of a magnetic field induced by the electrical signal itself. The oscillations of this membrane create pressures and vacuums in the surrounding air that propagate in the form of acoustic waves, so as to generate the acoustic signal.

A diffuser element behaves as an acoustic dipole, that is, for each pressure/vacuum generated at the front (front emission) of the plane on which the membrane lies a corresponding vacuum/pressure is generated at the rear of the same plane (rear emission). The rear emission of the speaker is the more significant the lower the frequencies at which the diffuser element emits.

In general, for the diffusers emitting at medium frequency (approx. 3500 Hz) the rear emission of the speaker is particularly relevant and can cause annoyance to the quality of the sound perceived.

In particular, the rear emission of the speaker positioned in reverberant environments may cause the drawbacks associated with the interaction between the direct waves and the reflected waves (e.g. from the walls located behind the speaker), thus creating distortions and annoying disorders for the sound perception.

One drawback of known speakers, therefore, is linked to the phenomenon of reverberation, that is, to the possible overlapping of out-of-phase acoustic waves and the relevant reduction in the quality of the sound perceived by the listener.

Another drawback is linked to the fact that reverberation varies depending on the type of environment (room size and positioning of the speaker) and on the covering of the walls.

Wood paneled walls e.g. involve greater reflection than walls covered with carpets or other porous material.

Description of the Invention

The main aim of the present invention is to provide a speaker for reverberant environments that allows to adjust the rear emission to the type of environment in which it is positioned.

Another object of the present invention is to provide a speaker which allows to customize the features of the sound emitted both depending on the user's personal tastes and on the environment in which it is placed.

Another object of the present invention is to provide a speaker which allows to overcome the mentioned drawbacks of the prior art within the ambit of a simple, rational, easy, effective to use and affordable solution.

The objects stated above are achieved by the present speaker for reverberant environments having the characteristics of claim 1.

Brief Description of the Drawings Other characteristics and advantages of the present invention will become better evident from the description of two preferred but not exclusive embodiments of a speaker for reverberant environments, illustrated by way of an indicative but non-limiting example in the accompanying drawings in which:

Figures 3 and 2 are axonometric views of a detail of a first embodiment of the speaker according to the invention;

Figures 3 and 4 are sectional views of a detail of a first embodiment of the speaker according to the invention;

Figure 5 is an axonometric view of a detail of a second embodiment of the speaker according to the invention;

Figure 6 is a sectional view of a detail of a second embodiment of the speaker according to the invention.

Embodiments of the Invention

With particular reference to such figures, reference number 1 globally indicates a speaker for reverberant environments.

The speaker 1 comprises a support structure 2 able to define the body of the speaker itself.

As illustrated in Figures 1 and 2, the support structure 2 is composed of two side walls 3, a front wall 4 and a rear wall 5.

In the embodiments illustrated in the figures, the support structure 2 comprises a lower part 6 and an upper part 7.

The lower part 6 has a closed casing in which low-frequency diffuser elements 8 are accommodated as well as respective electrical devices needed for their operation (amplifiers, power supplies, acoustic filters, etc.).

The lower part 6 serves as the basis for the upper part 7.

In particular, this base is inclined and, as illustrated in Figures 3 and 4, has a greater inclination in the proximity of the front wall 4.

At the rear wall 5, the base has an irregular, knurled pattern, able to facilitate a phenomenon of random diffraction of the sound.

This way the sound emitted is not concentrated in a single point and therefore phenomena of disturbance are prevented.

Embodiments cannot be ruled out wherein the support structure 2 is completely closed or closed at the top.

The upper part 7, on the other hand, is open at the top and at the rear and houses a diffuser element 9 associated with the support structure 2 at the front wall 4. The diffuser element 9 has a front portion 9a and a rear portion 9b associated with each other, with the front portion 9a able to realize a front emission of acoustic waves and with the rear portion 9b able to realize a rear emission of acoustic waves.

Being the diffuser element 9 an acoustic dipole, the acoustic waves emitted at the rear are in phase opposition with respect to those emitted at the front.

This phenomenon is exploited to cancel reflection phenomena on top of the diffuser element 9.

Being the support structure open at the top, the rear and front acoustic waves propagate and therefore are canceled on top of the diffuser element 9.

This phenomenon is less important for high frequency acoustic waves, for this reason, on the front wall 4 is fixed an insert 10 which is placed on top of the diffuser element 9 and is able to deflect in the rear direction the high frequency acoustic waves that fail to go beyond the insert itself.

Advantageously, the diffuser element 9 is of the type of a loudspeaker emitting medium-high frequencies connected to electrical devices such as amplifiers, power supplies, etc. necessary to its operation and not represented in the figures. According to the invention, the speaker 1 comprises variation means 1 1, 12, 13 for varying the rear emission which are adjustable between a first configuration, illustrated in Figure 3, wherein the rear emission is maximum, and a second configuration, illustrated in Figure 4. wherein the rear emission is minimum. In particular, the variation means 1 1 , 12, 13 comprise at least one shielding element 11 able to partially dampen the rear emission.

In the present embodiments the shielding elements 1 1 are two in number, but solutions cannot be ruled out providing a single shielding element 11 or providing a plurality of shielding elements 11.

The shielding elements 11 are movable between an opening position and a closing position.

The opening position corresponds to the first configuration, while the closing position corresponds to the second configuration.

In the opening position, in fact, the shielding elements 1 1 are arranged in a horizontal position and intercept only a minimal part of the acoustic waves emitted at the back, leaving them go ahead freely.

On the contrary, in the closing position, the shielding elements 1 1 are arranged in a vertical position thus creating a barrier which intercepts most of the acoustic waves emitted at the rear.

In particular, the shielding element 1 1 is of the type of a plate movable between the opening position, wherein the plate is substantially horizontal, and the closing position, wherein the plate is substantially vertical.

The movable plate 11 is rotatable around a respective axis, substantially orthogonal to the side walls 3.

This way it is possible to vary the angle which identifies the position of the plate with respect to the vertical and therefore the orthogonal surface that intercepts the rear emission.

Conveniently, the shielding element is coated with sound-absorbing and/or sound-insulating material.

In particular, the surface of the shielding element 1 1 which, in the closing position, faces the speaker is coated with sound-absorbing material, e.g. polyurethane foam, so as to absorb part of the incident acoustic waves.

The opposite surface, on the other hand, is coated with sound-insulating material with high specific weight, such as lead or PVC, so as to counteract the occurrence of vibration and increase the insulating capacity of the shielding element 11.

Alternative solutions cannot be ruled out wherein, e.g., different materials are used provided that they have sound-insulating and sound- absorbing properties. Advantageously, the variation means 1 1 , 12, 13 comprise an adjusting system 12, 13 associated with the shielding element 1 1 and able to move the shielding element 11 between the opening position and the closing position.

In particular, the adjusting system 12, 13 comprises at least a first pulley 12 associated with the shielding element 1 1 and a second pulley 13 associated with an adjusting member 14. The first pulley 12 and second pulley 13 are kinematically connected to each other by means of a belt element 15 so as to transfer motion the one to the other and to ensure, therefore, the synchronized movement between the associated shielding elements 1 1.

The adjusting member 14 also comprises a shaft 16 having an adjusting knob 17 arranged externally to the support structure 2 and accessible to any user.

The shaft 16 is rotatable around a respective axis and is connected to the second pulley 13 so that, by turning the knob 17, the shielding elements 1 1 are rotated around a respective axis so as to take intermediate positions between the opening and closing ones or coincident with them.

By rotating, the shielding elements 1 1 determine a variation in the screening surface and i.e. in the surface orthogonal to the direction of the rear emission. This way it is possible to adjust the amount of rear emission intercepted.

In these embodiments, the shielding elements 11 and their first pulleys 12 are two in number and rotate in the same direction.

In addition, the shielding elements 1 1 have different sizes, suitable to the geometry of the speaker 1.

In particular, the shielding element 1 1 with larger dimensions is placed on top of the diffuser element 9 so that, in the opening position, the element itself can touch the front wall 4 and then close the support structure 2 on top.

This way, the rear acoustic waves which propagate on top of the diffuser element 9 are conveyed in the rear direction, improving the acoustic efficiency in case one wants to enhance rear emission.

Alternative solutions cannot, however, be ruled out wherein, e.g., the shielding elements 1 1 are more than two and with sizes different to those of the shielding elements 1 1 illustrated in the figures.

Solutions cannot also be ruled out wherein the shielding elements 1 1 rotate in opposite directions to one another.

The speaker 1 also comprises an auxiliary diffuser element 18 able to realize an auxiliary rear emission which allows to adjust the entire spectrum of the medium-high frequencies characterizing the rear emission.

In particular, the auxiliary diffuser element 18 is of the type of a high frequency diffuser element, e.g. a "tweeter".

The rear emission of acoustic waves in phase opposition, in fact, is negligible for frequencies approximately higher than a "cutoff value which is a function of the frequencies of the rear emission of the diffuser element 9.

This would result in an inability to control the emission for frequencies above the cutoff frequency.

The auxiliary diffuser element 18 is used to emit on frequencies higher than the cutoff frequency, thus ensuring an adjustment of the entire spectrum of the medium-high frequencies.

in the present embodiments the value of the cutoff frequency is approximately equal to 3500 Hz, but alternative solutions cannot be ruled out wherein the speaker 1 has characteristics that imply a different value of the cutoff frequency. In these embodiments, the auxiliary diffuser element 18 is placed on the rear surface of the lower part 6 so as to direct its emission at the rear of the speaker 1.

In particular, the auxiliary diffuser element 18 is arranged in the specular position with respect to the diffuser element 9 and both are off-centered with respect to the side walls 3.

This way there is a further randomization of the diffraction of the acoustic waves by the edge of the panel, with a consequent increase in the quality of the sound perceived.

The auxiliary diffuser element 18 is also connected to electrical devices such as amplifiers, filters, power supplies, etc. necessary to its operation.

Advantageously, the filter is centered on the value of the above-described cutoff frequency.

The auxiliary diffuser element 18 also has a diameter such that the emission of the element itself is sufficiently directional for frequencies higher than the cutoff frequency.

In particular, the value of the diameter is such that, for frequencies emitted above the cutoff value, the emission is found to have a dominant and therefore addressable direction of propagation.

In a first embodiment (Figures 1 to 4) the insert 10 is a bar having a cross section shaped as a triangle, in particular in the shape of a rectangular triangle. One of the two catheti is placed in contact with the front wall 4 and the insert 10 extends along the entire width of the latter.

This way, the inclined side of the insert 10 faces the shielding elements 1 1 and the diffuser element 9.

Such a feature allows the acoustic waves (within a certain range of frequencies), emitted by the diffuser element 9 and directed upwards, to be intercepted and diverted in the direction of the shielding elements 1 1 , allowing greater control of the sound.

In a second embodiment (Figures 5 and 6), the insert 10 comprises at least one intercepting extension 19 which extends in cantilever fashion from the support structure 2 on top of the diffuser element 9, in particular on top of the rear portion 9b.

In particular, the insert 10 comprises a plurality of intercepting extensions 19, spaced apart from each other and associated with at least one layer of sound- absorbing material arranged facing towards the shielding elements 1 1.

As shown in Figures 5 and 6, the intercepting extensions 19 are elements which extend in cantilever fashion from the front wall 4 towards the shielding elements 1 1.

In particular, the surface of the intercepting extensions 19 turned towards the shielding elements 1 1 is shaped so as to follow the rotation of the shielding element 1 1 placed in a higher position, so as to realize closed areas in which to reflect and dampen in a controlled manner the acoustic waves coming from the diffuser element 9.

Conveniently, the intercepting extensions 19 are arranged parallel to one another and equidistant to one another so that the insert 10 takes on a comb configuration.

All the intercepting extensions 19 are associated with one layer 20 of sound- absorbing material, e.g. ashlar or other shape, placed on top of the area in which the rear portion 9b of the diffuser element 9 is facing.

The shielding element 1 1 in a higher position, by rotating, slides on the absorbent material of the layer 20. This conformation allows the intercepting extensions 19 to intercept and partly dampen the acoustic waves emitted by the rear portion 9b and to deflect them towards the shielding elements 11.

The comb configuration allows a partial closure of the upper portion of the speaker 1.

Such partial closure allows the user greater control over the type of sound at output, expanding the possibility of choice.

In particular, the acoustic waves arriving from the rear portion 9b of the diffuser element 9 are filtered by the sound-absorbing layer 20 and, therefore, partly reflected by the intercepting extensions 19 towards the shielding elements 1 1. This solution allows greater control of the reflected acoustic waves, in particular of the acoustic waves directed upwards, resulting in increased control of the quality of the sound.

The alternative embodiment cannot be ruled out wherein the extension elements 19 are arranged adjacent to one another to form a single wall arranged on top of the diffuser element 9.

The operation of the present invention is as follows.

By turning the knob 17, the shielding elements 11 automatically rotate around the relevant axes by varying their position, and therefore the degree of opening between the elements themselves.

In particular, by turning the knob 17 varies the surface of the shielding elements

1 1 orthogonal to the direction of the rear emission and that intercepts the emission itself and dampens it.

This way it is possible to control the rear emission.

In the opening position, the above mentioned orthogonal surface is minimum and, therefore, the rear emission will be maximum.

Similarly, in the closing position the above mentioned orthogonal surface is maximum and, therefore, the rear emission will be minimum.

By turning the knob 17 it is possible to adjust the spectrum of emission between the two maximum and minimum values.

In case it is necessary to emit with higher frequencies than the cutoff frequency, the auxiliary diffuser element 18 is activated. The latter, by emitting at high frequencies, allows to extend the adjustment also to the spectrum of emission for higher frequencies than the cutoff frequency. In practice it has been found that the described invention achieves the proposed objects and in particular the fact is underlined that the speaker for reverberant environments allows to adjust the rear emission to the type of environment in which it is positioned.

In particular, by turning the knob and adjusting the tweeter, it is possible to change the frequency spectrum of the rear emission so as to adjust the emission itself depending on the environment in which the speaker is placed.

For high-reflective enviromnents the shielding elements will be rotated to the closing position.

For low-reflective environments the shielding elements will be rotated to the opening position.

The devised speaker, furthermore, in the light of what has been described, allows to customize the features of the sound emitted depending on both the environment in which it is placed, and on the user's personal tastes.

The latter, in fact, can adjust the opening of the shielding elements at will and simply by turning the knob.

Claims

1) Speaker (1 ) for reverberant environments, comprising:

a support structure (2) able to define the body of said speaker (1);

at least a diffuser element (9) associated with said support structure (2) and having a front portion (9a) and a rear portion (9b) associated with each other, with said front portion (9a) able to realize a front emission of acoustic waves and with said rear portion (9b) able to realize a rear emission of acoustic waves; characterized by the fact that it comprises variation means (1 1, 12, 13) of said rear emission adjustable between a first configuration wherein said rear emission is maximum and a second configuration wherein said rear emission is minimum.

2) Speaker (1) according to claim 1, characterized by the fact that said variation means (1 1, 12, 13) comprise at least one shielding element (1 1) able to dampen at least partially said rear emission, said shielding element (1 1) being movable between an opening position corresponding to said first configuration and a closing position corresponding to said second configuration.

3) Speaker (1) according to one or more of the preceding claims, characterized by the fact that said shielding element (1 1) comprises sound-absorbing and/or sound-insulating material.

4) Speaker (1) according to one or more of the preceding claims, characterized by the fact that said shielding element (11) is the type of a plate movable between said opening position, wherein said plate is substantially horizontal, and said closing position, wherein said plate is substantially vertical.

5) Speaker (1) according to one or more of the preceding claims, characterized by the fact that said variation means (1 1, 12, 13) comprise at least an adjusting system associated with said shielding element (1 1) and able to move said shielding element between said opening position and said closing position.

6) Speaker (1) according to one or more of the preceding claims, characterized by the fact that said adjusting system (12, 13) comprises at least a first pulley (12) associated with said shielding element (1 1) and a second pulley (13) associated with an adjusting member (14), said first pulley (12) and said second pulley (13) being kinematically connected to each other by means of a belt element (15).

7) Speaker (1) according to one or more of the preceding claims, characterized by the fact that said adjusting member (14) comprises a shaft (16) rotatable around a respective axis connected to said second pulley (13) and having an accessible adjusting knob (17).

8) Speaker (1) according to one or more of the preceding claims, characterized by the fact that it comprises a plurality of said shielding elements (1 1).

9) Speaker (1) according to one or more of the preceding claims, characterized by the fact that it comprises an auxiliary diffuser element (18) able to realize an auxiliary rear emission.

10) Speaker (1) according to one or more of the preceding claims, characterized by the fact that said auxiliary diffuser element (18) is of the type of a high frequency diffuser element.

1 1) Speaker (1) according to one or more of the preceding claims, characterized by the fact that it comprises at least one insert (10), placed on top of said diffuser element (9) and able to deflect high frequency acoustic waves.

12) Speaker (1) according to one or more of the preceding claims, characterized by the fact that said insert (10) comprises at least one intercepting extension (19) which extends in cantilever fashion from said support structure (2) on top of said rear portion (9b) of said diffuser element (9).

13) Speaker (1) according to one or more of the preceding claims, characterized by the fact that said insert (10) comprises a plurality of intercepting extensions (19), spaced apart from each other and having at least one layer (20) of sound- absorbing material arranged facing towards said shielding elements (1 1).