DK177561B1

DK177561B1 - A sound transducer with a narrow directivity

Info

Publication number: DK177561B1
Application number: DKPA201200413A
Authority: DK
Inventors: Bjarne Soerensen
Original assignee: Bang & Olufsen As
Priority date: 2012-06-19
Filing date: 2012-06-19
Publication date: 2013-10-14

Abstract

This invention relates to a sound transducer construction that leads to a compact design including a tweeter, and with the assembled construction having a narrow directivity of sound distribution. In addition to that, a pair of identical sound transducers according to the invention defines a very specific stereo picture in a well-defined domain in front of a user. Means are included to enlighten the tweeter as an operational feature. Thus, the invention may advantageously be used for applications like multimedia systems applied in vehicles, boats, airplanes and alike, and in appliances like televisions, display screens, PC's, audio systems, and compact loud speakers, built into walls and ceilings and small compartments.

Description

DK 177561 B1 A sound transducer with a narrow directivity Technical field

This invention relates to a sound transducer construction that leads to a compact design 5 including a tweeter, and with the assembled construction having a narrow directivity of sound distribution. In addition to that, a pair of identical sound transducers according to the invention defines a very specific stereo picture in a well defined domain in front of a user.

Background of the Invention

Common speakers, especially speakers for the mid- and low frequency range (e.g.

10 woofers) have the disadvantage that they are deep compared to their actual diaphragm displacement. That becomes very obvious for applications like flat panel televisions or placed in a closed compartment e.g. in a door of a car. A loud speaker with a slim form factor and a controlled directivity is therefore desired.

15 Summary of the Invention

Normally it’s preferred to have a loudspeaker configuration in which the sound is distributed equally in a room either as left/right stereo image or as a multichannel surround system according e.g. to a 5.1 system.

Intentionally the mid-range and high-range sound fields are distributed broadly via 20 dedicated means. As disclosed by the applicant in US 5,615,176 an acoustical lens is applied to enhance the sound distribution in a room.

The current invention relates to a more narrow dispersion of sound, this being an advantage in smaller domains where the listening position primarily is fixed into one 25 specific point for one person. Par example this is relevant for persons seated in a car, where each of two persons in the front seats may receive dedicated sound fields from the corresponding sound transducers. One or more persons on the back seats may have the same options as well, i.e. dedicated sound transducer per person.

30 The car is described as an example, but the invention may be applicable in any smaller/closed compartment like small rooms, boats, and airplanes and alike, where a controlled narrow field of sound distribution is desired.

Prior art EP 1,193,999 A1 discloses a direct radiating sound transducer comprising a sound 35 transducer unit, an acoustic reflector placed in front of the sound transducer unit, a compartment including the sound transducer unit and support means connected to the acoustic reflector and the compartment.

Prior art US 3,965,455 A discloses a sound transducer comprising a sound transducer unit, 40 and acoustic reflector placed in front of the sound transducer unit and support means connected to the acoustic reflector.

A first aspect of the invention is a sound transducer with a narrow directivity and with a 45 compact form factor, the transducer characterized by: o a first object being a sound transducer unit including venting holes in the front surface of the unit, o a second object formed as an acoustic reflector placed in front of the first object, DK 177561 B1 o a third object being support means for the second object and connected to the second object, o a fourth object being a compartment for an assembly including the first object and support means for the second object, 5 o and where the third object is the fixation means for the first object, o and where the third object is connected to the fourth object, o and where the first object is a tweeter, o and where the second object includes light guide means configured to enlighten fully or partly the second object, and where the light is sourced 10 from means in the tweeter device.

The invention discloses a very compact sound transducer, and e.g. configured with four transducers, (two left stereo and two right stereo) in the front panel of a car, it provides a very precise stereo image for each of the two persons in the front seats.

In summary this is: an apparatus in which a first pair of two sound transducers each with a 15 narrow directivity provides a left stereo signal within a narrow range and an apparatus in which a second pair of two sound transducers each with a narrow directivity provides a right stereo signal within a narrow range and including a feature to enlighten the tweeter.

Brief Description of the Figures 20 Figure 1: Side view display of the objects according to the invention.

Figure 2: Cross section display of the sound reflector according to the invention.

Figure 3: Side view display of a transducer assembly according to the invention.

Figure 4: Principles in one embodiment providing a stereo sound image.

25 Thus, the primary objective of the invention is to disclose a compact tweeter device having a narrow but controlled dispersion of sound to listeners positioned at predefined and primarily fixed positions; this to obtain a perfect sound experience for each individual person.

30 The stereo picture for each person is realized by configuring a pair of transducer assemblies, one left and one right, per user. The reflectors for each of the sound transducers are shaped and directed towards each user accordingly.

Another aspect of the invention is a sound transducer: 35 · where the periphery of the second object mapped into an X,Y plane is circular or elliptical, and • where the upper part of the second object mapped into an Y,Z plane forms a contour that fully or partly constitutes a geometrical shape, e.g. a line, an elliptical curve or a circle, and 40 · where the lower part of the second object mapped into an Y,Z plane forms a contour that fully or partly constitutes a geometrical shape, e.g. a line, an elliptical curve or a circle.

2 DK 177561 B1

Yet another aspect of the invention is a sound transducer: • where the material of the second object is made by a non-stiff material, e.g. rubber, or 5 · where the material of the second object is made by a stiff material e.g.

plastic, glass or metal.

A further aspect of the invention is a sound transducer: • where the second object includes light guide means configured to enlighten fully or partly the second object, and 10 · where the light is sourced from means in the tweeter device.

In a preferred embodiment the invention as disclosed is part of a sound system in which a first pair of two sound transducers each with a narrow directivity provides a left stereo signal within a range of directivity from 10 deg. to 30 deg, and a sound system in which a 15 second pair of two sound transducers each with a narrow directivity provides a right stereo signal within a range of directivity froml 0 deg. to 30 deg.

Figure 1 displays a preferred embodiment of the invention. The embodiment including a compact standard loudspeaker transducer unit, e.g. a tweeter (11) having venting holes (19) through the front surface of the unit, an acoustic reflector (12) placed in front of the 20 tweeter. The reflector is connected to the tweeter via a tap (15) that fits into a hole (18) in the tweeter surface.

Fixation support means for the reflector (12) includes the mounting object (13), which in addition may serve as the support means for the tweeter (11), when the mounting object (13) is attached to the compartment object (14).

25 The primary function of the acoustical reflector (12) is to: • minimize air turbulence on the surface of tweeter (11), and • shape the sound dispersion from the tweeter to be narrow and directed towards a listening position of a user.

In a certain embodiment of the invention a requirement may be to have a reflector (12) to 30 indicate by a light signal the status of tweeter (11). In a preferred embodiment this feature is realized by a light source, e.g. an LED, inside the tweeter (11) and having the tap (15) of the reflector (12) to acts as a light guide into the reflector itself. Obviously the reflector in this embodiment must be made by translucent materials like acryl, glass or alike.

Figure 2 display details in the sound reflector object construction.

35 Fig 2.a displays a top view of the object, that mapped into an Χ,Υ,Ζ coordinate system, with the cut in an X, Y plane, the outer periphery of the reflector constitutes a circle (20). A support device may be adapted into a recess (21) for fixation of the reflector (12). The fixation means may be glue or a like.

3 DK 177561 B1

According to specific product requirement the size and the shape of the reflector may vary.

In the examples as disclosed the radius r1 of the circle (20) is approximately 5mm.

Fig 2.b displays a side view of the reflector object, that mapped into an Χ,Υ,Ζ coordinate system, with the cut in an X, Z plane.

5 Thus, the lower part of the second object mapped into the Y, Z plane forms a contour that fully or partly constitutes an elliptical curve, a parable curve or a circular form.

In the examples as disclosed the radius r2 of the curve (24) is approximately 3.7mm.

In the examples as disclosed the radius r3 for the circle of the perimeter (22) is approximately 2.5mm.

10 Thus, the upper part of the second object mapped into an Y, Z plane forms a contour that fully or partly constitutes an elliptical curve or a parable curve, or a line.

In the example as disclosed the curvature of the tilted surface (23) is linear according to industrial design aspect of an embodiment.

In the example as given the tilting angle “a” of the upper surface (23) is approximately 45°.

15 Figure 3 displays a side view of the assembly and details of the invention.

Figure 3.a is a view of an assembly of one embodiment which includes a transducer unit (11) an acoustic reflector (12) placed in front of the tweeter.

Fixation support means for the reflector (12) includes the mounting object (13), which in addition may serve as the support means for the tweeter (11), when the mounting object 20 (13) is attached to the compartment object (14).

Figure 3.b displays

The reflector is connected to the tweeter via a tap (15) that fits into a hole (18) in the tweeter surface (11). The tweeter has venting holes (19) in and through the tweeter unit.

Figure 4 displays a preferred embodiment being a configuration applied in a vehicle. Four 25 loudspeaker units (41,42,43,44) including tweeters according to the invention are mounted in the front panel of a car. Each of the loudspeaker units represents a left- or right stereo channel according to the configuration.

A stereo picture left and right for a first listener (1) is provided by one set of loudspeaker transducers (41,43) and a stereo picture left and right for a second listener (2) is provided 30 by another set of loudspeaker transducers (42,44).

To obtain the optimal sound quality as perceived by each user, the sound transducer reflectors are oriented towards the user according specific angles per user: • first user (1), left transducer (41) angled “a” degree.

• first user (1), right transducer (43) angled “b” degree.

35 · second user (2) , left transducer (42) angled “a” degree.

• second user (2), right transducer (44) angled “b” degree.

4 DK 177561 B1

Thus, a first pair of two sound transducers each with a narrow directivity provides a left stereo signal and a right stereo signal within a range of directivity from a first angle to a second angle.

In the example as given the first angle “a” is typically 15° and the second angle “b” is 5 typically 16°.

The invention may advantageously be used for applications like multimedia systems applied in vehicles, boats, airplanes and alike, and in appliances like televisions, display screens, PC’s, audio systems, and flat loud speakers, built into walls and ceilings. Thus, application areas are sound systems configured in close compartment.

10 5

Claims

1. An audio transmitter having a narrow radiation characteristic and having a compact form factor, and wherein the audio transmitter is characterized by:

2. A first object which is an audio transmitter unit in which 5 ventilating holes are included in the surface of the unit;

3. A second object designed as an acoustic reflector and located in front of the first object;

4. A third object, which is a support device for the second object, and is connected to this second object;

A fourth object, which is a compartment of a composite unit that includes the first object and support device for the second object, and

6. The second object includes light-emitting devices that are configured to fully or partially illuminate the second object and where the light source is fed from means in the device.