RU2250573C1 - Acoustical device - Google Patents

Abstract

FIELD: electroacoustics; acoustical systems for domestic and professional applications.

SUBSTANCE: proposed acoustical system has basket with moving-coil loudspeaker and acoustical baffle disposed behind the latter. Acoustical baffle is made in the form of truncated cone enclosing entire surface of loudspeaker and has transverse slot on side surface. Acoustical baffle base is secured on front wall of basket over loudspeaker perimeter and its top is joined with loudspeaker magnetic system; acoustical baffle surface is made of sound-absorbing material. Transverse slot is made on acoustical baffle perimeter so that it divides the latter into two members. Top member joined with loudspeaker magnetic system has concave edge. Transverse slot may be disposed in bottom part of acoustical baffle with its edges overlapping and gradually bent out apart, bottom edge being bent out from loudspeaker.

EFFECT: enhanced audio quality due to reduced stray acoustic radiation on loudspeaker in low audio-frequency range.

4 cl, 6 dwg

Description

The invention relates to the field of electroacoustics and can be used in high-quality acoustic systems for domestic and professional use.

Known acoustic column according to patent No. 2148818, H 04 R 1/28, Russia, published on 10/01/1999, comprising a housing in the form of a monolithic prism with mounting cavities of sound-absorbing material and speakers located in these cavities.

The disadvantage is the small working volume inside the case due to its high filling with dense sound-absorbing material in the absence of a gap for its compensation. As a result of this, during operation of the speaker in the region of low sound frequencies, an excess or lack of pressure is formed inside the housing, which restrains the vibrations of the moving speaker system and reduces the efficiency of the speaker.

A device is also known for acoustic design of dynamic heads according to utility model No. 25132, H 04 R 1/28, Russia, published on September 10, 2002, adopted as a prototype and comprising a housing, a speaker and a perforated rectangular acoustic screen located behind it at a distance.

The disadvantage is spurious acoustic radiation from the walls of the housing and the screen, because a large distance from the speaker to the screen causes resonant oscillations in the low-frequency region, proportional to this distance, which are not absorbed by sound-absorbing material. Since the inner surface of the housing is not covered with sound-absorbing material, the damping of acoustic radiation incident on it is not effective.

In addition, the perforation of the screen facilitates direct and free penetration (along a direct path) to the dynamics of spurious acoustic radiation reflected from the walls of the housing behind the screen, causing resonant oscillations of the system.

Thus, the location of the screen in relation to the speaker and the entire design of the device does not provide effective damping of spurious acoustic radiation in the low frequency region, which reduces the sound quality.

The objective of the invention is to improve the sound quality by reducing the impact of spurious acoustic radiation in the field of low sound frequencies on the speaker.

The acoustic device comprises a housing with a speaker and an acoustic screen located behind it.

Unlike the prototype, the acoustic screen is made in the form of a truncated cone covering the entire surface of the speaker, with a transverse slit on the side surface, the base of the acoustic screen is fixed to the front wall of the housing along the perimeter of the speaker, and the top is paired with the speaker’s magnetic system, the surface of the acoustic screen is made of sound-absorbing material.

The transverse gap is made around the perimeter of the acoustic screen and divides it into two elements.

The upper element of the acoustic screen, coupled with the magnetic system of the speaker, is made with a concave edge.

The transverse gap can be located at the bottom of the acoustic screen, its edges are overlapped and smoothly bent away from each other, and the lower edge is bent away from the speaker.

The implementation of the screen in the form of a truncated cone and securing it around the perimeter of the speaker allows you to cover the speaker, as close as possible to it from all sides, and create a small limited volume around it. This increases the frequency of sound vibrations inside the volume of the cone when they collide with the screen.

The resulting high-frequency resonances effectively dampens the sound-absorbing material of the screen inside the volume formed by it.

The transverse gap in the acoustic screen compensates for the small volume around the speaker, providing normal pressure inside the system. Performing a slit around the perimeter of the screen normalizes the pressure around the speaker and eliminates distortion of the moving system, especially with a large diameter of the speaker - more than 200 mm. With a speaker diameter of up to 200 mm, a gap at the bottom of the screen is sufficient to normalize internal pressure.

In addition, the location of the slit on the inclined surface of the cone virtually eliminates the direct penetration of spurious resonances to the speaker, and only a small part of the attenuated sound vibrations reaches the speaker, but along a curved path, which further weakens their effect.

The implementation of the upper element of the screen with a concave edge prevents the reflected wave from rolling into the slit and ensures their flow into the concavity bowl, reducing the impact of spurious acoustic radiation on the speaker.

The implementation of the edges of the slit of the screen smoothly bent away from each other provides a section of the slit, smoothly expanding at the input and output, i.e. the slit has a cross section that gradually expands from the center to the edges. The echo prevents the occurrence of vortex flows at the entrance and exit of the gap, eliminating the modulation of the acoustic resistance of the gap and the excess noise in the device, which improves the sound quality.

The edge of the slot bent away from the speaker repels the acoustic vibrations that fall on it, weakening them.

The implementation of the inner surface of the housing of sound-absorbing material provides the attenuation and / or damping of the sound vibrations that fall on it, which also prevents the formation of resonances inside the housing. All this improves the sound quality.

Thus, all the hallmarks are significant and solve the problem.

The proposed device is presented in the drawings.

Figure 1 Acoustic device with the location of the slit around the perimeter of the screen.

Figure 2 Acoustic device with an upper screen element made with a concave edge and with the location of the slit around the perimeter of the screen.

Figure 3 Section aa in figure 1 and 2.

Figure 4 Acoustic device with the location of the slit in the lower part of the screen.

Fig. 5 Section B-B in Fig. 4

Fig.6 Node section of the slit in figure 4 (enlarged).

The acoustic device comprises a housing 1, inside which a speaker 2 and an acoustic screen 3 located behind it are mounted, made in the form of a truncated cone with a transverse slit 4 on the side surface. The base of the screen 3 is fixed to the front wall of the housing 1 around the perimeter of the speaker 2, and the top 5 is connected to the magnetic system of the speaker 1. The acoustic screen 3 is made of hard material, such as metal, wood, etc. The surface of the screen 3 and the inner surface of the housing 1 are covered with sound-absorbing material 6, FIGS. 1, 2. When the diameter of the speaker is more than 200 mm, use the option of a slot 4 made along the perimeter of the screen 3, FIGS. 1-3. The upper screen element can be made with a concave edge 7, figure 2, or with a straight edge 8, figure 1. When the diameter of the speaker is less than 200 mm, you can use the options for making slots 4 around the perimeter of the screen 3, Fig.1-3. However, it is more rational to use the option with a slit 4 at the bottom of the screen 3 with the location of its overlapping edges and bent from each other, Figs. 4-6.

The device operates as follows.

When the speaker 2 is operating inside the volume formed by the acoustic screen 3, resonances occur in a collision with the screen. However, they will be of high frequency, because their value is proportional to the distance from speaker 2 to screen 3, and it is minimal. Most of the sound resonant vibrations effectively dampens the sound-absorbing material of the screen 6. Sound waves that are no longer able to cause resonances from the inner surface of the screen 3 exit through a narrow slit 4, which partially damps them and directs them into the housing 1. Here, too, part of the sound waves are damped when collision with the sound-absorbing material of the housing 6, and the other part, having lost a fraction of energy, moves back, flowing around the screen 3, Figs. 1, 2, 4. As a result, only a small part of the attenuated reflected sound waves will fall into the slot 4 .

In an embodiment of the upper element with a concave edge 7, FIG. 2, when sound vibrations reflected from the housing hit it, they slide off the edge of the slit 4 into the concavity bowl, reducing the likelihood of getting into the speaker.

In the embodiment, the location of the slit 4 in the lower part of the acoustic screen 3, Figs. 4, 6, when sound waves reflected from the housing 1 hit the lower bent edge of the slit 8, part of them is quenched by sound-absorbing material 6, part is reflected again to the housing 1, losing a fraction of its energy , and only a small part of the waves enters the slot 4 along a curved path, again weakening at the same time.

Claims (4)

1. An acoustic device comprising a housing with a speaker and an acoustic screen located behind it, characterized in that the acoustic screen is made in the form of a truncated cone covering the entire surface of the speaker, with a transverse slit on the side surface, the base of the acoustic screen is fixed to the perimeter of the housing speaker, and the top is interfaced with the speaker’s magnetic system, the surface of the acoustic screen is made of sound-absorbing material. 2. The acoustic device according to claim 1, characterized in that the transverse slit is made around the perimeter of the acoustic screen and divides it into two elements. 3. The acoustic device according to claim 2, characterized in that the upper element of the acoustic screen associated with the magnetic system of the speaker is made with a concave edge. 4. The acoustic device according to claim 1, characterized in that the transverse slit is located in the lower part of the acoustic screen, its edges are overlapped and smoothly bent from each other, and the lower edge is bent from the speaker.

Images