RU2744773C1 - Acoustic installation for the emission of a transverse sound wave in a gas environment - Google Patents

Abstract

FIELD: acoustics.

SUBSTANCE: invention relates to acoustics. An acoustic installation for the emission of a transverse sound wave in a gaseous medium contains a housing, a flat membrane, a drive for acoustic vibrations of a transverse acoustic wave. In this case, the housing is made in the form of a support frame, and a sound-emitting flat rectangular membrane is fixed on the frame. The membrane is made in the form of a honeycomb filler, a surface layer glued to the honeycomb structure on both sides and a stabilizing impregnating composition based on polyurethane primers and varnishes, covering the surface layers. The drive of acoustic vibrations is made in the form of an acoustic vibration exciter including ferrite parts of the magnetic circuit. The exciter of acoustic vibrations is attached at one end to a flat membrane within a special line passing along the plane of a rectangular membrane and emerging from any vertex of a rectangular membrane, and ending at a point on the opposite vertex of the horizontal side of the membrane, located at a distance of 2/3 of the opposite side of the membrane from the vertex horizontally.

EFFECT: technical result is an increase in the effective operation of an acoustic installation for radiation of a transverse wave, an expansion of the operating frequency range, an increase in the efficiency of generating a low-frequency signal with a transverse component of an acoustic wave.

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Description

The invention is applicable in acoustics. It can be used as a loudspeaker for consumer purposes, in which the principle of its operation is based on the ability of resonant excitation of bending antiphase vibrations, followed by the emission of transverse acoustic waves into the air (a type of wave process in which shear vibrations of molecules occur perpendicular to the direction of wave propagation).

State of the art

From the article (http://selftrans.narod.ru/v2_1/acoustics03/acoustics3rus.html) S. B. Karavashkin and O. N. Karavashkina (see page 4), it is known that for the excitation of a transverse wave in a gaseous medium, it is sufficient that the source of its excitation is two antiphase emitting acoustic membranes.

Also from the prior art, a number of devices can be distinguished theoretically capable of generating transverse acoustic waves. This is a number of well-known musical instruments, such as an acoustic guitar, grand piano, drum, violin, etc., in which the resonator body or membrane (in the case of a drum) acts as a key element that forms a transverse sound wave. the task was to ensure efficient generation of transverse-wave radiation in a wide spectrum of frequencies and with specified parameters of signal characteristics. Thus, their ability to emit sound with a transverse wave component is rather random, and the impossibility of actually adjusting the radiation parameters makes them unsuitable for use in our proposed field of technology.

The closest technical solution can be considered a universal speaker, disclosed in the patent of the Russian Federation No. 2692096 dated 06/21/2019. This speaker contains a flat diaphragm, an excitation unit, a housing that forms a cavity in which the diaphragm and an excitation unit are located. The housing has a hole on one surface, and the excitation unit abuts against the end edge of the membrane so that it is excited in the same direction as the direction of the membrane plane, and is also rigidly mounted on the housing. The diaphragm forms a curved portion that curves from the side of one end where the driver is mounted to the opposite side of the other end, and is positioned to cover the opening of the housing. The disadvantage of this solution is insufficient work efficiency.

The tasks that the proposed invention solves:

- increasing the effective operation of the acoustic installation for transverse wave radiation,

- expansion of the working frequency range to the limits of audibility of 20-20000 Hz,

- providing the ability to control the processes of wave generation in a wide range, compacting the device, compared with an analogue, rejecting high-voltage elements (10-30 kV) in the device circuit,

- increasing the efficiency of generating a low-frequency signal with a transverse component of the acoustic wave.

The technical result is an increase in the effective operation of an acoustic installation for radiation of a transverse wave, an expansion of the operating frequency range, an increase in the efficiency of generating a low-frequency signal with a transverse component of an acoustic wave.

The technical result is achieved by the fact that the acoustic installation for radiation of a transverse sound wave in a gas medium includes: a housing, a flat membrane and a drive for acoustic vibrations of a transverse acoustic wave.

In this case, the body is made in the form of a support frame, and a sound-emitting flat rectangular membrane is fixed on the frame, the membrane is made in the form of a honeycomb filler, a surface layer glued to the honeycomb structure on both sides and a stabilizing impregnating composition based on polyurethane soils and varnishes covering the surface layers, the drive of acoustic vibrations is made in the form of at least one exciter of acoustic vibrations, including ferrite parts of the magnetic circuit, and at least one exciter of acoustic vibrations is attached at one end to a flat membrane within a special line passing along the plane of the rectangular membrane and coming out of any vertex of a rectangular membrane, but ending at a point on the opposite vertex of the horizontal side of the membrane, located at a distance of 2/3 of the opposite side of the membrane from the vertex horizontally.

The proposed invention makes it possible to design and implement a compact effective device in areas where it is required to create transverse-wave acoustic radiation in a gaseous environment, not only for the purpose of studying the properties of such radiation, but also for its practical use, for example, in the form of a loudspeaker with improved sound quality.

Brief Description of Drawings

FIG. 1 is a general diagram of a device that emits a transverse acoustic wave in a gaseous medium, indicating all the main elements,

FIG. 2 is a rear view of a device emitting a transverse acoustic wave in a gas environment,

FIG. 3 is a schematic representation of the conditions for the occurrence of a transverse acoustic wave in a gas medium,

FIG. 4 - external view of the device emitting a transverse acoustic wave,

FIG. 5 - the position of a special (orange) line within the plane of the sound-emitting membrane, on which the placement of at least one or several acoustic vibration exciters is recommended.

The device proposed by us for the emission of a transverse acoustic wave (Fig. 1) includes: a support frame (1), a sound-emitting membrane (2), an acoustic vibration drive (3), including parts of a ferrite magnetic circuit, as well as a coil of different types proposed: flat, square (rectangular), wavelike flat, cylindrical (round), star-shaped, back cover-support for the drive (4).

For example, the acoustic vibration drive (3) includes one (or more) acoustic vibration exciter containing a housing in which are installed: a magnetic system, a cylindrical coil fixed to the frame, a coil holding system within the magnetic gap and flexible wires for supplying an electrical signal to coil. In this case, the magnetic system is made in the form of a permanent magnet of a cylindrical shape, a ferrite ring, in the center of which there is a specified cylindrical magnet and washers fastening them into a single structure, a cylindrical coil fixed on the frame is located above the cylindrical magnet and in the gap between the cylindrical magnet shape and a ferrite ring, the coil holding system within the magnetic gap consists of two centering washers of different diameters fixed at some distance from each other, in the form of concentrically corrugated disks, with an inner hole attached to a cylindrical coil attached to the frame, and an outer perimeter to the body , in this case, flexible wires supplying an electrical signal to the coil are sewn into one of the centering washers and are soldered at one end to the terminals of the coil, and at the other to the outer contact group. The barrel coil frame is attached to the sound emitting membrane (2).

The sound-emitting membrane (2) is made of a light and rigid material - a sandwich structure, including a honeycomb filler, a surface layer glued to the honeycomb structure on both sides and a stabilizing impregnating composition based on polyurethane primers and varnishes, covering the surface layers.

Such a membrane (2) begins to conduct traveling wave structures formed by a drive of acoustic vibrations (3) applied to the surface of the membrane along the surface. Surface traveling waves having a finite propagation velocity in the membrane material repeatedly re-reflecting from the edges of the membrane itself form resonance-conditioned, frequency-dependent modulations, zonally localized over the area of the panel. These modulations have one distinctive feature: they arise in the form of strictly opposite balanced vibrations within one indivisible sound-emitting membrane (2).

For ease of understanding, these opposite bending vibrations can be represented as a set of incoherent point acoustic emitters (speakers), strictly out of phase at 180 degrees, see Fig. 3. This mode of operation of the proposed acoustic emitter is the main and necessary, since in modes that go beyond the resonant balanced formation of opposed modulations, the process of effective generation of the sound signal as such stops, and the conditions necessary for the formation of the transverse component of the wave do not arise.

Also, as a result of numerous practical experiments, a special line EB was established (see Fig. 5) extending along the surface of the sound-emitting membrane, within which the exciter or exciters of acoustic vibrations should be installed so that the point of the axis of rotation of the exciter includes a special line, or intersects the frontal a projection of the pathogen circuit installed near the special line. So if we take into consideration a sound-emitting membrane, the corners of which represent points A B C and D (see Fig. 5), then a special "orange" line of attachment of the pathogens will pass from point B to point E. In turn, E is such a point on the DC side of the membrane in which it will divide the DC segment in the proportion: DE \ EC = 1 \ 2. Within the EB line, at least one source of excitation of oscillations, as well as several such sources, can be installed. In the case of applying a technical solution with one source of excitation of acoustic vibrations within which line, point X should be determined, which is determined according to the following proportion: EB \ XB = 1.62. Naturally, the orange line EB can be symmetrically reflected along any axis of symmetry of the membrane.

The advantage of our proposed technical solution in the form of a special line within the membrane area, suggesting the attachment of excitation sources within it, is to ensure the optimal distribution of resonant modulations within the membrane area, which in turn has a positive effect on the uniformity of the amplitude-frequency characteristic, as well as ensuring such parameter, as the naturalness of sound, closely related to the total amount of distortions introduced by the operation of the speaker system, the reduction of phase shifts, as well as ensuring the maximum frequency range in the operation of such a system.

In our acoustic device, special measures are not required to maintain the condition for the existence of a transverse sound wave. The very resonant mode of operation of such a device assumes the constant presence of suitable conditions for the emergence and maintenance of a shear wave. Moreover, these conditions exist as a continuous readiness of the transverse wave radiation in the gas at practically any frequency of the acoustic range, including wider limits in the region of low and high frequencies, if necessary. So to implement radiation with a transverse component, it is enough to bring one single excitation source to the emitter, powered by a single-channel power amplifier and apply the appropriate signal (for example, sinusoidal, of a certain frequency, or broadband ("pink noise", music content, etc.))

The external view of the proposed acoustic installation for the emission of a transverse sound wave in a gaseous medium is shown in Fig. four.

At the same time, it is important to emphasize the fundamental impossibility of high-quality generation of a transverse acoustic wave at the Karavashkins installation while simultaneously supplying it with signals of different frequencies and amplitudes. This is due to the fact that the formation of all frequencies by one piston emitter causes the acoustic Doppler effect. This unambiguously leads to the impossibility of maintaining phase consistency in the entire range of simultaneously applied frequencies.

In the case of our construct (the membrane is made of a cellular material and a certain location on the membrane of the exciter of acoustic vibrations), when the frequency modulations are zoned over the area of the panel, the lower frequency is not the carrier for the higher ones and the Doppler effect does not occur. Thus, only such a solution makes it possible to continuously generate and maintain a transverse acoustic wave in the gas in the entire spectrum of simultaneously applied frequencies and to obtain the claimed technical result.

Claims (1)

Acoustic installation for the emission of a transverse sound wave in a gas environment, including a housing, a flat membrane, a drive for acoustic vibrations of a transverse acoustic wave, characterized in that the housing is made in the form of a support frame, and a sound-emitting flat rectangular membrane is fixed on the frame, the membrane is made in the form of a honeycomb filler , a surface layer glued to the honeycomb structure on both sides and a stabilizing impregnating composition based on polyurethane soils and varnishes, covering the surface layers, the acoustic vibration drive is made in the form of at least one acoustic vibration exciter including ferrite parts of the magnetic circuit, and at least at least one acoustic vibration exciter is attached at one end to a flat membrane within a line passing along the plane of a rectangular membrane and emerging from any vertex of a rectangular membrane, and ending at a point on the opposite apex of the horizontal side of the membrane, located at a distance of 2/3 of the opposite side of the membrane from the apex horizontally.

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