Flat panel loudspeaker

Abstract

The embodiment of the present application relates to the loudspeaker technical field, disclose a kind of flat panel loudspeaker, including support frame, rectangular sound film and the exciter being arranged in the sound film opposite space.Exciter is in the special line that passes along the sound film plane, one of its end portion is attached to sound film, the special line is sent from any vertex of sound film and terminates at the point on the opposite vertex of the horizontal side of sound film, the point is located at the distance of 2 / 3 distance from top in horizontal direction on the opposite side of sound film.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of loudspeakers, in particular to a flat panel loudspeaker. BACKGROUND

[0002] The proposed technical solution is an acoustic wave generator, which can also work as a flat panel loudspeaker of a wide frequency spectrum. The flat panel loudspeaker designed and manufactured in the proposed way is intended to provide a quality advantage for the performance of an acoustic system. This is a flat panel acoustic system with a resonant excitation membrane, which can be used for high-quality reproduction of music and recordings. There are many conventional acoustic devices including cone-type loudspeakers, dome-type loudspeakers and flat panel-type loudspeakers. Such devices have many fundamental drawbacks. One of the most important drawbacks is the volume of the air mass necessary for the operation of such acoustic devices. And this in turn leads to major drawbacks such as phase shift and inconsistency directly dependent on the frequency.

[0003] Since the loudspeaker is a dipole emitter, it is necessary to match the positive phase in front of the loudspeaker with the negative phase behind the loudspeaker.

[0004] This is precisely the reason for using an air-filled casing, which is precisely designed to invert the phase behind the loudspeaker and add it to the front assembly. Thus, we get an acoustic system that is tuned for efficient operation within a certain frequency of the acoustic range. In the case of deviation from the tuning frequency, phase modulation occurs, which introduces spurious harmonics into the distortion of the phase characteristics of the recording reproduction and the modulation causing changes in the amplitude-frequency response of the sound signal.

[0005] It is known that attempts have been made to create acoustic devices that do not have these drawbacks. Among them, flat panel-type loudspeakers based on the operating principle of a resonant sound-emitting membrane occupy a special place. Such acoustic devices do not require any casing and have the feature of a dipole audio signal generation mode (i.e. essentially in-phase in both directions from the membrane). Based on experience, a number of design parameters have been established that directly affect the useful quality of such types of acoustic devices. Such parameters are indicated in Russian and international patents. Among them are the importance of the proportional ratio of the width to height of the membrane, the point of attachment of the acoustic exciter, the membrane attachment method, the type of actuator used, the design of the frame or casing, the possible ways of calibrating the amplitude-frequency response of the acoustic system and other design features.

[0006] The recommended techniques and methods differ greatly in different patents. When trying to put them into practice, we face many difficulties in ensuring the required sound quality. The fact that the above-mentioned design features are all closely related to each other is not stated and is ignored. It is impossible to change one parameter without affecting another, which in turn affects another, and so on. In general, the design features stated in many patents are more likely to be potentially feasible rather than practically applicable, that is, it all comes down to the possibility of trying this or that combination, using this or that proportion, but no one knows which of them will generate a useful acoustic effect, as it is completely determined by reasonable practicality.

[0007] It is known that in loudspeakers, sound-emitting membranes of various designs are used. For example, the patent WO95 / 31805 proposes to use a plastic element of a flat case as a sound-emitting membrane.

[0008] Russian Federation Patent No. 2692096 (stating the properties of the membrane and parameters affecting said properties (for example, the honeycomb structure of such a panel, reinforcing fibers or spacers, and the interweave covering the shell or sheet applied to the core in a specific composite multilayer element, which on each side includes differently oriented or oppositely inclined particles or in the form of several layers on each side)) assumes the use of a membrane with a curved honeycomb structure in space.

[0009] Russian Federation Patent No. 2427100 suggests using glass, wood, or plastic as the membrane body. And the patent US3779336A proposes to mold a granular polystyrene into a membrane. The parameters of all these materials can strongly affect the physical properties of the membrane.

[0010] However, the simple use of these materials to manufacture a membrane without reference to the geometric parameters of the loudspeaker itself will not improve the sound reproduction quality of the loudspeaker system.

[0011] The invention closest to ours is the device stated in the patent US6,332,029 by Henry Azim, December 18, 2001. It states an acoustic device with a flat membrane, which contains at least one acoustic vibration driver installed in space opposite to the special location of the membrane fit, which operates according to the principle of bending resonance modes. Additionally, it provides a favorable proportion of acoustic exciter fit within the panel area. Many individual values are given. For example: 3\7, 4\9 and 5\13, 24 possible combinations are given from each corner. That is, a number of locations for exciter fit are suggested.

[0012] We have found that using such a ratio can not ensure the maximum sound reproduction quality of the acoustic system. SUMMARY

[0013] The technical result is the improvement of the sound reproduction quality of the acoustic system.

[0014] The technical result is achieved by a flat panel loudspeaker comprising a support frame, a sound-emitting membrane fitted to the support frame, and at least one electrodynamic exciter arranged opposite the sound-emitting membrane. In addition, the at least one exciter fits one of the exciter ends to the membrane within a special line passing along the plane of the sound-emitting membrane, the special line emanating from any vertex of the sound-emitting membrane and ending at a point on the opposite vertex of the horizontal side of the sound-emitting membrane, the point being located at a distance of 2 / 3 from the top on the opposite side of the sound-emitting membrane in the horizontal direction; the membrane is made of a honeycomb filler, a surface layer is glued to the honeycomb filler on both sides, and a stable impregnation solution based on polyurethane primer and varnish covers the surface layer.

[0015] In some embodiments, the layer of the stable impregnation solution based on polyurethane primer and varnish is covered with an acrylic polymer layer.

[0016] In some embodiments, the honeycomb filler comprises paper, polyaramid fibers, aluminum, or other metals with a low specific weight.

[0017] In some embodiments, there is also a hem around the perimeter of the sound-emitting membrane.

[0018] In some embodiments, the stiffness of the sound-emitting membrane is uniform in different directions, and the ratio of the long side to the short side of the sound-emitting membrane is 9 / 5.

[0019] In some embodiments, the stiffness of the sound-emitting membrane is non-uniform in different directions, and the ratio of the long side to the short side of the sound-emitting membrane is 9˙k / 5, where k is the ratio of the stiffness in the longitudinal direction to the stiffness in the transverse direction of the sound-emitting membrane.

[0020] In some embodiments, the sound-emitting membrane is fitted to the support frame by a foam tape placed around the perimeter of the sound-emitting membrane. BRIEF DESCRIPTION OF DRAWINGS

[0021] The application is illustrated by the figures.

[0022] Figure 1 is a general view of the flat panel loudspeaker proposed in some embodiments of the application;

[0023] Figure 2 is a schematic view of the main elements of the flat panel loudspeaker proposed in some embodiments of the application;

[0024] Figure 3is a schematic view of the main elements of the flat panel loudspeaker proposed in some embodiments of the present application;

[0025] Figure 4 is a schematic view of the position of the dedicated line in the plane of the sound emitting membrane proposed in some embodiments of the present application, suggesting the placement of at least one or several acoustic exciters in said position;

[0026] Figure 5 is a schematic view of the structural cross-section of the sound emitting membrane proposed in some embodiments of the present application;

[0027] Figure 6 is a schematic view of the position of the multiple exciters in the dedicated line proposed in some embodiments of the present application.

[0028] The reference signs are as follows:

[0029] 1 - sound emitting membrane; 2 - hem of the panel end, made of plastic material;

[0030] 3 - foam tape fixing the sound emitting membrane to the support frame;

[0031] 4 - support frame; 5 - mounting strip; 6, 6.1 - 6.5 - exciters;

[0032] 7 - amplifier connection terminal; 8 - cellular filler; 9 - surface layer;

[0033] 10 - layer of impregnation solution based on polyurethane primer and varnish; 11 - acrylic polymer layer. DETAILED DESCRIPTION

[0034] As a result of extensive practical research, we propose a number of technical solutions that have a direct positive impact on the creation of an acoustic system with outstanding consumer properties. This is implemented in a specific physical device and is a method for applying a technical solution aimed at providing a positive acoustic effect.

[0035] The device consists of a support frame 4 (see Figure 2 ) which should be made of a non-elastic plastic material capable of effectively absorbing vibration energy and strong enough to act as a fulcrum for the bending waves that have reached the edge of the panel (sound emitting membrane 1) from the exciters 6 intended to generate acoustic vibrations and transmit them to the air. On the surface of such a sound emitting membrane 1, zones associated with different ranges of reproducible frequencies are modulated, but these zones themselves are dispersed over the entire area of the sound emitting membrane 1. At least one or several electrodynamic exciters 6 are positioned opposite the sound emitting membrane 1 and have one of their ends fitted to the sound emitting membrane 1 within a dedicated line (see Figure 4 ) passing along the plane of the sound emitting membrane 1. Each exciter 6 is connected to the amplifier connection terminal 7 (see Figure 2 ) by flexible conductive wiring.

[0036] One of the important design parameters that determine the final sound quality of a flat panel loudspeaker system is the aspect ratio of the sound radiating membrane 1.

[0037] That is, the ratio of its long side to its short side. The preferred aspect ratio of such a sound radiating membrane 1 has been determined experimentally to be at least nine parts of the long side to five parts of the short side. The parameters of this ratio can be subject to deviation. If the stiffness of the sound radiating membrane 1 is non-uniform in different directions, in this case the aspect ratio of 9 / 5 must be adjusted by a k factor. The k factor defines the percentage difference between the stiffness in the longitudinal direction of the sound radiating membrane 1 relative to the stiffness in the transverse direction. Thus, if the stiffness is k percent higher in the longitudinal direction than in the transverse direction, the ratio will be 9k\5.

[0038] Another important parameter in the design of a loudspeaker system of this type is the position of the exciter 6 within the area of the sound radiating membrane 1. By way of example, the aforementioned US 6,332,029 patent sets forth a number of preferred mounting ratios for the acoustic exciter 6 within the area of the panel. It represents a number of values. For example: 3\7, 4\9 and 5\13, giving 24 possible combinations from each corner. That is, a number of positions are suggested for the exciter 6 to be fitted.

[0039] We have found that the use of such ratios can not ensure the maximum sound reproduction quality of the acoustic system.

[0040] A large number of practical experiments have constructed a dedicated EB line that passes along the plane of the sound radiating membrane 1 (see Figure 4 ) within which one acoustic exciter 6 or several acoustic exciters 6 should be fitted such that the point of the axis of rotation of the exciter 6 includes the dedicated line or intersects with the front projection of the exciter 6 circuit fitted near the dedicated line. Thus, for a sound radiating membrane 1 with angles denoted by points A, B, C and D, the dedicated line for the exciter 6 to be fitted will pass from point B to point E. In turn, E is a point on the DC side of the sound radiating membrane 1 at which it divides the DC segment in the following ratio: DE \ EC = 1 \2. Within the EB line, one or more exciters 6 can be fitted (see Figure 6 ). For a technical solution with one acoustic exciter 6 within such a line, it is necessary to determine the X point in accordance with the following ratio: EB \ XB = 1.62. In order to use several exciters 6 within such a line, from the point X defined by the fitting point of the first exciter 6.1 (see Figure 6 ), a number of exciters 6.2, 6.3, 6.4 are installed in the direction of point B in such a way that the distance between them is as small as possible. It is also suggested to use acoustic exciters designed to work in the high frequency range, see Figure 6of 6.5. Such an exciter is installed separately from one or more wideband signal exciters, but within the dedicated line EB, preferably close to the corner B.

[0041] Naturally, the dedicated line EB can be reflected symmetrically along any of the symmetry axes of the sound-emitting membrane 1, thus its effect extends equally to the AF line, the DH line and the CG line (see Figure 4 ). Assuming the attachment of the excitation source within the area of the sound-emitting membrane 1, the proposed technical solution in the form of a dedicated line within the area of the sound-emitting membrane 1 has the advantage of ensuring the optimal distribution of the resonant modulation within the area of the sound-emitting membrane 1, which in turn has a positive effect on the uniformity of the amplitude-frequency response; and ensuring the sound naturalness, which is closely related to the reduction of the total amount of distortion, phase shift caused by the operation of the loudspeaker system; and ensuring the maximum frequency range in the operation of such a system.

[0042] Another important parameter directly ensuring good acoustic effect is the sound-emitting membrane 1.

[0043] A large number of practical studies determined the optimal design solution of the sound-emitting resonant sound-emitting membrane 1 (see Figure 5 ). Such a sound-emitting membrane 1 consists of a honeycomb filler 8, which is a honeycomb structure consisting of, for example, various materials: paper, aramid fibers, aluminum or another metal with a low specific gravity. It contains a sheet of surface layer 9 glued on both sides to the honeycomb structure using an adhesive composition that can withstand repeated bending oscillations of the vibrations. It is proposed to use paper 9 with a density of 30 g to 125 g per square meter of area as a covering material. Next, the surface layer 9 is impregnated with a stable impregnation solution based on polyurethane primer and varnish. If necessary, the layer 10 of the stable impregnation solution based on polyurethane primer and varnish is covered with a layer 11 of acrylic polymer (including micron-sized grinding of mineral and organic substances (quartz, walnut shells, rice and rice husks, etc.).

[0044] Figure 5 The layers 10 and 11 in the sound-emitting membrane 1 largely determine the elastoplastic properties of the sound-emitting membrane 1, as well as the final tonal balance of the amplitude-frequency response - a parameter responsible for the reliability of the sound content reproduction. It is also revealed the importance of minimizing the final mass of the finished membrane. This directly affects the sensitivity of the loudspeaker system; under other conditions being equal, the smaller the mass of the sound-emitting membrane 1, the higher the rate of rise of the front edge of the impulse signal.

[0045] The actual density of the completely finished sound-emitting membrane 1 (ranging from 350 g / 1 square meter to 750 g / 1 square meter) has practical value. The sound-emitting membrane 1 also includes edge handling: flanging of the semicircular sponge around the entire perimeter of the sound-emitting membrane 1.

[0046] The rim is made of a material with a relatively high (plastic) specific weight and high level of plasticity, which helps to quickly attenuate oscillations in the thickness of this material. The rim 2 (see Figure 2 ) serves to increase the mass of the edge of the sound-emitting membrane 1 to support the surface-traveling wave emanating from the source of acoustic influence towards the edge of the sound-emitting membrane 1, and effectively reflects this wave in the opposite direction, thus ensuring the modulation zone oscillation mode of the frequency-dependent amplitude pulse.

[0047] In practical applications, the internal structure of the honeycomb filler 8 can be from 3 mm to 7 mm thick. The thickness and stiffness parameters should be related to the absolute size of the sound-emitting membrane 1. The absolute size of the sound-emitting membrane 1 with a specific stiffness is recommended based on the coefficients revealed by experimental studies.

[0048] In addition to the above-mentioned technical solutions, it is necessary to mention the importance of the way the sound-emitting membrane 1 is fixed in the support frame 4 of the acoustic device. This is a key parameter that determines the correct location of the amplitude modulation within the panel area, which in turn completely determines the acoustic properties of the flat panel loudspeaker.

[0049] We have also identified a practically preferred method of gluing the sound-emitting membrane 1 to the support frame 4, which ensures the optimal distribution of the zone of increased amplitude frequency modulation on its surface. It is a semi-open type of gluing, where the foam tape 3 is mounted along the entire perimeter to one side of the sound-emitting membrane 1, which in turn most often is a 10 mm gap between the sound-emitting membrane 1 and the support frame 4. This foam tape 3 holds the ends of the sound-emitting membrane 1 to provide the required support mass (as well as the edging of the membrane ends using plastic material), from the interference of the primary wave, which will form zones of increased amplitude within the panel, which is crucial for the effective operation of the acoustic system itself. The semi-open type of gluing helps to effectively exploit the other functions of the foam rubber, namely to provide acoustic isolation between the sound-emitting membrane 1 and the support frame 4, which greatly affects the sound quality, reducing harmonic distortion in the process of generating acoustic signals.

[0050] The proposed technical solution allows to achieve a significant improvement in the quality characteristics of the loudspeaker system in one sound-emitting membrane 1 with less labor and material costs. At the same time, the use of a minimum number of acoustic pathogens can significantly improve the quality, saving money and materials.

[0051] The application of the design method and technical solutions set forth in our patent can create a full-range loudspeaker system. In practice, this means that a compact (flat) device can produce the entire sound spectrum audible to the human ear within the range from 20 Hz to 20,000 Hz. And when we can talk about the implementation of the highest class of acoustics in practice, the level of harmonic distortion is reduced to a minimum.

[0052] This is largely due to the above-mentioned technical solutions, which are designed to control the process of correct distribution of the frequency-dependent pulse area of the vibration amplitude over the area of the sound-producing membrane 1. Their correct distribution (reflected in the frequency response as the line with the least deviation from the straight line) implements such a useful acoustic effect, i.e. reduction of the "doppler effect" of sound production in a wide range. This harmful phenomenon is characterized by distortion for the listener, which is caused by the fact that when one speaker simultaneously produces different frequencies, the low frequencies of higher amplitude become carriers of higher frequencies with lower amplitude. Thus, the high frequency components in turn approach and move away from the listener, causing the "vibrato" effect (a form of distortion in the form of sound tremor).

Claims

1. A flat panel loudspeaker comprising a support frame, a rectangular sound producing membrane attached to the support frame, and at least one electrodynamic exciter disposed opposite the sound producing membrane, characterized in that, The at least one electrically driven exciter adheres one of the exciter ends to the sound emitting membrane in a dedicated line passing along the plane of the sound emitting membrane, the dedicated line emanating from any one of the vertices of the sound emitting membrane and ending at a point on the side of the sound emitting membrane opposite the vertex, the point being located at a distance of 2 / 3 of the horizontal distance from the vertex on the opposite side of the sound emitting membrane; the sound emitting membrane is made of a honeycomb filler, a surface layer glued to the honeycomb filler on both sides, and a stable impregnation solution based on polyurethane primer and varnish covering the surface layer, wherein the surface layer is paper with a density of 30 to 125 g per square meter of area.

2. The flat panel loudspeaker of claim 1, wherein, The layer of the stable impregnation solution based on polyurethane primer and varnish is covered with a layer of acrylic polymer.

3. The flat panel loudspeaker of claim 1, wherein, The honeycomb filler comprises paper, polyaramid fibers, aluminum or other metals with low specific gravity.

4. The flat panel loudspeaker of claim 1, wherein, It also comprises a hem around the perimeter of the sound emitting membrane.

5. The flat panel loudspeaker of claim 1, wherein, The stiffness of the sound emitting membrane is uniform in different directions, and the ratio of the long side to the short side of the sound emitting membrane is 9 / 5.

6. The flat panel loudspeaker of claim 1, wherein, The stiffness of the sound emitting membrane is non-uniform in different directions, and the ratio of the long side to the short side of the sound emitting membrane is 9*k / 5, where k is the ratio of the stiffness in the longitudinal direction to the stiffness in the transverse direction of the sound emitting membrane.

7. The flat panel loudspeaker of claim 1, wherein, The sound emitting membrane is adhered to the support frame by a foam tape placed around the perimeter of the sound emitting membrane.

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