RU2737225C2 - Dynamic loudspeaker with internal double-cavity resonator - Google Patents

Abstract

FIELD: acoustics.

SUBSTANCE: invention relates to acoustics, particularly to loudspeakers. Dynamic loudspeaker comprises internal resonator, volume of which is formed from below by surface of core end of magnetic system, on the sides – the inner wall of the voice coil frame and from above the round fixed cover connected by the rod support to the core weight of the magnetic system, which forms along its periphery an annular slot with the diffuser surface and is divided by inner membrane into two cavities, acoustically connected by tunnel opening, located in the center of this membrane coaxially with frame. Inner membrane by peripheral diameter is glued to inner surface of voice coil frame in its upper part. Lower cavity of the resonator is acoustically connected to the rear field of DL through gap between voice coil and upper plate of magnetic system, and centering washer. Upper cavity of the resonator is acoustically connected to the frontal DL field through gap between annular surface of peripheral part of cover and diffuser surface. Annular slot is controlled by rotation of rod support in threaded connection with core weight and its height is tuning parameter of sound quality of DL.

EFFECT: high definition and spatiality of sound when the stereo effect is expanded to the entire listening area.

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Description

The invention relates to acoustic engineering, in particular to its use as a loudspeaker with a resonant device in high-quality sound acoustic systems, as well as in radios, televisions and other sound-reproducing equipment.

Acoustics is one of the applied disciplines where resonance phenomena affect all oscillatory processes. They tend to suppress unwanted resonances, while useful ones are used in the form of cavities, channels, cavity resonators, which in combination form complex devices similar to resonant circuits, filters, etc.

Known application IPO 7-007789 A (MATSUSHITA ELEKTRIC IND LTD) 10.01.1995., In which D.G. has a MECHANICAL resonator, providing a decrease in optical vibrations of the diffuser near its resonant frequency, which is set by the weight and shape of 2 suspensions with a hole in the center. The resonator structure is fixed in the upper part of the voice coil frame and is closed from above with a solid dust cap (no hole), i.e. has no sound radiation into the frontal space D.G. in 4 variants of the application. In the 5th version, the dust-proof cap is excluded, but the central hole is removed in the upper suspension to preserve the dust-proof properties, i.e. the absence of contact between the cavity of the resonator and the frontal space is preserved. The claimed effect is a decrease in amplitude oscillations due to the creation of oscillations at specified frequencies.

A closer prototype is the application IPH 11346395 (MATSUSHITA ELEKTRIC) 12/14/1999.

In the claimed design D.G. a Helmholtz-type resonator is installed with a coaxial hole - a neck in a dust-proof cap. The cavity of the resonator is formed by the inner wall of the cap, the walls of the voice coil frame and a solid flat bottom, i.e. it has no acoustic connection with the rear space. The result of the action of the resonator is a decrease in the emissivity of the diffuser in the range of 50-200 Hz. The claimed effect is the creation of a passive radiator that does not create unnecessary radiation due to high-frequency resonance and has an excellent response to the high-level input.

The disadvantages of prototypes are the inability to form the necessary parameters and quality characteristics to achieve natural sounding at the level of the original sound sources. In this regard, improving the design of a dynamic loudspeaker in terms of increasing the naturalness of sound reproduction and sound quality is still an urgent task.

The task is achieved by the fact that in a dynamic loudspeaker containing a rigid frame to which a permanent magnet is attached, a sound-generating diffuser on the upper suspension, a lower centering diaphragm, a voice coil (VC) on the frame, it is proposed to additionally install a resonator, the volume of which is formed by the bottom surface of the core end magnetic system (MS), from the sides - by the inner wall of the voice coil frame and from above by a fixed cover - a convex-shaped cap, connected through a rod support with the core mass by a threaded connection.

The volume of the resonator is divided by an inner membrane into two cavities - lower and upper, acoustically connected by a hole in the center of the diaphragm in the form of a tubular tunnel, coaxial with the frame of the ZK. The membrane is glued along the outer perimeter to the inner wall of the ZK frame in its upper part.

The upper cavity of the resonator is acoustically connected with the frontal space of the DW through an annular slot formed by the perimeter of the cover and the front surface of the diffuser. The height of the slot is adjusted by changing the position of the cover relative to the diffuser by rotating the head of the rod support.

The lower cavity of the resonator is acoustically connected with the back field of D.G. through the gap between the voice coil and the top plate of the magnetic system, and the centering washer.

When the DG operates, the vibrations of the inner membrane form a rear sound field in the lower cavity, and a frontal one in the upper cavity. Through the tunnel hole in the membrane, the fields interact and the resulting sound waves are emitted through the annular slit into the frontal space of the DW, qualitatively affecting the sound reproduced by the dynamic loudspeaker. Acoustic connection of the lower cavity with the rear field D.G. enhances this effect.

The claimed solution is complemented by particular distinctive features that contribute to the achievement of the declared results.

The volume ratio of the cavity cavities is 1 + -0.3.

The ratio of the outer diameter of the inner membrane and the diameter of the tunnel hole is 3-3.5, and the ratio of the tunnel length and hole diameter is 0.5-1.0.

The rod support of the resonator cover has a minimum cross-section that provides the required rigidity, and its movement in the threaded connection with the MC core provides a change in the height of the annular slot 0.05-0.1 from the diameter of the cover. The height of the lid is 0, -0.5 of its diameter.

The diameter of the resonator cover depends on the diameter of the SC frame and is 1.2–1.4 of the size of the latter.

The resonator cover has a circular bend around the perimeter, creating a ring, the surface of which is parallel to the plane of the diffuser adjacent to the slot. The width of this ring is 0.07-0.1 times the diameter of the cap.

The essence of the invention is to embed a new structural element into the design of a dynamic loudspeaker - a two-cavity resonator, the interaction of the radiation of which with the radiation of the main diffuser of the DG led to a qualitative change in the sound of the DG - increasing the clarity, spatiality and naturalness, the manifestation of subtle sound nuances that are not audible in the base DG. These effects are especially noted in choral and orchestral audio recordings over the entire audible frequency range. At the same time, one more qualitative change in sound is clearly manifested - the preservation of the stereo panorama and depth of the sound stage throughout the entire listening area, i.e. full-fledged surround sound is perceived practically at any point. The criticality of the place of installation of the sound speakers and their position in the listening room has also sharply decreased - turning the speakers by +/- 30 ° to their axis practically does not affect the quality of the sound picture.

The claimed invention is shown in

FIG. 1 Dynamic loudspeaker with double cavity resonator.

Reference designator list:

Rigid frame DG 1

Permanent magnet 2

Lower centering diaphragm 3

Sound-generating diffuser 4

Upper suspension 5

Voice coil 6

Voice coil bobbin 7

Core end face MS 8

Inner membrane 9

Tunnel hole membrane 10

Resonator cap-cap 11

Rod support of the resonator cover 12

Peripheral ring of the resonator cover 13

Annular slot of resonator 14

Threaded connection of the rod support of the cover and the core MC 15

Rear cavity of resonator A

The frontal cavity of the resonator B.

The inventive dynamic loudspeaker includes a rigid frame 1, to which a permanent magnet 2 is attached, a lower centering diaphragm 3, a sound-generating diffuser 4 on the upper suspension 5 and a voice coil 6 fixed on the frame 7. The DG additionally contains a resonator representing a volume formed by the bottom surface of the end core 8 of the magnetic system (MS), from the sides - the inner wall of the frame 7 of the voice coil and from above with a fixed cap 11 of a convex shape, connected through a rod support 12 with the mass of the core by a threaded connection 15.

The volume of the resonator is divided by the inner membrane 9 into two cavities - A (lower) and B (upper), acoustically connected by a hole 10 in the center of the membrane in the form of a tubular tunnel, coaxial with the frame of the ZK. The volume of cavity A is determined by the inner diameter of the frame 7 ZK and the height of the plane of the inner membrane 10 above the plane of the end of the core 8 MC, and cavity B is determined by the diameter of the cap 11 and the size of its convexity.

Membrane 9 has the shape of a truncated cone to enhance rigidity and is glued along the outer perimeter to the inner wall of the ZK frame in its upper part. By changing the place of gluing and truncation of the cone up and down, the ratio of the volumes of cavities A and B is regulated.

The upper cavity of the resonator B is acoustically connected to the frontal space of the DG through the annular slot 14 formed by the perimeter of the cover 13 and the front surface of the diffuser 4 of the DG. The height of the slot is adjusted by changing the position of the cover relative to the diffuser by rotating the head of the rod support 12.

When the DG operates, the vibrations of the inner membrane 9 form a rear sound field in cavity A, and a frontal one in cavity B. Through the tunnel hole 10 in the membrane, the fields interact and the resulting sound waves are emitted through the annular slot 14 into the frontal space of the DW, qualitatively influencing the sound reproduced by the dynamic loudspeaker.

To optimize the sound quality of the DG, the volumes of cavities A and B, as well as the size of the hole cross-section and the length of the inner membrane tunnel, are structurally determined, and the height of the outlet slot is set during the final adjustment.

The inner surfaces of all elements of the resonator have a high reflectivity of sound waves. The resonator cover has a mass that excludes its vibration from the vibrations of the diaphragm and the sound waves of the DW.

Thus, a DG with a double-cavity resonator, due to the interaction of sound waves of the diffuser and the resonator, acquires new qualitative characteristics of the directivity of their radiation, which provides a better and more natural sound and expands the stereo effect to the entire listening area. The use of such DGs in acoustic systems fundamentally changes and simplifies the conditions for obtaining high-quality sound reproduction in domestic and concert rooms.

Claims (7)

1. A dynamic loudspeaker containing a rigid frame to which a permanent magnet is attached, a sound-generating diffuser on the upper suspension with a voice coil on the frame, a lower centering diaphragm, characterized in that it additionally contains a resonator, the volume of which is formed from below by the surface of the end of the core of the magnetic system, with sides - by the inner wall of the voice coil frame (ZK) and from the top by a round fixed cover connected by a rod support with the core mass of the magnetic system (MS), and divided by an inner diaphragm with a coaxial tunnel hole into lower A and upper B cavities, acoustically connected, respectively, with the rear and front space of the loudspeaker. 2. A dynamic loudspeaker according to claim 1, characterized in that the ratio of the volumes of the cavities of the resonator A and B is 1 + -0.3. 3. A dynamic loudspeaker according to claim 1, characterized in that the ratio of the outer diameter of the inner membrane and the diameter of the tunnel hole is 3-3.5, and the ratio of the length of the tunnel and the diameter of the hole is 0.5-1.0. 4. A dynamic loudspeaker according to claim 1, characterized in that the rod support of the resonator cover has a minimum cross-section that provides the required rigidity, and its movement in the threaded connection with the MC core provides a change in the height of the annular slot 0.05-0.1 from the diameter of the cover. 5. A dynamic loudspeaker according to claim 1, characterized in that the resonator cover has a convex shape, which provides it with a height of 0.2-0.5 of its diameter and determines the volume of the upper cavity of the resonator. 6. A dynamic loudspeaker according to claim 1, characterized in that the diameter of the cover depends on the diameter of the frame of the ZK and is 1.2-1.4 of the value of the latter. 7. A dynamic loudspeaker according to claim 1, characterized in that the resonator cover has a circular bend around the perimeter, creating a ring, the surface of which is parallel to the plane of the diffuser adjacent to the slot, and the width of this ring is 0.07-0.1 of the diameter of the cover.

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