MXPA00002783A - Miniature full range loudspeaker - Google Patents

Abstract

In a miniature loudspeaker (10) of the electromagnetic voice coil type with a stiff edge-driven concave diaphragm (16), a single suspension member (18) attached to a particular location on the voice coil form (26A) achieves high excursion performance to deliver a full audio range in a cylindrical package of minimal thickness and diameter suitable for sound systems of compact multi-media equipment including PC CRT monitors and flat displays as in lap top computers. The front end of the tubular voice coil form is attached to the perimeter of the diaphragm. The front end of the tubular voice coil form is attached to the perimeter of the diaphragm. The coaxial voice-coil-diaphragm assembly is supported by a single resilient surround suspension member with its inner edge attached around the voice coil form at a location that is offset slightly from the front end of the voice coil form.

Description

MINIATURE LOUDSPEAKER OF COMPLETE RANGE PRIORITY The benefit is claimed in accordance with 35 USC, paragraph 119 (e) of pending provisional application 60 / 093,600 filed on July 21, 1998. FIELD OF THE INVENTION The present invention relates to the field of loudspeakers and more specifically refers to to the new configuration of a full-scale miniature loudspeaker that is especially suitable for use in restricted-space multimedia applications. BACKGROUND OF THE INVENTION In the design of miniature loudspeakers, the smaller size generally implies a trade-off related to the low frequency response, since for a given acoustic intensity, while the frequency decreases, the loudspeaker acting as a piston "pumps" a larger volume of air, this displacement volume being basically the product of the area of the diaphragm and the amplitude of its vibratory excursion, which is always subject to a physical supply for the assembly of the loudspeaker. While the response range of the loudspeaker frequency can be extended to decrease the frequencies, by applying low reflection techniques in the attached design, the displacement volume will still act to set limits on the total low frequency performance. In the category of electromagnetic loudspeakers of coil type or coaxial round coil directed by the present invention, as can be seen, for example of the type of cornet type transducers, there are 2 basic types of assembly: (1) The conventional type of dual suspension full range, where the diaphragm is formed as a cone that is substantially larger in diameter than the mobile coil shape and where 2 suspension members are deployed: A "peripheral" suspension member on the outer edge of the cone extending to a frame / frame region and a "spider" in the form of a moving coil that extends to a nearby platform formed by the frame / frame, and (2) Speakers with limited frequency range and edge driven diaphragm, where the diaphragm and the mobile coil shape are made of the same diameter, the outer edge of the diaphragm is attached to the end of the movable coil shape and also to a suspension member. simple peripheral, which extends outwardly towards a platform attached to the frame / frame. Said assembly is conventionally used for "tweeters" (high-boost loudspeakers), where a rigid dome diaphragm is commonly used and sometimes for "mid-range" loudspeakers; The missing bass frequency response is covered by the use of a "woofer" unit (subwoofer) separately in a 2-way or 3-way speaker system. The suspension system is of key importance, since it must allow a maximum required amplitude of vibration while restricting the vibratory movement essentially towards a straight line path, avoiding any contact of the moving coil or its shape with the structure of the magnetic pole that it surrounds it. The peripheral suspension member is required to prevent any inclination, undulation or other external vibration in the diaphragm while allowing the desired total vibration and possibly damping against settling. A generally unrecognizable problem in the small speakers that have been addressed by the present invention involves spurious vibration of the portions of the condescending peripheral suspension member in high frequency and in other directions in addition to the desired main axial direction. These spurious vibrations can be transmitted to the diaphragm where it is attached directly to the peripheral suspension member as in conventional practice, thereby degrading the high frequency performance. The present invention addresses the challenge of developing a new loudspeaker assembly that provides the full-range response, hitherto limited to type (1) above while obtaining the advantages and volumetric benefits of the boom-driven type (2) and decreasing its disadvantages, in a manufactured product that is particularly suitable for use in conjunction with space-restricted multimedia audio systems. DISCUSSION OF THE RELATED KNOWN TECHNIQUE U.S. Patent 5,181,253 to Jordan, assigned to Southern Audio Services, discloses an edge driven dome diaphragm supported by a peripheral suspension member attached to the leading edge of the moving coil. U.S. Patent 5,157,731 of Mitobe, assigned to Pioneer, presents an acoustic dome radiator screen, where the diameter of the moving coil matches the diameter of the dome; however, the dome, the mobile coil shape, configured as a channel, and the peripheral suspension are formed integrally of a sheet of the material. The permanent magnet is an external donut type. United States patents 4,031,337 and 3,780,232 also show edge driven dome diaphragms. The above references are typified for high-boost loudspeakers with dome diaphragms that attempt to operate only in a high audio frequency range greater than 500 Hz as distinguished from the total range addressed in the present invention, which extends to less than 100 Hz. US Pat. No. 3,983,337 to Babb illustrates a 1976 attempt at a miniature wide-band horn with a reinforced cone extending beyond the diameter of the moving coil, however it is of great interest when discussing the limitations Theories that are faced when developing full-scale miniature speakers. The United States Patent 4,384,174 of Susuki et al, assigned to Victor is of great interest by using only a single conventional suspension member together with a new viscous O-ring support at the periphery of the cone, which extends beyond of the diameter of the moving coil. U.S. Patent 5,739,480 to Lin has a horn base for alternately mounting different conductors. A conventional bass-enhancing speaker assembly with a first-edge suspension member attached around the perimeter of the tapered diaphragm and a second suspension member attached around the moving-coil form is shown, the diaphragm extends internally only towards the region of the perimeter link of the movable coil shape, then leaving a large circular central opening with a diameter approaching that of the movable coil shape that is provided for installing a low-booster loudspeaker diffuser or booster loudspeaker driver high on a driver's base, surrounded by the mobile coil shape. OBJECTIVES OF THE INVENTION It is a main objective of the present invention to provide a miniature electromagnetic speaker with full-range audio capability. Another goal is for the speaker to be appropriate for the audio needs and requirements of multimedia computers, particularly laptop computers. A further goal is to make the assembly speaker simple that can be produced in series and at low cost. It is also your goal to set the speaker with a simple suspension element. SUMMARY OF THE INVENTION The aforementioned objectives have been achieved by the present invention of a miniature loudspeaker of electromagnetic type of mobile coil wherein the diaphragm is concave, as can be seen from the diaphragms of loudspeakers reinforced high peripherals that are known and it extends only to a size equal to the diameter of the mobile coil shape to which it is attached. The resulting bobbin or driven edge diaphragm assembly is supported by a simple peripheral suspension member attached to the tubular moving coil form at a location therein that separates a predetermined distance along the moving coil form from its point end of the link to the diaphragm. The magnetic system has a coaxial structure: A thin vessel acts as a pole piece enclosing a permanent cylindrical magnet and a circular internal pole formation with the edge of the vessel, an annular magnetic air gap where the moving coil, driven by the audio current vibrates axially and at the same time drives the mobile coil shape and the diaphragm. This moving coil or vibrating diaphragm assembly is supported by means of a peripheral suspension member that is peripherally connected to a plastic mounting ring that surrounds it and is attached to the container and linked in its internal diameter to the outside of the shape of mobile coil in the place that is separated from the diaphragm junction. Structural features include the concave edge driven cone, the magnetic interval geometry and the special deployment of the simple peripheral suspension member, in particular, its special connection in the form of a mobile coil instead of the conventional practice of joining it directly to the edge of the diaphragm is combined to generally allow a large amplitude of vibration, thus allowing the miniature speaker to function as a loudspeaker Full audio range that provides an acoustic output at low frequencies up to 100 Hz when deployed along with a low-reflective loudspeaker. Furthermore, this special joint benefits the high frequency performance by isolating the diaphragm from the influence of high frequency spurious vibrations of the parts of the peripheral suspension member in other directions in addition to the desired axial direction, particularly the radial directions. It is tried to use the loudspeaker with computer monitors of both the CRT type and the flat image type as used in laptop computers; it is equipped with articulated devices that allow the assembly in the form of a spring to a part of the acoustic screen of an acoustic box. BRIEF DESCRIPTION OF THE DRAWINGS The aforementioned objects as well as other objects, features and advantages of the present invention will be more fully understood from the following description taken with the attached drawings, in which: FIG. 1 is a front view of a loudspeaker of the present invention. FIG. 2 is a side view of the speaker of FIG. 1. FIG. 3 is a central cross section of the speaker of FIG. 2.

FIG. 4 is a rear view of the speaker of FIGURES 1 and 2. FIG. 5 is an enlarged view of the circulated part of FIG. 3. FIG. 6 is an elongated three-dimensional view of the loudspeaker of FIGURES 1, 2 and 4, viewed from a rear region. DETAILED DESCRIPTION FIG. 1 represents in a front view, a full-scale miniature loudspeaker 10 of the present invention, having a mounting ring 12 defining a circular perimeter from which a pair of wires for connections 14, which extend outwardly, is shown. The circular diaphragm 16 is supported by a peripheral suspension member 18 peripherally attached to the mounting ring 12. FIG. 2, a side view of the speaker of FIG. 1, shows the loudspeaker 10 with the peripheral suspension member 18 extending upwardly from the mounting ring 12. A coaxial metallic container 20 formed downwardly, engaged by the mounting ring 12 which is formed to have a polar arrangement of reinforcing blocks 12A that extend downward and push against the wall of the container 20. Mounting ring 12, commonly molded from plastic, is configured with arrays of articulated fastening members by means of which the loudspeaker 10 can mounted as a spring to an acoustic screen.

FIG. 3, a central cross section from the same point of view as FIG. 2, shows a container 20 constituting a minor pole piece of a permanent cylindrical magnet 22, fitted at its opposite upper pole with a disc-shaped pole piece 24 extending to cover the inner side of the upper flange of the container 20, forming then the annular magnetic air gap of the speaker. A form of mobile coil 26A, wound with a moving coil deployed in the magnetic air gap, which extends upwards to where it joins the perimeter of the diaphragm 06, which as seen has a concave shape. The movable coil assembly with the diaphragm is held in place by a peripheral suspension member 18. NOTE: in FIGS. 2, 3 and 5, the loudspeaker 10 pointing upwards is shown; it should be understood that this upward direction is actually the forward direction of the loudspeaker 10, and in the same way the downward direction as shown, is actually the backward direction of the loudspeaker 10. FIG. 4, a rear view of the speaker 10 showing the mounting ring 12 configured with six reinforcing blocks 12A accommodated around the container 20. Two wires for connections 14 extend outwardly. The mounting ring 12 is also configured with four mounting groups 12B by means of which the speaker 10 can be mounted in the form of a spring in an acoustic screen. FIG. 5 an elongated view of a circular region of FIG. 3 showing a moving coil 26B in the magnetic air gap between the upper pole piece 24 and the inner flange of the container 20 forming the opposite pole piece. The upper rim of the movable coil shape 26A is adhesively bonded to the lower side of a flat narrow flange that is formed around the edge of the concave diaphragm 16. The inner edge of the flexible peripheral suspension member 18, which may include a short flange as shown, adhesively attaches to the shape of moving coil 26A in a location that is somehow below its upper end, while its outer edge is joined by means of the outer flange on a flat annular surface with forward-facing suspension connection on the front side of the mounting ring 12, which is shown in the upper region of the reinforcing block 12A. The structure is provided, for a generally large excursion range, for the mobile coil assembly with the diaphragm, which includes a moving coil 26B, moving coil form 26A, diaphragm 16 and peripheral suspension member 18, improving the capabilities low frequency speaker 10, so that it can function as a full-range unit. The cross-sectional shape of the peripheral suspension member 18 shows the arcuate portion extending upward toward a front plane of the loudspeaker 10, as defined by the perimeter of the diaphragm 16. FIG. 6 is an elongated three-dimensional view of the speaker 10 as viewed from the rear location, showing the mounting ring 12 with reinforcing blocks 12A accommodated around the container 20, from which the two wires for connections 14 extending to outside. These are connected through integrated flat conductors 28 to the moving coil, thus eliminating a conventional two-terminal board and mounting rivet. There is a total of six reinforcing blocks 12a (refer to FIG 4) arranged in a polar network around the container 10, each one is adjusted against the wall of the container 20, where these can optionally be fixed adhesively or any other. It is configured in a mounting ring of four places 12 with a mounting group 12B, which includes a locking flap in the form of a flag 12C and a pole with a rotation stop 12D, which serves to provide the spring connection to a screen acoustic of a sound box, commonly a system of reflection of basses. The acoustic screen is configured with a circular dimensional aperture to a peripheral suspension member 18, so that the speaker 10 can be mounted on the back side of the acoustic screen; four cantilevered arms on the acoustic screen engage the mounting groups 12B. The mounting ring 12 is formed to provide a stepped mounting band 12E between each pair of adjacent blocks 12A to further facilitate spring mounting. When the loudspeaker is placed in front of the rear acoustic screen, the outer flange of the peripheral suspension member 18 functions as a shutter, eliminating the need to provide a separate shutter, as required in conventional mounting practice. A plurality of openings are provided around the wall of the container 20 between the reinforcements 12A to allow acoustic ventilation, so that the acoustic pressure from the back of the diaphragm 16 can be communicated to the interior of the box system, commonly reflective. low. The invention may also be put into practice with variations of the preferred embodiment described above without departing from the spirit of the invention. The permanent magnet can be made in the form of a donut with a cylindrical central body associated with the disc-shaped pole piece 24, while the other pole piece would be formed simply as a cylindrical collar; this would suffer from the magnetic field leakage, which in the previous embodiment is contained by the container 18 and which can be detrimental to use the loudspeaker for computer service and / or may require the additional expense of magnetic shielding. The permanent magnet 22 may be of any known magnetic material that is commonly used in loudspeakers; the polar pieces (container 18 and disc 16) are commonly made of steel or magnetically sweet iron, but can be made of another material suitable for their magnetic function as polar pieces. The diaphragm 16 can be made of any suitable material that provides stiffness and light weight; metals such as titanium or aluminum or non-metals such as plastic or impregnated or reinforced paper. The concave shape of the diaphragm 16 serves to reduce the speaker height so as to provide a low profile package total. Functionally, the invention can be practiced in a less preferred way with a diaphragm 16 made in a convex shape; alternatively this could be done flat, but that would make it more difficult to obtain the desired stiffness with a sheet of lightweight and thin material. As an alternative to the "butt" connection of the diaphragm 16 to the upper end of the movable coil shape 26a shown in FIG. 5, there is an option to form the diaphragm 16 to provide an annular channel with the front facing down that can flank the edge of the moving coil shape 26A, to facilitate locating and holding operations. A preferred embodiment of the speaker 10 has overall dimensions of 31 mm in diameter by 14 mm in depth. The diaphragm 16 is concave for a maximum depth of 2.6 mm. The outer part of the moving coil shape 16A and the concave portion of the diaphragm are 19 mm in diameter. Referring again to FIG. 5, the mobile coil shape 26A is made to extend upwards 4.3 mm, beyond the moving coil 26B. The place designated for the attachment of the peripheral suspension member 18 along the mobile coil shape 26A is chosen to be 1.6mm from the end to cause the front extension of the peripheral suspension member 18 to level with the front plane of the speaker 10, i.e. the perimeter of the diaphragm 16. Suitable material selection of the peripheral suspension member 18 and its clamping place along the free region of the moving coil shape 26A acts to damp and isolate the diaphragm 16 and to ensure that the moving coil 26B is constrained coaxially in the magnetic range while vibrating longitudinally, so that its path is maintained in a straight line free of undulations or any foreign movement.

A key dimension related to the low frequency acoustic intensity capability the clarity allowed for the excursion of the moving coil assembly and the diaphragm; This is done to be 2.55 mm in two potential seating locations: between the lower end of the movable coil form 26a and the bottom of the container 20, and between the lower end of the diaphragm 16 and the upper pole piece 24. Then it is - provides a maximum symmetrical excursion range of 5.1 mm from peak to peak. As a factor of size efficiency, the excursion to the total thickness of the speaker can be compared. For a hypothetical cylindrical speaker of specified diameter with a cone of equal diameter and a peak-to-peak excursion equal to the thickness of the speaker, this factor would be 100%; that is, the volume of the displaced air would equal the volume of the speaker itself. In the embodiment of the present invention described above, this factor is 5.1 mm / 12 mm, that is, 42.5%, compared with commonly less than 10% for conventional speakers. The moving coil 26B is made 2.9 mm long; The spacing of working magnetic air gap is 1.47 mm. The container is made with 1.75 mm thick, the permanent magnet of 3.77 mm thick and the upper pole piece 24 of 1.4 mm thick. The peripheral suspension member 18 is configured and arranged to provide a degree of coercion for the maximum excursions of the moving coil and diaphragm assembly, both at the rising limit, which is not restricted in any other way, and at the lower limit , where it acts to cushion against the settlement. When considering the arched shape of the peripheral suspension member 18, it is considered that the arched shape shown with an arc subverting an angle of 180 degrees or slightly less is optimal, however the invention can be practiced with at least a partial equivalence , using known alternate configurations of the peripheral suspension member, for example, a series of concentric corrugations. The detailed configuration of the mounting ring 12 and the particular method of joining an acoustic screen and the associated housing are not of great importance for the acoustic function of the invention; the variations that may allow the basic practice of the invention in some barter of convenience, for example, conventional mounting with screw tools instead of spring mounting. The spring assembly can also be achieved with alternate configurations and / or with a different number of joint groups besides the four. The spring clamping system can be implemented with metal springs or flexible plastic closing members.

The invention can be put into practice, using a mounting arrangement with torsion closure, which involves rotation of the loudspeaker frame, incorporated together with or as an alternative to the spring assembly. The invention can be made and practiced in other specific forms without departing from the spirit and essential characteristics thereof. Therefore, the present embodiments are considered in all aspects as illustrative and not restrictive. The purpose of the invention is indicated by means of the appended claims rather than by the description of the foregoing. All variations, substitutions and changes that come within the meaning as well as the equivalence range of the claims, therefore, are intended to be included in the present.

Claims (7)

1. CLAIMS 1. a full-scale miniature speaker, consisting of: a circular diaphragm having a predetermined diameter in a perimeter thereof; a moving coil shape, having an outer diameter approximating that of said diaphragm, a leading end and a trailing end, the leading end coaxially joined to said diaphragm in a peripheral region thereof; a moving coil, wound in a rear region of the movable coil shape, which extends forward towards the middle region thereof, thus leaving a free space in said mobile coil form between the moving coil and the diaphragm; a magnet assembly made and arranged to define an annular gap with the magnetic flux passing through the voice coil in a known allowable manner for loudspeakers; a cylindrical side wall of the speaker, which surrounds the assembly of the magnet and the moving coil; an annular mounting ring which surrounds the side wall and which is attached thereto in a front region thereof, configured to provide a surface with an annular planar front suspension arranged in a plane that is perpendicular to the central axis of the speaker and which is locates between the forward end of the moving coil and the forward end of the moving coil shape; and an annular peripheral suspension member of flexible material, which surrounds the mobile coil shape and which has an outer flange attached to the rear side thereof on the suspension connecting surface of said mounting ring and the inner edge which is joined by the edge to the free space of the mobile coil shape between the moving coil and the diaphragm.
2. 2. The full-scale miniature loudspeaker as defined in claim 1, characterized by said peripheral suspension member having a radial cross-sectional shape, generally configured as an arc extending forward between the outer flange and a flange inner narrower than the outer flange, which extends to the inner edge of the peripheral suspension member.
3. 3. The full-scale miniature loudspeaker, as defined in claim 2, wherein the arc has an angle not exceeding 180 degrees.
4. 4. The full-scale miniature loudspeaker, as defined in claim 3, wherein the diaphragm is configured to have a concave shape, such that the perimeter of the diaphragm defines a more forward region thereof.
5. 5. The full-scale miniature loudspeaker, as defined in claim 4, wherein: the outer flange of the suspension member is configured with a rear jointing surface made and arranged to interconnect the mounting and suspension surface of the mounting ring; and the inner edge of such peripheral suspension member is located substantially in a common plane with the outer flange thereof.
6. 6. The full-scale miniature loudspeaker, as defined in claim 5, wherein: the inner edge of the peripheral suspension member is attached at the edge to the free space of the movable coil shape at a location that is deflected backward from the perimeter of said diaphragm, such that a point on the surface that is further forward of said peripheral suspension member and the perimeter of such diaphragm, are located substantially in a front plane of the loudspeaker.
7. 7. The full-scale miniature loudspeaker, as defined in claim 5, wherein: the peripheral suspension member is made to have a predetermined thickness in a region thereof, between a point on the surface thereof which is further forward and the rear joining surface of the outer flange.