US 6,298,140 B1Granted

Electroacoustic transducer with improved tonal quality

OwnerChristos Manavopoulosinventor

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Abstract

An electroacoustic transducer with attenuated effective output irregularities caused by intrinsic normal modes of oscillation. What stands out, as a structural property of a preferred embodiment, is a sandwich assembly, having an oscillating medium of layered components suspended between two rigid baffles, with a hinged baffle extension supporting the device in upright position. An opening, asymmetrically positioned in each of said two rigid baffles, exposes to the ambient medium a driven and asymmetrically positioned antinode belonging to a predetermined mode pattern of the oscillating medium. The resulting asymmetrical and partial coupling of the oscillating medium with the ambient medium limits occurrences of irregularities in effective output. Similarly, the asymmetrical and partial driving of the oscillating medium leads to a relatively high number of normal modes simultaneously excited. Moreover, perturbations in boundary conditions of the oscillating medium give rise to additional superposed standing waves, for a further increase in the number of normal modes simultaneously excited. The resulting higher density of normal modes limits perception of irregularities in effective output. This combined process of limiting both occurrences and perception of irregularities stands out as a functional property of the device for an effective output with improved tonal quality.

Claims20

Dependent claims

A transducer for accurately and efficiently reproducing a stimulus applied thereupon, operating in a fluid ambient medium, having an effective output spectrum defined within a predetermined effective range of frequencies, comprising:

(a) an oscillating medium assembly of layered components suspended in said ambient medium, comprising at least one oscillating member delimited by at least one supporting member with predetermined geometry defining the boundary of said oscillating member;
(b) said oscillating medium with predetermined boundary conditions imposed on the oscillatory motion of said oscillating member;
(c) said oscillatory motion induced by standing waves associated with the intrinsic normal mode patterns of antinodes delimited by nodes, and with the characteristic frequencies of said oscillating member;
(d) said stimulus applied to an asymmetrically positioned, and substantially adjacent to the boundary of said oscillating member, antinode of a normal mode pattern associated with a predetermined characteristic frequency high enough to satisfy the condition of said antinode being substantially adjacent to said boundary of said oscillating member;
(e) said extreme position of said antinode giving rise to values of quality factor Q distributed asymmetrically with respect to the consequent extreme position of the oscillatory forces exerted by said stimulus on said oscillating member;
(f) driving means for coupling said stimulus to said oscillating member by way of said asymmetrically positioned, and substantially adjacent to said boundary of said oscillating member, antinode, so that a substantially high effective density of normal modes and associated characteristic frequencies is derived from a substantially high number of concurrently excited normal modes;
(g) said substantially high number of concurrently excited normal modes resulting from said stimulus being coupled to antinodes delimited by oscillating nodal lines crossing said antinode;
(h) said oscillating nodal lines resulting from partial amplitude cancellations along expected positions of nodes associated with normal modes of oscillation concurrently excited by said stimulus;
(i) said partial amplitude cancellations resulting from amplitude differentials of incident and reflected waves;
(j) said amplitude differentials resulting from applying said stimulus at the extreme asymmetrical position of said antinode, and expected from said asymmetrically distributed quality factor Q of said oscillating member;
and
(k) means for attenuating effective output irregularities caused by said oscillating medium interacting with said ambient medium;
whereby, a balanced energy distribution in the spectrum of the effective output will be derived from a high effective density of normal modes and from a simultaneous attenuation of irregularities caused by interaction of oscillating with ambient medium, so that said transducer will reproduce an improved approximation of said stimulus at source.

10 more elements

An electroacoustic transducer operating in an ambient fluid comprising:

(a) three panels, of predetermined geometry, assembled as a sandwich configuration of an inner module, a first outer module and a second outer module;
(b) said inner module comprising a pair of stretched thin films, of predetermined geometry, and an inner baffle therebetween, together forming a layered oscillating medium assembly hermetically sealed to form a fluid-containing cavity, said thin films each having an asymmetrically positioned driven/radiating area, said inner baffle having a port therein, asymmetrically positioned and aligned with said driven/radiating areas of said thin films, whereby said thin films are coupled in the area defined by said port and decoupled in the remaining non-driven area defined by the solid segment of the inner baffle;
(c) a geometrical perturbation in the boundary of each of said thin films, causing two oscillating regions to be defined therein and coupled by way of said driven/radiating area;
(d) each of said outer modules comprising an outer baffle with an asymmetrically positioned port therein, aligned with said driven/radiating area, through which port said layered oscillating medium assembly is coupled with said ambient fluid in the driven/radiating area;
and
(e) motor means for generating generally uniform and linear forces across said driven/radiating area of said thin films.

3 more elements

A method of limiting detection of irregularities in effective output of an electroacoustic transducer operating in a fluid ambient medium, having an oscillating medium with predetermined boundary and boundary conditions defined by supporting components, said irregularities being caused by resonances of said components and resonances of said oscillating medium interacting with said ambient medium fluid, comprising the following step in the design, construction and operation of said transducer:

(a) deriving a high density of intrinsic normal modes concurrently participating in the process of reproducing a stimulus;
(b) said stimulus being applied on a predetermined section of said oscillating medium coincident with an antinode of a predetermined normal mode pattern;
and
(c) said section being asymmetrically positioned and substantially adjacent to said boundary of said oscillating medium.

1 more element

An electroacoustic transducer for audio reproduction having components for adjustment of operating parameters to produce smooth frequency response with balanced output over a selected range of the audio spectrum, comprising:

(a) a frame for an oscillating medium;
(b) an oscillating medium mounted in said frame for oscillatory motion;
(c) means for driving said oscillating medium in response to an audio stimulus, asymmetrically applied with respect to boundary of said oscillating medium;
(d) said components comprising at least three clamps applied at specific areas on the periphery of the oscillating medium to increase the density of modes of vibration;
(e) one of said clamps being set to restrain movement of the oscillating medium at its periphery to multiply the number of natural mode patterns and associated characteristic frequencies by increasing the number of superposed standing waves generated by the driven area of the oscillating medium;
(f) a second of said clamps being variably positionable across the width of said oscillating medium near to the driven area, so as to fine tune the interlacing of characteristic frequencies in the frequency domain by shifting the high frequency end of the selected range;
and
(g) a third of said clamps being variably positionable across the width of said oscillating medium distant from the driven area, so as to fine tune the interlacing of characteristic frequencies in the frequency domain by shifting the low frequency end of the selected range;
whereby said oscillating medium of said electroacoustic transducer will limit perception of resonance-antiresonance irregularities in effective output, caused by the intrinsic normal modes of oscillation of the oscillating medium.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/252,723Filed 19 Feb 1999 · us provisional application
Priority: 20 Feb 1998
Granted: 2 Oct 2001
Term ends: Not estimatedThe source records don’t support an estimate.

Classification2 codes

H04R 7/045
Plane diaphragms: using the distributed mode principle, i.e. whereby the acoustic radiation is emanated from uniformly distributed free bending…
H04R
Loudspeakers, microphones, gramophone pick-ups or like acoustic electromechanical transducers

Family

Application60/075,368Us provisional application · filed 20 Feb 1998
US 6,298,140 B1This patent

From the US filing history. Foreign family members aren’t listed.

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