AU621948B2

AU621948B2 - Electro-acoustic transducer

Info

Publication number: AU621948B2
Application number: AU44316/89A
Authority: AU
Inventors: Jean-Claude Fourriere
Original assignee: HAUT LANGUEDOC ACIERIES
Current assignee: ACIERIES DU HAUT LANGUEDOC
Priority date: 1988-11-10
Filing date: 1989-11-02
Publication date: 1992-03-26
Anticipated expiration: 2009-11-02
Also published as: ATE92701T1; EP0370846B1; FR2638930B1; CA2002803A1; JPH02174398A; DE68908100D1; FR2638930A1; AU4431689A; EP0370846A1

Abstract

- The present invention relates to an electroacoustic transducer, comprising at least one element (2) capable of emitting ions when it is brought to a sufficiently high electrical potential, the said element being arranged between two first electrodes (4, 5), which are parallel to one another and connected to a modulator (6), and between which a modulated electric field acting on the said ions is capable of being created. - According to the invention, it comprises at least one second electrode (8, 9) which is brought to an electrical potential such that a flux of ions (10) is created between the said emitter of ions (2) and the said second electrode (8, 9), and which is disposed in the vicinity of the said ion emitting element (2) so that the said modulated electric field acts on the said flux of ions (10). - The invention applies to acoustic enclosures. <IMAGE>

Description

AUSTRAL2AV PATENTS ACT 1952 Form COMPLETE SPECIFICAV

(ORIGINAL)

FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: TO BE COMPLETED BY APPLICANT Name of Applicant: ACIERIES DU HAUT LANGUEDOC Adaress of Applicant: 212 ROUTZ DE PRESSANCE 30100 ALES

FRANCE

Actual Inventor: Address for Service: GRIFFITH HACK CO., 601 St. Kilda Road, Melbourne, Victoria 3004, Australia.

Complete Specification for the invention entitled: ELECTRO-ACOUSTIC TRANSDUCER.

The following statement is a full description of this invention including the best method of performing it known to me:- FIELD 0F THE INVENTION The present inlvention concerns an olectro-acoustic transducer, as wall as a column speaker comprising at least one such transducer.

BACKGROUND OF THE INVENTION There is already known to exist via the French patent application no. 2 246 151 an electro-acoustic transducer comprising a wire capable of transmitting ions when it is to a sufficiently high potential, said wire being between two electrodes parallel to each other and connected to a modulator, an electric field acting on said ions being able to be created between said electrodes. Said ions ara then set to operate and, by moans of collisions, transmit the energy thus acquired at neutral surrounding molecules by producing a sound at the frequency of the modulated electric field. In this case, however, the ionic current is extremely localised immediately adjacent to the wire, so that the results obtained are scarcely satisfactory in practice.

SUMMARY OF THE INVENTION The object of the present invention is to substantially overcome these drawbacks and concerns an eJlectro-acoustic transducer whose effectiveness has been considerably improved.

According to the present invention there is provided an electro-acoustic transducer comprising: at least one element capable of transmitting ions when it is brought to a sufficiently high electric potential, said ion transmitter element being disposed between two first electrodes parallel to each other, said electrodes being connected to a modulator, said modulator adapted to produce a modulated electric field which acts on said ions between said first electrodes, I 1--I rc~ I at least one second electrode being provided and brought to such an electric potential that an ion current is created between said ion transmitter element and said at least one second electrode, the latter being disposed adjacent to said ion transmitter element and intermediate said first electrodes so that said modulated electric field acts on said ion current.

Consequently, said ionic current plays the role of an immaterial vibrating diaphragm. In effect, the ionised fluid, created between the ion transmitter element and the second electrode, is attracted by the first electrodes at the rate of modulation by thus generating acoustic pressures in the air.

In the case where said ion transmitter is a wire, two said second parallel electrodes are advantageously provided respectively on both sides of said wire, said second electrodes being orthogonal to said first electrodes. Said second electrodes are preferably disposed at distances equal to said wire. Said wire, made in particular of stainless steel or platinum, may have a diameter of between 20 and 50 micrometers.

t In the case where said ion transmitter element is a point, either a plurality of punctual second electrodes are disposed Sfan-shaped around said point or said second electrode roughly •has the shape of a horseshoe encompassing said point.

3 According to a further characteristic of the invention, said first electrodes are disposed at equal distances from said ion transmitter element.

Advantageously, said first electrodes are grids made of a rigid textile material coated with carbon.

Preferably, said ion transmitter element is brought to a negative potential of at least about -4.5 kV.

BRIEF DESCRIPTION OF THE DRAWINGS The figures of the annexed drawing clearly show how the invention may be embodied. Identical references on these figures denote similar elements.

Figures 1 and 2 illustrate a first example of the embodiment of the electro-acoustic transducer of the invention and in which the ion transmitter element is a wire.

Figures 3 and 4 and 5 and 6 respectively illustrate two vatiants of a second example of the embodiment of the electro-acoustic transducer of the invention and in which the ion transmitter element is a point.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to figures 1 and 2, the electro-acoustic transducer 1 comprises a wire 2 connecteo to a high voltage source 3 capable of transmitting ions when it is brought to a sufficiently high electric potential, for example a negative potential of about at least kV, this negative potential not yielding any noise 4 discharge. The wire 2 is disposed between two first electrodes 4,5 parallel to each other and connected to a modulator 6 by means of a transformer 7. A modulated electric field may thus be created between the two electrodes 4, 5 so as to act on said ions. The electrodes 4, 5 are advantageously embodied in the form of grids made of a rigid textile material coated with carbon. Owing to this, the formation of arcs in the presence of high modulations occurs very rarely and such modulations are not maintained, as would be the case with metallic grids.

In addition, two second electrodes 8, 9 parallel to each other connected to the ground are respectively disposed on both sides of the wire 2, said second electrodes 8, 9 being orthogonal to said first electrodes 4,5. Moreover, it is appropriate to mention that the first 4, 5 and second 8, 9 electrodes are advantageously respectively disposed at equal distances from the wire so as to avoid creating an ionic wind at the time the negative polarization voltage is applied.

The modulated electric field created between the first electrodes 4, 5 thus acts on the ionic current generated between the wire 2 and the second electrodes 8,9, said ionic current playing the role of an immaterial vibrat'ng diaphragm. In other words, the ionized fluid created between the wire 2 and the ground electrodes 8,9 is attracted by the grids 4, 5 at the modulation rate by thus producing acoustic pressures in the air.

In the two variants of the embodiment example of the electro-acoustic transducer 1 both illustrated by figures 3 to 6, the ion transmitter wire is replaced by a point.

The point II is disposed inside a supporting ring 12 so that the end lila of the latter is at the center of said ring 12. As in the preceding case, the point 11 connected to a high-voltage source 13 is able to transmit ions when it is brought to a sufficiently high electric potential, such as a negative potential of :0 about -4.5 kV, Also the point 11 and in particular the end lla of the latter are disposed between two first electrodes 14, 15 parallel to each other and connected to a modulator 16 by means of a transformer 17. These electrodes 14, 15 are advantageously of the same type as the electrodes 4,5 described previously.

In a first variant illustrated by figures 3 and 4, a plurality of second punctual electrodes 18 (for example, three electrodes) connected to the ground are disposed fan-shaped around the end lla of the point 11.

In the second variant illustrated by figures 5 and 6, a second single electrode 19 connected to the ground has 0 roughly the shape of a horseshoe and encompasses the end 1la of the point 11.

As in the preceding case, the modulated electric field, created between the first electrodes 14, 15 and the point 11, acts on the ionic current 20 generated between the point 2 and the second electrode(s) 18,19, said current acting as an immaterial vibrating diaphragm.

A

Claims

1. Electro-acoustic transducer comprising: at least one element capable of transmitting ions when it is brought to a sufficiently high electric potential, said ion transmitter element being disposed between two first electrodes parallel to each other, said electrodes being connected to a modulator, said modulator adapted to produce a modulated electric field which acts on said ions between said first electrodes, at least one second electrode being provided and brought to such an electric potential that an ion current is created between said ion transmitter element and said at least one second electrode, the latter being disposed adjacent to said ion transmitter element and intermediate said first electrodes so that said modulated electric field acts on said ion current.

2. Electro-acoustic transducer according to claim 1, comprising two second electrodes and wherein said ion transmitter element is a wire, said second electrodes disposed parallel to each other and on opposite sides of said wire, said second electrodes being orthogonal to the first electrodes.

3. Electro-acoustic transducer according to claim 2, wherein the second electrodes are disposed at equal distances from said wire.

4. Electro-acoustic transducer according to claim 2 or 3, wherein said wire has a diameter of between 20 and micrometers.

Electro-acoustic transducer according to any one of claims 2 to 4, wherein said wire is made of stainless steel or platinum.

6. Electro-acoustic transducer according to claim i, wherein said ion transmitter element is a point and said at least zr- one second electrode comprises a plurality of point-shaped electrodes disposed fan-shaped around said point.

7. Electro-acoustic transducer according to claim 1, wherein said ion transmitter element is a point and said at least one second electrode comprises an electrode which is substantially horseshoe shaped and encompasses said point.

8. Electro-acoustic transducer according to any one of the preceding claims, wherein the first electrodes are disposed at equal distances from said ion transmitter element.

9. Electro-acoustic transducer according to any one of the preceding claims, wherein the first electrodes are grids made of a rigid textile material coated with carbon.

Electro-acoustic transducer according to any one of the preceding claims, wherein said ion transmitter element is brought to a negative potential of at least about -4.5 kV.

11. Column speaker including at least one elec'ro-acoustic transducer according to any one of the preceding claims.

12. Electro-acoustic transducer substantially as herein described with reference to and as illustrated in the accompanying drawings. Dated this 13th day of January, 1992. ACIERIES DU HAUT LANGUEDOC By its Patent Attorneys: GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia.