Claims
- 1. An electrodynamic electro-acoustic transducer having an acoustic axis, said transducer comprising:a pleated ribbon diaphragm having a plurality of half-pleats each extending along a first direction perpendicular to the acoustic axis of the transducer and each adapted to move in an accordion-like manner in a second direction perpendicular to both said first direction and to said acoustic axis of the transducer, said first and second directions defining a diaphragm plane; an electrical conductor comprising one or more conductive strands each extending along a respective one of said half pleats parallel to the diaphragm plane; a horn having at least an outer portion that is perpendicular to the diaphragm plane; a magnetic front pole plate extending across a front side of an active area of the diaphragm and disposed between said active area and the horn for providing an acoustic conduit between said active area and the horn a rear pole plate extending across a rear side of the active area and cooperating with the magnetic front pole plate for orienting a magnetic field in a direction perpendicular to said active area, wherein: the front and rear pole plates each comprises a plurality of openings, each of the openings in the front pole plate extends from a rear surface adjacent the active area of the diaphragm transducer to a front surface adjacent an interior portion of the horn, the rear open area of each of the openings in said rear surface is less than the corresponding front open area of that same opening in said front surface, and the ratio of rear open area to the front open area in the front pole plate is substantially constant for all portions of the active area of the diaphragm.
- 2. The transducer of claim 1 wherein the open area increase in a substantially exponential fashion from the rear surface to the front surface.
- 3. The transducer of claim 1 wherein the open area increases in two axes that are each perpendicular to the acoustical axis of the horn.
- 4. The transducer of claim 1 wherein the magnetic front pole plate is integrally formed from a single plate of magnetic material.
- 5. The transducer of claim 1 wherein the magnetic front pole plate comprises a plurality of slits arranged in a vertical array and each extending horizontally across all of the conductive segments.
- 6. The transducer of claim 1 wherein the magnetic front pole plate comprises a plurality of apertures arranged in a planar array comprising several rows and several columns.
- 7. The transducer of claim 1 wherein the height of each of the openings increases from the rear surface to the front surface.
- 8. The transducer of claim 1 wherein the width of each of the openings increases from the rear surface to the front surface.
CLAIM TO PRIORITY
This application is a continuation PCT/US97/20202 filed Nov. 6, 1997. This application is based on, and claims priority from, US Provisional Applications 60/030,230 filed Nov. 7, 1996 and 60/029,550 filed Nov. 8, 1996, which are hereby incorporated by reference in their entirety.
US Referenced Citations (2)
Provisional Applications (2)
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Number |
Date |
Country |
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60/030230 |
Nov 1996 |
US |
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60/029550 |
Nov 1996 |
US |
Continuations (1)
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Number |
Date |
Country |
Parent |
PCT/US97/20202 |
Nov 1997 |
US |
Child |
09/307318 |
|
US |