 Expansion circuit for improved stereo and apparent monaural image |
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| Color video display for audio signals |
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| Source data compression and decompression in code symbol printing and decoding |
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| Noise eliminating circuit |
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Double diaphragm electrostatic transducer each diaphragm comprising two plastic sheets having different charge carrying characteristics
| Details |
Inventors: Driver, Michael L.;
Assignee:
Primary Examiner: Stellar; George G.
Assistant Examiner:
Attorney, Agent or Firm: Haefliger; William W.
An electrostatic transducer, such as a loudspeaker, employs parallel plastic diaphragms, each carrying an electrically conductive metallic layer; frames separately mounting the diaphragms, the frames assembled to a central, perforate electrically conductive sheet sandwiched between the diaphragms, and to foraminous sheets of dielectric material sandwiched between the central sheet and the diaphragms and frames, thereby to realize a compact, easily assembled unit characterized by very high performance qualities. |
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DETAILED DESCRIPTION In FIGS.
1 and 2, loudspeaker 10 is shown to comprise a pair of spaced, generally parallel diaphragms 11, each of which includes a first sheet 12 of plastic material, and an electrically conductive layer 13 adherent to that sheet.
Typically, each sheet 12 consists of polyester film of about 0.
00025 inch thickness, and is peripherally wrapped at 12a over a supporting frame 14 of insulative material.
Frames 14 are shown as generally rectangular, in FIG.
2, and as extending in parallel, spaced apart relation, in FIG.
1.
The layer 13 may consist of a metallized layer on sheet 12, and also wrapped about the frame.
Each diaphragm may also include a second sheet 15 of plastic material at the opposite side of layer 13.
Sheet 15 is also peripherally wrapped at 15a about the frame, and the diaphragm is typically stretched by such wrapping so that the free extent 11a of the diaphragm inwardly of the frame is in taut condition, free to oscillate back and forth in the direction of arrows 16 in FIG.
1.
The tension exertion on each diaphragm is a minimum of about 10 inch ounces.
The sheets 12 and 15 respectively and advantageously consist of polyester and vinylidene chloride, both being films and of respective thicknesses of about 0.
00025 inch and 0.
0015 inch.
Polyester film carries a low level static charge, owing to its chemical composition, which is employed to advantage in the final mill rolling or winding of the film.
Static charges can be placed on polyester film readily by rubbing or brushing with dissimilar material.
Such charges, however, migrate at random and dissipate rather quickly.
Vinylidene chloride carries a relatively larger static charge on a permanent basis; it adheres to itself readily, and is widely sold and used under the trade name "SARAN.
" Also, in a flame test, vinylidene chloride is self-extinguishing.
When placed in close relation with polyester film, and operated as a capacitive transducer, the vinylidene chloride film causes the capacitive junction to exhibit self-healing characteristics when driven to the point where arcing or high voltage corona occurs
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Audio Signal Processing 
