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US 4,054,748 AGranted
Cardioid electro-acoustic radiator
AssigneeElektroakusztikai Gyar
InventorGeza Balogh
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AssigneeElektroakusztikai Gyar
InventorGeza Balogh
Estimating the term…
The subject matter of the invention is a directional electro-acoustical converter, primarily a cardioid sound radiator which, in spite of its small dimensions, has cardioid directivity diagram and at the same time wide transmission band. The known solutions of the cardioid sound radiator have frequency responses falling towards the low frequencies thus being generally suitable for the transmission of speech informations. On the contrary, the directional converter according to the invention provides for a wide transmission band in the loudspeaker operating method being thus suitable for the transmission of musical programs, too. To the membrane of the converter according to the invention at least two phase shifting members having different sound route distances are coupled by means of acoustic coupling elements. The phase shifting members, and their coupling elements, respectively, have such a value that the quarter of the wave length corresponding to the transposition frequency produced by them is at least identical with, but at most the quadruple of the value of the smallest sound route distance. With this solution a nearly straight frequency response within the transmission band, cardioid directivity diagram and various variants thereof, respectively, can be provided for.
Directional electro-acoustical converter, comprising an electrodynamic moving-coil loudspeaker and sound radiator, at least two phase shifting members equalized to the second degree, said phase shifting members having apertures and being disposed at different distances from the front side of a membrane of the loudspeaker, the phase shifting member which is at the smallest distance (d.sub.2) from the membrane being coupled directly to the membrane or by means of an acoustic resistance (R.sub.cc) or by means of an auxiliary membrane (C.sub.cc), said other phase shifting members at greater distances (d.sub.3, d.sub.4 . . . ) from said membrane being coupled to the membrane each by means of at least one acoustic resistance (R.sub.c, R.sub.c ', r.sub.c . . . ) or each by means of at least one mass (m.sub.c, m.sub.c ') such that the quarter of the wavelength .lambda..sub.k belonging to the transposition frequency (f.sub.k) determined by the phase shifting members having d.sub.2 and d.sub.3 sound route distances has one to four times the value of the smallest sound route distance D.sub.2, whereby d.sub.2 .ltoreq. (.lambda.k/4) .ltoreq. 4d.sub.2.
Dependencies are inferred from the claim text.