U.S. Philips Corporation

Wilhelmus D Van Gijsel

Joris A Nieuwendijk

Georgius B Sanders

Jacob M Van Nieuwland

Franciscus J Op De Beek

An electrodynamic transducer (1) for use in a loudspeaker system for converting an n-bit digitized electric signal (11) into an acoustic signal comprises n voice-coil devices (4.1, 4.2, . . . 4.n) which cooperate with a magnet system (3). The voice-coil devices each comprise a conductor whose length is the same for all the voice-coil devices. The areas of the perpendicular cross-sections of the conductors increase each time by a factor of two starting from the voice-coil device (4.n) corresponding to the least significant bit and going to voice-coil devices corresponding to consecutive more significant bits. The invention enables the transducer to be constructed in a simple manner if the transducer is a moving-coil loudspeaker or if it is a ribbon-type loudspeaker.

Loudspeaker system for converting a digitized electric signal into an

A loudspeaker system for converting an n-bit digitized electric signal (11) into an acoustic signal comprises an electrodynamic loudspeaker (1) with n voice-coil sections (4.1, 4.2, . . . 4.n) which cooperate with a magnet system (3). The loudspeaker system further comprises means (18.1, 18.2, . . . 18.n) for short-circuiting a voice-coil section if the value of the bit corresponding to the voice-coil section is such that the relevant voice-coil section is not driven.

Loudspeaker system and loudspeaker for use in a loud-speaker system for

In a loudspeaker system for converting an n-bit digitized electric signal (6) into an acoustic signal a plurality of sections (voice coils 14.1, 14.2, 14.3, 14.p) of a digital loudspeaker (1) are driven directly by the p most significant bits of the n-bit digitized electric signal (6). The loudspeaker (1) comprises at least one additional section (14.p+1). This (p+1).sup.th voice coil receives a signal from a digital-to-analog converter (5), the input signal of the digital-to-analog converter comprising at least the n-p least significant bits (FIG. 2). In a different embodiment the digital-to-analog converter (5) receives all the n bits of the digitized electric signal as the input signal. At least the p sections (14.1 to 14.p) which correspond to the p most significant bits are provided with means (the resistances r) for producing a signal which is a measure of the sum of their instantaneous drive signals and for applying the said signal to a signal combination unit (32) arranged in the line (10) from the output of the digital-to-analog converter (5) to the (p+1).sup.th section (R.sub.1). By means of this correction circuit the distortion in the loudspeaker system can be reduced substantially (FIG. 3b).

Hybrid loudspeaker system for converting digital signals to acoustic

A ribbon-type electro-acoustic transducer comprising a magnet system having a pole plate (2, 3) and a center pole (1) between which at least one air gap (8) is formed with a diaphragm (7) arranged in the air gap (8). The diaphragm comprises at least two foils (10, 11) which extend substantially parallel to each other in the diaphragm plane, every two adjacent foils being joined to each other at their circumference in an air-tight manner so that a volume (12) is enclosed. A conductor (9, 18) is arranged on each of the foils. Preferably the volume enclosed between two foils contains a damping material (22).

Ribbon-type transducer with a multi-layer diaphragm

A ribbon-type electro-acoustic transducer has a magnet system which comprises an upper plate (2, 3) and a center pole (1) between which an air gap (8) is formed. A diaphragm (7) on which conductors (9) are arranged is disposed in the air gap. The upper plate (2, 3) comprises two plate-shaped parts (2', 3' and 2', 3' respectively) between which a space (11) is formed in which an edge portion of the diaphragm is located. This results in a more homogeneous magnetic field so that the transducer distortion may be reduced. Moreover, the transducer sensitivity is improved and is suitable for handling signals in the mid-range audio frequency spectrum. The cavity (15) enclosed by the magnet system and the diaphragm (7) can be acoustically coupled, be via an additional cavity to a (bass-reflex) duct or an additional (passive radiator) diaphragm.

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Eindhoven, Netherlands

Wilhelmus D Van Gijsel