DE1139548B - Multi-unit electrostatic speaker - Google Patents

Description

The invention relates to multi-unit electrostatic speakers. Underneath one understands speakers whose excitation is based on the electrostatic attraction between a movable or flexible membrane electrode and at least one rigid, parallel to it attached Plate electrode is based.

Such speakers have, if they are to reproduce a wider audio frequency range, in of the membrane area larger dimensions for physical reasons. It is known to be in several To subdivide units, with the aim of dividing the individual units only into partial areas of the to let the transmitted audio frequency work.

On the other hand, it is known that for purposes of stereophonic performance at least two at a distance upright loudspeakers must be used that are fed via at least two transmission channels.

In a known one, which is divided into partial capacitances and switched as a delay line electrostatic speaker, this is only fed from one end while the other end is due to a terminating resistor. So this loudspeaker only acts as a loudspeaker, merely the direction of radiation forms an angle with its perpendicular surface normal.

The invention relates to a multi-unit electrostatic loudspeaker for Stereophonic reproduction, in particular for use in connection with slide shows.

According to the invention, a stereophonic reproduction method having new properties is thereby achieved obtained that the units alternating current in a manner known per se than the successive Elements of an electrical delay line are connected, which in turn are connected to their both ends are fed with audio frequency signals from the stereophonic transmission channels.

For example, a number of loudspeaker units can be placed side by side along the wall of a room, each unit being coupled to the neighboring one via a suitable choke is.

If an audio frequency signal is now fed to one end of this delay line, there is a certain time delay along the room for the electrical vibrations transmitted to the loudspeaker membrane surfaces. It follows from this that the wave front of the sound no longer runs parallel to the loudspeaker membrane, but is angled at an angle. One at the other end of the ver-made up of several units
electrostatic speaker

Applicant:

Braun Aktiengesellschaft,
Frankfurt / M., Rüsselsheimer Str. 22

Claimed priority:
Great Britain, July 20, 1954 (No. 21 070)

David Theodore Nelson Williamson, Edinburgh,
and Peter James Walker, Huntingdon

(Great Britain),
have been named as inventors

Separate audio frequency voltage supplied to the delay line creates a wavefront of the same Lean, but in the opposite direction.

Since the perceived direction of a sound source is always perpendicular to the wave front, it follows from this that the observer perceives two sound sources whose position angle is constant and in one wide area completely independent of the position of the listener, although only one loudspeaker, albeit with an extensive frontal area.

Such an arrangement is shown as a block diagram in the drawing. The delay line is formed in that a number of chokes 85 are connected in series along the line 86 and points of the line 86 lying between the throttles with opposite points of the line 87 are connected by means of the plate electrodes of the loudspeaker units 88, which therefore act as shunt capacitors. The speaker cones are parallel to each other with connected to one pole of a high voltage source 89, the other pole of which is grounded. Incoming low frequency signals are fed to the two ends of the line via the transformers 90. they were recorded in a suitable manner in the broadcast studio spatially distributed microphones (not shown).

The series chokes 85 do not need to be separate switching elements. The plate electrodes one each speaker unit 88 can be self-throttling

209 707/224

are made, for example, in that they are sprayed onto perforated insulating plates in a spiral Conductor materials exist, with the breakthroughs required for sound radiation between the spiral turns.

A real binaural effect can thereby be achieved be that with a loudspeaker with a large total surface, its units side by side are arranged along an auditorium, these scanned horizontally and if necessary also vertically are simultaneously with a similar scan of a number of microphones in the broadcast studio. This scanning can be done electronically or by means of a simple rotating dial will. In such a case, a replica of the sound waves is made in the auditorium, who go through a level in the concert hall.

This structure of electrostatic speakers with a large total area is when used in Cinemas of importance, especially when the radiating surface of the speaker is the screen on which the image is projected. For this purpose his can be turned towards the listener Outer surface, e.g. B. one of the perforated plate electrodes, reflective beads applied be, as is usual with cinema screens, or preferably a structure of small lenses that so are dimensioned so that they result in perfect light distribution.

Claims (3)

PATENT CLAIMS: 1. Electrostatic loudspeakers consisting of several units for stereophonic reproduction, in particular for use in connection with slide shows, characterized in that the units are connected to alternating currents in a manner known per se as the successive members of an electrical delay line, which in turn have audio frequency signals at their two ends is fed from the stereophonic transmission channels. 2. Electrostatic loudspeaker according to claim 1, whose fixed electrodes consist of a one-sided consist of insulating bodies clad with an electrically conductive layer, characterized in that that the conductive layer is formed by appropriate division into a current path as the inductance of the delay line is. 3. Electrostatic loudspeaker, in particular large loudspeaker, according to claim 1 or 2, characterized characterized in that its outer surface facing the listener in the case of screens is prepared in the usual way. Considered publications:
German patent specification No. 627 679. 1 sheet of drawings © 209 707/224 11.