Electrostatic loudspeaker

Abstract

Electrostatic loudspeaker, characterized by that two rows of round, oval or teardrop-shaped conductive stators (outer electrodes) (1 and 2) are attached or fixed in a base and cover plate (12 and 10). These have a uniform and thin insulating layer on the outside with high dielectric strength against electrical voltage. The arrangement of the front row is spaced according to the diameter of the stators (1 and 2) and the intended use (frequency range to be radiated). The rear row of stators (2) is offset, placed between two stators (1) of the front row, where the diameter of the stators (1 and 2) and the desired frequency range determine the distance to the two front stators (1). A thin conductive or coated foil (4) is guided around these stators (1 and 2) in a wave-like pattern and is not stretched.

Description

[0001] There are various different types of loudspeakers. In addition to a few special types, there are the well-known dynamic loudspeakers and electrostatic loudspeakers. Electrostatic loudspeakers consist of a very thin foil clamped firmly in a frame, which is charged with a high electrical voltage. In front of and behind this foil is a perforated metal plate or tightly stretched, insulated cables, the so-called stators. This design is called the push-pull principle. The audio signal is applied to the stators at a rate of several hundred volts. The foil has a constant plus or minus charge, and the polarity at the stators constantly changes with the music signal. Since like charges repel and unlike charges attract, the foil is moved. This movement is called stroke and produces the high-quality, audible music.But these electrostatic forces aren't very strong; they have to work against the tension of the foil, forcing the air through the holes in the metal plate or through the cable gaps. Therefore, a very large foil is necessary, and therefore very large speakers, which leads to sound bundling, especially in the high-frequency range. The very small excursion prevents deep bass frequencies. Material fatigue, dust, and other deposits make a complicated and costly foil replacement necessary. Room acoustic problems also arise.

[0002] This invention counteracts these problems.

[0003] Two rows of round, conductive metal tubes are attached between a base plate and a ceiling plate; these form the stators. A uniform insulating layer with a high dielectric strength against electrical voltage has been applied to the outside of these tubes. These stators are arranged one behind the other and offset. This arrangement is already described in a similar way in patent DE 3118239 C1.

[0004] A thin foil is wrapped around these stators, which is conductive or has been made conductive by a surface coating. This way of guiding the foil creates tension in the material and ensures high dimensional stability. The model for this is corrugated iron, a thin sheet on which you can even walk through the mold. The foil is not mechanically tensioned and does not rest on anything, but is attached at both ends to a rotating tube or round rod. This is used to wind up or unwind the foil, precisely adjusting the length of the foil between the stators. This sets the distance between the foil and the stators. The required electrical charge is also supplied to the foil at this attachment. The front and rear rows of stators are connected to the music signal separately. The foil attachments are an exception to this. The rows of stators are arranged in an outwardly curved radius.The speaker width is acoustically and visually optimized, and the speaker height is variable. This elongated, narrow, and curved design results in more even sound distribution within the listening room and an expansion of the stereo listening zone. Disturbing ambient influences are minimized and a high direct sound component is ensured. The large foil (a factor of 3.5 to the speaker width), combined with the long excursion and the fact that the entire foil is driven, delivers a wide frequency range at very good volume. The unstretched foil and no inhibiting stators ensure optimal impulse response. Material fatigue cannot occur, and foil replacement is quick and easy. To prevent acoustic short circuits, the speaker is installed in a rear-open cabinet and lightly sound-insulated at the rear, which further reduces room resonance.This speaker can also be operated without any changes in technology as described in US Patent Publication Number US000007054456B2.

[0005] In addition, this invention uses a new type of force applied to the foil for electrostatic loudspeakers, the inverted push-pull principle. Fig. 3 shows a sine wave.

[0006] The function is explained using the framed negative half-wave.

[0007] Fig. 4 shows the inverted push-pull principle.

[0008] In this example, there is a positive charge on the foil.

[0009] The front and rear rows of stators always operate with opposite signal polarity, except for the zero crossing of the sine wave. This ensures that the foil is moved with the same force at every point. So, as the foil moves away from one stator and the force decreases, the foil moves closer to the other stator and the force increases.

[0010] Previously it was the other way around: the rear stator had to attract the foil, while the front one had to repel it to generate this negative half-wave.

[0011] An embodiment of the invention is described with reference to Fig. 1 to 4 explained.

[0012] They show: Fig. 1 the horizontal section through the loudspeaker looking at the base plate. Fig. 2 the connection principle. Fig. 3 sine wave Fig. 4 Functional principle List of reference symbols 1 stator row front 2 stator row rear 3 Rotatable tube for film attachment 4 slides 5 foil winding 6 Audio connection 7 High-voltage power supply with series resistor 8 transformers 9 Sine wave 10 Base plate 11 Identification frames 12 Cover plate (like base plate) QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 3118239 C1

[0003] US 000007054456B2

[0004]

Claims

[1] Electrostatic loudspeaker, characterized by , that two rows of round, oval or drop-shaped conductive stators (external electrodes) (1 and 2) are fastened or fixed in a base and cover plate (12 and 10). These have a uniform and thin insulating layer on the outside with a high dielectric strength against electrical voltage. The arrangement of the front row is spaced according to the diameter of the stators (1 and 2) and the intended use (frequency range to be radiated). The rear row of stators (2) is offset, placed between two stators (1) of the front row, whereby the diameter of the stators (1 and 2) and the desired frequency range determine the distance to the two front stators (1). A thin conductive foil (4) or one made conductive by coating is wound around these stators (1 and 2) in a wave-like manner and is not taut. [2] Electrostatic loudspeaker according to claim 1, characterized by The ends of the foil (4) are wound (5) onto two tubes or rods (3) that are rotatably mounted in the base and cover plates (10 and 12). This allows the foil length (4) and thus the distance to the stators (1 and 2) to be precisely determined, allowing everything to be changed or loosened. [3] Electrostatic loudspeaker according to claim 1 and 2, characterized by that despite the smallest dimensions there is a large membrane surface (4) which is driven electrostatically evenly and over its entire surface, thus creating a large stroke, with a constant radiation width and constant radiation height. [4] Electrostatic loudspeaker according to claim 1 to 3, characterized bythat the stators (1 and 2) are installed in a horizontally outwardly curved radius that is favorable for sound radiation. [5] Electrostatic loudspeaker according to claim 1 to 4, characterized by that the electrostatic drive consists of an inverted push-pull principle. [6] Electrostatic loudspeaker according to claims 1 to 5, characterized by that open operation is possible. [7] Electrostatic loudspeaker according to claims 1 to 5, characterized by that it can be installed in a housing that is open at the back to prevent acoustic short circuits. [8] Electrostatic loudspeaker according to claims 1 to 5 and 7, characterized by that rear sound attenuation can be achieved. [9] Electrostatic loudspeaker according to claim 1 and 5, characterized by that the stators (1 and 2) can be installed in a circle and thus form a sound column with a 360° radiation characteristic. [10] Electrostatic loudspeaker according to claims 1 to 5, characterized by that it can be installed in a baffle. [11] Electrostatic loudspeaker according to claims 1 to 7 and 9 and 10, characterized by that different frequency ranges can be transmitted via a loudspeaker by controlling stators (1 and 2) in different areas with a foil (4).

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