RU2496254C1 - Electric-arc loudspeaker - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: more than one step-up transformer is used, the secondary windings of which are parallel connected to electrodes, between which there created is high-voltage electric arc emitting sound vibrations by means of sound frequency amplifier and the commutator alternately distributing output voltage of amplifier to primary windings of transformers. With that, pulses of constant frequency and duration are obtained. During pulse action, transformer accumulates the energy proportional to output voltage of amplifier, which is transferred to arc at the interval between accumulation pulses. Pulses on primary windings of transformers are uniformly offset relative to each other within one carrier frequency period, have temporary ratios of energy accumulation and transfer, which correspond to number of used transformers. Besides, on arc electrodes there performed is series, alternate, amplitude-pulse modulation from each transformer, which improves accuracy of sound signal.

EFFECT: improving reproduction accuracy of sound signals.

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Description

The invention relates to electroacoustics, to sound emitters using a step-up transformer with a transmission coefficient of more than 1:50, to obtain a constant high-voltage arc discharge modulated by an audio signal.

From the prior art, devices for obtaining sound since plasma speakers and other emitters that use various types of modulation with an audio signal, which use a high-voltage arc discharge, which is independent both in appearance and in the method of its production and has characteristic differences from other discharges, such as corona and flare. (Physical Encyclopedic Dictionary. - M.: Soviet Encyclopedia. Editor-in-chief AM Prokhorov. 1983.)

It is also known that in order to ensure sound vibrations of minimal reproduction accuracy in the range of 20 Hz - 20 kHz, the carrier frequency creating an arc with any modulation should be at least two times higher than the upper limit of this range, i.e. at least 40 kHz. And for a more accurate sound (increase information content), the carrier frequency should be higher, two or more times. As a result, the resulting frequencies of 80 kHz and above go beyond the scope of the step-up transformer to create an electric arc and transmit to it an undistorted signal of a real, acceptable size with sufficient power, continuously working for an unlimited time. With a coefficient of more than 1:50 due to the high inductance of the boost winding.

The closest solution in technical essence is the device Pat No. CN 101820573 from 09/01/2010, where an electric arc is created by means of one step-up transformer with a transformation ratio of 1: 100, p. 10 of Fig. 3 and a control circuit is used that uses pulse-width modulation with an audio signal .

The disadvantage of this solution is that with pulse-width modulation, the spectrum of pulses transmitted by the transformer changes significantly. So, when the pulse duration is equal to half the repetition period, the high-frequency components are minimal and the longer the pulse duration differs from half the repetition period, the more high-frequency components in the spectrum. Thus, at the minimum and maximum pulse durations, the transformer bandwidth should be tens of megahertz even at a carrier frequency of 40 kHz, otherwise the shape of the transmitted pulses is significantly distorted and leads to unstable operation of the arc, cod, noise and its complete disappearance, which is not acceptable for receiving sound . Also, with this modulation, information changes once per period of the carrier frequency.

It is known that step-up high-voltage transformers have a very large inductance of the secondary windings and inter-turn capacitance, which significantly limits their bandwidth. It follows that, using a step-up transformer controlled by pulse-width modulation, it is not possible to get accurate sound.

The aim of the claimed invention is the creation of a radiator with high fidelity when listening.

This is achieved by the fact that the electric arc loudspeaker consists of more than one step-up transformer, the secondary windings of which are connected in parallel and connected to the electrodes, between which a high-voltage electric arc is emitted, emitting sound vibrations, using an audio frequency amplifier and a switch, which alternately distributes the output voltage of the amplifier to the primary transformer windings. In this case, pulses of constant frequency and duration with an amplitude equal to the output voltage of the amplifier are obtained. During the duration of the pulse, energy is accumulated in the transformer proportional to the output voltage of the amplifier, which is transferred between the accumulation pulses to the arc.

Since the energy transfer is carried out in reverse mode and is pulsed, the pulse transmitted to the arc can be considered discrete. That is, the pulse frequency can be talked about as the sampling frequency.

In the inventive loudspeaker, using the above-described switching, amplitude-pulse modulation of the arc current is carried out, in which the spectrum of discrete pulses transmitted by step-up transformers practically does not change, which ensures undistorted transmission of the modulating signal when step-up transformers with a coefficient of more than 1:50 are used even at operating frequencies near their upper bandwidth limits.

In addition, it must be added that, in relation to the claimed device, the higher the sampling frequency, the higher the accuracy (intelligibility, detail) of the emitted sound. To achieve this, in the inventive device uses more than one step-up transformer. They operate at the same, close to the limiting frequency, in turn with a shift, uniformly distributed within the same period of the carrier frequency with respect to each other, having certain ratios of accumulation and transmission pulses. At the same time, a sequence of discrete pulses from each one acts on the arc electrodes, also for one period, which contributes to increasing the sampling frequency (accuracy) of sound as many times as many step-up transformers are used in the device.

From this it follows that alternating switching of more than one transformer with the help of pulse-amplitude modulation allows you to transfer an undistorted sound signal into an electric arc and increase the accuracy (intelligibility) of the emitted sound.

Figure 1 shows a block diagram of the proposed loudspeaker.

The loudspeaker contains a clock generator 3, switch 2, connecting the primary windings, for example, in the variant of four transformers T1, T2, T3 and T4, to the amplifier 1, and their secondary boosting windings are connected in parallel and connected to the electrodes 4 and 5. An electric arc arises between them. emitting sound vibrations under the influence of a pulse current, the amplitude of which is modulated by the output voltage of the audio frequency amplifier 1.

The operation of the device is as follows. Under the influence of the control pulses of the clock generator 3, the switch 2 alternately commutates the primary windings of the transformers T1, T2, T3 and T4 so that they produce pulses of constant frequency and duration with an amplitude equal to the output voltage of the amplifier 1. Thus, the result is an amplitude-pulse modulation of the arc current by a sound signal. Transformers operate at the same frequency, in flyback mode, while the high inductance of the parallel connected secondary windings of step-up transformers in the energy storage mode does not affect the arc current pulse generated by the transformer in transmission mode. The pulses on the windings of the individual transformers are uniformly shifted relative to each other within the same period of the carrier frequency, having certain ratios of the accumulation and transmission pulses (figure 2). At the same time, a sequence of discrete pulses from each transformer in the same period acts on the arc electrodes, which is equivalent to increasing the sampling frequency of sound as many times as many transformers are used in the device.

The switch can be made in any way, taking into account the number of step-up transformers. Providing a direct connection and disconnection of each of the primary windings to the output voltage of the amplifier and necessary, including for the implementation of amplitude-pulse modulation, its distribution between the windings in the manner described above. For example, using powerful switching keys on field-effect transistors as switching elements.

The frequency of the clock generator is chosen so as to ensure the frequency of the pulses on each primary winding slightly below the upper limit of the transmission frequency of the applied step-up transformers, to ensure minimal distortion of the transmitted discrete pulses.

As an audio frequency amplifier, it is preferable to use a class D pulse amplifier, since such amplifiers have good load capacity, resistance to pulse loads, high efficiency and low heat dissipation.

Claims (1)

An electric arc loudspeaker containing an electronic control circuit of step-up transformers to create a high-voltage electric arc between the electrodes, modulated by a sound electric signal located at a certain distance between them, characterized in that more than one step-up transformer is used, the step-up secondary windings of which are connected in parallel and connected to the electrodes, and the primary windings are switched in such a way as to obtain current pulses, following each other from each step-up transformer of a high voltage across the arc and the amplitude-modulated pulsed manner.

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