CN112866887A

CN112866887A - Microwave plasma loudspeaking method

Info

Publication number: CN112866887A
Application number: CN202110013967.3A
Authority: CN
Inventors: 傅文杰; 黎晓云; 韩中昱
Original assignee: Chengdu Yijie Technology Co ltd
Current assignee: Chengdu Yijie Technology Co ltd
Priority date: 2017-11-20
Filing date: 2017-11-20
Publication date: 2021-05-28
Also published as: CN107948895A

Abstract

A microwave plasma loudspeaking method relates to microwave excited plasma and plasma sounding technology. The invention comprises the following steps: 1) the audio signal is modulated by pulse width to be a pulse voltage signal; it is characterized by also comprising the following steps: 2) loading a pulse voltage signal to a microwave source to generate a microwave pulse, and 3) ionizing neutral gas by the microwave pulse, wherein in the process of breaking down the gas, an audio signal in the microwave is changed into a frequency audible to human ears, so that the loudspeaker is realized. The invention has the characteristics of high power, good low-frequency sound effect, small breakdown loss and high efficiency when the microwave excites the plasma.

Description

Microwave plasma loudspeaking method

This application is a divisional application to the following patent applications:

application No.: 201711153493.2

Application date: 2017.11.20

The invention name is as follows: microwave plasma loudspeaker

Technical Field

The invention relates to a microwave excited plasma and a plasma sounding technology.

Background

In 1951, Siegfried Klein introduced plasma tweeter unit based products in paris, which were quite expensive. Because of the immaturity of the product in use, it was known to be in the wrong luck before the appearance. Later in the 60's of the 20 th century, an engineer called Faulkus redesigned it and finally completed commercialization in 1968. The plasma loudspeaker is a special loudspeaker completely different from a common loudspeaker, the common loudspeaker drives air to produce sound through vibration of a vibrating diaphragm, the vibrating diaphragm produces sound essentially by forced vibration, and the vibrating diaphragm is a mechanical structure with restoring force and quality, so that a problem can exist: the existence of resonance frequency inevitably generates frequency spectrum distortion, and the resonance problem must be solved for the first time in order to fundamentally improve the sound production performance of a common loudspeaker. Therefore, the plasma speaker is produced by directly driving ionized air to vibrate and produce sound, so that the plasma speaker theoretically restores the true timbre of the sound to the maximum extent. At present, most plasma loudspeakers ionize air by high-voltage discharge, and the current in an electric arc is controlled by an audio signal to generate corresponding sound waves. The microwave excited plasma loudspeaker provides a new technology for the existing ion loudspeaker.

The traditional plasma loudspeaker adopts the technical scheme that air is ionized by high-voltage discharge, arc discharge can be generated in the ionization process, the diameter of the cross section of an arc is in direct proportion to the magnitude of current in the arc, the thickness degree is different from the air expansion degree, and corresponding sound waves are generated by controlling the magnitude of the current in the arc through audio signals. The disadvantages are as follows: the plasma speaker has many limitations in its application due to low power, large breakdown air loss when plasma is generated, and low efficiency.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a microwave-excited plasma loudspeaking method with better frequency response characteristics.

The technical scheme adopted by the invention for solving the technical problems is that the microwave plasma loudspeaking method comprises the following steps:

1) the audio signal is modulated by pulse width to be a pulse voltage signal; it is characterized by also comprising the following steps:

2) loading a pulse voltage signal to a microwave source to generate microwave pulses,

3) the neutral gas is ionized by the microwave pulse, and in the process of breaking down the gas, the audio signal in the microwave is changed into the frequency audible to human ears, so that the loudspeaker is realized.

The invention also provides a microwave plasma loudspeaker which is characterized by comprising a rectangular waveguide, wherein one end of the rectangular waveguide is provided with a microwave source, the other end of the rectangular waveguide is provided with a plasma generator and a short-circuit piston, and the rectangular waveguide is also provided with a microwave reflection power allocation device.

The microwave source is a magnetron and is coupled to the rectangular waveguide through a through hole formed in one wide side of the rectangular waveguide, and the end face of the rectangular waveguide is closed.

Or the microwave source is arranged on the end face of the rectangular waveguide.

The plasma generator comprises a circular inner tube penetrating through two wide sides of the rectangular waveguide and a circular outer tube arranged on the outer wall of one wide side of the rectangular waveguide, and one part of the circular inner tube is positioned inside the circular outer tube. The axis of the circular inner tube is superposed with the axis of the circular outer tube and is perpendicular to the wide side of the rectangular waveguide, and the intersection point of the axis of the circular inner tube and the wide side of the rectangular waveguide is positioned on the middle line of the wide side of the rectangular waveguide. The short-circuit piston is arranged at the end part of the rectangular waveguide. The microwave reflection power adjusting device is 3 pins which are arranged in parallel along the central line of the wide side of the rectangular waveguide.

The microwave source circuit also comprises a modulation module, wherein the modulation module is provided with an audio signal input end and a pulse signal output end, and the pulse signal output end is in circuit connection with the microwave source.

The invention has the beneficial effects that: high power, good frequency response characteristic, low breakdown gas loss and high efficiency.

Drawings

Fig. 1 is a schematic diagram of the whole system of a microwave plasma loudspeaker.

Fig. 2 is a schematic diagram of the working process of a microwave plasma loudspeaker.

Fig. 3 is a pulse width modulated audio waveform.

Fig. 4 is a cross-sectional view of the plasma generator.

Fig. 5 is a top view of the plasma generator.

In the figure, 11 microwave sources, 12 tuners, 13 plasma generators, 14 waveguides, 15 flanges, 16 flanges, 41 flanges, 42 outer tubes, 43 gas inlets, 44 inner tubes, 45 short-circuiting pistons.

Detailed Description

See fig. 1-4.

The principle of the invention is that the audio signal is modulated into a pulse voltage signal by pulse width modulation. The pulse voltage signal is loaded on the microwave source to generate a microwave pulse signal, and the microwave pulse signal passes through the tuner and the plasma excitation device, and the microwave electric field accelerates electrons to ionize neutral gas, so that plasma is generated. During the breakdown of the gas, the audio signal in the microwave becomes audible to the human ear, thereby achieving a speaker effect.

Further, the microwave plasma generating device comprises four parts: the device comprises an audio signal modulation device, a microwave source, a microwave adjusting device and a plasma generating device. See fig. 1.

The microwave source is a device for generating microwaves, and the audio signal needs to be modulated into a pulse signal so as to be loaded into the microwaves. The audio signal modulation device modulates an audio signal into a pulse signal, mainly is a pulse width modulation device, obtains a series of pulses with different pulse widths by controlling the on-off of a microwave source working power supply, and replaces the waveform of the audio signal with the pulses. Microwave with audio signal enters into plasma generator through the adjusting device and the waveguide coaxial converter, and then ionizes neutral gas to generate plasma for sounding. The operation is shown in fig. 2.

FIG. 1 is a schematic diagram of an overall system according to an embodiment of the present invention. Fig. 2 is a schematic workflow diagram of an embodiment of the present invention. The audio signal is pulse width modulated by the modulation module to generate pulse waveforms with different pulse widths as shown in fig. 3.

In this embodiment, the microwave source is a magnetron having an operating frequency of 2450MHz and a peak power of 4000 kW. The voltage pulse signal output by the modulation module is loaded on a power supply of the magnetron, so that the magnetron works in a pulse mode to generate a microwave signal output in a pulse mode.

In this embodiment, the microwave generated by the magnetron is transmitted to the tuner through a BJ26 rectangular waveguide. In the embodiment, a three-pin tuner is used, the microwave reflection power is controlled mainly by adjusting the depth of the pins, and the optimal microwave transmission matching of the system is ensured when the standing wave coefficient of the plasma load is changed in a large range. The microwave is connected into the plasma generator after passing through the tuner.

In this embodiment, the plasma generator is a waveguide coaxial structure, and its cross-sectional view is shown in fig. 4 and its top view is shown in fig. 5. The structure is characterized in that a round hole with the diameter of 40mm is formed in the wide side of the rectangular waveguide, the round hole is connected with a round outer pipe with the inner diameter being the same as the diameter of the round hole, another concentric hollow round inner pipe is arranged in the center of the outer pipe, and the outer diameter of the inner pipe is 10mm and the inner diameter of the inner pipe is 5 mm. The inner tube is connected with the bottom of the waveguide, the bottom of the inner tube is provided with an air inlet, and high-pressure air enters the inner tube through the air tube and is sprayed out from the top of the inner tube. The microwave enters between the outer pipe and the inner pipe from the BJ26 waveguide through the waveguide coaxial structure, and a short-circuit piston is arranged at the bottom of the rectangular waveguide and used for adjusting the intensity of the microwave field entering the coaxial structure from the waveguide. The microwave ionizes the gas ejected from the inner tube at the top of the coaxial structure to form plasma. Because the modulated audio signal is carried in the microwave, the plasma generates an audible audio signal for human ears when breaking through air, thereby achieving the effect of making sound.

Claims

1. The microwave plasma loudspeaking method comprises the following steps:

2. A microwave plasma speaker method as claimed in claim 1, wherein said step 3) comprises the steps of:

a. the microwave pulses are transmitted from the waveguide to the plasma generator, and the neutral gas is ionized by the microwave electric field, thereby generating plasma.

3. A microwave plasma amplifying method according to claim 2, wherein said waveguide is a rectangular waveguide, and said plasma generator includes a circular inner tube penetrating both broad sides of the rectangular waveguide, and a circular outer tube provided on an outer wall of one broad side of the rectangular waveguide, a part of the circular inner tube being located inside the circular outer tube.

4. A microwave plasma speaker method as claimed in claim 3, wherein the microwave source is disposed at one end of a rectangular waveguide, the other end of the rectangular waveguide is provided with a plasma generator and a short-circuiting piston, and the rectangular waveguide is further provided with a microwave reflection power adjusting device;