1. In order to obtain a vibrating membrane with a substantially constant charge distribution, a scheme of designing the vibrating membrane with semiconductor materials is proposed. Since semiconductor materials have the characteristics of significant changes (such as temperature, light) under the influence of external conditions, it is obviously not feasible to use them to make diaphragms. The design scheme of the diaphragm is: a synthetic diaphragm with a volume resistivity of 106 ~ 108ω·cm, a high-strength, flexible material.
2. The polarized power supply is omitted, and the diaphragm is made of electret material. Think of an electret as a polarized or charged diaphragm that does not require a separate polarizing voltage. However, experiments have shown that it is not suitable to use only electret materials to make the diaphragm. Another consideration is the use of polarized power supplies in the audio signal. This is based on the consideration that although the polarized diaphragm requires a high voltage, the required current is very small (≤10μA or so), and the power consumption is extremely small. The disadvantages of this scheme are: it inevitably increases the distortion; secondly, the structure tends to be complicated.
3. Mistakenly think that the horn-type speakers are easy to absorb dust. This is due to the phenomenon that there is a lot of electrostatic environment around us, and it is easy to collect dust. In fact, the condition of electrostatic precipitator is that static electricity must ionize the dust particles in order to adsorb the dust particles. But horn loudspeakers work under the condition of an alternating electric field. When the electric field strength exceeds a certain critical value, it is possible to ionize the dust and collect the dust. Under normal working conditions, its electric field strength is less than the above critical value. Therefore, dustproof is considered too much in the design.
4. It is believed that the horn-type loudspeaker is not suitable for higher sound pressure. Early electrostatic speakers did have this problem. The reason is that the diaphragm of the early horn loudspeaker is mostly made of metal material, which has low tensile strength and is easy to crack and damage under high sound pressure. In addition, the stationary electrodes of early horn speakers were poorly insulated. When the sound is played under high sound pressure, the amplitude of the movable electrode is large, and the insulating medium between the two electrodes is broken down by the high voltage, resulting in corona. With the advancement of the material industry, the use of polymer high-strength diaphragm materials in horn loudspeakers has become quite common. In addition, there is no problem in obtaining an insulating electrode plate material with a withstand voltage greater than 6KV. The actual measurement results show that the horn-type loudspeaker with a vibration area of 10000mm2 can stably output a sound pressure of 110dB for a long time.
