Magnetic fluid of loudspeaker
Magnetic fluid can reduce the working temperature of voice coil, improve the power bearing capacity of loudspeaker, improve the frequency response of loudspeaker, help the voice coil maintain the central position, reduce distortion and power compression effect, improve dynamic performance and prolong the service life of loudspeaker.
1. What is magnetic fluid
Magnetic fluid (also known as ferromagnetic fluid or magnetic fluid) is a brown black liquid magnet, which is formed by the uniform suspension of ultrafine magnetic particles with a diameter of about 10 nm in the synthetic oil carrier.
2. Brief history of magnetic fluid
Magnetic fluid came out with a mysterious color. It was once listed as a top secret. In order to solve the problem of liquid rocket fuel flow and accurate control in weightlessness, NASA has developed magneto-hydraulic technology in the implementation of space program.
Only after the solid fuel rocket technology was mature and replaced the liquid rocket did the magneto-hydraulic technology be lifted. Several scientists involved in the research of the project obtained special permission and established the magnetic fluid company in 1968 to continue to develop the civil technology of magnetic fluid. After more than 30 years of development,
Today, magnetic fluid has been widely used in speaker manufacturing, stepping motor, large power transformer, audio and video tape manufacturing, computer hard disk and floppy disk manufacturing and so on.
3. Effect of magnetic fluid
After adding a certain amount of magnetic fluid into the gap formed by T iron and Huawei of the loudspeaker, it will
Obviously improve the bearing power of the loudspeaker and prolong the service life of the loudspeaker. In general, the bearing power of the loudspeaker is limited by the heat resistance of the voice coil. The greater the power, the greater the heat generated, resulting in a sharp rise in voice coil temperature. When the bearing limit of voice coil material is reached,
The voice coil will be burned. The thermal conductivity of the magnetic fluid is much greater than that of the air. It can effectively dissipate the heat energy into the air through T iron, Huasi and basin frame, so as to prevent the voice coil from being burned, delay the aging of the voice coil material and binder, and prolong the service life of the loudspeaker.
Improve frequency response characteristics and reduce distortion. The magnetic fluid has certain damping, and the loudspeaker will have a peak on the frequency response curve near its lowest resonant frequency (F0), which will cause distortion due to the excessive amplitude of the diaphragm. This is a defect that speaker manufacturers want to overcome.
The frequency response curve of loudspeaker at F0 can be smoothed by using the damping effect of magnetic fluid with appropriate viscosity on voice coil motion. Thus, the frequency response characteristics are improved and the design of frequency divider circuit is simplified. The magnetic fluid has the function of central positioning, which can prevent the voice coil from rubbing when the amplitude is large.