Electrostatic speaker:
In order to better tell the story of human electroacoustic history, let's start with the first "telephone" that transmits human voice to a distant place. 100 years ago in February 1876, Alexander Graham Bell put forward the most important patent "telephone" in history. This invention makes human voice spread farther than shouting, and human beings understand the conversion relationship between sound and electricity from now on, and enjoy it.
In order to play back the recorded sound better, in 19 10, S. G. Brown separated the driving force from the diaphragm and invented the armature earphone.
Balanced armature earphone:
19 10, Baldwin invented the balanced armature earphone. Armature earphone is a movable iron plate (armature) installed in the middle of U-shaped magnet. When current flows through the coil, the armature will be magnetized, and the magnets will repel each other and drive the diaphragm to move. This design cost is low, although the effect is not good, but it was also an epoch-making invention at that time. This technology is mostly used in telephone handsets and small headphones.
In the mid-1930s, according to the principle of condenser microphone, electrostatic speaker appeared. In the early 1950s, American C. V. Bocciarelli put forward the law of "constant charge". P. Walker independently developed the same theory in the same period and applied it to the design of the famous Quad electrostatic speaker.