Loudspeaker also known as "horn". Is a very common electroacoustic transducer parts, in the sound of electronic and electrical equipment can be seen in it. The loudspeaker is one of the weakest components in acoustics equipment, but for acoustics, it is one of the most important components. Although it is such a simple device, its development is not achieved overnight, but after a long time of research and countless people's painstaking efforts, gradually toward maturity and progress. The invention loudspeaker is in order to be able to let "original sound reproduce", although passed the effort of countless scientists, this goal has not been completely achieved up to now, it is different sound way instead, different manufacturing method and material use, make loudspeaker a hundred flowers bloom, become the most brilliant and brilliant garden in the sound world. The loudspeaker is divided into built-in loudspeaker and external loudspeaker. External loudspeaker is generally referred to as the speaker box, the built-in loudspeaker refers to the MP4 player has a built-in speaker. The kind of loudspeaker is very much, change energy principle to be able to divide for electric type (namely moving coil type), static electricity type (namely capacitor type), electromagnetic type (namely tongue spring type), piezoelectric type (namely crystal type) wait for a few kinds.
Electrodynamic loudspeaker
The electric loudspeaker is the loudspeaker prototype patent applied in January 20, 1874. In this loudspeaker, the voice coil with the support system is placed in a magnetic field to keep the vibration system in axial motion. At that time it was mainly used in the field of relays rather than loudspeakers. On December 14, 1877, Siemens applied for a patent for a bugle. On a moving voice coil, a parchment paper was attached as a sound radiator. The parchment paper could be made into an exponential cone shape, which was the solid shape of the bugle in the first phonograph era.
The basic principles of electric loudspeakers have not changed over the past few decades, only improved design details and components. Frequency response range dynamic range and other aspects of the older products have been a considerable development. Electric loudspeaker with simple structure, excellent sound quality, low cost, large dynamic has become the current market mainstream.
Electrostatic loudspeaker
Electrostatic loudspeaker is to use the electrostatic power added to the capacitor plate and the loudspeaker work, in terms of its structure, because the positive and negative poles are opposite and into the capacitor shape, so it is also called capacitor loudspeaker. Loudspeaker as an electroacoustic transducer, we have to start from the human understanding of electricity and sound conversion relations. Electromagnet sounds have been used since 1837 Page. But it was not until February 14, 1876, when Alexander Graham Bell filed one of the most important patents in history: the "telephone," an invention that allowed the human voice to travel farther than a shout. Since then, the conversion relationship between electricity and sound has been deeply rooted in the hearts of people, and more and more people have studied it.
In 1910, S. G. Brown separated the driving force from the diaphragm and developed the armature headset Armature for better playback of recorded sounds. In 1910, Baldwin developed balanced armature headphones. Armature headset is a movable iron plate (armature) in the middle of a U-shaped magnet. When the current flows through the coil, the armature will be magnetized and repulsed by the magnet, driving the diaphragm to move at the same time. In 1917, Wente and Thuras designed capacitive microphones. By the mid-1930s, electrostatic speakers were introduced, based on the principle of capacitive microphones.
Electrostatic monomer because of light weight and small vibration dispersion, so the electrostatic loudspeaker works in the middle and high frequency band, the sound quality is light and delicate, full of characteristics, it is easy to get clear and transparent medium and high pitch. But its efficiency is not high, the sound pressure output is low, the dynamic is small, the cost is relatively expensive also is its weakness.
Belt loudspeaker
During the gradual formation of the electric loudspeaker and electromagnetic loudspeaker technology, people began to understand that the ideal transducer should use a thin film that can vibrate through the current, and people began to conceive of the belt loudspeaker.
Belt loudspeaker is mainly used in the middle and high frequency band. Because of its flat frequency response curve, high frequency upper limit, it has a very good transient effect, so it can form a linear sound source conveniently.
Haier type loudspeaker is the fourth kind of radiation. It's a very elegant variant of the ribbon horn. It consists of printing aluminium film conductors up and down between two plastic films. Tortuous folds as accordion type, placed in a magnetic field perpendicular to the diaphragm, not made diaphragm all the same phase before and after the vibration, it is a horizontal direction perpendicular to the direction of the sound radiation and vibration and and adjacent conductors in the opposite direction to study the vibration of a corrugated, can know in the first half weeks into the creases between air by Mr. Figg (Fresnel, The Fresnel principle is released and the lower part of the fold widens, allowing air to enter, just as the ping-pong ball does not fly far when pressed in the hand, but can fly far when pressed up and down between the fingers and the ball pops out. In accordance with this principle, low (light) air, which is pushed back and forth at the diaphragm, can be blown away well according to Figg's principle. The diaphragm hour can be very efficient, but it is difficult to play back at low frequencies, with a low frequency limit of about 100Hz.