1. Field of the Invention
The present invention relates to an improved structure of a speaker, and more particularly, to a speaker structure which can effectively reduce a sound distortion by smoother excursion.
2. Description of the Prior Art
The operation principle of a speaker is based on the Fleming's left hand rule, wherein an electrified voice coil is placed in a magnetic field and driven by the reactive force to generate movement, thereby driving a vibrating plate to yield sound energy by causing the air to move. Therefore, the speaker is an audio device which can convert an electrical signal into mechanical energy to let the air move. To be precise, the operation of the speaker is to convert an audio-frequency electrical signal with a certain frequency range into a low-distortion and audible sound with enough sound pressure level.
The moving coil type of speakers is commonly used presently. A moving coil speaker comprises a magnetic circuit module including permanent magnetic, core pole piece and magnetic top plate; a moving module including cone membrane, suspension surround, voice coil; and a supporting module including spider, cone frame, gasket pad, wherein the voice coil is fixed to the diaphragm. When an audio-frequency electrical signal is coupled with the voice coil, the wire-wound cylindrical voice coil in the permanent magnetic field is connected with the diaphragm. Driven by the electrical signal, the voice coil and the diaphragm connected to the voice coil move together and then generate sounds.
The major difference between the moving coil speaker and other speakers is in the diaphragm. The edge of diaphragm is usually fixed to an elastic medium including surround and spider. For example, in a large-size woofer unit, the diaphragm is usually in cone shape and is vibrated with the elastic medium. From
Therefore, the traditional structure of speakers presents some shortcomings to be overcome.
In view of the above-described deficiencies of the traditional structure of speakers, after years of constant efforts in research, the inventor of this invention has consequently developed and proposed an improved structure of a speaker.
It is an object of the present invention to provide an improved structure of a speaker which helps a diaphragm of the speaker move more smoothly with less resistance and reduces a distortion of sounds when a voice coil of the speaker moves.
The improved structure of the speaker comprises a cone frame and a moving module, wherein the moving module is connected with the cone frame, and the moving module comprises a surround and a diaphragm. A circumference of the diaphragm is sealed to an edge of an opening of the cone frame. A container portion is disposed on an inner side of the opening of the cone frame, and the surround is vertically connected with the diaphragm and the container portion of the cone frame. Therefore, when an audio-frequency electrical signal is coupled with a voice coil inside the cone frame, the voice coil moves to drive the diaphragm to move and generate a sound. The present invention uses the surround to reduce the resistance of the diaphragm excursion, which helps the diaphragm move more smoothly and reduces a distortion of the sound while compared with the conventional structure.
Please refer to
When an audio-frequency electrical signal is coupled with the voice coil inside the cone frame 4, the voice coil moves and then drives the diaphragm 52 to move and generate sounds. In the present invention, when the voice coil moves, the surround 51 helps the diaphragm 52 move more smoothly with less resistance and reduces a sound distortion while compared with the traditional structure.
Please refer to
From
In addition to the advantage described above, the present invention further limits the size of the cone frame to achieve the maximum effective moving area (Sd) to provide the best sound pressure efficiency, which is calculated as below:
Vas is an equivalent air volume of the speaker. Sd is an effective moving area. Cms is a compliance of the suspension system. Qes is an electric damping factor. η0 is an efficiency of the speaker unit. Re is a DC resistance of the voice coil. BL is a force factor contributed by the magnetic circuit and the wire lengths of the voice coil. Mms is a moving mass of the speaker including the air load. Msurround is a surround mass of the surround. Mvc is a voice coil mass. Mbond is a bond mass for the moving part, and Fs is a resonance of the speaker unit. Besides, the Mms for the traditional speaker is calculated as:
In the present invention, the moving mass of the speaker (Mms) including the air load is calculated as:
M
ms
=M
cone+cap
+M
vc
+M
Bond
Therefore, the present invention can ignore the surround mass of the surround (Msurround) and achieve the maximum sound pressure efficiency of the speaker unit with the same size of that of the traditional speaker.
The present invention provides an improved structure of a speaker, while comparing with other prior art techniques, is advantageous in:
Many changes and modifications in the above described embodiment of the invention can, of course, be carried out without departing from the scope thereof. Accordingly, to promote the progress in science and the useful arts, the invention is disclosed and is intended to be limited only by the scope of the appended claims.