A micro-speaker is disclosed. The micro-speaker includes a frame, a magnetic circuit unit in the frame, a first vibration unit, and a second vibration unit. The magnetic circuit unit forms a first volume cooperatively with the first vibration unit, and a second volume cooperatively with the second vibration unit. The magnetic circuit unit further includes an aperture for communicating the first volume with the second volume for enabling the first vibration unit in phase with the second vibration unit.

FIELD OF THE INVENTION

The present invention relates to electroacoustic apparatuses, more particularly to a micro-speaker used in an electronic device for converting electrical signals to audible sounds.

DESCRIPTION OF RELATED ART

Sound which can be heard by a person's auditory sense is transmitted in the form of waves. The sound having the wave form moves air molecules and vibrates the tympanic membrane, thus allowing a person to hear the sound. In order to provide audible sounds, various kinds of micro-speakers have been developed. An micro-speaker is generally coupled to an audio equipment or an amplifier for use as a large sound producing means for considerably amplifying volume. Alternatively, the micro-speaker may be used as a small sound producing means having a small size and volume.

An electronic device, such as a cellular phone, a camcorder, a PDA, a digital camera, or a notebook computer, provides a space for accommodating a micro-speaker therein. Nowadays, a micro-speaker with high quality audio performance and miniature size is desired.

A typical micro-speaker related to the present disclosure includes a vibration unit having a diaphragm, a magnetic circuit unit having a magnet, and a housing for receiving the vibration unit and the magnetic circuit unit therein. For improving the low frequency sound performance, this kind of micro-speaker generally provides a diaphragm or a magnet having relatively greater weight. Or, the micro-speaker includes two speaker units having the same configurations. Diaphragm having greater weight, however, will result in unbalanced vibration which will badly affect the sound quality. Larger magnet or two speaker units will increase the volume of the micro-speaker.

Accordingly, an improved micro-speaker which can overcome the disadvantages described above is desired.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT

The present invention will hereinafter be described in detail with reference to an exemplary embodiment.

Referring toFIG. 1which is an isometric and exploded view of a micro-speaker1oin accordance with an exemplary embodiment of the present disclosure, the micro-speaker10is used in an electrical device such as a notebook, a mobile phone, a portable consumer device for converting electrical signals to audible sounds. The micro-speaker10includes a frame11, a magnetic circuit unit12positioned by the frame11, a first vibration unit13supported by the frame11, a second vibration unit14supported by the frame11, and a cover15engaging with the frame11for forming a housing. The first and second vibration units13,14interacts with the magnetic circuit unit12for producing sounds by means of vibrations. The first vibration unit13includes a first diaphragm131and a first voice coil132directly or indirectly connecting with the first diaphragm131. Similarly, the second vibration unit14includes a second diaphragm141and a second voice coil142directly or indirectly connecting with the second diaphragm141. When electrified, the first and second voice coils132,142drive the first and second diaphragms131,141to vibrate for generating audible sounds due to Lorenz Force produced by the interaction between the voice coils and the magnetic circuit unit12.

Referring toFIG. 2, an exploded view of the magnetic circuit unit12, the magnetic circuit unit12includes a yoke121made of magnetic conduct material, a first magnet assembly122coupled with the yoke121, and a second magnet assembly123couple with the yoke121. The first magnet assembly122comprises a permanent magnet and a pole plate attached to the permanent magnet, or comprises a permanent magnet without a pole plate attached thereto. Similarly, the second magnet assembly123comprises a permanent magnet and a pole plate attached to the permanent magnet, or comprises a permanent magnet without a pole plate attached thereto. In this embodiment, the second magnet assembly123comprises four separated parts. In fact, alternatively, the second magnet assembly123may be a single ring. The yoke121comprises a bottom121a, a plurality of sidewalls121bextending upwardly from peripheries of the bottom121a, and a plurality of flanges121cextending perpendicularly from the sidewalls121balong a direction away from a center of the bottom121a. Thus, the flanges121care parallel to but not overlap with the bottom121a. Further, the sidewall121bdefines a plurality of apertures121dtherethrough.FIG. 2shows that each of the sidewalls121bdefines a plurality of apertures121d. In fact, only selected sidewalls121binclude the apertures121d, and other sidewalls121bdo not include the apertures121d. Another word, at least one of the sidewalls121bincludes at least one aperture121d.

Referring toFIG. 3, an assembled view of the magnetic circuit unit12, the first magnet assembly122locates on the bottom121aof the yoke121, with an outer surface thereof keeping a distance from the sidewalls121bof the yoke, for forming a first magnetic gap121ebetween the outer surface of the first magnet assembly122and the sidewalls121b.

Referring toFIG. 4that is an assembled view of the magnetic circuit unit12from another aspect opposite toFIG. 3, the second magnet assembly123locates on the flanges121cwith an inner surface thereof keeping a distance from the sidewall121bfor forming a second magnetic gap121f. By virtue of the configuration described above, the first and second magnet assemblies122,123define two magnetic gaps121e,121fformed at two opposite sides of the yoke121, and the sidewall121bis a common component for forming the two magnetic gaps.

Referring toFIGS. 5-7, when assembled, the cover15engages with the frame11for providing the housing to accommodate the magnetic circuit, the vibration units therein. The frame11includes an inner rib111extending toward a center thereof for abutting against the flanges121cof the yoke to position the yoke in the frame11. An edge of the first diaphragm131attaches to an upper surface of the frame11, and an edge of the second diaphragm141attaches to a lower surface of the frame11. The first voice coil132suspends in the first magnetic gap121ewith one end thereof connected to the first diaphragm131. The second voice coil142suspends in the second magnetic gap121fwith one end thereof connected to the second diaphragm141. A first volume20is formed between the first diaphragm131and the yoke121and the first volume20is communicated with the first magnetic gap121e. A second volume30is accordingly formed between the yoke121and the second diaphragm141, and the second volume30is communicated with the second magnetic gap121f. Optionally, a part of the second magnet assembly123locates on the flange121cof the yoke121, and another part of the second magnet assembly123locates on the inner rib111of the frame11, thereby increasing the distance between the inner surface of the second magnet assembly123and the sidewall121b. In addition, by virtue of the second magnet assembly123which is contemporary attached to the flange121cand the inner rib111, the frame11and the magnetic circuit unit can be coupled to each other firmly.

Referring toFIG. 7, the first volume20is separated from the second volume30by the yoke121, but is communicated with each other via the aperture121ddefined in the sidewall of the yoke121. When the first diaphragm131moves downwardly due to the Lorenz Force produced by the first voice coil132, the air in the first volume20will be pressed and leak into the second volume30via the aperture121dthereby pushing the second diaphragm141to move downwardly. Thus, the first and second diaphragms move in a same direction. Similarly, when the first diaphragm131move upwardly, the first volume20will be enlarged and the air in the second volume30will flow into the first volume20thereby forcing the second diaphragm141to move upwardly. The same situation will accordingly occur when the second diaphragm move initiatively. Synchronous movements of the first and second diaphragms along the same direction will effectively enhance the low frequency sound quality. Alternatively, the first and second voice coils may be electrified by one electrical signal contemporarily.