Industrial Technology Research Institute

Kun-Lung Yen

Dar-Ming Chiang

A magnetic circuit applied for loudspeakers includes a cup-shaped yoke, a primary magnet, a surrounding top plate, a first central top plate, and a thin magnet. The cup-shaped yoke includes a bottom part and a ring part. The primary magnet is located within the bottom part of the yoke and serves as a magnetic field source. The surrounding top plate and the first central top plate are respectively located on the ring part of the yoke and the primary magnet. A air gap between the surrounding top plate and the first central top plate is formed and used for accommodating a voice coil, which may actuate a diaphragm to emit sound. The thin magnet is located on the first central top plate and repels the primary magnet magnetically. Therefore, the magnetic leakage above the air gap can be strongly reduced. In addition, an additional second central top plate is mounted on the thin magnet and may serve as magnetic shielding.

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Kun-Lung Yen