Abstract: An anode active material for a lithium secondary battery includes a carbon-based particle including pores therein, a silicon-containing coating layer formed at an inside the pores of the carbon-based particle or on a surface of the carbon-based particle, and a carbon coating layer formed on the silicon-containing coating layer. A full width at half maximum (FWHM) of an O1s peak of a surface measured by an X-ray photoelectron spectroscopy (XPS) is 2.0 or more. A lithium secondary battery including the anode active material having improved initial discharge capacity and capacity efficiency is provided.

Abstract: In the electric-acoustic transducer, first to third permanent magnets are respectively received in the first to the third recesses of a yoke, so as to generate non-alternating magnetic fields. The first and second magnetic gaps are formed between the yoke and the first and the second plates. The first and the second coils are respectively disposed in the first and the second magnetic gaps, to generate alternating magnetic fields of the same phase, when an electric driving signal is applied from the exterior. The electric-acoustic transducer achieves reproduction of a broad frequency band with high power and high efficiency, even with an ultra slim or small dimension, proper for a small electronic appliance such as a notebook computer, by employing dual voice coil drivers and auxiliary magnetic circuits.

Abstract: Disclosed is an electric-acoustic transducer comprising at least one fixed coil adapted to generate alternating magnetic field upon externally receiving an electrical drive signal, a frame having a recessed structure for centrally receiving and supporting the fixed coil, at least one moving permanent magnet disposed over the fixed coil while being spaced from the fixed coil by a desired vertical distance in such a fashion that it is vertically movable, the moving permanent magnet serving to generate non-alternating magnetic field, and a vibrating diaphragm supported by an upper end of the frame at a peripheral portion thereof, the vibrating diaphragm supporting the permanent magnet by a central portion thereof, whereby the vibrating diaphragm vibrates vertically in accordance with an interaction between the alternating magnetic field generated from the fixed coil and the non-alternating magnetic field generated from the permanent magnet.

Abstract: An electro-acoustic micro-transducer having a high power, high efficiency acoustic transducing feature and a three-mode broad band frequency reproduction feature on a micro-scale basis is provided. The electro-acoustic micro-transducer includes a yoke formed of an internal groove and a vertical incision portion for removing a vertical wall at one side surface, a permanent magnet installed in the groove of the yoke, a plate for forming a magnetic gap, a coil wound on the bobbin, a frame which surrounds the yoke, in which a throughhole is formed in the groove corresponding to the incision portion of the yoke, and a vibration diaphragm. Therefor, spaces in the incision portion of the yoke and the frame are formed so that a connection portion between the coil and lead wire can be prevented from contacting the yoke during vertical vibration, to thereby extend an up-and-down vibration width of the bobbin.