| 摘要 |
PURPOSE:To increase the resonance frequency of a magnetic yoke and to miniaturize a device, by constituting the device in such a way that a part of the projecting part of the yoke is inserted to a recessed part opened downward underneath the center part of a bobbin. CONSTITUTION:An inner yoke 14a inserted to the recessed part 11a directing downward provided underneath the bobbin 11 after forming the center of the magnetic yoke 14 of an objective lens driving device used for the pickup of an optical disk in a projecting shape is formed cylindrically, and a through hole 16 for an optical path is provided almost in the center part of the yoke. Magnetic flux outputted from magnets 15a and 15b cross coils 13a-13c, and a magnetic circuit closed in the inner yoke 14a is formed. In such a way, it is possible to increase the resonance frequency of the inner yoke, and to miniaturize the device because the thickness of a cylinder can be thinned.
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