| 摘要 |
PURPOSE:To reduce the size and to decrease the number of parts by using an X axis driving permanent magnet and an X axis driving coil which applied a light beam to a target position on a disk surface by shifting an objective lens in coaction with said permanent magnet. CONSTITUTION:An information converting device 44 having the large mass and large volume is fixed at the outside of an outer box yoke 33. At the same time, a magnetic circuit which has the large mass and volume and drives an objective lens 32 toward a Z axis is provided at the fixed part of a carriage assembly. Furthermore a notch part 34 where a light beam 45 passes is used to form a part of the magnetic circuit. As a result, both the mass and volume can be extremely reduced for the variable part of the carriage assembly as well as this assembly as a whole. At the same time, the air gap of the magnetic circuit of an X axis direction drive source is also reduced and therefore the size of said magnetic circuit can also be reduced. Then the size of an X axis driving coil 38 can be reduced because the greater part of the coil 38 functions as a drive source which drives the variable part of the carriage assembly toward the X axis.
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