| 摘要 |
PURPOSE:To read accurately information through a lens with low performance by providing a flexible support member which links a base with a projection lens and is displaceable in three dimensions and an electromagnetic driving means which drives and controls the projection lens at right angles to the optical axis. CONSTITUTION:When the output of a detector 8 is applied to coils 103a-103c, forces generated by permanent magnets 104a and 104b in directions A and B operates on coils 103a and 103b on a lens barrel 102 supported by an elastic support member 107, so the projection lens 101 moves at right angles to and along an information track T. A force generated by a magnet 104c in a direction C operates on the coil 103c on an elevation member 108 supported by an elastic support member 109 fitted to the base 110 to move the projection lens 101 at right angles to the information track surface. Thus, the projection lens of simple constitution is moved in three dimensions to position a light spot at one point on the information track accurately, performing focusing. |
