| 摘要 |
PURPOSE:To make an accurate read of information through a lens with low performance by providing coil members fixed along the outer circumference of a holder which holds a projection lens, magnet members opposed to the coil members, and an elastic supporting boy for supporting a lens barrel. CONSTITUTION:When the output of a detector 8 is applied to cils 103a-103c, forces generated in the 1st and the 2nd directions A and B by permanent magnets 104a and 104b operate on the coils 103a and 103b on the lens barrel 102 supported by the elestic support member 107 to move the projection lens 101 at right angles to and along an information track T. A force generated in the 3rd direction C by a magnet 104c operates on the coil 103c on an elevation member 108 supported by the elastic support member 109 to move the projection lens 101 in the vertical direction. Thus, the projection lens of simple constitution is moved in three dimensions in a plane parallel to the information track to position a light spot at one point on an information track accurately, attaining focusing. |
