FOCUS CONTROL SIGNAL DETECTING SYSTEM OF OPTICAL DISK DEVICE,申请号JP19840270008-传众专利搜索

FOCUS CONTROL SIGNAL DETECTING SYSTEM OF OPTICAL DISK DEVICE

申请公布号：JPS61148632(A)

申请号：JP19840270008

申请日期：1984.12.20

申请公布日期：1986.07.07

申请人：

FUJITSU LTD

发明人：ARAI SHIGERU

分类号：G02B7/28;G11B7/09

主分类号：G02B7/28

摘要：PURPOSE:To obtain a system suitable to reduce weight easy to adjust optical system and able to obtain highly stable focus controlling signals by utilizing characteristic of differential output of a split type light detector that changes linearly corresponding to defocus distance of light beam spot. CONSTITUTION:The center axis of reflected luminous flux of diameter phi that enters parallel to the optic axis t of a light receiving lens 9 is shifted by necessary amount to the optic axis t, and when the diameter phi becomes large, overflowed part 19 from the edge of the light receiving lens 9 increases. Reflected luminous flux that passed through the light receiving lens 9 is converged and projected to a light detector 10'' of bisected type. In the figure of the bisected type light detector 10'', (u) and (v) denote output of left and right respectively. Position of the light detector 10'' is adjusted precisely and fixed on a plane perpendicular to the optic axis to make the value of differential output (u-v) zero when the position of an objective lens 6 is at focused position Lo. Then, v becomes larger than u by the effect of vignetting of the reflected luminous flux by the edge of the light receiving lens 9, and diameter phi of the reflected luminous flux becomes small. However, the center deviates to the left side and u becomes larger than v.