| 摘要 |
<p>PCT No. PCT/JP87/00343 Sec. 371 Date Mar. 4, 1988 Sec. 102(e) Date Mar. 4, 1988 PCT Filed May 28, 1987 PCT Pub. No. WO88/00755 PCT Pub. Date Jan. 28, 1988.An optical disc in which distortion due to temperature change is inhibited has a magnetic positioning disc 3 of specified diameter mounted at the center of the disc substrate 1 having an information recording layer 2 on a specified radial area. The positioning disc is bonded to the disc substrate by an element(s) made of a material whose thermal expansion coefficient is almost equivalent to that of the disc substrate.</p> |
