MDCP: Patent Abstact US05737297: Optical head

US05737297 Optical head

Assignee Sharp Corporation

Assign./Filed April 7, 1998/ Feb. 11, 1997

Inventors Mashiyama; Tomio, Katayama; Hiroshi, Ogata; Nobuo, Ikeda; Kenji

Summary Improved MD optical head.

Abstract A light radiated from a light source is divided by a grating into a main beam for detecting information signals and sub-beams for tracking, and thus irradiates a mini disk. The beams reflected by the mini disk are converged through a concave cylindrical mirror on a second light detector composed of adjacently disposed divided light receiving elements H (light receiving parts A and B) and J (light receiving parts C and D) and light receiving elements E1, F1, E2 and F2. The concave cylindrical mirror shapes the reflected beams so that spots of the reflected beams converged on the second light detector take elliptic shapes that are flattened in a direction in which the main beam for detecting the information signals and the sub-beams for tracking are arranged. In this manner, reliability of an optical head can be improved without increasing the size of the light receiving elements and without causing interference between a main spot and sub-spots.

US05737297	Optical head
Assignee	Sharp Corporation
Assign./Filed	April 7, 1998/ Feb. 11, 1997
Inventors	Mashiyama; Tomio, Katayama; Hiroshi, Ogata; Nobuo, Ikeda; Kenji
Summary	Improved MD optical head.
Abstract	A light radiated from a light source is divided by a grating into a main beam for detecting information signals and sub-beams for tracking, and thus irradiates a mini disk. The beams reflected by the mini disk are converged through a concave cylindrical mirror on a second light detector composed of adjacently disposed divided light receiving elements H (light receiving parts A and B) and J (light receiving parts C and D) and light receiving elements E1, F1, E2 and F2. The concave cylindrical mirror shapes the reflected beams so that spots of the reflected beams converged on the second light detector take elliptic shapes that are flattened in a direction in which the main beam for detecting the information signals and the sub-beams for tracking are arranged. In this manner, reliability of an optical head can be improved without increasing the size of the light receiving elements and without causing interference between a main spot and sub-spots.