| 摘要 |
PURPOSE:To detect surely record discs different in size by arranging light emitting element systems and photodetector systems in positions corresponding to sizes of record discs on a turntable through light guiding optical fiber glasses. CONSTITUTION:End faces of optical fiber glasses 11a and 11b are arranged on one line in the diametral direction of a turntable 1, and end faces of optical fiber glasses 12a and 12b for light reception are aligned in the diametral direction of the turntable 1, and these lines make an angle theta so that end faces of optical fiber glasses 11a and 11b and optical fiber glasses 12a and 12b do not overlap. When an LP disc 3a is placed on the turntable 1, a reflective face is formed on light projecting and receiving holes 8a and 8b, and therefore, light projecting and receiving holes 8a and 8b and the first and the second light guiding and receiving slits 9a, 9b, 10a, and 10c lead the light of a light emitting element 4 to a photodetector 7 through optical fiber glasses 11a, 11b, 12a, and 12b. When an EP disc 3b is placed on the turntable 1, the reflective face on the light projecting and receiving hole 8a does not exist, and therefore, the light from the light emitting element 4 does not reach the photodetector 7. |
