Patent ID: 6225638
Filing Date: 2001-05-01
Classification: G11B

Abstract:
A disc discrimination device provided with a disc apparatus loadable with a disc having a recording surface to reflect light and selected from a plurality of discs with different thicknesses, comprising:a light source disposed on one side of the recording surface and operative to obliquely irradiate detection light from the one side onto the recording surface of a loaded disc;two light receiving regions to receive light reflected from the recording surface, the light source containing a plurality of light emitters, each emitter emitting light of a different wavelength;reflecting material disposed on a side of the recording surface opposite from the one side of the recording surface where the light source is disposed, the reflecting material disposed such that light from the light source is reflected to the receiving regions in the absence of the loaded disc;a band pass filter having a plurality of sections, each section passing light of a wavelength of one of the emitters, the band pass filter disposed such that each light receiving region is divided into a plurality of light receiving sections;a plurality of determining mechanisms to determine a plurality of differences, each determining mechanism to determine a difference between an amount of reflected light received by one light receiving section in one of the light receiving regions and a corresponding light receiving section in another of the light receiving regions, the reflected light being reflected from one of the recording surface and the reflecting material, the plurality of differences being a combination of each difference;a plurality of addition mechanisms to determine a plurality of totals, each addition mechanism to determine a total amount of light received by the one light receiving section in one of the light receiving regions and the corresponding light receiving section in another of the light receiving regions, the reflected light being reflected from one of the recording surface and the reflecting material, the plurality of totals being a combination of each total;a discrimination mechanism to detect the plurality of differences and plurality of totals, the amount of reflected light from the recording surface received by each receiving region dependent on the disc thickness of the loaded disc, the discrimination mechanism to classify the loaded disc dependent on the plurality of differences and the plurality of totals of light reflected from the recording surface, and the discrimination mechanism to detect the absence of the loaded disc in response to the plurality of differences and plurality of totals of light reflected from the reflecting material in the absence of the loaded disc.