The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 04, 2000
Filed:
Jun. 11, 1998
Hideyo Kamiyama, Tokorozawa, JP;
Pioneer Electronic Corporation, Tokyo, JP;
Abstract
A defect detection apparatus has a simple constitution and performs accurate defect detection while clearly differentiating between defect detection and tracking error detection. The defect detection apparatus includes a photodetector having a light-receiving area for receiving a return light beam from a recording medium irradiated with a light beam. A defect on the recording medium is detected based on an output from the photodetector. The defect detection apparatus according to the present invention comprises signal generation means for generating on the basis of an output from the photodetector at least two phase detection signals having phases which vary in a manner complementary to each other according to a deviation of the light beam from a track of the recording medium, adding means for adding up absolute value of the phase detection signal to generate a sum total signal having a value corresponding to a result of the addition, and discrimination means for comparing the value of the sum total signal with a predetermined reference value so as to generate a defect detection signal based on a result of the comparison.