Category:History of electrical engineering
Category:History of computing in the United States
Category:History of electronic engineering
Category:History of computing hardware
Category:Synthetic reticular chemistry
Category:Information science
Category:Nuclear history1. Technical Field
This invention relates generally to an optical disk reproducing apparatus and, more particularly, to a method for an optical disk reproducing apparatus capable of correcting a focus error.
2. Related Art
As a method of detecting a focus error signal which has been used in optical disk reproducing apparatuses, there is a technique for detecting the focus error signal by forming pits on the recording surface of an optical disk, for example, and detecting light reflected from the recording surface of the optical disk.
For example, as shown in FIG. 10A, a pit pattern 012 which is provided on the surface of the optical disk 1001 is detected by a photo detector 102.
When a light spot (not shown) is formed on the optical disk 1001 and a light is applied to the optical disk 1001 by the photo detector 102, for example, light reflected from the recording surface of the optical disk 1001 is detected by the photo detector 102 and converted into a pulse signal as shown in FIG. 10B.
Thereafter, as shown in FIG. 10C, the pulses are counted by a pulse counter 103 which has a count of the pulses.
For example, as shown in FIG. 10D, the focus error signal is obtained by detecting the change in the amount of light reflected from the pit pattern 012, by detecting the number of pulses which have increased, with respect to the number of pulses which have decreased, as the light spot scans the pit pattern 012.
In recent years, a high-density recording technique has been developed, so that in an optical disk recording apparatus, a pitch between the pits is reduced. As a result, a light spot which is applied to the optical disk is projected on a portion between the pits.
In the case in which a light spot is projected on a portion between the pits, the center of the light spot is deviated from a pit position (zero-cross point), as shown in FIG. 11A. When the light spot is applied to the pit pattern 012 of the optical disk 1001, as shown in FIG. 11B, a reflected light is incident on the photo detector 102.
The reflected light is detected by the photo detector 102. However, a 01e38acffe
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