1. Field of the Invention
The present invention relates to an apparatus for generating tracking error signals, and more particularly to an apparatus for generating tracking error signals from a reflected and received light from a recording surface of optical disks.
The present application is based on Korean Patent Application No. 2002-45139, filed Jul. 31, 2002, which is incorporated herein by reference in its entirety
2. Background of the Related Art
Optical disks, for example, a compact disk(CD) and a digital video disk(DVD), include tracks of spiral shape. Disk players which read out information recorded on these disks emit a light on the optical disks. In order for an optical pickup apparatus, which receives a light reflected from the recording surface, to extract data with no errors, it is necessary to follow tracks with precision. To do this, tracking error signals are generated by using information of optical distribution incident upon a quarterly-divided optical detector which usually receives a light reflected by the recording surface of an optical disk.
For example, optical disk players for DVD generate tracking error signals by using a phase-difference detection method. Korean Patent Laid-Open Publication No. 1998-082277 discloses an apparatus for generating tracking error signals by means of a phase-difference detection method. This apparatus, however, has some problems in that it cannot correct errors of some distortions of the optical detector when a light is received by the optical detector after being reflected from the optical disks. Particularly, when the pit/land length is short, the amplitude of the pick-up signals is very much decreased due to the modulation transfer function(MTF) of the optical pickup, so the effect of noise becomes great. With the MTF, if either the pit/land length gets shorter or the reading speed gets larger, the frequency of the output signals will increase, and as a result, the amplitude of the pick-up signals will decrease. Accordingly, to increase the recording density and speed, it is required to find a method for correcting these signal distortions.
On the other hand, U.S. Pat. No. 6,317,396 B1 discloses an apparatus for generating tracking error signals to reduce problems from these signal distortions. However, an apparatus as suggested in U.S. Pat. No. 6,317,396 B1 uses signals directly from the optical detector and distinguishes errors. Further, its circuit embodiment gets very complicated.