This application claims the benefit of Korean Patent Application No. 2001-1129 filed on Jan. 9, 2001, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a tilt compensation method and an apparatus therefor, and more particularly, to a method of compensating for the tilt of an optical recording medium in which the tilt margin is between 0 and 0.0052, that is, 0 less than tilt margin less than 0.0052, and an apparatus used therefor.
2. Description of the Related Art
When an optical disc such as a DVD or a CD-RW used for high density recording is tilted, an error is generated during recording or reproducing data according to a degree of tilt. When the disc is tilted severely, recording or reproducing of data itself is difficult.
Table 1 below shows how margin changes, with respect to the characteristic of light and the change in tilt and thickness of an optical disc at a data recording surface thereof, according to a change in numerical aperture (NA), may affect a process of recording data on the optical disc. As shown in the table, when the numeral aperture increases, a spot size decreases so that the data recording capacity is increased. However, it is also shown that the depth of focus and margin of disc tilt are reduced.
A new optical disc named as a DDCD (double density CD) has been suggested. The DDCD uses the same wavelength as the wavelength used for an existing CD while using an objective lens having a larger NA and having a small track pitch. Also, the NA of a DDCD is different from that of an existing DVD (digital versatile disc).
Thus, a tilt margin of the DDCD is clearly different from that of the existing CD or DVD. Table 2 shows the characteristics of a CD, a DDCD and a DVD. In Table 2, the NA of the DDCD is 0.50 for reading only, that is, for reproducing only and 0.55 when used for both reading and recording. The NA of the CD is 0.45 for reading only and 0.50 when used for both reading and recording. The NA of the DVD is 0.60 when used for both reading only and reading and recording together. It can be seen that the NA of the DDCD is greater than that of the existing CD and less than the existing DVD.
Table 3 below shows the result of calculation of tilt margin with respect to a CD, DDCD and DVD by using a mathematical formula (xcex/tNA3; where xe2x80x9ctxe2x80x9d denotes the thickness of a disc) indicating a tilt margin.
It can be seen from Table 3 that the tilt margin of a DDCD is less than that of a CD and 22% less than that of a DVD. Such a fact can also be seen from FIG. 1.
In detail, FIG. 1 is a graph showing the cases of different NAs which may have the same tilt margin as that of a DVD. In the graph, the horizontal axis denotes wavelength (nm) and the vertical axis denotes the thickness of an optical disc (mm). The first and second lines G1 and G2 indicate a change of the tilt margin of a CD-R/RW when the NA is 0.5 and a change of the tilt margin of a DVD when the NA is 0.6, respectively. In FIG. 1, all lines indicating different NAs show the same tilt margins. For example, the tilt margins indicated by the first and second lines G1 and G2 are the same.
The NA of a DDCD is 0.55 for recording and reproducing, and a graph corresponding to this condition is indicated by a projection line which is positioned between the first and second lines G1 and G2. Thus, if the tilt margin of a DDCD having a NA of 0.55 is the same as that of a DVD, since the wavelength of a DDCD is 780 nm, the thickness of the DDCD must be about 0.92 mm. However, since the thickness of a DDCD is actually 1.2 mm, the tilt margin of the DDCD naturally decreases, which can be seen from the above mathematical formula. Therefore, since the tilt margin of DDCD is different from that of CD or DVD, correction for this difference is needed.
Accordingly, it is an object of the present invention to provide a tilt compensation method by which recording is performed by controlling power and/or time needed for recording according to the tilt of an optical recording medium.
It is another object of the present invention to provide a method that adaptively compensates for a recording pulse according to the detected tilt of an optical recording medium.
It is yet another object of the present invention to provide a tilt compensating apparatus which performs recording by controlling power and/or time needed to record according to the tilt of an optical recording medium.
It is yet another object of the present invention to provide a tilt compensating apparatus to adaptively compensate for a recording pulse according to the detected tilt of an optical recording medium.
The foregoing and other objects of the present invention are achieved by providing a method that compensates for a tilt of a recordable and reproducible optical recording medium comprising detecting a tilt of the optical recording medium, and compensating for a recording signal having a predetermined recording pattern by using a predetermined system according to the detected tilt, wherein, when detecting the tilt, the tilt is detected with respect to an optical recording medium in which a tilt margin is greater than 0 and less than 0.0052 (0 less than tilt margin less than 0.0052).
The foregoing and other objects are also achieved by providing a method that compensates for a tilt of an optical recording medium when input data is recorded as a mark and a space by a recording pulse having a predetermined recording pattern. The method comprises detecting a tilt of the optical recording medium, and adaptively compensating for the recording pattern according to the detected tilt by using a memory, where a recording power and/or time compensating for the amount of shift of the recording pattern and the length and width of a mark according to the tilt and/or the length of the mark is stored, wherein, during detecting the tilt, the tilt is detected with respect to an optical recording medium in which a tilt margin is greater than 0 and less than 0.0052 (0 less than tilt margin less than 0.0052).
The foregoing and other objects may also be achieved by providing an apparatus that compensates for a tilt of a recordable and reproducible optical recording medium comprising a tilt detector detecting a tilt of the optical recording medium, and a recording compensator compensating for a recording signal having a predetermined recording pattern by using a predetermined system according to the tilt detected by the tilt detector, wherein the tilt detector detects the tilt with respect to an optical recording medium in which a tilt margin is greater than 0 and less than 0.0052 (0 less than tilt margin less than 0.0052) and the recording compensator compensates for the detected tilt.
The foregoing and other objects may also be achieved by providing an apparatus that compensates for a tilt of an optical recording medium when input data is recorded as a mark and a space by a recording pulse having a predetermined recording pattern, the apparatus comprising a tilt detector detecting a tilt of the optical recording medium, and a recording compensator adaptively compensating for the recording pattern according to the tilt detected by the tilt detector by using a memory where a recording power and/or time compensating for the amount of shift of the recording pattern and the length and width of a mark according to the tilt and/or the length of the mark is stored, wherein the tilt detector detects the tilt with respect to an optical recording medium in which a tilt margin is greater than 0 and less than 0.0052 (0 less than tilt margin less than 0.0052) and the recording compensator compensates for the detected tilt.