1. Field of the Invention
The present invention relates to a disk drive apparatus having a compensation means for reading information with high accuracy from an information read/write medium such as a CD and DVD.
2. Description of Related Art
A disk drive apparatus which reads information from an information read/write medium, such as a CD (Compact Disk) and DVD (Digital Video Disk or Digital Versatile Disk), performs error correction processing on a signal read, for example, from a CD by the pickup through CIRC (Cross Interleaved Reed Solomon Code) demodulation.
The error correction through the CIRC demodulation has a considerably superior capability for error correction. However, variations of the CD and DVD families have increased, being followed by an increased demand for a disk drive apparatus having compatibility by which such information read/write media can be commonly used. Accordingly, it is desired that a disk drive apparatus having a high accuracy reading capability be developed.
For example, to read information stored on different types of information read/write media, optically detected are signals affected by differences such as an optical characteristic or linear speed in reading of each information read/write medium. Error correction is then performed through the CIRC demodulation in accordance with the optically detected signals. As the result, technical problems have generally been pointed out that, for example, variations occur in the error correction rate depending on the type of the information read/write media, thereby making it difficult to improve the error correction rate.
The present invention was developed to overcome the prior art problems mentioned above. It is an object of the present invention to provide a disk drive apparatus having compensation means for reading information, with higher accuracy, stored on an information read/write medium.
In order to achieve the aforementioned object, the present invention provides a disk drive apparatus, which reads information stored on an information read/write medium, characterized by comprising the following means.
That is, the disk drive apparatus according to the present invention comprises a pickup for optically reading information written on the aforementioned information read/write medium, and a signal generating means for generating an uncompensated RF signal in accordance with a signal read by the aforementioned pickup. The disk drive apparatus also comprises a compensation means for compensating the frequency characteristic of the aforementioned uncompensated RF signal to output a compensated RF signal, and a control means for adjusting the frequency characteristic of the compensation means with respect to the aforementioned uncompensated RF signal.
With such a configuration, suppose that the RF signal (uncompensated RF signal) generated by the signal generating means in accordance with the signal read by the pickup has changed in response to a difference in the type of information read/write media. In this case, the compensation means can adjust the frequency characteristic of the uncompensated RF signal to thereby generate an RF signal (compensated RF signal) having a waveform which is not affected by the differences in types of information read/write media. Thus, performing EFM or CIRC demodulation or the like in accordance with the compensated RF signal allows a reduction in error rate, thereby making it possible to improve reading accuracy.