The present invention relates to a method of controlling data writing velocity of an optical disk player and an optical disk player employing said method.
Optical disk players have been used so as to write data on optical disks, e.g., CD-R (Compact Disk-Recordable), CD-RW (Compact Disk-ReWritable).
Rotational speed of an optical disk while writing data is controlled on the basis of writing velocity, e.g., linear velocity, angular velocity.
In a conventional optical disk player, for example, the revolution number of an optical disk is controlled to maintain linear velocity for writing data on an optical disk. By maintaining the linear velocity, the data can be written with fixed pit density. This writing manner is called a CLV (Constant Linear Velocity) manner. In the CLV manner, the linear velocity is maintained, so the revolution number of the optical disk is gradually reduced while data are written toward an outer part of the disk.
To accelerate the data writing velocity by the CLV manner, the revolution number of the optical disk is merely increased, so that the revolution number is too great to write data in the inner part of the optical disk. Further, a spindle motor, which rotates the optical disk, is over-loaded. Thus, data cannot be securely written in the inner part of the optical disk, and reliability of data must be lower.
This problem of the CLV manner was solved by a zone CLV manner, in which data can be written in the inner part of the optical disk without extremely increasing the revolution number of the optical disk and total writing time can be shortened.
In the zone CLV manner, a data writing area of the optical disk is divided into a plurality of zones, and the CLV manner is applied to each zone. Firstly, the linear velocity for writing data in the innermost zone of the disk without applying overload to the spindle motor is determined. Then, the linear velocity for other zones are determined. The linear velocity for writing data is accelerated, by stages, toward the outermost zone of the optical disk. The linear velocity of the zones can be determined on the basis of rotational speed of the spindle motor for writing data in the innermost zone as a standard speed, so reliability of data written in the innermost zone can be improved.
A conventional method of controlling data writing velocity by the zone CLV manner will be explained with reference to FIGS. 6 and 7.
In a graph of FIG. 6, the horizontal axis is address or time of writing data; the vertical axis is the revolution number of the spindle motor.
A controller of the optical disk player reads address data from a wobble groove, which has been previously grooved in the optical disk 10. The optical disk player employing the zone CLV manner uses an innermost area of the optical disk 10 as an optimum power control (OPC) area 14, in which data writing test is executed. By the data writing test in the OPC area 14, optimum laser power for writing data on the optical disk 10 is determined.
Since the OPC area 14 is the innermost area of the optical disk 10, a revolution number of the spindle motor for the data writing test in the OPC area 14 may be regarded as a revolution number for correctly writing data. Therefore, we call that revolution number the safety revolution number.
The controller of the optical disk player controls data writing velocity in zones 11, 12 and 13 of the optical disk 10 respectively. The data writing area has been previously divided into the zones by a firmware. The data writing velocity is accelerated, by stages, toward the outermost zone 13 of the optical disk 10.
An example of a control flow chart of the zone CLV manner is shown in FIG. 8. In the conventional zone CLV manner, firstly the data writing test is executed in the innermost OPC area 14 with 16× writing velocity. Then, an analyzer determines optimum laser power for writing data on the optical disk 10.
After the optimum laser power is determined, the controller writes data in the zone 11 of the data writing area of the optical disk 10 with 16× velocity (Step S801). Then, data are written in the zone 12 with 20× velocity (Step S802) and in the zone 13 with 24× velocity (Step S803). Namely, the data writing velocity is accelerated, by stages, toward an outer edge of the optical disk 10.
By employing the zone CLV manner, the revolution number of the spindle motor for writing data in the innermost zone 11 without applying overload can be determined. Therefore, reliability of data written in the innermost zone 11 can be improved, and total time for writing data can be shortened.
These days, industrial standards of optical disks have been settled. Therefore, standard disks are mainly supplied. However, nonstandard disks, which have greater recording density and capacity, are also required.
Velocity changing points of the standard disk, at which the data writing velocity is changed, have been previously written in the firmware of the optical disk player. For example, in the case of a nonstandard optical disk having narrow track pitch or greater recording capacity, optimum velocity changing points are shifted inward with respect to those of the standard disk. If the data writing velocity is accelerated at the velocity changing points of the standard disk, there is a case that the revolution number of the spindle motor is made greater than the safety revolution number, so that reliability of written data is made lower (see FIG. 9). Note that, FIG. 9 is a graph showing a relationship between the revolution number of the spindle motor and address or time of writing data in the nonstandard disk having the narrow pitch.
On the other hand, in the case of a nonstandard optical disk having wide track pitch or smaller recording capacity, optimum velocity changing points are shifted outward with respect to those of the standard disk. Even if the data writing velocity is accelerated at the velocity changing points of the standard disk, the revolution number of the spindle motor is always smaller than the safety revolution number. Namely, the optical disk player cannot give full data writing function, and time for writing data must be longer (see FIG. 10). Note that, FIG. 10 is a graph showing a relationship between the revolution number of the spindle motor and address or time of writing data in the nonstandard disk having the wide pitch.