Seek operation on different recording density regions based on the reflection of a boundary area

A seek control method for an optical disk comprising the steps of:

• providing an information recording area of the optical disk radially divided into a plurality of recording areas, with a boundary area, having a width and no data recorded therein, interposed therebetween, the boundary area being either a high-reflection area that presents a higher reflection light level than that of the recording areas or a low-reflection area that presents a lower reflection light level than that of the recording areas;
• calculating a distance, from a start point, of one of the recording areas that contains a designated target point, to the designated target point, when an instruction is given to move an optical head from a current point to the target point over the optical disk;
• performing a seek operation, up to the start point of the recording area containing the target point, by detecting, based on either a higher reflection level or a lower reflection level than that of the recording areas, the boundary area located between the one of the recording areas containing the current point and the recording area containing the target point;
• and
• further performing a seek operation up to the target point based on the distance calculated by said step of calculating,
• wherein information is recorded in the recording areas of the optical disk with recording density differing between the recorded areas, and the distance, from the start point of the recording area containing the target point, to the target point is calculated based on a variation in the recording density.

A seek control device for an optical disk, an information recording area of the optical disk being divided radially into a plurality of recording areas, with a boundary area, having a width and no data recorded therein, interposed therebetween, the boundary area being either a high-reflection area that presents a higher reflection light level than that of the recording areas or a low-reflection area that presents a lower reflection light level than that of the recording areas, said seek control device comprising:

• an optical head that irradiates a light beam onto the optical disk and detects reflection light from the optical disk;
• a distance calculating section that calculates a distance, from a start point, of one of the recording areas that contains a designated target point, to the designated target point, when an optical head is to be moved from a current point to the target point over the optical disk;
• a boundary signal detector section that detects a boundary signal indicative of the boundary area based on a varying output level of said optical head as said optical head is moved from the current point to the target point;
• and
• a servo control section that detects the start point, of the recording area containing the target point, based on detection by said boundary signal detector section and drives said optical head up to the target point based on the distance calculated by said distance calculating section,
• wherein information is recorded in the recording areas of the optical disk with recording density differing between the recorded areas, and said servo control section calculates the distance, from the start point of the recording area containing the target point, to the target point based on a variation in the recording density.

A seek control device for an optical disk, an information recording area of the optical disk being divided radially into a plurality of recording areas, with a boundary area, having a width and no data recorded therein, interposed therebetween, the boundary area being either a high-reflection area that presents a higher reflection light level than that of the recording areas or a low-reflection area that presents a lower reflection light level than that of the recording areas, said seek control device comprising:

• an optical head that irradiates a light beam onto the optical disk and detects reflection light from the optical disk;
• a distance calculating section that calculates a distance, from a start point, of one of the recording areas that contains a designated target point, to the designated target point, when an optical head is to be moved from a current point to the target point over the optical disk;
• a boundary signal detector section that detects a boundary signal indicative of the boundary area based on a varying output level of said optical head as said optical head is moved from the current point to the target point;
• and
• a servo control section that detects the start point of the recording area containing the target point based on detection by said boundary signal detector section and drives said optical head up to the target point based on the distance calculated by said distance calculating section.