Multi-Standard Optical Disk Reading Apparatus and Method of Reading Using Same

1. Field of the Invention

This invention relates to an optical data storage system. More specifically, this invention relates to an optical reading apparatus and related method for an optical data reproduction system which is able to reproduce encoded data at different pit density on varied types of optical disk formats.

2. Description of the Prior Art

Initialized by the vast increase in informatsion that needs to be processed, optical data storage system; have become very important, particularly because of their high storage density per unit area. Most of the recent optical informatsion storage systems use a rotating single optical disk on which the informatsion is digitally stored in concentric circular tracks in an ordered, predefined manner to allow chronological fast reading and fast random access to desired pits of data.

At present, varied types of optical disk systems are provided, for example, the compact disk (CD) system, the Mini-Disk (MD) system and the multi-layered optical disk for digital video disk (DVD) system. Each of these system types use a optical disk format that is fabricated dependent upon a different standard. And thickness or pit density of the optical disks are different from one another. An optical reading system is needed which is able to reproduce the encoded data from any types of optical disk format.

The present invention has for its object to provide a multi-standard optical disk reading system having a capability to sense and determine the type of the optical disk format. This invention can provide an optical disk reading system which is able to read encoded pits on varied types of optical disk format.

The object of the present invention can be achieved by an optical disk reading apparatus and method, the apparatus comprising: a sensing device to detect total number of layers, thickness or diameter of an optical disk, a servo control circuit which controls each servo mechanism such as a focusing servo and a tracking servo, a data processor to process signals detected by a detector in an optical head, and a central processing unit (CPU) which operates the servo control circuit and the data processor for the data reproduction. The total number of data layers, the thickness, or the diameter of the optical disk is detected by the sensing device. Then the standard of the loaded optical disk is determined by processing a detected signal from the sensing device. The CPU references the detected signal to stored data about the standard of varied optical disk format, and then the standard of the loaded optical disk is distinguished by the CPU. In order to reproduce encoded data on the loaded optical disk, the CPU modulates the servo control circuit to set up the movement of the servo mechanisms according to the standard of the optical disk. Also the CPU operates the data processor to select an appropriate data encoding circuit in the data processor according to the standard of the optical disk. After the initial set-up of the servo mechanisms and the data processor is determined, the data reproduction is started.

For a fuller understanding of the nature and advantages of the present invention reference should be made to the following detailed description taken in conjunction with the accompanying drawings.

FIG. 1 is a block diagram of a first example of an optical reading apparatus to which the present invention can be applied;

FIG. 2(a) is a block diagram of a second example of an optical reading apparatus to which the present invention can be applied;

FIG. 2(b) shows a structure of an optical disk which is used in the optical reading apparatus of the present invention described in FIG. 2(a); and

FIG. 2(c) is a structure of an optical disk reading system which is applicable to the optical reading apparatus of the present invention illustrated in FIG. 2(a).

Embodiments of the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of a first example of an optical reading apparatus to which the optical disk reading methods of the present invention can be applied. An optical disk 10 represents one of the optical disk formats among a compact disk (CD), a Mini-Disk (MD), a digital video disk (DVD) or any other. The optical disk 10 is mounted on and secured by a turntable 12 to be rotated by a spindle motor 14. And the total number of data layers or thickness of the optical disk 10 is detected by a photo-interrupter 16 to distinguish the standard and type of the optical disk 10. Encoded pits on the optical disk 10 are read by a pickup 18 which includes a laser diode, a focusing lens, a focusing lens actuator, a tracking actuator and a photo-detector. The output signal from the pickup 18 is transmitted to a focusing servo circuit 20, a tracking servo circuit 22 and a pre-amplifier 24. According to a focusing error signal, the focusing servo circuit 20 modulates the focusing lens actuator to move the focusing lens. And according to a tracking error signal, the tracking servo circuit 22 modulates the tracking actuator to move the pickup 18. The spindle servo circuit 26 modulates the spindle motor 14 in order to track the linear velocity of the optical disk 10.

The output signal applied to the pre-amplifier 24 from the pickup 18, is transmitted to a data processor 28. Then the decoded signal is processed by a central processing unit 30 (CPU). The CPU 30 also processes a detected signal from the photo-interrupter 16 to identify the standard or type of the optical disk 10. The CPU 30 references the detected signal to stored data about the standard of varied optical disk format, in order to distinguish the standard of the optical disk 10. After the standard of the optical disk 10 is identified, a servo control circuit 32 determines the position of, or selects of the focusing lens, by modulating the focusing servo circuit 20, and the tracking servo circuit 22 is modulated to move the pickup 18 in order to trace the pit lane which is fabricated in accordance with the pit density standard.

According to the identified standard of the optical disk 10, the CPU 30 operates the data processor 28 to select an appropriate data encoding circuit in the data processor 28. Then the output signal amplified by the pre-amplifier 24 is decoded by the data processor 28. And the decoded signal is transmitted to an audio processor 34, a sub-picture processor 36 and a video processor 38. The audio processor 34, the sub-picture processor 36 and the video processor 38 are controlled by the CPU 30. The CPU 30 is operated by an operation signal from a key operating unit 40 which transmits all operating signals of an operator. The CPU 30 also controls a display unit 42 to show the status of data reproduction to the operator.

FIG. 2(a) is a block diagram of a second example of an optical reading apparatus to which the optical disk reading methods of the present invention can be applied. A sensing device is used differently from the apparatus described in FIG. 1. An optical disk 50 represents one of the optical disk formats among, a compact disk (CD), a Mini-Disk (MD), a digital video disk (DVD) or the other. And optical disk 50 has an identification mark at its label region, as illustrated in FIG. 2(b). The identification mark is referential to the standard of the optical disk 50. The optical disk 50 is mounted on and secured by a turntable 52 to be rotated by a spindle motor 54. The identification mark of the optical disk 50 is detected by a photo-sensor 56 to distinguish the standard and type of the optical disk 50. Encoded pits on the optical disk 50 are read by a pickup 58 which includes a laser diode, a focusing lens, a focusing lens actuator, a tracking actuator and a photo-detector. The output signal from the pickup 58 is transmitted to a focusing servo circuit 60, a tracking servo circuit 62 and a pre-amplifier 64. According to a focusing error signal, the focusing servo circuit 60 modulates the focusing lens actuator to move the focusing lens. And according to a tracking error signal, the tracking servo circuit 62 modulates the tracking actuator to move the pickup 58. The spindle servo circuit 66 modulates the spindle motor 54 in order to track the linear velocity of the optical disk 50.

The output signal applied to the pre-amplifier 64 from the pickup 58, is transmitted to a data processor 68. Then the decoded signal is processed by a central processing unit 70 (CPU). The CPU 70 also processes a detected signal from the photo-sensor 56 to identify the standard or type of the optical disk 50. The CPU 70 references the detected signal to stored data about the standard of varied optical disk format, in order to distinguish the standard of the optical disk 50. After the standard of the optical disk 50 is identified, a servo control circuit 72 determines the position of, or selects the focusing len, by modulating the focusing servo circuit 60, and the tracking servo circuit 62 is modulated to move the pickup 58 in order to trace the pit lane which is fabricated in accordance with the pit density standard (which is among the details of how data is stored on the disk).

According to the identified standard of the optical disk 50, the CPU 70 operates the data processor 68 to select an appropriate data encoding circuit in the data processor 68. Then the output signal amplified by the pre-amplifier 64 is decoded by the data processor 68. And the decoded signal is transmitted to an audio processor 74, a sub-picture processor 76 and a video processor 78. The audio processor 74, the sub-picture processor 76 and the video processor 78 are controlled by the CPU 70. The CPU 70 is operated by an operation signal from a key operating unit 80 which transmits all operating signals of an operator. The CPU 70 also controls a display unit 82 to show the data reproduction status to the operator.

FIG. 2(b) is a a structure of an optical disk which is applicable to the optical reading apparatus of the present invention described above with respect to FIG. 2(a). An optical disk has a center hole 2, label region 4 and encoded data region 6. An identification mark 8 is placed in the label region 4 to be detected by the photo-sensor 56 in FIG. 2(a). And the identification mark is referential to the standard of the optical disk. It represents data as to the total number of data encoded layers and the data reproduction in order to set up the movement of the servo mechanisms.

FIG. 2(c) is a a structure of an optical disk reading system which is applicable to the optical reading apparatus of the present invention illustrated in FIG. 2(a). An optical disk 11 has a label region 11a and a data encoded region 11b. An optical disk 11 is one of the optical disk formats among a compact disk (CD), a Mini-Disk (MD), a digital video disk (DVD) or any other. And the type or standard of the optical disk 11 is distinguished by an identification groove 13. The optical disk 11 is secured by a center pivot 15, and mounted on a turntable 17 to be rotated by a spindle shaft 19 which is driven by a spindle motor 21. A touch-sensing device 23 is mounted on the turntable 17. And the identification groove 13 is detected by a touch-pin 25 of the touch-sensing device 23. After the standard of the optical disk 11 is identified to set up the movement of servo mechanisms or a data processor, the data reproduction is started.

Although the invention has been particularly shown and described, it is contemplated that various changes and modification may be made without departing from the scope of the invention as set forth in the following claims.