Multi-standard optical disk reading apparatus and method of reading using same

An optical disk reading apparatus and method to provide an optical disk reading system which is able to reproduce encoded optical data from varied optical disk formats fabricated in accordance with different standards. After loading an optical disk, a sensing device detects the total number of data layers, diameter or thickness, to identify the standard of the optical disk. The standard or type of an optical disk can be identified by detecting an identification mark, if the optical disk has one. A central processing unit (CPU) distinguishes the standard by referring the detected signal to stored data about the standard of various optical disk formats. 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 identified 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.

BACKGROUND OF THE INVENTION 
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. 
SUMMARY OF THE INVENTION 
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.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
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.