Dynamic information storage or retrieval – Dynamic mechanism subsystem – Access of multiple storage elements
Reexamination Certificate
1998-06-30
2001-05-29
Tran, Thang V. (Department: 2651)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Access of multiple storage elements
C369S044190, C369S044170
Reexamination Certificate
active
06240059
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of optical storage drives, and particularly to an optical pickup mechanism for optical storage drives using dual-sided optical storage discs.
BACKGROUND OF THE INVENTION
Optical storage drives such as CD-ROM and DVD drives are well known in the art. An important element in such drives is the optical pickup unit (OPU). Typically, the OPU comprises laser light emitting diode, light detector, optical lens, and a voice coil. The voice coil is used to position the lens for proper focusing and tracking during a read/write operation. To be able to access different data tracks in an optical storage device, e.g., CD-ROM, the entire OPU has to move radially to the storage device on a linear sliding rail system. The OPU and the mechanism for positioning the OPU shall collectively be referred to as an optical pickup mechanism.
Some optical storage discs, e.g. laser discs and DVDs, have data stored on both sides. Therefore, some optical storage drives are equipped to access data from both sides of the disc. Currently, there are basically three different designs for accessing data from dual-sided discs. One way is to use a U-shape sliding rail system where a single OPU can move to either side of the disc. The second method is to employ two OPUs, one for each side of the disc. The third way is to manually flip the disc so the side to be accessed is facing the OPU.
All of these designs suffer from a number of shortcomings. First and foremost, all of the designs described above use a configuration where the entire OPU moves on a linear sliding rail system. Although this current configuration where the entire OPU moves on a linear sliding rail system has been used successfully for many years, it has its limitations, particularly in light of the current shorter data access time requirement. The OPU is a relatively bulky device which slows down the movement of the entire mechanism, and consequently, the time it takes to move from one track to a different track is increased. Although attempts have been made to increase the mobility of the OPU by applying more powerful motors, this has led to increased vibration, particularly in the voice coil which is most susceptible. Hence, the time saved from increased acceleration is offset by the time it takes to stabilize the unit before the accessed data can be read or written.
In addition, there are problems which are specific to each of the designs mentioned above. For the first design using a U-shaped rail, the system suffers from complexity and bulkiness, and hence takes up excessive amount of space and material. For the second design which uses the two OPUs, the main problem is cost, as OPU is an expensive component in an optical storage drive. For the third design, the main shortcoming is the inconvenience to the user who has to manually flip the disc.
To have a reliable and superior optical pickup mechanism which can read/write both sides of an optical storage disc, it must be capable of high acceleration without incurring vibrational problems. Moreover, it should be simple in design, convenient to the user, and inexpensive to manufacture. Since such a mechanism would greatly shorten the data access time of the current optical storage drives, save time and cost in manufacturing, and be attractive to the end users, it is easy to why such an optical pickup mechanism would be highly desirable and useful.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide optical pickup mechanism which can access data tracks on both sides of a dual-sided optical storage disc.
It is another object of the invention to provide an optical pickup mechanism which would mechanically facilitate a fast data track access in a optical storage drive.
It is another object of the present invention to provide a multi-head optical pickup mechanism which would minimize induced vibration during high acceleration.
It is yet another object of the present invention to provide a multi-head optical pickup mechanism which is simple in design, relatively inexpensive to manufacture, and is convenient.
SUMMARY OF THE INVENTION
The present invention basically comprises an optical pickup unit (OPU) connected to an optical pipe. A baffle is provided which surrounds the OPU and a cover is provided which is placed on top of the baffle. To be able to controllably rotate the optical pipe, a first gear is attached to the pipe. The first gear is meshed with a second gear which is connected to a motor. The pipe should preferably be made of light and durable material to reduce its overall moment of inertia.
The optical pipe comprises a top hollow tube having a top channel and a bottom tube having a bottom channel, and a main body having a main channel. The top and bottom channels terminate to a lens element. The top tube is bent at an angle in two places (here at 90 degrees) though it can be bent at fewer or more places or at a different angle depending on how one wants to direct the light beam. At each of the bent corners, a reflective mirror is placed to direct the light to the respective lens element. For the bottom tube, a reflective mirror is placed at the bend near the lens element, and another mirror is placed at the bottom/main channel junction to direct the light to the lens element.
The mirror at the junction is a special semi-transparent mirror which allows some light to go through while reflecting the rest. Hence, the light which enters the opening of the main channel is both reflected into the top channel and the bottom channel. Similarly, a light beam which is reflected back through the bottom lens element is reflected off the mirrors and is directed towards the opening. A light ray which enters through the top lens element is reflected off the reflective mirrors, but is allowed to go through the semi-transparent mirror at the junction to eventually reach the opening at the main channel.
The OPU is a standard item currently available. The eye of the OPU for emanating and receiving light beams is placed directly under the opening such that any light emanating from the OPU is directed to the lens element, and any light reflected back into the lens element is directed back to the OPU eye.
The optical pipe can rotate freely via the gears and the motor. The present optical pickup mechanism should be positioned in an optical storage drive such that an optical storage disc can be placed in between the two lens elements of the optical pipe. To be able to access all the tracks on an optical storage disc from either side, the pipe should be situated adjacent to the storage device such that the two lens elements of the pipe cut across every track of the optical storage disc when the pipe is rotated. By combining the spinning action of the storage disc and the rotational movement of the optical pipe, any segment of data from the storage device can be uniquely accessed.
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Nguyen Michael Anh
Zheng Tang
Chu Kim-Kwok
Ho Lawrence Y. D.
Nguyen Michael Anh
Tran Thang V.
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