Optical: systems and elements – Lens – With support
Reexamination Certificate
2000-01-26
2001-10-16
Ben, Loha (Department: 2873)
Optical: systems and elements
Lens
With support
C359S814000, C369S044140, C369S044150
Reexamination Certificate
active
06304391
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an object lens supporting unit for supporting an object lens used in an optical pick-up of an optical disk drive, in particular, to the unit supporting so as to permit the object lens to move by suspension wires and a method of assembling the unit.
Generally, as a recording apparatus connected to an electrical apparatus such as a personal computer, a recording apparatus using a semiconductor memory chip or using magnetically and/or optically recording medium is well known. An optical disk drive as a kind of the lafter can read data from an optical recording medium of disk type by irradiating laser beam to the medium and optically sensing reflected laser beam from the medium. The object lens supporting unit according to this invention is applied to the optical disk drive. The optical disk drive can further write data to the optical recording medium of disk type by irradiating laser beam to the medium. The object lens supporting unit according to this invention is applied to the optical disk drive.
The optical recording media of disk type are roughly classified into media capable of reading only or media capable of reading and writing. As the media capable of reading only, an Audio CD (an Audio Compact Disc), a CD-ROM (a Compact Disc-Read Only Memory), a DVD-Audio (a Digital Versatile Disc-Audio), a DVD-Video (a Digital Versatile Disc-Video), a DVD-ROM (a Digital Versatile Disc-Read Only Memory), and an SACD (a Super Audio Compact Disc) have been known. As the media capable of reading and writing, a CD-R (a Compact Disc-Recordable), a CD-RW (a Compact Disc-ReWritable), a DVD-RAM (a Digital Versatile Disc-Random Access Memory), and a DVD-RW (a Digital Versatile Disc-ReWritable) have been known.
In order to write data to the CD-R, it is necessary to use an optical disk drive for the exclusive use and a writing application software for the exclusive use. In the CD-R, it is impossible to delete data written once thereon while it is possible to additionally and repeatedly write new data thereon.
A conventional object lens supporting unit applied in a CD-R drive as an optical disk drive will be described.
The CD-R drive has an optical pick-up. The optical pick-up is driven in a direction that traverses innumerable tracks formed on a CD-R and is stopped on a target track so as to irradiate a laser beam to the target track and to optically sense a reflected laser beam from the target track/irradiate a laser beam to the target track. The optical pick-up has a laser source for generating the laser beam, an optical system for transmitting the laser beam irradiated from the laser source to the CD-R and reflected by the CD-R, and a light sensor for sensing the reflected laser beam. The optical pick-up is movable in a tracking direction (a diameter direction of the CD-R). Furthermore, an object lens included in the optical system is supported by an object lens supporting unit so that it is slightly movable in the tracking direction and a focusing direction (a thickness direction of the CD-R).
The optical pick-up of the CD-R drive is designed so as to deal with both of reading data from the CD-R and writing data to the CD-R because the CD-R is capable of reading and writing data. Herein, a power of the laser beam of the optical pick-up must be changed at which data are read and data are written. This is because it is necessary for writing data a power higher than a power for reading data in order to form pits on the CD-R by irradiating the laser beam. For example, the power for writing is approximately 10 to 20 times as high as the power for reading.
The laser beam generated from the laser source is transmitted through the optical system (a diffraction grating, a beam splitter, a collimator, and the object lens) and irradiated on the CD-R. On the other hand, the laser beam reflected from the CD-R is transmitted through the optical system (the object lens, the collimator, and the beam splitter) and sensed by the light sensor. During the laser beam is transmitted through the optical system, the object lens movably supported by suspension wires are driven by a driving mechanism so as to be adjusted on an appropriate position in the focusing and the tracking directions. The driving mechanism has focusing and tracking coil. The focusing and the tracking coils are provided by the object lens supporting unit.
Often, the suspension wire has been already warped in a stage when the suspension wire is prepared in order to assembling the object lens supporting unit. This is because the suspension wire is like as a piano wire. If the object lens is supported by the warped suspension wire, an optical axis of the object lens is deviated in the tracking direction from a standard or a datum position. Furthermore, even if the object lens is supported by the warped suspension wire with the optical axis in the standard position, the suspension wire and the other parts of the object lens supporting unit adjacent to the wire are stressed. The object lens supporting unit in which the parts are stressed degrades in movement. Although it may deal with the matter mentioned above to assemble the object lens supporting unit with sorting out the warped suspension wire and only using the suspension wire not warped, it reduces manufacturing efficiency and increases manufacturing cost.
SUMMARY OF THE INVENTION
It is an object of this invention to deal with disadvantages mentioned above and to therefore provide an object lens supporting unit capable of dealing with the matter caused by warp of the suspension wire without spoiling manufacturing efficiency and cost.
It is another object of this invention to provide a method of assembling an object lens supporting unit capable of dealing with the matter caused by warp of the suspension wire without spoiling manufacturing efficiency and cost.
The other object, features, and advantages of this invention will become clear as the description proceeds.
This invention is directed to an object lens supporting unit used for supporting an object lens, the object lens converging a laser beam irradiated from a laser source on an optical disk, so that the object lens is movable in tracking and focusing directions parallel to diameter and thickness directions of the optical disk. The unit comprises a supporting frame and a lens holder, the supporting frame having a hole portion for containing and gluing a suspension wire therein, the lens holder mounting the object lens thereon, which being supported by the supporting frame through the suspension wire, and which being movable in the tracking and the focusing directions. The hole portion is formed so as to permit a positional deviation of the suspension wire deviated from a normal position in at least one of the tracking and the focusing directions.
This invention is further directed to a method of assembling an object lens supporting unit used for supporting an object lens, the object lens converging a laser beam irradiated from a laser source on an optical disk, so that the object lens is movable in tracking and focusing directions parallel to diameter and thickness directions of the optical disk. The unit comprises a supporting frame and a lens holder, the supporting frame having a hole portion for containing and gluing a suspension wire therein, the lens holder mounting the object lens thereon, which being supported by the supporting frame through the suspension wire, and which being movable in the tracking and the focusing directions. The method comprising the steps of previously forming the hole portion on the supporting frame so that the hole portion permits a positional deviation of the suspension wire deviated from a normal position in at least one of the tracking and the focusing directions, attaching the object lens to the lens holder, gluing one end of the suspension wire on the lens holder, inserting the other end of the suspension wire glued on the lens holder into the hole portion, adjusting a position of the lens holder so that the object lens is placed in a normal positio
Ben Loha
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Mitsumi Electric Co. Ltd.
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