Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
2000-05-02
2003-11-25
Psitos, Aristotelis M. (Department: 2653)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
C369S044320
Reexamination Certificate
active
06654326
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application entitled Automatic Tilt Adjustment Device and an Optical Recording/Reproducing Apparatus Having the Same earlier filed in the Korean Industrial Property Office on May 3, 1999, and there duly assigned Serial No. 99-15886 by that Office and an application entitled Automatic Tilt Adjustment Device and an Optical Recording/Reproducing Apparatus Having the Same earlier filed in the Korean Industrial Property Office on May 3, 1999, and there duly assigned Serial No. 99-15887 by that Office.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical recording and reproducing apparatus, and more particularly to an automatic tilt compensator and an optical recording and reproducing apparatus having the same for automatically detecting and compensating for a deformation of a disc which is rotated while the optical recording and reproducing apparatus is operated.
2. Description of the Related Art
An optical recording/reproducing apparatus is a device for recording and/or reproducing desired information on a disc by using an optical device. In such an optical recording/reproducing apparatus, a disc is seated on a turntable by a disc loading apparatus, and rotated at a predetermined speed by a rotating unit, that is, a spindle motor. While the disc is rotated, a pickup unit travels in a radial direction of the disc and radiates a laser beam on the disc, so that the pickup unit reproduces or records information.
At this time, the laser beam radiated from the pickup unit, that is, an optical axis of the laser beam is perpendicular to a surface of the disc, and the pickup unit travels while maintaining a predetermined parallel level with respect to the surface of the disc. If the pickup unit fails to maintain the predetermined level with respect to the surface of the disc, as a result, by certain external factors, that is, a disc tilt or assembly errors of the pickup unit and a feeding part of the pickup unit, a situation occurs in which information can not be reproduced or recorded on a disc. In particular, since a record pit of a Digital Versatile Disc (DVD), which has been in a great demand recently, is smaller than that of a Compact Disc (CD), the Digital Versatile Disc is sensitively responsive to a tilt of a disc.
Accordingly, in a general optical recording/reproducing apparatus, when the pickup unit fails to maintain the predetermined level with respect to a surface of a disc due to the above disc tilt, or assembly errors of the pickup unit and the like, in other words, when a tilt occurs which a laser beam of the pickup unit is not perpendicularly projected with respect to a surface of a disc, a tilt compensator, so called, is provided in the optical recording/reproducing apparatus. The tilt compensator adjusts upwards and downwards a position of the pickup unit to control the level of the pickup unit with respect to a disc.
Such a tilt compensator is structured to adjust the level of the pickup unit with respect to a disc by elevating and lowering a pair of guide shafts according to a tilt degree of the disc in which the pair of guide shafts movably support the pickup unit on a deck base. The tilt compensator of the optical recording/reproducing apparatus as stated above is, however, structured to use an arbitrary standard disc upon assembling the optical recording/reproducing apparatus and to adjust only the level of the pickup unit with respect to the standard disc. That is, during an operation of the optical recording and/or reproducing apparatus, an adjustment of the level of the pickup unit with respect to a seated disc, which is rotated for information recording or reproduction, is impossible. In fact, there is the case that the seated disc is bent upward or downward along the radial direction from its center due to a manufacturing error, etc. Accordingly, as an extreme example, if a disc loaded in the optical recording/reproducing apparatus is tilted in an opposite direction to a disc used for the adjustment of the level of the pickup unit during an assembly of the optical recording/reproducing apparatus, the gap between the disc and the pickup unit is wider or excessively more narrow than the adjusted gap. Therefore, errors upon recording/reproducing information occur, and even worse, the information recording/reproducing may not be achieved. Particularly, the above problem is more serious in the Digital Versatile Disc having a smaller pit than in the compact disc.
An exemplar of the art is Itakura et al. (U.S. Pat. No. 5,978,332, Optical Recording Medium, Tilt Detector, Optical Disk Drive, Tilt Detecting Method, and Tilt Correcting Method, Nov. 2, 1999) discloses using a tracking error signal for detecting the tilt by obtaining the difference in quantities of light received by a photo detector and correcting an error tilt amount detected by the imbalance of the light beam on a mirror surface. Ohmi (U.S. Pat. No. 6,041,030, Optical Disk Recording/Reproducing Device with Eccentric and Incline Chuck Control, Mar. 21, 2000) discloses a chuck to compensate for the tilt angle of an optical disc used for recording. Ichimura et al. (U.S. Pat. No. 6,041,031, Optical Disc Recording/Reproducing Apparatus and Method, Mar. 21, 2000) discloses an optical disc recorder and/or reproducer. Kondo et al. (U.S. Pat. No. 4,502,134, Optical Disc Signal Reproducing System with Tilt Immunization, Feb. 26, 1985) discloses a method of compensating for false tracking correction due to light reflected from the lands as opposed to the pits of a recording medium when the disc is tilted from the optical axis. Namoto et al. (U.S. Pat. No. 5,657,303, Tilt Sensor, Optical Disk, and Tilt Compensating Method for Performing a Stable Tilt Compensating Control, and Apparatus Utilizing the Same, Aug. 12, 1997) discloses a tilt sensor and a tilt compensating mechanism for angularly adjusting the optical pickup to eliminate the tilt. Araki (U.S. Pat. No. 5,909,413, Optical Pickup Apparatus Having Crosstalk Balance and Tilt Correction, Jun. 1, 1999) discloses the generation of a tilt error signal using the information about the inner and outer circumference of a track. Murao (U.S. Pat. No. 5,302,834, Optical Pickup and Tilt Control Device Including a Plurality of Photosensitive Units for Generating Signals Indicating Whether Tilt Correction is Necessary, Apr. 12, 1994) discloses a tilt control device having a parallel flat glass plate for refracting the reflected light beam from the optical system. Ohsato (U.S. Pat. No. 5,153,348, Optical Disk Pickup Device with Tilt Compensation by Electrostriction, May 7, 1996) discloses tilt compensation by electrostriction that makes a mechanical deformation cause by the application of an electric field. Marino (U.S. Pat. No. 5,910,936, Measuring and Compensating for Warp in an Optical Recording Disk, Jun. 8, 1999) discloses compensating for disk warp by calculating the desired tilts of a magnetically suspended actuator while the disk is being read. Kobayashi (U.S. Pat. No. 5,646,916, Track-Lead-In Control Device for Optical Head, Jul. 8, 1997) shows an optical head that can be used for an optical disc and Seidel (U.S. Pat. No. 5,815,480, Method for Calculating and Recording a Start Program Radius Upon a Compact Disc, Sep. 29, 1998) shows a technique for determining the start point for a compact disc recording.
SUMMARY OF THE INVENTION
The present invention is disclosed to solve the aforementioned problems, and accordingly it is an object of the present invention to provide an automatic tilt compensator of an optical recording and/or reproducing apparatus for sensing and automatically compensating for a deformation direction and a deformation degree of a disc which is rotated during an operation of the optical recording and/or reproducing apparatus.
It is another object of the present invention to provide an optical recording and/or reproducing apparatus having the automatic tilt comp
Lee Kyu-hyeong
Lee Young-Won
Park Jong-Pil
Seo Young-Sun
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