Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Reexamination Certificate
1997-07-23
2002-02-26
Hindi, Nabil (Department: 2651)
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
C369S047440, C369S053420, C369S053140
Reexamination Certificate
active
06351440
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a disc reproducing method and apparatus which utilize a disc motor for rotating a disc and an optical pickup to realize high speed reproduction, and more particularly relates to a disc reproducing method and apparatus which are suitable for prevention of excessive oscillation and/or vibration in a radial direction of a disc during high speed rotation resulting from an imbalance (e.g., disc eccentricity imbalance, mass imbalance, etc.).
2. Description of Related Art
Use of a so-called compact disc-read only memory (CD-ROM) apparatus (utilizing CD-ROM's as recording/reproduction medium) as a peripheral device of a personal computer has gained in popularity and frequency in recent years. Since introduction, whereupon the CD-ROM apparatus was standardized to operate at a predetermined 1× speed or rate, technology has advanced tremendously, leading to ever increasing operating speeds for the CD-ROM apparatus, i.e., for realization of higher speed data transfer rates. Recently, an 8× speed (i.e., 8 times the original standardized 1× speed) is commonplace, and it is now estimated that high speed data transfer of a 12× speed or higher will become commonplace in the near future.
For background discussion,
FIG. 7
shows a schematic basic block diagram of a servo system used for disc motor control of a disc reproducing apparatus. More particularly, the
FIG. 7
arrangement may be dedicated to reproduce only CD-ROMs on which the information of a computer (hereinafter called CD-ROM information) is recorded, or may also be able to reproduce CDs on which audio information is recorded. If the disc
1
is a CD, the rotational speed is uniquely defined, however, if the disc
1
is a CD-ROM, for example, it can be reproduced at a multiplicity of different speeds, e.g, X times as high as a standardized rotational speed of 1.2 m/sec. More particularly, as described above, recently reproduction at an 8× or 12× rate is mainstream.
Within
FIG. 7
, the information reader
4
(i.e., head arrangement including a laser, lenses, sliders, actuators, etc.) converts information recorded on a disc
1
into an electrical signal and then inputs the signal to a demodulating circuit
6
. The demodulating circuit
6
demodulates the electrical signal and a signal processing circuit
7
generates a clock signal from the demodulated signal. A disc motor servo circuit
8
controls the rotating speed of a disc motor
2
via the disc motor driving circuit
3
so that the clock signal becomes equal to a reference clock signal generated by a reference clock generating circuit
9
.
FIG. 8
shows relationship between a disc reproducing rate multiplication ratio according to a reproducing position and a disc rotating speed. The recording/reproducing system of this exemplary CD-ROM is a constant linear velocity (CLV) system in which linear speed is set to a constant value. In this system, a rotating speed of the disc changes depending on a current reproducing position of the head on the disc. In such discussed CLV system, since a reference rotating speed is 1.2 m/sec in a standard reproducing rate (i.e., in a 1× original standard speed) and a signal recording area of a disc is within a disc region from 25 mm to 58 mm in a radius direction from a center of the disc, for a 4× (i.e., 4-fold) reproducing operation, the rotating speed (frequency) at an innermost position of the 25 mm radius is about 32 Hz as can be seen from the characteristic curve
30
in FIG.
8
. Similarly, in an 8× (i.e., 8-fold) reproducing operation, the maximum rotating speed is about 64 Hz as can be seen from the characteristic curve
31
, and in the 12× (i.e., 12-fold) reproducing operation, the maximum rotating speed is about 96 Hz as can be seen from the characteristic curve
32
.
Turning discussion now to
FIG. 9
, at times., a certain disc
1
which is loaded into and attempted to be reproduced (i.e., read) by a disc reproducing apparatus may have a center of rotation
33
(which is the center of disc
1
) which is deviated from a center of gravity or center of mass point
34
. Such disc situation is hereinafter called a deviated gravity disc. Such deviated gravity disc may be generated during manufacturing, for example, because a disc material pressure is uneven, an unbalanced paint distribution is applied to a surface of the disc, or by reason that an index label is attached on the disc surface after manufacturing thereby to imbalance the disc. When this deviated gravity disc
1
is rotated around the center
33
, a force indicated by a force vector
35
is generated at the point
33
, in a direction of the point
34
. Therefore, when this deviated gravity disc
1
is reproduced by the disc reproducing apparatus, the force
35
works on the disc, disc clamp/mount and disc motor during rotation to fling the disc side to side, and vibration may be generated in a direction matching a major plane of the disc reproducing apparatus. Such situation is called a mass eccentric disc.
The above-mentioned force
35
increases in proportion to a square of the disc rotating speed. Namely, during a reproducing operation in the 8× reproducing rate, a force equal to 4 times that in the 4× reproducing rate is generated, and during a reproducing operation in the 12× reproducing rate, a force equal to 9 times that of the 4× reproducing rate is generated. Therefore, with improvement in a disc reproducing rate (i.e., rotating speed) of the disc reproducing apparatus, vibration generated when a deviated gravity disc is reproduced becomes large. Such vibration can result in a failure of operation (e.g., burn out, mis-reading, etc.) of the disc reproducing apparatus, can have an adverse effect on components installed in close proximity to the vibrating disc, a noise generated therefrom can be an annoyance to a user, and/or vibration can cause the disc reproducing apparatus to move across a surface on which it is placed.
The above-discussed vibration phenomenon is due to a mass eccentricity imbalance of the disc, causable (i.e., presently causing or capable of causing) of at least one of a radial oscillation and radial vibration above a predetermined rotational speed, i.e., oscillation/vibration directed along a radial direction (i.e., in a major plane) of the disc so as to cause a disc to fling side-to-side as the disc is rotated. Such mass eccentricity imbalance is the imbalance of most interest in the present invention. Another imbalance of interest to a smaller degree is a centering eccentricity imbalance, i.e., a centering eccentricity imbalance of the disc, causable of at least one of a radial oscillation and radial vibration above a predetermined rotational speed, i.e., oscillation/vibration directed along a radial direction (i.e., in a major plane) of the disc so as to cause a disc to fling side-to-side as the disc is rotated. Centering eccentricity imbalance results, for example, when a disc is loaded with its disc center misaligned to a center of a rotator arrangement (i.e., rotating motor, disc mount/clamp, etc.). Misalignment may be due to sloppy loading of the disc to the mount/clamp, excessively sized central mounting hole in the disc, excessively small or worn mount/clamp, etc. Centering eccentricity imbalance affects oscillation/vibration and operation of the disc reproducing apparatus to a lesser degree than that of mass eccentricity imbalance. However, the principles and arrangements of the present invention are equally applicable to centering eccentricity imbalance as mass eccentricity imbalance.
Continuing in discussion,
FIG. 14
is a block diagram showing another CD/CD-ROM disc reproducer arrangement, and in greater detail. More particularly, a reference number
1
denotes a disc, T denotes a track or tracks, L denotes a beam (e.g., laser beam),
2
denotes a disc motor,
3
denotes a disc motor driver or control circuit,
4
denotes a head arrangement or informatio
Fukuda Hirotoshi
Ishibashi Hirohito
Matsunaga Toshihiro
Narita Kazunaga
Sano Masato
Antonelli Terry Stout & Kraus LLP
Hindi Nabil
Hitachi Ltd
LandOfFree
Disk reproducing speed control method and a disk reproducing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Disk reproducing speed control method and a disk reproducing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Disk reproducing speed control method and a disk reproducing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2935710