Dynamic information storage or retrieval – Storage medium structure – Adjuncts or adapters
Reexamination Certificate
2000-03-01
2003-07-15
Psitos, Aristotelis M. (Department: 2753)
Dynamic information storage or retrieval
Storage medium structure
Adjuncts or adapters
C365S053000
Reexamination Certificate
active
06594225
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an information recording/reproduction apparatus, such as a DVD, CD-ROM, CD, CD-R, or LD apparatus, which has a mechanism which tightly fastens the disc between a turntable and a clamper when an information recording disc, such as DVD, CD-ROM, CD, CD-R or LD, is rotated, and a rotation monitoring mechanism for the information recording disk assembled into the information recording/reproduction apparatus.
The DVD apparatus, for example, has been provided with a rotation monitoring mechanism for monitoring a rotation state of a DVD as an information recording disc.
A main role of the rotation monitoring mechanism is to generate a signal which is utilized for checking as to if the DVD has reliably been stopped in rotation after a STOP/EJECT button is pushed with intention of taking the DVD out of the apparatus.
Another role of the rotation monitoring mechanism is to generate a signal which is utilized for checking as to if the rotational speed of the DVD, for example, is abnormally high.
Yet another role of the rotation monitoring mechanism is to generate a signal utilized for the rotation servo system.
FIG. 2
shows a first related rotation monitoring mechanism designed for performing those roles, which indirectly detects a rotation state of a disc (DVD)
990
by detecting a rotation state of a turntable
910
for supporting and rotating the disc
990
. The related rotation monitoring mechanism includes the turntable
910
, a magnetic sensor
940
mounted on a small board
930
, which is located in a small gap between the turntable and the upper face of a DC motor
920
for driving the turntable
910
, and magnets (not shown) which are circularly buried in the lower face of the turntable
910
at a predetermined pitch so as to pass through right above the magnetic sensor
940
when the turntable
910
is rotated.
In
FIG. 2
, reference numeral
970
is a damper of which the cross section is shaped like H laid laterally. The disc
990
is tightly fastened between the damper
970
and the turntable
910
. Usually, the front loading type DVD apparatus includes such damper
970
.
A recess
972
into which a top portion of protrusion
910
a
formed on the central portion of the turntable
910
is to be inserted is formed in the lower side of the camper
970
. Usually, a magnet
971
(or any other metal plate, e.g., an iron plate, magnetically attracted) is buried in the bottom of the recess
972
. An iron plate
910
a
1
(or magnet) is attached to the top face of a protrusion
910
a
of the turntable
910
. The magnet
971
and the iron plate
910
a
1
bring the camper
970
into press-contact with the turntable
910
magnetically (or by the utilization of a magnetic attraction force) in order to firmly hold the disc
990
being fastened between the damper
970
and the turntable
910
.
Reference numeral
980
designates a chucking plate for rotatably holding the damper
970
. A main board, not shown, (usually provided separately from the small board
930
) of the DVD apparatus is provided under the DC motor
920
.
The user sets a disc
990
on a tray (not shown) of the front loading mechanism of the DVD apparatus. Then, the container with the disc located thereon transports the disc
990
to a predetermined position in the innermost part of the apparatus. Thereafter, the DC motor
920
, the turntable
910
, and the board
930
, which have been at locations not in contact with the tray in the lower part of the apparatus, are lifted by a lifting mechanism through an opening formed in the tray up to a predetermined position such that a supporting face of the turntable
910
for the disc
990
is situated above the tray.
At this predetermined position, the turntable
910
supports the disc
990
instead of the tray. The bottom face of the damper
970
is pressed against the top face of the central part of the disc
990
. That is, the disc
990
is tightly fastened between the turntable
910
and the damper
970
.
Namely, the magnetic sensor
940
in the first related rotation monitoring mechanism detects a rotation state of the turntable
910
in the form of variation of a magnetic field developed from the magnet of the rotation monitoring mechanism, which is provided in the bottom face of the turntable
910
.
In the first related rotation monitoring mechanism thus constructed, where a length of a rotary shaft
921
of the DC motor
920
is long, the motor rotation is unsteady. To avoid this, the length of the rotary shaft is selected to usually be short, about 5 mm. It is necessary that the diameter of the turntable
910
is selected so that it does not cover an information recording area of the disk
990
. Further, the DC motor
920
is required to generate a torque large enough to turn the disc
990
. Accordingly, the diameter of the DC motor
920
is selected to be substantially equal to that of the turntable
910
. For this reason, the magnetic sensor
940
mounted on the small board
930
is located in a small gap of about 5 mm wide between the turntable
910
and the upper face of the DC motor
920
for driving the turntable
910
, in order to detect a variation of a magnetic field developed from the magnet provided on the bottom face of the turntable
910
. This necessitates the use of an expensive Hall element for the rotation detector that may be mounted on the small board
930
(viz., the magnetic sensor
940
consists of a Hall element.).
Thus, the rotation monitoring mechanism rejects the use of a relatively inexpensive photo sensor, but requires the use of an expensive Hall element (in some cases, additional circuits, for example, an amplifier for amplifying a weak signal output from the Hall element). Further, the small board
930
on which the Hall element is mounted is separated from the main board since a positional limitation is present for the sensor mounting and it must be designed to be movable. This fact presents a hindrance to the effort of reducing the cost to manufacture.
A second related rotation monitoring mechanism is disclosed in Japanese Patent Publication No. 7-56726A. In the mechanism, a synchronizing mark is attached to the disc in advance. It is used for detecting a rotation state of the disc per se. In the rotation monitoring mechanism, a photo sensor for detecting the synchronizing mark is provided at a position under the disc, outside the DC motor for driving the disc, and relatively close to a position where the synchronizing mark passes through.
The second related rotation monitoring mechanism allows the use of a relatively inexpensive photo sensor, but it is disadvantageous in that the synchronizing mark is indispensably attached to the disc. This leads to increase of manufacturing cost. Further, the rotation monitoring mechanism is incapable of monitoring a disc not having the synchronizing mark. Further, the board on which the photo sensor is mounted is required in addition to the main board since a positional limitation is present for the sensor mounting. This fact presents a hindrance in realizing cost reduction.
A third related rotation monitoring mechanism shown in FIGS. 3 and 4 is disclosed in Japanese Utility Model No. 3060766. In the figure, members similar to the first related art are designated by the same reference numerals used for explaining the first related art, and detailed explanation is omitted.
In the mechanism, windows
1173
A and shield portions
1173
B are alternately and circularly formed on a damper
1170
at a predetermined pitch as a detected member
1173
. A photo emitter
1140
A and a photo detector
1140
B are respectively fitted into a holder
1140
C to constitute a-sensor unit
1140
. A reflector
1180
is arranged at an intersection of optical axes of the photo emitter
1140
A and the photo detector
1140
B so that light emitted from the photo emitter
1140
A and passed through one of the windows
1173
A is reflected to be detected by the photo detector
1140
B. A shield wall
1140
C
1
is provided between the photo emitter
1140
A and the photo detector
Funai Electric Co. Ltd.
Morgan & Lewis & Bockius, LLP
Psitos Aristotelis M.
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