Dynamic information storage or retrieval – Storage medium structure – Adjuncts or adapters
Reexamination Certificate
1998-06-10
2001-10-23
Miller, Brian E. (Department: 2153)
Dynamic information storage or retrieval
Storage medium structure
Adjuncts or adapters
C360S133000
Reexamination Certificate
active
06307831
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a disc cartridge for a minidisc (MD) or the like having a disc-like medium such as an optical disc or the like received therein, and more particularly to such a disc cartridge of a three-piece structure wherein an upper plate and a lower plate are joined to each other through a center frame interposedly arranged therebetween.
A disc cartridge which has been conventionally known in the art is generally constructed in such a manner as shown in
FIG. 1
by way of example. More particularly, a conventional disc cartridge generally designated at reference numeral
100
in
FIG. 1
includes a lower plate
110
and an upper plate
150
securely joined to each other by means of screws
186
while being superposed on each other and having a disc-like medium
170
received therebetween, resulting in being constructed into a two-piece structure.
The lower plate
110
and upper plate
150
of the disc cartridge
100
are respectively formed with openings
111
and
151
through which a recording/reproducing head of an information recording/reproducing apparatus or the like is inserted into the disc cartridge to carry out recording/reproducing of data with respect to the disc-like medium
170
. The disc cartridge
100
includes a shutter
180
of a substantially U-shape in section arranged so as to render the openings
111
and
151
open when the head or the like is inserted therethrough and closed otherwise. The shutter
180
is provided on both ends thereof with engagements
181
, through which the shutter
180
is engaged with both upper and lower plates
150
and
110
. The lower plate
110
is provided thereon with a shutter lock
153
for locking the shutter
180
at a position at which the shutter
180
closes the openings
111
and
151
.
Also, the upper and lower plates
150
and
110
are formed on a side surface thereof with depressions or recesses
152
and
112
, which cooperate with each other to provide a labeling region when both plates are joined together.
The upper plate
150
is provided thereon with a shutter slide region
153
including the opening
151
. The shutter slide region
153
is formed into a reduced thickness so that an outer surface of the shutter
180
and that of the upper plate
150
are flush with each other when the shutter is mounted on the upper and lower plates
150
and
110
. This is also true of the lower plate
110
.
The upper plate
150
is provided with a gate
154
for molding thereof, which is located in the shutter slide region
153
. A failure in cutting of the gate
154
leads to occurrence of burrs. This would deteriorate satisfactory sliding of the shutter
180
and leads to occurrence of shavings, to thereby causes dropout. In order to avoid the possible problem, the gate
154
is formed in a manner to be depressed from an outer surface of the shutter slide region
153
. Also, in order to ensure satisfactory flowing of resin during molding of the upper plate
150
, the upper plate
150
is formed at a portion of an inner surface thereof positionally corresponding to the gate
154
with a projection-like cold slug well (not shown).
It is generally required that the disc cartridge
100
is formed so as to exhibit rigidity or durability sufficient to ensure outdoor use thereof. Such an increase in rigidity would be attained by increasing a thickness of the upper and lower plates
150
and
110
. Unfortunately, this causes occurrence of a sink mark, leading to a deterioration in appearance of the disc cartridge.
In view of the foregoing, a disc cartridge which is constructed into such a three-piece structure as shown in
FIG. 2
is proposed as disclosed in Japanese Patent Application Laid-Open Publication No. 78478/1989. More specifically, the disc cartridge generally designated at reference numeral
200
includes an upper plate
250
, a lower plate
210
, and a center frame
230
interposedly arranged between the upper plate
250
and the lower plate
210
, resulting in exhibiting increased rigidity.
Thus, the conventional disc cartridge is constructed into a three-piece structure when it is required to exhibit increased rigidity and massive properties. Otherwise, it is constructed into a two-piece structure.
In the conventional disc cartridge
200
shown in
FIG. 2
, the center frame
230
is provided on a peripheral portion of each of upper and lower surfaces thereof with a stepped portion
231
of an L-shape in section, in which a side surface of each of the upper plate
250
and lower plate
210
is fitted, to thereby permit each of the upper and lower surfaces of the disc cartridge assembled to be flat. Unfortunately, such construction causes a boundary line between the center frame
230
and each of the upper and lower plates
250
and
210
to be formed on each of the upper and lower surfaces of the disc cartridge assembled. Such a boundary line causes a difference in level, often leading to a failure in smooth loading and unloading of the disc cartridge with respect to an information recording/reproducing apparatus.
In the conventional disc cartridge shown in
FIG. 1
, as described above, the labeling region to which a label is applied includes a mating line defined between the upper plate
150
and the lower plate
110
as well as the depressions
152
and
112
thereof, to thereby often fail to be flat and tend to be stepped. Formation of such a stepped portion leads to a failure in satisfactory labeling and causes a label adhered to the labeling region to be easily removed therefrom.
The disc cartridge of a three-piece structure shown in
FIG. 2
eliminates the above-described problem relating to labeling; because the upper plate
250
and lower plate
210
are fitted at the outer periphery thereof in the stepped portions
231
formed on the inner periphery of the upper and lower surfaces of the center frame
230
, to thereby render a side surface of the disc cartridge
200
free from any mating line. Instead, such construction of the disc cartridge causes a mating line between the center frame
230
and the plates to be defined in proximity to an outer edge of the upper and lower surfaces of the disc cartridge. This often fails in proper positioning of the disc cartridge in the information recording/reproducing apparatus and causes the disc cartridge to be caught in the apparatus.
In general, the upper and lower plates are made of polycarbonate (PC) resin, to thereby exhibit satisfactory sliding properties. However, the center frame is required to be made of a material increased in rigidity. This generally causes the center frame to be made of a material different from that of the upper and lower plates, resulting in the center frame being deteriorated in sliding properties depending on the material. When the center frame fails to exhibit satisfactory sliding properties, contacting of the shutter with at least a part of the center frame during sliding movement thereof causes the shutter to be deteriorated in operation. In order to improve a design or appearance of the disc cartridge, it is often practiced to make the upper and lower plates of a transparent material to permit the center frame to be externally visible and color the center frame by painting or plating. Contacting of the shutter with the center frame during the sliding movement causes a colored layer formed on the center frame to be peeled therefrom as well as the above-described deterioration in operation of the shutter.
In order to keep the shutter from being in contact with the center frame to eliminate the above-discussed problem, it would be considered that the center frame is formed into a substantially C-shape, resulting in being excluded or removed from a location in proximity to a region of sliding of the shutter. However, this fails to increase rigidity of the center frame.
Such exclusion of the center frame from the region of sliding of the shutter reduces strength of the upper and lower plates, leading to cracking or breakage of the disc cartridge, because a portion of each of the upper and lower
Ikebe Masaru
Miyazaki Yukio
Okamura Masatoshi
Fields Kenneth W.
Lerner David Littenberg Krumholz & Mentlik LLP
Miller Brian E.
TDK Corporation
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