1. Field of the Invention
The present invention relates to a disk cartridge in which a disk-shaped recording medium such as an optical disk or a magnetic disk is housed rotatably relative thereto, and particularly relates to a shutter mechanism of the disk cartridge of a type in which a shutter thereof is slidable in both right and left directions from a neutral position at which a head access opening of the disk cartridge is closed by the shutter.
2. Description of the Related Arts
A cartridge case of a conventional disk cartridge, housing a disk-shaped recording medium such as a compact disk or the like therein, has a head access opening for access of a head. The head access opening is openable and closable by a shutter which is slidably mounted on a surface of the cartridge case. When the disk cartridge is loaded inside a disk drive system, the shutter of the disk cartridge is slid by a shutter drive pin of the disk drive system. This allows the shutter to open the head access opening so that the reading and/or writing relative to the disk-shaped recording medium is performed.
Meanwhile, there has been conventionally provided a disk cartridge which accommodates a disk-shaped recording medium that is readable and writable on both sides thereof, and which is possible to be set inside a disk drive system whichever either side thereof comes on top. In order to avoid any complication of the shutter drive mechanism on a side of the disk drive system, the shutter of the disk cartridge is so constructed as to be slidable in both right and left directions from a neutral position at which the head access opening is closed by the shutter, while the shutter drive pin of the disk drive system is so constructed as to be driven in one direction.
As this type of shutter mechanism, for example, Japanese Laid-Open Patent Publication No. 5-6758 discloses a disk cartridge with a shutter mechanism with the following construction.
That is, the disk cartridge has:
a shutter which is slidable relative to the cartridge case in which the shutter has a first slider able to be guided by a sliding groove, as guide means, that is formed on the cartridge case; PA1 a stopper installed at a middle position relative to the cartridge case; PA1 a pair of second sliders which are slidable on both sides of the stopper; and PA1 a pair of torsion coil springs, as biasing means, which are mounted on both sides of the stopper and which bias the sliders inward to each other, PA1 wherein the shutter has a pair of claws which are formed bent inward from a operational opening so that each claw contacts an inner surface of each second slider when both the second sliders contact the stopper.
With the mechanism, when the shutter is not driven by a disk drive system, the shutter remains at its neutral position with the shutter being biased to each other by the pair of torsion coil springs. On the other hand, when the shutter is slid, for example, in the right direction from the neutral position, the shutter is moved together with the right second slider in the right direction while the right torsion coil spring is being deformed or charged, whereas the left second slider remains stationary with the left second slider contacting the stopper. If the shutter is slid in the left direction, the operation is reversed.
According to the mechanism, the first slider of the shutter has only the function to guide the shutter relative to the cartridge case, but does not have the function to be biased or urged by the torsion coil spring as biasing means.
Meanwhile, as another shutter mechanism, there has been proposed a shutter mechanism (see Japanese Patent Publication No. 2508449 as a reference) with a pair of sliders which are able to slide on a metallic guide shaft. The guide shaft is arranged along a direction in which the shutter is slidable, and the pair of sliders are connected to each other with a tension coil spring. The shutter mechanism also has a stopper, formed centrally on the cartridge case, which contacts the pair of sliders from inside in which the stopper has a length that is greater than a free length of the tension coil spring. In the mechanism, the shutter has a pair of projecting parts that contact the two sliders from inside, respectively.
According to the mechanism, the shutter is normally held at the neutral position where the head access opening is closed by the shutter thus biased; on the other hand, the shutter is moved together with one of the sliders at time of sliding the shutter while the other of the sliders remains stationary.
Namely, the shutter mechanism according to the former prior art requires two torsion coil springs; and the shutter mechanism according to the latter related art requires a separate guide shaft, as components, respectively. In other words, the above shutter mechanisms require not a few assembling parts, thus leading to a high cost of production. In addition, shutter mechanism of the latter related art has another problem in which the shutter mechanism has to be assembled in such a way that the slider and shutter need to be first mounted on the separate guide shaft to form a subassembly and then the subassembly needs to be built on the cartridge case. That is, the assembling thereof is hard to perform.