1. Field of the Invention
The present invention relates to a disc apparatus for reproducing, recording or erasing a magnetic disc or an optical disc represented, for example, by a DVD (Digital Versatile Disc) (hereinafter simply referred to as a disc) and, more specifically, to a lock mechanism of a pick-up unit mounted on such a disc apparatus.
2. Description of the Background Art
Generally, a disc apparatus includes, in its main body, a disc tray conveying a disc, and a drive unit movable in a direction approximately vertical to the direction of conveying the disc tray. The drive unit includes a pick-up unit having a pick-up for recording or reproduction of the disc, and a motor for moving the pick-up unit along radial direction of the disc.
A transmitting portion including a plurality of gears is provided on the motor, for reducing and transmitting the driving force of the motor. When the transmitting portion meshes with a rack formed in the pick-up unit, the pick-up unit can be moved by the motor.
Further, the transmitting portion can be meshed with an elevating mechanism arranged on the main body of the apparatus. The elevating mechanism is engaged with the drive unit by means of a cam, and movable in the direction of conveying the disc tray and the direction approximately orthogonal to the elevating (up/down) direction of the drive unit. Thus, the drive unit is moved upward/downward. Further, the transmitting portion can be meshed with a rack formed in the disc tray, and at a prescribed timing, the transmitting portion is coupled with the disc tray, so that the driving force of the motor is transmitted to the disc tray.
When a disc is placed on the disc tray in the disc apparatus having the structure described above, the disc tray is conveyed into the disc apparatus by the motor drive. When the disc tray is positioned in place, coupling between the disc tray and the transmitting portion is released, while the elevating mechanism is coupled with the transmitting portion. The elevating mechanism moves in a direction vertical to the conveying direction of the disc tray, so that the drive unit is moved upward. Thus, the disc engages with a chuck portion provided in the drive unit.
After the disc is chucked, coupling between the transmitting portion and the elevating mechanism is released, and the transmitting portion is coupled to the pick-up unit. This allows movement of the pick-up unit along the radial direction of the disc, and therefore, recording or reproduction at a prescribed position of the disc becomes possible. The disc can be taken out by an operation reverse to that described above.
In the disc apparatus having the above-described structure, it becomes necessary to lock, by a lock mechanism, the pick-up unit to prevent movement thereof in a state where the disc tray is drawn forth. By locking the pick-up unit, the start position of the pick-up unit with respect to the motor can be determined. This prevents positional deviation of the pick-up unit by fluctuation of the disc apparatus and hence prevents any resulting malfunction.
The pick-up unit locking mechanisms are disclosed, for example, in Japanese Patent Laying-Open Nos. 2003-085855, 2002-329361 and 2000-011511 as well as in Japanese Utility Model Registration No. 3095688. Among these, Japanese Patent Laying-Open No. 2000-011511 discloses a lock mechanism in which a lever member to be meshed with the pick-up unit when the drive unit is lowered is urged by an elastic body to attain locking of the pick-up unit.
In the disc apparatus disclosed in Japanese Patent Laying-Open No. 2000-011511, however, a lever member and the elastic body are required for locking the pick-up unit, and therefore, the number of components is increased and the apparatus becomes larger. The disc apparatuses disclosed in Japanese Patent Laying-Open Nos. 2003-085855 and 2002-329361 and in Japanese Utility Model Registration No. 3095688 also have the problem that the structure of the apparatus becomes complicated or the number of components increases.