| 摘要 |
<p>The video disc drive has a conical hub to centre the disc and a mechanical key which is engaged in a slot in the disc to provide positive drive. A sleeve (13) holding the disc drive motor is raised or lowered to raise or lower the disc for reading or removal. When it is raised a second sleeve (14), free to slide along the first sleeve (13), is forced downwards by spring pressure (20,23) allowing the disc key (21) to pass through a slot in the disc. When the drive motor is lowered, the outer sleeve (14) is prevented from following it fully down by a stop (16) on a fixed frame (18). This pivots (22) the disc key which tilts back into a slot in the conical hub (3), freeing the disc. To improve disc centreing on the hub, several flexible metal springs in the form of fingers are provided in slots in the hub. One end terminates in a moving plate (19) held away from the hub (3) by a spring (20), the other slides along the conical bottom of the slot as the motor is raised. These fingers bend outwards to lightly touch the inside of the disc hole as the hub is raised to enhance centreing.</p> |
