| 摘要 |
<p>The invention relates to a device for reading and/or writing a disc-shaped information carrier (17), which comprises a support element (25) of a magnetizable material along its circumference. The device comprises an electromagnetic unit (27) for co-operation with the support element and a scanning unit (23) for reading and/or writing the information carrier. By co-operation between the electromagnetic unit and the support element, the information carrier can be rotated about an axis of rotation (73) and positioned with respect to the scanning unit (23) in five degrees of freedom, i.e. in all degrees of freedom except the rotational degree of freedom around the axis of rotation. According to the invention, the electromagnetic unit (27) comprises a single pair of rows (29, 31) of electromagnets (33, 35), which rows are arranged, along an X-axis perpendicular to the axis of rotation (73), on both sides of the information carrier. The electromagnetic unit (27) further comprises a first pair of electromagnets (37, 39) and a second pair of electromagnets (41, 43) which are diametrically arranged with respect to each other, viewed in a middle position of the information carrier (17) along the X-axis and viewed along a Y-axis perpendicular to the X-axis and the axis of rotation, the magnets of the first and the second pair being arranged on both sides of the information carrier, and the magnetic poles (69, 71) of the electromagnets of each pair being arranged at equal distances from the X-axis and, in each position of the information carrier along the X-axis, on one side of a magnetic point of application (M) of the support element. Thus, the electromagnetic unit has a comparatively simple construction and comprises a limited number of electromagnets, so that also the control unit, which is necessary to control the electromagnetic forces of the electromagnets, is simplified.</p> |
