Abstract: An optical disk 100 is provided with a hub 3 at the central portion of a substratel. A relationship Y/X?0.015, preferably Y/X?0.05 is satisfied where X is the projected area of the substrate 1 and Y is a contact area between the hub 3 and the substrate 1. As result, no slippage occurs between the hub 3 and the substrate 1 even when they are rotated at high speed than conventional. With this higher rotational speed, the data transfer rate is improved, and irregular rotation and the camming are suppressed, thereby reducing tracking errors and write/read errors.

Abstract: A corrugating roller unit is moved smoothly between a first reference plane and a second reference plane at different heights by a roll-out apparatus having a set of moving support device. A first moving support device supports the corrugating roller unit when the corrugating roller unit is in contact with the first reference plane. A second moving support device supports the corrugating roller unit when the corrugating roller unit is in contact with the second reference plane. A positioning device keeps the second moving support device in contact with the second reference plane when the second moving support device is providing the support for the corrugating roller unit. When the second moving support device moves the second reference plane to the first reference plane, the positioning device prevents the second moving support device from restricting movement of the corrugating roller unit.

Abstract: A disclosed multiple rotating absolute encoder comprises an encoding plate with a first pattern and a second pattern formed thereon, a first detection unit for reading the first pattern and outputting an information in one rotation of the encoding plate, a second detection unit for reading the second pattern and outputting a first rotation information of the encoding plate, a calculation unit for calculating a second rotation data based on the information in one rotation and the first rotation data, a selection unit for monitoring a rotation speed of the encoding plate and selecting either the first rotation data or the second rotation data in accordance with the rotation speed, and a data calculation unit for calculating rotation information of the encoding plate on the basis of either the first rotation data or the second rotation data selected by the selection unit and the information in one rotation.

Abstract: An encoder includes a code plate, a detector, a transformer, and first and second calculators. The code plate is formed with an absolute pattern including a plurality of bit patterns, each bit pattern formed by a predetermined number of bits and representing one absolute position. The detector moves relatively with respect to the code plate, has a plurality of detecting elements arranged to be opposed to the predetermined number of bits, and reads the bit pattern from the absolute pattern to output a bit pattern signal representing the bit pattern. The transformer can transform only specific bit pattern signals corresponding to specific bit patterns out of a plurality of the bit pattern signals corresponding to the plurality of bit patterns, into the absolute positions. The first calculator calculates a relative, positional relation between the bit pattern corresponding to the bit pattern signal, read from the detector, and the specific bit pattern.