Abstract: An optical element feeding device driving method and an optical disk apparatus capable of detecting biting in a stepping motor and conducting restoration. The optical disk apparatus includes an optical element feeding device including a movable frame for supporting a spherical aberration correcting lens to move the lens in optical axis direction, a spring for applying force to the frame in the direction, a sensor for detecting a lens reference position, a stepping motor, and a lead screw and a nut for converting motor rotation into the direction, a motor driving circuit, a decision circuit for judging abnormality when an output of the sensor does not change even if the driving circuit outputs a driving signal to the motor after reference position detection, and a changeover circuit for lowering a driving frequency than in ordinary operation, based on an abnormality signal.

Abstract: An optical element feeding device driving method and an optical disk apparatus capable of detecting biting in a stepping motor and conducting restoration. The optical disk apparatus includes an optical element feeding device including a movable frame for supporting a spherical aberration correcting lens to move the lens in optical axis direction, a spring for applying force to the frame in the direction, a sensor for detecting a lens reference position, a stepping motor, and a lead screw and a nut for converting motor rotation into the direction, a motor driving circuit, a decision circuit for judging abnormality when an output of the sensor does not change even if the driving circuit outputs a driving signal to the motor after reference position detection, and a changeover circuit for lowering a driving frequency than in ordinary operation, based on an abnormality signal.

Abstract: A communication cable is provided that satisfies the requirement of Cat.6 for near-end cross talk wherein the difference between the maximum and minimum values of delay time among the four twisted wire pairs constituting the cable is within 25 ns/100 m. The communication cable is made by entwining four twisted wire pairs (T1), (T2), (T3), (T4) made by twisting pairs of insulated wires made by covering electrically conductive wires by polyolefin thermoplastic resin with each pair being twisted with a twist pitch different from the others (pitch: P1<P2<P3<P4) and the inter-pair interposer (6) made of polyolefin thermoplastic resin, while being entwined with each wire pair, around a central interposer (2) made of polyolefin thermoplastic resin having cross sectional area of S1. Cross sectional area S1 of the central interposer (2) satisfies the relationship of inequality S1≧[{4.1 d/(1+{square root over (2)})}·0.

Abstract: A communication cable formed by cabling units such that each two adjacent units have different twist pitches, each unit including insulated wire pairs twisted together. A twist pitch P.sub.i of insulated wire pair T.sub.i selected among insulated wire pairs constituting a unit U.sub.i, and a twist pitch P.sub.j of insulated wire pair T.sub.j selected among insulated wire pairs constituting a unit U.sub.j, are different. Twist pitches P.sub.i and P.sub.j are selected from a region which satisfies expression (1) and either (2) or (3). Twist pitch P.sub.i and twist pitch P.sub.k of insulated wire pair T.sub.k selected among insulated wire pairs constituting a unit U.sub.k, are selected from a region which satisfies expression (4) where twist pitches P.sub.i and P.sub.k are in compliance with prior conditions given by (4).