Abstract: Provided is an additive for imparting ultraviolet absorbency, or an additive for imparting a high refractive index, which has satisfactory compatibility with a resin serving as a matrix and can maintain high transparency even if added in high concentrations. Also provided is an additive with which the function of imparting both ultraviolet absorbency and a high refractive index can be realized by means of one kind of additive. This additive is represented by the following Formula (I): wherein at least one of R1a to R9a is a monovalent sulfur-containing group represented by the following Formula (i-1) or Formula (i-2): wherein R10a to R12a each represent a divalent hydrocarbon group or the like; and R13a represents a monovalent hydrocarbon group or the like.

Abstract: In a LD player, a phase comparison circuit compares the phases of a horizontal synchronizing signal reproduced from a LD with a reference synchronizing signal to generate a phase error signal having a pulse width according to the phase difference. After the phase error signal is amplified by an equalizer amplifier, this phase error signal is supplied to a motor driving circuit, whereby phase servo control is carried out for the spindle motor. After the start of the reproduction of the disc, a variation amount of the phase error signal during a period corresponding to a predetermined number of rotation of the disc is detected as the eccentricity amount of the rotation of the disc. The duty ratio of the phase error signal is digital-modulated according to the eccentricity amount, whereby the servo gain of the entire servo circuit is corrected to an optimum value.