Optical disk player having tilt servo control absent tilt sensor

An optical disk player, comprising:

• a pickup having an objective lens for converging an irradiated light beam on an information recording surface of a disk and with a photodetector for receiving a reflected light beam from said information recording surface through the objective lens, said objective lens and said photodetector being integrally and movably arranged;
• a tracking servo unit operating on a tracking error signal produced by a time difference detection method, said tracking servo unit comprising a servo loop, said servo loop including means for generating said tracking error signal by detecting a phase variation component of output signals of said photodetector varying with the deviation of said irradiated light beam spot in a radial direction of the disk relative to a recording track of the disk, and means for deviating said irradiated light beam spot in the radial direction of the disk according to the tracking error signal;
• and
• a tilt servo unit for controlling said irradiated light beam so as to be perpendicular to an optical axis of said information recording surface according to a disk tilt detecting signal, said tilt servo unit comprising disk tilt detecting means responsive only to said photodetector for generating the disk tilt detecting signal by detecting the tilt of said information recording surface relative to the optical axis of said irradiated light beam;
• wherein said photodetector consists of at least a pair of photoelectric conversion elements arranged so that said photodetector is divided into two parts along the direction of said recording track, and said disk tilt detecting means issues a differential output of light receiving outputs of said pair of photoelectric conversion elements when said servo loop of said tracking servo unit is in a closed state for generating said tracking error signal and issues said differential output as said disk tilt detecting signal.