Beam position detecting device for optical disc apparatus

Claim 1

A beam position detecting device for an optical disc apparatus which records and reads information on and out of an optical disc by radiating a light beam from a moveable optical head onto the optical disc, comprising: a photosensor supported at a fixed position spaced apart from the optical head and including a plurality of photoelectric elements arranged in a line in the radial direction of the optical disc; a beam splitter integrally formed with the optical head for splitting a light beam reflected from the optical disc and directing a portion of the reflected light beam toward said photosensor; means for driving said beam splitter together with the optical head and in the radial direction of the optical disc, wherein said photosensor is scanned by the portion of the reflected light beam from said beam splitter so that the photoelectric elements of said photosensor sequentially produce photoelectric signals; readout means for sequentially reading out the photoelectric signals from said photosensor and for producing an initial address signal; and light beam position detecting means coupled to said readout means and including a sampling pulse signal generator for generating sampling pulse signals in response to the photoelectric signals, a sawtooth signal generator for generating a sawtooth signal in synchronism with the initial address signal of said readout means, means for sampling the sawtooth signal from the sawtooth signal generator in response to the sampling pulse signals from said sampling pulse signal generator and for producing a corresponding sawtooth signal component, and judging means for determining the position of the light beam in accordance with the sawtooth signal component.