COARSE POSITION ERROR SIGNAL GENERATION IN AN OPTICAL DISK STORAGE SYSTEM EMPLOYING COURSE SERVO TRACKS

摘要

ABSTRACT OF THE DISCLOSUREA linear detector (61) for use in a coarse positioning servosystem of an optical system. The linear detector produces an errorsignal having an amplitude linearly proportional to the distancethat a relatively narrow strip of light energy (63) falls on acollection surface (62) of the detector as measured relative to afixed reference point on said collection surface. Two referencesignals (65, 66) are derived from circuitry associated with thecollection surface. A first reference signal (65) has an amplitudeproportional to the intensity of the focused light energy and thelocation that said light energy falls on the collection surfacerelative to a first reference point. A second reference signal (66)has an amplitude proportional to the intensity of the focussed lightenergy and the location that said light energy falls on thecollection surface relative to a second reference point. The sumand difference of the amplitudes of the first and second referencesingles are derived to produce sum and difference signals,respectively. The difference signal is divided by the sum signal toproduce the desired error signal (67), which error signal has anamplitude that is substantially independent of the intensity of thefocused light energy.