Tracking error signal generation device

A tracking error signal generation device used for an optical pickup device capable of reproducing and/or recording an information signal on a spiral or coaxial signal track of a disk shaped optical record medium of one type among a plurality of optical record media of different types which track pitches are different from each other,

• said optical pickup device comprising:
• a light beam irradiation means for irradiating the optical record medium with a main beam for forming a main beam spot on the signal track, a first sub beam for forming a first sub beam spot on the optical record medium ahead of the main beam spot and a second sub beam for forming a second sub beam spot behind the main beam spot;
• a first light detection means having at least two light receiving surfaces which are divided by a boundary line substantially parallel to a tangent direction of the signal track for receiving a reflection light of the first sub beam and outputting first and second light detection signals S1 and S2 indicating light amounts received by the two light receiving surfaces thereof respectively;
• a second light detection means having at least two light receiving surfaces which are divided by a boundary line substantially parallel to the tangent direction for receiving a reflection light of the main beam and outputting third and fourth light detection signals S3 and S4 indicating light amounts received by the two light receiving surfaces thereof respectively;
• and
• a third light detection means having at least two light receiving surfaces which are divided by a boundary line substantially parallel to the tangent direction for receiving a reflection light of the second sub beam and outputting fifth and sixth light detection signals S5 and S6 indicating light amounts received by the two light receiving surfaces thereof respectively,
• said tracking error signal generation device comprising:
• a first operation means, to which the first, second, fifth and sixth light detection signals S1, S2, S5 and S6 are inputted, for adding the first and second light detection signals S1 and S2 to output its result as a first addition signal, adding the fifth and sixth light detection signals S5 and S6 to output its result as a second addition signal, and subtracting one of the first and second addition signals from the other to output its result as a first tracking error signal according to a three beam method;
• and
• a second operation means, to which the first to sixth light detection signals S1 to S6 are inputted, for calculating a second tracking error signal SE according to a DPP (Differential Push Full) method expressed by an expression (1), in case that the light receiving surfaces respectively corresponding to the first and fifth light detection signals S1 and S5 are arranged on one straight line including the radius of the optical record medium at positions corresponding to directions same to each other of the signal track with respect to the boundary line, and that the light receiving surfaces respectively corresponding to the second and sixth light detection signals S2 and S6 are arranged on another straight line including the radius of the optical record medium at positions corresponding to directions same to each other of the signal track with respect to the boundary line,
• SE={(S1+S5).+-.(S2+S6)}.times.K.+-.(S3.+-.S4) (1)
• wherein K is a predetermined constant set in advance, and signs of the .+-.s are same to each other for each calculation,
• said tracking error signal generation device further comprising:
• a selecting device for selecting one of the first tracking error signal and the second tracking error signal SE on the basis of an instruction from the external, and outputting the selected signal as an output tracking error signal.