Optical pickup device

An optical pickup device for reproducing information from an optical disk having a track which is provided with a groove part which is a recessed part and a land part which is a raised part, in which one main spot, a first subspot, and a second subspot are formed by irradiation of light on the optical disk, said optical pickup device comprising:

• means for generating a push-pull signal which indicates a deviation between each of said spots and the track;
• and
• α selecting means for selecting a value of a variable α such that |SPP1−αSPP2|<Δ, where Δ is a value corresponding to a preset range, a push-pull signal of said main spot is MPP, SPP1 is a push-pull signal of said first subspot, SPP2 is a push-pull signal of said second subspot,
• wherein:
• MPP-β(SPP1+αSPP2) is a tracking error signal, wherein α is fixed as the value selected by said α selecting means and β represents an intensity ratio of said main spot to said first and second subspots.

An optical pickup device for reproducing information from an optical disk having a track which is provided with a groove part which is a recessed part and a land part which is a raised part, in which a main spot of a zeroth-order light beam and one pair of subspots of ±first-order light beams are formed by irradiation of light on the optical disk, said optical pickup device comprising:

• a first diffraction element which forms said main spot and said one pair of subspots which are placed symmetrically with respect to said main spot;
• a second diffraction element which diffracts reflected light, from the optical disk, of said main spot and said one pair of subspots which are formed by said first diffraction element, said second diffraction element being divided by at least a division line in a parallel direction with the track;
• a light receiving element including at least (a) light receiving sections (A and B) for detecting diffracted light of the +first-order light beam from regions which are provided by dividing said second diffraction element by a division line in a parallel direction with the track, and (b) light receiving sections (C and D) for detecting diffracted light of the −first-order light beam from regions which are provided by dividing said second diffraction element by a division line in a parallel direction with the track;
• α selecting means for selecting a value of a variable α such that a difference in absolute value between (As-Bs) and α(Cs-Ds) falls in a preset range when outputs of the light receiving sections (A, B, C, and D) of said light receiving element are denoted as As, Es, Cs, and Ds, respectively;
• and
• L/G operating means for operating (As-Es)−α(Cs-Ds) as a land/groove discriminating signal, wherein α is fixed as the value selected by said α selecting means.

An optical pickup device for reproducing information from an optical disk having a track which is provided with a groove part which is a recessed part and a land part which is a raised part, in which a main spot of a zeroth-order light beam and one pair of subspots of ±first-order light beams are formed by irradiation of light on the optical disk, said optical pickup device comprising:

• a first diffraction element which forms said main spot and said one pair of subspots which are placed symmetrically with respect to said main spot;
• a second diffraction element which diffracts reflected light, from the optical disk, of said main spot and said one pair of subspots which are formed by said first diffraction element, said second diffraction element being divided by at least a division line in a parallel direction with the track;
• a light receiving element including at least (a) light receiving sections (A and B) for detecting diffracted light of the +first-order light beam from regions which are provided by dividing said second diffraction element by a division line in a parallel direction with the track, (b) light receiving sections (C and D) for detecting diffracted light of the −first-order light beam from regions which are provided by dividing said second diffraction element by a division line in a parallel direction with the track, and (c) light receiving sections (E and F) for detecting diffracted light of the main spot from regions which are provided by dividing said second diffraction element by a division line in a parallel direction with the track;
• α selecting means for selecting a value of a variable α such that a difference in absolute value between (As-Bs) and α(Cs-Ds) falls in a preset range when outputs of the light receiving sections (A, B, C, D, E, and F) of said light receiving element are denoted as As, Bs, Cs Ds_Es, and Fs, respectively;
• and
• TES operating means for operating (Es-Fs)−β[(As-Bs)+α(Cs-Ds)] as a tracking error signal, wherein α is fixed as the value selected by said α selecting means and β represents an intensity ratio of said main spot to said first and second subspots.