Error signal detecting apparatus for optical recording/reproducing apparatus

A method of detecting error comprising:

• adding a detection signal of a first inner light receiving area and detection signals of third and fourth outer light receiving areas to generate a first addition signal, the first inner light receiving area being on an opposite side of an axis in a radial direction of a recording medium from the third and fourth outer light receiving areas;
• adding a detection signal of a second inner light receiving area and detection signals of first and second outer light receiving areas to generate a second addition signal the first and second inner light receiving areas, the second inner light receiving area being on an opposite side of the axis from the second and first outer light receiving areas;
• and
• subtracting the first and second addition signals to generate a tangential tilt error signal.

A method of detecting error comprising:

• subtracting a detection signal of a first inner light receiving area and a detection signal of a second inner light receiving area to generate a first subtraction signal, the first inner light receiving area being on an opposite side of an axis in a radial direction of a recording medium from the second inner light receiving area;
• subtracting a sum signal of detection signals of first and second outer light receiving areas and a sum signal of detection signals of third and fourth outer light receiving areas to generate a second subtraction signal;
• and
• adding the first and second subtraction signals to generate a tangential tilt error signal.