US Patent 7366069 Auto-adjusting system for an optical incident angle

An auto-adjusting system for an optical incident angle comprises a memory, a linear tilt calculation unit, a non-linear tilt calculation unit, a controller, and a tilt actuator. The memory is used for storing a linear tilt compensation table and a non-linear tilt compensation table. The linear tilt calculation unit is used for calculating the corresponding linear tilt dac value by consulting the linear tilt compensation table according to a first radius and a focus output voltage. According to a predetermined comparison procedure, the non-linear tilt calculation unit is used for generating a second radius wherein the compact disc begins to generate non-linear deformation and then obtaining the corresponding non-linear tilt compensation parameter by consulting the non-linear tilt compensation table according to the first radius and the second radius. The controller is used for controlling the pickup head, the memory, the linear tilt calculation unit, and the non-linear tilt calculation unit.