Invention Grant
US08050168B2 Optical head device, optical information device, computer, disc player, car navigation system, optical disc recorder, and vehicle 有权
光头设备,光信息设备,计算机,光盘播放器,汽车导航系统,光盘记录器和车辆

Optical head device, optical information device, computer, disc player, car navigation system, optical disc recorder, and vehicle
Abstract:
An optical head device compatible to different types of optical discs and capable of guaranteeing a sufficiently wide dynamic range for a low density optical disc, and the like are provided.The optical head device includes a plurality of light sources switchably usable; an objective lens for converging light emitted from one of the plurality of light sources to an information recording layer of an optical disc; and a light detector for receiving the light reflected by the information recording layer and outputting an electric signal based on the amount of the received light. The plurality of light sources include a first light source for emitting light having a first wavelength and a second light source for emitting light having a second wavelength shorter than the first wavelength. In the optical head device, a defocus detection range of a focusing error signal obtained based on the light having the first wavelength is set to be wider than a defocus detection range of a focusing error signal obtained based on the light having the second wavelength.
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