| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a FPD (Front Photo Detector) having no gain selecting switch, an optical pickup device including it, and an optical recording and reproducing device. <P>SOLUTION: The FPD of an optical pickup consists of an optical device in which directions of light emitted from a plurality of laser diodes are different, a photodiode part constituted of respective photodiodes receiving light emitted from respective laser diodes and passing through the optical device, respective current voltage amplifying circuits converting output current from respective photodiodes to voltage, and a voltage amplifying circuit in which amplification gain for output from respective current voltage amplifying circuit can be set separately. Thereby, as a gain selecting switch is not required, structure becomes simple, and reliability is improved without causing malfunction due to an error caused at the time of gain selection. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
