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AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsKyosuke Yoshimoto, Kyouji Shimoda
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An optical data medium driving apparatus which constitutes amplifiers for an output current signal of a photosensor including a plurality of current mirror circuits having different amplification factors in order to switch, in a wide range, the output current signal of the photosensor. The photosensor detects a quantity of the reflected light corresponding to a variation of the quantity of reflected light from an optical data medium having various characteristics. The output is obtained with high accuracy and in a wide band. A servo-circuit is used for an AGC circuit and normalizes a difference signal from each light receiving surface at a photosensor having a plurality of light receiving surfaces. An A/D converter is given the difference signal as an analog input signal and the sum signal as the reference input signal. The A/D converter outputs an offset binary type digital signal, thereby being inexpensive to produce, easy to be integrated having high function, and high in reliability.
An optical data medium driving apparatus and a servo circuit, comprising:
An optical data medium driving apparatus and a servo circuit, comprising a photosensor which outputs a current signal corresponding to a quantity of transmitted light or reflected light from an optical data medium, an amplification means, means coupling the output current signal from said photosensor to said amplification means, said amplification means comprising a current mirror circuit including a plurality of switching elements, and means for intercoupling the switching elements so as to provide respective element current signals that are equal to the photosensor output current signal while combining selected ones of said element current signals to thereby provide amplification of said photosensor output current signal.
An optical data medium driving apparatus and a servo circuit, comprising:
An optical data medium driving apparatus and a servo circuit, comprising:
Dependencies are inferred from the claim text.