Ricoh Company, Ltd.

Ryohsuke Sugiyama

Masaaki Tsuji

Tsuji Masaaki

An optical disk recording apparatus includes a first comparator, a second comparator, a third comparator, a selection circuit, a control voltage generator, a voltage control oscillator, and a control circuit. The first comparator compares frequency-divided signals to output an error signal. The second and third comparators compare a signal pre-recorded on an optical disk and the frequency-divided signal to output an error signal and a frequency differential signal. The selection circuit selects any one of the error signals to output the signal selected. The control voltage generator generates a control voltage from the signal from the selection circuit. The voltage control oscillator generates and outputs the write reference clock signal having a frequency corresponding to the control voltage from the control voltage generator. The control circuit controls operations of the selection circuit according to the frequency differential signals.

Method and apparatus for optical disk recording capable of reducing settling time and generating an accurate channel clock signal

A write pulse generator is provided with an adjusting section which adjusts a width of write pulses to be generated, a plurality of registers in which control values of adjusting made by the adjusting section are set, a selecting section which selects a control value from the registers and supplies the control value to the adjusting section, and a timing generator. The registers are successively arranged in a plurality of stages so that the control values are successively copied to the registers in subsequent stages. The timing generator generates timings at which the control values are successively copied to the registers in the subsequent stages. The selecting section selects and supplies to the adjusting section the control value held by a register in a final stage.

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Ohsaka-fu, Japan

Ryohsuke Sugiyama