Signal conversion module and optical disc apparatus using the same
AssigneeHitachi Consumer Electronics Co., Ltd.
InventorAtsushi Kikugawa
Life of this patent
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Abstract
In the multi-tone demodulation (MTD) technique, even if an input bandwidth is widened to obtain a larger SNR gain, an increase in the signal to noise ration (SNR) gain cannot always be obtained due to clock jitter that increases clock noise. Also, noise is sometimes superimposed on the clock supplied to an analog to digital converter circuit (ADS) and the noise lowers the performance. Accordingly, the optical disc apparatus loosely regulates the bandwidth of a pulsed read signal; boosts the high-frequency components of a waveform of a driving signal of a laser diode; and synchronizes autonomously a driving clock of the ADC and a digital to analog converter circuit (DAC) with a clock of the pulsed read signal.
Claims7
An optical disc apparatus comprising:
- a laser light source;
- a light-source driving section that pulse-drives the laser light source;
- an optical system that emits the laser light generated by the laser light source onto an optical disc;
- a photodetector that receives the laser light reflected from the optical disc;
- a means for converting output of the photodetector to an electric, pulsed read signal;
- a means for controlling harmonic amplitudes of the pulsed read signal;
- and
- a means for converting the harmonic amplitude controlled pulsed read signal to a temporally continuous read signal, the conversion means operating synchronously with pulses of the harmonic amplitude controlled pulsed read signal.
A signal conversion module comprising:
- a photodetector;
- a means for converting output of the photodetector that has received a pulsed-laser-light signal to an electric, pulsed read signal;
- a means for controlling harmonic amplitudes of the pulsed read signal;
- a means for converting the harmonic amplitude controlled pulsed read signal to a time discrete signal, the conversion means operating synchronously with pulses of the harmonic amplitude controlled pulsed read signal;
- a means for converting the read signal that has been converted to the time discrete signal to a continuous signal;
- and
- a means for outputting the time discrete signal.
Dependencies are inferred from the claim text.