Eastman-Kodak Company

Jeffrey T Klaus

Clarke K Eastman

Roger A Hajjar

Michael E Meichle

Steven C Dohmeier

A method for adjusting the timing for sampling a reflected write signal is disclosed. The method comprises determining a reference timing event, and sampling the reflected write signal at first and second sampling times to produce first and second sampled signals, the first sampling time occurring after a first variable time delay following the reference timing event and the second sampling time occurring after a first fixed time delay following the first sampling time. The method further comprises comparing the magnitudes of the first and second sampled signals, and adjusting the first variable time delay in response to the comparison of the magnitudes of the first and second sampled signals so that the magnitudes of the first and second sampled signals are substantially equal.

Sampling timing for a reflected write signal

An apparatus and method for use in an optical recording system in which an incident beam records data on an optical recording medium as marks and in which a return beam reflected from the medium is detected in an optical detector to provide a reflected write signal. A number of reflected write pulses of the reflected write signal are monitored in an interference detector. The peak voltage or other suitable characteristic of a reflected pulse corresponding to a mark following a relatively short land is compared to the same characteristic of another reflected pulse corresponding to a mark following a longer land. An error signal is generated based on the comparison and provides an indication of the amount of intersymbol interference (ISI) present during recording of the marks corresponding to the first and second reflected pulses.

Intersymbol interference detection in an optical recording system using

An apparatus for use in an optical system in which information is read from a recorded wobbled groove of an optical medium by detecting first and second portions of a return beam in first and second detectors producing detected signals, respectively, the apparatus comprising: gain control circuit means coupled to the first and second detectors, respectively, and receiving the first and second detected signals therefrom; the gain control circuit means being responsive to the detected signals for producing a summation signal which is a function of the sum of the two detected signals; a first signal difference circuit coupled to the first and second detected signals for providing a difference signal; and a second signal difference circuit responsive to the difference signal and the summation signal for producing a wobbled groove information signal.

Low noise atip detection from an optical recording medium with wobbled

A level detector for detecting a voltage level of a signal, is disclosed. The level detector includes a signal comparator having a first input for receiving the signal; a first switch responsive to an output of the signal comparator to connect a first current source to an output of the detector. The first current source connected between a first voltage reference and the first switch, the detector output feeding back to a second input of the signal comparator, such that the first current source supplies current to the detector output until a voltage at the detector output is greater than the voltage level of the signal. The level detector further includes a reference pulse input for receiving a reference pulse having a predetermined time duration; a second switch responsive to the reference pulse to connect a second current source to the detector output, the second current source connected between a second voltage reference and the second switch, such that the second current source supplies current to the detector output for a period of time substantially equivalent to the predetermined reference pulse duration; and an energy storage structure connected between the detector output and a constant voltage potential of the detector, such that the output voltage of the detector varies in response to current supplied to the detector output from the first and the second current sources.

Level detector for detecting a voltage level of a signal

An optical recording system and method which provide verification of recorded data, while the data is being written onto an optical recording medium, by detecting the rate of change of a reflected write pulse. The system includes an optical source for supplying a intensity-modulated incident write signal, having at least one write pulse, to an optical recording medium. The write signal records a logic level of the data on the medium as a mark having a distinct reflectivity. An optical detector detects a reflection of the incident write signal from the medium to provide a reflected write signal which includes a reflected write pulse corresponding to the incident write pulse. The reflected write pulse has a rate of change resulting from a change in reflectivity of the optical medium as the mark is formed thereon. A mark formation effectiveness signal generator receives the reflected write signal and generates a mark formation effectiveness signal which estimates a normalized rate of change of the reflected pulse, to provide an indication of the quality of mark formation on the medium. Comparison means may be included for comparing the measured mark formation effectiveness signal with a predetermined range of acceptable rates of change in order to verify proper mark formation.

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Rochester, NY, United States of America

Jeffrey T Klaus