Null inflection detection and pulse expand latch in an optical recording system

[54] NULL INFLECTION DETECTION AND PULSE EXPAND LATCH IN AN OPTICAL RECORDING SYSTEM

[75] Inventors: David P. Gregg, Culver City;

Kitchener C. Wilson, Santa Barbara;
Stephen K. Shu, Fountain Valley, all of
Calif.

[73] Assignee: Del Mar Avionics, Irvine, Calif.

[21] Appl. No.: 570,144

[22] Filed: Aug. 15,1990

(Under 37 CFR 1.47)

[51] Int. CI.6 G11B 7/125

[52] U.S. CI 369/116; 369/54; 369/109;

369/58; 356/237

[58] Field of Search 369/116, 54, 58,

369/32, 112, 272, 277, 109; 356/237

[56] References Cited

U.S. PATENT DOCUMENTS

4,197,011 4/1980 Hudson 356/237

4,352,564 10/1982 Roach 356/237

4,412,743 1/1983 Eberly 369/58

4,464,050 8/1984 Kato 356/237

4,505,585 3/1985 Yushikawa 369/58

4,508,450 4/1985 Oshina 369/58

4,541,716 9/1985 Crooks et al 356/237

4,611,318 9/1986 Winslow 369/54

4,648,085 3/1987 Shimonou 369/54

4,693,608 9/1987 Kitaqawa 356/237

4,794,264 12/1988 Quackenbos et al 356/237

4,794,265 12/1988 Quackenbos 356/237

4,832,487 5/1989 Mikuriyaetal 369/53

4,908,815 3/1990 Gregg et al 369/116

4,931,336 6/1990 Haneda 369/272

5,218,591 6/1993 Shimamoto et al 369/116

5,255,007 10/1993 Bakx 369/116

Primary Examiner—Georgia Y. Epps
Assistant Examiner—Kim-Kwok Chu
Attorney, Agent, or Firm—W. D. English; J. D. Liembach

[57] ABSTRACT

A novel method and apparatus utilizing conventional photoreactive and reflective layers of a recording medium for optically recording and reading both digital and variable length, analog pulses of data, in an exacting manner to eliminate excess energy absorption by the medium and for reducing latent recording errors due to defects in the recording medium as well as due to the recording process itself. With this precise recording and reading technique, analog variable-length pulse recording, with its inherent wide bandwidth, as well as coded digital pulse recording, with its inherent narrow bandwidth, can be accommodated. The system monitors the optical transmissivity and reflectivity of the recording medium during the recording process in real time to accurately determine initial and terminal inflection points denoting inception and end of a recorded pulse in an exacting manner and to pinpoint and make allowances for recording defects which may yet yield errors on playback. A residual error reduction technique complements the variable pulse recording process by detecting and temporarily storing data and respective address at which data could not be accurately recorded due to chemical or physical anomalies in the recording medium.

22 Claims, 16 Drawing Sheets