Dynamic information storage or retrieval – Storage medium structure – Optical track structure
Reexamination Certificate
1993-09-13
2001-03-06
Young, W. R. (Department: 2753)
Dynamic information storage or retrieval
Storage medium structure
Optical track structure
C369S059160, C369S275400, C369S047360
Reexamination Certificate
active
06198717
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to systems for storing digital information, and, more particularly, to video disc systems for storing digital information in a pulse-length modulation format.
Video disc systems are becoming widely used for storing digital information with a high recording efficiency. The information is ordinarily recorded on the disc as a succession of spaced marks arranged in a plurality of substantially circular and concentric recording tracks, for example, a spiral pattern. One particularly efficient system has recorded the digital information in a pulse-length modulation format, in which each of the successive spaced marks has a discretely-variable length representative of a separate, multi-bit code block. The spacing between successive marks, or alternatively the spacing between the beginning edges of successive marks, is ordinarily maintained constant.
The video disc can include a glass substrate with a thin, metallic recording layer overlaying it, and apparatus for recording the digital information on ten disc ordinarily focuses a writing beam of light onto the disc, as the disc is rotated at a uniform rate, with the intensity of the beam being modulated in accordance with the digital information to be recorded. When the intensity exceeds a predetermined threshold, a non-reflective pit or mark is formed in the recording layer, whereas when the intensity does not exceed the threshold, the recording layer is not affected. Thus, the lengths of the successive, spaced marks correspond to the time duration the intensity of the focused beam exceeds this threshold.
The recorded digital information is recovered from replicas of the recorded video disc by scanning it with a reading beam of light having a uniform intensity, to produce a reflected beam having an intensity modulated by the recorded pattern of spaced marks. The length of time the intensity of the reflected beam exceeds a predetermined level is then measured to determine the length of the corresponding mark and thus the particular binary code block it represents.
Although this prior pulse-length modulation technique has proven effective in recording digital information with a relatively high recording efficiency, there is still a need for a system for recording digital information with an even higher efficiency. The present invention fulfills this need.
SUMMARY OF THE INVENTION
The present invention is embodied in a system for recording and playing back digital information on a record medium, in which the information is stored in a succession of spaced marks of discretely-variable lengths. The length of each mark is representative of a separate one of a succession of multi-bit binary code blocks. In accordance with the invention, the spaces between successive marks also have discretely-variable lengths representative of separate blocks in the succession of code blocks. Digital information is thereby recorded on the record medium with a yet higher recording efficiency.
More particularly, the present invention has particular utility in a video disc system in which a video signal is recorded on a disc-shaped record in a succession of substantially circular and concentric recording tracks. The recording apparatus functions initially to digitize the video signal and to compress the digitized signal, using known data compression techniques. The digitized signal is then arranged in a succession of code blocks of the same or mixed lengths, and a binary modulation signal is formed having transitions in state determined in accordance with the successive code blocks. In the preferred embodiment, each code block includes four binary bits, and the successive states of the modulation signal have sixteen possible discrete durations.
The modulation signal is coupled to a light intensity modulator, which modulates the intensity of a writing beam such that the intensity is alternately greater than and less than a predetermined threshold for time durations corresponding to the succession of multi-bit code blocks. The intensity-modulated beam is focused onto the record, as the record is rotated at a prescribed rate, to form corresponding microscopic pits or marks in a prescribed pattern. Using conventional techniques, the record can then be used to produce video disc replicas.
The recorded digital information is played back from disc replicas by scanning the successive tracks with a reading beam of light having a substantially uniform intensity. This produces a reflected (or transmitted) beam having an intensity modulated by the recorded pattern of alternating marks and spaces. The playback apparatus measures the time durations of the successive marks and spaces and determines the particular code blocks each represents. After de-compressing the succession of detected code blocks, the original analog video signal can be re-created.
In the preferred embodiment, each of the successive recording tracks is used to record a separate video frame. Since the special pulse-length modulation format results in a recorded pattern of marks and spaces having a variable length, however, it is usually the case that less than an entire track is required to record each video frame. When this occurs, the remainder of the track is occupied by alternating marks and spaces representative of a prescribed filler code.
Other aspects and advantages of the present invention will become apparent from the following description of the preferred embodiment, taken in conjunction with the accompanying drawings, which disclose, by way of example, the principles of the invention.
REFERENCES:
patent: 563148 (1896-06-01), Essick
patent: 1364078 (1921-01-01), Crehore
patent: 2887674 (1959-05-01), Greene
patent: 3226685 (1965-12-01), Potter et al.
patent: 3281806 (1966-10-01), Lawrence
patent: 3414894 (1968-12-01), Jacoby
patent: 3587090 (1971-06-01), Labeyrie
patent: 3624637 (1971-11-01), Irwin
patent: 3639899 (1972-02-01), Franaszek
patent: 3701846 (1972-10-01), Zenzefilis
patent: 3996613 (1976-12-01), Manning et al.
patent: 4020282 (1977-04-01), Halpern
patent: 4022986 (1977-05-01), Teer
patent: 4041530 (1977-08-01), Kramer et al.
patent: 4094013 (1978-06-01), Hill
patent: 4161753 (1979-07-01), Bailey et al.
patent: 4210931 (1980-07-01), Bailey et al.
patent: 4222072 (1980-09-01), Bailey et al.
patent: 4238843 (1980-12-01), Carasso et al.
patent: 4349901 (1982-09-01), Howe
patent: 4371894 (1983-02-01), Camras
patent: 4491940 (1985-01-01), Tinet
patent: 4500484 (1985-02-01), Gregg
patent: 5003526 (1991-03-01), Bailey
patent: 346921 (1978-12-01), None
patent: 2343017 (1973-08-01), None
patent: 644432 (1950-10-01), None
patent: 1382515 (1975-02-01), None
patent: 1489774 (1977-10-01), None
patent: 1570799 (1980-07-01), None
patent: 50-62563 (1975-05-01), None
patent: 52-128024 (1977-10-01), None
patent: 54-80726 (1979-06-01), None
Patel, A.M.; Charge-Constrained Byte-Oriented (0,3) Code; IBM Technical Disclosure Bulletin; vol. 19, No. 7, Dec. 1976, pp. 2715-2717.
Sony Es Review 1979, vol., 34 (Annex 1), English translation (Annex 1A).
DOI, et al. “A Long Play Digital Audio Disc System”, Sony Audio Technology Ctr., Tokyo, Japan, Presented in Brussels, Belgium 1979 (Annex 2).
“Development of PCM Audio Disc System for Long Play of Two and Half Hours on One Side”, Showa 53, Oct. 5th, Sony Corporation Press Release (Annex 3 and 3A), Date not available.
Annex 4: Japanese newspaper, Oct. 6, 1978.
Annex 5: Japanese newspaper, Oct. 6, 1978.
Annex 6: extracted copy of “Stero Technic” of Japanese Magazine, Dec. 1978.
Annex 7: “PCM Audio Disc System”, published on Electronics of Japanese magazine, p. 1219, Dec. 1978.
Annex 8: DAD-1X, Sony brochure, Date not available.
Annex 9: extracted copy of Billboard, Nov. 18, 1978.
Annex 10: Sony Es Review, vol. 34, 1979.
Annex 11:English translation of Japanese article “PCM Audio Disc (Record) Player”, on Television Society, pp. 1-21.
Annex 12: “A system of Optical Digital Audio Disc”.
Ogawa et al., Sony Technical Report of IECE, #EA7-8-27 (Jul. 1978).
Sato et al., “Pulse Interval and Width Modulati
Discovision Associates
Masaki Keiji
Wenskay Donald
Wong Steve A.
Young W. R.
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