System for recording digital information in a pulse-length modulation format

Claim 3

A method as defined in claim 1, wherein the code blocks formed in the step of grouping each include the same number of binary bits.

Claim 4

In a system for recording digital information on a record medium in the form of a succession of spaced marks, the lengths of the successive marks being modulated in discrete system in accordance with a succession of corresponding binary code blocks, an improvement comprising means for modulating the lengths of the spaces between the successive marks, in accordance with alternate blocks of the succession of binary code blocks, whereby each of the successive ma.rks and spaces has a length representative of a separate code block and the digital information is recorded on the record medium with an increased efficiency.

Claim 5

In a system for recording digital information on a record medium in the form of a succession of spaced marks, the lengths of the successive marks being modulated in discrete system in accordance with a succession of corresponding binary code blocks, an improvement comprising means for modulating the lengths of the spaces between the successive marks, in accordance with alternate blocks of the succession of binary code blocks, whereby each of the successive ma.rks and spaces has a length representative of a separate code block and the digital information is recorded on the record medium with an increased efficiency.

Claim 6

Playback apparatus for recovering digital information stored on a record medium, the information being stored in a succession of spaced marks, each mark and each space between successive marks having a discretely-variable length representative of a separate multi-bit binary code block, the apparatus comprising means for scanning the record medium to produce a playback signal that varies in accordance with the stored,pattern of spaced marks; and detection means responsive to the playback signal for detecting the lengths of the successive marks and spaces and for providing an output signal representative of the particular code block to which each corresponds.

Claim 7

Playback apparatus for recovering digital information stored on a record medium, the information being stored in a succession of spaced marks, each mark and each space between successive marks having a discretely-variable length representative of a separate multi-bit binary code block, the apparatus comprising means for scanning the record medium to produce a playback signal that varies in accordance with the stored,pattern of spaced marks; and detection means responsive to the playback signal for detecting the lengths of the successive marks and spaces and for providing an output signal representative of the particular code block to which each corresponds.

Claim 8

A disc-shaped record medium for storing digital information in a succession of substantially circular and concentric recording tracks, the digital information being derived from a succession of multi-bit binary code blocks, wherein each recording track includes a succession of alternating marks and spaces, the lengths of the successive marks and spaces being modulated in discrete steps in accordance ith separate code blocks.

Claim 9

A disc-shaped record medium for storing digital information in a succession of substantially circular and concentric recording tracks, the digital information being derived from a succession of multi-bit binary code blocks, wherein each recording track includes a succession of alternating marks and spaces, the lengths of the successive marks and spaces being modulated in discrete steps in accordance ith separate code blocks.

Claim 10

A disc-shaped record medium as defined in claim 5, wherein each code block includes four binary bits and each mark and each space between successive marks has one of sixteen possible discrete lengths, representative of the corresponding four-bit code block.

Claim 11

A disc-shaped record medium as defined in claim 5, wherein each recording track stores a prescribed amount of digital information, and when less than an entire track is required to record the information, the remainder of the track is occupied by alternating marks and spaces representative of a prescribed filter code.