JP2620484C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for storing digital information, and more particularly, to a video disk for storing digital information in a pulse width modulation format. -Regarding the system. 2. Description of the Related Art Video disk systems have become widely used for storing digital information with high recording efficiency. Information is typically recorded on a disk as a series of spaced marks arranged in a plurality of substantially circular and concentric recording tracks, such as a spiral pattern. One particularly effective system is a pulsed system in which each successively spaced mark on the disk represents a multi-bit code block and can be independently variable in length. Digital information has been recorded in a width modulation format. In such conventional systems, the space between successive marks, or the spacing between the beginnings of successive marks, is usually kept constant. That is, it will be understood that the length of the space could not be varied independently. [0003] Video discs can include a glass substrate with a thin metallic recording layer over the disc, and devices for recording digital information on the disc require that the disc be rotated at a uniform speed. Focus the writing light beam on the disc with the intensity of the light beam modulated according to the digital information to be recorded. When the light intensity exceeds a predetermined threshold, non-reflective pits or marks are formed in the recording layer, while
When the intensity does not exceed the threshold, the recording layer is not affected. Thus, the length of successively spaced marks corresponds to the duration during which the intensity of the focused beam exceeds this threshold. [0004] The recorded digital information is read from a replica of the recorded optical disc with a read light beam having a uniform intensity to generate a reflected beam having an intensity modulated by the recording pattern of the spaced marks. Reproduced by scanning. The intensity of the reflected beam is measured over the predetermined level to determine the length of the corresponding mark, and thus the particular binary code block that it represents. [0005] Although this conventional pulse width modulation technique has proven to be effective for recording digital information at relatively high recording efficiencies, it has been shown that digital efficiencies have been improved at higher efficiencies. A system for recording information is desired. SUMMARY OF THE INVENTION The present invention is embodied in a system for recording and reproducing digital information on a recording medium. On this recording medium, information is recorded in a series of spaced apart marks which can vary independently. The length of each mark represents a discrete one of a contiguous multi-bit binary code block. In accordance with the present invention, the spacing or space between successive marks also has an independently variable length that represents a discrete block in a series of code blocks. Thereby, digital information is recorded on the recording medium with higher recording efficiency. More specifically, the present invention has particular application to video disc systems in which the video signal is recorded on a disc-shaped recording body of substantially circular and concentric continuous record tracks. ing. The recording device first functions to digitize the video signal and compress the digitized signal using known data compression techniques. The digitized signal is arranged in a sequence of code blocks of the same or mixed length, and a binary modulated signal is formed having state transitions determined according to successive code blocks. In a preferred embodiment,
Each code block contains 4 binary bits and the continuous state of the modulated signal has 16 possible independent durations. [0008] The modulated signal is coupled to a light intensity modulator, which alternates between intensities greater than and less than a predetermined threshold for an individual duration corresponding to a succession of multi-bit code blocks. Modulates the intensity of the write beam in a simple manner. The intensity-modulated beam is focused on the recording medium in a defined pattern to form corresponding microscopic pits or marks when the recording medium is rotated at a defined speed. The recording is then used to make a replica of the video disc using conventional techniques. The recorded digital information is reproduced from a disk replica by scanning successive tracks with a reading light beam having a substantially uniform intensity. this is,
The reflected (or transmitted) beam has an intensity modulated by the recording pattern, which is alternating marks and spaces. The playback device measures the duration of successive marks and spaces and determines the particular code block that each displays. After decompressing the sequence of detected code blocks, the original analog video signal can be reproduced. [0010] In a preferred embodiment, each successive recording track is used to record an individual video frame. However, since this particular pulse width modulation format results in a variable length mark and space recording pattern, the track length required to record each video frame is typically shorter than the entire track. . When this occurs, the remaining tracks are occupied by alternating fill and fill marks and spaces. FIG. 1 shows a recording apparatus for recording a digitized video signal on a disk-shaped record 11. The device comprises a writing laser 13 for generating a writing light beam 15 having a substantially uniform intensity, and an intensity modulator 17 for modulating the intensity of the beam according to a digitized modulation signal to be recorded.
Contains. The apparatus further includes a radially movable objective lens (not shown) for focusing the intensity-modulated beam onto the record, and rotating the record at a defined uniform speed (eg, 1800 rpm). And a spindle motor 19. Thus, the focused beam forms a substantially circular and concentric recording track in the recording medium. The recording medium 11 comprises a glass substrate with a metallic recording layer covering it, and the focused beam forms microscopic pits in the recording layer whenever its intensity exceeds a predetermined threshold. . The intensity is modulated alternately above and below this threshold according to the digital modulation signal to be recorded, so that a corresponding series of spaced pits or marks is formed in the record. In accordance with the present invention, a special pulse width modulation format is provided in which both successive marks and spaces between successive marks have independently variable lengths representing successive multi-bit binary code blocks. It is recorded on the recording body 11. As a result, digital information is recorded on the recording medium with improved recording efficiency. More specifically, the recording apparatus of FIG. 1 samples the baseband video signal on line 23 and converts the analog / digital signal to a corresponding digital signal.
The digital converter 21 is included. This digital signal is coupled via line 25 to a formatter 27 for removal of vertical and horizontal synchronization signals and compression of the digital information to format the compressed data into a continuous 4-bit code block. . These successive code blocks are passed on line 29 to the appropriate storage buffer 31.
The buffer 31 stores the mark (MARK) pulse width modulator 35 and the space (SPA).
CE) Output the blocks one by one to the pulse width modulator 37 via line 33. The two pulse width modulators operate alternately to generate output pulses having independently variable durations in response to particular code blocks applied to their respective input terminals. Since the blocks are input at a substantially uniform rate, but output at a variable rate determined by the specific information contained in the code block, buffer 31 stores a predetermined number of 4-bit codes. -It must have sufficient storage capacity to store blocks. The following table shows one relationship between the 16 possible 4-bit code blocks and the duration of the corresponding pulse output by the two pulse width modulators 35 and 37. is there. Code / Hexadecimal value Length of mark (or block space) 0000 0 1.0L 0001 1 1.1L 0010 2 1.2L 0011 3 1.3L 0100 4 1.4L 0101 5 1.5L 0110 6 1.6L 0111 7 1.7L 1000 8 1.8 L 1001 9 1.9 L 1010 A 2.0 L 1011 B 2.1 L 1100 C 2.2 L 1101 D 2.3 L 1110 E 2.4 L 1111 F 2.5 L Possible pulse lengths are minimum length 1.0 L and maximum It changes in uniform steps between 2.5L in length. In other words, the length of each mark or each space is the total length {0.1L, 0.2 L,... 2.5L}, each length {1.0L, excluding each length {0.1L, 0.2L,... It is appropriately selected from 1.1L, ... 2.5L｝. It will be readily understood by those skilled in the art of this type of optical disc system that the above-mentioned allowable reproduction frequency is determined in relation to the spot diameter of the laser beam. 16
Another relationship between the two code blocks and the duration of the corresponding pulse is Jack H., entitled "Video Player / Recorder with Nonlinear Mark Length Modulation". U.S. Patent Application No. 974,183, filed under the name of Jack H. Bailey
Given in the issue. The recording device of FIG. 1 further includes a modulation coupled to intensity modulator 17 via line 41 according to successive pulse width modulation pulses received via lines 43 and 45 from MARK and SPACE modulators 35 and 37, respectively. It includes a combiner 39 for generating a signal. The combiner also provides MARK and LINE signals by providing an ENABLE signal via lines 47 and 49, respectively, to initiate operation of each modulator immediately after the previous output pulse from one modulator has paused.
Controls the timing of the SPACE modulator. The modulated signal output by the combiner on line 41 is M
Whenever the ARK modulator 35 outputs a pulse, it is in the logic "1" state and
Whenever modulator 37 outputs a pulse, it is in a logic "0" state. That is, an alternating desired pattern of marks and spaces representing successive 4-bit code blocks is formed on the recording medium 11. In the preferred embodiment, each successive recording track in recording 11 records digital information for a single video frame. As shown in FIG. 3, each track includes N sectors and each sector includes a head portion, a data portion, and a variable length filling portion. Since a fixed number of data is included in each data portion but each mark and space is of variable length, the overall length of the data portion is therefore of variable length. Thus, a filling portion is usually required. In the preferred embodiment, the fill code comprises a special sequence of marks and spaces that can be used by the corrector to reproduce the recorded information. Both the start and fill portions of each sector are generated by the formatter 27 (FIG. 1), which provides a data representation of the current frame number and sector number and the location of the particular location in the current sector being recorded. Includes a register for storing the data indication. FIG. 3 shows synchronization codes, sector address codes, and data properties (eg, video,
2 shows a head portion of each sector including a confirmation code indicating voice and the like, a correct / complementary code, and a spare portion allowing expansion of all preceding codes. Positive / complementary codes are used as a special measure to minimize the length of the data in each sector. As already explained, each sector contains a certain amount of data but is of variable length according to the particular code block being recorded. If the length of the track required to record a particular sector of data exceeds a predetermined average, the formatter 27 (
As determined by FIG. 1), the formatter outputs the complement of each code block instead of the record, and modifies the positive / complement code in the corresponding head part. In this way, the maximum track length needed to store data in any sector will all correspond to the average length, i.e. the mark and space record corresponding to code block 0111 or 1000. I do. FIG. 3 also shows the format of the data portion of each sector. It can be seen that the data includes M consecutive sections, each section preceded by a special supermark for synchronization and restart. In the preferred embodiment, each section corresponds to an 8 × 8 matrix extracted from a section of a video frame. FIG. 2 shows an apparatus for reproducing and playing the video disk replica 51 of the recorded body 11 of FIG. The apparatus includes a reading laser 53 for generating a reading light beam 55 having a substantially uniform intensity. The beam is focused as a beam spot on the disk 51 by a radially movable lens (not shown) when the disk is rotated at a uniform speed by the spindle motor 57. This results in a reflected beam 59 that is intensity modulated according to the pattern of the marks recorded on the disk. The device then detects the modulated beam and
-Measure the length of consecutive pulse widths modulated with marks and spaces to determine a bit code block. Thereafter, the original baseband video signal is reproduced. More specifically, the reproducing apparatus of FIG. 2 includes a detector 61 for detecting the modulated intensity of the reflected beam 59 and generates a corresponding electric signal. This signal is connected via line 63 to a MARK pulse width demodulator 65 and a SPACE pulse width demodulator 67,
They measure the length of successive marks and spaces, respectively, and determine the particular code block they represent. Each demodulator is a linear ramp generator, started and terminated by the detected end of each mark (or space), and for converting the peak value of the ramp into a corresponding 4-bit code block. Analog-to-digital converter. This device is further equipped with MARK and
Includes a decoder 69 for interleaving successive 4-bit code blocks provided on lines 71 and 73 from SPACE demodulators 65 and 67. The sequence of code blocks is coupled via line 75 from decoder 69 to a buffer and deformatter unit 77, which decompresses the data using conventional techniques (de-com
press) to convert the data and substantially return to the original digital format. In addition, the deformatter unit 77 inserts normal digitized vertical and horizontal sync signals into the decompressed video data. Next, the deformatter device 7
7 generates a real time digital video signal for coupling to a DA (Digital / Analog) converter 81 via line 79, the DA converter providing the original analog signal for output on line 83.・ Reproduce the baseband video signal. While the information is output from device 77 in a substantially real-time manner, a predetermined sequence of successive input code blocks received from decoder 69 at a variable rate determined by the particular information contained in the code blocks. In order to store the allocated portion, the buffer and deformatter unit 77 must include a sufficiently large memory capacity. From the above description, it can be seen that the present invention provides an improved system for recording and reproducing digital information on a disk-like recording. The information consists of multiple bits
It is stored in a series of spaced marks with both the length of the successive marks and the space between the successive marks, which are independently variable in length according to the sequence of code blocks. Digital information is thereby stored with improved recording efficiency. Although the present invention has been described with reference to preferred embodiments, it will be appreciated that the invention can be applied to audio signals as well as video signals without departing from the spirit of the invention. As is apparent from the above description, according to the present invention, in addition to the fact that the recording efficiency can be improved as compared with the conventional example in which only the mark is used, the recorded alternating information can be improved. The original code block can be decoded without error directly from the length of the mark and the space. In addition, since the length of each mark and space is given a run length limited rule in consideration of an expected reproduction system, the recorded mark and space can be reproduced faithfully. Furthermore, since the recording format has been devised in various ways, it is easy to identify the green information. As a result, the present invention provides a system for recording digital information in a format that is highly efficient and can be easily reproduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a reader for recording a digitized video signal on a video disk in a special pulse width modulation format according to the present invention. FIG. 2 is a block diagram of a reproducing apparatus for reproducing a digitized video signal stored on a video disk in a special pulse width modulation format according to the present invention. FIG. 3 is a schematic diagram illustrating a format of data on a video disk. FIG. 4 is a chart showing the prescribed length for consecutive marks (and spaces) corresponding to each of a plurality of possible 4-bit code blocks being recorded. [Description of Signs] 11 ... Disc-shaped record 13 ... Writing laser 15 ... Writing light beam 17 ... Intensity modulator 19 ... Spindle motor 21 ... Analog / digital converter 27 ... Formatter 31 ... Buffer 37 ... Pulse width modulator 39 ... Combiner.

Claims (1)

Claims: 1. A data information input means for inputting data information to be recorded arranged in units of a prescribed number of bits, and said input data information is formatted according to a predetermined rule. Recorded information generating means for generating recorded information arranged in units of a prescribed number of bits; buffer means for temporarily storing the generated recorded information; and recorded information sequentially taken out from the buffer means. Information is recorded using a run length limited code, where the length of the mark and space are both varied in uniform steps between a predetermined maximum and minimum length. A recording signal generating means for converting the recording signal into a signal; a laser beam as a writing source being intensity-modulated by the recording signal to generate a writing beam; By irradiating a spot on the photosensitive surface of the rotating recording disk, an optical recording means for performing a substantially circular and concentric track-like recording of alternating marks and spaces corresponding to the photosensitive surface, the recording device comprising: The recorded information generating means may transmit a predetermined electronic signal to the input data information.
No. After addition of processing, which together with the addition of division synchronization information to each divided for each predetermined amount, added to the frame synchronization information and frame address information in each frame consisting of defining the number of segments, further, each frame A recording apparatus, wherein recording information is generated by adding special information for specifying a property of a common electronic signal processing process regarding data information included in a frame for each frame. 2. The recording apparatus according to claim 1, wherein the special information is information for specifying that data information stored in the frame area is at least audible information or video information. . 3. The recording apparatus according to claim 1, wherein the special information is information for specifying whether or not expansion of data information stored in the frame area is permitted. 4. The recording apparatus according to claim 1, wherein the special information is information for specifying whether or not complement conversion of data information stored in the frame area is permitted. 5. The recording apparatus according to claim 1, wherein the processing is a data compression processing. 6. A run-length-limited track by scanning a substantially circular and concentric track on a recording medium with a laser beam spot and photoelectrically converting reflected light thereof.
Recording signal detecting means for detecting a recording signal comprising a code, and a recording signal comprising the detected run-length limited code, the length of a mark and a space are both predetermined maximum length and minimum length. Original recording information decoding means for converting to original recording information by decoding based on a predetermined regularity that the original recording information is changed so as to be changed in uniform steps, Data information extracting means for extracting one frame of data information in units of division from information based on predetermined section synchronization information and frame synchronization information; and A data information processing means for performing a processing specified by the special information. 7. The reproducing apparatus according to claim 6, wherein the processing is digital / analog conversion processing unique to each of the video information and the audible information. 8. The reproducing apparatus according to claim 6, wherein the processing is a data decompression on the assumption that the data information is compressed. 9. The reproducing apparatus according to claim 6, wherein the processing is a complement conversion of the data information.