JP2610764C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium on which digital information is recorded at a high density, and more specifically, an optical disc on which pulse width modulation type digital information is recorded. Related to video discs. 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. An object of the present invention is to provide a recording medium that satisfies such a demand and records digital information in a format that can be easily reproduced. 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 the preferred embodiment, each code block contains four binary bits and the continuous state of the modulated signal is one.
It has six possible individual 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. . [0016] The possible pulse lengths vary in uniform steps between a minimum length of 1.0 L and a maximum length of 2.5 L. That is, the length of each mark or each space is
From the total length {0.1L, 0.2L,... 2.5L} obtained by dividing the maximum length {2.5L} determined in consideration of the predetermined lower limit of the allowable reproduction frequency into 25 equal parts, Appropriate from the remaining lengths {1.0L, 1.1L,... 2.5L} excluding the lengths {0.1L, 0.2L,... 0.9L} corresponding to the frequency band exceeding the upper limit of the allowable reproduction frequency Selected. Regarding that the above-mentioned reproduction allowable frequency is determined in relation to the spot diameter of the laser beam,
Those skilled in the art of this type of optical disk system will readily understand. 1
Another relationship between the six code blocks and the duration of the corresponding pulse is a jack entitled "Video Playback / Recorder with Nonlinear Mark Length Modulation".
H. U.S. Patent Application No. 974,1 filed under the name of Jack H. Bailey
Given in Issue 83. The recording device of FIG. 1 further comprises a line 4 from the MARK and SPACE modulators 35 and 37, respectively.
It includes a combiner 39 for generating a modulated signal coupled to the intensity modulator 17 via line 41 according to successive pulse width modulated pulses received via 3 and 45. The combiner also provides M ENABLE signals via lines 47 and 49, respectively, to initiate operation of each modulator immediately after the previous output pulse from one modulator has paused.
Controls timing of ARK and SPACE modulators. The modulated signal output by the combiner on line 41 is in a logic "1" state whenever the MARK modulator 35 outputs a pulse and is in a logic "0" state whenever the SPACE modulator 37 outputs a pulse. .
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 a given sector is all the average length, i.e., the record of marks and spaces 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
SPACE Includes a decoder 69 for interleaving successive 4-bit code blocks provided on lines 71 and 73 from 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.
ress) 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 being able to improve the recording efficiency as compared with the conventional example in which information is recorded using only marks, the information is recorded. The original code block can be decoded without error directly from the length of the alternate marks and spaces. 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. Further, since various modifications are made to the recording format, identification of recording information and the like becomes easy. as a result,
The present invention provides a recording medium on which digital information is recorded in a format that can be easily reproduced with high efficiency.

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: disk-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 recording medium on which digital information is recorded during a sequence of recording tracks, wherein the digital information comprises a sequence of original binary bits that is digital information to be recorded. Obtained by transforming a sequence of coded signals into a sequence of coded signals, said transform performing only a first coding operation to encode each original portion of the sequence of binary bits into a coded portion. Performed by encoding each part of the sequence of binary bits using and without using any operation of processing the encoded part following the first encoding operation, The coded part of is the final code representing each original part of the sequence of binary bits, and The information is formed on the recording track of the recording medium as a series of alternating marks and spaces so that the marks and spaces indicate the corresponding part of the continuation of the coded signal. The length of successive marks and spaces formed is modulated to an individual length according to the sequence of the coded signals, between a minimum length and a maximum length that is at least twice that length; The recording track of the recording medium is divided into unit sections for recording a specified amount of digital information, and when the entire unit section is not required for recording, the remaining portion of the unit section includes a specified section. A recording medium, wherein alternating marks and spaces are formed. 2. The digital information to be recorded includes: a first step of sampling an analog signal to be recorded at a specified frequency to generate a sequence of sampled data; and defining the sequence of the sampled data. 2. The recording medium according to claim 1, wherein the recording medium is provided through: a second step of quantizing the number of binary bits to generate a sequence of quantized data. 3. A recording medium on which digital information is recorded during a sequence of recording tracks, wherein the digital information is a signal encoded with a sequence of original binary bits, which is the digital information to be recorded. Transforming to a continuous, said transform using only a first coding operation to encode each original part of said sequence of binary bits into a coded part, and The first encoding operation is performed by encoding each portion of the sequence of binary bits without using any operation of processing the encoded portion, and the respective encoded The part is the final code representing each original part of the series of binary bits, and the information representing the series of coded parts is a mark. A series of alternating marks and spaces are formed on the recording track of the recording medium as a series of alternating marks and spaces, such that the continuous and the coded signal indicate a corresponding portion of the sequence of the coded signal. The length of the mark and the space is modulated between a minimum length and a maximum length that is at least twice the length according to the continuation of the coded signal, to an independent length, and the recording track of the recording medium. Is divided into unit sections for recording a specified amount of digital information, the section has a calibration area, and a specific position of the unit section specifies a type of information recorded in the unit section. A recording medium, wherein an identification code is formed. 4. The digital information to be recorded includes: a first step of sampling an analog signal to be recorded at a specified frequency to generate a sequence of sampled data; and defining the sequence of the sampled data. 4. The recording medium according to claim 3, wherein the recording medium is provided through a second step of quantizing the number of binary bits to generate a sequence of quantized data. 5. The recording medium according to claim 3, wherein the identification code can represent at least video information and audio information. 6. A recording medium on which digital information is recorded during a sequence of recording tracks, said digital information being a signal encoded from a sequence of original binary bits that is the digital information to be recorded. Transforming to a continuous, said transform using only a first coding operation to encode each original part of said sequence of binary bits into a coded part, and The first encoding operation is performed by encoding each portion of the sequence of binary bits without using any operation of processing the encoded portion, and the respective encoded The part is the final code representing each original part of the series of binary bits, and the information representing the series of coded parts is a mark. A series of alternating marks and spaces are formed on the recording track of the recording medium as a series of alternating marks and spaces, such that the continuous and the coded signal indicate a corresponding portion of the sequence of the coded signal. The length of the mark and the space is modulated between a minimum length and a maximum length that is at least twice the length according to the continuation of the coded signal, to an independent length, and the recording track of the recording medium. Is divided into unit sections for recording a predetermined amount of digital information, the section has a calibration area, and an address code for specifying the unit section is formed at a specific position of the unit section. Recording medium characterized by the above-mentioned. 7. The digital information to be recorded includes: a first step of sampling an analog symbol to be recorded at a prescribed frequency to generate a sequence of sampled data; and defining the sequence of the sampled data. 7. The recording medium according to claim 6, wherein the recording medium is provided through a second step of quantizing the number of binary bits to generate a sequence of quantized data. 8. A recording medium on which digital information is recorded during a sequence of recording tracks, said digital information being a signal encoded from a sequence of original binary bits that is the digital information to be recorded. Obtained by converting to a series, each of the series of binary bits can be represented by one and only one possible series of encoded signals, and the information representing the series of encoded parts is: , Marks and spaces are formed on the recording tracks of the recording medium as alternating mark and space continuations, so as to indicate corresponding portions of the continuation of the coded signal, and are formed on the recording tracks of the recording medium. The length of consecutive marks and spaces is between the minimum length and the maximum length, which is more than twice that length, according to the sequence of the coded signal. The recording track of the recording medium is divided into unit sections for recording a predetermined amount of digital information, and when the entire unit section is not required for recording, The recording medium according to claim 1, wherein prescribed alternate marks and spaces are formed in the remaining portion of the unit section. 9. The digital information to be recorded includes: a first step of sampling an analog signal to be recorded at a specified frequency to generate a sequence of sampled data; and defining the sequence of the sampled data. 9. The recording medium according to claim 8, wherein the recording medium is provided through a second step of quantizing with a binary number of bits to generate a sequence of quantized data. 10. A recording medium on which digital information is recorded during a sequence of recording tracks, wherein the digital information is a signal encoded with a sequence of original binary bits that is the digital information to be recorded. Obtained by converting to a series, each of the series of binary bits can be represented by one and only one possible series of encoded signals, and the information representing the series of encoded parts is: , Marks and spaces are formed on the recording tracks of the recording medium as alternating mark and space continuations, so as to indicate corresponding portions of the continuation of the coded signal, and are formed on the recording tracks of the recording medium. The length of successive marks and spaces is between the minimum length and the maximum length, which is more than twice that length, for the continuation of the coded signal. Is modulated to the length of the individual independent I, a recording track of said recording medium is divided into unit intervals for recording digital information specified amount, the section has a calibration area, said unit section A recording medium, characterized in that an identification code for specifying the type of information recorded in the unit section is formed at the specific position. 11. The digital information to be recorded includes: a first step of sampling an analog signal to be recorded at a prescribed frequency to generate a sequence of sampled data; and defining the sequence of the sampled data. The recording medium according to claim 10, wherein the recording medium is provided through a second step of quantizing with a binary number of bits to generate a sequence of quantized data. 12. The recording medium according to claim 10, wherein said identification code can represent at least video information and audio information. 13. A recording medium on which digital information is recorded during a sequence of recording tracks, said digital information being a signal encoded from a sequence of original binary bits that is the digital information to be recorded. Obtained by converting to a series, each of the series of binary bits can be represented by one and only one possible series of encoded signals, and the information representing the series of encoded parts is , Marks and spaces are formed on the recording tracks of the recording medium as alternating continuations of marks and spaces so as to indicate the corresponding portions of the continuation of the coded signal, and are formed on the recording tracks of the recording medium. The length of successive marks and spaces is between the minimum length and the maximum length, which is more than twice that length, in the sequence of the coded signal. Is modulated to the length of the individual independent I, a recording track of said recording medium is divided into unit intervals for recording digital information specified amount, the section has a calibration area, said unit section A recording medium, wherein an address code for specifying the unit section is formed at the specified position. 14. The digital information to be recorded includes: a first step of sampling an analog signal to be recorded at a prescribed frequency to generate a sequence of sampled data; and defining the sequence of the sampled data. 14. The recording medium according to claim 13, wherein the recording medium is provided through a second step of quantizing the number of binary bits to generate a sequence of quantized data.