JPH06503197A - Media, methods and devices for information storage and retrieval - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Media, methods and devices for information storage and retrieval technical field The present invention generally relates to a medium for transmitting symbols representing digital information; Recovering from a medium the symbols it represents and the digital information represented by such symbols. Concerning confirmation. The invention has many uses, but here, among other things, the symbol A tape that arranges symbols in thinly wound, concentric, parallel, or [a-line] tracks. restored from and transmitted by a tape- and disk-based storage medium. , which describes the preferred embodiment.

Background technology With the expansion of applications for digital computers and digital processing, storage media To discover methods and devices for searching digital information more efficiently. interest has increased. To make information storage retrieval more efficient, information storage technologies that increase capacity, reduce information access time, and reduce equipment and media costs. includes progress in

Commonly used storage techniques include tape- and disk-based storage media. It utilizes magnetic and laser light technology to store and retrieve digital information. De Digital information is usually arranged on a medium in linear columns or "tracks" of binary symbols. lined up. For example, magnetic tape stores digital information along the length of the tape. , or diagonally across the width of the tape. can be stored as magnetic flux changes within the further tracks. magnetic disc discs typically arrange digital information in concentric circles around the center of the disc. It is stored as the magnetic flux change within the track. Laser optical discs play an important role, Digital information is stored in tracks that spiral toward the center of the disc. raised or surfaced against reflective areas around the disc, arranged in It is memorized as a reflective spot of either shape.

The information storage capacity of a storage medium is determined by the dimensions of the medium and the density of symbols transmitted by the medium. It is confirmed with. Symbol density is the spacing between adjacent symbols within a track and the The distance between tracks is determined. It has only one spiral track. For optical storage media, adjacent tracks are considered to mean adjacent turns of the spiral. available.

The "width" of a track is distinct from, but related to, the spacing between adjacent tracks. . That is, the width of the track is the dimension across the track that intersects the length of the track. represent.

In most applications, the track width is less than the spacing between adjacent tracks; This prevents the guard band j from being used for storing information [if the guard band j obtained in between.

Increased information storage capacity generally reduces the spacing between symbols arranged in tracks. This has been achieved by reducing the spacing between adjacent tracks. did Accordingly, a mass storage medium consists of a very large number of very large They tend to consist of narrow tracks.

By increasing the information storage capacity in this way, in many cases, information can be stored, The cost of equipment used for searching increases. This is because the large capacity of this format Storage media depend on the accuracy and accuracy of the electrical and mechanical devices used to store and retrieve information. This is because very strong requirements are placed on speed. The device records information on the media. When the memory or test is to be performed, the magnetic An optical “head” or optical “pick-up” sensor is located within a specific track width. must be moved accurately in order to position it. This means that the width of the track is The narrower the space, the more difficult it becomes.

In addition to this, increasing information storage capacity in this way often access time becomes longer. The time required to accurately position the sensor is determined by This is the distance of the track the head must move. There are many variables including the distance or number, the precision with which the sensor must be placed, and the mass of the sensor. adversely affected by a number of factors. Large number of trucks placed close together Therefore, it is difficult to achieve low seek times on high-capacity magnetic media. However, it has more tracks than that, and the track spacing is even closer. Achieving low seek times is particularly important for laser optical media that Have difficulty.

Furthermore, the laser optical pickup has a mass that is several times larger than the magnetic head. Why? Laser optical pickups typically include a laser, a lens system, one or more This is because it is composed of a photodetector and a diffraction grating. This larger mass to quickly and accurately move the pickup from one truck to another. It becomes more difficult to do so.

Unfortunately, increases in storage density do not necessarily result in equivalent increases in information storage capacity. It doesn't matter. This is because the amount of energy needed to compensate for the increased storage density , control and timing information, or "flags"; This is because space must be used.

Flags must (1) establish the relationship between time and distance across the storage medium, and (2) identify segments of digital information; and (3) establish structures that can store digital information. Contains information that specifies the Some examples of these flags include clock pulses. or timing information, track index, and track location information.

Track position information is used in closed loop head servo position control. Closed loop・ Servo position (I@ control is required.

Because, due to several factors such as vibration and thermal expansion and contraction of the medium, the track This is because the absolute position of the track can be displaced by a distance on the order of the spacing between. magnetic medium In the body, track position information is often mechanically linked to other disks. Stored on a separate disk dedicated to servo information or on a track. Blocks of symbols as "servo" information stored on one disk adjacent to each other. Memorized during lock. In the laser optical medium, closed loop servo am has , in addition to the "index" information stored within the tracks, the anti-protective bands between tracks Projection surfaces are often used.

Accurately recovering symbols in a track requires accurate timing information and Advanced technology devices provide precise timing information at the time a symbol is detected on a storage medium. It is intended to be confirmed. In order to accurately interpret symbols, through the symbol reconstruction process, The location where each symbol is stored and the value represented by each symbol can be determined accurately. is necessary.

The position of each symbol is determined by the precise time each symbol was written on the medium; This can be caused by time instability or "jitter" during both the write and read processes. It becomes difficult to accurately determine timing information. Jitter causes digital An uncertainty similar to the uncertainty caused by noise in the value represented by the symbol sex is brought about.

Jitter is caused by the "wow" and "flutter" of the tape, or changes in the rotational speed of the disk. Variations in the speed of the storage media drive, such as Out.

displacement of a "clock" or timing signal used to control the Caused by many factors. Like a video cassette tape recorder for honey garden Jitter in standard equipment is caused by irregularities in the tape surface at the tape-to-head contact, Shock waves spreading along the tape surface generated by a rotating head striking the tape surface , and caused by the tape cab's tongue servo attempting to follow the video signal. It can also be caused by additional factors, such as variations in the tape drive mechanism.

In part, we have achieved a storage medium drive mechanism that is stable enough to eliminate jitter. The cost would be too high (too much) to try, but with a reasonably stable drive mechanism, the remaining It is possible to reduce jitter to the extent that it is possible to compensate for residual jitter. This technology Several methods have been used in the field to compensate for jeddah; are either not fully effective or reduce storage capacity. be. In one method, when a transition between binary symbols is effected by compared to the inter-certainty, which is limited to several times the time. In this method, between symbols Spacing increases and information storage density decreases.

In the second method, clock pulses are stored along with the symbols stored on the medium. However, this significantly reduces information storage capacity. The reason is that the clock pattern This is because a significant amount of space is required to memorize the ruses.

In the third method, the timing information is from a voltage 1llllllll type oscillator whose frequency is adjusted to minimize the phase error at the It is generated from a phase-locked circuit (PLL) consisting of: When no transition error occurs , the oscillator uses the last learned frequency and phase until it can synchronize itself to subsequent transitions. "Inertial oscillation" occurs. This method eliminates the overhead of storing clock pulses. , but a long sequence of symbols with no transitions, i.e. with the same value It does not work well for long strings of symbols.

In the fourth method, again a PLL is used, but the symbols that can occur without transitions Stored information is encoded according to a "channel code" that constrains the length of the column. . Although the accuracy of the clock generated by PI,■, is improved, the channel code Incurs overhead costs for storing information.

Increased storage space and reduced information access times combine to deliver faster data Transmission speed is imposed on the information retrieval process. In particular, in the process of symbol restoration, symbols are Ability to recover timing information and correct symbol errors as they are detected on the body There must be. As information storage capacity increases and access times decrease , it becomes difficult to restore timing information. This is because the information to be processed as the amount of time available to perform these functions decreases. Ru.

Thus, large-capacity disks such as magnetic tapes or disks, or laser-optical disks Digital storage media consists of a large number of closely spaced, narrow tracks . Efficient retrieval of information from such storage media requires (1) controlling the position of the sensor; (2) stable drive mechanism that minimizes jitter; (3) Storage overhead for storing flags such as rack position information and clock recovery information; and (4) provide timing information to recover symbols at faster data transmission rates. A rapid symbol recovery process is needed.

Disclosure of invention The object of the present invention is that the symbols must be carried out as they are received from the storage medium. The aim is to lower the requirements placed on the symbol recovery process, which is not necessary.

Another object of the invention is to recover data timing or clock information. By reducing the overhead required to store information that is only used for The goal is to increase the net capacity of the storage medium.

Yet another object of the present invention is to provide electrical and Provide a high-capacity information storage medium that imposes low requirements on the accuracy of mechanical actuators That's true.

A further object of the invention is to place lower requirements on the speed stability of electro-mechanical storage media drives. The objective is to provide a large-capacity information storage medium.

In its broadest aspect, the present invention has the ability to represent digital information on a storage medium. can be transmitted in two or more dimensions, or can be transmitted in two or more dimensions from a storage medium. Any distinguishable notation that has the ability to be reconstructed into a representation of one or more dimensions. It is contemplated that all storage media capable of transmitting signals may be used. This invention can be applied to higher dimensions. In the following, inter alia, two-dimensional notation is used in this specification. Become familiar with storage media called storage media.

Examples of two-dimensional storage media include magnetic storage media such as tape, paper, and disks; and optical storage media such as paper, discs, and film.

In accordance with the teachings of the present invention, an apparatus for recovering digital symbols from a storage medium is provided. A signal representing a symbol is received by the receiver, and the received signal is sampled and an image of the signal is obtained. An image representation is derived from the sample, and from the image representation the value represented by the symbol is derived. will be restored.

Also, in accordance with the teachings of the present invention, an information storage medium has one or more tracks of symbols. with each track having two or more symbols running across the width of the track. The symbols are encoded two-dimensionally within each track.

"Two-dimensionally encoded" or "two-dimensionally encoded" as used herein with respect to symbols A term such as ``physical encoding'' refers to the information represented by a symbol that is Distinguishable properties and the relationship between one symbol and another, or one symbol with respect to another It can only be determined from the two-dimensional arrangement with some other reference on the medium. It means that you can. relating to a symbol or arrangement of symbols with respect to the medium itself No flags are required. Distinguishable characteristics unique to symbols include optical reflectance or transmittance, shape, color, size, and orientation. Distinguishable characteristics and relative locations The position or combination with a positional characteristic is referred to herein as a distinguishable positional characteristic.

The present invention provides, inter alia, that the placement or position and distinguishable characteristics of symbols are of statistical variables. This is advantageous when used with actual storage media, i.e. they are non-uniform. It is. Variations in distinguishable positional characteristics may be due to distortions in the medium itself or due to This can be caused by a lack of consistency in the application of the signal to the medium.

The number of signals representing symbols transmitted by a two-dimensional storage medium is small (also one-dimensional). minutes oversampled. Oversampling is the Nyquist Sun sampling at a rate higher than the pulling rate. favorable fruit In the example, two adjacent symbols constitute one complete period of data. sampling at a higher rate than Nyquist sampling is less accurate. means sampling at a rate higher than once per symbol. A symbol becomes a symbol Oversampling for each dimension for which the relative position and timing information is uncertain be logged. This is discussed in more detail below.

The representation of a symbol transmitted by a storage medium involves sampling the symbol in two dimensions. derived from the sample produced by and. transmitted by a storage medium This symbol representation allows us to identify distinguishable positional properties of the symbol transmitted by the storage medium. A two-dimensional image representation is constructed to convey the message.

Reconstruction - filtering in two dimensions with the properties of waves or image enhancement to create a two-dimensional image In order to improve the resolution of the representation, the two-dimensional image representation is Find the symbol and desire the digital value of the digital information represented by the symbol. can be adapted to be determined within a certain range of accuracy. carrying out the invention Although reconstructed ura waves are important for the realization of a device that and will not be discussed in detail herein.

In this specification, the digital value of digital information expressed by each symbol is This is determined by examining the distinguishable positional characteristics of the image representation. is restored from the image representation. The distinguishable characteristic has one or more reference values and be compared. That is, for example, optical properties may include light transmission or reflection1. Compare with threshold be done. The location characteristic has one or more reference values, i.e. a set of expectations, e.g. relative symbol position.

According to the present invention, the high weight of small symbols transmitted by a storage medium is The reconstruction of the array and the determination of the digital information represented by the symbols are completely electronic. Pneumatic, optical and electronic methods make this possible without the need for precise placement techniques. storage medium The symbols transmitted by the body only need to be within the sensing range of the sensing device. Not possible.

There is no requirement for close alignment between the storage medium and the sensing device, and there is no requirement for close alignment between the storage medium and the sensing device. There are no requirements for proper synchronization, clock synchronization, or tracking. timing information There is no need for the information or flag to be transmitted by a storage medium.

This is because symbol reconstruction either establishes the distance between the symbol and a known reference, or depends on determining the distance between the two symbols. accurate timing The mapping information is derived from a comparison between the determined symbol distance and the known expected distance. It will be done. This process of deriving accurate timing information is referred to herein as ``clock recovery.'' This is called the ``original'' or ``timebase correction.'' In addition to simplifying the process of symbol restoration, Therefore, the absence of clock or timing information makes the storage medium more This reduces the amount of information transmission area available for other purposes.

The invention has been described with particular reference to embodiments in which the storage medium is an optical disc. Ru. The features and teachings of the invention described below with respect to optical disc storage media are It has other formats such as tape or sheet, and can be used for photographic, stamp, magnetic/optical, phase change, dyeing. colored polymers, abla-Nve, injection molded plastics, and Optical media utilizing optical markings applied by other similar marking techniques It is directly applicable to the body j2.

In a preferred embodiment for optical discs, the symbols representing digital information are , a set of discrete (,segments) in the form of two-dimensional blocks of symbols, by disk. It is transmitted in the form of In principle, such segments can be of any convenient length or size. Something like this is fine. This information is recorded by oversampling the block two-dimensionally. A two-dimensional image representation of each block of the code is derived and represented by each symbol in the block. is read by determining the digital value that is

The basic principles of the invention provide for special alignment or does not have any strict requirements for synchronization, and does not require the information on disk to be clocked at the same time. There is also no requirement for follow-up. The image representation of the block of symbols is The determination of the digital value represented by the symbol is based on the optical properties and position of the symbol. It is a two-dimensional image representation that allows Ru.

In one embodiment relating to an optical disc, the block of symbols is rectangular in shape. belongs to. Each block contains one or more symbols to help locate the symbol. Alignment pattern or base 1 may have the above alignment pattern or reference, but alignment pattern or base 1 is required. isn't it. Using less processing power by using alignment patterns or standards It becomes possible to determine the position of the symbol.

The terms "alignment pattern" and "pattern" herein refer to means any criteria that can be used to assist in arranging and locating the symbols that It is used as if Therefore, we have changed these terms to the phrase “pattern.” They should not be construed as including any implied limitations.

If you use an aligned pattern, the lower the value when the pattern does not match itself The alignment pattern preferably has autocorrelation so that an autocorrelation value occurs. We should. A synergistic Barker code may also be used. In one embodiment, An alignment pattern is placed at each corner of each block of symbols. The process described below For simplicity, the four alignment patterns are equivalent, but in principle each They may be different from each other.

In one embodiment for optical discs, the symbol is separated by the center of the symbol. From the intersection of a radial line passing through the disc center and a concentric arc around the disc center are arranged with respect to each other in such a way that the lattice formed is determined. In the present invention, The relative arrangement of the numbers is not limited to this form. For example, the center of the symbol in such a way that the intersections of a rectangular grid with lines equally spaced are determined by , may be placed.

In one embodiment of an apparatus for retrieving digital information from magnetic tape. , symbols representing digital information are drawn across the width of the tape at right angles. It is transmitted in a series of running parallel tracks. This information determines the length of each track. The two-dimensional image representation is obtained by sampling along the is read by determining the digital value represented by the symbol.

The basic principles of the invention allow clock synchronization or tracking of information on tape. There are no strict requirements regarding this.

The image representation of a symbol determines the digital value represented by the symbol. Allows you to do things based on characteristics and location, independent of timing or flags. It is a two-dimensional image representation.

One device according to the invention uses home video, which typically has poor timing stability. -Storing digital information on conventional recording devices such as cassette tape recorders Then, digital information is retrieved from the recording device. This is because the present invention enables recording and Depends only on the bandwidth of the playback mechanism and the normal tracking accuracy of the head to the signal track. This is because it exists. This device provides the low power that is normally required in digital systems. does not require long-term stability of data or tape speed.

As noted above, the invention is susceptible to applications, media, and storage techniques other than the preferred embodiments. Applicable. For example, the present invention can be used to create optically or magnetically distinguishable marks. The information from the paper is transferred using electrostatic toner or magnetic ink. It can be used to store and retrieve information. documents, music, audio, video Storing extremely large amounts of information such as video images or digital data on paper However, it could also be easily and inexpensively read out using ordinary incoherent light.

11th day! ! Yugoj FIG. 1 illustrates a disk carrying tracks of symbol blocks in accordance with one aspect of the invention. 1 is a diagram of an optical storage medium in the form of a disk.

FIG. 2 is a more detailed diagram of the symbol block.

FIG. 3 is a functional block diagram of an apparatus incorporating one aspect of the present invention.

FIG. 4 illustrates the functionality of the video processor portion of a device incorporating one aspect of the present invention. It is a block diagram.

FIG. 5 illustrates the functionality of the image processor portion of an apparatus incorporating one aspect of the present invention. FIG.

FIG. 6 is a diagram illustrating a method used to transmit digital information according to one aspect of the invention. of a televised screen showing the area of the picture area corresponding to the part of the video signal It is a diagram.

Preferred form for carrying out the invention A. Medium Referring to Figure 1, the storage medium that transmits symbols representing digital information is optical digital. It is shown in the form of screen 2.

Digital information is stored in a number of concentric tracks centered around the center of the disk. 4 or adjacent concentric lines without departing from the scope of the invention. arranged in a single spiral track with a pitch similar to the spacing between circular tracks. can be lined up. To be more specific, Figure 1 shows an optical disc. However, one aspect of the invention is to provide two-dimensional oversizing of symbols transmitted by a medium. It is applicable to other media compatible with sampling.

A portion of FIG. 1 shows the digital information transmitted in track 4 on disk 2. A representative two-dimensional symbol array or block 6 is shown. Figure 2 shows the symbols Ro-tsuku is shown in more detail.

The optical storage medium shown in FIG. It will be seen that it consists of fewer tracks, each carrying a symbol.

Each symbol shown in this figure is represented by either a black or white rectangle.

In principle, these symbols represent zones that allow information to be stored and retrieved on a storage medium. You can use any convenient thing with distinguishable characteristics and shape, but in this figure, it is expressed as a storm. Represented as a black or white rectangle to facilitate. Regarding the uses of optical memory , the symbol is expected to be realized as an essentially circular reflective and non-reflective spot. However, this is not a requirement. For the following discussion, the medium shown in this diagram The symbols and other areas above assume that the black areas represent non-reflective areas. , assume that the white symbols and areas represent reflective areas.

With respect to these figures, block 6 of symbols transmitted in track 4 of medium 2 is shown. In a portion of FIG. 1, white bands and dotted lines are shown between adjacent tracks. this white The strips and dotted lines are only intended to draw attention to the block of symbols within the track. This is what I did. In the present invention, there is no need for special boundaries between tracks, and adjacent tracks can be Symbol blocks in a block may be adjacent to each other.

The 2'Is value represented by each type of symbol is arbitrary.

For purposes of this discussion, the value 0 will be represented by a black or non-reflective symbol, and a white or non-reflective symbol will represent the value 0. Assume that the value 1 is expressed by the morphism symbol.

The number of symbols shown in each block is not critical to the implementation of the invention However, many implementations use blocks of 50 to 100 symbols in each dimension. It is simply a matter of foreseeing that there is a situation and showing it.

The size of each symbol is inversely related to the number of symbols that can be transmitted in a given area.

The digital data rate can be reduced by symbol size when no other changes are made. and can be increased by reducing the symbol size by reducing the symbol size. The ability to accurately determine the digital information represented by is impaired. for example, Smaller symbols are more susceptible to damage to the media surface and are more susceptible to focus errors in optical sensing equipment. Easily affected by differences. Additionally, the minimum size of the symbol that can be used is Limited by diffraction effects.

The figure does not show unused areas or "guard bands" between symbol blocks. Protection Although the protection band is not essential to the practice of the invention, it can be used as discussed below. This simplifies the process of finding the exact location of each symbol block. be able to.

The diagram also shows a set of radial lines passing through the center of the disk and the symbol by the center of the symbol. It is formed from the intersection with a set of circular arcs extending along concentric circles centered on the disk center. It also shows blocks of symbols placed adjacent to each other in the way the intersection points of the grid are determined. I'm nestling. These symbols do not have to be adjacent, but can be used with each other or in other positions. Any convenient pattern for determining the symbol position relative to the base may be used. .

one or more criteria that can assist in locating the exact center of each symbol It is possible to determine.

These criteria are either external to the field or internal to the field. It may consist of one or more symbols. These standards are referred to in this specification. , [Alignment pattern ("aHgnent pattern')" is called J. Although the column pattern is not necessary for the implementation of the invention, it does allow for locating the symbol. This can significantly reduce the amount of processing required to

An alignment pattern can be placed at each of the four corners of each block of symbols. 4 not yet A complete pattern is defined for a specific application, the frequency of data transmitted by the medium, and the symbology. Operation is possible depending on the processing capacity of the restoration device. Instead of this, block of symbols Find the symbols and determine their digital values. It can be used as an aid.

If alignment patterns are used, each of the one or more alignment patterns must consist of an array of symbols with good autocorrelation properties. 7 A x7 array is used in the embodiment shown. Auto-correlation of alignment patterns The characteristic is such that low autocorrelation values occur when the pattern does not match itself. It is gender.

Synergistic 7-bit Barker code (cross-vulNpHed?-bit Barker code) (111001,02), the desired autophase relationship characteristics are satisfied. If you use more than one alignment pattern, the alignment pattern Every turn contains an array of several symbols, and every alignment pattern contains a block of symbols. Preferably placed at each corner of the lock.

In a preferred embodiment, bands of opaque symbols are aligned on the two inner edges of the pattern. The alignment pattern and the opaque band of symbols form an 8x87 ray of symbols. will be accomplished.

B. Equipment FIG. 3 is a high-level block diagram of a VTLL incorporating a preferred embodiment of the present invention. Ru. The optical sensor 100 generates a two-dimensionally encoded image transmitted by an optical storage medium. The received information is optically scanned and a video signal is generated in response to this information. B A video processor 120 controls the scanning speed of the optical sensor 100 and A digital signal forming a two-dimensional image representation is generated in response to the signal.

The image processor 140 is used to improve the resolution of two-dimensional image representations. optically encoded where a two-dimensional image representation is filtered and transmitted by an optical storage medium Digital information corresponding to the value of the information is generated.

Information processor 160 processes the retrieved digital information into Processed according to its intended use.

1. Optical sensor Optical sensor 100 detects optically distinguishable characteristics of the symbol. this optics The particular implementation of the target sensing device is not important to the implementation of the invention. Examples are medium It will vary depending on the body and use. Linear CCDs are generally relatively inexpensive and small. It is a preferred optical sensor because it is compact and has impact resistance, but in principle, other Optical sensors of the type can also be used subject to the requirements between scanning speed and resolution.

Although the source of illumination is also not critical to the realization of the invention, the source of illumination and the light sensor are The sensors shall operate together to provide two-dimensional oversampling of the surface of the optical storage medium. Must be.

For rotating optical disk media, the illumination source and optical sensor are located at the center of the disk. driven by an actuator that controls the radial position of the sensing device relative to the It is envisaged that the device will be physically attached to the lever or arm that is used. optical disk rotates, which causes the symbol transmitted on the disk to move relative to the sensing device. let Transverse direction of relative movement of the symbol to the sensor by the sensing device itself One-dimensional sampling is performed. In this specification, we refer to this sampling as horizontal This is called directional sampling. Sampling by a sensing device as the disc rotates parallel to the relative movement of the symbol to the sensor, in this specification perpendicular Sampling in a second dimension, called directional sampling, takes place.

For embodiments using CCD light sensors, the symbol may include more than one CCD element or optically scans horizontally by imaging each symbol on a pixel. bar sampled, one symbol per symbol as it moves relative to the CCD array. optically in the vertical direction by reading out the CCD array at a rate greater than once per is oversampled. This horizontal oversampling rate is is a function of symbol size, optical magnification, and CCD array vixel size. . This vertical oversampling rate is determined by the symbol size, disk rotation angle speed and the line scan speed of the CCD.

In the present invention, any fixed symbol between a particular symbol and a pixel of the CCD array There are no requirements for relationships.

For optical discs, for example, as the disc rotates under the sensing mechanism, A particular horizontal symbol position during a symbol blow is located at the same pixel of the CCD array. It does not need to be read by the file. In fact, the specific symbol position is the sensor position error tolerance of the locating mechanism, inaccurate centering of the disk on its axis, and Due to the error tolerance of the tracks on the There are some things that cannot be revealed. The track that follows the function of the sensor positioning mechanism is It is not necessary to operate with the same degree of precision as was required with prior art mechanisms.

A large error in sensor positioning is when the sensor moves in a radial direction and A CCD array such that it can be within the sensing area or field of view of the sensing device. is allowed by overscanning the y at its end.

``Overscanning'' refers to scanning the film beyond the boundaries of a block of symbols. However, this can be done at a rate faster than the Nyquist sampling rate. It should not be confused with "oversampling," which is taking a sample at .

As a result of the distortion of the disk, the line of the symbol on the film relative to the CCD array Although static torsion may develop, such torsion is compensated for by twisting the CCD array. There's no need. This is because, as discussed further below, the dyntal information is This is because the image is restored by driving the two-dimensional image representation.

Vertical optical oversampling means that the optical sensor is This is achieved by scanning the This scanning speed reduces optical aliasing. should be chosen to be the least. Vertical optical sampling rate and Optical aliasing is the optical filtration that results from the relative aperture of pixels versus symbols. It is a function of the interaction between the Luther effect and the line scan speed of the COD.

The vertical optical sampling rate is the horizontal optical sampling rate. It doesn't have to be far off. This is because the symbols are "smeared" by the rotation of the disk. tend to be stretched, which reduces the harmonic information content of the symbol. Because it does.

The rotation of the disk cooperates with the scanning of the CCD array12, resulting in two types of scanning required by the system. One of the directions is given. The exact scanning speed of the CCD depends on the rotational speed of the disk. It can be modified to follow short-term and long-term changes. In the operation of optical discs Although significant changes are unlikely to occur, in the present invention, the magnetic tape drive mechanism or magnetic strip short-term and long-term velocity changes that can be encountered in various devices, such as semi-scanning of top media. Substantially allowed. This aspect of the invention is described in further detail below.

2. Video fist processor FIG. 4 shows the interconnection of an embodiment of a CCr optical sensor and a video processor 120. It is a functional block diagram showing.

The output of the CCD array 30 and therefore the optical sensor 1. The output of the OQ is a wide bandwidth It is a pulse amplitude modulated analog signal like a video signal. This signal is The black level of this signal is passed through the low-pass filter 40 for each scan. Later, in the DC Kelamp 42, the Telezine signal was converted into the Telezine receiver. is clamped to DC in a similar manner. CCr) array is black red at the end of each scan. In order to give a bell signal, it must be overclocked. clamped The video signal provided by the CCD array 30 electrically converts the optical sample provided by the CCD array 30. The signal is passed to an 8-bit ADC 44, which samples the signal. Generated by ADC44 The 8-bit samples generated are stored in constant speed memory (RAM) 52.

Scanned images taken out by rotation of the disk and electrical sampling by AI) C44 The CCD array 30 stores in the RAM 52 the records transmitted by the optical disk. An oversampled digital signal of a two-dimensional image representation of a signal is given. available.

Electrical sampling or resampling of optical samples by AT) C44 The practical requirements for converting a sample into a format suitable for further processing in the digital domain. This is a matter. Electrical resampling samples from Ar) C44 The optical sampling information is 256 in 8-bit bytes suitable for digital processing. is expressed as the dispersion level of

As mentioned above, the line scanning speed of the CCD array 30 is shorter than the optical scanning speed. According to the changes in the rotational angular velocity of the disk, so that both periodic and long-term changes are allowed. It can be changed. between adjacent symbol blocks in a preferred embodiment of the storage medium. By providing a protective band, the angular velocity can be determined by the CCD array 30. can be obtained from a video signal-like signal generated by This signal predominates low A frequency component is a signal generated in response to a guard band. This dominant low circumference The wave number component is a direct measure of the current rotational angular velocity of the optical disc.

The scanning speed of the CCD array 30 and the clock speed of the Ar) C44 are expressed as the disk rotation angle. Variable or programmable locking mechanism to follow speed, band pass Filter 46, phase locked circuit (P1.I,) comparator 48, and frequency divider Provided by 50. The bandpass filter 46 has a guard band that is an optical sensor. centered on the nominal velocity through the structure. By P T, L comparator 48 Then, the signal received from the filter 46 is sent to the PLT, and the output signal is sent to the frequency divider 5. It is compared with a reference signal derived from dividing by zero. PT, L48 The output is applied to the CCD array 30 and ADC 44 as a clock synchronization signal. . Thus, the scanning speed of the CCD array and ADC depends on the change in the rotational angular velocity of the optical disk. closely follows the development.

As mentioned above, a feature of the present invention is that large variations in storage media drive speeds are not expected. This is especially important in other embodiments.

CCD array 30 and ADC 44 can be clocked to the same programmable lock. By synchronizing the sampling functions, each sampling function runs in synchronization with each other. This reduces the occurrence of undesirable artifacts that would otherwise occur if the operation were asynchronous. There is a tendency to

3. Image processor FIG. 5 shows an improved resolution of the image representation stored in RAM 52 and an optical storage medium. digital information corresponding to the value of optically encoded information transmitted by a body Functional blocks illustrating a preferred embodiment of an image processor 140 that generates It is a diagram. Pattern alignment 60 determines the position of one or more alignment patterns within the image representation. is upsampled by the reconstruction filter 62 (up processing by constraining the area within the image representation that must be management requirements are lowered. The image representation is further processed by adaptive equalization 64 and recorded. The effects of inter-signal interference are reduced. The adaptive threshold 66 allows the Responding to digital information 2! l! Value data is generated. That is, as stated above For the preferred embodiment of the optical storage medium, a 1 is generated in response to each transparent symbol. , 0 are generated in response to each opaque symbol.

Correctable errors detected in binary data by Error Detection and Correction (Er) C) 68 errors are corrected.

In one embodiment, reconstruction filter 62 provides a two-dimensional filter for video The image representation generated by the optical processor 120 is stored on an optical storage medium. It is applied to improve the resolution of two-dimensional image representations of transmitted symbols. child In this specification, a two-dimensional wave of ing”), which has the property of reconstruction-wave or image enhancement.

This embodiment also uses adaptive equalization 64 to reduce intersymbol disturbances from upsampling. The filtered image is reduced by passing it through an adaptive fishing line two-dimensional filter. An adaptive threshold 66 determines the binary representation of the symbol in response to the equalized image. generated. The outputs of adaptive equalization 64 and adaptive threshold 66 are equalization filter coefficients. Used to adapt numbers. Adaptive threshold 66 allows the threshold to It is adapted in response to the statistical characteristics of the output of adaptive equalizer 64.

Restructuring to improve resolving power - wave and equalization to reduce intersymbol interference The processing requirements for filtering are inversely related to the amount of symbol oversampling. O By making the oversampling speed sufficiently fast, resolution and intersymbol interference can be reduced. problems can be reduced or even eliminated. In practical systems, electro-optical and electronic Due to the cost and availability of equipment, system designers have the ability to restore symbols and enhance images. It is necessary to balance the amount of oversampling with the processing power required for required.

In one embodiment of the invention, the center of the symbol passes through the center of the disk. From the intersection of the radial line of ll1lN and the concentric arc centered on the disk center The intersection points of the grid to be formed are determined. Field the position of two or more symbols A set of positional references is established by determining within the Significantly reduces the amount of processing required to determine the position of all other symbols in the field be done. Although an alignment pattern is not required to implement the invention, the preferred embodiment uses an alignment pattern at each corner of each symbol block to determine the position reference. It reduces the amount of processing required. 2D image showing the exact position of each alignment pattern The expected position of each symbol center in the image representation by determining in the representation can be established with reasonable accuracy. Once the semiotic center in the image representation is established, the notation The level of light transmitted by the symbol at the center of the symbol is an image of a binary value of 1 or a binary value of 0. In order to determine whether each symbol in the page expression is represented by Compared against a threshold. When performing these functions, image processor 1 40 causes video processor 1 to operate in response to signals received from optical sensor 100. 20 operates on a two-dimensional image representation of the field generated by 20.

In image processor 140, the binary representation of the information conveyed by the symbol is To determine the location of a symbol within an image representation and determine whether the symbol is reflective or non-reflective. Verify the value of light transmitted by each symbol and determine whether it is a reflective or non-reflective symbol. Response 1. generated by generating 1 or 0 respectively. It will be done.

After finding the alignment pattern for each corner of the field, all records in the field are A grid of positional references that coincides with the center of the number can be determined. Actual example In some cases, distortion of the lattice can occur due to deformation of the storage medium, such as twisting. Symbol block Use four alignment patterns, one on each of the four corners of the lock, to position the grid lines. By linearly interpolating the position between alignment patterns, we can solve any linear It can also handle distortion.

If searching for a specific alignment pattern by pattern-alignment 60 If not possible, locate the unknown alignment pattern within the given field. It can be determined relative to the position of other alignment patterns.

After the location of one or more alignment patterns is determined, a reconstruction filter 62 The resolution of the image representation in the vicinity of each symbol is determined by a two-dimensional interpolation or reconstruction filter. is applied to the image at each expected symbol center. Ru. Test whether a symbol is reflective or non-reflective by measuring the amount of light reflected at the center of the symbol. It is desirable to judge based on evidence. Oversampling speed is slow Because of this, samples will generally not have been acquired at the symbol center. death However, by using a reconstruction filter to increase the resolution of the image, If the sample at the center of the issue had actually been obtained, what would it be? It is possible to predict whether

This prediction is performed using a two-dimensional reconstruction filter that upsamples the image representation. is achieved. Effective fourth-order upsampling of the sample is expected Achieved by interpolating values from samples in the image representation closest to the symbol center. will be accomplished. Effective upsampling allows samples to be obtained by chance. The closest sample is obtained at the location where the symbol is centered, rather than at any location. It will be done.

Alternatively, in other embodiments, the optical It is possible to avoid reconstruction filtering by performing bar sampling.

However, it is important to do some kind of wave to normalize the resulting image. Naturally desirable.

As discussed above, the precise nature of whether a sign is reflective or non-reflexive Decisions are hampered by intersymbol interference. Adaptive equalization 64 eliminates intersymbol interference. Additional digital filtering or “equalization” can reduce or ideally eliminate ” will be held.

The image representation in RAM 52 is processed by reconstruction filter 62 and adaptive equalization 64. reflected at or near the symbol center by a threshold 66. The amount of light is compared to a threshold to determine whether the symbol is reflective or non-reflective. compared. In fact, the adaptive threshold 66 allows The 8-bit value representing the shade of gray is translated into a binary representation. This is one or Select higher thresholds and apply these thresholds to 8-bit values It is done by Such a threshold value depends on the reflectance of the optical disc, the brightness of the illumination, Can be dynamically changed to track symbol density and other optical variables. Wear.

Reconstruction filtering, equalization, and adaptive thresholding do not form part of the invention. Therefore, details will not be described in this specification.

The EDC 68 provides detection and correction of errors incurred during the symbol recovery process. . , ED techniques are well known in the art and are not discussed herein.

C. Digital storage in video signals A storage medium for storing a video signal, for example a televised signal, may include a laser or Magnetic discs such as video discs and home recorded video cassette tapes Tape included. The information stored on these media can also be in the form of analog signals. It is.

One aspect of the invention is to store digital information in conjunction with conventional video storage techniques and devices. It operates to store information in the video signal. During playback, digital information is A two-dimensional image of a symbol representing digital information can be created in the same way as discussed above regarding optical media. By constructing a digital sufficient bandwidth and signal-to-noise to record the symbols used to represent the file information. It is assumed that the signal has the same ratio (SNR).

Home Video Cassette Tape Recorder Incorporating Preferred Embodiments of the Invention In this case, a video-like signal representing binary symbols is inserted into the video stream. . For example, for recorders for NTSC television signals, these symbols are the signals corresponding to the first 75 and last 75 scan lines of each 525 scan line image. recorded during the section.

Figure 6 shows a two-dimensional representation of the Shigeru frame of NTSC Television Studio 200. It is shown. The first 75 and last 75 scan lines of each image frame are 220 and 222, respectively. The frame that transmits this image The portion of the frame is represented by area 210. During playback, the first 75 and the most The video signal that creates the border for the next 75 scan lines is sent to the TVIL receiver. It is also possible to provide a video screen that is easier to transmit and accept.

To simplify the discussion, we will introduce the first 75 and last 75 lines that transmit digital information. The tree scan lines are called "digital scan lines."

Equipment used to record and playback video signals typically has significant jitter. is introduced into the video signal.

Because the timing of the start of each scan line and the duration of each scan line can vary considerably, The digital information can be recovered without any kind of correction to the time base of the signal. is difficult.

The present invention provides a high degree of time stability for equipment used to record and playback video signals. Does not require qualification. A signal representing each digital scan line is received and oversampled. pulled. The samples for each digital scan line are stored in RAM. A single row of the constructed two-dimensional image is represented. A 2D image was constructed Afterwards, timebase corrections can also be applied. That is, for each row in the image You can also align the starting points with each other to determine the duration of each row. The center of each symbol The location of each row is estimated by interpolating within the determined length of each row.

By performing one-dimensional filtering or upsampling of each row, the expected symbol An estimate of the sample value at the center is obtained.

Insert alignment patterns or special columns of symbols at the beginning and end of each digital scan line can assist in timebase correction, but this is not always necessary. . Referring again to FIG. 6, areas 232 and 236 define each digital scan. The alignment patterns at the beginning and end of the line are respectively expressed. To area 234 Thus, the portion of each scan line that carries symbols representing digital information is represented.

Special Table 16-503197 (11) Continuation of front page (81) Designated countries EP (AT, BE, CH, DE.

DK, ES, FR, GB, GR, IT, LU, MC, NL, SE), AU, CA , Fl, JP, KR, No, U (72) Inventor Mandel, Douglas Evanor California, United States 4408 Towninteeth Street, San Francisco, 94114 (72) Inventor Richards, Martin John California, USA a state 28 Circle Road, Redwood City, 94062

Claims (6)

[Claims] 1. device for recovering digital values represented by symbols transmitted by a medium And, a receiving device for receiving a signal from the medium representing the symbol; A sampling device for sampling the signal to generate samples, the sampling device comprising: the speed of arrival of symbolic representations in said signal is at least twice the speed of arrival of symbolic representations in said signal; a guiding device for guiding the expression of the symbol from the sample; detection responsive to the representation to recover the digital value represented by the symbol; equipment A device consisting of. 2. 2. The apparatus according to claim 1, wherein the guiding device generates an image table of the symbol. A device through which reality is guided. 3. 3. Apparatus according to claim 1 or 2, wherein the signal comprises multiple dimensions of symbols. structure, the sampling device causes the signal to be one or more of the multidimensional structures. the target at a rate more than twice the rate of arrival of symbolic representations in the signal corresponding to dimensions greater than or equal to The device to be made into a book. 4. 4. The apparatus according to claim 1, 2 or 3, wherein the detector device and a time base of said symbol is determined in response to said representation. 5. Information transmission medium consisting of a storage medium having one or more tracks of symbols and each of the tracks has two or more symbols extending the width of the track. a system in which the symbols are encoded two-dimensionally within each of the tracks; Place. 6. 6. The information transmission medium according to claim 5, wherein the track is two-dimensionally encoded. A medium consisting of blocks of symbols.