Abstract:
A method for storing data including the steps of providing a sheet of media and printing a raw data pixel on the sheet of media, the raw data pixel being printed at a density and a color such that the raw data pixel represents a data point. The method further includes printing an associated compensated data pixel on the sheet of media, the compensated data pixel being printed at a density and a color, wherein the density and color of the compensated data pixel are related to the density and color of the associated raw data pixel by a predefined relationship. The method also includes the step of repeating the first and second printing steps until the desired data is stored on the sheet of media.

Description:
[0001]    This application claims priority to Japanese Patent Application No. 2001-184085, filed May 16, 2001.  
         BACKGROUND OF THE INVENTION  
         [0002]    Media storage devices, and more particularly, read-only media storage devices, such as CDs, DVDs, magnetic tapes and computer diskettes are widely used to store various data. The data stored on such devices can be nearly any machine readable data, including text, movies, books, pictures, computer code and software, bar codes, sounds (including music), recording applications including those using compressed data, and the like. However, the data storage capacity and/or data storage density of conventional media storage devices may be limited. Accordingly, there is a need for an improved method and apparatus for recording data.  
         SUMMARY OF THE INVENTION  
         [0003]    The present invention is a method and apparatus for recording data. In one embodiment, the method and apparatus records various colors at various discreet densities to represent the data. In particular, in one embodiment, the invention is a method for storing data including the steps of providing a sheet of media and printing a raw data pixel on the sheet of media, the raw data pixel being printed at a density and a color such that the raw data pixel represents a data point. The method further includes printing an associated compensated data pixel on the sheet of media, the compensated data pixel being printed at a density and a color, wherein the density and color of the compensated data pixel are related to the density and color of the associated raw data pixel by a predefined relationship. The method also includes the step of repeating the first and second printing steps until the desired data is stored on the sheet of media.  
           [0004]    Other objects and advantages will be apparent from the following description and the appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    [0005]FIG. 1 is a front view of a media card upon which data may be recorded;  
         [0006]    [0006]FIG. 2 is a cross section of a sheet which can be used to form the media card of FIG. 1;  
         [0007]    [0007]FIG. 3 is a detailed view of the data storage region of the media card of FIG. 1;  
         [0008]    [0008]FIG. 4 is a graph illustrating one relationship between the density of a color and the classification of such density;  
         [0009]    [0009]FIG. 5 is a chart illustrating one system for matching numbers with data read from a media card;  
         [0010]    [0010]FIG. 6 is a chart illustrating one classification scheme for data compensation;  
         [0011]    [0011]FIG. 7 is a chart illustrating another classification scheme for data compensation; and  
         [0012]    [0012]FIG. 8 is a partially exploded schematic view illustrating one method for forming the media card of FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0013]    [0013]FIG. 1 illustrates a color code media card  10  which may be used in one embodiment of the present invention. The illustrated media card  10  includes an upper region  12  upon which a title or name of the media card  10  may be printed such that a user can read and ascertain the nature of the media card  10 . The media card  10  may include a central region  14  upon which other indicia may be printed. For example, in one embodiment, a drawing, picture or photograph may be printed in the central region  14 , and the title or label of such drawing, picture or photograph is printed in the upper region  12 . The card  10  may also include a data storage region  16  upon which stored data is located or printed. The data stored or printed in the data storage region  16  preferably corresponds to the indicia printed in the central region  14  and upper region  12 . However, it should be understood that the media card  10  need not necessarily include the upper region  12  and/or the central region  14 , and may instead include only the data storage region  16 .  
         [0014]    As shown in FIG. 3, the data storage region  16  may include a plurality of data pixels  18  arranged in a grid. The majority of the data pixels  18  are preferably either normal (i.e. raw) data pixels  20  or compensated (i.e. adjusted or redundant) data pixels  22 . As shown in the enlarged portion of FIG. 3, in the illustrated embodiment, each compensated data pixel  22  is located immediately to the left of an associated normal data pixel  20 , although the spacing relationship between the normal  20  and associated compensated  22  data pixels may be varied as desired. Each of the normal  20  and compensated  22  data pixels may include a plurality of different colors printed thereon in a fully overlapping manner, with each color being printed at one of a plurality of predetermined intensities or relative color densities. However, each normal  20  and compensated  22  data pixel may include only a single color printed thereon, or may include only various shades of a single color printed thereon.  
         [0015]    Thus, each normal  20  and compensated  22  data pixel may have a single color to the eye, but be made of, for example,  3  primary colors, each primary color being printed at a specific relative density. In one embodiment, each of the normal data pixels  20  and compensated data pixels  22  may include up to three colors (i.e., cyan, magenta and yellow, or red, green and blue) printed thereon, with each of the colors being printed on the media card  10  in one of four discrete relative densities (i.e., 0%, 33%, 66% and 100%). Of course, a variety of other colors, differing number of colors and differing number of discrete densities (i.e. from 2 to 10 or more) may be used without departing from the scope of the invention. Thus, in the illustrated embodiment, each normal  20  or compensated  22  data pixel may include up to three colors printed thereon in an overlapping manner, with each color being printed at one of four different densities.  
         [0016]    The differing densities and colors of the normal  20  and compensated  22  data pixel correspond to data characteristics represented by such pixel. For example, FIG. 4 illustrates a graph which represents one scheme for ascertaining or determining a data characteristic of a measured normal  20  or compensated  22  data pixel, for a given color, based upon the relative density of that color. As shown in FIG. 4, if the relative density of a color of a pixel is from 0% to 10%, the density is classified as “Classification 1.” If the density is from 28% to 38%, the density data is classified as “Classification 2” and so on. In other words, density classification 1 is preferably 0% and includes densities ranging from 0% to 10%; density classification 2 is preferably 33%, and includes densities ranging from about 28% to 38%; density classification 3 is preferably about 65%, and includes densities ranging from about 61% to 71%; and density classification 4 is preferably about 100% and includes densities ranging from about 90% to 100%. Of course, as noted above, the classifications of density can be broken down in nearly any desired manner.  
         [0017]    In order to read the data from the data storage region  14  of the media card  10 , a piece of optical reading equipment, such as a color optical scanner, densitometer, calorimeter, spectrophotometer or the like, scans and reads each of the data pixels  18  on the data storage region  14  of the card  16 . At each pixel location  18 , the colors and density of each color printed thereon is determined. As shown in the enlarged portion of FIG. 3, the data storage region  16  may include a plurality of timing marks  28  located throughout the data storage region  16  at known, regular locations. The timing marks  28  may be printed as black) with a density of about 100% (or any other predetermined color/density pattern. The timing marks  28  may be regularly spaced throughout the data storage region  16  and be located at, for example, every four columns and four rows of the data pixel grid. In this manner, the optical scanner can use the timing marks  28  to track its location on the data storage region  16 .  
         [0018]    Once the optical scanner has scanned the data pixel or pixels  18  of the data storage region  16  and determined the density of each of the possible colors printed thereon, a processor, controller, CPU, computer or the like receives the raw data and processes the raw data to convert the raw data into decimal or binary numbers based upon a predetermined table or algorithm. The controller may be part of the optical scanner, or may be separate or part of a separate component that is coupled to the optical scanner. FIG. 5 illustrates a chart for converting the various combinations of colors and densities that may be found on a normal  20  or compensated  22  data pixel of the illustrated embodiment into a decimal or binary number. For example, if the optical scanner reads red, green and blue colors each having the lowest density (classification 1), then the controller may assign this combination a decimal number of 0. Continuing the example, as shown in FIG. 5, the controller may assign a combination of R4, G4, B4 (i.e., red, green and blue, each of the highest density), a decimal number of 63. Of course, a wide variety of relationships between the color/density characteristics and output data may be used. Thus, in order to properly read and unscramble the raw data, the controller must be supplied with a chart or algorithm which determines the relationship between the measured colors/densities and the output data, such as decimal or binary numbers, letters, text, characters, and the like.  
         [0019]    Thus, it can be seen that a single data point or pixel  18  can represent the number of combinations equal to (the number of classifications of density) raised to the power of (the number of colors utilized). For example, in the illustrated embodiment four densities and three colors are used such that each data point or pixel  18  can represent a number anywhere from 0 to 63 (that is, 4 3  or 64 data combinations).  
         [0020]    As noted above, each normal data pixel  20  may include an associated compensated data pixel  22 . The normal data pixel  20  and associated compensated data pixel  22  cooperate to provide redundancy of data and reduce the number of errors associated with reading the media card  10 , for example, due to cross talk. In particular, each compensated data pixel  22  is related to the associated normal data pixel  20  by a predetermined relationship, such as the relationship illustrated in the chart of FIG. 6. As shown in FIG. 6, if the normal data pixel is printed with a density classification of 1, the compensated data pixel is printed with a density classification of 3. If the normal data pixel includes a density classification of 2, the compensated data pixel includes a density classification of 4, and so on as illustrated in FIG. 6. FIG. 7 illustrates another table illustrating an alternate relationship between the normal data pixels  20  and their associated compensated data pixels  22 .  
         [0021]    In general, if the relative density of a raw data pixel  20  is greater than about 50%, then the density of the associated compensated data pixel  22  is preferably less than about 50%. Conversely, if the density of a raw data pixel  20  is less than about 50%, then the density of the associated compensated data pixel  22  is preferably greater than about 50%. The color of each normal data pixel and the associated compensated data pixel preferably remains the same for both the normal and compensated data pixels, although the colors may be varied according in a predetermined manner if desired. For example, as shown in the enlarged portion of FIG. 3, using the data compensation scheme of FIG. 6 a raw data pixel  20 ′ which is R3, G4, B2 is “converted” to a compensated data pixel  22 ′ of R1, G2, B4.  
         [0022]    In this manner, when the optical scanner reads the data storage region  16  of the media card  10 , the optical scanner can check whether the read or measured characteristics of the normal data pixel  20  matches with the read or measured characteristics of the compensated data pixel  22  according to the predefined relationship. If the controller determines that the normal data pixel  20  and compensated data pixel  22  do not properly match, the controller may then determine that one of the normal  20  or compensated  22  pixels has been incorrectly printed and/or read, and the processor may then proceed to institute various data correction measures (i.e., removing the problematic data pixel, determining the data pixel value based upon surrounding data pixels and other indications, etc.).  
         [0023]    Because lower density classifications are lighter, it is more likely that the optical scanner may improperly read the lower density classifications (i.e., density classifications 1 and 2) of a data pixel  18 . Thus, the compensation scheme illustrated in FIG. 6 ensures that the lighter densities (classifications 1 and 2) are compensated into a darker, and more easily readable, density classification (classifications 3 and 4, respectively). Thus, if the normal data pixel  20  and compensated data pixel  22  do not properly match, one method for accommodating such a condition may be to consider that the data pixel (either normal or compensated) with the higher density classification represents the correct data pixel.  
         [0024]    As shown in FIG. 3, the data storage region  16  may also or alternately include a calibration section  30  which may include colors and densities printed thereon in a known, predetermined manner. In this manner, the optical scanner can read and/or scan the calibration section  30  in order to calibrate the optical scanner to the specific nature of the colors printed on that media card  10 . In the illustrated example, the calibration section  30  includes all possible 64 pixels printed thereon so that the optical scanner can read and calibrate each of the possible data pixels. For example, when the card  10  is printed with a darker density than expected, density classification 1 may be erroneously printed at 30%, density classification 2 may be erroneously printed as 60%; density classification 3 may be erroneously printed at 90%; and density classification 4 may be erroneously printed at 100%. In this manner, the various compensation schemes can compensate for differences in printing equipment, differences in printing quality by media lot, or differences in optical reading equipment.  
         [0025]    Although each pixel  18  may be of nearly any desired size, in one embodiment the size of each pixel is about 100 microns by 100 microns, and each pixel  18  may include, for example, 100 dots (i.e. 10 dots by 10 dots) therein. Thus, the method and apparatus for recording data of the present invention enables large volumes of data to be accommodated and stored in a relatively small space.  
         [0026]    The media card  10 , and particularly the data storage region  16 , can be formed by nearly any color printing process, such as screen printing, laser printing, ink jet printing, digital printing using photosensitive imaging media, photographic printing, “polaroid”-type printing, thermal-autochrome printing, disublimation and the like. However, it may be preferred to print the media card  10 , and particularly the data storage region  16 , using a self-contained photohardenable imaging media process, such as by using the self-contained photohardenable imaging media sold by Cycolor Inc. of Miamisburg, Ohio, which provides high resolution color printing with rich gradations and rich color expressions. Furthermore, although pixels or other components may be referred to herein as being “printed,” or being “printed” at a specific of predetermined color or density, it should be understood that such pixels or other components need not necessarily be “printed” by a printer but could instead be formed by nearly any printing or image-forming process.  
         [0027]    In one embodiment, the media card  10 , and particularly the data storage region  16 , is created on a sheet of media  40  including microcapsules  50  encapsulated therein. As shown in FIG. 2, in this case the sheet of media  40  may include a support layer  42 , a self-contained photosensitive and pressure sensitive layer  44  located on the support layer  42 , a barrier layer  46  located over the photosensitive and pressure sensitive layer  44  and a protective layer  48  located over the barrier layer  46 . The support layer  42  may be a variety of materials, such as PET (poly ethylene terephthalate (polyester)), polypropylene, synthesized paper, resin coated paper and the like.  
         [0028]    The photosensitive and pressure sensitive layer  44  preferably includes a plurality of microcapsules  50  dispersed therein, with each microcapsule  50  including a liquid color former or color precursor encapsulated therein. The contents of each of the microcapsules  50  are preferably light sensitive and the color former inside each microcapsule  50  preferably corresponds to one of three primary colors. The photosensitive and pressure sensitive layer  44  may also include a developer material or resin  52  suspended therein which can react and make colors with a color former. The barrier layer  46  may be any of a wide variety of materials, including but not limited to water soluble resins such as PVA (polyvinyl alcohol) or gelatin. However, the barrier layer  46  is optional and need not be included. The protective layer  48  may provide a water resistant and scratch resistant surface to the imaging media, and may be a wide variety of materials, including but not limited to water soluble resins such as PVA (polyvinyl alcohol), gelatin or water dispersible resins such as acrylic latex or other polymer lattices. The photosensitive and pressure sensitive layer  44  is preferably applied to the support  42  by any of a variety of coating methods such as blade coating, air coating, curtain coating and the like.  
         [0029]    As shown in FIG. 8, the sheet of media  40  of FIG. 2 may be placed on a support sheet  56  such that the sheet  40  is located below a recording head, generally designated  58 . The recording head  58  may include a liquid crystal display panel  60 , a back light  62  which can emit light of various colors, and a support panel  64  located above the back light  62 . The liquid crystal display panel  60  can be controlled to form areas of light and dark located thereon in a desired pattern such that the light of various colors emitted from the back light  62  can be transmitted and blocked in the desired manner such that a liquid crystal display panel  60  operates as a mask. In this manner, selected microcapsules  50  inside the photosensitive and pressure sensitive layer  44  can be exposed to actinic radiation to harden the liquid color former in selected microcapsules  50  in the desired manner and pattern. The liquid color former in the remaining, unexposed microcapsules  50  remains in its liquid form. In other words, the media sheet  40  is image-wise exposed to actinic radiation to form a latent image in the form of hardened, partially hardened and unhardened microcapsules  50 .  
         [0030]    Once the specific colors of the microcapsules  50  have been hardened in the desired patterns, the media card  40  and support sheet  56  are conveyed downstream through the nip of a pair of opposed pressure rollers  66  which break the unhardened capsules  50 . The color former released from the ruptured microcapsules  50  reacts with the developer resin located in the photosensitive and pressure sensitive layer  44  to cause the desired pattern of colors to form in the media card  10 . Such a printing system is described and shown in U.S. Pat. Nos. 4,399,209; 4,416,966; 4,440,846; 4,766,050 and 5,783,353, the contents of which are hereby incorporated by reference. Once the data storage region  16  is formed on the media in the desired manner, the card can be stored or transported and used as a media storage device in the manner described above.  
         [0031]    Having described the invention in detail and by reference to the preferred embodiments, it will be apparent that modifications and variations thereof are possible without departing from the scope of the invention.