Imaged medium comprising sensor-readable indicia

Details Imaged medium comprising sensor-readable indicia Imaged medium comprising sensor-readable indicia

1998-12-31

2003-04-01

Hess, Bruce H. (Department: 1774)

Stock material or miscellaneous articles

Structurally defined web or sheet

Discontinuous or differential coating, impregnation or bond

C383S093000, C383S113000

Reexamination Certificate

active

06541100

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to an article having encoded data on a surface thereof and a method for storing data by applying encoded data onto a surface of an article.
BACKGROUND OF THE INVENTION
Applying visually observable, digitally readable data on an article is known. For example linear bar-codes are printed on many articles today for identification and inventory control. The information in such bar-codes can be easily retrieved by a scanner and interpreted by a computer. A disadvantage of these types of bar-codes is that they are visible to the naked eye and interfere with viewing of other information which may be on the article beneath the bar-code. Alternatively the bar-code may be printed in an area which contains no additional underlying information however this option limits the amount of information that can be encoded in the bar-code and can prevent digital reading and translating the encoded data during normal observation of the article. Restriction of the encoded data to small areas also defines the of amount of encoded data. Therefore the prior art generally refers to storage of very small information bits, such as a stock item number or a postal zip code.
UV absorbing materials are known to be useful for invisible markings. Examples are disclosed in patents U.S. Pat. No. 5,502,304, U.S. Pat. No. 5,401,561, U.S. Pat. No. 5,554,842, U.S. Pat. No. 5,629,512 and U.S. Pat. No. 5,693,693 where UV light is used to illuminate marks on documents such as mail pieces so that the marks can then be read in the red or green portion of the electromagnetic spectrum. UV fluorescent labels (U.S. Pat. No. 5,401,561) have been disclosed for security marking of basic commodity or collector's article. The marks described in these patents are either small pictures, several numerical figures or linear bar-codes. Printing of magnetic data strips is also known for encodement of data onto articles. The magnetic strips have been applied to the backsides of films for the storage of data. Magnetic data has disadvantages as well. First data stored in this method has to be retrieved with a magnetic head employing relative motion between the head and magnetic strip for signal reproduction. Critical alignment between the read head and the data track, as well as maintaining intimate contact between the read head and magnetic strip are important considerations that make magnetic strip reproduction unattractive option for data reproduction.
Also magnetic recording media has limited life in terms of wear-out and inherent loss of the magnetically recorded data over time. Moreover magnetic materials are not invisible. The data capacity is limited by the need to find available blank space on an article to use these materials to avoid impacting the normal viewing of the article.
There also exists much prior art which involves motion picture sound tracks. Several patents describe UV fluorescent materials such as toners in U.S. Pat. No. 4,308,327, UV fluorescent layers (U.S. Pat. No. 3,926,633) or IR absorbing dyes (U.S. Pat. No. 5,030,544).
Many materials have been disclosed for formulation into invisible inks and used to mark various articles with invisible marks. None of the prior art teaches or enables how to place a data code directly on the surface of an article containing existing information on the surface thereof, such as a photographic or printed image, without impairing that information and still allow for interpretation and retrieval of the data with an appropriate sensor. This invention relates not only to the discovery of specific materials for achieving this goal but more to those conditions which allow invisible marking, preferentially a two-dimensional data pattern, such as a two-dimensional bar code or a dot code, to be applied to an article where such article has underlying information, such as a color photographic or printed image. This is Especially true when the data is large and the pattern containing the data needs to take up large portions of the surface area and avoidance of covering at least a portion of the image region is not possible. Obviously it is detrimental to viewing the image if it is obscured or damaged in any way by the presence of a visible pattern of data overlying the image. One solution to this problem is disclosed in U.S. Pat. No. 5,644,447. In the system described in the '447 patent a black two dimensional barcode is printed on the back side of the image, on a blank portion of the image surface area or on a whitened out region of a image print, what is described in their patent art as an optical modulation layer, which further obscures the underlying image. Our invention avoids these limitations and permits application of data directly over the image (or other information) without obscuring or damaging the underlying image (or other information).
PROBLEM TO BE SOLVED BY THE INVENTION
There exists a need to use invisible materials to apply, especially large, data files on article, in specific conditions which overcome the problems and limitations of the prior art.
A basic problem that has to be overcome to achieve the dual goal of invisibility and then readable, is that the many of the materials referred to as “invisible inks” are only invisible when applied at very low levels. In other words the sensitivity of a sensor device has to be better than the human eye at these low levels. If the material absorbs light in the visible region (400-700 nm), this burden is the largest to overcome. Even when a material has an absorption maximum in the UV and IR regions frequently there is still have some absorption in the visible region. Because of this basic problem we have found that many of the materials disclosed for this use in the prior art are barely detectable by an appropriate sensor on white backgrounds at the levels where they are no longer visible. When the additional burden of an underlying colored image is added, most of those materials are no longer detectable by the sensor. The problem of detectability is greatest when an underlying colored image dye absorbs light even slightly where the overlying data material absorbs. The detection by a sensor relies on a material, upon illumination by an appropriate illuminant, to cause an attenuation of light relative to the background. The material of the data can absorb the light and emit it (for example fluoresce) at a different wavelength than the background reflection wavelength or the material can absorb the light and convert it to a non-irradiative energy (for example heat). Regardless of the mechanism, in conditions where the materials would be invisible these attenuations tend to be small. When applied over colored image dye these small signals are generally overwhelmed by large light absorption of the image dyes. Therefore the attenuation of the data carrying material is itself attenuated by the light characteristics of the underlying image often rendering them undetectable.
SUMMARY OF THE INVENTION
However we have discovered special conditions under which this problem can be overcome.
In accordance with one aspect of the invention, there is provided a method of storing encoded data on an article comprising applying said data on a surface of the article, as an encodement invisible to the human eye under normal viewing conditions. In preferred embodiments of the invention, the data is encoded as a two dimensional bar code.
In accordance with another aspect of the invention, there is provided the materials for storing data on an article such that these materials are invisible to the naked eye and do not interfere with the normal observation of the article under normal viewing conditions.
Yet another aspect of the invention provides for the selection of data carrying materials whose absorption and emission properties are substantially different from that of the underlying materials. Another aspect of the invention is a condition such data carrying material must have a minimal amount of absorption in visible region at a level which is detectable by a sensor at a wavelength which enabl

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