Limited play data storage media and method for limiting access to data thereon

#The present invention is related to storage media. More particularly, the present invention is related to limited play storage media.

#Optical, magnetic and magneto-optic media are primary sources of high performance storage technology which enables high storage capacity coupled with a reasonable price per megabyte of storage. Use of optical media has become widespread in audio, video, and computer data applications in such formats as compact disc (CD), digital versatile disc (DVD) including multi-layer structures like DVD-5, DVD-9, and multi-sided formats such as DVD-10, and DVD-18, magneto-optical disc (MO), and other write-once and re-writable formats such as CD-R, CD-RW, DVD-R, DVD-RW, DVD+RW, DVD-RAM, and the like, hereinafter collectively “data storage media”. In these formats, data are encoded onto a substrate into a digital data series. In pre-recorded media for optical media, such as CD, the data are typically pits and grooves formed on the surface of a plastic substrate through a method such as injection molding, stamping or the like.

#In some applications, it is desirable to have a limited life for an optical disc. For example, sample computer programs are provided to potential customers in order to entice them to purchase the software. The programs are intended to be used for a limited period of time. Additionally, music and movies are currently rented for a limited time period. In each of these applications and others, when that time has expired, the disc must be returned. A need exists for machine-readable optical discs that do not need to be returned at the end of a rental period. Limited-play discs provide a solution to this problem.

#FIG. 1 is absorption spectra of a colorless polycarbonate disc, oxidized leuco methylene blue in a poly(methyl methacrylate) film, and molded substrate discs from 3 polycarbonate formulations containing compounded dyes.

#FIG. 2 depicts the average reflectivity of a disc coated with a leuco methylene blue solution in ambient room conditions over time.

#FIG. 3 depicts the reflectivity kinetics for sandwich formatted discs compared to topical and 2-coat topical coatings.

#In this specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meaning.

#The singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.

#“Optional” or “optionally” mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.