A CD-R (English: Compact Disc Recordable) is a write-once CD, which can be described with a conventional burner. Data, photos, videos or music can be stored on and played with a CD drive. The still blank CD -R is often referred to as a blank CD.
It consists of an injection molded transparent plastic substrate made of a polycarbonate, a microscopic spiral groove is in the surface thereof. This minimal pit is used to guide a laser writing ( "burning" ) of digital information generated by heating the absorption properties and hence the reflectivity of a special organic dye layer (dye called ) in the smallest areas, the so-called pits changed. These pits can then (of a weaker laser, the color layer is not changed ) are read out again by the reflected radiation intensity is transformed into an electrical signal by analyzing the change in reflectivity of an overlying ( vapor-deposited ) of silver or gold layer. To protect the layers ( color and reflection layer) on the metal reflection layer ( silver usually, rare gold) applying a thin, transparent layer of lacquer before the decorative printing is carried out. Since silver tends to take black sulfide compounds, early CD - Rs with silver coating had a short life expectancy. This was increased significantly by evaporation of an aluminum layer behind the silver layer.
The capacity of a CD - R ( for data CDs ) usually given both in minutes ( for audio CDs ) and in MB.
Depending on the quality and type of the blank and after burner can also be burned outside of the shared area in the ATIP ( overburn ). However, this can result in errors or loss of data in this area. Not all drives support overburning.
For sizes beyond the original 650 MB/74 min can cause playback problems in some CD drives, as the ruts are closer to each other to achieve the higher capacity.
The multi-level CD -R has three times the capacity of a standard CD -R's, but never went into series production.
History / CD-R today
The CD -R was introduced to the public in October 1988 after three years of development work by the Japanese company Taiyo Yuden.
The first CD- Rs for the entire market were established in 1992 ( after the introduction of the CD- R and the Photo CD by Kodak and Philips at Photokina ). Some of the first manufacturers were Taiyo Yuden, Kodak, Maxell and TDK. Since then, the CD -R has been continuously developed so that today can be fired with a 56- fold higher rate than was possible in the first CD -R. The improvements were mainly used the dyes of the CD- R, the embodiment of the groove and the coating process.
Although the CD -R was originally developed in Japan, since 1998, Taiwan produced the largest amount of CD -R. The Taiwanese production made more than 70 % (2003: 10.5 billion CD-R). Manufacturers from Taiwan include Daxon ( BenQ ), Ritek, Prodisc and CMC Magnetics, who however often outsourced much of the CD production to Malaysia, Hong Kong and the People's Republic of China. Outside of Taiwan Moser Baer India is the largest CD -R manufacturers.
At present there are three basic dye mixtures for CD- Rs:
There were more earlier, rather insignificant dyes, for example the so-called formazan, which was developed by Eastman Kodak Company. Formazan could be on the market do not prevail and is no longer available.
Can not always be inferred from the color of the recording layer of the CD -R on the composition of the dye used. Other color additives and the type of reflector material used (silver or gold ) change the color impression. It is therefore not possible to conclude solely from the shimmering gold that it is a CD -R with phthalocyanine dye and a gold reflective layer.
It is also not possible to conclude from the dye used directly on the durability of the CD -R. Other factors such as reflectivity, surface protection or sealing play a greater role. Since the reflectivity of an intact CD -R reached a value that is higher than the set for CD -ROM and CD -DA minimum all intact CD drives can read CD -Rs. However, since the typical reflectivity of the CD -R is below the typical reflectivity of a CD, get dusty drives first problem in reading CD - Rs before they even read any more CDs.