CD-R

A CD-R (Compact Disc-Recordable) is a thin (1.2 mm) disc made of polycarbonate with a 120 millimetre or 80 millimetre diameter that is mainly used to store music or data. However, unlike conventional compact disc media, a CD-R has a core of dye instead of metal. A standard CD-R has a storage capacity of 74 minutes of audio or 650 Mebibyte of data. Non-standard CD-Rs are available with capacities of 80 minutes/700 MbB, which they achieve by slightly exceeding the tolerances specified in the Orange Book (CD standard) CD standards. Most CD-Rs on the market are of the latter capacity. There are also 90 minute/790 MiB and 99 minute/870 MiB discs, though they are rare. The polycarbonate disc contains a spiral groove to guide the laser beam upon writing and reading information. The disc is coated on the side with the spiral groove with a very thin layer of a special dye and subsequently with a thin, reflecting layer of silver, a silver alloy or gold. Finally, a protective coating of a photo-polymerizable lacquer is applied on top of the metal reflector and cured with ultraviolet-irradiation. A CD recorder is a special type of CD-ROM drive used to write onto blank CD-R media. A laser is used to "burn" small ''pits'' into the dye so that the disc can later be read by the laser in a CD-ROM drive or CD player. The laser used to write CD-Rs is an infrared laser which emits laser radiation at a wavelength of 780 nm. The reflectivity in the pit area is different (lower) than for the unchanged dye area, because the refractive index of the dye is lowered upon "burning" a pit. Upon reading back the stored information, the laser operates at a low enough power not to "burn" the dye and an ''optical pick-up'' records the changes in the intensity of the reflected laser radiation when scanning along the groove and over the pits. The change of the intensity of the reflected laser radiation is transformed into an electrical signal, from which the digital information is recovered ("decoded"). The decomposition of the dye in the pit area through the heat of the laser is irreversible (permanent). Therefore, once a section of a CD-R is written, it cannot be erased or rewritten, unlike a CD-RW. A CD-R can be recorded in multiple sessions. When looked at by the naked eye, the part of the CD-R which contains data will be slightly darker than areas which are not written to. Using this method, you can get a rough estimation of the amount of data on a CD-R, and whether or not it has been written to. == History == The CD-R, originally named CD write-once (WO), specification was first published in 1988 by Philips and Sony in the 'Orange Book'. The Orange Book consists of several parts, furnishing details of the CD-WO, CD-MO (magneto-optic), and CD-RW (rewritable). The latest editions have abandoned the use of the term "CD-WO" in favor of "CD-R". Written CD-Rs and CD-RWs are fully compatible with the CD (Red Book) and CD-ROM (Yellow Book) standard. They use Eight-to-Fourteen Modulation, EFM, CIRC error correction plus the third error correction layer defined for CD-ROM. Compatibility of CD-R and conventional read-only discs, CD and CD-ROM, is a miraculous achievement which was made possible by the dye materials developed by Taiyo Yuden. A blank CD-R is not "empty"; it has a groove with a wobble, which is used for timing and adjustement of the disc rotation frequency during writing. First CD-Rs were produced in 1994. Also the disc contains a ATIP which is a data track contaning information about the media (legnth etc.). Among the first manufacturers were the companies Taiyo Yuden, Kodak, Maxell, and TDK. Since then, the CD-R was further improved to allow writing speeds as fast as 54x (as of 2004) relative to the first 1x CD-Rs. The improvements were mainly due to optimisation of special dye compositions for CD-R, groove geometry, and the dye coating process. Low-speed burning at 1x is still used for special "audio CD-Rs", since CD-R audio recorders were standardized to this recording speed. There are three basic formulations of dye used in CD-Rs: #Cyanine dyes were the earliest ones developed, and their formulation is patented by Taiyo Yuden. Cyanine dyes are naturally green in color, and are chemically unstable. This makes cyanine discs unsuitable for archival use; they can fade and become unreadable in a few years. Many manufacturers use proprietary chemical additives to make more stable cyanine discs. #Azo dye CD-Rs are blue in color, and their formulation is patented by Mitsubishi Chemicals. Unlike cyanine, azo dyes are chemically stable, and typically rated with a lifetime of decades. #Phthalocyanine dye CD-Rs are usually silver or gold. The patents on pthalocyanine CD-Rs are held by Mitsui and Ciba Specialty Chemicals. These are also chemically stable, and often given a rated lifetime of hundreds of years. Unfortunately, many manufacturers add additional coloring to disguise their cyanine CD-Rs, so you cannot determine the formulation of a disc based purely on its color. Similarly, a gold reflective layer does not guarantee use of phthalocyanine dye. Note also that rated CD-R lifetimes are estimates based on accelerated aging tests, and lifetime can vary considerably based on how you store the discs. For optimum lifespan, CD-Rs should be stored vertically to prevent warping, inside archival plastic cases which use a ridged ring around the spindle which grips the disc. This ridge prevents the surface of the disc from coming into contact with anything during storage. Discs should be stored in cool, dark conditions, with controlled humidity. Avoid using any kind of label on the CD surface, and avoid use of printed inserts using anything other than water-based inks. Although the CD-R was initially developed in Japan, most of the production of CD-R had moved to Taiwan by 1998. Chinese manufacturers supplied more than 70% of the worldwide production volume of 10.5 billion CD-Rs in as of 2003. There was some incompatibility with CD-Rs and older CD-ROM drives. This was primarily due to the lower reflectivity of the CD-R disc. In general, CD drives marked as 8x or greater will read CD-R discs. Some DVD players will not read CD-Rs because of this change in reflectivity as well. == See also == * CD-ROM, GD-ROM * DVD, DVD-R, DVD plus R, DVD plus R DL * CD recorder == External links== * The CD-R FAQ: http://www.cdrfaq.org/ CD 120 mm discs Audio storage Video storage

CD-R

Needs to be merged: A CD recorder is a computer peripheral that writes data to a CD disk. There are two main types -- CD-R and CD-RW. CD-R is CD-Recordable. CD-RW is CD-Rewritable. CD recorders are also known as CD burners. To record a CD is often called burning a CD. ==MiB vs. MB== -I thought the 650MB CD-R stored 650MiB, not 650000000B: 333000sectors * 2048bytes/sector / 1024 / 1024 = 650.390625. see http://www.cdrfaq.org/faq07.html#S7-6. -Yeah, me too. CD-Rs seem to be measured in MiB (though they say MB as just about nobody uses the term MiB, while DVD-Rs seem to be measured in GB (not GiB). - Yep. The reason why it says MB on Dan100's CDs is because the MiB terminology has not been adopted anywhere in the industry, thus the "(though MB is printed on CDs as the binary prefixes haven't caught on in the industry)" I added to the article. (odd that you would change it back to MB but not change that). So, I suppose it would be possible to refer to it as a 650MB CD (though confusing, and we want to eliminate as much of that as possible in an encyclopedia, right?), but the way it was before I edited it "650MB (not MiB)" was flat out wrong. User:Psxer 08:08, 7 Jan 2005 (UTC) Wuh? CDs, like any other storage media, are measured in megabytes. As said, these 'MiBs' have "not caught on in the industry", and they certainly haven't outside it, either. User:Dan100 19:02, Jan 7, 2005 (UTC) I mean, I kinda see where you're coming from, but the bottom line is that MB is the accepted and universally-used terminology, for all its faults. User:Dan100 19:22, Jan 7, 2005 (UTC) Oh and it's madness to use "650.390625", as that rounds to 650. You would no more say "650.390625" rather than "650" than, when asked by a collegue how far you travel in to work each day, you would say "19.74673 km" instead of "20 km". User:Dan100 19:26, Jan 7, 2005 (UTC) == burning pits? == it isn't burning pits into the dye; it's changing the color of the dye to make it less reflective, right? - User:Omegatron 05:30, Jan 15, 2005 (UTC)

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Words begining with CD-R:

CD-R
CD-R
CD-Recorder
CD-Rewritable
CD-ROM
CD-ROM
CD-Rom
CD-rom
Cd-ROM
Cd-rom
CD-ROM_drive
CD-RW