How DVD Recorder Technology Works

Recording Technology

DVD recorders record via laser onto a blank disc. A DVD has the samediameter and thickness as a CD and is made using the same manufacturingmethods and materials. DVDs resemble CDs with encoded data in the formof small pits and bumps in the track of the disc. A DVD is made up ofseveral layers of plastic about 1.2 millimetres thick and every layeris composed by injection moulding polycarbonate plastic. The disc isformed with microscopic bumps arranged as a single, continuous spiraltrack of data.

After the polycarbonate pieces are formed, a thin reflective layer islayered onto the disc, covering the bumps. The inner layer is coatedwith aluminium, while the outer layer is coated with semi-reflectivegold for the laser to pass through the outer and onto the inner layers.After the formation of the layers, each layer is coated with lacquer,squeezed together and cured under infrared light. Some single sideddiscs have silk-screen labels put onto the non-readable side, whiledouble-sided discs are printed only on the non-readable area in themiddle of the disc, near the hole.

The writable layer of DVD has data in spiral form and the track circlesfrom the inside of the disc to the outside on single layer DVDs. Thismeans that a single-layer DVD can be as small as 12 centimetres indiameter. The microscopic dimensions of the bumps make the spiral trackon a DVD staggeringly long: if a single layer data track were stretchedinto a straight line, it would measure 7.5 miles long. A double sidedor double layer DVD would extend up to 30 miles!

Each data track is separated with just 740 nanometres and the elongatedbumps that constitute the track are 320 nanometres wide, 400 nanometreslong and 120 nanometres high. The familiar term ‘pits’ on a DVD appearson the aluminium side, but the side that laser reads from are bumps. Inorder to read bumps this small, you need an extremely precisedisc-reading mechanism. DVD discs lasts for years, since there is nophysical contact between the laser that reads the disc and the discitself.
 
Compatible Formats

Generally there are five recordable versions of DVD including DVD-R,DVD-RW, DVD+R, DVD+RW and DVD-RAM. DVD-RAM, DVD-RW and DVD+RW can berewritten thousands of times, while DVD-R and DVD+R can record dataonly once. DVD-RAM is a removable storage device for computers andvideo recording and is known for its flexibility in editing andrecording. DVD-R/RW and DVD+R/RW are highly competitive and have becomethe standard format; however they both have similar functions. Theintroduction of Set Top DVD recorders and DVD burners allows recordingin both + and – format. The recording speed is denoted in values of Xand 1X. This is equal to 1.321 MB equivalent to 9X CD-ROM and isconfined to computer based DVD recorders. Standalone units record inreal time (compressing the picture data with MPEG-2) 1X speed.

Conclusion

DVD recorders are becoming ever more advanced with some players nowintroducing hard disk based DVR that records onto large fixed harddisks. This feature is extremely useful as you can conveniently accessrecordings whenever you want to without the need to find and insert adisc. With its advanced technology and additional features, a DVDrecorder is a useful and, nowadays affordable device to protect yourfavourite movies and shows for posterity. 

Find a guide to buying DVD Recorders at www.tribaluk.com

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