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Disc Specifications
Drive
CD-ROM
CD-Recordable
(CD-R)
CD-ReWritable(CD-RW)
Function
Read Only
 Read Only
(CD/CD-ROM)
Write Once		 Read Only (CD/CD-ROM disc)
Write once (CD-R disc)
Overwrite (CD-RW disc :1000times)
Erase (CD-RW disc)
Recording Disc
 CD-R disc Both CD-R and RW disc
Recording Mode
 Sequential write Sequential write
Random write (supports UDF)
Usage
 CD Playback CD Playback
Data backup
CD, CD-ROM Edit
Document Preservation
Private CD,CD-ROM Copy		 CD Playback
Data backup
CD, CD-ROM Edit
Document Preservation
Private CD,CD-ROM Copy
+ Rewritable up to 1,000 times
Recording
Software
 Writing S/W
Device Driver		 Writing S/W : CD-R writing software compatible (data writing in CD-R standards possible)
Separate Device Driver to support UDF
Easy record and delete (compared to a floppy disc)
Recording Capacity
/ Laser Wavelength
 650 MB/780 nm 650 MB/780 nm
laser power
Read
:< 1mW
 Read : < 1mW
Write : 2x:4-11 mW		 Read : < 1mW
Write : 2x:8-14 mW

Disc Structure
[Fig 1. The facet & layer structure of Read Only CD]
[Fig 2. The facet & layer structure of CD-R disc]
[Fig 3. The Facet & Layer Structure of CD-RW Disc]
Layer Structure of Each Disc
CD-ROM
Printing Layer
Protective Layer
Recording Layer (Al)
Substrate (Polycarbonate)




CD-R
Printing Layer
Protective Layer
Reflective Layer (Ag)
Recording Layer (Dye)
Substrate (Polycarbonate)




CD-RW
Printing Layer
Protective Layer
Reflective Layer(Al)
Upper Dielectric Layer
Recording Layer(Ag-In-Sb-Te)
Lower Dielectric Layer
Substrate (Polycarbonate)
While CD-ROM reading is a process of following the spiral track of pits and lands,
writing to a CD-R/RW disc is a process of following the "pre-grooved" spiral track formed onto the disc surface. The Absolute Time In Pre-groove (ATIT) is encoded into the pregroove wobble signal.
The color of the CD-R disc surface varies based on the combination of the dye and the reflective
layer used.

Recording Principle

Physical Recording Principle
CD-R disc
The color of the CD-R disc varies depending on the kind of organic dye used in the recording layer. A laser beam which is very intensive is applied to the recording layer of organic dye. This results in the change of optical interference conditions, thus forming pits and lands.
CD-RW disc
The material of the CD-RW recording layer supports phase change. The phase change recording material changes repeatedly from an amorphous (formless) to a crystalline state, or phase-through exposure to variably-powered laser beams. When heated by a high-power beam, the material changes to its amorphous (recorded) phase. With a medium-power beam, the material forms its crystaline (erased) phase.
 
 
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