This document summarizes the history and types of CDs and DVDs. It discusses how they are manufactured by creating a glass master that is used to injection mold the discs out of polycarbonate. It describes the differences between CDs and DVDs in terms of size, data storage capacity, and technology. CDs can store 700MB of data while DVDs can store up to 17GB. The document also compares high definition formats Blu-ray and HD-DVD in terms of storage capacity, with Blu-ray having higher capacity of up to 200GB compared to HD-DVD's 60GB maximum.
3. History
• First public demonstration of CD is in 1976 By Sony.
• High Quality Audio CDs have been commercially
available from October 1982 By Philips
• The VCD standard was created in 1993 by Sony,
philips, Matsushita.
4. MANUFACTURING OF CD/DVD
It involves creation of a glass master
that is placed onto a stamper which
is then injected into a mold (shape
of a disc) made from polycarbonate
substrates. Data is then permanently
stamped or "pressed" onto the CD or
DVD and the end result is a fully
manufactured disc that is playable
across multiple platforms.
5. Types
• CD (Compact Disc)
• DVD (Digital Video Disc)
• HD-DVD (High Defination – Digital Video Disc)
• BD (Blue ray Disc)
6. CD
• 12 cm disk with plastics substrate, aluminum
coating and plastic cover
• 0.83 micron wide pits, 1.6 micron spacing
• Data storage capacity 700 MB
10. Limits the Data on a CD/DVD
● Each pit is one “bit” (0 or 1) of data
● How fast the CD turns (1.4 m/sec for single
speed)
● Rotation speed limit: about 52x (72.8 m/sec)
● Problem is lifetime of Blue laser approaching
1000 hrs
11. HD-DVD v/s Blue Ray DVD
● Next generation DVD format has two competitors.
● HD-DVD: Toshiba, NEC, Microsoft, entertainment industry.
● Blue Ray (BD): Sony, Hatachi, Panisonic, Apple etc .
● Blue Ray higher capacity (25 GB) vs HD (15 GB) .
● Hence shorter pits: Blue ray 0.16 μm, HD 0.205 μm .
● Problem is that Blue ray is much nearer the surface (0.1 mm) .
● Blue ray can have 8 layers, up to 200 GB, HD 4 layers, 60 GB.
● Sept 2008 Blue ray only 8% of market, DVD 92%.
● Blu-ray has a double layer storage size of 50 GB. While HD
DVD has a double layer storage size of 30 GB.