Does Any body know who invented CD/DVD? let's know it here

All of us use CD's & DVD's but most of them don’t know who invented and how it works



So. Let’s know about this 

History:

    David Paul Gregg first envisioned the optical or laser disc in 1958 and patented it in 1969.

Invention of CD:
       James Russell invented the compact disk in 1965.
James Russell was granted a total of
22 patents for various elements of his compact disk system. In the early 1970s, using video Laser disc technology, Philips' researchers started experiments with "audio-only" optical discs, initially with wideband frequency modulation FM and later with digitized PCM audio signals. The compact disc was thus developed by Philips from its own 12 inch Philips Laser Vision discs. At the end of the 1970s, Philips, Sony, and other companies presented prototypes of digital audio discs.


In 1974, an initiative was taken by L. Otters, a director of the audio industry group within the Philips Corporation in Eindhoven, the Netherlands. A seven-person project group was formed to develop an optical audio disc with a diameter of 20 cm with a sound quality superior to that of the large and vulnerable vinyl record. In March 1974, during a meeting of the audio group, two engineers from the Philips research laboratory recommended the use of a digital format on the 20 cm optical disc, because an error-correcting code could be added. It wasn't until 1977 that the directors of the group decided to establish a laboratory with the mission of creating a small optical digital audio disc and a small player. They chose the term "compact disc" in line with another Philips product, the compact cassette. Rather than the original 20 cm size, the diameter of this compact disc was set at 11.5 cm, the diagonal measurement of a compact cassette.

However, the compact disk did not become popular until it was mass manufactured by Philips in 1980.

Invention of DVD:

         DVD is the advanced version of CD which is evolved from the CD. It is a high-density CD.

Before the advent of DVD in 1995, Video CD (VCD) became the first format for distributing digitally encoded films on standard 120 mm optical discs.VCD was on the market in 1993. In the same year, two new optical disc storage formats were being developed. One was the Multimedia Compact Disc (MMCD), backed by Philips and Sony, and the other was the Super Density (SD) disc, supported by Toshiba, Time Warner, Matsushita Electric, Hitachi, Mitsubishi Electric, Pioneer, Thomson, and JVC.Representatives of the SD camp approached IBM, asking for advice on the file system to use for their disc as well as seeking support for their format for storing computer data.
DVDs were invented in the early 1990s (1993 is the answer shown on two different websites as a third said 1996), but they did not become popular until around the turn of the millennium. Until around 2001, people mostly still rented videocassettes. Their predecessor, laserdiscs, were available in the early 1990s (although they were very expensive and almost nobody had them), but they quickly became obsolete when the DVD was invented. Laser discs were like a hybrid of a vinyl record and a DVD: they were huge -- like 14 inch-wide -- DVDs with a big hole in the middle. Educational films were sometimes shown on them. Laserdisc players were basically just like DVD players- but much bigger.But the actual date  The date of 'early 1990s' is the best to quote. DVDs came on the market in the UK about 1999. A presentation was given about 'a new video medium' (which turned out to be DVD) in early 1998. 

DVD-R read/write side
Media type	Optical disc
Capacity	4.7 GB (single-sided, single-layer – common) 8.5–8.7 GB (single-sided, double-layer) 9.4 GB (double-sided, single-layer) 17.08 GB (double-sided, double-layer – rare)
Read mechanism	650 nm laser, 10.5 Mbit/s (1×)

Write mechanism	10.5 Mbit/s (1×)
Standard	DVD Forum's DVD Books and DVD+RW Alliance specifications

Disc shapes and diameters:
The digital data on a CD begins at the center of the disc and proceeds toward the edge, which allows adaptation to the different size formats available. Standard CDs are available in two sizes. By far, the most common is 120 millimeters (4.7 in) in diameter, with a 74- or 80-minute audio capacity and a 650 or 700 MB (737,280,000 bytes) data capacity. This capacity was reportedly specified by Sony executive Norio Ohga so as to be able to contain the entirety of Beethoven's Ninth Symphony on one disc. This diameter has been adopted by subsequent formats, including Super Audio CD, DVD, HD DVD, and Blu-ray Disc. 80 mm discs ("Mini CDs") were originally designed for CD singles and can hold up to 24 minutes of music or 210 MB of data but never became popular.[citation needed] Today, nearly every single is released on a 120 mm CD, called a Maxi single

Physical size	Audio Capacity	CD-ROM Data Capacity	Definition
120 mm	74–99 min	650–870 MB	Standard size
80 mm	21–24 min	185–210 MB	Mini-CD size
85x54 mm - 86x64 mm	~6 min	10-65 MB	"Business card" size

Inner structure OF a CD
A CD is a fairly simple piece of plastic, about four one-hundredths (4/100) of an inch (1.2 mm) thick. Most of a CD consists of an injection-molded piece of clear polycarbonate plastic. During manufacturing, this plastic is impressed with microscopic bumps arranged as a single, continuous, extremely long spiral track of data. We'll return to the bumps in a moment. Once the clear piece of poly carbonate is formed, a thin, reflective aluminum layer is sputtered onto the disc, covering the bumps. Then a thin acrylic layer is sprayed over the aluminum to protect it. The label is then printed onto the acrylic. A cross section of a complete CD (not to scale) looks like this:

Different types of CD, DVD
these Optical Disc are classified into many ways such as
CD': s-,        
             CD-R, CD-RW, 

DVD's:-      
             DVD-R, DVD-RW, DVD+R DL, DVD+R, DVD-RAM, DVD+R DL, MINI DVD-R, 
MINI DVD-R DL, MINI DVD+RW, 

Blue Ray- BD-R, BD-R-DL, BD-RE

Uses:-
 Ah.. Everyone know the uses of Cd&DVD, U can Use them as U wish (vadukunnodiki vadukunnantha):-)

So guys what you will say if any one asks you "who is inventor of CD/DVD?"
A:    David Paul Gregg started invention in the year 1958 & James Russell invented the compact disk in 1965

Abbreviations: 

CD: Compact Disc   (Everyone knows it)
DVD: Digital Video Disc/Digital Video Disc
BR: Blu-ray (invented by Sony corp).