How DVD players work

How they work

Much like a regular CD, DVD uses a laser to read microscopic pits on a disc to gather information and translate it into music, video or information. But that's where the similarity ends.

To make DVD as useful as it is, it had to hold much more information than standard CD. In order to achieve this data storage capacity, several daunting obstacles had to be overcome. For example, the microscopic pits had to be made smaller and placed much closer together. This was easy enough. However, the infrared laser commonly used for CDs could not read such tiny bits of information.

A unique, red laser that was developed by Panasonic's parent company, Matsushita Electric Industrial Co., Ltd., proved to be the perfect solution. It has a thinner beam with a shorter wavelength that could accurately read the densely-packed information. This paved the way to putting a stunning 4.7 gigabytes on a single layer of the new DVD disc.

But in order to meet the stringent requirements set forth by the motion picture and computing industries, it was apparent that even more data had to be put onto a single disc. The most efficient method was to construct a double-layered disc where the laser would read the first layer, then pass through a semi-transparent gold layer to read the second which is positioned less than 1/2 the width of a human hair below it. But there was a new problem to overcome. How do you join the two layers quickly and efficiently?

UV Bonding

A New Way Of Getting It Together. This time, Panasonic engineers developed a remarkable process that utilizes ultraviolet light and a photo-polymer resin to bring two DVD layers together. This patent-pending process can join two ultra-thin discs (0.6mm thick) in just five seconds. This means that dual-layer DVD could now yield an astounding 8.5 gigabytes of storage - more than 14 times that of standard CD-ROM!

But it doesn't end there. This highly efficient bonding process not only made double layering a reality, it now makes it possible to produce a DOUBLE-LAYER, DOUBLE SIDED DVD disc. This can store a dizzying 17 gigabytes of information, which is more than 11,800 floppy discs! They would create a pile 120 feet high!

CD Compatibility and The Hologram Lens

From the beginning, it was acknowledged that DVD players must be compatible with your existing CD and computer CD-ROM. Thanks to Panasonic, this has been achieved. Panasonic developed a dual-focus hologram lens that splits the beam of the already super-fine laser so that it can read two different levels simultaneously - at a depth of 0.6mm for DVD discs and 1.2mm for CDs. This revolutionary achievement eliminates the need for 2 separate laser systems and ensures full compatibility with your existing pre-recorded CD and CD-ROM libraries.

Video Compression Squeeze Play.

Moving images on a video disc consume enormous amounts of information. As incredible as the DVD capacity is, it would only yield 5 to 10 minutes of a movie. Enter MPEG-2, a data compression technology. Developed by the Motion Picture Experts Group, MPEG-2 is the system that is now used to encode satellite television signals.

Put simply, MPEG-2 condenses video by looking for redundant or repetitive image signals (such as the background of a static shot in a movie). Rather than continuously repeating this information, it uses it once until the scene or action changes. The result is the capability to encode up to 8 hours of digital video on a double-sided, dual-layer DVD!

The magic of DVD starts with several innovations that were developed by Panasonic. First, a unique red laser with a short wavelength is utilized to read the ultra small pits on a DVD disc. Second, to ensure compatibility with existing CDs and CD-ROMs, Panasonic developed a hologram lens which splits the laser beam so that it can focus on DVD data at a depth of .6mm, and on CD information which rests at 1.2mm deep.

Gold Layer

A dual-layer DVD disc is constructed of two thin substrates that are joined by a unique Panasonic bonding system. The first is semi-transparent and gold in color. The laser reads the information on this layer first.

UV Adhesive

The layers of a DVD disc are bonded by a Panasonic process that utilizes a photo-polymer resin. It starts out amber in color, but the ultraviolet light curing process will turn it clear so the laser can read through it.

Silver Layer

When the laser reaches the end of the first layer, it increases in power slightly and begins to read the second layer, which is silver in color. The switch in layers is seamless and allows you to watch movies non-stop, without flipping a disc over.

DVD Will Change the Way You Use Computers

Home entertainment isn't the only field that will be changed forever by DVD. Consider that today's CD-ROM holds an admirable 680 megabytes of information while a single-sided, dual-layer DVD holds 8.5 gigabytes! And that capacity will be doubled to 17 gigabytes when the double-sided, double-layered DVD hits the market!

Capacity isn't the only advantage that DVD has - it's a lot faster, too. CD-ROM retrieves data at 900 KB per second. DVD data is retrieved at 1,385 KB per second.

All of this means that PC users will be thrilled by new multimedia software with more interactive capabilities, digital surround sound, and fast access. Consider also that instead of low resolution video, which lasts only a few seconds on CD-ROM, the DVD-ROM will provide much longer, full motion, broadcast quality video. This has major implications in all forms of software - games, entertainment, education, business and networking.