The DVD works in the same way, except that both the discs are double-sided. Instead of just reading one side for information, the laser reads both sides, something like our old vinyl records.
If you're in the movie rental business that means more long-term profits as you won't have to pay for replacement versions after multiple plays. It has the added advantage that the local franchise won't have to worry about whether you rewind it or not. In addition, because of special features within the television set DVD player units, it will be impossible for these sets to "read" and play pirated copies of movies on DVD, a problem that has plagued Hollywood's video market abroad.
This micrograph shows a commercial die, into which CD manufacturers inject molten polycarbonate plastic to form the pits and lands of an individual disc. DVD digital video disc is a technology based on optical data storage similar to compact disc CD.
Optical data storage is a method of storing digital information 1's and 0's by using light to read the information. Analog information is converted into digital information, which is then encoded onto the disc from the inside edge out. Digital data are encoded by means of pits on the recording layer of the disc. The pits and the separations between pits, called lands, vary in length to represent the digital information stored in the disc. The pits are arranged in a track that forms a spiral pattern on the recording layer of the disc.
The disc revolves in a circular motion inside the player, while an optical head laser slowly moves outward and remains focused on the pits. The laser beam is reflected back to a detector when it hits the lands, and it is scattered away from the detector by the pits. The transition between a pit and a land corresponds to a "1" in the digital bit stream. A DVD can store over two hours of video on one layer of the disc. In comparison to the 74 minutes of data that a CD can hold, this capacity marks a vast improvement.
The smallest pits on a DVD are about 0. The pits are arranged in tracks called track pitch that are spaced much closer on a DVD 0. With this construction, a single layer, single-sided DVD can hold 4. Pits burned into a recordable CD-ROM, shown in the scanning electron micrograph above, are rougher around the edges than pits in a commercially stamped CD.
With such small pit areas, the number of possible errors in reading the disc is limitless. As a result, error correction storage has seen rapid development.
After manufacturing the DVD also, the working performance is tested. To see the adverse effects of these players in different temperatures, the tests will be carried out in excessive heat as well as humidity. Since most of the parts of a DVD player is made by suppliers, they rely on other companies for good quality. The DVD assemblers will set a minimum standard for the supplies that they buy from outside. This specification must be met by them. The lenses and mirrors should be highly polished and cleaned before placing them.
An article regarding the detailed working of a DVD has been explained earlier. Thanks for this information Pls Mr. As for me, am stil in my first year of 2yrs Dip in the study of Electrical and Electronics.
Therefore, I would realy like to learn more about Troubleshooting, and Repair of Consumer Electronics. I will realy appreciat whoever is willing to help me up. Please is it possible to improvise and obtain the voltage of the different part of the disk drive mechanism using a USB? If so, how can it be done. And can you also give more details on the working of the disc drive mechanism and optical reader mechanism?
Much More detailed with schematic diagrams. Thank you. I love this article. No the power requirement is 5 volts for logic and 12 volt for analog and 15 to 24 volts for the amplifier part.
Switched mode supply is used in the DVDs. Since most DVD players can also play audio CDs, if you buy a player with a high disc capacity you could store your whole CD collection in the machine. A dedicated remote , which only runs the DVD player A multibrand remote , which can control other components, like VCRs and TVs made by other manufacturers Usually, they only support the more common brands.
A learning remote , which can learn the signals from other remotes and assign them to a button This feature is useful if you have uncommon brands of components to control. DVD Extras. Because DVDs are so durable, film aficionados can watch a favorite movie repeatedly without the disc losing its quality. This is also good for parents whose children like to watch the same movies over and over again. DVD players allow you to find scenes, play them in slow motion or freeze a scene, and the video quality will remain the same.
An entire encyclopedia can fit onto one DVD, whereas other formats would require multiple discs. Read More. Audio and Video Outputs " ". DVD player video outputs from left to right: composite video, s-video, component video. Component-video outputs provide the highest quality video signal to your TV. They are quite rare right now; only the newest high-end TVs can support them. There are three separate connectors for component video output.
S-video outputs are more common. S-video provides a very good picture quality, and every DVD player has at least one of these outputs. Composite-video outputs are the most common type of output, and they provide adequate picture quality. Usually, they have a yellow plastic insert. Coaxial digital output and optical digital outputs provide the highest-quality audio. They send the digital sound information to the receiver for decoding.
You can use either one of these if you have a Dolby Digital receiver. DVDs work much the same way as conventional CDs. Just like in a CD, the information is coded as a series of tiny pits in the disk. The pits are organized on a spiral track in a structure similar to vinyl records.
By using a laser, these pits can be interpreted as binary code. When a smooth surface is read, the machine interprets the data point as a 0. When a pit is encountered, the data point is read as a 1. However, the key innovation that makes DVDs superior to CDs is the laser used to read and create the pits. DVDs use a shorter-wavelength, red laser that can place pits more densely on the surfaces of the disks.
This not only allows for more data, it also requires that the disks be only half as thick as conventional CDs. Consequently, two layers can be bonded together to create a double-sided disk which has the same thickness as a CD 1.
The DVD system has three features, which make it highly desirable including its high storage capacity, interoperability, and back-ward compatibility. In the early stages of DVD introductions, a single disk will hold as much as 4. In future releases of this technology, a disk may hold up to 17 GB. This amount of storage space will literally change the way computer programs are developed and will allow for the inclusion of more video clips.
The data format and laser used in DVDs will be the same for the computer players as for the television players. This will enable consumers to play the same disks in their computers that they play on their TV.
DVD players will also have the ability to play current technology CDs. In this way, consumers will not have to buy replacement products for their current CD collections. DVDs can be used for a variety of applications including movies, audio systems, computers, and video games. Since the in-formation stored on these disks are electronic, the picture quality is estimated to be three times better than conventional VHS pictures. Additionally, the picture will not degenerate with age or use.
Computer programs will also benefit from DVDs. Video games will also benefit from DVD technology. Since DVDs offer high memory and interactivity possibilities, video clips can be included to enhance the playing experience. Developing the ability to store data for later retrieval has always been important. The first true data storage and retrieval systems were journals and ledgers.
While they are still used today, they are slow, inefficient, and bulky. When the computer was being developed during the s and s, one of their main benefits was their ability to store and retrieve data quickly. This has now become one of the cornerstones of information storage and retrieval. Early computerized storage mediums included such things as punch cards, vinyl LPs, magnetic tape, cartridges, and magnetic disks. As computers improved, so did the data storage capabilities.
In the late s, the internal hard drive was introduced. Each of these data storage systems were developed to improve on the convenience and efficiency of the best storage methods available.
Many of these systems continue to be improved on even today.
0コメント