Capacitance Electronic Disc
This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages)
|
Media type | video playback media |
---|---|
Capacity | 60 minutes NTSC video per side, 27,000 still frames per side[1] |
Read mechanism | stylus |
Usage | Home video |
Released | March 22, 1981 |
Discontinued | 1986 (RCA)[2] |
The Capacitance Electronic Disc (CED) is an
First conceived in 1964, the CED system was widely seen as a technological success which was able to increase the density of a
The format was commonly known as "videodisc", leading to much confusion with the contemporaneous LaserDisc format. LaserDiscs are read optically with a laser beam, whereas CED discs are read physically with a stylus (similar to a conventional phonograph record). The two systems are mutually incompatible.
RCA used the brand name "
system is similar to that of CED.History
Beginnings and release
RCA began developing the videodisc system in 1964, in an attempt to produce a phonograph-like method of reproducing video under the name 'Discpix'. Research and development was slow in the early years, as the RCA CED team originally consisted of only four men,[8] but by 1972, the CED team had produced a disc capable of holding ten minutes of color video (a portion of the Get Smart episode "A Tale of Two Tails", re-titled "Lum Fong").[9]
The first CED prototype discs were multi-layered, consisting of a vinyl substrate, nickel conductive layer, glow-discharge insulating layer and silicone lubricant top layer. Failure to fully solve the stylus/disc wear and manufacturing complexity forced RCA to seek simpler construction of the disc. The final disc was crafted using PVC blended with carbon to make the disc conductive. To preserve stylus and groove life, a thin layer of silicone was applied to the disc as a lubricant.
CED videodiscs were originally conceived as being housed in jackets and handled by hand similar to LP records, but during testing it was shown that exposure to dust caused skipped grooves. If dust was allowed to settle on the discs, the dust would absorb moisture from the air and cement the dust particle to the disc surface, causing the stylus to jump back in a
After 17 years of research and development, the first CED player (model SFT100W) went on sale on March 22, 1981. A catalog of approximately 50 videodisc titles was released at the same time.
Demise
Several problems doomed the CED system before it was even introduced. From the early development of the CED system, it was clear that
"... Machiavelli noted that '..there is nothing more difficult to take in hand, more perilous to conduct, or more uncertain in its success, than to take the lead in the introduction of a new order of things...' At videodisc , I believe these words had special significance..."
|
Dr. Jay J. Brandinger, Vice President, RCA SelectaVision Videodisc Operations, June 27, 1986.[14] |
The extremely long period of development—caused in part by political turmoil and a great deal of turnover in the high management of RCA—also contributed to the demise of the CED system. RCA had originally slated the videodisc system for a 1977 release; at that point, discs were not able to hold more than 30 minutes of video per side and the nickel-like compound used to make the discs was not sturdy enough for manufacture. Signal degradation was also an issue, as handling the discs was causing them to deteriorate more rapidly than expected, baffling engineers.
Sixty minutes per side rendered it impossible for most movies over 120 minutes to be released on one CED disc. This was easily attainable on VHS and Betamax, as a T-120 VHS, for example (which holds two hours and four minutes of tape), could carry most of these movies. However, this was not the case on CED. Many popular films such as some of the James Bond series, Mary Poppins, Star Trek: The Motion Picture and Return of the Jedi had to be released on two CED discs. All three of these examples were typically seen on one VHS/Betamax cassette. [15]
RCA had projected that by 1985, CED players would be in close to 50% of American homes,[3] but the sales of players continued to drop. RCA cut the prices of CED players and offered incentives to consumers such as rebates and free discs, but sales only slightly improved. RCA management realized that the system would never be profitable and announced the discontinuation of production of CED players on April 4, 1984.[13] Remaining stocks of players were sold by dealers and liquidation retailers for as little as $20 each. Unexpectedly, demand for the videodiscs themselves suddenly became high immediately after the announcement; RCA alerted dealers and customers that videodiscs would continue to be manufactured and new titles released for at least another three years after the discontinuation of players. Less than a year after this announcement, the sale of discs began to decline, prompting RCA to abandon videodisc production after only two years, in 1986.[2] The last titles released were both in 1986.
Technology
CEDs are conductive vinyl platters that are 30.0 cm (11.8 in) in diameter. To avoid metric names they are usually called "12 inch discs". A CED has a spiral groove on both sides. The groove is 657 nm wide and has a length of up to 12 miles (19 km). The discs rotate at a constant angular speed during playback (450 rpm for NTSC, 375 rpm for PAL) and each rotation contains eight interlaced fields, or four full frames of video. These appear as spokes on the disc surface, with the gap between each field clearly visible under certain light. This meant that freeze frame was impossible on players without an expensive electronic frame store facility.
A keel-shaped stylus with a titanium electrode layer rides in the groove with extremely light tracking force (65 mg) and an electronic circuit is formed through the disc and stylus. Like an audio turntable, the stylus reads the disc, starting at the outer edge and going towards the center. The video and audio signals are stored on the Videodiscs in a composite analog signal which is encoded into vertical undulations in the bottom of the groove, somewhat like pits. These undulations have a shorter
The capacitive stylus pickup system which gives the CED its name can be contrasted with the technology of the conventional
In order to maintain an extremely light tracking force, the stylus arm is surrounded by coils, which sense deflection, and a circuit in the player responds to the signals from these coils by moving the stylus head carriage in steps as the groove pulls the stylus across the disc. Other coils are used to deflect the stylus, to finely adjust tracking. This system is very similar to—yet predates—the one used in
The disc is stored inside a caddy, from which the player extracts it when it is loaded. The disc itself is surrounded by a "spine", a plastic ring (actually square on the outside edge) with a thick, straight rim-like edge, which extends outside of, and latches into, the caddy. When a person inserts a caddy containing a disc into the player, the player captures the spine, and both the disc and the spine are left in the player as the person pulls the caddy out. The inner edges of the opening of the caddy have felt strips designed to catch any dust or other debris that could be on the disc as it is extracted. Once the caddy has been withdrawn by the person, the player loads the disc onto the turntable, either manually with all SFT and most SGT prefix RCA players or automatically with the RCA SGT-250 and all other models and brands of players. When playback has been started, the player spins the disc up to speed while moving the pickup arm over the disc surface and lowering the stylus onto the beginning of the disc.
When Stop is pressed, the stylus is lifted from the disc and returned to its parking location, and the disc and spine are lifted up again to align with the caddy slot. When ready, the slot is unlocked, and the caddy can be inserted and withdrawn by a person, now with the disc back inside.
Advantages
CED players, from an early point in their life, appealed to a lower-income market more than VHS, Betamax, and LaserDisc. The video quality (approximately 3 MHz of luma bandwidth for CED[1]) was comparable to or better than a VHS-SP or Betamax-II video, but sub-par compared to LaserDisc (about 5 MHz of luma bandwidth).
CED players were intended to be "low-cost" because they cost around half as much to manufacture as a VCR and had fewer precision parts.[18] The discs themselves could be inexpensively duplicated, stamped out on slightly-modified audio LP record presses.
Like VCRs, CED videodisc players had features like rapid forward/reverse and visual search forward/reverse. They also had a pause feature, though it blanked the screen rather than displaying a still image; many players featured a "page mode", during which the current block of four successive frames would be repeatedly displayed.
Since CEDs were a disc-based system, they did not require rewinding. Early discs were available only in
Like the LaserDisc and DVD, some CEDs feature random access, allowing users to quickly move to certain parts of the movie. Each side of a CED disc could be split into up to 63 "chapters", or bands. Two late RCA players (the SJT400 and SKT400) could access these bands in any given order. Unlike its laser-based counterparts, the chapters in a CED are based on minutes of the film, not scenes.
Novelty discs and CED-based games were produced whereby accessing the chapters in a specified order would string together a different story each time. However, only a few were produced before the halt of CED player manufacturing,[19] and CEDs are much more prone to wear and tear compared to LaserDisc.
Disadvantages
In comparison with
Since the CED system used a stylus to read the discs, it was necessary to regularly change the stylus in the player to avoid damage to the videodiscs, while worn and damaged discs also caused problems for consumers. When a disc began to wear, video and audio quality would severely decline, and the disc would begin to skip.[20] Several discs suffered from a condition called "video virus", where a CED would skip a great deal due to dust particles stuck in the grooves of the disc. However, playing the disc several times would generally solve this problem.[21]
Unlike VHS tapes, CEDs (along with LaserDisc) required a disc flip (however, some LaserDisc players were able to read both sides of the disc without physically flipping the disc, achieved by moving the laser from one side of the disc to the other, but this still resulted in a pause of playback during the change) at some point during the course of almost all films as only sixty minutes of video could be stored per side (75 mins on UK PAL discs due to the slower rotation speed); if a feature ran over two hours, it would be necessary to spread the feature over two discs.
In some cases, if a movie's theatrical running time was only slightly longer than two hours, studios would often trim short scenes throughout the movie and/or employ time compression (speeding the extra run time out of the film) in order to avoid the expense of issuing two discs.
This problem was not unique to CEDs: LaserDiscs presented the same difficulty, and some longer features, such as The Ten Commandments (1956), still required more than one tape or disc in the VHS, Beta, and LaserDisc formats. There were no two-disc UK PAL releases.
Less significant disadvantages include lack of support for
CEDs were also larger than VHS tapes, thicker than LaserDiscs, and considerably heavier due to the plastic caddies.
Available material
Players
CED players were manufactured by four companies—RCA, Hitachi, Sanyo, and Toshiba—but seven other companies marketed players manufactured by these companies.[23][24]
Media
Upon release, 50 titles were available for the CED; along with RCA (which included the company's partnership with
Market reception
Capacitance Electronic Disc's competitors, Philips/Magnavox and Pioneer, instead manufactured optical discs, read with lasers.[25] On April 4, 1984, after sales of only 550,000 players, RCA announced the discontinuation of CED videodisc players.[25] RCA's losses since the product's introduction were eventually estimated at $650 million.[26] The huge financial losses partially resulted in General Electric's acquisition of RCA in 1986, and the abandonment of the "SelectaVision" brand on all RCA video products.[25]
See also
References
- ^ a b "RCA SelectaVision VideoDisc FAQ - What are the technical specifications of the RCA VideoDisc system?". CEDMagic.com. Retrieved March 7, 2007.
- ^ a b "Memories of VideoDisc - CED Retailing at G&M Video in Indiana". CEDMagic.com. Retrieved March 11, 2007.
- ^ a b c "RCA SelectaVision VideoDisc FAQ - Why did the CED system fail to even come close to RCA's expected market penetration?". CEDMagic.com. Retrieved March 11, 2007.
- ^ Howe, Tom. "RCA Dimensia SKT425 CED Video Disc Player". www.cedmagic.com.
- ^ "VBT200 - The First RCA SelectaVision VHS Video Cassette Recorder (VCR)". CEDMagic.com. Retrieved March 14, 2007.
- ^ "HoloTape". CEDMagic.com. Retrieved March 6, 2007.
- ^ "MagTape". CEDMagic.com. Retrieved March 6, 2007.
- ^ "First Successful RCA SelectaVision VideoDisc Produced in 1972". CEDMagic.com. Retrieved March 14, 2007.
- ^ "Lum Fong - First Successful RCA VideoDisc Web Page". CEDMagic.com. Retrieved March 6, 2007.
- ^ "Comparison of 1977 CED Media to Final Production Media". CEDMagic.com. Retrieved March 10, 2007.
- ^ a b "Race For Your Life, Charlie Brown - The First RCA VideoDisc Title". CEDMagic.com. Retrieved March 10, 2007.
- ^ "Richard Sonnenfeldt's "VIDEODISK" Book Chapter". CEDMagic.com. Retrieved March 11, 2007.
- ^ a b "RCA SelectaVision VideoDisc FAQ - Why did RCA abandon further development of the CED system in April 1984?". CEDMagic.com. Retrieved March 11, 2007.
- ^ a b Jay J. Brandinger (June 27, 1986). Memories of VideoDisc (Capacitance Electronic Disc). Rockville Road, Indiana: RCA, Inc.
- ^ "Visual CED Title Database with 1024 x 1146 Images".
- ^ "Memories of VideoDisc - Milestones - The Last Production CED Title". CEDMagic.com. Retrieved March 14, 2007.
- ^ "Memories of RCA VideoDisc Main Page". CEDMagic.com. Retrieved March 14, 2007.
- ^ "The early days" by J. K. Clemens and E. O. Keizer. "Electronic Servicing & Technology" magazine 1982 May.
- ^ "A Walk Through the Universe CED Web Page". CEDMagic.com. Retrieved March 12, 2007.
- ^ a b "RCA SelectaVision VideoDisc FAQ - How long can I expect my CED VideoDiscs to last?". CEDMagic.com. Retrieved March 14, 2007.
- ^ "RCA SelectaVision VideoDisc FAQ - Why do some of my CED's skip, and what can I do to correct this?". CEDMagic.com. Retrieved March 14, 2007.
- ^ "CED Player Specifications". CEDMagic.com. Retrieved March 14, 2008.
- ^ "RCA SelectaVision VideoDisc FAQ - Who manufactured CED Players, and how many different models are there?". CEDMagic.com. Retrieved March 18, 2007.
- ^ "CED Player Name Brand Links". CEDMagic.com. Retrieved March 18, 2007.
- ^ a b c Hernandez, Daniela. "March 22, 1981: RCA SelectaVision Spins (Briefly) into Stores". Wired.
- ^ Peltz, James P. "RCA to Exit Videodisc Hardware Field" (AP story). Yonkers Herald Statesman, 5 April 1984, 18.
Further reading
- Cowie, Jefferson R. Capital Moves: RCA's Seventy-Year Quest for Cheap Labor. Ithaca, N.Y.: Cornell University Press, 1999. ISBN 0-8014-3525-0.
- Daynes, Rob and Beverly Butler. The VideoDisc Book: A Guide and Directory. New York: John Wiley and Sons, 1984. ISBN 0-471-80342-1.
- DeBloois, Michael L., ed. VideoDisc/Microcomputer Courseware Design. Englewood Cliffs, N.J.: Educational Technology Publications, 1982. ISBN 0-87778-183-4.
- Floyd, Steve, and Beth Floyd, eds. The Handbook of Interactive Video. White Plains, NY: Knowledge Industry Publications. 1982. ISBN 0-86729-019-6.
- Graham, Margaret B.W. RCA and the VideoDisc: The Business of Research. (Also as: The Business of Research: RCA and the VideoDisc.) Cambridge: Cambridge University Press, 1986. ISBN 0-521-36821-9.
- Haynes, George R. Opening Minds: The Evolution of Videodiscs & Interactive Learning. Dubuque, Iowa: Kendall/Hunt Publishing Co., 1989. ISBN 0-8403-5191-7.
- Howe, Tom. CED Magic: The RCA VideoDisc Collector's Guide. Portland, OR: CED Magic, 1999. ISBN 0-9670013-0-7. (CD-ROM)
- Isailović, Jordan. VideoDisc and Optical Memory Systems. Englewood Cliffs, N.J.: Prentice-Hall, 1985. ISBN 0-13-942053-3.
- Lardner, James. Fast Forward: Hollywood, the Japanese, and the VCR Wars. (Also as: Fast Forward: Hollywood, the Japanese, and the Onslaught of the VCR.) New York: W. W. Norton & Co., 1987. ISBN 0-393-02389-3.
- Lenk, John D. Complete Guide to Laser/VideoDisc Player Troubleshooting and Repair. Englewood Cliffs, N.J.: Prentice-Hall, 1985. ISBN 0-13-160813-4.
- Schneider, Edward W., and Junius L. Brennion. The Instructional Media Library: VideoDiscs (Volume 16). Englewood Cliffs, NJ: Educational Technology Publications. ISBN 0-87778-176-1. 1981.
- Sigel, Efrem, Mark Schubin and Paul F. Merrill. Video Discs: The Technology, the Applications and the Future. White Plains, N.Y.: Knowledge Industry Publications, 1980. ISBN 0-442-27784-9.
- Sobel, Robert. RCA. New York: Stein and Day/Publishers, 1986. ISBN 0-8128-3084-9.
- Sonnenfeldt, Richard. Mehr als ein Leben (More than One Life). ?, 2003. ISBN 3-502-18680-4. (in German)
- Journals:
- Video Computing
- The Videodisc Monitor
- Videodisc News
- Videodisc/Optical Disk Magazine
External links
- The 'Total Rewind' VCR museum, covering CED and other vintage formats
- RCA VideoDisc Web Site - CED Magic
- The LaserDisc Database - LD/CED/VHD discs, profiling and marketplace
- Electron Microscope Shows How CEDs are played
- Retro tech: The RCA CED Videodisc, Techmoan YouTube Channel, March 14, 2016
- The CED (RCA SelectaVision Videodisc), Technology Connections YouTube Channel, September 10, 2019
- RCA model SFT-100W "Selectavision" video disc player - National Museum of American History