Summary of How VCRs Work
The article explains the historical impact and internal complexity of VCRs, describing videotape construction, VCR functions (tape handling and signal reading), and key milestones (first reel-to-reel recorder in 1956, Sony's first inexpensive VCR in 1969, VHS in 1976, Blockbuster in 1985). It highlights why video recording requires different techniques than audio due to vastly greater data density.
Parts used in the VCR Inside Look Project:
- Top and bottom pieces of the outer shell (cassette)
- Moving, spring-loaded door (cassette)
- Two spools to hold the tape (cassette)
- 800-foot (244-m) long, 1/2-inch (1.3-cm) wide oxide-coated Mylar tape
- Several low-friction rollers to guide the tape
- Two spring-loaded locks to prevent tape unrolling (cassette)
- Several screws to hold the cassette together
- VCR lever to release and open cassette door
- Pin to disengage spool locks
- Motorized tape loading and ejection systems (VCR)
- Complex motorized tape path mechanisms (VCR)
- Drum-mounted rotating read/record heads (VCR)
The VCR marks one of the most important events in the history of TV because, for the first time, it gave people control of what they could watch on their TV sets. Prior to the VCR, there was no such thing as a video store, and when you consider that there is now a video store on nearly every street corner in the United States, you can see what a big impact the VCR has had!
The other interesting thing about VCRs is how incredibly intricate and interesting they are inside. They are certainly the most complex mechanical systems most people own outside of their automobiles, yet VCRs can cost as little as $75! There are motorized tape loading and ejection systems, complex motorized tape paths, drum-mounted rotating read/record heads… VCRs really are neat inside!
In this article, we will look inside a VCR to understand the basics of its operation, both from a tape transport standpoint and a signal standpoint. Once you have seen what is going on, you will be both amazed and impressed!
The VCR Tape
A VCR tape is pretty intricate device in its own right, and it’s a classic miracle of mass production. It is amazing what you can buy for $2!
If you take a video tape apart, you will find that it contains:
- The top and bottom pieces of the outer shell
- A moving, spring-loaded door to protect the tape
- Two spools to hold the tape
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- An 800-foot (244-m) long, 1/2-inch (1.3-cm) wide piece of oxide-coated Mylar tape that acts as the recording medium
- Several low-friction rollers to guide the tape across the front of the shell
- Two spring-loaded locks to prevent the tape from unrolling inside the cassette
- Several screws to hold the whole thing together
When the tape is inserted into a VCR, the VCR uses a lever to release and open the door, exposing the tape. It also inserts a pin into the hole to disengage the two locks on the spools. At that point, the drive can extract the tape and play it.
The VCR
In 1956, the first commercial reel-to-reel videotape recorder was created by Charles Ginsburg and Ray Dolby while working for the Ampex Corporation. This new device was a major development for television broadcasters because it marked the first time that shows could be recorded and broadcast later. Prior to 1956, all shows on television were live.
Sony created the first inexpensive VCR in 1969. In 1976, the VHS tape format appeared and began its domination of the market. Video stores were soon to follow. Blockbuster opened its first video store in Dallas, TX, in October 1985, and now has over 8,000 stores.
The VCR itself has two jobs:
- It must deal with the tape — an extremely thin, fairly fragile and incredibly long piece of plastic. As we will see in a moment, it is amazing what a VCR does with the tape.
- It must read the signals off of the tape and convert them to signals that a TV can understand.
Both of these are formidable tasks, and the second one was a big technological challenge. In sound recording, the sound information is stored linearly on the tape. That is, the tape moves past the recording head and the sound information is laid down as a long line following the length of the tape. The tape might move past the head at a speed of 2 or 3 inches (5 – 8 cm) per second. A video signal contains perhaps 500 times more information than a sound signal, so the same approach cannot work. The tape would have to be moving past the head at a rate of many feet per second.
For more Detail: How VCRs Work
- What made the VCR historically important?
The VCR gave people control of what they could watch on their TV sets for the first time, enabling the rise of video stores. - What are the two main jobs of a VCR?
The VCR must handle the tape and read the signals off the tape converting them to TV-compatible signals. - What does a VCR tape contain inside its cassette?
A cassette contains top and bottom shell pieces, a spring-loaded door, two spools, about 800 feet of oxide-coated Mylar tape, low-friction rollers, two spring-loaded locks, and screws. - How does a VCR access the tape inside a cassette?
The VCR uses a lever to open the cassette door and inserts a pin to disengage the spool locks so it can extract the tape. - Why can't video be recorded on tape the same way as audio?
Video signals contain roughly 500 times more information than sound, so linear recording at audio tape speeds would require the tape to move many feet per second. - When was the first commercial reel-to-reel videotape recorder created and by whom?
In 1956 by Charles Ginsburg and Ray Dolby at the Ampex Corporation. - When did the VHS format appear?
The VHS tape format appeared in 1976. - What consumer milestone followed the appearance of affordable VCRs and VHS?
Video stores proliferated, and Blockbuster opened its first store in October 1985.
