Figure 1-2.
Half wrap and omega wrap
b. The dotted line in the center of each line represents the gap
through which the rotating heads would establish contact with the videotape
as it passes by. By using a tape path like this past the rotating heads, it
is possible to put more video information on a single track, a whole field
or 262.5 lines instead of 16.4 lines per track, as the quad-heads VRs
required. Because of the new design, only one or two heads were required on
a rotating wheel instead of four.
The new helical scan design produced
slanted video tracks like the example in Figure 1-3, as opposed to almost
perpendicular video tracks produced by quad-head VRs as was shown in Figure
1-1.
Figure 1-3.
Helical tape wrapping system
c. After much development of the helical scan system on 1/2-inch reel-
to-reel type systems, the industry developed two unique systems of
packaging, storing, and loading the tape on VRs. At this time new VRs had
also been developed to handle this new system of tape. The cartridge (CART)
and CASSETTE systems were developed for ease of loading and handling by the
operator.
Now the recorder does all the loading by just inserting the
cassette or cartridge into the recorder draw, which activates the mechanical
arms that open the dust cover and retract the tape that wraps it around the
head drum. After this operation the tape is ready to record or play back.
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