DVC CASSETTE
The main domestic application of DVC is in compact camcorders, all of which use the mini-DVC cassette shown in Fig. 19.2. The ID terminal contacts 1, 2 and 3 have resistance values to ground, 4, which respectively indicate to the deck-control system tape thickness, type and grade. Some DV cassettes incorporate an internal memory chip
for storage of this ident data, plus a table of contents, TOC. In this case the four terminals function as serial data terminals for cassette memory-chip read and write. The cassette is 66×48×12.2 mm in size, and contains sufficient tape for one hour’s operation at the standard- play running speed of 18.831 mm/sec.
Tape
The tape ribbon used for DVC is 6.35 mm 1⁄4″ wide, 7 microns thick, and consists of five layers as shown in Fig. 19.3a. The magnetic layer is double-evaporated (Fig. 19.3b) for greater output and lower noise than conventional ME tapes. Other new features of DVC tape are the back coating layer, with very low friction; and the overcoat hard carbon layer with extra durability and abrasion resistance for improved reliability.