IEC 61904:2000 pdf download

IEC 61904:2000 pdf download.Video recording -Helical-scan digital component video cassette recording format using 12,65 mm magnetic tape and incorporating data compression (Format digital-L).
2.1.6 GuidIng groove
For correct insertion into the VTR, four guiding grooves for $ cassettes as shown in figures 1 and 2, and three guiding grooves for L cassettes as shown in figure 15 shall be provided.
2.1.7 Safety tab and safety plug
For $ cassettes, a safety plug at the supply reel side and a hole of minimum depth of 10 mm from datum plane Z at the take-up reel side shall be provided as shown in figure 2.
For I cassettes, a safety plug shall be provided at the takeup reel side as shown in figure 15.
2.1.8 IdentIfIcatIon holes
Five identification holes (holes 2 to 6) shall be located as specified in figures 2 and 15.
There is no hole for hole 1 (tape type identification).
There shall be two typos of reel hub diameter:
hole 3 closed: cassette with small hub:
hole 3 open: cassette with large hub.
Hole 2, hole 4 and hole 5 shall be closed and hole 6 shall be open. Other combinations are reserved for future assignment.
2.1.9 Reel
Locations of the reels, ready for rotation, are shown in figures 4 and 17. Dimensions of the reels are shown in figures 6 and 19. Heights of the reels are shown in figures 7 and 20.
The reels shall be automatically unlocked when the cassette Is inserted into the video tape recorder and/or player unit and automatically locked when the cassette is ejected from it.
The reel shall be completely released when the cassette lid Is opened 23.5 mm minimum from datum plane Z.
The reels assembled in the cassette shall be pressed by the reel spring with a specified force under the conditions specified in figures 11 and 24. The reel spring shape is specified in figure 11 for S cassettes and in figure 24 for I cassettes, and the spring force shall be 1.5 N ± 0,5 N (153 gf ± 51 gf) for S cassettes and 3.5 N ± 0.5 N (357 gf ± 51 gf) for L cassettes when pressing on a reel 2,4 mm above datum plane Z as shown in figures 11 and 24.
The force (Fl, F2) required to pull the tape out from the reel shall not exceed 0.17 N (17 gf), as specified in figures 13a and 26a,
The torque required to wind the tape shall be less than 15 mN m (152 gf cm) fo $ cassettes and less than 30 mN m (305 gf cm) for I cassettes, as specrf led in figures 13b and 26b.
2.1.10 Protecting lid
The cassette lid shall be automatically unlocked when the cassette is inserted into the video tape recorder and]or player unit and automatically locked when the cassette is ejected from it.
The unlocking lever insertion area Is specified in fIgures 8 and 21.
The lid shall be unlocked when the lid lock lever is shifted in either direction A or B, as illustrated in figures 9 and 22. The force required to unlock the lid shall be less than I N (101 gf) In the A direction or less than 1.5 N (152 91) In the B direction.
The lid shall open 29,0 mm with a force of 1,5 N (152 gf) or less as specified in figures 10 and 23.
2.2 Magnetic tape
2.2.1 Base
The base material shall be polyester or equivalent.
2.2.2 Tape width
The tape width shall be 12,650 mm ±0,005 mm.
2.2.3 Tape thickness
The tape thickness shall be from 12,5 pm to 13,8 pm.
2.2.4 Transmisslvity
Transmissivity, measured in the range of wavelength from 700 nm to 900 nm, shall be less than 5 %.
2.2.5 Offset yield strength
The offset yield strength shall be greater than 20 N.
2.2.6 Magnetic coating
The magnetic tape used shall have a coating of metal particles or equivalent, longitudinally
oriented, and having a coercivify In the range 01117 000 Aim to 133 000 Aim.
3 Helical recordings
3.1 Tape speed
The tape speed Shall be 96.7 mmis. The tape speed tolerance shall be ±0,2 %.
3.2 Record location and dimensions
Geometrical location and dimensions of the recordings on the tape and their relative positions In regard to timing relations ol the recorded signals shall be as specified in figure 27 and table 2.