1、SMPTE RECOMMENDED PRACTICE RP 36-1999 Revision of RP 36- 1994 Positioning the Headwheel and Adjacent Tape Guides for 2-in Quadruplex Video Magnetic Tape Recorders Page 1 of 3 pages 1 Scope This practice establishes the relative locations of critical elements in the path of the tape between the input
2、 and output guides for 2-in (51-mrn) quadruplex viaeo magnetic tape recorders operating at 15 inls and 7.5 ink (381 rnrnls and 190.5 mm/s). 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this practice. At the time of
3、publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this practice are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. SMPTE RP 11-1994 (RI999), Tape Vacuum Guide Conf
4、iguration and Position for Quadru- plex Video Magnetic Tape Recording SMPTE RP 16-1 993 (RI 997), Specifications of Tracking-Control Record for 2-in Quadruplex Video Magnetic Tape Recordings 3 Definitions 3.1 pole tip plane: The plane of rotation of the pole tip which records vertical sync. This pla
5、ne is perpendicular to the tape neutral plane and the reference plane. 3.2 reference line: A line which is tangent to both the input guide and the output guide and is per- pendicular to the tape neutral plane defined in 3.5. 3.3 referenceplane: A plane which passes through the reference line and is
6、perpendicular to the tape neutral plane. 3.4 tape input guide: The last guiding element encountered by the tape as it approaches the vacuum guide. 3.5 tape neutral plane: A plane which is defined to be tangent to both the input guide and the output guide and also contains the reference guide. 3.6 ta
7、pe output guide: The first guiding element encountered by the tape after it leaves the vac- uum guide. 4 Dimensions - 4.1 Primary references The tape neutral plane, the reference plane, and the pole tip plane shall be the primary references for positioning the elements described in this practice (se
8、e figure 1). 4.2 Position of tape output guide The tape output guide shall be at a distance of 7.50 in f 0.25 in (190.5 mm 16.4 rnm) from the pole tip plane (see dimension B in figure 2). The guide may be on either side of the neutral plane. 4.3 Position of tape input guide The tape input guide shal
9、l be at a distance of 7.50 in f 0.35 in (190.5 mm ? 8.9 mm) from the pole tip plane and shall be located symmetrically with respect to the Copyright 1999 by the SOCIElY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Harisdale Ave., White Plains, NY 10607 Approved April 22,1999 (914) 761-1100 RP 3
10、6-1 999 pole tip plane and tape output guide with a tolerance of 0.3 in (8 mm). (See dimension A in figure 2.) The guide may be on either side of the neutral plane. 4.4 Position of tape When undeflected by thevacuum guide, the tape shall lie in the tape neutral plane with its reference edge coincide
11、nt with the reference line, and the magnetic surface facing the axis of rotation of the pole tips. 4.5 Position of axis of rotation of pole tips The axis of rotation of the pole tips shall be parallel to the tape neutral plane and 0.905 in f 0.020 in (22.99 mm k 0.51 mm) from it (see dimension C in
12、figure 2). It shall also be parallel to the reference plane and 1 .O04 in It 0.003 in (25.50 mm f 0.08 mm) from it. guide is parallel to the reference plane and 1 .O04 in k 0.003 in (25.50 mm f 0.08 mm) from it. 4.7 Relationship among pole tip plane, axis of rotation and vacuum guide The relationshi
13、p shall be as specified in SMPTE RP 11 and SMPTE RP 16. 4.8 Tape deformation by control track head Deformation of the tape by a control track head shall be limited to 0.020 in (0.51 mm) maximum, in a direction radial from the axis of rotation of the pole tips, at a location between the pole tip plan
14、e and the tape output guide, and at a distance 0.700 in f 0.100 in (I 7.78 mm f 2.54 mm) from the pole tip plane and no more than 0.060 in (1.52 mm) from the reference edge of the tape. 4.6 Position of vacuum guide The vacuum guide shall be positioned so that the centerline of the tape when deflecte
15、d by the vacuum TAPE OUTPUT GUIOE TAPE INPUT GUIDE POLE TIP PLANE REFERENCE PLANE REFERENCE LINE Figure 1 - Relationship among tape neutral plane, reference plane, and pole tip plane Page 2 of 3 pages VIDEO HEADWHEEL (r - TAPE INPUT GUIDE - RP 36-1999 -I HEAD AXIS OF ROTATION r- 4 TAPE OUTPUT GUIDE I C I VACUUM GUIDE NEUTRAL PLANE Figure 2 - Position of tape guides and headwheel assembly Page 3 of 3 pages
