1、 D 3404583 0333259 729 Helical-scan video tape cassette system using 12.65 mm (0.5 in) magnetic tape on type VHS Part I-. VHS and compact VHS video cassette system The European Standard EN 60774-1 : 1994 has the status of a British Standard Systme de magntoscope a cassette A 1)alaydge hlicodal utili
2、sant ia tiande magntique de 12,Ii.T mm (0,s in) de forinat VIIS Partie 1 : Systme de cassette vido VHS et VHS compacte Video-BdndkdssettenSystem mit Schrgspuraufzeichnung auf Magnetband 12.135 mm (0,5 in) VHS-Format Teil 1 : VHS- und kompaktes VIIS Vido-Kassettcnsystem BS EN 60774 1 : 1994 iEC 7741
3、: 1994 BS EN 60774-1 : 1994 Cooperating organizations The European Comiiiit,tee for Electrotechnical Standardization (CENELEC), under whose supervision this European Standard was prepared, comprises the national committees of the following countries: Austria Italy Belgium Luxembourg Denmark Netherla
4、nds Finland Norway Germany Spain Greece Sweden Iceland Switzerland Ireland United Kingdom France Port Ugdl Amendments issued since publication Text affected m 3404583 OLL3261i 387 m BS EN 607741 : 1994 Contents Cooperating organizations National foreword Page Inside front cover i Foreword 2 Text of
5、EN 60774-1 3 National annex NA (informative) Committees responsible Inside back cover National annex NB (informative) Cross-references Inside back cover National foreword This Part of BS EN 60774 has been prepared under the direction of the Electronic Equipment Standards Policy Committee and is the
6、English language version of EN 60774-1 : 1994 Helical-scan video tupe cassette system u.sirq 12,65 rnm (O, 5 in) magnetic tape on type VHS - Part 1: VHS and cornpact VHS vi32 N 3.1.8 Positioning screw of take-up reel The deviation of the centre of the positioning screw head shall be less than 0.05 m
7、m from the take-up reel axis (see figure 18). Section 4: Tape characteristics of VHS and compact VHS cassette 4.1 Dimensions of the video tape 4.1 .l Magnetic tape thickness The maximum thickness of the magnetic tape, including the coating, shall be 20,O pm. See annex A for alternative thicknesses o
8、f VHS cassette and annex B for compact VHS cassette respectively. 4.1.2 Magnetic tape width The width of the magnetic tape shall be 12,65 mm f 0,Ol mm. 4.1.3 Magnetic tape length For the length of the magnetic tape of VHS cassette, see annex A, and annex B for com- pact VHS cassette. m 3404583 03332
9、70 3T m Page 9 EN 60774-1 : 1994 4.2 Magnetic tape properties 4.2.1 Type of magnetic tape The type of magnetic tape to be used shall be high-resolution magnetic tape (for example cobalt iron oxide tape). 4.2.2 Magnetic orientation The magnetic coating shall be longitudinally oriented. 4.2.3 Coercivi
10、ty The coercivity shall be approximately 50 x 1 O3 Aim. 4.3 Reference tape The reference tape numbered VRT-2 is applicable. Details are described later in annex C. 4.4 Leader tape and trailer tape 4.4.1 Automatic stop The light transmittance of the leader and trailer tape shall be at least 50 % for
11、VHS cassette and more than 70 % for compact VHS cassette respectively in order to ensure that the automatic stopping device of the machine functions properly at both ends of the magnetic tape. 4.4.2 Dimensions of the leader and trailer tape (VHS cassette) Leader and trailer tape length shall lie bet
12、ween 130 mm and 190 mm. As for exact length, which is dependent on hub size used, see annex A. Leader and trailer tape thickness shall be 40 1: pm and the width shall be 12.65 mm f 0,03 mm. 4.4.3 The leader and trailer tape length shall be 80 mm f 5 mm and 11 O mm f 5 mm respectively. The leader and
13、 trailer tape thickness shall be 20: and the width shall be 12,65 mm f 0.03 mm. Dimensions of the leader and trailer tape (compact VHS cassette) 4.4.4 Splicing The splice and the attachment of the leader and trailer tape to the hub shall be capable of resisting a force of 30 N. The splicing gap shal
14、l be less than 0.07 mm. 4.5 Amount of tape remaining The window and the upper flange of the supply reel shall be transparent to indicate the amount of tape remaining. = 3404583 OLL3231 226 TV system Standard speed mmls 525 line-60 field 33.35 625 line-50 field 23.39 Page 10 EN 607741 : 1994 Toleranc
15、es % i 0,5 i 0,s Section 5: Video cassette recorders 5.2 Drum diameter The drum diameter shall be 62,OO mm i 0,Ol mrn. NOTE - Different dimensions of drum diameter are also possible as far as the track configuration and dimensions are in accordance with figure 19 and table 2. 5.3 Tape tension The ta
16、pe tension during recording and reproducing shall be between 0.30 N and 0,45 N, measured at the entrance of the drum. 5.4 Inclined azimuth angle The gap line of video heads shall be slanted in accordance with the figure below. Video head channel 1 Video head channel 2 5.5 Track configuration and dim
17、ensions 5.5.1 Record locations The track configuration and dimensions shall be in accordance with figure 19 and table 2. 5.5.2 The switching position between the two video heads shall lie between five and eight horizontal scanning lines ahead of the front edge of the vertical synchronizing pulse. Th
18、e minimum overlap of the two video heads shall be three horizontal lines. Switching position and video signal overlap 3404583 OLL3272 Lb2 Reference white level Reference sync level Frequency deviation. white to sync Page 11 EN 60774-1 : 1994 4.4 MHz f 0.1 MHz 3,4 MHz f 0,1 MHz 1,0 MHz f 0.1 MHz 4.8
19、MHz f 0,l MHz 3.8 MHz f 0.1 MHz 1,0 MHz f 0,l MHz 5.5.3 Relations of video track and video signal field The track used for the first field of the recorded video signal is not specified. However, recorders which can distinguish between fields shall record the first field on the channel 1 track. Secti
20、on 6: Recording Characteristics 6.1 FM recording of Iminance component 6.1 .I Lo w-pass filter The luminance component of the composite vido signal shall be separated by a low-pass filter, the attenuation of which is greater than 40 dB at the chrominance sub-carrier frequency. 6.1.2 fre-emphasis and
21、 clipping The luminance signal shall be pre-emphasized and clipped prior to frequency modulation. The characteristics of the pre-emphasis network measured without the low-pass filter are shown in figure 23, and clipping levels are shown below. The level from sync tip to peak white is 100 %. White cl
22、ipping level: (160 5 ) % measured from sync tip. Dark clipping level: (40 f 10) % measured from sync tip. 6.1 -3 Modulation characteristics FM carrier frequencies corresponding to reference video levels shall be as shown in the following table 1. Table 1 - FM carrier frequency I 525 line-60 field I
23、625 line-50 field I I 6.1.4 FM high-pass filter The amplitude frequency response of the FM high-pass filter shall be in accordance with figure 22. Page 12 EN 607741 : 1994 3404583 0333273 OT m 6.1.5 Recording level The recording current shall have the optimum value at all frequencies within the enti
24、re FM carrier range, as defined in table 1, NOTE - Optimum record current is the recording current value which is necessary to obtain the maximum output signal level during playback. 6.2 NTSC Chrominance signal recordlng 6.2.1 Recording method The chrominance signal is separated from the NTSC colour
25、 video signal through a band- pass filter with a centre frequency of 338 MHz and -3 dB points at I500 kHz. The separated chrominance component shall be then down-converted so that its new carrier frequency equals 40 times the horizontal scanning rate. This recording process is illustrated in figure
26、20 and explained in 6.2.2. 6.2.2 Phase rotation of the chrominance signal The chrominance signal of channel 1 track shall be phase advanced by 90“ at every horizontal sync interval. The chrominance signal of channel 2 track shall be phase retarded by 90“ at every horizontal sync interval. Phase shif
27、t should be completed prior to the colour burst. Channel 1 and channel 2 are specified in clause 5.4. 6.2.3 Recording level The chrominance signal is recorded with the FM signal acting as bias. Its record level should be adjusted so that the playback level is 7 dB to 10 dB below the level corre- spo
28、nding to the saturation record level of this chrominance signal with the optimum FM bias current. NOTE - The saturation record level of the unmodulated chrominance carrier is reached when the play-back level no longer increases with increase in record current. 6.2.4 Colour burst amplitude doubler Th
29、e amplitude of the colour burst shall be increased by (6 f 05) dB prior to recording. 6.3 PAL chrominance signal recording 6.3.1 Recording method The chrominance signal is separated from the PAL colour video signal through a band- pass filter with a centre frequency of 4,43 MHz and -3 dB points at 1
30、500 kHz. 3404583 OLL3274 T35 Page 13 EN 607741 : 1994 The separated chrominance component shall be then down-converted so that its new carrier frequency equals 40 times the horizontal scanning rate plus 1,953 kHz (626,953 kHz). This recording process is illustrated in figure 20, and explained in 6.3
31、.2. 6.3.2 Phase rotation of the chrominance signal The chrominance signal of channel 2 track only shall be phase-retarded by 90“ at every horizontal sync interval. The channel 1 track remains at O“. Phase shift should be completed prior to the colour burst. Channel 1 and channel 2 are specified in c
32、lause 5.4. 6.3.3 Recording level The chrominance signal is recorded with the FM signal acting as bias. Its record level should be adjusted so that the playback level is 7 dB to 10 dB below the level corre- sponding to the saturation record level of this chrominance signal with the optimum FM bias cu
33、rrent. NOTE - The saturation record level of the unmodulated chrominance carrier is reached when the play-back levei no longer increases with increase in record current. 6.4 SECAM chrominance signal recording 6.4.1 Recording method The chrominance signal is separated from the SECAM colour video sign
34、al through a band- pass filter with a centre frequency of 4,32 MHz and -3 dB points at f800 kHr. The separated chrominance component shall be counted down so that the frequency of the recorded chrominance signal becomes a quarter of the input chrominance frequency. This recording process is illustra
35、ted in annex E, figure El. An alternative method of SECAM chrominance signal recording is illustrated in figure E2. 6.4.2 Recording level The chrominance signai is recorded with the FM signal acting as bias. Its record level should be adjusted so that the play-back level is 7 dB to 10 dB below the l
36、evel corre- sponding to the saturation record level of this chrominance signal with the optimum FM bias current. NOTE - The saturation record level of the unmodulated chrominance carrier is reached when the play-back level no longer increases with increase in record current. 6.5 Audio signal recordi
37、ng 6.5.1 Recording level The recorded reference audio level shall be 100 nWb/m. = 3404583 0333275 971 Page 14 EN 60774-1 : 1994 6.5.2 De-emphasis characteristics The recording and reproducing characteristics of the audio signal, as defined in section three of IEC 94-1 shall make use of the following
38、 time constants. t,: 120 ps t2: 3 180 ps 6.6 Control signai recording 6.6.1 Recording signal A positive going edge of the recorded control pulse signal shall be coincident with the start of channel 1 track scanning as shown in figure 24. Channel 1 and channel 2 video tracks are specified in clause 5
39、.4. 6.6.2 Polarity The control head pole tip nearest to the video drum assembly shall be north polarized when the control signal pulse is positive. 6.6.3 Recording current wave-form The rise time shall be less than 200 ps. Table 2 - Track configuration (see figure 19) Dimensions in millimetres A B W
40、 L P T C R D E F h 0 00 X Tape width Total video width Effective video width (180) Videotrack centre from reference edge of the tape Video track pitch Video track width Control track width Audio track width (monophonic) Audio track (channel 2) width (stereophonic-right) Audio track (channel 1) width
41、 (stereophonic-left) Audio track reference line Audio to audio track guard band width Video track angle Video track angle (tape stationary) Position of audio and control head 525 line-60 field 12,65 f 0,Ol 10,60 10,07 62 0.058 0.058 0.75 f 0,l l,o f 0,l 0,35 f 0,05 0.35 f 0.05 11.65 i 0,05 0,3 f 0.0
42、5 5“5809.9 5O5607.4 79.244 NOTE -Where tolerances are not given, the quoted values are nominal. 625 line-50 field 12,65 f 0,Ol 10,60 10,07 62 0,049 0,049 0,75 f 0.1 l,o i 0,l 0,35 f 0,05 0,35 f 0,05 1 1.65 i 0.05 0.3 f 0,05 5-5 750 3“ 5“5607.4“ 79.244 = 3404583 OLL3276 808 Page 15 EN 60774-1 : 1994
43、-y- - O .-L 5 f 0.2 c R 0.5 _+ 0.2 O o1 Note 10 O +I -0 in O U ti (D I -. +I 2 4zo 5k0.2 O +I 25I0.2 I Note 9 ZZ +I 2 =l=t- Section A-A c. O0 * N- L Seciwn E-E seai c-c Section D-D Dimensions en millimtres Pour les notes, voir page suivante I; Dimensions in millimetres For notes, see next page Figur
44、e 1 - Aspect de la cassette vido. Vue de dessus et vue latrale Appearance of videocassette. Top and side view 3404583 0113277 744 9 Page 16 EN 607741 : 1994 Notes relatives a la figure 1 NOTES 1 2 3 4 5 6 7 8 9 10 11 Zone de ltiquette suprieure. Rainure-guide A pour empcher lintroduction de la casse
45、tte dans le mauvais sens. Rainure-guide B pour empcher lintroduction de la cassette dans le mauvais sens. Patte de rupture pour empcher un effacement accidentel. Fentre pour la bobine rceptrice. Fentre pour la bobine dbitrice. Zone de ltiquette latrale. Broche de dbverrouillage pour le couvercle fro
46、ntal. Encoches pour le positionnement de la cassette. Ces tolrances comprennent un lger jeu du couvercle frontal. Ce logement est destin empcher lintroduction de la cassette dans le mauvais sens: il nest toute- fois pas obligatoire. Notes lo figure 7 NOTES 1 2 3 4 5 6 7 8 9 10 11 The top label area.
47、 Guide groove A to prevent misinsertion. Guide groove B to prevent misinsertion. Break-out lug to prevent accidental erasure. Window for take-up reel. Window for supply reel. Side label area. Unlocking pin for the front cover. Slots for positioning of the cassette. These allowances include slight pl
48、ay of the front cover. This recess is to prevent misinsertion but may not necessarily exist. 3404583 OLL3278 680 Page 17 EN 607741 : 1994 c C t U c Infbrieur o- Less than +I Secton A-A Dimensions en millimtres Pour les notes. voir page suivante Dimensions in millimetres For notes, see next page Figu
49、re 2 - Aspect de la cassette vido. Vue de dessous Appearance of videocassette. Bottom view D 3404583 OLL3279 517 W Page 18 EN 607741 : 1994 Notes relatives la figure 2 NOTES 1 Trou de rfrence. 2 3 4 5 Plan de rfrence. 6 7 8 Position du trou auxiliaire. Trou pour le capteur lumineux. Trou pour le faisceau lumineux du capteur. Trou de dverrouillage pour le frein de bobine. La planit de ces quatre plans de rfrence peut tre affecte dune erreur infrieure 0,2 mm. Rainure-guide A pour empcher lintroduction de la cassett
