CA1129089A - Apparatus for reproducing a video signal including an address signal when the video tape moves at various speeds - Google Patents
Apparatus for reproducing a video signal including an address signal when the video tape moves at various speedsInfo
- Publication number
- CA1129089A CA1129089A CA330,089A CA330089A CA1129089A CA 1129089 A CA1129089 A CA 1129089A CA 330089 A CA330089 A CA 330089A CA 1129089 A CA1129089 A CA 1129089A
- Authority
- CA
- Canada
- Prior art keywords
- vitc
- video tape
- signal
- heads
- tape
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000010363 phase shift Effects 0.000 claims description 3
- 241000283986 Lepus Species 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- FBOUIAKEJMZPQG-AWNIVKPZSA-N (1E)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pent-1-en-3-ol Chemical compound C1=NC=NN1/C(C(O)C(C)(C)C)=C/C1=CC=C(Cl)C=C1Cl FBOUIAKEJMZPQG-AWNIVKPZSA-N 0.000 description 1
- GKSPIZSKQWTXQG-UHFFFAOYSA-N (2,5-dioxopyrrolidin-1-yl) 4-[1-(pyridin-2-yldisulfanyl)ethyl]benzoate Chemical compound C=1C=C(C(=O)ON2C(CCC2=O)=O)C=CC=1C(C)SSC1=CC=CC=N1 GKSPIZSKQWTXQG-UHFFFAOYSA-N 0.000 description 1
- 241001527902 Aratus Species 0.000 description 1
- 101000860173 Myxococcus xanthus C-factor Proteins 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
- G11B27/19—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
- G11B27/28—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording
- G11B27/30—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on the same track as the main recording
- G11B27/3027—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on the same track as the main recording used signal is digitally coded
- G11B27/3036—Time code signal
- G11B27/3054—Vertical Interval Time code [VITC]
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B15/00—Driving, starting or stopping record carriers of filamentary or web form; Driving both such record carriers and heads; Guiding such record carriers or containers therefor; Control thereof; Control of operating function
- G11B15/18—Driving; Starting; Stopping; Arrangements for control or regulation thereof
- G11B15/1808—Driving of both record carrier and head
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
- G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B5/584—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on tapes
- G11B5/588—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on tapes by controlling the position of the rotating heads
Abstract
ABSTRACT OF THE DISCLOSURE
A video signal reproducing apparatus capable of reproducing parallel record tracks formed on a tape which are scanned by a rotary head and wherein track address signals are recorded on respective vertical blanking interval sections of the record tracks which can be read out and displayed even though the tape moves at various speeds comprising a detecting means for detecting when said track address signals are not being read out and including shifting means for shifting the relative position of the rotary heads relative to the tape when the output of the detecting means continues longer than a predetermined time so as to assure that the address signals will be read at varying speeds of the tape.
A video signal reproducing apparatus capable of reproducing parallel record tracks formed on a tape which are scanned by a rotary head and wherein track address signals are recorded on respective vertical blanking interval sections of the record tracks which can be read out and displayed even though the tape moves at various speeds comprising a detecting means for detecting when said track address signals are not being read out and including shifting means for shifting the relative position of the rotary heads relative to the tape when the output of the detecting means continues longer than a predetermined time so as to assure that the address signals will be read at varying speeds of the tape.
Description
l~Z90~9 ~ACI~G~OU~rlD OF T~E Ir~V~NTI~N
~ield of the Invention -The present invention relates in ~eneral to video sl~nal reproducing apparatus and in particular to improved aoparatus for assuring that the address signal recorded on video tape can be read out at various tape speeds.
Descri~tion of the Prior ~rt . . .
Video tape reproducing machines are known which include apparatus in which a pair of heads are rotated so as to read slant tracks formed on the tape as the tape is passed throu~h the machine.
SUMI~ARY C)F THE IN~7E:NTION
The present invention includes means for detecting the reproduced video signal including a rotating head arrangement which moves relative to the tape to read slant tracks recorded on the tape and further includes a video taoe code decoder for detecting the code on the tape and further includes a timer and a comparator which resoectively receives the output of the decoder and wherein the timer supplies an input to the comparator and the comparator supplies an outout to a control circuit which adjusts the phase or the speed or the relative position of the heads relative to the tape so that the various code si~nals will be correctly reproduced and detected.
Other objects, features and advantages of the invention will be readily anparent from the following descriPtion of certain preferred embodiments thereof taken in conjunction with the accompanyin~ dxawings, althou~h variations and modifications may be effectefl without departing from the spirit and scope of the novel concepts of the disclosure and in which:
ll~,9C~
BRIEE DESCRIPTION OF T~E DR~ GS
Figures lA through lD illustrate the VITC signal, Figure 2 is a partial plan view of the video tape illustrating various slant tracks formed thereon-Pigure 3 comprises a block diagram of a frame numberdisplay ap~aratus according to one e~bodiment of the invention;
and Figures 4A through 4D il]ustrate waveforms o,f various signals at different points in ~igure 3.
DF,SCRIPTION OF THF, PREPERRED E~BOnIME~lTS
This invention relates to a video signal reproducing apparatus in which when parallel record tracks formed on a tape are scanned by a pair of rotary heads, the track address signals which are recorded on respective vertical blanking interval sections of the parallel tracks can be read out by the rotary head and provided to a display means where they are displayed.
mhe prior art devices have had video signals recorded on magnetic tape in which time codes functioning as indexes for the video signal are recorded on the magnetic ta~e which could be used, for example, ~or electronic editing.
One example of such sound tracks or cue tracks recorded on magnetic tape is the so-called "SMPTE time code". Also, there is a VITC signal which is used as a time code and which this invention relates to.
The VITC signal is recorded on the magnetic tape in a manner which is different from the SMPTE time code. The VITC
signal is mixed with the video signal and recorded in the video si~nal track on the magnetic tape. It is continuously inserted, for example, in one horizontal interval section after a post group equalizing pulse interval section in a vertical blanking time section. A one horizontal interval (lH) is illustrated in Eigure .
I
1~9 1~. In Figure 1~, ~ID represents a horizontal synchronizin~
signal and BS represents a burst signal. A time starting signal 1.5~ ~s prior to the front edqe of the horizontal synchronizing pulse ~D until a second time which is 9.56~ts after the front ed~e of the horizontal signal HD defines one horizontal blan~ing interval. A VITC signal for a Particular fi.eld is inserted in a video interval ~ ich is shorter by an amount equal to the horizontal blankina interval than the interval 1~.
The bit frequency fb of the VITC signal is determined as follows~
f = a 5 5 f h , 1 - 7 9 [ 1'1~ z ]
where fh represents the horizontal scanning fre~uency. Thus, the interval of lH corresponds to 113. 75 bits. The VITC signal of 90 bits is recorded on one record track. The code arrangement of the VITC signal is illustrated in Figure lB. Synchronizing bit portions each having two bits are shown by oblique lines and are arranged at intervals of ten bits. For example ! in Figure lB, the synchroni~ina bit portions are between bits 0 and 2, 10 and 12, 20 and 22, 30 and 32, 40 and 42, 50 and 52, 60 and 62, 70 and 72, and 30 and 82. Predetermined bit values (1,0) are given to the synchronizing bits. 4 bits after the first synchronizing bits
~ield of the Invention -The present invention relates in ~eneral to video sl~nal reproducing apparatus and in particular to improved aoparatus for assuring that the address signal recorded on video tape can be read out at various tape speeds.
Descri~tion of the Prior ~rt . . .
Video tape reproducing machines are known which include apparatus in which a pair of heads are rotated so as to read slant tracks formed on the tape as the tape is passed throu~h the machine.
SUMI~ARY C)F THE IN~7E:NTION
The present invention includes means for detecting the reproduced video signal including a rotating head arrangement which moves relative to the tape to read slant tracks recorded on the tape and further includes a video taoe code decoder for detecting the code on the tape and further includes a timer and a comparator which resoectively receives the output of the decoder and wherein the timer supplies an input to the comparator and the comparator supplies an outout to a control circuit which adjusts the phase or the speed or the relative position of the heads relative to the tape so that the various code si~nals will be correctly reproduced and detected.
Other objects, features and advantages of the invention will be readily anparent from the following descriPtion of certain preferred embodiments thereof taken in conjunction with the accompanyin~ dxawings, althou~h variations and modifications may be effectefl without departing from the spirit and scope of the novel concepts of the disclosure and in which:
ll~,9C~
BRIEE DESCRIPTION OF T~E DR~ GS
Figures lA through lD illustrate the VITC signal, Figure 2 is a partial plan view of the video tape illustrating various slant tracks formed thereon-Pigure 3 comprises a block diagram of a frame numberdisplay ap~aratus according to one e~bodiment of the invention;
and Figures 4A through 4D il]ustrate waveforms o,f various signals at different points in ~igure 3.
DF,SCRIPTION OF THF, PREPERRED E~BOnIME~lTS
This invention relates to a video signal reproducing apparatus in which when parallel record tracks formed on a tape are scanned by a pair of rotary heads, the track address signals which are recorded on respective vertical blanking interval sections of the parallel tracks can be read out by the rotary head and provided to a display means where they are displayed.
mhe prior art devices have had video signals recorded on magnetic tape in which time codes functioning as indexes for the video signal are recorded on the magnetic ta~e which could be used, for example, ~or electronic editing.
One example of such sound tracks or cue tracks recorded on magnetic tape is the so-called "SMPTE time code". Also, there is a VITC signal which is used as a time code and which this invention relates to.
The VITC signal is recorded on the magnetic tape in a manner which is different from the SMPTE time code. The VITC
signal is mixed with the video signal and recorded in the video si~nal track on the magnetic tape. It is continuously inserted, for example, in one horizontal interval section after a post group equalizing pulse interval section in a vertical blanking time section. A one horizontal interval (lH) is illustrated in Eigure .
I
1~9 1~. In Figure 1~, ~ID represents a horizontal synchronizin~
signal and BS represents a burst signal. A time starting signal 1.5~ ~s prior to the front edqe of the horizontal synchronizing pulse ~D until a second time which is 9.56~ts after the front ed~e of the horizontal signal HD defines one horizontal blan~ing interval. A VITC signal for a Particular fi.eld is inserted in a video interval ~ ich is shorter by an amount equal to the horizontal blankina interval than the interval 1~.
The bit frequency fb of the VITC signal is determined as follows~
f = a 5 5 f h , 1 - 7 9 [ 1'1~ z ]
where fh represents the horizontal scanning fre~uency. Thus, the interval of lH corresponds to 113. 75 bits. The VITC signal of 90 bits is recorded on one record track. The code arrangement of the VITC signal is illustrated in Figure lB. Synchronizing bit portions each having two bits are shown by oblique lines and are arranged at intervals of ten bits. For example ! in Figure lB, the synchroni~ina bit portions are between bits 0 and 2, 10 and 12, 20 and 22, 30 and 32, 40 and 42, 50 and 52, 60 and 62, 70 and 72, and 30 and 82. Predetermined bit values (1,0) are given to the synchronizing bits. 4 bits after the first synchronizing bits
2 bits are allocated to the frame code Fl. The`frame code Fl representS a number of single di~its of the fra~e address such as for example (0, 1, 2---9). The frame code F2 represents a single digit of the 10 Figures related to the frame address as, for exam~le, (10, 20, 30---) and F2 is located after bits 10-12.
One bit after the frame code F~ ls selected as a drop frame bit D. ~he next bit after the drop frame bit D is desianated a field code FL. A value of "0" is given to the field code FL
for the first field of one frame, and another value of "1" is allocated to the field code ~l, for the second fi.eld of the 29~3~39 number l frame. Two groups of 4 bits after the third and fourth synchronizing bit portions are used for second codes Sl and S2 res~ectively. Two portions of 4 bits after the fi~th and sixth synchronizing bit portions are used for minute codes Ml and ~2 respectively and these codes indicate the time and minutes for the particular address. Two portions of 4 bits after the seventh and eighth synchroni~ing bit portions are allocated for the hour codes ~l and ~2' respectively. In the minute and hour codes first portions ~1l and Hl designate the units of minutes and hours respectively~ and the second portions M2 and 112 designate the number of tens of the minutes and hours, respectively.
Eight groupS of 4 bits each are allocated to user-bit portions designated BGl through BG~ in Fiaure lB. An error detecting code indicated for e~ample as CRC (Cyclic ~edundancy Check) code of 7 bits follows the last of the synchronizin~ bit portions between bit 82 and bit 89 as sho~n in Figure lB.
Fi~ure lC illustrates a read-out of the binary numbers associated t~ith the various codes identified above for a particular embodiment of the VITC signal. Figure lD illustrates waveforms associated with the example given in Figure lC and the particular embodiment the time codes read ~3 hours 59 minutes 59 seconds 29 frame. The values of the drop frame bit D is."l" and the ~ield code FL is "0". As contrasted to the SMPT~ time code, the VITC
signal is recorded on the video track and it can b~ nositively read out even in slow reproduction mode and still reproduction mode.
Figure 2 ls a plan view of a part of a magnetic tape 60 on which the VITC si~nals are recorded. The pluralit,v of parallel/record trac]~s T are formed at predetermined intervals and each re~resent one field on the magnetic tape.
A guard band 2 is formed between two adjacent record tracks T.
The VITC signal is recorded in the vertical blanking interval 1129~
~ection of each of the xecord tracks T. In the video tape recorder-reproducer which reads out the VITC signal and displays the frame number during reproduction of video signals from the magnetic tape 1, at times the magnetic tane 1 will be in the fast forward transport mode or in the rewind mode so as to position the tape to a particular nortion for reference or electronic editing. I~hen this occurs, if the tape running speed is set to a multiple of or nearlv a multiple of the normal record or reproduction tape running speeds, it is possible that the rotary head will not scan the record portion of the VITC signal 3 but will scan the guard band 3 between the recorded signals or record track.s T and in this event, the VITC signal cannot be read from the tape.
It is an object of the present invention to solve this problem. According to the invention, even if the tape running s~eed differs from the normal record or reproduction tape running speed, a track address signal can be accurately read from the tape.
Figure 3 illustrates one embodiment of the invention for accomplishin~ these results.
Figure 3 illustrates a video tape recorder VTR and the tape 60 passes around an upper drum 61 and a lower drum 62 where it is scanned by a pair of magnetic heads 63 and 64 which produce si~nals that are fed to amplifiers 76 and 77. Switching means 78 is connected to the amplifiers 76 and 77 and provides an output video signal on lead 79. The reproduced video signal a from lead 79 is also supplied to a VITC signal separating circuit 12 which is a gate circuit operatin~ at a predetermined timing, and which receives a gate signal on lead ~1. A separated VI~C
signal b is applied from the output of the separator 12 to a VITC decoder 13 which supplies an output to a display unit 17 which indicates the decoded address information which is detected - ~:
....
9~
such as the seconds, minutes, hours and frame or rield of the VI L C information.
~ 7hen the relationship between the record track T and the head scanning path i5 as shown in solid line in ~igure 2, the VITC signal will be properly reacl out and indicated by the indicator 17. On the other hand, if the path of the scanning, heads 63 and 6~ corresponds to the dotted line position relative to the tape shown in ~igure ~, the proper VITC signal will not be correctly read from the taPe by the heads, T~hen this condition exists, an error signal Sl indicated in ~igure 4A will be formed in the ~IITC deco~ler or read out circuit 13. The error signal S
may be forme~ by detecting the C~C code contained in the VITC
siqnal. Alternative]y, when the head scanning path is areatly deflected from the VITC recorded portion, the error signal S1 ma~
be formed b~ detecting the greatl~ deflected head scanning path.
Alternatively, the error signal S1 may be for~ed b~ detecting the level of the reproducea F~ ~lave when the level of the reproduced FM wa~e is lower than a predetermined level.
The error signal S1 is supplied to a comparator 15 from the decoder 13 and is also supplied to a timer 14, The timer, for example, may be a monostable multivibrator which produces a high level signal which continues for,the predetermined time starting in synchronization with the leading edge of the error signal Sl. A signal ~S2 is illustrated in ~igure 4B which continues at a high level for a time interval t which can be, for exam21e, several times as lonq as the vertical scanning period and which starts from the leading edqe o.f the error signal S1 as illustrated in Figures 4A and 4B, The signal S2 from the timer 14 is supplied to the co~parator which produces an output ,, signal S3 shown in Figure 4C which is high when either of the signals Sl or S~ have dropped -to zero and the other signal is still high. In other words, the signal S3 indicates the additional 9~
length that the signal Sl has relative to the timing output signal S2.
~ control or driver circuit 16 receives the out?ut signal S3 ~n~ produces a control siqnal c which can be used to shift the rotational speed of the rotary drum of the VTR based on the output signal S3. The control signal c mav be used as a signal to shift the phase of the reference pulse of 60 cycles that is applied to a reference terminal ~3 and to a ~hase shift device 74 which also receives the control signal c from the control circuit 16. A ~hase comparator 73 receives the output of the phase shift circuit 74 as ~Jell as an input from an amplifier 72 which receives an input from a detector 71 that picks up a magnetic reference siqnal from a magnetic element 69 on the shat 66 on the output of the motor 67 which drives the drums 61 and 62. The phase comparator 73 produces an output signal which is supplied to the motor 67 throuah a low pass filter 6~ to cause the motor 67 to drive the drums at a speed such that the VITC signal can be properlv read.
In other words, when the signals Sl and S2 are not of the same lenqth and an error signal S3 is produced as illustrated Figure4D, the motor fi7 will be driven at a proper sDeed 90 as to cause the scanning heads 63 and 64 to coincide with the tracks T on the video tape 60 so that the address signals can be read from the tape.
Instead of controlling the rotarv drum motor 67, alternative methods of assuring coincidence between the tracks T
and the reading heads 63 and 64 can be utilized with the error signal S3. For example, in VTR s,vstems in which the capstan is servo controlled, the rotary phase of the ca~stan motor may be varied to shift the positional relationship between the magnetic tane in the rotary head. Thus, the control signal c would be supplied to the capstan motor in that embodiment.
:`:
.. . . .. . . ..
1~2~8~
Alternatively, if a brake assembly is provided for speed control of the drum or capstan, the control signal C may be temporarily supplied to the brake assembly to correct the scanning path of the rotary head as determined by the error signal.
Alternatively, when a reel motor is utilized and servo controlled for fast forward operation and rewind operations, the reel motor speed may be controlled with the control signal c to correct the scanning path of the rotary head.
An alternative apparatus for correcting the scanning of the rotary head can comprise means for changing the running path of the magnetic tape about the drums 61 and 62 wherein, for example, the height of the tape guide 94 is controlled by a solenoid 90 which has a tapered plunger 92 so as to move the tape guide axially as shown by an arrow h in Fig. 3 thus causing the path of tape 60 to vary relative to the drums 60 and 62. Figure 3 illustrates an input terminal 93 to which the control signal from the control circuit or driver 16 could be supplied for this embodiment.
The situation has been described in which the guard band 2 is formed between two adjacent record trac~s. In a VTR in which the rotary heads for recording/reproducing signals are different from each other in azimuth so as to decrease cross-talk components between the adjacent record tracks T and guard bands are not formed between the adjacent record tracks T, there is the danger that the rotary heads will scan the record tracks T with a diferent azimuths ~, and therefore the VITC signal might not be correctly reproduced.
Hbwever, according to the present invention, positional relationship il between the magnetic tape and the rotary head is changed with the control signal c and the frarne number can always be read and displayed.
Thus, in the present invention, at any time in which the track address signals are not correctly read out, a control signal will be obtained so as to change the positional relationship _ 9 _ . .
9 ~ ~33 between the ~agnetic tape ancl the rotary head and such control signal is utilized for adjusting the relationship between the readin~ heads and the ta~e such that the co.rrect address signal can be read from the tape and displayed.on the display device.
Thus, the invention assures that the track adclress signal will always be available and indicated on the indicator 17.
Althou~h the invention has been described with respect to preferred embodiments thereof, it is not to be so limited as changes and modifications may be ~ade which are within the full intended scope as defined by the ap~ended claims.
One bit after the frame code F~ ls selected as a drop frame bit D. ~he next bit after the drop frame bit D is desianated a field code FL. A value of "0" is given to the field code FL
for the first field of one frame, and another value of "1" is allocated to the field code ~l, for the second fi.eld of the 29~3~39 number l frame. Two groups of 4 bits after the third and fourth synchronizing bit portions are used for second codes Sl and S2 res~ectively. Two portions of 4 bits after the fi~th and sixth synchronizing bit portions are used for minute codes Ml and ~2 respectively and these codes indicate the time and minutes for the particular address. Two portions of 4 bits after the seventh and eighth synchroni~ing bit portions are allocated for the hour codes ~l and ~2' respectively. In the minute and hour codes first portions ~1l and Hl designate the units of minutes and hours respectively~ and the second portions M2 and 112 designate the number of tens of the minutes and hours, respectively.
Eight groupS of 4 bits each are allocated to user-bit portions designated BGl through BG~ in Fiaure lB. An error detecting code indicated for e~ample as CRC (Cyclic ~edundancy Check) code of 7 bits follows the last of the synchronizin~ bit portions between bit 82 and bit 89 as sho~n in Figure lB.
Fi~ure lC illustrates a read-out of the binary numbers associated t~ith the various codes identified above for a particular embodiment of the VITC signal. Figure lD illustrates waveforms associated with the example given in Figure lC and the particular embodiment the time codes read ~3 hours 59 minutes 59 seconds 29 frame. The values of the drop frame bit D is."l" and the ~ield code FL is "0". As contrasted to the SMPT~ time code, the VITC
signal is recorded on the video track and it can b~ nositively read out even in slow reproduction mode and still reproduction mode.
Figure 2 ls a plan view of a part of a magnetic tape 60 on which the VITC si~nals are recorded. The pluralit,v of parallel/record trac]~s T are formed at predetermined intervals and each re~resent one field on the magnetic tape.
A guard band 2 is formed between two adjacent record tracks T.
The VITC signal is recorded in the vertical blanking interval 1129~
~ection of each of the xecord tracks T. In the video tape recorder-reproducer which reads out the VITC signal and displays the frame number during reproduction of video signals from the magnetic tape 1, at times the magnetic tane 1 will be in the fast forward transport mode or in the rewind mode so as to position the tape to a particular nortion for reference or electronic editing. I~hen this occurs, if the tape running speed is set to a multiple of or nearlv a multiple of the normal record or reproduction tape running speeds, it is possible that the rotary head will not scan the record portion of the VITC signal 3 but will scan the guard band 3 between the recorded signals or record track.s T and in this event, the VITC signal cannot be read from the tape.
It is an object of the present invention to solve this problem. According to the invention, even if the tape running s~eed differs from the normal record or reproduction tape running speed, a track address signal can be accurately read from the tape.
Figure 3 illustrates one embodiment of the invention for accomplishin~ these results.
Figure 3 illustrates a video tape recorder VTR and the tape 60 passes around an upper drum 61 and a lower drum 62 where it is scanned by a pair of magnetic heads 63 and 64 which produce si~nals that are fed to amplifiers 76 and 77. Switching means 78 is connected to the amplifiers 76 and 77 and provides an output video signal on lead 79. The reproduced video signal a from lead 79 is also supplied to a VITC signal separating circuit 12 which is a gate circuit operatin~ at a predetermined timing, and which receives a gate signal on lead ~1. A separated VI~C
signal b is applied from the output of the separator 12 to a VITC decoder 13 which supplies an output to a display unit 17 which indicates the decoded address information which is detected - ~:
....
9~
such as the seconds, minutes, hours and frame or rield of the VI L C information.
~ 7hen the relationship between the record track T and the head scanning path i5 as shown in solid line in ~igure 2, the VITC signal will be properly reacl out and indicated by the indicator 17. On the other hand, if the path of the scanning, heads 63 and 6~ corresponds to the dotted line position relative to the tape shown in ~igure ~, the proper VITC signal will not be correctly read from the taPe by the heads, T~hen this condition exists, an error signal Sl indicated in ~igure 4A will be formed in the ~IITC deco~ler or read out circuit 13. The error signal S
may be forme~ by detecting the C~C code contained in the VITC
siqnal. Alternative]y, when the head scanning path is areatly deflected from the VITC recorded portion, the error signal S1 ma~
be formed b~ detecting the greatl~ deflected head scanning path.
Alternatively, the error signal S1 may be for~ed b~ detecting the level of the reproducea F~ ~lave when the level of the reproduced FM wa~e is lower than a predetermined level.
The error signal S1 is supplied to a comparator 15 from the decoder 13 and is also supplied to a timer 14, The timer, for example, may be a monostable multivibrator which produces a high level signal which continues for,the predetermined time starting in synchronization with the leading edge of the error signal Sl. A signal ~S2 is illustrated in ~igure 4B which continues at a high level for a time interval t which can be, for exam21e, several times as lonq as the vertical scanning period and which starts from the leading edqe o.f the error signal S1 as illustrated in Figures 4A and 4B, The signal S2 from the timer 14 is supplied to the co~parator which produces an output ,, signal S3 shown in Figure 4C which is high when either of the signals Sl or S~ have dropped -to zero and the other signal is still high. In other words, the signal S3 indicates the additional 9~
length that the signal Sl has relative to the timing output signal S2.
~ control or driver circuit 16 receives the out?ut signal S3 ~n~ produces a control siqnal c which can be used to shift the rotational speed of the rotary drum of the VTR based on the output signal S3. The control signal c mav be used as a signal to shift the phase of the reference pulse of 60 cycles that is applied to a reference terminal ~3 and to a ~hase shift device 74 which also receives the control signal c from the control circuit 16. A ~hase comparator 73 receives the output of the phase shift circuit 74 as ~Jell as an input from an amplifier 72 which receives an input from a detector 71 that picks up a magnetic reference siqnal from a magnetic element 69 on the shat 66 on the output of the motor 67 which drives the drums 61 and 62. The phase comparator 73 produces an output signal which is supplied to the motor 67 throuah a low pass filter 6~ to cause the motor 67 to drive the drums at a speed such that the VITC signal can be properlv read.
In other words, when the signals Sl and S2 are not of the same lenqth and an error signal S3 is produced as illustrated Figure4D, the motor fi7 will be driven at a proper sDeed 90 as to cause the scanning heads 63 and 64 to coincide with the tracks T on the video tape 60 so that the address signals can be read from the tape.
Instead of controlling the rotarv drum motor 67, alternative methods of assuring coincidence between the tracks T
and the reading heads 63 and 64 can be utilized with the error signal S3. For example, in VTR s,vstems in which the capstan is servo controlled, the rotary phase of the ca~stan motor may be varied to shift the positional relationship between the magnetic tane in the rotary head. Thus, the control signal c would be supplied to the capstan motor in that embodiment.
:`:
.. . . .. . . ..
1~2~8~
Alternatively, if a brake assembly is provided for speed control of the drum or capstan, the control signal C may be temporarily supplied to the brake assembly to correct the scanning path of the rotary head as determined by the error signal.
Alternatively, when a reel motor is utilized and servo controlled for fast forward operation and rewind operations, the reel motor speed may be controlled with the control signal c to correct the scanning path of the rotary head.
An alternative apparatus for correcting the scanning of the rotary head can comprise means for changing the running path of the magnetic tape about the drums 61 and 62 wherein, for example, the height of the tape guide 94 is controlled by a solenoid 90 which has a tapered plunger 92 so as to move the tape guide axially as shown by an arrow h in Fig. 3 thus causing the path of tape 60 to vary relative to the drums 60 and 62. Figure 3 illustrates an input terminal 93 to which the control signal from the control circuit or driver 16 could be supplied for this embodiment.
The situation has been described in which the guard band 2 is formed between two adjacent record trac~s. In a VTR in which the rotary heads for recording/reproducing signals are different from each other in azimuth so as to decrease cross-talk components between the adjacent record tracks T and guard bands are not formed between the adjacent record tracks T, there is the danger that the rotary heads will scan the record tracks T with a diferent azimuths ~, and therefore the VITC signal might not be correctly reproduced.
Hbwever, according to the present invention, positional relationship il between the magnetic tape and the rotary head is changed with the control signal c and the frarne number can always be read and displayed.
Thus, in the present invention, at any time in which the track address signals are not correctly read out, a control signal will be obtained so as to change the positional relationship _ 9 _ . .
9 ~ ~33 between the ~agnetic tape ancl the rotary head and such control signal is utilized for adjusting the relationship between the readin~ heads and the ta~e such that the co.rrect address signal can be read from the tape and displayed.on the display device.
Thus, the invention assures that the track adclress signal will always be available and indicated on the indicator 17.
Althou~h the invention has been described with respect to preferred embodiments thereof, it is not to be so limited as changes and modifications may be ~ade which are within the full intended scope as defined by the ap~ended claims.
Claims (6)
1. Apparatus for correctly reading VITC signals on magnetic video tape with a video tape recorder reproducer having rotating drums and scanning heads and motor means for driving said heads comprising, a VITC separator receiving the detected signals from said scanning heads and separating the address signals, a VITC decoder receiving the output of said VITC
separator and decoding the various address signals, an indicator connected to said VITC decoder and indicating the various addresses such as hours, minutes, seconds and frame or field, a timer receiving an input from said VITC decoder, a comparator receiving inputs from said timer and said VITC decoder and producing an output signal indicative of the synchronization error between said video tape and said scanning heads, and synchronization correction means connected to the output of said comparator to assure synchronization between said video tape and said scanning heads.
separator and decoding the various address signals, an indicator connected to said VITC decoder and indicating the various addresses such as hours, minutes, seconds and frame or field, a timer receiving an input from said VITC decoder, a comparator receiving inputs from said timer and said VITC decoder and producing an output signal indicative of the synchronization error between said video tape and said scanning heads, and synchronization correction means connected to the output of said comparator to assure synchronization between said video tape and said scanning heads.
2. Apparatus according to claim 1 wherein said synchro-ization correction means supplies an input to said motor means for driving said heads.
3. Apparatus according to claim 2 wherein said synchronization circuit includes a control circuit receiving the output of said comparator, a phase shift circuit receiving a reference signal and the output of said control circuit, means detecting the rotational speed of said motor means for driving said heads, a phase comparator receiving the outputs of said phase shift circuit and said means detecting the rotational speed of said motor means and producing an output signal which is supplied to said motor means to synchronize it.
4. Apparatus according to claim 3 further including a low pass filter connected between said motor means and said phase comparator.
5. Apparatus according to claim 1 wherein said synchronization correction means includes means for axially moving said video tape relative to said rotating drums and the output of said comparator connected to said means for axially moving said video tape.
6. Apparatus according to claim 1 wherein said timer produces an output signal which has a length in time indicative of a synchronization between said heads and said video tape.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7403778A JPS551724A (en) | 1978-06-19 | 1978-06-19 | Video signal reproducing unit |
| JP74037/78 | 1978-06-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1129089A true CA1129089A (en) | 1982-08-03 |
Family
ID=13535549
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA330,089A Expired CA1129089A (en) | 1978-06-19 | 1979-06-19 | Apparatus for reproducing a video signal including an address signal when the video tape moves at various speeds |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US4282552A (en) |
| JP (1) | JPS551724A (en) |
| AT (1) | AT384701B (en) |
| AU (1) | AU522945B2 (en) |
| CA (1) | CA1129089A (en) |
| DE (1) | DE2924696A1 (en) |
| FR (1) | FR2430700A1 (en) |
| GB (1) | GB2023309B (en) |
| NL (1) | NL7904673A (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS581829A (en) * | 1981-05-06 | 1983-01-07 | Sony Corp | Video tape recorder |
| JPS5827485A (en) * | 1981-08-10 | 1983-02-18 | Matsushita Electric Ind Co Ltd | Magnetic recorder and reproducer |
| EP0337582B1 (en) * | 1982-09-17 | 1994-09-14 | Ampex Systems Corporation | Video tape recorder servo system having high speed control track lock capability |
| US4516164A (en) * | 1982-10-21 | 1985-05-07 | Stypher Corporation | Apparatus for decoding video address code signals |
| JPS59217254A (en) * | 1983-05-23 | 1984-12-07 | Nec Corp | Phase modifying device of vtr |
| FR2553223B1 (en) * | 1983-10-11 | 1985-11-08 | Thomson Csf | MAGNETOPHONE ALLOWING THE READING OF A TIME CODE Whatever the speed of the magnetic tape |
| US4626936A (en) * | 1984-04-30 | 1986-12-02 | Sansui Electric Co., Ltd. | Relative velocity control device for magnetic recording and reproducing apparatus |
| FR2571575B1 (en) * | 1984-10-08 | 1989-08-18 | Enertec | APPARATUS FOR RECORDING AND READING INFORMATION ON A MAGNETIC TAPE |
| US4630142A (en) * | 1984-11-02 | 1986-12-16 | Sony Corporation | Apparatus for reproducing a digital signal |
| AU590236B2 (en) * | 1984-12-21 | 1989-11-02 | Sony Corporation | Communication system for video information apparatus |
| JPS61172238A (en) * | 1985-01-26 | 1986-08-02 | Toshiba Corp | Automatic program search device of video tape recorder |
| JPH0748292B2 (en) * | 1987-04-24 | 1995-05-24 | パイオニア株式会社 | NTSC system video format signal recording device |
| JP2733526B2 (en) * | 1988-11-25 | 1998-03-30 | ソニー株式会社 | Video signal playback device |
| EP0448011B1 (en) * | 1990-03-19 | 1997-11-12 | Canon Kabushiki Kaisha | Still image reproducing apparatus |
| JPH0536254A (en) * | 1991-11-20 | 1993-02-12 | Hitachi Ltd | Retrieval device for magnetic recording and reproducing device |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1201477A (en) * | 1966-11-17 | 1970-08-05 | Matsushita Electric Ind Co Ltd | Rotation control device |
| DE1762475A1 (en) * | 1968-06-22 | 1970-06-18 | Telefunken Patent | Arrangement for phase-accurate speed control of a rotating shaft |
| JPS4919006B1 (en) * | 1968-09-14 | 1974-05-14 | ||
| US3887941A (en) * | 1972-09-01 | 1975-06-03 | Int Video Corp | Synchronizing pulse processor for a video tape recorder |
| US4127881A (en) * | 1975-10-21 | 1978-11-28 | Matsushita Electric Industrial Co., Ltd. | Tracking control system for magnetic video recording and reproducing system |
| US4163262A (en) * | 1976-01-02 | 1979-07-31 | Americal Telephone and Telegraph | Helical video tape recorder arrangement suitable for high quality editing |
| AT346089B (en) * | 1976-07-30 | 1978-10-25 | Philips Nv | PLAYBACK DEVICE |
| US4134130A (en) * | 1976-07-30 | 1979-01-09 | Sony Corporation | Method and apparatus of inserting an address signal in a video signal |
| US4044388A (en) * | 1976-10-05 | 1977-08-23 | Eastman Kodak Company | Interactive servo control system for use with a rotating-head magnetic tape player |
-
1978
- 1978-06-19 JP JP7403778A patent/JPS551724A/en active Granted
-
1979
- 1979-06-13 AU AU48032/79A patent/AU522945B2/en not_active Expired
- 1979-06-14 NL NL7904673A patent/NL7904673A/en not_active Application Discontinuation
- 1979-06-15 AT AT0425779A patent/AT384701B/en not_active IP Right Cessation
- 1979-06-18 US US06/049,546 patent/US4282552A/en not_active Expired - Lifetime
- 1979-06-18 GB GB7921144A patent/GB2023309B/en not_active Expired
- 1979-06-19 FR FR7915724A patent/FR2430700A1/en active Granted
- 1979-06-19 CA CA330,089A patent/CA1129089A/en not_active Expired
- 1979-06-19 DE DE19792924696 patent/DE2924696A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6226083B2 (en) | 1987-06-06 |
| FR2430700A1 (en) | 1980-02-01 |
| JPS551724A (en) | 1980-01-08 |
| AU522945B2 (en) | 1982-07-01 |
| GB2023309B (en) | 1982-10-27 |
| GB2023309A (en) | 1979-12-28 |
| ATA425779A (en) | 1987-05-15 |
| FR2430700B1 (en) | 1984-10-19 |
| DE2924696C2 (en) | 1988-03-10 |
| NL7904673A (en) | 1979-12-21 |
| DE2924696A1 (en) | 1980-01-03 |
| US4282552A (en) | 1981-08-04 |
| AT384701B (en) | 1987-12-28 |
| AU4803279A (en) | 1980-01-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1129089A (en) | Apparatus for reproducing a video signal including an address signal when the video tape moves at various speeds | |
| US4134130A (en) | Method and apparatus of inserting an address signal in a video signal | |
| US4193098A (en) | Segmented video playback apparatus with ancillary recording medium | |
| US4290087A (en) | Coarse and fine control of segmented video playback apparatus with ancillary recording medium | |
| US5057949A (en) | Digital magnetic reproducing apparatus with variable tape speed | |
| US4533963A (en) | Video tape recorder for re-recording audio signals | |
| US4287539A (en) | Segmented video recording with segment identification codes | |
| US4490752A (en) | Rotary recording medium having a selectively reproducible continuous stream of audio signals recorded thereon and reproducing apparatus therefor | |
| US5426538A (en) | Recording and/or reproducing apparatus with means for establishing an after-recording area | |
| US4920435A (en) | Magnetic recording and reproducing device with improved track servo | |
| EP0209151A2 (en) | Apparatus for recording and/or reproducing an information signal | |
| US5223987A (en) | Method and apparatus for reproducing at a selected speed video signals recorded on magnetic tape | |
| KR960005942B1 (en) | Magnetic recording/reproducing apparatus using segment recording system | |
| US5490017A (en) | Signal reproducing apparatus | |
| US5825971A (en) | Magnetic head replacement structure in helical scan magnetic recording and reproducing apparatus and method thereof | |
| US4300171A (en) | Magnetic recording medium direction sensing | |
| CA1307586C (en) | Apparatus for reproducing a digital signal | |
| US5648879A (en) | Method of and apparatus for controlling the phase of a video signal | |
| US5235471A (en) | Method of converting the data rate of a data signal | |
| US5461519A (en) | Recording and reproducing apparatus with helical scan tracking | |
| US6026214A (en) | Digital video recording apparatus and method | |
| EP0768661A2 (en) | Reproduction device | |
| EP0291954A2 (en) | Apparatus for reproducing video signals | |
| JP3237439B2 (en) | Control track recording method | |
| US6151440A (en) | Arrangement for segment-by-segment recording of information signals on an intermittently drivable magnetic tape |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |