Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROU~ID OF THE INVENTION
Field of the Invention
This invention relates to a magnetic recording and
reproducing device in which one of a recording head and a
recording medium is intermittently transported relatively to the
other in forward and backward directions to form record tracks
on which a video signal is recorded and from which the video
signal is reproduced.
Description of the Prior Art
A video disc recorder (VDR) is known which has two
rotational magnetic discs, respectively, having magnetic
surfaces on both sides and four magnetic heads. Each of the
magnetic heads is moved intermittently in the radial direction
to form concentric circular record tracks spaced by a predeter-
mined length from each other for recording a video signal and
reproducing it. Each of the magnetic heads effects operations
of erasing of record track, recording, reproducing and inter-
mittent movement in order. The four heads operate at different
timings in relation to the four operations. As the recording and
reproducing operation of this device is carried out through the
magnetic head stopped during ~he operations, no guard band noise
occurs on the reproduction picture in a slow reproduction mode,
still reproduction mode and reverse reproduction mode in which
the rotational speeds of the magnetic disc are different. In
such VDR, a reproduced picture of high quality can be obtained.
In the VDR, however, there are problems that the magnetic
disc is relatively expensive and the life time of its magnetic
surface is relatively short. Further, it takes about four
seconds to find out the top or initiation of recorded scene
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for reproduction, since a pulse motor is used for the inter-
mittent transportation of the magnetic head. That is incon-
venient for practical use of such VDR. Further, as operation
for finding the top is carried out by watching the reproduced
picture, it further takes a great deal of time before repro-
duction starts.
On the other hand, a VTR is known in which the position
of a rotary magnetic head is controlled transversely to the
scanning direction thereof in accordance with reducing tape
speed for obtaining a reproduction picture containing no guard
band noise. However, since some phase error is produced in the
reproduced signal by controlling the position of the head, it is
difficult in such VTR to obtain a reproduced picture of high
quality.
BRIEF SUMMARY AND OBJECTS OF THE I~VENTION
The present invention relates to a magneti.c recording
and reproducing device employing two magnetic tapes which are
intermittently transported in forward and backward directions
to form record tracks by a head on which a video signal is
recorded and from which the video signal is reproduced. Means
is provided which includes an identification code recording and
reproducing means to record and reproduce an identification
code on or from a part of each record track with the video signal
` for identifying each of the record tracks. Memory means is
included to memorize the identification code in accordance
with the operation of a first operating means to be employed
in the recording operation, the identification code being of a
code at a point of time when the first operating means is
operated. Distance detecting means is included to detect the
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relative moving distance between the recording head and the
recording medium in accordance with the operation of a second
operating means which functions in the recording operation, on
the basis of another identification code at a point of time when
the second operating means is operated and the identification
code memorized in the memory means. A returning movement
control means to control the relative returning movement of the
record medium to the position identified by the code at the time
when the first operating means is operated, in accordance with
the output of the distance detecting means, the returning move-
ment being controlled so as to be carried out at a predetermined
speed and then having intermittent movement when the relative
distance reaches a predetermined value. Coincidence detecting
means is also provided to detect the coincidence of a reproduced
identification code obtained from the identification recording
and reproducing means, then the identification code memorized in
the memory means during the intermittent returning movement. A
returning movement stop signal is supplied to the returning
movement control means. The device provides a tape control
system using an address signal inserted in the video signal
and control track signals so as to transport the tape faster
. . ,
and accurately to the predetermined position.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a plan view of a VTR according to one
embodiment of the present invention;
Figure 2 is a front view of a CTL head in Figure l;
Figure 3 is a block diagram of a drive control circuit
for the VTR of Figure l;
Figure 4I and Figure 4II are partial plan views of a~
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magnetic tape on which record tracks are formed;
Figure 5 is a waveform of signals at the respective
parts in Figure 3;
- Figure 6 is a view for explaining the scanning order of
the record tracks;
Figures 7-A to 7-D and A' to D' are views for explaining
the positional relationships between start tracks and stop
tracks in the recording mode; and
Figure 8 is a graph showing tape speed in the search
mode for searching the start track.
DESCRIPTIO~ OF THE PRF.FERRED E~BODI~ ITS
Figure 1 is a plan view of a VTR according to a pre-
ferred embodiment of this invention. This VTR consists of two
VTR parts I and II. The one VTR part includes a first tape
running system 1. The other VTR part includes a second tape
running system 2. The first tape running system 1 is constituted
by a supply reel (take-up reel) 3, a head drum assembly 4, a
~:,
tape drive wheel 5 and a take-up reel (supply reel) 6. Similarly,
the second tape running systen 2 is constituted by a supply reel
(take-up reel) 7, a head drum assembly 8, a tape drive wheel 9
and a take-up reel (supply reel) 10. A pair of accumulators
(vacuum columns) 13 and 14 are arranged between the first tape
running system 1 and the second tape running system 2. Portions
of magnetic tapes 11 and 12 threaded through the respective
tape running systems 1 and 2 are temporarily stored in the
accumulators 13 and 14 by vacuum action of the latter.
The four reels 3, 6, 7 and 10 are of the open-reel type.
The magnetic tapes 11 and 12 are wound on hubs of the reels 3,
6, 7 and 10, respectively. In the first tape running system 1,
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the magnetic tape 11 fed from the supply reel 3 is guided
through a predetermined tape running path by guide pins 15, 16,
17, 18, 19 and 20. Similarly, in the second tape running
system 2, the magnetic tape 12 is guided through another pre-
determined tape running path by guide pins 21, 22, 23, 24, 25 and
26. The predetermined tape running paths of the first and
second tape running systems 1 and 2 are symmetrical to each
other in the VTR according to this embodiment.
In the first tape running system 1, control track 61
(CTL head) is arranged between the guide pins lS and 19 so as
to contact with the magnetic tape 11. Similarly, in the second
tape running system 2, another CTL head 62 is arranged between
the guide pins 24 and 25 so as to contact with the magnetic
tape 12. The CTL heads 61 and 62 are the ones which can record
signals on, and reproduce signals from the magnetic tapes 11
and 12. Figure 2 is a front view of the CTL head 61 which has
the same structure as the other CTL head 62. As shown in
Figure 2, the CTL head 61 includes an upper magnetic head B
and a lower magnetic head F which are opposite to the upper and
lower marginal portions of the magnetic tape 11 shown by the
chain line in Figure 2. The magnetic heads B and F are located
substantially at the same position with respect to the longi-
tudinal direction (running direction) of the magnetic tape 11.
The rotary head drum assembly 4 includes a head drum
28 which is rotated in the clockwise direction. The other
rotary head drum assembly 8 includes a head drum 29 which is
rotated in the counter-clockwise direction. The rotational
directions of the head drums 28 and 29 are in the running
directions of the magnetic tapes 11 and 12. A magnetic head 31
is attached to a part of the peripheral portion of the head
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drum 2~. An erasing ma~netic head 32 is attached to the
peripheral portion of the head drum 28 adjacent to the magnetic
head 31. The magnetic erasing head 32 runs alon~ substantially
the same scanning path as the magnetic head 31. Similarly, a
magnetic head 33 and a magnetic erasing head 34 are attached
to a part of the peripheral portion of the head drum 29,
adjacent to each other. The magnetic heads 31 and 33 follow the
magnetic erasing heads 32 and 3~ with respect to the rotational
direction of the head drums 23 and 29, respectively. While the
previously recorded signals are erased from the magnetic tape
10 or 11 by the magnetic erasing head 32 or 34, new signals are
recorded on the magnetic tape 10 or 11 by the magnetic heads
31 and 33.
The tape drive wheel 9 for intermittently feeding the
magnetic tape 12 is arranged near the head drum assembly 8, and
it is in the form of cylindrical roller having a smaller diameter
than the rotary head drum 29. Rubber is attached to the cir-
cumferential surface of the drive wheel 9 to impart a consider-
able frictional force to the magnetic tape 12. The tape drive
wheel 9 is intermittently driven by a capstan motor 37 directly
connected to the drive wheel 9.
The tape drive wheel 5 in the first tape running system
1 has the same structure as the tape drive wheel 9 in the second
.. ..
tape running system 2. Similarly, it is intermittently driven
by a capstan motor 36 directly connected to itself. The
capstan motors 36 and 37 are, for example, DC motors. Code
generators for detecting rotational angles of the motors 36 and
. . ,~
i 37 are fixed to rotary shafts of the motors 36 and 37. The
~.
~ rotations of the motors 36 and 37 are controlled with the
- detecting outputs of the code generators.
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Next, there will be described the accumulators 13 and
14 arranged between the first tape running system 1 and the
second tape running system 2.
Through holes 38 and 39 are made in the accumulators
13 and 14 along the lengthwise directions of the accumulators
13 and 14, respectively. The through holes 3~ and 39 have
rectangular cross-section the width of which is nearly equal
to the width of the magnetic tapes 11 and 12. Air in the through
holes 38 and 39 is sucked through pipes 40 and 41 by not-shown
vacuum pumps, so that the slackened magnetic tapes 11 and 12 are
guided into the through holes 38 and 39 in the form of letter U.
A pair of sensing elements 42 and 43 for detecting the
magnetic tapes 11 and 12 are arranged at the side of the
accumulator 13. A reel motor 44 to drive the reel 3 is
rotated upon detecting output of the sensing element 42. And
a reel motor 45 to drive the reel 7 is rotated upon detecting
output of the sensing element 43. Similarly, another pair of
sensing elements 46 and 47 for detecting the magnetic tapes
11 and 12 are arranged at the side of the other accumulator 14.
A reel motor 48 to drive the reel 6 is rotated upon detecting
output of the sensing element 46. And a reel motor 49 to drive
the reel 10 is rotated upon detecting output of the sensing
element 47. Accordingly, portions of the magnetic tapes 11 and
12 of substantially predetermined length are always stored in .
the accumulators 13 and 14.
The magnetic tapes 11 and 12 are wrapped helically and
entirely around the head drums 2~ and 29 in the form of letter
a (alpha). Accordingly, record tracks are formed on the
magnetic tapes 11 and 12 at a predetermined angle to the longi-
.:.
~ tudinal direction of the magnetic tapes 11 and 12. In the
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recording operation and the reproducing operation, the magnetic
heads scan the magnetic tapes 11 and 12 while they are stopped,
respectively. Accordin~ly, the angles of the scanning paths of
the magnetic heads in the recording operation and the reproducing
operation are equal to each other regardless of tape running
speed in the reproducing operation. No noise band occurs on
the reproduced picture in any of the still re?roduction, the
slow-motion reproduction and the reverse-motion reproduction.
Next, operations of the VTR according to this embodi-
ment will be described with reference to Figure 3 to Figure 8.
.
Figure 3 is a block diagram of a drive control circuit
for the VTR part I shown in Figure 1. Another drive control
circuit for the VTR part II shown in Figure 1 is equal to that
for the VTR part I in construction. And the former operates
in a similar manner to the latter except that the former's
operation is different in timing from the latter's operation.
Figure 4-I and Figure 4-II are plan views of respective
parts of the magnetic tapes 11 and 12 on which record tracks
are formed, respectively. Figure 5 is wave forms of signals
at the respective parts of the block diagram of Figure 3.
Figure 6 is a view for explaining the scanning order o~ the
record tracks. Figures 7-A to 7-D and 7-A' to 7-D' are views
for explaining the relationships between start tracks and stop
tracks in the recording mode. And Figure 8 is a graph showing
tape speed in the search mode for searching the start track.
In the recording operation and reproducing operation of
the VTR according to this embodiment, the magnetic tapes 11
and 12 are transported forward and backward in a selected,
predetermined time interval. In the VTR part I, when the mag-
netic tape 11 is transported in the FW (forward) direction shown
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by the arrow in Figure R-I, record tracks fl~ f3 fn shown
by the solid lines are successively formed on the ma~netic tape
11. And when the magnetic tape 11 is transported in the BW
(backward) direction shown by the arrow BW in Figure 4-I,
record tracks fn+2 ---- shown by the dotted lines are
successively formed between the adjacent record-tracks shown
by the solid lines on the magnetic tape 11. Also in the VTR
part II, record tracks are formed on the magnetic tape 12 in a
similar manner. The VTR parts I and II alternately operate
every one field of video signals. Video signals of odd fields
are recorded on the magnetic tape 11 in the VTR part I, while
video signals of even fields are recorded on the magnetic tape
lZ in the VTR parts II.
In Figure 3, one of selecting buttons 51a, 51b, 51c and
51d in a time interval selection circuit 51 is selectively
pushed to set the time interval of the recording operation.
For example, time intervals of 30 seconds, 60 seconds, 2
minutes and 5 minutes can be set by the selec~ing buttons
51a, 51b, 51c and 51d, respectively. When the selecting button
51a is pushed, the magnetic tapes 11 and 12 are transported
forward and backward in the time interval of 30 seconds. In
other words, the magnetic tapes 11 and 12 are transported one
way, namely forward or backward in 15 seconds. New video signals
are successively recorded on the magnetic tapes 11 and 12 in the
time interval of 30 seconds
.
;:~ Next, operations of the VTR of this embodiment will be
~ described in relation to the code recording mode, the recording
:,
mode and the reproducing mode.
(1), Code Recording Mode
In the VTR according to this embodiment, a C~L signal,
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a VITC (Vertical Interval Time Code) signal and a color bar
video signal are recorded on the magnetic tapes 11 and 12
before video signals start to be recorded on the ma~net tapes
11 and 12. Such recording operation is hereinafter called as
"code recording mode". Other address signals which can be
inserted in the video signal can be used instead of VITC signal,
such, for example, as the address signal shown in Tachi
u.s. Patent 4,159,480, assigned to the same assignee as the
present a?plication.
l~hen a code recording mode button 66 of a recording
operation control part 64 is pushed in Figure 3, a code record-
ing mode set signal is supplied through the button 66 to a pro-
cessing circuit 53 to put the VTR into the code recording mode.
A siznal a having the vertical frequency of 60Hz is supplied
from the processing circuit 53 to a drum servo circuit 54. A
drum motor 55 is rotated at the speed of 60Hz with the output
of the drum servo circuit 54. Accordingly, the head drum ~8
for the VTR part I shown in Figure 1 is driven at the vertical
... .
frequency. The head drum ~9 for the VTR part II is rotated in
the same manner.
; A video signal Vs is supplied to a vertical synchroniz-
` ing signal separating circuit 68 through an input ter~inal 67 ofi; the drive control circuit of Figure 3. A vertical synchronizing
signal VD separated through the separating circuit 67 is supplied
to the processing circuit 53, so that the operation of the pro-
cessing circuit 53 is synchronized with the vertical synchron-
izing signal VD.
' A change-over switch 72 in Figure 3 is connected to REC
position in the code recording mode. The vertical synchronizing
signal VD is supplied to a clock input terminal CP of a flip-flop
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73, so that a change-over signal A going high at every odd field
as shown in Figure 5-A is formed at an output terminal ~ thereof.
The change-over signal A is supplied to a switching circuit 69
to switch on the latter at every odd field. Thereby, a color
bar video signal obtained from a color bar video signal
generator (not shown) is supplied to the magnetic head 31
through the input terminal 67, a mixer 70, a recording amplifier
71 and the change-over switch 72 and the switching circuit 69.
Accordingly, the color bar signal is recorded on forward- and
backward-successive tracks fl, f3 ...... on the magnetic tape 11.
On the other hand, a change-over signal B going high at every
even field as snown in Figure 5-B is formed at another output
terminal Q of the flip-flop 73. The change-over signal B is
supplied to the VT~ part II as a timing slgnal for changing over
the magnetic head 33.
A VITC signal described hereinafter is supplied to
another input of the mixer 70. The VITC signal is mixed in the
mixer 70 with the color bar video signal and is inserted into
each vertical blanking interval of the video signal. Thus,
the VITC signal is recorded on each record tracks at each
portion corresponding to the vertical blanking interval.
In the code recording mode, a capstan control signal _
is supplied from the processing circuit 53 to a capstan control
circuit 56. The cpastan motor 36 of the VTR part I is inter-
mittently driven with drive current supplied from the capstan
control circuit 56. As above described, the code generator
(not shown) is fixed on the rotary shaft of the capstan motor
36. The detecting output CG of the code generator is fed back
to the capstan control circuit 56, so that the capstan motor 36
is so controlled as to rotate by a predetermined angle in one
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of the intermittent rotations. Also, the capstan motor 37 of
the VTR part II is intermittently driven by a corresponding
capstan control circuit in the same manner as the capstan motor
36 of the VTR part I.
Figure 5C and Figure 5D show wave forms of the drive
current supplied to the capstan motors 36 and 37. The wave
forms are substantially trian~ular as shown in Figure 5C and
Figure 5D, so as to prevent steep acceleration and deceleration
of the capstan motors 36 and 37 as much as possible. One drive
,
current is supplied to the capstan motor 36 of the VT~ part I in
the even field, as shown in Figure 5C, while the other drive
current is supplied to the capstan motor 37 of the VTR part II
in the odd field, as shown in Figure 5D. Thus, in the first
- field, the magnetic tape 11 in the VTR part I stops~, while the
head drum 2~ rotates one revolution to form the track fl on
the magnetic tape 11 as shown in Figure 4-I. On the other hand,
in the first field, the tape drive wheel 9 of the VTR part II is
rotated by the predetermined angle by the capstan motor 37 to
transport the magnetic tape 12 by two pitches of record tracks
in the FW-direction.
Next, in the second field, the tape drive wheel 5 of the
VTR part I is rotated by a predetermined angle by the capstan
motor 36 to transport the magnetic tape 11 by two pitches of
record tracks in the FW-direction. On the other hand, in the
second field, the head drum 29 of the VTR part II rotates one
revolution to form a track f2 on the magnetic tape 12 as shown
in Figure 4-II. After that, in the same manner, the tracks
f3, f5, ...... of the odd fields and the tracks f4, f6' ..... of
the even fields are formed at two pïtches of record tracks
alternately on the magnetic tapes 11 and 12, respectively.
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While the magnetic tape 11 is intermittently trans-
ported in the FW direction, a switch SWl of the VTR I is closed
with the control of the processing circuit 53 in Figure 3.
Accordingly, a record CTL signal d is supplied to a CTL record-
ing circuit 57. A recording current E shown in Figure 5~ is
formed on the basis of the record CTL signal d, and it is supplied
from the CTL recording circuit 57 to the lower magnetic head F
of the CTL head 61 shown in Figure 2. In the odd field, namely,
when the magnetic tape 11 has stopped, the direction of the
recording current E is inverted from positive to negative. And
in the even field, namely, when the magnetic tape 11 is being
transported, the direction of the recording current E is in-
verted from negative to positive. As a result, a CTL track
CTL (FW) is formed on the lower marginal portion of the magnetic
tape 11. The magnetization in the CTL track CTL (FW) is inverted
. ,:
from N-polarity to S-polarity at a position corresponding to
the track fl. When the magnetic tape 11 is being transported
by the distance between the tracks fl and f3, the magnetization
in the CTL track CTL (FW) is inverted from S-polarity to
N-polarity. And the magnetization in the CTL track CTL (FW)
is again inverted from N-polarity to S-polarity at a position
corresponding to the track f3 in the condition that the magnetic
tape 11 stops.
As schematicaIly shown in Figure 4-I, signals CTLl,
CTL3, .. ....corresponding to the inversion positions from
N-polarity to S-polarity are recorded at positions corresponding
to the tracks fl, f3, ..... by the magnetic head F. While the
magnetic tape 11 stops, the signals CTLl, CTL3, ...... are
recorded on the magnetic tape 11. Accordingly, some slip between
the tape drive wheel 5 and the magnetic tape 11 which is caused
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by the intermittent drive, has no adverse influence on the
positional relationsh-ip between the tracks fl, f3, .... and
the signals CTLl, CTL3, ..... , the magnetization may be inverted
any time during the time of one field when the magnetic tape 11
stops. Accordingly, even when the inversion time of the CTL
signal d or recording current ~ varies a little, the positional
relationship between the tracks fl, f3, .. ...and the si~nals
CTLl, CTL3, .. ...is maintained constant. Further, tlle pulse
widths of the negative and positive pulses of the recording
current E do not need to be equal to each other. Slmilarly,
another recording current shown in Figure 5F is supplied to the
lower magnetic head F of the CTL head 62 in the VTR part II.
The recording current is opposite in phase to the recording
current E. The magnetization is inverted from N-polarity to
S-polarity during the time of the even field when the magnetic
tape 12 stops. Signals CTL2, CTL~, ...... are recorded on the
magnetic tape 12, corresponding to the trac~s f2, f4~ .
In the code recording mode, after the CTL signals end
to be recorded in the forward direction in half of the selected
time interval, CTL (BW) signals start to be recorded in the
backward direction with control of the processing circuit 53.
In the last forward tape transport, the magnetic tape 11 is
transported forward by one pitch of tracks, as shown in Figure
4-I, with the capstan control signal b from the processing
circuit 53. And in the next odd field, the magnetic tape 11 is
transported backward in the BW-direction by two pitches of
tracks to form a track fn+2 on the magnetic tape 11, as shown
in Figure 4-I. Thus, backward-successi~e tracks are formed
between the adjacent two of the forward successive tracks
fl, f3, ...... on the magnetic tape 11.
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The intermittent transport of the magnetic tape 11 in
the backward direction is controlled with the CTL signal
reproduced from the CTL (FW) track formed in the forward
transport. In the backward transport, the switch SW 1 is
opened, and switches SW 2 and SW 4 are closed, with the
control of the processing circuit 53. Accordingly, CTL (BW)
signals are recorded on the upper marginal portion of the
magnetic tape 11 by the magnetic head B of the CTL head 61 to
form a CTL (BW) track, while the CTL (FW) signals are repro-
,: . .
duced from the CTL(FW) track formed on the lower marginal portionby the ma~netic head F of the CTL head 61. Wlth the intermittent
baclcward transport of the magnetic tape 11, the CTL signals e
is reproduced by the magnetic head F of the CTL head 61. In
Figure 3, the reproduced CTL signal e from the magnetic head F
of the CTL head 61 is supplied to a CTL detecting circuit 53.
The positive differentiation pulses are selected at the CTL
detecting circuit 58, and is su?plied as a CTL signal f through
the switch SW 2 to the capstan control circuit 56. The drive
current c supplied from the capstan control circuit 56 is con-
trolled on the basis of the CTL signal f, the capstan control
signal _ and the output CG of the code generator respectively
supplied to the capstan control circuit 56 to control the
rotational angle of the capstan motor 36 in the reverse direction,
and hence to control the stop position of the magnetic tape 11.
Thus, the baclcward-successive tracks fn+2 ..... are rightly
formed midway between the adjacent two of the forward-successive
tracks fl, f3, ..... , respectively. In that case, since the
stop position of the magnetic tape 11 is controlled on the basis
of the CTL signal f, the positional relationship between the
record positions CTLl, CTL3, ...... in the forward CTL track and
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- the backward-successive record tracks fn~2 ~ , are very
accurate.
On the other hand, the record CTL signal d from the
processing circuit 53 is supplied throu~h the switch SW4 to
:;.
a CTL recording circuit 60 in the similar manner to the
'-~ forward CTL recording operation. A recording current E, thepolarity of which is inverted at the period of one field as
j shown in Figure 5E, is supplied from the CTL recording circuit
,; 60 to the magnetic head B of the CTL head 61. As a result,
the backward CTL (BW) track is formed on the upper marginal
, portion of the magnetic tape 11. Accordingly, CTL record spots
CTLn~2 .. ., as shown by the dotted lines in Figure 4-I, are
formed in correspondence with the backward-successive tracks
. ~ .
fn+2~ ... The CTL record spots CTLl, CTL3, ...... on the
forward CTL track positionally correspond to the tracks fl,
f3, ..... . Further, the positional relationship between the
CTL record spots CTLl, CTL3, ..... , the backward-successive
tracks fn+2 ~ and the CTL record spots CTLn+2 ........... on
the backward CTL track, are accurately regulated. Accordin~ly,
also the positional relationship between the CTL record spots
CTLn+2 ...... on the backward CTL track and the forward-successive
tracks fl, f3, ...... is accurate.
Thus, as shown in Figure 6, first in the forward record-
ing operation in the ~TR part I, a color bar video signal of an
odd field in a frame numbered as 00 sec 00 F (Frame) is recorded
on the first track fl of the magnetic tape 11, and then a video
signal of a frame number 00 sec 01 F is recorded on the second
track f3 of the magnetic tape 11 which is distant by two
pitches of tracks from the first track. Hereafter, video signals
of 00 sec 02 F, ..... .are recorded on the successive tracks of
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the maOnetic tape ll which are distant by two pitches from
each other. A video signal of 14 sec 29 F is recorded on the
last track of the magnetic tape 11. The last track is distant
by one pitch of tracks from the previous track on which a
video signal of a frame number l~ sec 28 F is recorded. ~ext,
the magnetic tape ll is intermittently transported by two
pitches of tracks in the backward direction to record video
signals of frame numbers 15 sec 00 F, 15 sec 01 F, ..... ln
order. And a video signal of a frame number 29 sec 29 F is
recorded on the last of the backward-successive tracks distant
by one pitch o:E tracks from the previous track on which a
video signal of a frame number 29 sec 28 F is recorded.
Then, the ma~netic tape ll is transported by two pitches
of tracks in the forward direction to the position where the
magnetic head 31 traces the first track fl. In the VTR part II,
in parallel with the VT~ part I, the video signal of each even
field in the frames from 00 sec 00 F to 29 sec 29 F is recorded
on each track of the tape 12. After that, the tape 12 is
returned to the position where the magnetic head 32 traces the
first track f2. Thus, one cycle of the code recording mode is
accomplished. At that time, the ~rP~ is changed to the repro-
ducing mode. The color bar signal of 00 sec 00 F recorded on
the fi~st tracks fl and f2 is displayed as still picture.
In the code recording mode, the VITC signal corresnond-
ing to the frame number (00 sec 00 F .... ) of each track is
formed in the VITC signal generating circuit 7~ in digital code
form. The VITC signal is recorded in the vertical blanking
period of each track, as shown in Figure 7.
~ hen the code recording mode is finished, the recordedcolor bar video signal may be reproduced to moni-tor the repro-
duced picture for checking up the presence of signal dropouts
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due to any damage of the coated surface of the tapes. The
reproduction of the color bar is performed ~7ith the reproducing
mode described hereinafter. T~len the signal dropouts occur, an
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auto-feed button 76 of an auto-feed operation control part 75
is operated. A control signal is supplied to the processing
circuit 53 through an auto-feed control circuit 77. On the
basis of the above control signal, a capstan control signal b
is formed, and it is supplied to the capstan control circuit 56,
which controls the capstan motor 36 to feed the tape fast in
the forward direction. When an output of a CTL detecting
circuit 7$ for detecting the presence of the reproduced CTL
signal f goes low, the Lape feed stops. Then, the code record-
ing button 66 of the recording operation control part 64 is
again operated to record the CTL signal, VITC signal and color
bar video signal on a new portion of the magnetic tape.
Recording Mode
After the code recording mode is finished, the VTR is
put into a recording mode with operation of a recording button
65 of the recording operation control part 6~. In the record-
ing mode, the signal on the track fl which is traced with the
magnetic head 31 of the head drum 28 is reproduced. A repro-
duced video signal ~ is supplied to a VITC signal detecting
circuit ~0 through a reproducing amplifier 79. The VITC
signal corresponding to 00 sec 00 F is read by the VITC signal
detecting circuit 80. The VITC signal is supplied to the
VITC signal generating circuit 74 to set the circuit 74 in the
condition of the time code 00 sec 00 F of the signal _.
Then, the change-over switch 72 of Figure 3 is changed
over to REC position and the VTR starts recording operation.
The video signal Vs is alternately recorded on the tracks
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fl, f3, ...... and f2, f~, ...... on the magnetic tapes 11 and 12
which are intermittently transported alternately in the VT2 I
and VTR II. New video signal Vs is recorded on the magnetic
tapes 11 and 12 at the set repeat period of 30 seconds. In
the recording mode, the VITC signal is recorded on each track
in the same manner as the code recording mode. In Figure 3,
the switches SW 1 and SW 4 are opened with control of the
processing circuit 53. Further, in the forward transport of
the magnetic tape 11, the switch SW 3 is closed, and in the
backward transport of the magnetic tape 11, the switch Sl~ 2 is
c~osed, with the control of the processing circuit 53.
Accordingly, in the forward recording mode, the stop
position of the magnetic tape 11 is controlled with the CTL
signal obtained from the bac~ward CTL (~W) track, and the video
si~nal is recorded on the trac~s fl, f3, ..... , while the
magnetic head 31 scans the tracks fl, f3, ....... . In the
backward recording mode, the stop position of the magnetic tape
11 is controlled with CTL signal obtained from the forward
CTL (FW) track, and the video signal is recorded on the tracls
fn+2 ~ while the magnetic head 31 scans the trac~s fn+2
(2)-A Start ~Iode
In the recording mode, when a start switch 81 in Figure
3 is pushed, the VT~ is put into a start mode. The start switch
81 may be operated in the case when searching of the top or
initiation of a desired scene to be recorded is required. At
the point of the time when the start switch 81 is pushed, the
time code, that is, an outpu~ of the VITC signal generating
circuit 74 is memorized in a memory S2. The content of the
memory 82 is supplied to a comparator 83. On the other hand, the
output of the VITC signal generating circuit 74 is supplied to
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- ~139~3~
an input terminal A of a selector 84. A control signal is
:~ supplied to a control terminal K of the selector 84 from the
processing circuit 53 after the start switch 81 is operated.
With the control signal, the input terminal A is selected in
.
the selector 84. Accordingly, in the start mode, the output
of the VITC signal generating circuit 74 is supplied to another
input of the comparator 8~ through the selector 84. Thus, after
the selected period of 30 seconds has passed since the point
of time when the start switch 81 is pushed, the time code of
the output of the VITC signal generating circuit 74 coincides
with the time code of the content in the memory 32. As a
result, a coincidence signal is supplied from the comparator
83 to the processing circuit 53, which produces a capstan control
signal b to stop the capstan motor 36. Thus, the transport of
the tape 11 stops and the recording operation is finished.
Thus, only one cycle of recording operation for the
time period designated by the interval selection circuit 51 is
performed after the start switch 81 is operatcd. Accordingly,
there is no trouble of missing the desired recording scene
through careLessness. Further, since the top of the recorded
scene is found out at the time when the recording operation is
finished, the VTR may immediately start the reproducing operation
from the top of the recorded scene.
The output of the VITC signal generating circuit 74
is supplied to a display unit 85. The display unit 85 consists
of, for example, plural display elements, for example, light
emitting diodes, arranged in a line. These elements light in
order to form a bar-graph-like display in accordance with
change of the VITC signal. The whole lighting (full scale)
of the display unit 85 corresponds to the period designated
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: ~13~32
` :-
through the interval selection circuit 51. Therefore, by
monitoring the display unit 85 for the scene to be recorded,
- the start switch 81 may be operated again to secure another one
cycle of the recording period when the desired scene to be
recorded seems to become longer.
:
Search Mode
When a stop switch 89 is pushed within the selected
recording period (30 seconds, for example) in the start mode,
` the VTR is put into a search mode for finding out the record
track identified by the time code corresponding to the time
when the start switch 81 is operated. When the stop switch
89 is pushed, the time code at the point of time, that is,
the output of the VITC signal generating circuit 74, is
supplied to the processing circuit 53 through the stop switch
89, and is memorized in a memory in the processing circuit 53.
The recording operation of the VTR is stopped with the control
of the processin~ circuit 53 at the time when the stop switch
;~ 89 is operated. In the processin~ circuit 53, there is per-
formed a calculation of the distance between the start track
and the stop track on the magnetic tape on the basis of the
content of the memory memorizinv the time code corresponding
` to the time when the stop switch 89 is operated and the con-tent of the memory 82 memorizing the time code corresponding
to the time when the start switch 81 is operated.
Figures 7-A to 7-D and Figures 7-A' to 7-D' show the
positional relationships between the start tracks fs and the
stop tracks fe. Figures 7-A to 7-D show the cases where the
start track is is situated at one of the forward successive
- tracks fl, f3, ..... , and Figures 7-A' to 7-D' show the cases
when the start track fs is situated at one of the backward
;~ ~13~432
.
successive tracks fn+2 ...... . In the calculation of the
distance between the start track fs and the stop track feJ
difference (T) between respective corresponding time codes
ts and te~ namely, T = te ~ ts. is calculated.
As a positive result, T is obtained by the calcula-
tion in the cases A and A', the magnetic tape is moved for
searching in the direction opposite to the direction of the
tape transportation to form the successive-tracks containing
the start track fs. Namely, in Figure 7-A, the magnetic tape
is moved in the backward direction, fs~ fe~ to search the top
of the reproducing scene, and in Figure 7-A', the magnetic
ta~e is moved in the forward direction, fe~ fs- to search the
top of the reproducing scene.
Since the distance T can not be directly calculated
in the cases shown in Figures 7-B and 7-B'; the time code te
of the stop track fe is exchanged to a time code te' of the
track being adjacent to the stop track fe. Namely, in
Figure 7-B, the time code te is exchanged to the corresponding
time code of the adjacent forward successive track fe' and
in Figure 7-B', the time code te is exchanged to the correspond-
ing time code of the adjacent backward successive-track fel,
and then, distance T between fs and fe' is calculated. The
exchange of the time code may be performed through an encoder
which exchange the code between the forward successive tracks
and the backward successive tracks. The code exchange may be
carried out in response to the detection of turning of the
tape transportation. As a positive result, T is obtained by
the calculation : T = te' - ts, the tape ls moved for
searching in the backward direction fs~ fe as in Figure 7-B,
or in the forward direction fe~ fs as in Figure 7-B', in the
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~39!43~
same manner as Figures 7-A or 7_~1.
Si~ilarly, in the cases of Figures 7-C and 7-C', the
time code of the stop track fe is exchanged to that of the
adjacent successive track on the start side, and then, the
; distance T is calculated. Since the difference T shows a
negative value, the tape is moved in the forward direction
fe~ fs in the case C and in the bac~ward direction fs~ fe in
the case c", that is, in opposite direction to the cases A, A'
and B, B'.
In the cases of Figures 7-D and 7-D', since the
direction of direction of tape transportation is turned twice,
the exchange of the time code o~ the stop track fe is not
required. The exchange of time code may be carried out only
when the turning of the direction of tape transportation is
once effected. The distance T = te ~ ts is directly calculated
in the cases D and D'. The distance T shows a negative value
in each case, and so the tape is moved for searching in the
direction fe~ fs in the case D, and in the direction fs~ fe
in the case D', in the opposite manner to the cases A and A'.
Thus, the tape feed direction for the searchin~ is
determined in accordance with negative or positive sign of the
distance T and the number of turnings of the tape transporta-
tion. Further, the tape feed speed is determined in accordance
with the value of calculated distance T in the processing
circuit 53. For example, as shown in Figure 8, when the
distance T shows more than 100 frames, the tape is continuously
fed at a first feed speed Vs until the distance becomes less
than 100 frames. Then, the tape is continuously fed at a second
feed speed Vf until the difference becomes less than lq frames.
After that, the tape is intermittently transported for searching
:'' .
-24-
~ ~ 3~3~
the top of the reproducing scene during the 10 frames.
- In that search mode, the reproduced CTL signals are
subtracted one by one from the calculated distance T to detect
the positions being of 100 frames and 10 frames far from the
start track fs~ when the tape is fed at the first feed speed
Vs and the second feed speed Vf. After the result of sub-
traction becomes less than 10 frames, the tape is intermittently
transported and each stop position of the tape is controlled
with servo control to the capstan motor 36 on the basis of the
reproduced CTL signal f. In this case, the CTL signal on the
CTL track for the successive-tracks opposite to the start
track fs is used. Therefore, for example, when the start
track fs is included in the forward successive tracks, a
reproducing signal obtained from the backward CTL track CTL (B~J)
i is used for the servo control. Though there is some mis-tracking at the time when the tape feeding condition is changed
to the intermittent transportation from the continuous feeding,
an accurate tracking is achieved through the capstan servo
control, so that the VITC signal can be detected by the
tracking.
In Figure 3, when the VTR is put into the search mode
by operating the stop switch 89, a B input is selected in the
selector 84 by a control signal from the processing circuit
53. Therefore, the VITC signal detected through the VITC
signal detecting circuit 80 is supplied to the comparator 83
through the selector 84. To another input of the comparator
83, the VITC signal of the start track memorized in the memory
82 is supplied. The top of the recorded scene can be found
out by detecting the coincidence of the VITC signal and the
content of the memory 82 with each other. The output of the
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113~43Z
comparator 83 is supplied to the processing circuit 53, which
generates a capstan control signal b to stop the intermittent
transportation of the capstan motor 36.
(3), Reproducing Mode
The VT~ may be put into a reproducing mode after the
search mode is finished. The reproducing mode is automatically
obtained after the top of the recorded scene has been found
out through the search mode. Alternatively, the VTR may be
put into a stop mode after the finish of the search mode, and
the VTR may be put into the reproducing mode with operation of
a reproducing button (not shown). In the reproducing mode,
the change over switch 72 is switched to PB position. Accord-
ingly, a reproduced signal obtained from the magnetic head 31
is led out from an output terminal 91 through the switching
circuit 69, the change-over switch 72, the reproducing ampli-
fier 79 and a selector 90. The selector 90 is provided to
change over alternately the reproduced signals from the VTR
part I and VTR part II at every field. The selector 90 is
controlled by a change-over signal formed on the basis of the
output PG of the pulse generator for detecting the rotational
position of the drum motor 55.
Tape runnin~ speed in the reproduction is selected
through a tape speed selection control part 92. The output
of the control part 92 is supplied to the processing circuit
53, which generates a capstan control signal b to determine
. the period of the intermittent drive of the capstan motor 36.
- The slow reproduction mode, the still reproduction mode and the
i normal reproduction mode are selected by operating the tape
speed selection control part 92. In these reproduction modes,
the reproduced VITC signal is supplied from the VITC signal
-26-
~ '
~3~3;Z
detecting circuit 80 to the display unit 85 which has plural
display elements arranged in a line to form a bar-graph-like
display such as used in the recording operation. The scanning
position of the record tracks can be recognized by light-out
of the display elements in order in accordance with change
of the VITC signal. Further, the VITC signal is supplied to
a time display part 93 through the processing circuit 53 to
display the frame number of the reproducing track.
In the reproducing mode, each stopping position of
the intermittent transportation of the tape is controlled on
~;,
the basis of CTL signal recorded in the code recording mode
to trace the record track for reproduction of the recorded
signal. The reproduced VITC signal from the VITC signal
detecting circuit ~0 is supplied to the processing circuit 53
to be compared with the VITC signal memorized in the pro-
cessing circuit 53, that is, the time code of the stop track
fe at the point of time when the stop switch 89 is pushed.
When the reproduced VITC signal coincides with the memorized
VITC signal, the reproduction for the desired scene is over,
and next operation is performed in accordance with operation
of a reproducing operation control part 94.
When a stop button 95 of the reproducing operation
control part 94 has been pushed, the tape transportation is
stopped at the time when the reproducing operation is finished.
Then, the VTR remains in the still reproducing mode. The
VTR may again be put into the recording mode with operation
of the recording button 65 of the recording operation control
part 64. Alternatively, when a STOP REC button 96 of the
reproducing operation control part 94 has been pushed, the VTR
is automatically put into the xecording mode. In that case,
-~7-
~.~.3~
next desired scene to be recorded is never passed over.
Accordin~ to this invention, relative returning move-
ment of a recording head and a recording medium to the top of
the recorded scene can be certainly and rapidly performed.
Though, in the above embodiment, each of the tapes in
both VTRs is driven every other field, this invention may be
applied to a device in which each of the tapes is driven every
- other frame. In that case, one frame signal should be recorded
either as one track on the tape by one recording head, or as a
pair of adjacent tracks by two recording heads which ~scan the
tape simultaneously but record each track alternatively.
It will be apparent to those skilled in the art that
many modifications and variations may be effected without
departing from the spirit and scope of the novel concepts of
the present invention.
.,.
.,
:
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