U.S. patent application number 09/186816 was filed with the patent office on 2001-08-16 for system for recording and reproducing data having scheme for minimizing variation in record track width when recording at different data rates.
Invention is credited to KOBAYASHI, MASAAKI, KUNIHIRA, TADASHI, MOTOSUGI, MASAHIRO, TAKEUCHI, AKIHIRO, YANAGAWA, YOSHIFUMI.
Application Number | 20010013987 09/186816 |
Document ID | / |
Family ID | 27292831 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010013987 |
Kind Code |
A1 |
YANAGAWA, YOSHIFUMI ; et
al. |
August 16, 2001 |
SYSTEM FOR RECORDING AND REPRODUCING DATA HAVING SCHEME FOR
MINIMIZING VARIATION IN RECORD TRACK WIDTH WHEN RECORDING AT
DIFFERENT DATA RATES
Abstract
At least three heads are mounted on a rotary drum. Between the
first and third heads which are located in close proximity to each
other and have different azimuth angles, a minute height difference
is formed in the rotation shaft direction of the rotary drum.
Signals of a plurality of data rates are recorded and reproduced by
using the first and second heads or the first and third heads. Two
heads having the same azimuth angle are disposed on the rotary drum
so as to be opposed each other at a central angle of 180.degree..
In search speed reproduction, search data are reproduced by the two
heads. Tracks are divided in the unit of plural tracks so as to
form track sets. Search data areas of each track set are disposed
at a position of each track which is separated from the edge of a
tape by a predetermined distance. In search speed reproduction, the
phases of the tracks and the heads are controlled, and all
effective data of the search data areas are reproduced by plural
scans of the heads.
Inventors: |
YANAGAWA, YOSHIFUMI; (KYOTO
CITY, JP) ; KUNIHIRA, TADASHI; (OSAKA CITY, JP)
; MOTOSUGI, MASAHIRO; (KATANO CITY, JP) ;
TAKEUCHI, AKIHIRO; (IKOMA CITY, JP) ; KOBAYASHI,
MASAAKI; (KAWANISHI CITY, JP) |
Correspondence
Address: |
AKIN, GUMP, STRAUSS, HAUER & FELD, L.L.P.
ONE COMMERCE SQUARE
2005 MARKET STREET, SUITE 2200
PHILADELPHIA
PA
19103
US
|
Family ID: |
27292831 |
Appl. No.: |
09/186816 |
Filed: |
November 5, 1998 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09186816 |
Nov 5, 1998 |
|
|
|
08612353 |
Mar 7, 1996 |
|
|
|
6014278 |
|
|
|
|
Current U.S.
Class: |
360/72.2 ;
360/64; 386/317; G9B/15.016; G9B/15.017; G9B/15.03; G9B/15.055;
G9B/15.088; G9B/5.015; G9B/5.177 |
Current CPC
Class: |
G11B 15/1875 20130101;
G11B 5/531 20130101; G11B 15/4673 20130101; G11B 15/467 20130101;
G11B 5/534 20130101; G11B 15/12 20130101; G11B 5/0086 20130101;
G11B 15/125 20130101; G11B 15/6655 20130101 |
Class at
Publication: |
360/72.2 ;
360/64; 386/68; 386/69 |
International
Class: |
G11B 015/18 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 7, 1995 |
JP |
7-046972 |
Mar 13, 1995 |
JP |
7-052559 |
Apr 21, 1995 |
JP |
7-096400 |
Claims
What is claimed is
1. A recording end reproducing apparatus comprising: tape driving
means for driving a tape; a rotary drum around which the tape is to
be slantly wound; at least three heads including a first head, a
second head, and a third head which are mounted on said rotary drum
and which scan the tape to conduct a recording or reproducing
operation; and a head control unit which selects said three heads,
said first head having a first azimuth angle, said second and third
heads having a second azimuth angle, said first head and said
second head being mounted on said rotary drum to be opposed each
other at a central angle of 180 degrees and at the same height in a
rotation shaft direction of said rotary drum, said third head being
located in close proximity to said first head in a direction along
the circumference of said rotary drum with a minute difference in
central angle and a minute height difference in the rotation shaft
direction of said rotary drum, and said apparatus recording and
reproducing a plurality of signals of different data rates.
2. A recording and reproducing apparatus according to claim 1,
wherein, when a track pitch is Tp, the difference in central angle
between positions of mounting said first and third heads is .theta.
degrees, and M.sub.2 is a positive even number, the minute height
difference is Tp.times..theta./(180.times.M.sub.2).
3. A recording and reproducing apparatus according to claim 1,
wherein, when a track pitch is Tp and the difference in central
angle between positions of mounting said first and third heads is
.theta. degrees, the minute height difference is not smaller than
Tp.times..theta./720 degrees and not larger than
Tp.times..theta./360.
4. A recording and reproducing apparatus comprising: tape driving
means for driving a tape; a rotary drum around which the tape is to
be slantly wound; at least three heads including a first head, a
second head, and a third head which are mounted on said rotary drum
and which scan the tape to conduct a recording or reproducing
operation; and a head control unit which selects said three heads,
said first head having a first azimuth angle, said second and third
heads having a second azimuth angle, said first head and said
second head being mounted on said rotary drum to be opposed each
other at a central angle of 180 degrees and at the same height in a
rotation shaft direction of said rotary drum, said third head being
located in close proximity to said first head in a direction along
the circumference of said rotary drum with a minute difference in
central angle and a minute height difference in the rotation shaft
direction of said rotary drum, in record or reproduction at a data
rate which is approximately one M.sub.1-th a data rate which is a
standard (where M.sub.1 is a positive odd number), a recording or
reproducing operation being conducted while said tape driving means
drives the tape to run at a speed which is one M.sub.1-th a
reference tape speed, and said head control unit controls said
first and second heads to alternately enter an operation state
during one scan period for every M.sub.1/2 revolutions of said
rotary drum, and in record or reproduction at a data rate which is
approximately one M.sub.2-th a data rate which is a standard (where
M.sub.2 is a positive even number), a recording or reproducing
operation being conducted while said tape driving means drives the
tape to run at a speed which is one M.sub.2-th a reference tape
speed, and said head control unit controls said first and third
heads to alternately enter an operation state during one scan
period for every M.sub.2/2 revolutions of said rotary drum.
5. A recording and reproducing apparatus comprising: tape driving
means for driving a tape; a rotary drum around which the tape is to
be slantly wound; and at least three heads including a first head,
a second head, and a third head which are mounted on said rotary
drum and which scan the tape to conduct a recording or reproducing
operation, said first head having a first azimuth angle, said
second and third heads having a second azimuth angle which is
different from the first azimuth angle, said first and second heads
being mounted on said rotary drum to be opposed each other at a
central angle of 180 degrees, said first head being located in
close proximity to said third head in a direction along the
circumference of said rotary drum, and said apparatus recording and
reproducing a plurality of signals of different data rates.
6. A recording and reproducing apparatus according to claim 5,
wherein said first and second heads have a mutual positional
relationship in which there is a first minute height difference in
the rotation shaft direction of said rotary drum, and said first
and third heads have a mutual positional relationship in which
there is a second minute height difference in the rotation shaft
direction of said rotary drum.
7. A recording and reproducing apparatus according to claim 6,
wherein, when a track pitch is Tp, the minute difference in central
angle between said first head and said third head in the direction
along the circumference of said rotary drum is .theta. degrees, and
M.sub.2 is a positive even number, said first and third heads have
a mutual positional relationship in which the second minute height
difference in the rotation shaft direction of said rotary drum is
Tp.times..theta./(180.times.M.sub.- 2), and said first and second
heads have a mutual positional relationship in which the first
minute height difference in the rotation shaft direction of said
rotary drum is Tp.times..theta./180.
8. A recording and reproducing apparatus according to claim 6,
wherein, when a track pitch is Tp, and the minute difference in
central angle between said first head and said third head in the
circumferential direction of said rotary drum is .theta. degrees,
said first and third heads have a mutual positional relationship in
which the second minute height difference in the rotation shaft
direction of said rotary drum is Tp.times..theta./360, and said
first and second heads have a mutual positional relationship in
which the first minute height difference in the rotation shaft
direction of said rotary drum is Tp.times..theta./180.
9. A recording and reproducing apparatus according to claim 5,
wherein said first and third heads have a mutual positional
relationship in which said heads are at the same height in the
rotation shaft direction of said rotary drum, and said first and
second heads have a mutual positional relationship in which there
is a minute height difference in the rotation shaft direction of
said rotary drum.
10. A recording and reproducing apparatus according to claim 9,
wherein, when a track pitch is Tp, the minute difference in central
angle between said first head and said third head in the direction
along the circumference of said rotary drum is .theta. degrees, and
M.sub.1 is a positive odd number, and said first and second heads
have a mutual positional relationship in which the minute height
difference in the rotation shaft direction of said rotary drum is
Tp.times..theta./(180.tim- es.M.sub.1).
11. A recording and reproducing apparatus according to claim 9,
wherein, when a track pitch is Tp, and the minute difference in
central angle between said first head and said second head in the
circumferential direction of said rotary drum is .theta. degrees,
and said first and second heads have a mutual positional
relationship in which the minute height difference in the rotation
shaft direction of said rotary drum is Tp.times..theta./180.
12. A recording and reproducing apparatus comprising: tape driving
means for driving a tape; a rotary drum around which the tape is to
be slantly wound; and at least three heads including a first head,
a second head, and a third head which are mounted on said rotary
drum and which scan the tape to conduct a recording or reproducing
operation, said first head having a first azimuth angle, said
second and third heads having a second azimuth angle, said second
head and said third head being mounted on said rotary drum to be
opposed each other at a central angle of 180 degrees, said first
head being located in close proximity to said third head in a
direction along the circumference of said rotary drum with a minute
difference in central angle, in record or reproduction at a data
rate which is approximately one M.sub.1-th a data rate which is a
standard (where M.sub.1 is a positive odd number), a recording or
reproducing operation being conducted while said tape driving means
drives the tape to run at a speed which is one M.sub.1-th a
reference tape speed, and said head control unit controls said
first and second heads to alternately enter an operation state
during one scan period for every M.sub.1/2 revolutions of said
rotary drum, and in record or reproduction at a data rate which is
approximately one M.sub.2-th a data rate which is a standard (where
M.sub.2 is a positive even number), a recording or reproducing
operation being conducted while said tape drives means driving the
tape to run at a speed which is one M.sub.2-th a reference tape
speed, and said head control unit controls said first and third
heads to alternately enter an operation state during one scan
period for every M.sub.2/2 revolutions of said rotary drum.
13. A recording and reproducing apparatus in which data are
sequentially recorded in and reproduced from adjacent tracks by a
plurality of heads which are mounted on a rotary drum and have
different azimuth angles, wherein said apparatus comprises a
plurality of heads having at least one of the azimuth angles, a
normal data area which is used in normal speed reproduction, and
one or more search data areas which are used in search speed
reproduction are disposed in one track, said search data areas of a
track set consisting of a plurality of tracks are disposed at a
position of each track which is separated from the edge of a tape
by a predetermined distance, said search data areas of the track
set have the same data, and, in search speed reproduction, the same
data are complementarily reproduced by using said plurality of
heads.
14. A recording and reproducing apparatus in which data are
sequentially recorded in and reproduced from adjacent tracks by a
plurality of heads which are mounted on a rotary drum and have
different azimuth angles, wherein said apparatus comprises two or
more heads having at least one of the azimuth angles, a normal data
area which is used in normal speed reproduction, and one or more
search data areas which are used in search speed reproduction are
disposed in one track, a reference speed for search speed
reproduction is N.sub.1-fold speed (where N.sub.1 is a positive odd
number), said search data areas of a track set consisting of
N.sub.1 or more tracks which are alternately selected are disposed
at a position of each track which is separated from the edge of a
tape by a predetermined distance, and said search data areas of the
track set have the same data.
15. A recording and reproducing apparatus in which data are
sequentially recorded in and reproduced from adjacent tracks by a
plurality of heads which are mounted on a rotary drum and have
different azimuth angles, wherein said apparatus comprises two or
more heads having the azimuth angles, a normal data area which is
used in normal speed reproduction, and one or more search data
areas which are used in search speed reproduction are disposed in
each track, a reference speed for search speed reproduction is
N.sub.2-fold speed (where N.sub.2 is a positive integer), said
search data areas of a track set consisting of N.sub.2 or more
continuous tracks are disposed at a position of each track which is
separated from the edge of a tape by a predetermined distance, and
said search data areas of the track set have the same data.
16. A recording and reproducing apparatus according to claim 14,
wherein said apparatus has a plurality of reference speeds for
search speed reproduction, and a plurality of search data areas are
disposed for each of the reference speeds for search speed
reproduction.
17. A recording and reproducing apparatus in which data are
sequentially recorded in and reproduced from adjacent tracks by a
plurality of heads which are mounted on a rotary drum and have
different azimuth angles, wherein a normal data area which is used
in normal speed reproduction, and one or more search data areas
which are used in search speed reproduction are disposed in each
track, said search data areas of each track set consisting of a
plurality of tracks are disposed at a position of each track which
is separated from the edge of a tape by a predetermined distance,
said search data areas of the track set have the same data,
positional relationships between the track and said heads are
controlled in search speed reproduction, and the data of said
search data areas of the track set are reproduced by a plurality of
scans of said heads.
18. A recording and reproducing apparatus in which data are
sequentially recorded in and reproduced from adjacent tracks by a
plurality of heads which are mounted on a rotary drum and have
different azimuth angles, wherein a normal data area which is used
in normal speed reproduction, and one or more search data areas
which are used in search speed reproduction are disposed in each
track, a reference speed for search speed reproduction is
(N.sub.3+0.5)-fold speed (where N.sub.3 is a positive integer),
said search data areas of each track set consisting of
(2.times.N.sub.3+1) or more tracks which are alternately selected
are disposed at a position of each track which is separated from
the edge of a tape by a predetermined distance, positional
relationships between the track and said heads are controlled in
(N.sub.3+0.5)-fold speed reproduction, and the data of said search
data areas of the track set are reproduced by a plurality of scans
of said heads.
19. A recording and reproducing apparatus according to claim 18,
wherein said search data areas are disposed on a track along which
said heads scan in (2.times.N.sub.3)-fold speed reproduction.
20. A recording and reproducing apparatus in which data are
sequentially recorded in and reproduced from adjacent tracks by a
plurality of heads which are mounted on a rotary drum and have
different azimuth angles, wherein said apparatus comprises two or
more heads having at least one of the azimuth angles, a normal data
area which is used in normal speed reproduction, and one or more
search data areas which are used in search speed reproduction are
disposed in each track, a reference speed for search speed
reproduction is N.sub.1-fold speed (where N.sub.1 is a positive odd
number), said search data areas of a track set consisting of
N.sub.1 or more tracks which are alternately selected are disposed
at a position of each track which is separated from the edge of a
tape by a predetermined distance, said search data areas of the
track set have the same data, positional relationships between the
track and said heads are controlled in N.sub.1-fold speed
reproduction, and the data of said search data areas of the track
set are reproduced by a plurality of scans of said heads.
21. A recording and reproducing apparatus according to claim 20,
wherein said search data areas are disposed on a track along which
said heads scan in (2.times.N.sub.1)-fold speed reproduction.
22. A recording and reproducing apparatus in which data are
sequentially recorded in and reproduced from tracks by a plurality
of heads which are mounted on a rotary drum and have different
azimuth angles, wherein a normal data area which is used in normal
speed reproduction, and one or more search data areas which are
used in search speed reproduction are disposed in each track, a
reference speed for search speed reproduction is N.sub.4-fold speed
(where N.sub.4 is a positive even number), said search data areas
of a track set consisting of (2.times.N.sub.4) or more continuous
tracks are disposed at a position of each track which is separated
from the edge of a tape by a predetermined distance, said search
data areas of the track set have the same data, positional
relationships between the track and said heads are controlled in
N.sub.4-fold speed reproduction, and the data of said search data
areas of the track set are reproduced by a plurality of scans of
said heads.
23. A recording and reproducing apparatus according to claim 22,
wherein said search data areas are disposed on a track along which
said head scans in (2.times.N.sub.4-1)-fold speed reproduction.
24. A recording and reproducing apparatus in which data are
sequentially recorded in and reproduced from adjacent tracks by a
plurality of heads which are mounted on a rotary drum and have
different azimuth angles, wherein a normal data area which is used
in normal speed reproduction, and one or more search data areas
which are used in search speed reproduction are disposed in each
track, said search data areas of a track set consisting of a
plurality of tracks are disposed at a position of each track which
is separated from the edge of a tape by a predetermined distance,
said search data areas of the track set have the same data, and a
part or the whole of data are recorded in said search data areas in
a repeated manner in a longitudinal direction of the track.
25. A recording and reproducing apparatus in which data are
sequentially recorded in and reproduced from adjacent tracks by a
plurality of heads which are mounted on a rotary drum and have
different azimuth angles, wherein a normal data area which is used
in normal speed reproduction, and one or more search data areas
which are used in search speed reproduction are disposed in each
track, said search data areas of a track set consisting of a
plurality of tracks are disposed at a position of each track which
is separated from the edge of a tape by a predetermined distance,
said search data areas of the track set have the same data, and all
effective data of said search data areas are reproduced by W or
more scans (where W is an integer which is not less than 3) of said
search data areas.
26. A recording and reproducing apparatus in which data are
sequentially recorded in and reproduced from adjacent tracks by a
plurality of heads which are mounted on a rotary drum and have
different azimuth angles, wherein a normal data area which is used
in normal speed reproduction, and one or more search data areas
which are used in search speed reproduction are disposed in each
track, said search data areas of a track set consisting of K or
more (where K is an integer which is not less than 4) tracks which
are alternately selected are disposed at a position of each track
which is separated from the edge of a tape by a predetermined
distance, said search data areas of the track set have the same
data, and, in K/W-fold speed reproduction (where W is an integer
which is not less than 3 and K/W is not an integer), all effective
data of said search data areas are reproduced by W or more scans of
said search data areas.
27. A recording and reproducing apparatus in which data are
sequentially recorded in and reproduced from adjacent tracks by a
plurality of heads which are mounted on a rotary drum and have
different azimuth angles, and a control signal is recorded and
reproduced in a longitudinal direction of a tape, wherein a normal
data area which is used in normal speed reproduction, and one or
more search data areas which are used in search speed reproduction
are disposed in each track, said search data areas of a track set
consisting of a plurality of tracks which are alternately selected
are disposed at a position of each track which is separated from
the edge of the tape by a predetermined distance, said search data
areas of the track set have the same data, and delimitation of the
track set is indicated by the control signal.
28. A recording and reproducing apparatus in which data are
sequentially recorded in and reproduced from adjacent tracks by a
plurality of heads which are mounted on a rotary drum and have
different azimuth angles, wherein a normal data area which is used
in normal speed reproduction, and one or more search data areas
which are used in search speed reproduction are disposed in each
track, and an AUX area is disposed in a part of said search data
areas.
29. A recording and reproducing method in which data are
sequentially recorded in adjacent tracks by a plurality of heads
which are mounted on a rotary drum and have different azimuth
angles, and data are reproduced from the tracks by a plurality of
heads which have at least one of the azimuth angles, wherein said
method comprises format steps in which a normal data area which is
used in normal speed reproduction, and one or more search data
areas which are used in search speed reproduction are disposed in
each track, said tracks are divided into track sets having a
plurality of tracks, said search data areas of the track set are
disposed at a position of each track which is separated from the
edge of a tape by a predetermined distance, and the same data are
disposed in said search data areas of the track set.
30. A recording and reproducing method according to claim 29,
wherein a reference speed for search speed reproduction is
N.sub.1-fold speed (where N.sub.1 is a positive odd number), and
said method further comprises a format step in which tracks are
divided into track sets having N.sub.1 or more tracks which are
alternately selected.
31. A recording and reproducing method according to claim 29,
wherein two or more heads have different azimuth angles, a
reference speed for search speed reproduction is N.sub.2-fold speed
(where N.sub.2 is a positive integer), and said method further
comprises a format step in which tracks are divided into track sets
having N.sub.2 or more continuous tracks.
32. A recording and reproducing method in which data are
sequentially recorded in adjacent tracks by a plurality of heads
which are mounted on a rotary drum and have different azimuth
angles, and data are reproduced from tracks by said heads, wherein
said method comprises format steps in which a normal data area
which is used in normal speed reproduction, and one or more search
data areas which are used in search speed reproduction are disposed
in each track, said tracks are divided into track sets having a
plurality of tracks, said search data areas of the track set are
disposed at a position of each track which is separated from the
edge of a tape by a predetermined distance, and the same data are
disposed in said search data areas of the track set, positional
relationships between the track and said heads are controlled in
search speed reproduction at a reference speed for search speed
reproduction, and data of said search data areas of the track set
are reproduced by plural scans of said heads.
33. A recording and reproducing method according to claim 32,
wherein the reference speed for search speed reproduction is
(N.sub.3+0.5)-fold speed (where N.sub.3 is a positive integer), and
said method further comprises a format step in which tracks are
divided into track sets having (2.times.N.sub.3+1) or more tracks
which are alternately selected.
34. A recording and reproducing method according to claim 33,
wherein said method further comprises a format step in which said
search data areas are disposed on a track along which said heads
scan in (2.times.N.sub.3)-fold speed reproduction, and positional
relationships between the track and said heads are controlled in
(2.times.N.sub.3)-fold speed search speed reproduction and data of
said search data areas are reproduced.
35. A recording and reproducing method according to claim 32,
wherein two or more heads have at least one of the azimuth angles,
the reference speed for search speed reproduction is N.sub.1-fold
speed (where N.sub.1 is a positive odd number), and said method
further comprises a format step in which tracks are divided into
track sets having N.sub.1 or more tracks which are alternately
selected.
36. A recording and reproducing method according to claim 35,
wherein said search data areas are disposed on a track along which
said heads scan in (2.times.N.sub.1)-fold speed reproduction, and
said method further comprises a format step in which positional
relationships between the track and said heads are controlled in
(2.times.N.sub.1)-fold speed search speed reproduction and data of
said search data areas are reproduced.
37. A recording and reproducing method according to claim 32,
wherein the reference speed for search speed reproduction is
N.sub.4-fold speed (where N.sub.4 is a positive even number), and
said method further comprises a format step in which tracks are
divided into track sets having (2.times.N.sub.4) or more continuous
tracks.
38. A recording and reproducing method according to claim 37,
wherein said method further comprises a format step in which said
search data areas are disposed on a track along which said heads
scan in (2.times.N.sub.4-1)-fold speed reproduction, and positional
relationships between the track and said heads are controlled in
(2.times.N.sub.4-1)-fold speed search speed reproduction and data
of said search data areas are reproduced.
39. A recording and reproducing method in which data are
sequentially recorded in adjacent tracks by a plurality of heads
which are mounted on a rotary drum and have different azimuth
angles, and data are reproduced from tracks by said heads, wherein
said method comprises format steps in which a normal data area
which is used in normal speed reproduction, and one or more search
data areas which are used in search speed reproduction are disposed
in each track, said tracks are divided into track sets having a
plurality of tracks, said search data areas of the track set are
disposed at a position of each track which is separated from the
edge of a tape by a predetermined distance, the same data are
disposed in said search data areas of the track set, and a part or
the whole of data are recorded in the search data areas in a
repeated manner in a longitudinal direction of the track.
40. A recording and reproducing method in which data are
sequentially recorded in adjacent tracks by a plurality of heads
which are mounted on a rotary drum and have different azimuth
angles, and data are reproduced from tracks by said heads, wherein
said method comprises format steps in which a normal data area
which is used in normal speed reproduction, and one or more search
data areas which are used in search speed reproduction are disposed
in each track, said tracks are divided into track sets having a
plurality of tracks, said search data areas of the track set are
disposed at a position of each track which is separated from the
edge of a tape by a predetermined distance, and the same data are
disposed in said search data areas of the track set, and, in search
speed reproduction, data of said search data areas of the track set
are reproduced by W or more scans (where W is an integer which is
not less than 3).
41. A recording and reproducing method in which data are
sequentially recorded in adjacent tracks by a plurality of heads
which are mounted on a rotary drum and have different azimuth
angles, data are reproduced from tracks by said heads, and a
control signal is recorded and reproduced in a longitudinal
direction of a tape, wherein said method comprises format steps in
which a normal data area which is used in normal speed
reproduction, and one or more search data areas which are used in
search speed reproduction are disposed in each track, said tracks
are divided into track sets having a plurality of tracks, said
search data areas of the track set are disposed at a position of
each track which is separated from the edge of the tape by a
predetermined distance, and the same data are disposed in said
search data areas of the track set, and delimitation of the track
set is indicated by the control signal.
42. A recording and reproducing method in which data are
sequentially recorded in adjacent tracks by a plurality of heads
which are mounted on a rotary drum and have different azimuth
angles, and data are reproduced from tracks by said heads, wherein
said method comprises format steps in which a normal data area
which is used in normal speed reproduction, and one or more search
data areas which are used in search speed reproduction are disposed
in each track, and an AUX area is disposed in a part of said search
data areas.
43. A search speed reproducing method in which reproduction is
conducted at a speed which is different from a tape speed in
record, by using a plurality of heads which are mounted on a rotary
drum and have the same azimuth angle, wherein data are reproduced
from a track which is recorded on a tape by at least two heads
which are mounted on said rotary drum to be opposed each other at a
central angle of 180 deg. and which have the same azimuth
angle.
44. A reproducing method in which data are reproduced from a tape
in which tracks of different azimuth angles are alternately
arranged, a normal data area which is used in normal speed
reproduction, and one or more search data areas which are used in
search speed reproduction are disposed in each track, said tracks
are divided into track sets having a plurality of tracks, said
search data areas of the track set are disposed at a position of
each track which is separated from the edge of a tape by a
predetermined distance, and the same data are disposed in said
search data areas of the track set, wherein, in search speed
reproduction at a reference speed for search speed reproduction,
positional relationships between the track and said heads are
controlled, and data of said search data areas of the track set are
reproduced by plural scans of said heads.
45. A reproducing method in which data are reproduced from a tape
in which tracks of different azimuth angles are alternately
arranged, a normal data area which is used in normal speed
reproduction, and one or more search data areas which are used in
search speed reproduction are disposed in each track, said tracks
are divided into track sets having a plurality of tracks, said
search data areas of the track set are disposed at a position of
each track which is separated from the edge of the tape by a
predetermined distance, and the same data are disposed in said
search data areas of the track set, wherein, in search speed
reproduction, data of said search data areas of the track set are
reproduced by W or more scans (where W is an integer which is not
less than 3).
Description
[0001] 1. FIELD OF THE INVENTION
[0002] The present invention relates to a recording or reproducing
apparatus of the rotary head type which can magnetically record a
digital signal, and more particularly to a digital VCR (Video
Cassette Recorder) which can record and reproduce plural signals of
different data rates and surely reproduce data even when data are
searched at a high speed.
[0003] 2. DESCRIPTION OF THE RELATED ART
[0004] Conventionally, as a method of recording and reproducing
plural signals of different data rates in a VCR, known is a method
which is described in a publication of IEEE Transactions on
Consumer Electronics, Vol. 40, No. 3, P. 263-268. This publication
shows a technique of conducting multirate recording in a digital
VCR without changing a recording density.
[0005] In the method, two heads of different azimuth angles are
mounted on a rotary drum so as to be opposed to each other at a
central angle of 180.degree.. These heads are called a first head
and a second head, respectively. When the rotary drum rotates, the
first and second heads alternately scan a tape. Hereinafter, the
description is made only on the recording operation. The
reproducing operation is conducted in the same manner.
[0006] In normal record and reproduction (1-speed record and
reproduction) in which an image is recorded and reproduced at a
normal speed, a magnetic tape (hereinafter, referred to as merely
"tape") is caused to run at a predetermined speed (1-speed). First,
the first head scans the tape, and the second tape then scans the
tape so that signals are sequentially recorded.
[0007] In the 1/3-speed record and reproduction mode (1/3-speed
record and reproduction) in which the rate of data to be recorded
is one third that of the normal record and reproduction, the tape
speed is reduced to 1/3. First, the first head scans the tape and
records a signal. Next, the second head scans the tape and the
first head then conducts the second scan. In the scan of the second
head and the second scan of the first head, a signal is not
recorded. When the second head then scans the tape, a signal is
recorded. Similarly, when the first and second heads then scan the
tape in sequence, a signal is not recorded. In the next scan of the
first head, a signal is recorded. Then, the operation state returns
to the initial state. The recording at the 1/3-data rate is
conducted by repeating the above operation. In a similar manner, a
signal can be recorded and reproduced at a 1/n data rate (where n
is a positive odd number).
[0008] In addition to the configuration, a third head of an azimuth
angle which is different from that of the first head may be
colocated or placed at the same position so that, even when n is an
even number, record and reproduction are enabled. Since the first
and third heads are colocated, the scan operations conducted by the
two heads are substantially coincident with each other.
[0009] When a signal of the data rate which is one half that of the
normal record and reproduction is to be recorded and reproduced,
for example, record and reproduction are conducted in the following
manner. First, the tape speed is reduced to one half that of normal
speed reproduction. When the first and third heads scan the tape,
the first head conducts the signal recording but the third head
does not conduct it. When the first and third heads scan the tape
at the next time, the third head conducts signal record but the
first head does not conduct it. Signal record at the 1/2-fold data
rate is conducted by repeating the operation.
[0010] Even when n is a positive even number, signals can be
generally recorded and reproduced at a 1/n-fold data rate in a
similar manner.
[0011] In such a prior art recording and reproducing apparatus, the
first and third heads are to be colocated. Actually, however, it is
difficult to dispose two heads at the same position, and hence the
two heads are located at positions which are close to each other,
respectively.
[0012] However, a prior art magnetic recording and reproducing
apparatus is not provided with a measure against a problem which
may be produced by the close arrangement of two heads. As a result,
there arise problems in that the track width varies because the
tape speed is changed in record modes of different data rates, and
that the tracking margin which is tolerance for deviation of a head
is reduced in search speed reproduction in which reproduction is
conducted at a speed different from the normal one.
[0013] Conventionally, as a method of conducting search speed
reproduction in a digital VCR, known is a method disclosed in
Japanese Patent Publication (Kokai) No. HEI 2-94071.
[0014] In the disclosed method, when a video signal is to be
recorded, a subcode area is formed on a tape. The subcode area is
formed on the scanning locus of a head which is to be produced in
search speed reproduction, and still image information extracted
from the video signal is recorded in the subcode area in a
distributed manner. In search speed reproduction, data recorded in
the subcode area are reproduced so as to reproduce the still image
information, thereby improving the image quality of variablespeed
reproduction.
[0015] In such a configuration, however, a speed at which still
image information can be stably reproduced in search speed
reproduction is restricted only to one kind. In a VCR at present, a
speed of one kind is not sufficient for search speed reproduction.
According to the prior art method, in order to cope with plural
variable reproduction speeds, data must be recorded in a duplicate
manner on all the scanning loci of heads which are to be produced
in the plural variable reproduction speeds. This produces problems
in that duplication of data is required so that reproduction of
data is complicated, and that data are wasted.
[0016] In the prior art method, the record track must be made
positionally coincident with the heads. Furthermore, the track in
which the subcode area is formed must be selected in search speed
reproduction, thereby producing a problem in that the mode shift
from normal speed reproduction in which an image is reproduced at
the normal speed to search speed reproduction requires a prolonged
time period. In the prior art method, there is a further problem in
that an AUX area in which additional information such as a program
is to be recorded is disposed in the normal data area and hence
information of the AUX area cannot be reproduced in search speed
reproduction.
OBJECT AND SUMMARY OF THE INVENTION
[0017] It is an object of the present invention to suppress the
variation in track width when plural signals of different data
rates are recorded.
[0018] It is another object of the invention to reduce the failure
in obtaining search information and surely reproduce search data in
search speed reproduction.
[0019] The present invention is to easily realize search speed
reproduction of a high image quality in a simple data
arrangement.
[0020] The present invention is to reduce wasted search data and
realize search speed reproduction of plural speeds.
[0021] The present invention is to provide a recording and
reproducing apparatus which can surely reproduce search data even
when the phase indicative of positional deviation between a head
and a record track is not controlled in search speed
reproduction.
[0022] The present invention is to provide a recording and
reproducing apparatus in which it is not required to select a track
to be scanned in search speed reproduction and the mode can be
smoothly shifted from normal speed reproduction to search speed
reproduction.
[0023] The present invention is to provide a recording and
reproducing apparatus in which evena head of a width substantially
equal to a track pitch can reproduce all effective search data.
[0024] The present invention is to provide a recording and
reproducing apparatus which can reproduce information of an AUX
area also in search speed reproduction.
[0025] In order to attain the objects, the recording and
reproducing apparatus of the invention comprises: tape driving
means for driving a tape; a rotary drum around which the tape is to
be slantly wound; three heads, first, second, and third heads which
are mounted on the rotary drum and which scan the tape so as to
conduct recording or reproducing operation; and a head control unit
which controls the operations of the three heads. The azimuth
angles of the three heads are set so that the first head has a
first azimuth angle and the second and third heads have a second
azimuth angle which is different from the first azimuth angle. The
three heads have mutual positional relationships in which the first
and second heads are mounted on the rotary drum so as to be opposed
each other at a central angle of 180.degree. and at the same
height. in the rotation shaft direction of the rotary drum, and the
third head is located in close proximity to the first head in the
circumferential direction of the rotary drum with a minute
difference in central angle and a minute height differencein the
rotation shaft direction of the rotary drum.
[0026] According to this configuration, the minute height
difference is set between the first and third heads which are
disposed in close proximity to each other. When plural signals of
different data rates are to be recorded or reproduced, therefore,
the head scan error can be reduced and the variation in record
track width can be minimized.
[0027] In order to attain the objects, the apparatus of the
invention comprises a rotary drum around which a tape is to be
slantly wound, and three heads, first, second, and third heads
which are mounted on the rotary drum and scan the tape so as to
conduct recording or reproducing operation. The azimuth angles of
the three heads are set so that the first head has a first azimuth
angle and the second and third heads have a second azimuth angle
which is different from the first azimuth angle. The three heads
have mutual positional relationships in which the second and third
heads are mounted on the rotary drum so as to be opposed each other
at a central angle of 180 deg. and the first head is located in
close proximity to the third head in the circumferential direction
of the rotary drum with a minute difference in central angle.
[0028] According to this configuration, since the second and third
heads having the same azimuth angle (the second azimuth angle) are
located at positions which are opposed to each other at a central
angle of 180.degree., the deviation amount in scan position of the
heads in search can be reduced and made always constant
irrespective of the search speed. Even in a high speed search,
therefore, search data can be surely reproduced.
[0029] In order to attain the objects, a plurality of heads having
at least one azimuth angle are disposed. A normal data area used in
normal speed reproduction which is reproduction conducted at the
normal speed, and one or more search data areas used in search
speed reproduction are disposed in one track. The reference speed
for search speed reproduction which is a speed serving as the
reference for search speed reproduction is set to be N.sub.1
[N.sub.1-speed] (where N.sub.1 is an odd number). The search data
areas of a track set consisting of N.sub.1 or more tracks which are
alternately selected are disposed at positions of the respective
tracks and on the same line parallel to the tape running direction.
The same data are recorded in the search data areas of the track
set.
[0030] According to this configuration, each of the plurality of
heads scans one time the track set, and hence it is not required to
select the track to be selected. Even when the positional
relationships between the heads and record tracks are not
controlled, moreover, data can be complementarily reproduced by
plural scans or all effective data of the search data areas can be
reproduced by either of plural scans. Therefore, search speed
reproduction of a high image quality can be realized in a simple
data arrangement.
[0031] In order to attain the objects, a normal data area which is
used in normal speed reproduction, and one or more search data
areas which are used in search speed reproduction are disposed in
one track. The reference speed for search speed reproduction is
set. The search data areas of a track set consisting of a plurality
of tracks are disposed at positions on the same line parallel to
the tape running direction on the respective tracks. The search
data areas of the track set have the same data. In reproduction at
the reference speed for search speed reproduction, the positional
relationships between tracks and the heads are controlled, and data
of the search data areas of the track set are reproduced by two
scans of the heads.
[0032] According to this configuration, the heads scan the search
data areas two times in complementary positional relationships and
hence all effective data of the search data areas can be
complementarily reproduced. Therefore, it is not required to select
a track to be scanned so that even heads which have the width
substantially equal to the track pitch or a small tracking margin
can realize search speed reproduction of a high image quality.
[0033] In order to attain the objects, when reproduction is to be
conducted at a reproduction speed which is about two times the
reference speed for search speed reproduction, a search data area
is formed on a locus along which a head scans a tape, and, when
reproduction is to be conducted at the reference speed for search
speed reproduction, data of the search data area are reproduced by
two scans of the head.
[0034] According to this configuration, even when a track to be
scanned is not selected, reproduction can be conducted at the
reference speed for search speed reproduction and a speed which is
about two times the reference speed. Furthermore, all search data
can be reproduced by heads which have the width substantially equal
to the track pitch. As a result, the same data are commonly used in
reproductions of different speeds, and hence it is possible to
realize search speed reproductions of different speeds in which
search data are not duplicately used.
[0035] In order to attain the objects, a normal data area which is
used in normal speed reproduction, and one or more search data
areas which are used in search speed reproduction are disposed in
one track. The search data areas of a track set consisting of a
plurality of tracks which are alternately selected are disposed at
positions on the same line of the respective tracks. The same data
are recorded in the search data areas of the track set. Data of the
search data areas are reproduced by W scans (where W is an integer
which is 3 or more).
[0036] According to this configuration, even when heads which have
the width substantially equal to the track pitch are used in search
speed reproduction, all effective data of the search data areas can
be reproduced by W scans without requiring the control of the
positional relationships between the heads and record tracks.
Consequently, search speed reproduction of plural speeds in which
wasted search data are reduced can be realized.
[0037] In order to attain the objects, a normal data area which is
used in normal speed reproduction, and one or more search data
areas which are used in search speed reproduction are disposed in
one track. The search data areas of a track set consisting of a
plurality of tracks which are alternately selected are disposed at
positions on the same line parallel to the tape running direction
on the respective tracks. The same data are recorded in the search
data areas of the track set. The delimitation of the track set is
indicated by the control signal.
[0038] According to this configuration, the detection of a track
set can be simplified and it is not required to record data
indicative of the delimitation of a track set, whereby search speed
reproduction of a high image quality can be easily realized.
[0039] In order to attain the objects, a normal data area which is
used in normal speed reproduction, and one or more search data
areas which are used in search speed reproduction are disposed in
one track. An AUX area is formed in a part of the search data
areas.
[0040] According to this configuration, data recorded in the AUX
area can be reproduced in both normal speed reproduction and search
speed reproduction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1 is a block diagram of a recording and reproducing
apparatus of a first embodiment of the invention;
[0042] FIG. 2 is a plan view of a rotary drum showing the head
arrangement in the first embodiment of the invention;
[0043] FIG. 3 is a diagram showing a height difference of heads
mounted in the first embodiment of the invention;
[0044] FIG. 4 is a track pattern diagram of a magnetic tape;
[0045] FIG. 5A is a time chart of input signals in the first
embodiment of the invention;
[0046] FIG. 5B is a time chart of the recording operation conducted
when N=1 in the first embodiment of the invention;
[0047] FIG. 5C is a time chart of the recording operation conducted
when N=2 in the first embodiment of the invention;
[0048] FIG. 5D is a time chart of the recording operation conducted
when N=3 in the first embodiment of the invention;
[0049] FIG. 5E is a time chart of the recording operation conducted
when N=4 in the first embodiment of the invention;
[0050] FIG. 6 is a plan view of a tape showing the head scan
error;
[0051] FIG. 7 is a plan view of a tape showing deviation of a head
position;
[0052] FIG. 8 is a block diagram of a recording and reproducing
apparatus of a second embodiment of the invention;
[0053] FIG. 9 is an arrangement diagram showing a height difference
of heads mounted in the second embodiment;
[0054] FIG. 10 is a timing chart of the operation of the second
embodiment;
[0055] FIG. 11 is a timing chart of the operation of the second
embodiment;
[0056] FIG. 12 is a plan view of a tape illustrating the search
operation of the second embodiment;
[0057] FIG. 13 is a graph showing relationships between search
speeds and scan positions in the first and second embodiments;
[0058] FIG. 14 is a diagram showing a height difference of heads
mounted in a third embodiment;
[0059] FIG. 15 is a block diagram of a recording and reproducing
apparatus of a fourth embodiment of the invention;
[0060] FIG. 16 is a plan view of a tape showing the track pattern
in the fourth embodiment of the invention;
[0061] FIG. 17A is a plan view of a tape showing the track pattern
in the fourth embodiment of the invention;
[0062] FIG. 17B is a plan view of a tape showing search data areas
in the fourth embodiment of the invention in an enlarged
manner;
[0063] FIG. 17C is a plan view of a rotary drum showing the head
arrangement in the fourth embodiment of the invention;
[0064] FIG. 18A is a plan view of a tape showing the track pattern
in the fourth embodiment of the invention in the case where the
head width is greater than the track pitch;
[0065] FIG. 18B is a plan view of a tape showing search data areas
in the fourth embodiment of the invention in an enlarged manner in
the case where the head width is greater than the track pitch;
[0066] FIG. 19A is a plan view of a tape showing the track pattern
in the fourth embodiment of the invention in the case where search
data areas are disposed in tracks of R- and L-azimuth angles;
[0067] FIG. 19B is a plan view of the rotary drum showing the head
arrangement in the fourth embodiment of the invention in the case
where search data areas are disposed in tracks of R- and L-azimuth
angles;
[0068] FIG. 20A is a plan view of a tape showing a second example
of the track pattern in the fourth embodiment of the invention in
the case where search data areas are disposed in tracks of R- and
L-azimuth angles;
[0069] FIG. 20B is a plan view of the rotary drum showing a second
example of the head arrangement in the fourth embodiment of the
invention in the case where search data areas are disposed in
tracks of R- and L-azimuth angles;
[0070] FIG. 21 is a plan view of a tape showing the track pattern
in a fifth fourth embodiment of the invention;
[0071] FIG. 22A is a plan view of a tape showing the track pattern
in the fifth embodiment of the invention;
[0072] FIG. 22B is a plan view of a rotary drum showing the head
arrangement in the fourth embodiment of the invention;
[0073] FIG. 23A is a plan view of a tape showing the track pattern
in a sixth embodiment of the invention;
[0074] FIG. 23B is a plan view of a rotary drum showing the head
arrangement in the sixth embodiment of the invention;
[0075] FIG. 24 is a plan view of a tape in the case where scans of
search data areas are repeated in the longitudinal direction of a
track;
[0076] FIG. 25A is a plan view of a tape showing the track pattern
in the sixth embodiment of the invention in the case where search
data areas are disposed in tracks of R- and L-azimuth angles;
[0077] FIG. 25B is a plan view of the rotary drum showing the head
arrangement in the sixth embodiment of the invention in the case
where search data areas are disposed in tracks of R- and L-azimuth
angles;
[0078] FIG. 26A is a plan view of a tape showing the track pattern
in a seventh fifth embodiment of the invention;
[0079] FIG. 26B is a plan view of a rotary drum showing the head
arrangement in the seventh embodiment of the invention;
[0080] FIG. 27 is a plan view of a tape showing the track pattern
in an eighth embodiment of the invention;
[0081] FIG. 28A is a plan view of a tape showing the track pattern
in the eighth embodiment of the invention;
[0082] FIG. 28B is a plan view of a rotary drum showing the head
arrangement in the eighth embodiment of the invention;
[0083] FIG. 28C is a diagram showing positional relationships of
heads in the eighth embodiment of the invention;
[0084] FIG. 29 is a plan view of a tape showing the track pattern
in a ninth embodiment of the invention; and
[0085] FIG. 30 is a flow chart showing the recording operation of
the recording and reproducing apparatus of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0086] The present invention will be described in detail below with
reference to the accompanying drawings.
[0087] First Embodiment
[0088] A first embodiment of the present invention will be
described with reference to FIG. 1--FIG. 7.
[0089] Hereinafter, a first embodiment of the invention will be
described with reference to FIGS. 1 to 7.
[0090] A mode in which record or reproduction is conducted at the
reference tape speed (1-speed) is as a standard mode, and the data
rate of input and output in the standard mode is defined as the
reference data rate. A mode in which record or reproduction is
conducted at a tape speed which is one N-th the reference tape
speed is defined as an N-fold long-recording-time mode (where N is
a positive integer).
[0091] The first embodiment of the invention has the following
configuration. FIG. 1 is a block diagram, FIG. 2 is a plan view of
a rotary drum showing the head arrangement, and FIG. 3 is a diagram
showing a height difference of heads. In FIG. 3, the arrow S
indicates the upward direction in the rotation shaft direction of
the rotary drum 1.
[0092] A first head 2a, a second head 2b, and a third head 2c are
mounted on the circumference of the rotary drum 1. The heads 2a and
2c are mounted in close proximity to each other. The head 2c leads
the head 2a by a central angle .theta. in the rotation direction A
of the rotary drum 1. The head 2c is attached at a position which
is higher than the head 2a by a minute height difference H. The
heads 2a and 2b have a mutual positional relationship in which they
are opposed to each other at a central angle of 180.degree. and are
equal in height to each other. The heads 2b and 2c have the same
azimuth angle, and the head 2a has an azimuth angle which is
different from those of the heads 2b and 2c. Accordingly, it is
assumed that the head 2a has the L-azimuth angle and the heads 2b
and 2c have the R-azimuth angle.
[0093] A tape 5 is caused by a plurality of tape guides 6 to be
slantly wound around the rotary drum 1 over a central angle of
about 180.degree., and driven by a capstan 7 and a pinch roller 8
so as to run over the rotary drum. When the rotary drum 1 rotates,
the heads 2a, 2b, and 2c slantly scan the tape 5 and record or
reproduce tracks 9a and 9b on the tape 5. FIG. 4 shows the manner
of recording the track 9a by the head 2a. In the embodiment, the
rotation angle or effective winding angle of the rotary drum 1 for
forming the tracks 9a and 9b is, for example, a central angle of
174.degree..
[0094] The rotation speed of the capstan 7 is controlled by a
capstan control unit 10 so that the tape running speed in record
and reproduction is maintained to be one N-th the reference tape
speed. The reference tape speed is a speed at which the head scan
position is deviated in the track width direction by two track
pitches 2Tp during a period when the rotary drum 1 makes one
revolution. When the rotary drum 1 makes one half revolution, the
head scan position is deviated by one track pitch 1Tp. In record
and reproduction (other than search), the revolution number of the
rotary drum 1 is constant irrespective of the value of N. A head
control unit 11 controls the timing of record and reproduction and
comprises a head selection switch 12, a head amplifier 13, and a
signal processing unit 14.
[0095] The signal processing unit 14 adds synchronization
information, ID information (synchronization block number, etc.), a
header, an error correcting code, and the like to an input signal
15, thereby producing original record data. The original record
data are time-base-compressed into data for each track. The data
are amplified by the head amplifier 13 and then divided among the
heads 2a, 2b, and 2c by the head selection switch 12. Similarly,
reproduced signals from the heads 2a, 2b, and 2c are supplied to
the head amplifier 13 through the head selection switch 12 and then
transmitted to the signal processing unit 14. The signal processing
unit 14 conducts processes such as time-base-expansion of the
reproduced signals, removal of information added in recording
operation, and error correction and restores the signals to the
original data.
[0096] In the thus-configured recording and reproducing apparatus,
the operation in the N-fold long-recording-time mode will be
described.
[0097] When the revolution number of the rotary drum 1 is
represented by r(revolutions/second) and the time period required
for the rotary drum 1 to make one half revolution is represented by
.tau. (seconds), the relationship of .tau.=1/2r is established. The
time period required for each head to scan one track is indicated
by Tr. In this example, since one track is formed by rotating the
rotary drum by 174.degree., the time period Tr is 174.tau./180
(seconds).
[0098] For the sake of description, as shown in FIG. 5A, the
original record data are divided every r seconds so as to be
indicated as data blocks D1, D2, . . . . When the magnification N
is 1 or the standard mode is set, one data block is used as data
for one track.
[0099] In the N-fold long-recording-time mode, N data blocks are
recorded in one track.
[0100] The amount of data which are to be recorded in one track 9
is constant irrespective of the magnification N. The amount of data
included in one data block in the N-fold long-recording-time mode
is one N-th that of data included in one data block in the standard
mode. Consequently, the data rate in the N-fold long-recording-time
mode is the reciprocal of the magnification N in the standard
mode.
[0101] The signal processing unit 14 conducts the data conversion
processing on the input signal 15. First, the input signal 15 is
subjected to processes such as addition of an error correcting code
and original record data blocks D1, D2, . . . are produced. The
original record data are combined in the unit of N data blocks and
time-base-compressed so that record data for one track DR1, DR2,
are sequentially produced. Since each set of the record data
contains original record data for N data blocks, record data for
one track are produced for a time period N.tau.. The record data
are recorded into one track 9 for each time period N.tau.. In the
above, .tau. indicates the time period required for the rotary drum
1 to make one half revolution. Consequently, one track 9 is
recorded for every N/2 revolutions. Since the tape speed is one
N-th the reference tape speed, the head scan position is deviated
by Tp/N as a result of one half revolution of the rotary drum 1 and
by 2Tp/N as a result of one revolution. Namely, the head scan
position is deviated by one track pitch 1Tp as a result of N/2
revolutions of the rotary drum 1. When record is conducted for
every N/2 revolutions, therefore, it is possible to obtain a normal
track pattern.
[0102] In the azimuth record, heads of different azimuth angles or
L- and R-azimuth angles alternately conduct record or reproduction.
When the magnification N is an odd number, record is conducted for
every N/2 revolutions and hence the heads 2a and 2b which are
opposed to each other at a central angle of 180.degree. on the
rotary drum 1 are used. When the magnification N is an even number,
N/2 is an integer. Strictly speaking, therefore, heads which are at
the same position on the rotary drum 1 must be used. In order to
conduct the azimuth record, however, the heads 2a and 2c which are
in close proximity to each other are used.
[0103] When the magnification N is an odd number, the head
selection switch 12 switches over the connections between the head
amplifier 13 and the heads 2a and 2b for every N/2 revolutions of
the rotary drum 1, and is closed only for a time period Tr when
each of the heads 2a and 2b scans the tape 5 so as to connect the
head 2a or 2b to the head amplifier 13. When the magnification N is
an even number, the head selection switch 12 switches over the
connections between the head amplifier 13 and the heads 2a and 2c
for every N/2 revolutions of the rotary drum 1, and is closed only
for a time period Tr when each of the heads 2a and 2c scans the
tape 5 so as to connect the head 2a or 2c. In accordance with the
switching operation of the head selection switch 12, the signal
processing unit 14 outputs the record data DR1, DR2, . . . in
sequence. The record data DR1, DR2, . . . are amplified by the head
amplifier 13 and then recorded onto the tape 5 by the head 2a, 2b,
or 2c.
[0104] As a result of the recording operation described above, the
record in the N-fold long-recording-time mode can be conducted at a
speed which is one N-th the reference tape speed. At this time, the
data rate is one N-th the reference data rate.
[0105] In reproduction, the head selection switch 12 operates in
the same manner as the case of record. Signals reproduced in the
head unit are amplified by the head amplifier 13, subjected to
processes such as error correction in the signal processing unit
14, and then time-base-expanded to data of N.times..tau. seconds so
as to be restored to the original data blocks D1, D2, . . . .
[0106] As described above, in the N-fold long-recording-time mode,
signals can be recorded or reproduced at the data rate of 1/N. Also
in the standard mode (N=1), record and reproduction are conducted
in a similar manner.
[0107] These operations will be described specifically in the cases
wherein record is conducted in the magnification N=1, 2, 3, or 4,
with reference to the accompanying drawings.
[0108] FIG. 5A shows the original record data which are partitioned
at intervals of seconds and in the form of the data blocks D1, D2,
. . . . In FIGS. 5B to 5E, boxes indicated by broken lines show
periods when data are nor recorded.
[0109] FIG. 5B shows the recording operation conducted when the
magnification N=1. Since the magnification N is an odd number, the
head selection switch 12 switches over the heads 2a and 2b so that
the heads 2a and 2b are used in record or reproduction. Since the
heads 2a and 2b have the mutual positional relationship in which
they are opposed to each other at a central angle of 180.degree.,
the heads alternately scan the tape 5 for every one half revolution
of the rotary drum 1. The original record data blocks D1, D2, . . .
are processed in the signal processing unit into the record data
DR1, DR2, . . . , and then alternately recorded by the head 2a or
2b for every one half revolution (=N/2 revolutions).
[0110] FIG. 5C shows the recording operation conducted when the
magnification N=2. Since the magnification N is an even number, the
head selection switch 12 switches over the heads 2a and 2c so that
the heads 2a and 2c are used in record or reproduction. Since the
heads 2a and 2c are disposed in close proximity to each other, the
heads scan the tape 5 at the substantially same timing for every
one revolution of the rotary drum 1. The original record data
blocks D1, D2, . . . are processed in the signal processing unit 14
into the record data DR1, DR2, . . . respectively corresponding to
two data blocks. The record data DR1 are data of the combination
(D1+D2) of data blocks, and the record data DR2 . . . are data of
the combination (D3+D4) . . . of data blocks. The record data are
then alternately recorded by the head 2a or 2c for every one
revolution (=N/2 revolutions).
[0111] FIG. 5D shows the recording operation conducted when the
magnification N is 3. Since N is an odd number, the head selection
switch 12 switches over the heads 2a and 2b so that the heads 2a
and 2b are used in record or reproduction. Since the heads 2a and
2b have the mutual positional relationship in which they are
opposed to each other at a central angle of 180.degree., the heads
alternately scan the tape 5 for every one half revolution of the
rotary drum 1. The original record data blocks D1, D2, . . . are
processed in the signal processing unit 14 into the record data
DR1, DR2, . . . respectively corresponding to three data blocks.
The record data DR1 are data of the combination (D1+D2+D3) of data
blocks and the record data DR2 are data of the combination
(D4+D5+D6) of data blocks. The record data are then alternately
recorded by the head 2a or 2b for every one and a half revolutions
(=N/2 revolutions) of the rotary drum 1.
[0112] FIG. 5E shows the recording operation conducted when the
magnification N is 4. Since the magnification N is an even number,
the head selection switch 12 switches over the heads 2a and 2c so
that the heads 2a and 2c are used in record or reproduction. Since
the heads 2a and 2c are disposed in close proximity to each other,
the heads scan the tape 5 at the substantially same timing for
every one revolution of the rotary drum 1. The original record data
blocks D1, D2, . . . are processed in the signal processing unit 14
into the record data DR1, DR2, respectively corresponding to four
data blocks. When the record data DR1, DR2, . . . are indicated by
using a suffix n or a general formula DRn, the record data DRn are
data of the combination (D(4n-3)+D(4n-2)+D(4n-1)+- D(4n)) of data
blocks. The record data are then alternately recorded by the head
2a or 2c for every two revolutions (=N/2 revolutions) of the rotary
drum 1.
[0113] The time period Tr in FIGS. 5A to 5E indicates the time
period required for the head 2a, 2b, or 2c to scan one track of the
tape 5.
[0114] In the above, the recording operations in the cases where
the magnification N is 1, 2, 3, or 4 have been described with
reference to FIGS. 5A to 5E. As described above, the reproducing
operation is conducted in a similar manner. In reproduction,
reproduced data for one track are time-base-expanded in the signal
processing unit 14 to data of N.times..tau. seconds and then
restored to the original data by conducting processes such as error
correction and removal of information added in recording operation
Hereinafter, the height difference between the heads 2a and 2c will
be discussed. The heads 2a and 2c are separated from each other by
the central angle .theta., and the head 2c leads the head 2a in the
rotation direction of the rotary drum 1. When the magnification N
is an even number, the heads 2a and 2c alternately conduct record
or reproduction for every N/2 revolutions. Strictly speaking, the
heads 2a and 2c are not at the same position. Consequently, the
start of the scanning operation of the head 2c is earlier than that
of the head 2a by the time period corresponding to revolution of
the angle .theta. of the rotary drum 1. In consideration of the
distance in which the tape 5 runs for the time period, therefore,
the head 2c must be upward deviated in height from the head 2a.
This will be described below in more detail.
[0115] FIG. 6 shows the tape 5 which is wound around the rotary
drum 1, in a developed manner. It is assumed that the heads 2a and
2c in FIG. 6 are attached without height difference. When the
rotary drum 1 rotates, the heads moves in vector Vh. On the other
hand, the tape 5 also runs in vector VT. As a result, the tape 5
and the head 2c relatively move as indicated by an arrow Vb' in
FIG. 6. Similarly, the tape 5 and the head 2a relatively move as
indicated by an arrow Va' in FIG. 6. The arrows Va' and Vb' show
the scanning loci of the heads 2a and 2c, respectively. As shown in
FIG. 6, "deviation" is produced between the scanning loci. This
deviation is called a head scan error 16. In contrast, when a
height difference is previously formed as shown in FIG. 7, the head
scan error 16 can be canceled to be zero. The height difference of
heads which is formed for preventing the head scan error 16 from
occurring when record or reproduction is conducted at a 1/N-fold
speed is called the necessary height difference .DELTA.S(N).
[0116] The necessary height difference .DELTA.S(N) is obtained in
the following manner. At the reference tape speed, during a period
when the rotary drum 1 makes one revolution, the head scan position
is deviated by two track pitches 2Tp in the track width direction.
During a period when the rotary drum 1 makes a revolution of the
angle .theta., therefore, the head scan position is deviated by
Tp.times..theta./180. In a 1/N long-recording-time mode, the tape
speed is lowered to one Nth, therefore, the head scan position is
deviated by Tp.times..theta./(180.ti- mes.N) during a period when
the rotary drum 1 makes a revolution of the angle .theta..
Consequently, the head scan error 16 can be canceled by previously
forming a height difference corresponding to the deviation, between
the heads 2a and 2c. Therefore, the necessary height difference
.DELTA.S(N) is Tp.times..theta./(180.times.N). In actual heads, an
error corresponding to the difference between the minute height
difference H among the heads and the necessary height difference
.DELTA.S(N) is produced in the head scan position. This error
causes the head scan error 16.
[0117] If the minute height difference H among the heads is
identical with the necessary height difference .DELTA.S(N) have the
same value, the head scan error 16 can be eliminated. However, it
is impossible to set the minute height difference H among the heads
so as to be identical with the necessary height difference
.DELTA.S(N) in a plurality of magnifications N (even numbers),
because the necessary height difference .DELTA.S(N) varies
depending on the magnification N. When the magnification N is 2,
the necessary height difference .DELTA.S(2) is
Tp.times..theta./360. As the magnification N is larger, the more
the necessary height difference .DELTA.S(N) approaches zero.
Generally, the number of magnifications N is finite. The
magnifications N may be 1 and 2 only. Alternatively, the
magnifications N may be 3 in kind or 1, 2, and 8. In the former
case, when the minute height difference H is .DELTA.S(2), the head
scan error 16 can be made zero. In the latter case, in order to
minimize the head scan error 16, the minute height difference H is
set to be (.DELTA.S(2)-.DELTA.S(8))/2.
[0118] In the case where the magnification N is 1, 2, . . . , or N,
generally, as the magnification N is larger, the more the minute
height difference .DELTA.S(N) approaches zero. In order to reduce
the head scan error 16, therefore, the minute height difference H
is set to be .DELTA.S(2)/2. When the minute height differences H
among the heads are set in the range which satisfies
.DELTA.S(2)/2.ltoreq.minute height difference H.ltoreq.S(2), i.e.,
Tp.times..theta./720.ltoreq.minute height difference
H.ltoreq.Tp.times..theta./360, therefore, it is possible to reduce
the head scan error 16. According to this setting, for all the
magnifications N, the head scan error 16 is not greater than
Tp.times..tau./360. In a calculation example in which the track
pitch Tp is 9 .mu.m and the central angle .theta. is 10.degree.,
the head scan error 16 is 0.25 .mu.m or less. The head scan error
16 appears in the form of variation in track width. The difference
between track widths 9a and 9b is twice the head scan error 16. In
the term of the track pitch ratio, the difference is about 5% or
less. This value is not greater than one half that obtained in the
case where, for example, the heads 2a and 2c are mounted at the
same height. In this way, the minute height difference H between
the heads 2a and 2c is set to be in the above-mentioned range, and
hence the head scan error 16 can be reduced with the result that
the variation in record track width can be minimized.
[0119] As seen from the above description, the invention can
provide a recording and reproducing apparatus in which the problem
in that the track width is caused to vary by the distance between
the heads 2a and 2c which are disposed in close proximity to each
other can be prevented from arising.
[0120] In the embodiment, the minute height difference H between
the heads 2a and 2c is formed in such a manner that the head 2c is
placed at an upper position. As apparent from the description of
the embodiment, the direction of the minute height difference H to
be formed depends on the direction of the relative movement of the
tape 5 and the heads 2 and also on whether the head 2a leads or
lags. In accordance with the direction of the minute height
difference, the positional relationship between the heads 2a and 2c
is determined. In other words, the positional relationships between
the heads are variously determined depending on the manner of
executing the invention. The scope of the invention is not
restricted by the embodiment.
[0121] In the embodiment, the heads 2a and 2c are disposed in close
proximity to each other, and the head 2c which is used only when
the magnification N is an even number is placed so as to lead the
head 2a in the rotation direction of the rotary drum 1. In
contrast, the head 2c may lag the head 2a as far as the heads 2a
and 2c are disposed in close proximity to each other.
[0122] In the embodiment, the number of the mounted heads 2 is
three. Alternatively, the number of the heads may be four as far as
three heads among them operate in accordance with the invention.
For example, an erasing head and a tracking head may be added so as
to obtain a configuration in which four or more heads are
mounted.
[0123] The apparatus of the embodiment conducts record and
reproduction. Alternatively, the apparatus may be configured as an
apparatus dedicated to record or reproduction. The apparatus may
operate in accordance with the invention only in record, and in
another manner in reproduction. For example, a tape on which record
has been conducted at a 1/N-fold speed may be subjected to
reproduction at a speed higher or lower than that in the record so
that the data rates of the record and reproduction are different
from each other.
[0124] As seen from the description of the embodiment, the head 2c
is used only when the magnification N is an even number. The
invention may be modified so that the magnification N is restricted
to an odd number and the head 2c is not disposed.
[0125] In the embodiment, the input signal 15 is continuously
input. When the input signal 15 is not continuous, a countermeasure
may be taken so that a circuit which temporarily stores the input
signal 15 and converts it into a continuous signal is connected.
Therefore, the input signal 15 is not required to be always a
continuous signal.
[0126] In the embodiment, the data rate in the N-fold
long-recording-time mode is one N-th the reference data rate. This
means that the data rate of original record data including
additional record information such as synchronization information,
ID information, a header, and an error correcting code is one N-th
that of the standard mode. The data rate of the input signal 15 is
not required to be always one N-th that of the standard mode. When
the amount of additional record information is sufficiently smaller
than an input signal, for example, the data rate of the input
signal 15 is required to be equal to or less than about one N-th
the input signal 15 of the standard mode. Generally, the data rate
of the original record data is required not to be larger than about
one N-th the standard mode and not necessary to be constant. In
this case, the data rate of the original record data is converted
to one N-th the standard mode by, for example, conducting a data
rate conversion processing such as that meaningless data are
inserted into the data area of the original record data.
[0127] In the embodiment, the signal processing unit 14 adds
synchronization information, ID information, a header, an error
correcting code, and the like to the input signal 15, thereby
producing original record data, and then time-base-compresses the
original record data so as to produce record data for each track.
Record data for each track may be produced by time-base-compressing
the input signal 15 in the unit of, for example, data for about one
track, and then adding synchronization information, ID information,
a header, an error correcting code, and the like.
[0128] As seen from the above description, the invention can attain
the following effects.
[0129] When a signal of the data rate which is one N-th the
standard mode is to be recorded or reproduced, the minute height
difference H between the heads 2a and 2c which are disposed in
close proximity to each other is set to be
TP.times..theta./(180.times.N), whereby the head scan error 16 can
be made zero. As a result, the variation in record track width can
be eliminated.
[0130] Since the minute height difference H between the heads 2a
and 2c which are disposed in close proximity to each other is set
to be in the range of Tp.times..theta./720.degree. minute height
difference H.ltoreq.Tp.times..theta./360.degree., the head scan
error 16 can be made small in a plurality of magnifications N, with
the result that the variation in record track width can be
minimized.
[0131] Second Embodiment
[0132] FIG. 8 is a block diagram showing the configuration of the
recording and reproducing apparatus of a second embodiment of the
invention.
[0133] In order to simplify the description of the second and
subsequent embodiments, it is assumed that the effective winding
angle of the tape 5 on the rotary drum 1 is a central angle of
180.degree..
[0134] Referring to FIG. 8, the tape 5 is wound around the rotary
drum 1. The first head 2a has a first azimuth angle (the L-azimuth
angle) and the second and third heads 2b and 2c have a second
azimuth angle (the R-azimuth angle). The tape 5 runs while being
sandwiched between the capstan 7 and the pinch roller 8. The
capstan 7 is controlled by the capstan control unit 10. The heads
2a, 2b, and 2c are connected to the head selection switch 12. The
head selection switch 12 is connected to the signal processing unit
14 through the head amplifier 13. A signal is input to or output
from the signal processing unit 14 through a digital signal input
and output terminal 17.
[0135] FIG. 9 is a diagram showing positions where the heads are
attached in the recording and reproducing apparatus of the second
embodiment of the invention. The arrow S indicates the upward
direction in the rotation shaft direction of the rotary drum 1. In
FIG. 9, the same components as those of FIG. 8 are designated by
the same reference numerals and their description is omitted.
Referring to FIG. 9, the heads 2b and 2c are attached to the rotary
drum 1 so as to be opposed to each other at a central angle of
180.degree.. The heads 2c and 2a are positioned in close proximity
to each other in the circumferential direction of the rotary drum 1
with a central angle difference .theta.. The heads 2b and 2a are
attached with a first minute height difference .DELTA.H1 in the
rotation shaft direction of the rotary drum 1 indicated by the
arrow S, and the heads 2c and 2a are attached with a second minute
height difference .DELTA.H2 in the rotation shaft direction of the
rotary drum 1.
[0136] The operation of the thus configured recording and
reproducing apparatus will be described with reference to FIGS. 8
and 9.
[0137] The recording and reproducing apparatus of the embodiment
has the standard mode and a long-recording-time mode in which the
record time is N times that of the standard mode (where N is a
natural number). The rotary drum 1 rotates at a constant speed
irrespective of the change of the mode. The tape 5 is slantly wound
around the rotary drum 1 over a central angle of 180.degree. and
odd, and driven at a predetermined speed by the capstan 7 and the
pinch roller 8. The capstan control unit 10 controls the rotation
speed of the capstan 7 so that, in an N-fold long-recording-time
mode, the tape runs at a constant speed which is one N-th the
standard mode. At the timing conforming to the modes, the head
selection switch 12 selects the head which is to conduct record or
reproduction. The head amplifier 13 amplifies a record or
reproduced signal.
[0138] In a long-recording-time mode, the signal processing unit 14
conducts processes such as compression coding of a signal,
expansion decoding, time-base-compression/expansion, and error
correction. Specifically, in record of an N-fold
long-recording-time mode, a digital signal supplied to the digital
signal input and output terminal 17 is subjected in the signal
processing unit 14 to data compression to the magnification 1/N to
be coded, and time-base compression, and then supplied to the head
amplifier 13. In the embodiment, it is assumed that a signal to
which synchronization information, ID information, a header, an
error correcting code, and the like have already added is supplied
to the digital signal input and output terminal 17. Also in the
case where synchronization information, etc. are added in the
signal processing unit 14 in the same manner as the first
embodiment, the same effects as those of the present embodiment can
be attained by conducting signal processing so that the data rate
of record data containing synchronization information, etc. is not
greater than one N-th the magnification of the standard mode. In
reproduction of an N-fold long-recording-time mode, a reproduced
signal from the head amplifier 13 is subjected in the signal
processing unit 14 to N-fold time-base-expansion and
expansion-decoding, and then supplied to the digital signal input
and output terminal 17.
[0139] FIGS. 10 and 11 are timing charts showing head-selection and
record timings in signal record in the recording and reproducing
apparatus of the second embodiment of the invention. Row A shows
the azimuth of a record track, row B shows the head which is used
in record, and row C shows the record timing of the head which is
used in record. In the time axis t, the time period required for
the rotary drum 1 to make one revolution is indicated by Ts and the
zone in which record is conducted is indicated by a rectangle.
[0140] FIG. 10 shows head-selection and record timings in the
standard mode. In the standard mode, the tape 5 runs at a speed by
which the head scan position is deviated by one track pitch 1Tp
while the rotary drum 1 makes one half revolution. In the standard
mode, the heads 2b and 2a alternately conduct record for every one
half revolution of the rotary drum 1. The head 2a leads the
position opposed to the head 2b at a central angle of 180.degree.,
by an angle .theta. in the rotation direction of the rotary drum 1,
so that the start of the scanning operation of the head 2a is
earlier by the time period corresponding to revolution of the angle
.theta. of the rotary drum 1.
[0141] In consideration of the distance in which the tape 5 runs
for the time period when the rotary drum 1 makes revolution of the
angle .theta., the head 2a is attached so as to be deviated upward
as indicated by the arrow S from the head 2b by the minute height
difference .DELTA.H1. As a result of the provision of the minute
height difference .DELTA.H1, record tracks of a track pitch Tp can
be formed. The head scan is deviated by one track pitch 1Tp during
a period when the rotary drum 1 makes one half revolution
(=180.degree.), and hence the optimum height difference Hi in the
standard mode is Tp.times..theta./180. Since the heads 2a and 2b
alternately conduct record, adjacent tracks are inverted in azimuth
from each other. Therefore, high-density record is enabled without
using a guard band. It is a matter of course that the head 2a may
be located at a position which is separated in a direction opposite
to the rotation direction of the rotary drum 1 by a central angle
.theta. from the position opposed to the head 2b at
180.degree..
[0142] FIG. 11 shows head-selection and record timings in a
long-recording-time mode (2-fold long-recording-time mode) in which
the record time is two times that of the standard mode. In the
2-fold long-recording-time mode, the tape 5 runs at a speed by
which the head scan position is deviated by one track pitch 1Tp
while the rotary drum 1 makes one revolution. In the 2-fold
long-recording-time mode, the heads 2c and 2a alternately conduct
record for every revolution of the rotary drum 1. The head 2a leads
the head 2c by a central angle .theta. in the rotation direction of
the rotary drum 1, so that the start of the scanning operation of
the head 2a is earlier by the time period corresponding to
revolution of the angle .theta. of the rotary drum 1.
[0143] In consideration of the distance in which the tape 5 runs
for the time period when the rotary drum 1 makes revolution of the
angle .theta., the head 2a is attached so as to be deviated upward
as indicated by the arrow S from the head 2c by the minute height
difference .DELTA.H2. As a result of the provision of the minute
height difference .DELTA.H2, record tracks of a track pitch Tp can
be formed. The head scan is deviated by one track pitch 1Tp during
a period when the rotary drum 1 makes one revolution
(=360.degree.), and hence the optimum height difference .DELTA.H2
in the 2-fold long-recording-time mode is Tp.times..theta./360.
Since the heads 2c and 2a alternately conduct record, adjacent
tracks are inverted in azimuth from each other. Therefore,
high-density record is enabled without using a guard band. A
digital signal which is to be recorded in the 2-fold
long-recording-time mode is obtained by compression-coding a
digital signal to a data rate which is about one half that of the
standard mode and then 1/2-time-base-compressing the compressed
signal.
[0144] In the above, the operations in the standard mode and the
2-fold long-recording-time mode have been described. In an N-fold
long-recording-time mode (where N is a natural number), generally,
the running speed of the tape 5 is set to be one N-th the standard
mode and record is conducted for every N/2 revolutions of the
rotary drum 1. In other words, when the magnification N is an odd
number, record is conducted by the heads 2b and 2a, and, when the
magnification N is an even number, the heads 2c and 2a alternately
conduct record. As a result, record tracks among which adjacent
tracks are inverted in azimuth from each other can be formed at a
width which is approximately equal to the track pitch Tp. In an
N-fold long-recording-time mode, a digital signal which has been
subjected to compression-coding to a data rate which is about one
N-th that of the standard mode and then 1/N-fold
time-base-compression is recorded.
[0145] In the above, the operation in record has been described.
Also in reproduction, record tracks can be traced by operating the
heads in a similar manner as the case of record. Therefore, the
description of the operation in reproduction is omitted. A
reproduced digital signal in an N-fold long-recording-time mode is
subjected in the signal processing unit 14 to N-fold
time-base-expansion and expansion-decoding.
[0146] Next, the operation in search will be described. FIG. 12 is
a plan view of the tape 5 showing the head scan locus in search and
the arrangement of search data. In FIG. 12, boxes 20 indicate
search data. The tape 5 is caused to run at a speed which is ten
times that of the standard mode, and the revolution number of the
rotary drum 1 is adjusted so that the relative movement of the tape
and the heads is corrected, thereby conducting 10speed search. It
is assumed that the search data 20 are disposed in tracks which are
recorded by a head of the second azimuth angle or the R-azimuth
angle (hereinafter, such a track is referred to as R-azimuth
track). Since search data are disposed in tracks of the second
azimuth angle, the search data are reproduced by using the heads 2b
and 2c of the second azimuth angle. As a result, the scan locus 18
of the head 2b and the scan locus 19 of the head 2c in 10-speed
search are obtained. In search, as shown in FIG. 12, the search
data 20 are located at specific positions of the tracks 9 and the
capstan 7 is controlled so that the positions are scanned by the
heads, thereby reproducing the search data.
[0147] In the embodiment, as shown in FIG. 9, since the first
minute height difference .DELTA.H1 is produced between the heads 2b
and 2a and the second minute height difference .DELTA.H2 between
the heads 2c and 2a, a minute height difference .DELTA.H3 is
produced between the heads 2b and 2c. The minute height difference
.DELTA.H3 is a difference between the height differences .DELTA.H1
and .DELTA.H2 (=Tp.times..theta./360). In search, therefore,
deviation corresponding to the minute height difference .DELTA.H3
is produced in scan position of the heads 2b and 2c. In the
embodiment, since the heads 2b and 2c which are used in search are
mounted on the rotary drum 1 with being opposed to each other at a
central angle of 180.degree., the deviation amount in scan position
of the heads 2b and 2c in search is always constant irrespective of
the search speed.
[0148] FIG. 13 is a graph showing relationships between search
speeds and scan positions in the first and second embodiments in
the case where the track pitch Tp is 10 .mu.m and the angle .theta.
is 100. In the first embodiment, when a signal of the data rate of
the magnification 1/N (N=1 or 2) is to be recorded or reproduced,
for example, the minute height difference between the heads 2a and
2c is set to be the necessary height difference
.DELTA.S(2)=Tp.times..theta./360. At this time, also the height
difference between the heads 2b and 2c is Tp.times..theta./360. In
the case where such height differences are produced, when the
search speed is P-fold, deviation in scan position in the search
using the heads 2b and 2c is (P-1/2).times.Tp.times..theta./180. As
shown in FIG. 13, therefore, deviation in scan position in the
first embodiment is increased in proportion to the search speed and
5.3 .mu.m at 10-fold speed. In contrast, deviation in scan position
in the second embodiment is constant irrespective of the search
speed and its value .DELTA.x is 0.28 (.mu.m). Even when error
factors such as tape speed variation are considered, deviation in
scan position of such an amount allows the search data 20 to be
surely reproduced. In the embodiment, therefore, both the heads 2b
and 2c can reproduce the search data while the rotary drum 1 makes
one revolution.
[0149] As seen from the above description, according to the second
embodiment, since the heads 2b and 2c of the second azimuth angle
are disposed at positions of the rotary drum 1 which are opposed
each other at a central angle of 180.degree., the deviation amount
in scan position of the heads 2b and 2c in search can be reduced
and made always constant irrespective of the search speed. Even in
a high speed search, therefore, the search data 20 can be surely
reproduced.
[0150] Since the first minute height difference H1 is set to be
Tp.times..theta./180 and the second minute height difference H2 to
be Tp.times..theta./360, deviation in scan position in the standard
mode and the 2-fold long-recording-time mode can be eliminated.
This allows also the track pitch Tp in record and reproduction in
the standard mode and the 2-fold long-recording-time mode, to have
a predetermined normal value.
[0151] In the embodiment, in an N-fold long-recording-time mode
wherein the magnification N is an even number, the running speed of
the tape 5 is set to be one N-th the standard mode and the heads 2c
and 2a alternately conduct record or reproduction for every N/2
revolutions of the rotary drum 1. In the case where the recording
and reproducing apparatus has only modes in which the magnification
N is an even number, the heads 2c and 2a may simultaneously conduct
record or reproduction for every N revolutions of the rotary drum
1. In this case, the heads 2c and 2a are attached with a height
difference approximately equal to the track pitch Tp in the
rotation shaft direction of the rotary drum 1, and the heads 2b and
2c are attached at the same height in the rotation shaft direction
of the rotary drum 1. According to this configuration, deviation in
scan position in search is prevented from occurring.
[0152] In the embodiment, in order to eliminate deviation in scan
position in the standard mode and the 2-fold long-recording-time
mode, the first minute height difference .DELTA.H1 is set to be
Tp.times..theta./180 and the second minute height difference
.DELTA.H2 to be Tp.times..theta./360. The first and second minute
height differences .DELTA.H1 and .DELTA.H2 may be appropriately set
so that deviation in scan position does not occur in an arbitrary
mode. When the first minute height difference .DELTA.H1 is set so
that deviation in scan position does not occur in the 3-fold
long-recording-time mode, for example, the head scan position is
deviated by one track pitch 1Tp while the rotary drum 1 makes
3/2-revolutions (=540.degree.), and hence .DELTA.H1 is
Tp.times..theta./540. Alternatively, the first and second minute
height differences .DELTA.H1 and .DELTA.H2 may be set so that
deviation in scan position is minimum in a plurality of modes. In
order that deviation in scan position is minimum in two modes, the
standard mode and the 3-fold long-recording-time mode, for example,
the minute height difference .DELTA.H1 may be set to be an
intermediate value of those in the two modes, i.e.,
Tp.times..theta./270.
[0153] In the embodiment, a digital signal supplied to the digital
signal input and output terminal 17 is subjected in the signal
processing unit 14 to compression-coding to the magnification 1/N
and time-base-compression. Alternatively, as described in the first
embodiment, a digital signal of the data rate which is one N-th
record data may be supplied to the digital signal input and output
terminal 17. In the alternative, the signal processing unit 14 is
not required to conduct 1/Ncompression-coding. This is applicable
also to the output operation.
[0154] Third Embodiment
[0155] Hereinafter, a third embodiment of the present invention
will be described with reference to FIG. 14--FIG. 18.
[0156] The configuration of the recording and reproducing apparatus
of the third embodiment of the invention are similar to those of
the second embodiment, and hence its description is omitted. The
third embodiment is different from the second embodiment in the
positions of the heads and deviation in scan position. These
differences will be described.
[0157] FIG. 14 is a diagram illustrating the positions of the heads
in the recording and reproducing apparatus of the third embodiment
of the invention. Referring to FIG. 14, the heads 2b and 2c are
mounted on the rotary drum 1 at a central angle of 180.degree., and
the heads 2c and 2a are mounted in close proximity to each other in
the circumferential direction of the rotary drum 1 with a central
angle difference .theta.. The heads 2b and 2c are at the same
height in the rotation shaft direction of the rotary drum 1
indicated by the arrow S, and the heads 2c and 2a are attached with
a minute height difference .DELTA.H in the rotation shaft direction
S of the rotary drum 1. Consequently, also the minute height
difference between the heads 2b and 2c in the rotation shaft
direction of the rotary drum 1 is .DELTA.H.
[0158] The method of setting the minute height difference .DELTA.H
will be described. According to the third embodiment, deviation in
head scan can be eliminated in a specific mode by setting the
minute height difference .DELTA.H to be an appropriate value. The
method of setting the minute height difference .DELTA.H is the same
as that in the second embodiment. The minute height difference
.DELTA.H is set to be equal to a value which is obtained by
converting the distance in which the tape 5 runs for the time
period when the rotary drum 1 makes revolution of the angle
.theta., into the track pitch direction. In the standard mode, for
example, the head scan is deviated by one track pitch 1Tp during a
period when the rotary drum 1 makes one half revolution
(=180.degree.). When the minute height difference .DELTA.H is set
to be Tp.times..theta./180, therefore, deviation in scan position
between the heads 2b and 2a in the standard mode can be eliminated.
Similarly, when the minute height difference .DELTA.H is set to be
Tp.times..theta./360, deviation in scan position between the heads
2c and 2a in the 2-fold long-recording-time mode can be eliminated.
n an N-fold long-recording-time mode, therefore, when the minute
height difference .DELTA.H is set to be Tp.times..theta.
/(180.times.N), deviation in scan position between the heads can be
eliminated.
[0159] Generally, the more the running speed of the tape 5 is
lowered, the more the error in running speed of the tape 5 becomes
large. Consequently, the accuracy of record and reproduction in a
long-recording-time mode in which the tape speed is lower than that
of the standard mode is impaired. This produces a problem in that,
when deviation in scan position of the heads once occurs in a
long-recording-time mode, the accuracy of the record and
reproduction is further impaired. When the minute height difference
.DELTA.H is set so that deviation in scan position is eliminated in
a long-recording-time mode in which the tape 5 runs at a low speed,
the accuracy of record and reproduction can be prevented from being
impaired.
[0160] Next, deviation in scan position in search will be
described. In the third embodiment, the heads 2b and 2c are mounted
on the rotary drum 1 so as to be opposed to each other at a central
angle of 180.degree. and at the same height in the rotation shaft
direction of the rotary drum 1. Therefore, deviation in scan
position between the heads 2b and 2c is not produced in search,
with the result that the search accuracy is further improved as
compared with the second embodiment.
[0161] As described above, in the third embodiment, the heads 2b
and 2c of the first azimuth angle are mounted on the rotary drum 1
so as to be opposed to each other at a central angle of 180.degree.
and at the same height in the rotation shaft direction of the
rotary drum 1. Therefore, deviation in scan position between the
heads in search can be eliminated so that the search accuracy is
further improved.
[0162] Fourth Embodiment
[0163] FIG. 15 is a block diagram of the recording and reproducing
apparatus of a fourth embodiment of the invention. In the figure,
the heads 2 include the heads 2a, 2b, 2c, and 2d. A coder for
normal speed reproduction 51, a coder for search 52, a formatter
53, a coder for error correction 54, a modulator 55, a demodulator
58, a decoder for error correction 59, a deformatter 60, a decoder
for normal speed reproduction 61, a decoder for search 62, and a
switch 63 correspond to the signal processing unit 14 of the first
to third embodiments.
[0164] FIG. 17C shows the head arrangement in the embodiment.
Referring to FIG. 17C, the heads 2b and 2c have the R-azimuth
angle. The heads 2b and 2c are located at a central angle of about
180.degree., and the height difference between the heads 2b and 2c
is approximately zero. The provision of the head 2a is optional.
When the apparatus is configured as an apparatus dedicated for
reproduction, for example, the head 2a may not be provided.
[0165] The operation of the thus configured recording and
reproducing apparatus in an example case where the reference speed
for search speed reproduction N.sub.1 for a search data area is
5-fold speed will be described with reference to FIG. 16. The
reference speed for search speed reproduction N.sub.1 is a speed
which is an odd-number multiple of the standard speed. Search data
recorded at the standard speed can be detected when they are
reproduced at the reference speed for search speed reproduction
N.sub.1. First, normal data areas 100 - - - 129 . . . and 300, 302,
304, - - - 328 . . . are set. Similarly, search data areas 200,
202, 204 - - - 228 . . . are set (STEP 1 of the flowchart of FIG.
30).
[0166] In record, a digital video signal which is obtained by
A/D-converting a video signal is supplied to the coder for normal
speed reproduction 51 and the coder for search 52. The coder for
normal speed reproduction 51 outputs data for normal speed
reproduction to the formatter 53, with compressing video data as
required. In some cases, the coder 51 outputs data for normal speed
reproduction as they are or without compressing the data, to the
formatter 53. The coder for search 52 conducts on the digital video
signal data compression of a higher level than that conducted by
the coder for normal speed reproduction 51, with the result that an
image can be recorded or reproduced with a reduced data amount. The
data are then supplied as search data to the formatter 53. Since
the reference speed for search speed reproduction N.sub.1 is 5-fold
speed, tracks having the same azimuth angle are divided into track
sets V each consisting of 5 tracks (STEP 2 of the flowchart of FIG.
30). The coder for search 52 outputs the same data to the head 2c
during a period when the head 2c records the search data area of a
track set V consisting of N.sub.1 (=5) tracks having the same
azimuth angle. ).
[0167] In order to reduce the length of each search data area,
video data of one frame are divided into M divisions (where M is an
integer). For example, the case where the screen division number M
is set to be 2 so that the screen is divided into two areas, upper
and lower halves, will be described.
[0168] The coder for search 52 extracts video data T of one frame
at time t from the input video signal, and compresses the data
portion of the video data T which corresponds to the upper half of
the screen, thereby producing data Ta. During a period when the
head 2c scans one track set V, the coder supplies the data Ta to
the head 2c. Next, the coder for search 52 compresses the data
portion of the video data T which corresponds to the lower half of
the screen, thereby producing data Tb. During a period when the
head 2c scans the next track set V, the coder supplies the data Tb
to the head 2c. After the head 2c scans the two track sets V, the
coder for search 52 extracts video data (T+1) of the latest one
frame from the input video signal, and compresses the data portion
of the video data (T+1) which corresponds to the upper half of the
screen, thereby producing data (T+1)a. During a period when the
head 2c scans the next track set V, the coder supplies the data
(T+1)a to the head 2c. Similarly, the operations are sequentially
repeated. In this case, the data amount of the upper half of the
screen may be different from that of the lower half of the screen.
Furthermore, the data amount of the upper half (or the lower half)
of one screen may be different from that of the upper half (or the
lower half) of the other screen. In other words, the length of the
search data area in the track direction can be arbitrarily selected
in accordance with the data amount. The screen division number M
also can be arbitrarily set. In the above description, the head 2c
records the search data areas. Alternatively, the head 2b may
record the search data areas.
[0169] The formatter 53 rearranges data for normal speed
reproduction and search data and supplies them to the coder for
error correction 54. In a track set consisting of N.sub.1 (=5)
tracks which are recorded at the same azimuth angle and in which
the same data are recorded, the search data areas is disposed at a
position which is separated from the edge of the tape 5 by a
predetermined distance on each track. One track is divided into
plural areas. A record signal is recorded in the areas with being
divided into SYNC blocks. The SYNC blocks are respectively provided
with SYNC block numbers which are uniquely formed in one track. In
one track, the search data area is allocated with one or more SYNC
blocks. In one track set, the same search data are recorded in SYNC
blocks having the same SYNC block number. Therefore, each search
data area is formed in an area which is separated from the edge of
the tape 5 by a predetermined distance (STEP 3 of the flowchart of
FIG. 30). In the above, each track set constituting the search data
areas consists of N.sub.1 tracks. Alternatively, each track set may
consist of N.sub.1 or more tracks. The search data area may be
arbitrarily disposed with using a track set consisting of N.sub.1
or more tracks as one unit. For example, an interval may be formed
between one track set and the subsequent track set. When an audio
signal area is defined, the search data area may be disposed so as
not to overlap with the audio signal area.
[0170] In the coder for error correction 54, synchronization
information, ID information (SYNC block number, etc.), a header
(information indicative of search data, that for identifying the
track set, etc.), an error correcting code, and the like are added
to the output signal of the formatter 53. The output signal is
modulated in the modulator 55, and then applied to the heads 2
through the head amplifier 13 so as to be recorded onto the tape
5.
[0171] FIG. 16 is a plan view of the tape 5 showing the track
pattern in the embodiment. In the output signal of the formatter
53, data for normal speed reproduction are recorded in normal data
areas indicated as areas 100 . . . 129 and 300, 302, 304, . . . ,
328. The search data for the reference speed for search speed
reproduction N.sub.1 are recorded in search data areas indicated as
areas 200, 202, 204, . . . , 228.
[0172] In the normal data areas, video data of one frame are
recorded in 10 tracks. Specifically, video data for one frame at
time t are recorded in the normal data areas 100 to 109 and 300 to
308. Next, video data of one frame at time (t+1) are recorded in
the normal data areas 110 to 119 and 310 to 318.
[0173] On the other hand, the same scan data are recorded in all
the search data areas of the track set V consisting of N.sub.1 (=5)
tracks which are alternately selected (STEP 4 of the flowchart of
FIG. 30).
[0174] In the search data areas, the data Ta which are obtained by
highly compressing the data portion of the video data T of one
frame at time t which corresponds to the upper half of the screen
are recorded in 5 tracks in the search data areas 200, 202, 204,
206, and 208, and the data Tb which are obtained by highly
compressing the data portion of the video data T which corresponds
to the lower half of the screen are then recorded in 5 tracks in
the search data areas 210, 212, 214, 216, and 218. Thereafter, the
data (T+1)a which are obtained by highly compressing the data
portion of the video data (T+1) of one frame at time (t+1) which
corresponds to the upper half of the screen are recorded in 5
tracks in the search data areas 220 to 228. The operations are
sequentially repeated. When the screen division number is M, an
image of one frame is recorded in tracks the number of which is
M.times.N.sub.1.times.10 and which have the same azimuth angle, in
the search data areas. In the tracks, as a result, the update
period S of the image recorded in the search data areas is
S=2.times.M.times.N.sub.1(=20 tracks).
[0175] Next, reproduction will be described with reference to FIG.
15. Record data on the tape 5 are reproduced by the heads 2 and
then amplified by the head amplifier 13. The record data are
demodulated by the demodulator 58 and then subjected in the decoder
for error correction 59 to error correction, extraction of a
header, judgment of a SYNC block number, etc. Thereafter, the
record data are divided into data for normal speed reproduction and
search data in the deformatter 60. In normal speed reproduction,
the search data and information added in recording operation are
removed from the reproduced signal, and the reproduced signal is
then supplied to the decoder for normal speed reproduction 61. In
search speed reproduction, one SYNC block of one track set V having
the same search data is sometimes subjected to a plurality of
reproduction processes. In such a case, it is judged from the
information written in the header whether the signal in the SYNC
block indicates the search data or not. From the signal for
identifying the SYNC block number and track set of the reproduced
signal, it is then judged whether the same search data have been
subjected to a plurality of reproduction processes or not. In the
case where the same search data have been subjected to two or more
reproduction processes, when the rate of errors of the search data
reproduced in the second and subsequent reproduction processes are
lower than a reference error rate, the search data of the previous
process are replaced with those of the present process. The search
data which are determined in this way are sent to the decoder for
search 62.
[0176] As information for judging the search data, the SYNC block
number or the like may be used. As the signal for identifying the
track set, a signal may be used which is obtained by previously
recording information relating to the numbering of the track set or
a signal the level of which is inverted for every track set, into
the header, the AUX area, or the like, and then reproducing the
information. The judgment on whether the search data are to be
replaced or not may be based on a comparison between errors of the
search data in the previous process and those in the present
process. Alternatively, the operation may be modified so that, when
the SYNC block number is correctly reproduced, the replacement of
the search data is conducted.
[0177] The data for normal speed reproduction and the search data
are demodulated by the decoder for normal speed reproduction 61 and
the decoder for search 62, respectively. In normal speed
reproduction, the switch 63 selects an output of the decoder for
normal speed reproduction 61, and, in search speed reproduction at
the reference speed for search speed reproduction, selects an
output of the decoder for search 62.
[0178] Next, the method of reproducing the search data areas will
be described.
[0179] It is assumed that the gap length of each head 2 (the head
width Tw) is equal to the track pitch Tp. FIG. 17A is a plan view
of the tape 5 showing the track pattern, FIG. 17B is an enlarged
view of the search data areas, and FIG. 17C is a plan view of the
rotary drum showing the head arrangement. The scanning loci of the
heads 2c and 2b in N1-fold speed (=5-fold speed) reproduction are
indicated by 500 and 201, respectively. In 5-fold speed
reproduction, with respect to N.sub.1 (=5) tracks having the
R-azimuth angle, each of the heads 2c and 2b having the R-azimuth
angle is surely caused to scan one time the search data areas as
shown in FIG. 17A, by controlling the speed of the tape 5 by the
capstan motor 7 shown in FIG. 1 (STEP 5 of the flowchart of FIG.
30). As shown in the enlarged view of FIG. 17B, data A which are
obtained by compressing the video data T at time t which
corresponds to the upper or lower half of the screen are recorded
with being divided into a plurality of data groups, into the tracks
of the R-azimuth angle in the search data areas. In the embodiment,
for example, the data A are divided into 5 data groups A1, A2, A3,
A4, and A5 and then recorded.
[0180] In FIG. 17A, when the head 2c scans along the scanning locus
500, the data group A1 is reproduced, and, when the head 2b scans
along the scanning locus 501, the data groups A2, A3, A4, and A5
are reproduced. Consequently, all the effective data which are
recorded in the search data areas of the tracks having the
R-azimuth angle which is the same as the azimuth angle of the head
2c can be complementarily reproduced by the scans of the heads 2c
and 2b. As a result of sequentially repeating such scans, even when
the positional relationships between the heads and the record
tracks are not controlled by the capstan motor 7, all the effective
data which are recorded in the search data areas of tracks having
the R-azimuth angle can be complementarily reproduced by two scans
in total conducted by the head 2c or 2b. Since the search data
areas of a track set consisting of N.sub.1 tracks having the same
azimuth angle are collectively located at the same position on the
tracks, reproduction is hardly affected by track bending.
[0181] The case where the gap length of each head 2 (the head width
Tw) is greater than the track pitch Tp will be described with
reference to FIGS. 18A and 18B. The following description is
irrespective of the arrangement and number of the heads. FIG. 18A
is a diagram of the track pattern in the case where the head width
Tw is greater than the track pitch Tp, and FIG. 18B is an enlarged
view of the search data areas in this case.
[0182] It is assumed that, when the head 2c scans a area which is
larger than a half of the record track width, data recorded on the
tape 5 can be reproduced at an error rate which is not higher then
a predetermined one. In the case where the head width Tw is equal
to the track pitch Tp, as shown in FIGS. 17A and 17B, the data
group A1, can be reproduced from the scanning locus 500 of the head
2c and the data groups A2, A3, A4, and A5 can be reproduced from
the scanning locus 501 of the head 2b.
[0183] In the case where the head width Tw is greater than the
track pitch Tp, as shown in FIGS. 18A and 18B, the data groups A1
and A2 can be reproduced from the scanning locus 500 of the head 2c
and the data groups A1, A2, A3, A4, and A5 can be reproduced from
the scanning locus 501 of the head 2b. As a result, the data groups
A1 and A2 are reproduced two times. Consequently, the redundancy of
reproduced data is increased so that, in the case where the
reproduction outputs of the heads 2c and 2b are relatively low in
level, the reliability of data is improved. Furthermore, influence
due to deviation in scanning locus of the heads which may be caused
by the speed variation of the tape 5, the irregular rotation of the
rotary drum, or the like can be compensated.
[0184] In the above, the embodiment having a head configuration in
which the heads having the same azimuth angle are located at a
central angle of 180.degree. has been described. In the case where
the positional relationship between a record track and a head is
deviated by the track pitch Tp with respect to one head and the
other head, also a head configuration other than the
above-mentioned one can attain the same effects.
[0185] In the embodiment described above, search speed reproduction
is conducted in the forward direction. Also search speed
reproduction in the rearward direction along which the tape 5 runs
reversely can be realized in a similar manner.
[0186] In the embodiment, the search data areas are disposed only
in the tracks of the R-azimuth angle. Similarly, a plurality of
heads of the L-azimuth angle may be provided and search data areas
may be disposed in tracks which are recorded by heads of the
L-azimuth angle (hereinafter, such a track is referred to as
"L-azimuth track").
[0187] In the embodiment, one search data area is collectively
disposed at one position. Alternatively, one search data area may
be disposed with being distributed at a plurality of positions in
one track.
[0188] A search data area may be divided in an arbitrary manner in
one track, and the divided search data areas may be different in
size from each other.
[0189] In the embodiment, the search data areas are disposed so as
to correspond to at one reference speed for search speed
reproduction. Alternatively, a plurality of search data areas can
be disposed so as to correspond to a plurality of reference speeds
for search speed reproduction. In the alternative, in each of the
search data areas, the reference speed for search speed
reproduction, the number of tracks constituting a track set, the
number of screen division, and the size of the search data areas
may be arbitrarily set.
[0190] The search data areas are disposed in N.sub.1 tracks which
are alternately selected. In the case where redundancy is
insignificant, the search data areas may be disposed in N.sub.1 or
more tracks which are alternately selected.
[0191] As described above, in the second embodiment, a normal data
area which is used in normal speed reproduction, and a plurality of
search data areas which are used in search speed reproduction are
disposed in one track. The reference speed for search speed
reproduction is set to be N.sub.1 (where N.sub.1 is an odd number),
and the same data are recorded in the search data areas of a track
set consisting of N.sub.1 or more tracks having the same azimuth
angle. As a result, each of the heads 2a and 2c scans one time the
track set. Therefore, it is not required to select a track to be
scanned and to control the phase of the capstan motor 7, so that
the mode is smoothly shifted from normal speed reproduction to
search speed reproduction. Furthermore, all the effective data of
the search data areas can be complementarily reproduced by two
scans in total or reproduced by either of two scans, with the
result that search speed reproduction of a high image quality can
be realized by using search data of a simple arrangement.
[0192] When the reference speed for search speed reproduction is
set to be N.sub.1-fold speed (where N.sub.1 is an odd number), all
search data recorded in the search data areas can be reproduced in
N.sub.x-fold speed reproduction which is between -N.sub.1-fold or
more speed and N1-fold and below speed (where N.sub.x is an odd
integer which is not smaller than -N.sub.1 and not larger than
+N.sub.1). Although image is slowly updated, it is possible to
display an image. Even at a reproduction speed other the
above-mentioned speeds or in a transient state during a shift of
the reproduction speed, furthermore, a part of search data can be
reproduced so that an image is displayed.
[0193] In the above, video data which are obtained by dividing the
screen of one frame into two areas, upper and lower halves are
recorded in the search data areas. Alternatively, video data may be
intraframe-compressed so as to be separated into DC and AC
components. The screen may be divided in forizontal direction, the
screen may be divided into blocks of an arbitrary size, the number
of screen division may be increased, and the screen may not be
divided.
[0194] As video data to be recorded in the search data areas, it is
preferable to use those of the frame which is latest at the timing
when data forming each search data is recorded. Previous video data
may be arbitrarily selected. In the case where, in generation of
data for normal speed reproduction, the technique of interframe
compression in which data in a plurality of frames are compressed
is used together with intraframe compression in which data in one
frame is compressed, for example, search data may be generated from
video data which precede the timing when data forming each search
data are recorded and are intraframe compressed, and the search
data may be recorded in the search data area.
[0195] In the third embodiment, the reference speed for search
speed reproduction is set to be N.sub.1 (where N.sub.1 is an odd
number), and the same data are recorded in the search data areas of
a track set consisting of N.sub.1 or more tracks having the same
azimuth angle. In the case where a plurality of heads having at
least one of the L- and R-azimuth angles are disposed and heads of
different azimuth angles record one track for two revolutions of
the rotary drum, it is preferable that the reference speed for
search speed reproduction is set to be 2.times.N.sub.L (where
N.sub.L is an odd number) and a track set consists of N.sub.1
tracks having the same azimuth angle.
[0196] Similarly, in the case where two heads having the R-azimuth
angle and two heads having the L-azimuth angle are mounted on the
rotary drum 1 and two record tracks of the same azimuth angle are
recorded for one revolution of the rotary drum, it is preferable
that the reference speed for search speed reproduction is set to be
N.sub.H/2-fold speed (where N.sub.H is an odd number) and a track
set consists of N.sub.H tracks having the same azimuth angle. In
other words, at a certain speed for search speed reproduction, the
same data are recorded in the search data areas of tracks of the
same azimuth angle which are recorded by the heads for one
revolution of the rotary drum 1. At this time, with respect to at
least two heads of plural heads having the same azimuth angle, the
positional relationships between the heads and the record tracks
must be deviated from each other by about one track pitch Tp.
[0197] Fifth Embodiment
[0198] FIG. 19A is a plan view of the tape 5 showing an example in
which the search data areas in the fifth embodiment are disposed in
tracks of R- and L-azimuth angles, and FIG. 19B is a plan view of
the rotary drum showing the head arrangement in this example. The
heads 2c and 2b have the R-azimuth angle and the heads 2a and 2d
the L-azimuth angle. The heads having the same azimuth angle are
disposed at a central angle of 180.degree.. The height differences
among the heads 2a, 2b, 2c, and 2d are substantially zero.
[0199] Referring to FIG. 19A, the reference speed for search speed
reproduction is N.sub.1-fold speed (=5-fold speed). In the search
data areas, the data Ta which are obtained by highly compressing
the data portion of the video data T of one frame at time t which
corresponds to the upper half of the screen are recorded in the
search data areas 200, 202, 204, 206, and 208 of the track set V
consisting of 5 tracks having the R-azimuth angle. The data Tb
which are obtained by highly compressing the data portion of the
video data T which corresponds to the lower half of the screen are
recorded in the search data areas 201, 203, 205, 207, and 209 of
the track set V consisting of 5 tracks having the L-azimuth angle.
The operations are sequentially repeated.
[0200] Also in this data arrangement, in the same manner as
described in conjunction with FIG. 16, all the effective data of
the search data areas 200 to 208 of the tracks of the R-azimuth
angle can be always complementarily reproduced by one scan of both
the heads 2c and 2b or reproduced by either of two scans in total
of the heads 2c and 2b. Similarly, all the effective data of the
search data areas 201 to 209 of the tracks of the L-azimuth angle
can be always complementarily reproduced by one scan of both the
heads 2a and 2d or reproduced by either of two scans in total of
the heads 2a and 2d. When the number of screen division is M, an
image of one frame is recorded in M.times.N.sub.1(=10) tracks, in
the search data areas. The update period S of an image which is
recorded in the search data areas in tracks is S=M.times.N.sub.1
(=10 tracks), and images of 10 tracks are simultaneously updated.
As a result, in N.sub.1-fold speed search reproduction, the update
period of image can be shortened.
[0201] As described above, search data areas may be formed in
tracks of R- and L-azimuth angles. In this case, the image update
period in search speed reproduction can be shortened. Furthermore,
the data rate of data for normal speed reproduction can be
increased so that an improved image quality is obtained.
[0202] In the embodiment, the same reference speed for search speed
reproduction is set in both the search data areas of the R-azimuth
angle and those of the L-azimuth angle. Alternatively, different
reference speeds for search speed reproduction may be set in search
data areas so that the range of the speed for search speed
reproduction is widened.
[0203] In the search data areas of the R- and L-azimuth angles in
2.times.N.sub.1 or more tracks, data of both the search data areas
are simultaneously updated for each track set V. In each search
data area, the data update position can be arbitrarily determined.
The data update position in the search data area of the R-azimuth
angle may be different from that in the search data area of the
L-azimuth angle.
[0204] FIG. 20A is a plan view of the tape 5 showing another
example in which the search data areas in the fourth. embodiment
are disposed in tracks of R- and L-azimuth angles. FIG. 20B is a
plan view of the rotary drum showing the head arrangement in this
example. The heads 2c and 2b have the R-azimuth angle and the heads
2a and 2d the L-azimuth angle. The heads having the same azimuth
angle are disposed at a central angle of 1800 . The heads 2c and 2a
and the heads 2b and 2d are adjusted in height so that the head 2c
and 2a scan the same locus and the head 2b and 2d scan the same
locus of the tape.
[0205] Referring to FIG. 20A, the reference speed for search speed
reproduction is N.sub.2-fold speed (=5-fold speed) (where N.sub.2
is an integer). In the search data areas, the data Ta which are
obtained by highly compressing the data portion of the video data T
of one frame at time t which corresponds to the upper half of the
screen are recorded in the search data areas of the track set V
consisting of continuous N.sub.2 (=5) tracks. The data Tb which are
obtained by highly compressing the data portion of the video data T
which corresponds to the lower half of the screen are recorded in
the search data areas of the next track set V. The operations are
sequentially repeated.
[0206] Also in this data arrangement, in the same manner as
described in conjunction with FIG. 16, either of the sets of the
heads 2c and 2a and the heads 2b and 2d surely scans one time a
track set consisting of N.sub.2 (=5) tracks in N.sub.2-fold speed
(=5-fold speed) reproduction. In the case where the set of the
heads 2c and 2a conducts the scan, for example, all the effective
data of the search data areas of 5 tracks can be always
complementarily reproduced by one scan of both the heads 2c and 2b.
Moreover, all the effective data of the search data areas can be
reproduced by a scan of either of the heads 2c and 2b. Also in the
case where the set of the heads 2b and 2d conducts the scan, the
above is also applicable.
[0207] When the number of screen division is M, an image of one
frame is recorded in the search data areas of continuous tracks of
the number of M.times.N.sub.2 (=10). The update period S in tracks
of an image which is recorded in the search data areas is M.times.N
.sub.2 (=10 tracks). As a result, the image update period can be
shortened.
[0208] As described above, a normal data area which is used in
normal speed reproduction, and a plurality of search data areas
which are used in search speed reproduction are disposed in one
track. The reference speed for search speed reproduction is set to
be N.sub.2-fold (where N.sub.2 is an integer), and the same data
are recorded in the search data areas of a track set consisting of
continuous N.sub.2 or more tracks. As a result, either of the sets
of the heads 2c and 2a and the heads 2b and 2d surely scans one
time the track set. Therefore, all the effective data of the search
data areas can be complementarily reproduced by scans of the two
heads without controlling the phase representing renolertion
control of the capstan motor 7. All the effective data of the
search data areas are produced by the scan of either of the two
heads. The search speed reproduction of a high image quality in
which the image update period is short can be realized.
[0209] Sixth Embodiment
[0210] Hereinafter, a sixth embodiment of the invention will be
described with reference to FIGS. 21 and 22. The recording and
reproducing apparatus and normal data areas in the sixth embodiment
are the same as those of the fourth embodiment, and hence their
description is omitted.
[0211] In the sixth embodiment, the reference speed for search
speed reproduction is 3.5-fold speed (N.sub.3+0.5, where
N.sub.3=3).
[0212] FIG. 21 shows the track pattern in the fifth embodiment of
the invention. Data for normal speed reproduction are recorded by
the formatter 53 shown in FIG. 15 in normal data areas of tracks
400 to 429. Search data for the reference speed for search speed
reproduction (N.sub.3+0.5)-fold speed (3.5-fold speed) are recorded
in first and second search data areas of the tracks 400, 402, . .
., 428. The same data are recorded in the first and second search
data areas of a track set V consisting of (2.times.N.sub.3+1) (=7)
tracks having the same azimuth angle.
[0213] The distance between the centers of the first and second
search data areas in the longitudinal direction of a track is set
to be in the vicinity of an even-number multiple of the length of a
portion of a record track which the heads cross in the longitudinal
direction in (N.sub.3+0.5)-fold speed reproduction. The search data
areas are smaller in size than a area of a track from which data of
the record track can be reproduced by the heads in
(N.sub.3+0.5)-fold speed reproduction.
[0214] Data Ta which are obtained by highly compressing the data
portion of the video data T of one frame at time t which
corresponds to the upper half of the screen are recorded in the
first search data areas of the tracks 400, 402, . . . , 412 or
(2.times.N.sub.3+1) (=7) tracks. Data Tb which are obtained by
highly compressing the data portion of the video data T which
corresponds to the lower half of the screen are recorded in the
second search data areas of the tracks 400, 402, . . . , 412 or
(2.times.N.sub.3+1) (=7) tracks. Next, data (T+1)a which are
obtained by highly compressing the data portion of the video data
(T+1) of one frame at time (t+1) which corresponds to the upper
half of the screen are recorded in the first search data areas of
the 7 tracks 414 to 426. The operations are sequentially repeated.
When number of the screen division is M, therefore, an image of one
frame is recorded in tracks the number of which is
M/2.times.(2.times.N.sub.3+1)(=7) and which have the same azimuth
angle, in the search data areas. In the tracks, the update period S
of the image recorded in the search data areas is
2.times.M.times.(2N.sub.3+1)(=14 tracks).
[0215] Next, the method of reproducing the search data areas will
be described.
[0216] It is assumed that the gap length of each head (the head
width Tw) is equal to the track pitch Tp. FIG. 22A is a plan view
of the tape showing the track pattern, and FIG. 22B is a plan view
of the rotary drum showing the head arrangement. The scanning locus
of the head 2c in (N.sub.3+0.5)-fold speed (3.5-fold speed)
reproduction is indicated by 510 and 511. As seen from FIG. 22A,
with respect to the track set V consisting of
(2.times.N.sub.3+1)(=7) tracks having the same azimuth angle, the
head of the R-azimuth angle surely scans two times the first and
second search data areas in the 3.5-fold speed reproduction. In the
two scans of the head 2c, the rotation of the capstan motor 7 is
controlled and the positional relationships between the head 2c and
the record tracks are controlled so that the center of the
reproduction area (the hatched portion in FIG. 22A) of the tracks
of the R-azimuth angle from which the head 2c can reproduce record
data substantially coincides with the center of the first or second
search data area. In another method, the distance between the
center of the first search data area and that of the. reproduction
area which reproduces the area is made equal to the distance
between the center of the second search data area and that of the
reproduction area which reproduces the area.
[0217] The point for locking the positional relationships may be
obtained by means of calculation based on the tape format, or by
searching the optimum point from the reproduced signal (for
example, the SYNC block number which has been reproduced). This
position control enables the heads to always scan the approximately
central point of the search data areas. The difference between the
center of the area from which the heads can reproduce record data
in (N.sub.3+0.5)-fold speed reproduction and that of the search
data area is set as the margin of deviation in scanning locus of
the heads. The margin can be arbitrarily set depending on the size
of the search data area. In consideration of the head width and
deviation in scanning locus, namely, the search data area of the
optimum size can be set within the range from which the heads can
reproduce record data in (N.sub.3+0.5)fold speed reproduction.
According to this configuration, even when deviation in scanning
locus of the heads is caused by the speed variation of the tape 5,
the irregular rotation of the rotary drum, or the like, search
speed reproduction of a high image quality can be realized by using
the heads having the width substantially equal to the track
pitch.
[0218] When the reference speed for search speed reproduction is
(N.sub.3+0.5)-fold speed (where N.sub.3 is an integer), in
(N.sub.x+0.5)-fold s peed reproduction (where N.sub.x is an
integer) of --(N.sub.3+0.5)-fold speed or more and (N.sub.3+0.5)--
fold speed and below at which the tape runs in the direction
opposite to the running direction in normal speed reproduction, the
area from which the heads can reproduce record data is larger than
that in (N.sub.3+0.5)fold speed reproduction. Consequently, all
search data recorded in the search data areas can be reproduced.
Although image update is slow, it is possible to display an image.
Also at a reproduction speed other the above-mentioned speeds or in
a transient state during a shift of the reproduction speed,
furthermore, a part of search data can be reproduced so that an
image is displayed.
[0219] The search data areas are disposed in (2.times.N.sub.3+1)
tracks which are alternately selected. Although there arises a
disadvantage that data reproduction is redundant, the search data
areas may be disposed in (2.times.N.sub.3+1) or more tracks which
are alternately selected.
[0220] As described above, a normal data area which is used in
normal speed reproduction, and a plurality of search data areas
which are used in search speed reproduction are disposed in one
track. The reference speed for search speed reproduction is set to
be (N.sub.3+0.5)-fold speed (where N.sub.3 is an integer), and the
same data are recorded in the search data areas of a track set
consisting of (2.times.N.sub.3+1) or more tracks having the same
azimuth angle. When at (N.sub.3+0.5)-fold speed the phase is
controlled by the capstan motor 7, the heads 2c scans two times the
search data areas of the track set.
[0221] Consequently, all the effective data of the search data
areas can be reproduced by the two scans. Since it is not required
to select a track to be scanned, the mode is smoothly shifted from
normal speed reproduction to search speed reproduction. Even heads
which have the width substantially equal to the track pitch or a
small tracking margin can realize search speed reproduction of a
high image quality.
[0222] In the case where each head scans a track one time for two
revolutions of the rotary drum, the reference speed for search
speed reproduction is set to be (2.times.N'.sub.L+1)-fold speed
(where N'.sub.L is an integer), and a track set consists of
(2.times.N'.sub.L+1) tracks having the same azimuth angle. In other
words, at a certain speed for search speed reproduction, the same
data are recorded in the search data areas of tracks of the same
azimuth angle and in record tracks which are moved for two
revolutions of the rotary drum. At this time, the positional
relationships between the heads and the record tracks must be
changed from each other by about one track pitch for one revolution
of the rotary drum.
[0223] Seventh Embodiment
[0224] FIG. 23A is a plan view of the tape showing the track
pattern in a seventh embodiment of the invention. FIG. 23B is a
plan view of the rotary drum showing the head arrangement in the
embodiment. The head 2c has the R-azimuth angle and the head 2a has
the L-azimuth angle. The recording and reproducing apparatus and
normal data areas in the embodiment are the same as those of the
fourth embodiment, and hence their description is omitted.
[0225] Referring to FIG. 23A, the reference speed for search speed
reproduction N.sub.3+0.5 (where N.sub.3=5) is 5.5-fold speed. The
track 520 is a track along which the head 2c scans at
(2.times.N.sub.3)-fold speed (=10-fold speed). Search data areas
are located on the track. In the embodiment, search data areas are
disposed in three search data areas 602, 704, and 806 on the track
520. In the track set V consisting of (2.times.N.sub.3+1) tracks,
first, second, and third search data areas are formed at the same
positions as these search data areas, and the same data are
recorded in search data areas. Each search data area has a size
smaller than the region from which the heads can reproduce record
data in (2.times.N.sub.3)-fold speed reproduction.
[0226] In record, the video data T of one frame at time t are
divided into three portions. First, the data Tc which are obtained
by highly compressing the data portion which corresponds to the
upper one third of the screen are recorded in first search data
areas 600, 602, . . . , 620 of the track set V consisting of
(2.times.N.sub.3+1)(=11) tracks having the same R-azimuth angle.
The data Td which are obtained by highly compressing the data
portion which corresponds to the middle one third of the screen of
the video data T are recorded in second search data areas 700, 702,
. . . , 720 of the track set V. The data Te which are obtained by
highly compressing the data portion which corresponds to the lower
one third of the screen of the video data T are recorded in third
search data areas 800, 802, . . . , 820 of the track set V. The
record operations are sequentially repeated.
[0227] Next, reproduction will be described. At (N.sub.3+0.5)-fold
speed (=5.5-fold speed), in the track set V consisting of
(2.times.N.sub.3+1)(=11) tracks having the same azimuth angle, the
head 2c surely conducts the scan two times. In the two scans of the
head 2c, the rotation of the capstan motor 7 is controlled so that
the center of the reproduction region (the hatched portion in FIG.
23A) of the tracks of the R-azimuth angle from which the head 2c
can reproduce record data substantially coincides with the center
of each search data area, thereby controlling the positional
relationships between the head 2c and the record tracks. In another
method, the positional relationships may be controlled so that the
distance between the center of each search data area and that of
the reproduction region which reproduces the search data area is
minimum in the three search data areas. Such a control is referred
to as "phase lock," and a positional relationship which is
phase-locked is referred to as "a phase-locked point." The point
where the phase is to be locked may be obtained by means of
calculation based on the tape format, or by searching the optimum
point from the reproduced signal such as the SYNC block number
which has been reproduced.
[0228] The region from which the heads can reproduce record data at
(N.sub.3+0.5)-fold speed has a size larger than the region from
which the heads can reproduce record data at (2.times.N.sub.3)-fold
speed. Therefore, all the effective data Tc, Td, and Te of the
search data areas which are located at the three positions can be
surely reproduced. At this time, in the search data areas, an image
of one frame is recorded in (2.times.N.sub.3+1)(=11) tracks. In the
tracks, the update period S of the image recorded in the search
data areas is (2.times.N.sub.3+1)(=11) tracks.
[0229] Also in (2.times.N.sub.3)-fold speed (=10-fold speed)
reproduction, the positional relationships between the heads and
the record tracks must be controlled. However, it is not required
to select a specific track, all the effective data Tc, Td, and Te
can be reproduced, and a reproduced image of a high quality can be
obtained.
[0230] As described above, a normal data area which is used in
normal speed reproduction, and a plurality of search data areas
which are used in search speed reproduction are disposed in one
track. The reference speed for search speed reproduction is set to
be (N.sub.3+0.5) (where N.sub.3 is an integer), and the same data
are recorded in the search data areas of each track set consisting
of (2.times.N.sub.3+1) or more tracks. The search data areas are
located on the track along which the heads scan at
(2.times.N.sub.3)-fold speed, and the position is controlled by the
capstan motor 7 in 2.times.N.sub.3-fold speed and (N.sub.3+0.5)fold
speed reproduction. As a result, all the effective data can be
reproduced in (2.times.N.sub.3)-speed and (N.sub.3+0.5)fold speed
reproduction. Even when a track to be scanned is not selected,
search speed reproduction of a high image quality at a plurality of
speeds can be realized by using the heads having the width
substantially equal to the track pitch.
[0231] When the reference speed for search speed reproduction is
(N.sub.3+0.5)-fold speed (where N.sub.3 is an integer), in
(N.sub.x+0.5)-fold speed reproduction (where N.sub.x is an integer
which is not smaller than -N.sub.3 and not larger than+N.sub.3)
--(N.sub.3+0.5)-fold speed or more and (N.sub.3+0.5)--fold speed
and below, the region from which the heads can reproduce record
data is larger than that in (N.sub.3+0.5)fold speed reproduction.
Consequently, all search data recorded in the search data areas can
be reproduced. Although image update is slow, it is possible to
display an image. Also at a reproduction speed other than the
above-mentioned speeds or in a transient state during a shift of
the reproduction speed, furthermore, a part of search data can be
reproduced and an image is displayed.
[0232] In (2.times.N.sub.3)-fold speed reproduction, track bending
or the like sometimes causes deviation of scanning track of the
heads so that all the search data cannot be reproduced. In such a
case, data to be recorded in each search data area are repeatedly
recorded in the longitudinal direction of a track, whereby
tolerance for deviation of scanning track can be increased. The
data which are repeatedly recorded in the longitudinal direction of
a track may be a part of the data to be recorded in the search data
area or the whole of the data. FIG. 24 is an enlarged view of an
example of the search data area. In the figure, data are recorded
in one search data area (B) with being divided into 5 data groups
B1, B2, B3, B4, and B5. In the one search data area (B), the data
groups B5, B1, B2, B3, B4, B5, and B1 are recorded in the
longitudinal direction of a track indicated by the arrow L, or the
data groups of the data B are recorded in a partly repeated manner.
In reproduction, when there is no deviation of scanning track, the
data B can be reproduced in the sequence of B1, B2, B3, B4, and B5
as indicated by solid lines. Even when scanning track is deviated
from the original position as indicated by broken lines, all the
data groups of the data B can be reproduced in the sequence of B2,
B3, B4, B5, and B1. Consequently, the margin of deviation of
scanning track can be increased by recording data to be recorded in
the search data area, in a partly repeated manner. When the search
data area can be made large, the data groups of the same data B are
repeated plural times in the sequence of, for example, B1, B2, B3,
B4, B1, B2, B3, and B4.
[0233] FIG. 25A is a plan view of the tape showing an example in
which the search data areas in the embodiment are disposed in
tracks of R- and L-azimuth angles, and FIG. 25B is a plan view of
the rotary drum showing the head arrangement in this example. The
head 2a has the L-azimuth angle and the heads 2b has the R-azimuth
angle. The heads 2a and 2b are disposed at a central angle of 180
deg. The height difference between the heads 2a and 2b is
substantially zero.
[0234] The reference speed for search speed reproduction N.sub.4 is
4-fold speed. The reference speed for search speed reproduction
N.sub.4 indicates a reproduction speed which is an even-number
multiple. The tracks 530 and 531 are tracks along which the heads
2b and 2a scan at (2.times.N.sub.4-1)-fold speed (=7-fold speed),
respectively. The search data areas are located on the tracks. In
the embodiment, for example, the search data areas are located in
two areas 602 and 704 on the track 530. In the track set V
consisting of 2.times.N.sub.4 tracks, first and second search data
areas are formed at the same positions as these search data areas.
The same data are recorded in the search data areas in the track
set V.
[0235] The search data areas have a size smaller than a region from
which the heads can reproduce record data in
(2.times.N.sub.4-1)-fold speed reproduction.
[0236] Also in such a data arrangement, in the same manner as
described in conjunction with FIG. 24, the heads 2a and 2b surely
scan one time the search data areas of the track set V consisting
of 2.times.N.sub.4 continuous tracks. All the effective data of the
search data areas of the tracks of the R-azimuth angle can be
surely omplementarily reproduced by one scan of both the heads 2a
and 2b or reproduced by either of two scans in total of the heads
2a and 2b.
[0237] As described above, a normal data area which is used in
normal speed reproduction, and a plurality of search data areas
which are used in search speed reproduction are disposed in one
track. The reference speed for search speed reproduction is set to
be N.sub.4 (where N.sub.4 is an even number), and the same data are
recorded in the search data areas of each track set consisting of
(2.times.N.sub.4) or more continuous tracks. The search data areas
are recorded so as to be located on the track along which the heads
scan at (2.times.N.sub.4-1)-fold speed in reproduction. At
(2.times.N.sub.4-1)-fold speed and N.sub.4-fold speed, the position
is controlled by the capstan motor 7. As a result, all the
effective data of the search data areas can be reproduced in
(2.times.N.sub.4-1)-fold speed and N.sub.4-fold speed reproduction.
Even when a track to be scanned is not selected, therefore, search
speed reproduction of a high image quality at a plurality of speeds
can be realized by using the heads having the width substantially
equal to the track pitch.
[0238] Eighth Embodiment
[0239] FIG. 26A is a plan view of the tape showing the track
pattern in a eighth embodiment of the invention, and FIG. 26B is a
plan view of the rotary drum showing the head arrangement in the
embodiment. The head 2a has the L-azimuth angle and the heads 2c
and 2b have the R-azimuth angle. The recording and reproducing
apparatus and normal data areas in the eighth embodiment are the
same as those of the first embodiment, and hence their description
is omitted.
[0240] Referring to FIG. 26A, the reference speed for search speed
reproduction N.sub.1 is 5-fold speed. The track 540 is a track
along which the heads 2c and 2b scan at (2.times.N.sub.1)-fold
speed (=10-fold speed). Search data areas are located on the track.
In the embodiment, for example, search data areas are disposed in
three search data areas 602, 704, and 806 on the track 540. In the
track set V consisting of N.sub.1 tracks, first, second, and third
search data areas are formed at the same positions as the search
data areas 602, 704, and 806. The same data are recorded in the
search data areas in the track set V. The widths of the heads 2c
and 2b are approximately equal to the track pitch. Each search data
area has a size smaller than the region from which the heads 2c and
2b can reproduce record data in (2.times.N.sub.1)-fold speed
reproduction.
[0241] In record, the video data T of one frame at time t are
divided into three portions in the same manner as the fourth
embodiment. First, the data Tc which are obtained by highly
compressing the data portion which corresponds to the upper one
third of the screen are recorded in search data areas 600, 602, . .
. , 608 of the track set consisting of N.sub.1 (=5) tracks having
the R-azimuth angle. The data Td which are obtained by highly
compressing the data portion which corresponds to the middle one
third of the screen of the video data T are recorded in search data
areas 700, 702, . . . , 708. The data Te which are obtained by
highly compressing the data portion which corresponds to the lower
one third of the screen of the video data T are recorded in search
data areas 800, 802, . . . , 808. The record operations are
sequentially repeated.
[0242] Next, reproduction will be described.
[0243] In reproduction at N.sub.1-fold speed (=5-fold speed), as
shown by tracks 541 and 542, the head 2c surely scans two times the
track set V consisting of N.sub.1 (=5) tracks having the same
azimuth angle. In the two scans, a phase-locked point which scans
one time each of the three search data areas of the track set V
always exists. The region from which the heads can reproduce record
data at N.sub.1-fold speed is larger than the region from which the
heads can reproduce record data at (2.times.N.sub.1)-fold speed.
Even when heads having the width substantially equal to the track
pitch are used, therefore, all the effective data Tc, Td, and Te of
the search data areas-which are located at the three positions can
be surely reproduced. At this time, in the search data areas, an
image of one frame is recorded in N.sub.1 (=5) tracks. The update
period S in tracks and of an image which is recorded in the search
data areas is N.sub.1 (=5) tracks.
[0244] Also in (2.times.N.sub.1)-fold speed (=10-fold speed)
reproduction, the positional relationships between the heads and
the record tracks must be controlled. However, without requiring
selection of a specific track, all the search data Tc, Td, and Te
can be reproduced, and a reproduced image of a high quality can be
obtained.
[0245] As described above, a normal data area which is used in
normal speed reproduction, and a plurality of search data areas
which are used in search speed reproduction are disposed in one
track. The reference speed for search speed reproduction is set to
be N.sub.1 (where N.sub.1 is an odd number), and the same data are
recorded in the search data areas of each track set V consisting of
N.sub.1 or more tracks having the same azimuth angle. The search
data areas are recorded on the track along which the heads scan at
(2.times.N.sub.1)-fold speed in reproduction. At
(2.times.N.sub.1)fold speed and N1-fold speed, the phase is
controlled by the capstan motor 7. As a result, at reproduction
speeds of (2.times.N.sub.1)-fold speed and N.sub.1-fold speed, all
the effective data of the search data areas can be reproduced. Even
when a track to be scanned is not selected, search speed
reproduction of a high image quality at a plurality of speeds can
be realized by using the heads having the width substantially equal
to the track pitch.
[0246] When the reference speed for search speed reproduction is
set to be N.sub.1 (where N.sub.1 is an odd number), in N.sub.x-fold
speed reproduction (where N.sub.x is an odd number) of
--N.sub.1-fold speed or more and N.sub.1-fold speed and below, all
the search data recorded in the search data areas can be
reproduced. Although image update is slow, it is possible to
display an image. Also at a reproduction speed other than the
above-mentioned speeds or in a transient state during a shift to
the reproduction speed, furthermore, a part of search data can be
reproduced and an image is displayed.
[0247] In the same manner as the seventh embodiment, the margin of
deviation of scanning track particularly in (2.times.N.sub.1)-fold
speed reproduction can be increased by recording data to be
recorded in the search data area, in a partly repeated manner in
the longitudinal direction of a track.
[0248] The search data areas are configured by 2.times.N tracks
which are alternately selected. In the case where redundancy is
insignificant, the search data areas may be configured by
2.times.N.sub.1 or more tracks which are alternately selected.
[0249] Ninth Embodiment
[0250] FIG. 27 is a plan view of the tape showing the track pattern
in a ninth embodiment of the invention. The configuration of the
recording and reproducing apparatus and normal data areas of the
ninth embodiment are similar to those of the fourth embodiment. The
search data areas are located in the same manner as those of the
fifth embodiment.
[0251] As shown in FIG. 27, the same data Ta are recorded in the
search data areas of the track set V consisting of K (=13) tracks
(where K is an integer which is not less than 4) having the same
azimuth angle. The speed for search speed reproduction is K/W-fold
speed (where W is an integer which is not less than 3). When the
screen division number M is set to be 2, in the search data areas,
an image of one frame is recorded in MXK (=26) tracks having the
same azimuth angle. In the tracks, the update period S of the image
recorded in the search data areas is 2.times.M.times.K (=52)
tracks.
[0252] Next, the method of reproducing the search data areas will
be described.
[0253] It is assumed that the gap length of each head (the head
width Tw) is equal to the track pitch Tp. FIG. 28A is a diagram of
the track pattern, FIG. 28B is a plan view of the rotary drum
showing the head arrangement, and FIG. 28C is a view showing
positional relationships of the heads. The scanning track of the
head 2c in reproduction wherein the speed for search speed
reproduction K/W is 13/3-fold speed (=4.33-fold speed, where K=13
and W=3) is indicated by 551 and 552. As seen from FIG. 28A, with
respect to the K (=13) tracks having the same azimuth angle, the
head 2c scans three times the track set V in 4.33-fold speed
reproduction even when the rotation of the capstan motor 7 is not
controlled. In the three scans, the head surely scans the whole of
the search data areas.
[0254] As shown in FIG. 28C, the scanning track of the head 2c on
the record track R of R-azimuth angle is deviated by one third of
the track pitch Tp (Tp/3) for each scan. Therefore, the head 2c
duplicately scans the region of the track from which record data
can be reproduced. Specifically, when the head 2c having the width
equal to the track pitch Tp is used, three scans of the head 2c on
the track in which the same data are recorded relatively produce
duplication which corresponds to one third of the track pitch Tp in
the head width direction. This duplication width serves as the
margin of deviation of scanning track of the head from the search
data area. Even when deviation of scanning track occurs, therefore,
all the data of the search data areas can be reproduced in
reproduction wherein the speed for search speed reproduction K/W is
13/3-fold speed (=4.33-fold speed), by using the heads having the
width substantially equal to the track pitch. In other words, even
when the track bend, the speed variation of the tape, the irregular
rotation of the rotary drum, or the like occurs, search speed
reproduction of a high image quality can be realized by using the
heads having the width substantially equal to the track pitch,
without controlling the capstan motor 7.
[0255] In the same manner as the sixth embodiment, even when the
speed for search speed reproduction is K/W=(N.sub.y+0.5)-fold speed
(where N is an integer), all the data of the search data areas can
be reproduced by controlling the phases of the heads and the record
tracks, with the result that a reproduced image of a high quality
can be obtained. When heads having the width greater than the track
pitch are used, all the data for search can be reproduced by
controlling only the speed of the tape 5.
[0256] In the above, the embodiment in which reproduction is
conducted at the K/W-fold speed for search speed reproduction
wherein the integer W indicative of the speed for search speed
reproduction is 3 has been described. Similarly, the same data are
recorded at the same position of each track in the search data
areas of the track set consisting of K tracks (where K is an
integer which is not less than 4) having the same azimuth angle. As
a result, when the ratio K.sub.x/W (where K.sub.x is a positive
integer which is not larger than K and W is an integer which is not
less than 3) is not an integer, all search data recorded in the
search data areas can be reproduced also in reproduction conducted
at the K.sub.x/W-fold speed for search speed reproduction wherein
the speed for search speed reproduction is not lower than -K/W-fold
speed and not higher than K/W-fold speed. Although image update is
slow, it is possible to display an image. Also at a reproduction
speed other than the above-mentioned speeds or in a transient state
during a shift of the reproduction speed, furthermore, a part of
search data can be reproduced and an image is displayed.
[0257] As described above, a normal data area which is used in
normal speed reproduction, and a plurality of search data areas
which are used in search speed reproduction are disposed in one
track. The same data are recorded in the search data areas of a
track set consisting of K or more tracks (where K is an integer
which is not less than 4) having the same azimuth angle. The search
data areas are located in a band-like region in each track which
elongate in parallel with the tape running direction. As a result,
when the ratio K/W is not an integer, all effective data of the
search data areas can be reproduced in reproduction conducted at
K/W-fold speed. Even when the heads having the width substantially
equal to the track pitch are used, all effective data of the search
data areas can be reproduced by W or more scans (where W is an
integer which is not less than 3) without requiring the positional
relationships between the heads and the record tracks to be
controlled. As a result, search speed reproduction of a high image
quality can be realized. Since the same data are commonly used in
reproductions of different reproduction speeds, wasted search data
can be reduced and the arrangement of search data can be
simplified. Since it is not required to select a track to be
scanned and control the positional relationships between the heads
and the tracks, the mode can be smoothly shifted from normal speed
reproduction to search speed reproduction.
[0258] Also in the case where two or more heads of the same azimuth
angle are provided as in the fourth embodiment, the same data are
recorded in the search data areas of a track set consisting of K or
more tracks (where K is an integer) having the same azimuth angle.
As a result, when 2.times.K/W is not an integer, all effective data
of the search data areas can be reproduced by W scans in total of
the heads of the same azimuth angle in reproduction conducted at a
speed for search speed reproduction 2.times.K/W-fold speed.
[0259] Tenth Embodiment
[0260] FIG. 29A is a plan view of the tape showing the track
pattern in a tenth embodiment of the invention. The configuration
of the recording and reproducing apparatus, and arrangement of
normal data areas and search data areas of the tenth embodiment are
similar to those of the fourth embodiment, and hence their
description is omitted.
[0261] In record, an AUX area which has a band-like shape and
elongates in the tape running direction is formed in a part of each
search data area. In a track where no search data area exists, the
AUX area formed in a part of each search data area is extended in
the tape running direction so that the AUX areas are located at the
same positions of the tracks. In the AUX area, recorded are
information of the record format (for example, the record mode),
that of the signals recorded in the normal data areas (for example,
the packet size, the date and time of record, and the elapsed time
period), that of the signals recorded in the search data areas (for
example, the number of tracks of the search data areas in which the
same data are recorded, and the reference speed for search speed
reproduction), etc. It is a matter of course that such information
may be coded and then recorded. An analog signal may be recorded as
it is. With respect to such information, it is not required to
record the same information in all tracks of a track set consisting
of N.sub.1 (=5) tracks having the same azimuth angle. In one
software (for example, a program of broadcasting), for example, the
date and time of record are the same in all the tracks, but the
elapsed time period may be different from each other in all the
tracks.
[0262] In normal speed reproduction, since the heads trace the
record tracks, all information recorded in the AUX areas can be
reproduced.
[0263] Also in reproduction at the reference speed for search speed
reproduction which is N.sub.1-fold speed, since the AUX areas are
disposed in the search data areas, information recorded in the AUX
areas can be reproduced.
[0264] As described above, since the AUX areas are disposed in the
search data areas, data recorded in the AUX areas can be reproduced
in normal speed reproduction and search speed reproduction.
[0265] In the embodiment, the search data area is disposed at one
position in the longitudinal direction of the tape. The search data
area may be configured in an arbitrary manner. Also in the case
where a plurality of search data areas are disposed in the
longitudinal direction of the tape or the search data area is
disposed in head scanning track at a certain speed for search speed
reproduction, the same effects are attained when the AUX area is
formed in a part of the search data area. When a plurality of
search data areas are disposed for a plurality of speeds for search
speed reproduction, the AUX area may be disposed in a part of the
plurality of search data areas. When search data areas for
different speeds for search speed reproduction are to be disposed
in tracks of the R- and L-azimuth angles, for example, the AUX area
is formed in the search data areas of the R- and L-azimuth angles.
According to this configuration, information of the AUX area can be
reproduced at these speeds for search speed reproduction. When the
AUX area is formed at a position where the search data areas
overlap with each other in the longitudinal direction of a track,
the AUX area can be formed at a position which is always constant
in the longitudinal direction of a track, so that the AUX area can
be easily detected.
[0266] In the example described above, the AUX area is disposed in
all tracks. Alternatively, the AUX area may be disposed at
intervals of several tracks.
[0267] In the case where a control track CT for recording a control
signal is disposed in the longitudinal direction of the tape 5, as
shown in FIG. 29, the control signal is modulated by a
predetermined signal at the boundary of the track set V. As a
result, the boundary of the track set can be detected on the basis
of the control signal. Even when a signal for identifying the track
set V is not recorded, the track set V can be judged and hence
search speed reproduction can be easily realized. In edition such
as splicing, data can be easily protected in the unit of the track
set V. As described as the prior art example, when also the system
in which search data are disposed on the scanning track of a head
is used in the track set V, the position of the track which is to
be scanned for reproducing the search data is defined with respect
to the start track of the track set V so that the delimitation of
the track set is clarified by the modulated control signal.
Consequently, the track to be scanned can be easily selected. The
control signal may be modulated by an arbitrary method. When the
start in search is accessed on the basis of the control signal, for
example, modulation may be conducted in a method different from the
above. When a plurality of search data areas which are different
from each other in the number of tracks constituting the track V
are disposed, the control signal is modulated in different methods
and modulations of different methods may be applied to the
delimitations of the track sets V of the search data areas,
respectively.
[0268] In the above, the embodiments in which video data are
recorded in the normal data areas and the search data areas have
been described. Data such as video data, audio data, or additional
information including time codes may be recorded. Different data
are recorded in the plurality of search data areas. Alternatively,
the same data may be recorded in the plurality of search data
areas, thereby increasing the redundancy of the data so as to
reduce errors.
[0269] The number of screen division can be arbitrarily set, and
may be variable with using a track set or a search data area as a
unit. In the embodiments, an image of one frame is first divided
and then compressed. Alternatively, the image may be first
compressed and then divided, or may not be compressed.
[0270] In each search data area, the reference speed for search
speed reproduction, the image update position, the compression
method, and the compression rate can be arbitrarily determined. It
is possible to obtain optimum search speed reproduction image for a
plurality of reference speeds for search speed reproduction.
[0271] In the embodiments described above, in the normal data areas
and search data areas, tracks in which video data of one frame at a
certain time are constant in number. Alternatively, variable-length
coding may be conducted so that the number of tracks per frame and
the size of a recorded area are variable.
* * * * *