U.S. patent application number 09/851249 was filed with the patent office on 2001-10-11 for digital information recording apparatus and digital information recording and reproducing apparatus.
Invention is credited to Amada, Nobutaka, Arai, Takao, Noguchi, Takaharu.
Application Number | 20010028520 09/851249 |
Document ID | / |
Family ID | 23603051 |
Filed Date | 2001-10-11 |
United States Patent
Application |
20010028520 |
Kind Code |
A1 |
Amada, Nobutaka ; et
al. |
October 11, 2001 |
Digital information recording apparatus and digital information
recording and reproducing apparatus
Abstract
A digital information recording apparatus having a first
recording mode recording a first digital information signal of a
first information rate on a magnetic tape and a second recording
mode recording a second digital information signal of a second
information rate on the magnetic tape. The apparatus includes a
circuit which when the second information rate is less than 1/N
times the first information rate (N is an integer .gtoreq.2), adds
a dummy signal to the second digital information signal to make the
recording rate of the second digital information signal
substantially equal to the recording rate of the first digital
information signal and a circuit which multiplexes identification
signals for identifying the first and the second digital
information signals or the first and the second recording rates on
the first or the second digital information signal, for
recording.
Inventors: |
Amada, Nobutaka;
(Yokohama-shi, JP) ; Noguchi, Takaharu;
(Yokohama-shi, JP) ; Arai, Takao; (Yokohama-shi,
JP) |
Correspondence
Address: |
ANTONELLI TERRY STOUT AND KRAUS
SUITE 1800
1300 NORTH SEVENTEENTH STREET
ARLINGTON
VA
22209
|
Family ID: |
23603051 |
Appl. No.: |
09/851249 |
Filed: |
May 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09851249 |
May 9, 2001 |
|
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09405288 |
Sep 23, 1999 |
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Current U.S.
Class: |
360/39 ; 360/8;
386/343; 386/E5.047; G9B/15.017; G9B/15.03; G9B/15.058; G9B/20.001;
G9B/20.014; G9B/27.033 |
Current CPC
Class: |
B01F 23/2334 20220101;
H04N 5/9261 20130101; B01F 27/112 20220101; G11B 2020/10592
20130101; B01F 23/23363 20220101; G11B 20/00007 20130101; G11B
15/1875 20130101; H04N 5/78263 20130101; B01F 23/2333 20220101;
G11B 20/1866 20130101; G11B 20/10527 20130101; G11B 2220/90
20130101; G11B 27/3027 20130101; H04N 5/9201 20130101; B01F 23/2331
20220101; G11B 15/125 20130101; G11B 15/4673 20130101; B01F 27/80
20220101; H04N 5/93 20130101 |
Class at
Publication: |
360/39 ; 386/68;
386/7; 360/8 |
International
Class: |
G11B 005/09; G11B
020/10; H04N 005/91; H04N 009/79; G11B 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 16, 1994 |
JP |
06-045993 |
Claims
What is claimed is:
1. A digital information recording apparatus having a first
recording mode recording a first digital information signal of a
first information rate on a magnetic tape to be fed at a first feed
speed and a second recording mode recording a second digital
information signal of a second information rate of 1/n times said
first information rate (where n is a real number of not less than
2) on the magnetic tape to be fed at a second feed speed of 1/N
said first feed speed (where N is an integer of not less than 2),
comprising: a circuit which when said second information rate is
less than 1/N times said first information rate, adds a dummy
signal to said second digital information signal to make the
recording rate of said second digital information signal
substantially equal to the recording rate of said first digital
information signal; and a circuit which multiplexes identification
signals for identifying said first and said second digital
information signals or said first and said second recording rates
on said first or said second digital information signal, for
recording.
2. A digital information recording apparatus according to claim 1,
comprising: a circuit for said first recording mode which records
said first digital recording signal to four tracks on said magnetic
tape per one revolution of a rotary drum with magnetic heads
thereon; and a circuit for said second recording mode which records
said second digital information signal to four tracks on said
magnetic tape per N revolutions of said rotary drum.
3. A digital information recording apparatus comprising: encoding
means for encoding a digital information signal having a plurality
of different information rates into a predetermined recording
signal; recording means for recording said recording signal to a
helical track on a magnetic tape using a magnetic head mounted on a
rotary drum; servo means for rotating said rotary drum at a
predetermined speed and causing movement of said magnetic tape at a
predetermined feed speed or 1/N the predetermined feed speed(where
N is an integer of not less than 2) in accordance with said
information rate of said digital information signal to be recorded;
wherein said encoding means comprises: a circuit which when the
information rate of said digital information signal to be recorded
on said magnetic tape to be fed at 1/N said predetermined feed
speed is less than 1/N times an information rate of said digital
information signal to be recorded on the magnetic tape to be fed at
a predetermined speed, adds a dummy signal to said digital
information signal to be recorded on said magnetic tape to be fed
at 1/N said predetermined speed to provide a recording signal
having the predetermined recording rate; and a circuit which
multiplexes identification signals for identifying said digital
information signals having different information rates or said feed
speed of the magnetic tape on said digital information signal to be
recorded, for encoding.
4. A digital information recording apparatus according to claim 3,
wherein said recording means comprises: a circuit which records,
said digital information signal to be recorded on said magnetic
tape fed at said predetermined feed speed, to four tracks on said
magnetic tape per one revolution of a rotary drum; and a circuit
which records, said digital information signal recording on said
feed tape to be fed at 1/N said predetermined feed speed, to four
tracks on said magnetic tape per N revolutions of said rotary
drum.
5. A digital information recording and reproducing apparatus having
a first recording and reproducing mode recording and reproducing a
first digital information signal of a first information rate on a
magnetic tape to be fed at a first feed speed and a second
recording and reproducing mode recording and reproducing a second
digital information signal of a second information rate of 1/n
times said first information rate (where n is a real number of not
less than 2) on the magnetic tape to be fed at a second feed speed
of 1/N said first feed speed (where N is an integer of not less
than 2), comprising: a circuit for recording which when said second
information rate is less than 1/N times said first information
rate, adds a dummy signal to said second digital information signal
to make the recording rate of said second digital information
signal substantially equal to the recording rate of said first
digital information signal; and a circuit which multiplexes
identification signals for identifying said first and said second
digital information signals or said first and said second recording
rates, on said first or said second digital information signal; and
a circuit for reproduction which detects the multiplexed
identification signal to identify an original of said first or
second digital information signal based on the detection
result.
6. A digital information recording and reproducing apparatus
according to claim 5, comprising: a circuit for said first
recording and reproducing mode which records and reproduces said
first digital recording signal to four tracks on said magnetic tape
per one revolution of a rotary drum with magnetic heads thereon;
and a circuit for said second recording and reproducing mode which
records and reproduces said second digital information signal to
four tracks on said magnetic tape per-N-revolutions of said rotary
drum.
7. A digital information recording and reproducing apparatus
comprising: encoding means for encoding a digital information
signal having a plurality of different information rates into a
predetermined recording signal; recording and reproducing means for
recording and reproducing said recording signal to a helical track
on a magnetic tape using a magnetic head mounted on a rotary drum;
decoding means for decoding an original digital information signal
from a signal reproduced from said tape; servo means for rotating
said rotary drum at a predetermined speed and causing movement of
said magnetic tape at a predetermined feed speed or 1/N the
predetermined feed speed(where N is an integer of not less than 2)
in accordance with said information rate of said digital
information signal to be recorded; wherein said encoding means
comprises: a circuit which when the information rate of said
digital information signal to be recorded on said magnetic tape to
be fed at 1/N said predetermined feed speed is less than 1/N times
an information rate of said digital information signal to be
recorded on the magnetic tape to be fed at a predetermined speed,
adds a dummy signal to said digital information signal to be
recorded on said magnetic tape to be fed at 1/N said predetermined
speed to provide a recording signal having the predetermined
recording rate; a circuit which multiplexes identification signals
for identifying said digital information signals having different
information rates or said feed speed of the magnetic tape, on said
digital information signal to be recorded, for encoding; and
wherein said decoding means comprises: a circuit which detects the
multiplexed identification signal to identify an original of said
first or second digital information signal based on the detection
result.
8. A digital information recording apparatus according to claim 7,
wherein said recording and reproducing means comprises: a circuit
which records, said digital information signal to be recorded on
said magnetic tape to be fed at said predetermined feed speed, to
four tracks on said magnetic tape per one revolution of a
rotary-drum; and a circuit which records, said digital information
signal to be recorded on said feed tape to be fed at 1/N said
predetermined feed speed, to four tracks on said magnetic tape per
N revolutions of said rotary drum.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a digital information
signal recording apparatus and a digital information signal
recording and reproducing apparatus, and in particular, to a
digital information signal recording apparatus and a digital
information signal recording and reproducing apparatus suitable for
selecting and recording a plurality of video signals encoded into
digital compression codes of different transmission rates and
selecting and reproducing the recorded signals thereafter.
[0002] An example of a digital video tape recorder (VTR) in which a
video signal is converted into a digital compression code for the
recording and reproducing of the signal is described, for example,
in two articles respectively in pages 588 to 596 and pages 597 to
605 of "IEEE Transactions on Consumer Electronics", Vol. 34, No. 3
(August 1988).
[0003] On the other hand, a digital broadcast is being put to
practical use as a television (TV) broadcast of the next
generation. For example, in the United States of America, there is
known an advanced television (ATV) system in which a
high-definition (HD) wide-band video signal having a resolution
higher than that of a standard-definition (SD) video signal of the
National Television System Committee (NTSC) system (525 lines/60
fields) or Phase Alteration Line (PAL) system (625 lines/50 fields)
currently used is converted into a highly efficient digital
compression code, thereby broadcasting the signal in the 6
megahertz (MHz) band-width presently used for TV broadcasting
facilities. In addition, in association with the
standard-definition system, there is known a system called "Direct
TV" in which signals of a plurality of programs are converted into
highly efficient digital compression codes respectively according
to moving picture expert groups (MPEGs) such that the signals are
transmitted via a satellite using time division multiplex
communication.
[0004] In this situation, when these digital TV broad-casts are
actually introduced to practical use, there are required digital
VTRs corresponding thereto. However, in the prior art described
above, consideration has not been given to technology for selecting
and recording a plurality of digital TV signals of different
transmission rates and selectively reproducing the signals
thereafter.
[0005] An example of the apparatus in which a plurality of digital
TV signals having different transmission rates are selectively
recorded and reproduced is described in the U.S. Pat. No. 5,065,259
(corresponding to the JP-A-1-258255). This apparatus supports a
plurality of recording modes such that information signals are
encoded into digital data items of different transmission rates
according to the recording modes. The encoded digital data items
are then converted into signals of a fixed recording rate through a
time-base or time-axis process. The obtained signals are recorded
on a magnetic tape at a tape feed speed related to the transmission
rates of the encoded digital data items, respectively.
[0006] However, in the apparatus of the U.S. Pat. No. 5,065,259,
there has been missing technology associated with the automatic
decisions of the recording modes in the signal reproduction
process. Moreover, since an encoder is integrally included in the
apparatus, consideration has not been given to the recording of
such signals of digital data as digital video signals encoded in
the MPEG system in which the transmission rate thereof varies with
respect to time as well as for each of the programs, for example,
programs of movies, sports, and news.
SUMMARY OF THE INVENTION
[0007] It is therefor an object of the present invention to provide
a digital information recording apparatus and a digital information
recording and reproducing apparatus for selecting and recording a
plurality of digital video signals converted into digital
compression codes having different transmission rates and selecting
and reproducing the recorded signals, thereby solving the problem
of the prior art.
[0008] To achieve the above object, a digital information recording
and reproducing apparatus according to an aspect of the present
invention comprises selecting means for selecting a signal to be
recorded from a plurality of digital information signals having
different transmission rates, identifier signal generator means for
generating an identifier signal indicating contents of the selected
signal, encoding means for conducting an interleaving process for
the selected signal, forming blocks thereof by adding a
synchronizing code, an identification code, an error correction
code, and dummy data thereto, executing a time-base process and a
modulation for the signal, thereby converting the signal into two
channels of recording signals, recording and reproducing means
including a first magnetic head and a second magnetic head
respectively having azimuth angles respectively having opposing
polarities and a third magnetic head and a fourth magnetic head
opposing to the first and second magnetic heads with an angle of
180.degree., decoding means for conducting for a reproduction
signal such decoding processes reverse to those of the encoding
means as an equalizing process, a demodulating process, an error
correcting process, and a deinterleaving process, thereby
converting the reproduction signal into the original digital
information signal, and servo means for controlling a rotation
speed of a rotary drum and a feed speed of a magnetic tape.
[0009] When recording a first digital information signal in a range
between a preset maximum transmission rate and one half thereof,
the encoding means adds data such as dummy data thereto to convert
the signal into two channels of recording signals having a fixed
recording rate determined by the maximum transmission rate
regardless of the input transmission rate, the servo means turns
the rotary drum at a fixed rotation speed to feed the magnetic tape
at a first feed speed, and the recording and reproducing means
records and reproduces the two channels of recording signals on
four tracks in one rotation of the rotary drum by alternately using
the first and second magnetic heads and third and fourth magnetic
heads.
[0010] On the other hand, when recording the second digital
information signal in a range which is 1/N (N is an integer equal
to or more than two) of that of the first digital information
signal, the encoding means further compresses, each time the rotary
drum makes N/2 rotations, the second digital information signal
into a signal which is 1/N of the second digital information signal
on a time axis, thereby converting the signal into two channels of
recording signals respectively having the fixed recording rates,
the servo means turns the rotary drum at the fixed rotary speed to
feed the magnetic tape at a second feed speed equal to 1/N of the
first feed speed, and the recording and reproducing means records
and reproduces the two channels of recording signals on four tracks
in one rotation of the rotary drum by using only the first and
second magnetic heads or by alternately using the first and second
magnetic heads and third and fourth magnetic heads. In this
situation, the identifier signal indicating the contents of the
recorded signal is also recorded as one of the identification (ID)
codes together with the digital information signals.
[0011] The signals-reproduced by the first and second magnetic
heads and/or the third and fourth magnetic heads are subjected in
the decoding means to such processes reverse to those of the
encoding means as equalization, demodulation, error correction, and
deinterleaving so as to be converted into the original first or
second digital information signal. In this operation, the decoding
means detects the identifier signal thus recorded to control the
time-axis process of its own and outputs to the servo means a
reference signal to control the tape feed speed. On receiving the
signal, the servo means sets the feed speed to the first or second
speed employed in the signal recording operation.
[0012] Other objects, features, and advantages of the present
invention will become apparent from the detailed description of the
embodiments in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a block diagram showing an embodiment of the
digital information recording apparatus according to the present
invention;
[0014] FIG. 2 is a block diagram showing an embodiment of a
recording-system encoder according to the present invention;
[0015] FIG. 3 is a diagram showing a configuration example of
signals formatted by the recording-system encoder;
[0016] FIG. 4 is a diagram showing a configuration example of an
identification (ID) code;
[0017] FIGS. 5A to 5E are timing charts showing relationships
between rotary periods of the drum and timings of record signals in
the embodiment of FIG. 1;
[0018] FIG. 6 is a diagram showing track patterns on a magnetic
tape;
[0019] FIG. 7 is a block diagram showing an embodiment of the
digital information reproducing apparatus according to the present
invention;
[0020] FIG. 8 is a block diagram showing a configuration I example
of a reproducing-system decoder according to the present
invention;
[0021] FIGS. 9A to 9E are timing charts showing relationships
between rotary periods of the drum and timings of record
signals;
[0022] FIG. 10 is a block diagram showing another configuration
example of the recording-system encoder according to the present
invention;
[0023] FIG. 11 is a block diagram showing another configuration
example of the reproducing-system decoder according to the present
invention;
[0024] FIG. 12 is a block diagram showing still another embodiment
of the digital information recording apparatus according to the
present invention;
[0025] FIGS. 13A to 13G are timing charts showing relationships
between rotary periods of the drum and timings of record signals in
the embodiment of FIG. 12;
[0026] FIG. 14 is a block diagram showing still another embodiment
of the digital information reproducing apparatus according to the
present invention;
[0027] FIG. 15 is a block diagram showing still another embodiment
of the digital information recording apparatus according to the
present invention;
[0028] FIG. 16 is a block diagram showing further another
embodiment of the digital information reproducing apparatus
according to the present invention; and
[0029] FIG. 17 is a block diagram showing still another embodiment
of the digital information reproducing apparatus according to the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Next, description will be given of embodiments of the
present invention by reference to the drawings.
[0031] FIG. 1 is a block diagram showing an embodiment of the
digital information recording apparatus according to the present
invention. In the diagram, reference numerals 1 and 2 indicate
input terminals, a numeral 11 denotes a change-over switch, a
numeral 21 stands for a recording signal::selector, a numeral 22
designates an identifier signal generator, a numeral 30 indicates a
recording-system encoder, numerals 41 and 42 denote record
amplifiers, a numeral 50 represents a rotary drum, numerals 51 to
54 designate magnetic heads, a numeral 60 indicates a magnetic
tape, and a numeral 70 indicates a servo circuit. Incidentally, in
association with the magnetic heads 51 to 54, the positive and
negative signs (+) and (-) indicate positive and negative azimuths,
respectively.
[0032] Operation of this embodiment will be next described.
[0033] In FIG. 1, to the input terminal 1, there is inputted a
digital information signal Si having a high transmission rate (of,
for example, 20 megabits per second (Mbps) to 40 Mbps) such as a
digital HDTV signal of the ATV system or a digital SDTV signal
obtained by achieving time-division multiplex operation for a
plurality of programs in the "Direct TV" system described above. On
the other hand, supplied to the input terminal 2 is a digital
information signal S2 having a low transmission rate (of, for
example, 5 Mbps to 10 Mbps) such as a digital SDTV signal separated
by selecting one of the plural programs in the "Direct TV" system.
These signals S1 and S2 undergo selection by the change-over switch
such that either one thereof is inputted as a record signal SS to
the recording-system encoder 30.
[0034] The recording signal selector 21 selects as the record
signal SS, the digital information signal S1 of a high transmission
rate or the digital information signal S2 of a low transmission
rate to output a control signal CR therefrom. The identifier signal
generator 22 receives the control signal CR to generate an
identifier signal DS to identify whether the recorded signal is S1
or S2 and then supplies the signal DS to the recording system
encoder 30.
[0035] FIG. 2 shows a block diagram showing a specific example of
the recording-system encoder 30. In FIG. 2, a reference numeral 31
indicates an interface circuit, a numeral 32 denotes a memory
circuit, a numeral 33 stands for a parity generator circuit, a
numeral 34 represents a record signal generator circuit, a numeral
35 indicates an 8-10 modulator circuit, and a numeral 36 denotes a
timing circuit.
[0036] The inputted signal SS and identification signal DS are
stored in the memory circuit 32 via the interface circuit 31.
[0037] In the parity generator circuit 33, parity is generated from
the data items SS and DS stored in the memory circuit 32 to be then
accumulated in the memory circuit 32. The record signal generator
circuit 34 reads the data and parity from the memory circuit 32,
adds a synchronizing code and an identification (ID) code thereto,
and then outputs therefrom two channels of signals in a block
format shown in FIG. 3. In this step, an interleaving process is
also carried out.
[0038] FIG. 4 shows a configuration example of the identification
(ID) code, which includes such control information items as a track
number to identify a record track, a block number to identify a
position in the track, and a record time and a program number on a
tape as well as parity to detect and correct errors therein. In
this connection, the identifier signal DS is inserted into control
information of the identification (ID) code.
[0039] The two channels of signals which are thus formatted through
the interleaving operation, addition of the synchronizing code,
identification (ID) code, and error correction code, and block
forming operation are fed to the 8-10 demodulator circuit 35 to be
subjected to a so-called 8-10 demodulation method in which the
signals are classified into eight-bit groups. Each 8-bit group is
converted into 10-bit data so as to limit the maximum run length,
thereby attaining two channels of record signals SR1 and SR2. On
receiving the control signal CR, the timing circuit 36 controls
timings of the interface circuit 31, memory circuit 32, parity
generator circuit 33, record signal generator circuit 34, and 8-10
modulator circuit 35 and then outputs a reference signal CK to the
servo circuit 70.
[0040] The two channels of record signals SR1 and SR2 are then
delivered respectively via the record amplifiers 41 and 42 to the
magnetic heads 51 and 52 and magnetic heads 53 and 54,
respectively. In this regard, the magnetic heads 51 and 52 and
magnetic heads 53 and 54 are arranged over the rotary drum 50 at
positions being close to each other and opposing to each other with
an angle of 180.degree. and with a predetermined gap therebetween
(for example, on the same head bases).
[0041] In this situation, when the digital information signal S1 of
a high transmission rate is to be recorded, the servo circuit 70
receives the reference signal CK from the timing circuit 36 to
control the rotary drum 50 to rotate at a first rotation speed R1
and the magnetic tape 60 to be fed at a first feed speed V1 so as
to conduct a 4-track azimuth recording operation in which the two
channels of record signals SR1 and SR2 supplied via the record
amplifiers 41 and 42 are recorded on four tracks in one rotation of
the rotary drum 50 by alternately utilizing the magnetic heads 51
and 52 and magnetic heads 53 and 54.
[0042] FIGS. 5A to 5E are timing charts showing relationships
between rotations of the rotary drum 50 and timings of the Record
signals SR1 and SR2 in the operation above. In the diagram, FIG. 5A
shows timing of the rotary drum 50 and FIGS. 5B and 5C show timings
of the record signals SR1 and SR2, respectively.
[0043] In FIG. 5A, in the periods of a low level, data is recorded
by the magnetic heads 51 and 52; whereas, in the periods of a high
level, data is recorded by the magnetic heads 53 and 54. When
recording the signal S1 of a high transmission rate, the record
signals SR1 and SR2 are successively recorded as shown in FIGS. 5B
and 5C.
[0044] FIG. 6 shows track patterns drawn on the magnetic tape in
the operation. As shown in FIG. 6, the record signals SR1 and SR2
are written respectively on a (-) azimuth track 61 and a (+)
azimuth track 62 of the magnetic tape 60. In this regard, Tp
indicates a track pitch.
[0045] On the other hand, when recording the signal S2 of a low
transmission rate, there are outputted from the recording-system
encoder 30, as shown in FIGS. 5D and 5E, two channels of burst-like
recording signals SR1 and SR2 obtained by achieving a 1/N time-axis
compression each time the rotary drum 50 makes N/2 rotations (N is
an integer equal to or more than two). In this operation, when the
ratio between the digital information signals S1 and S2 is assumed
to be 1 to 1/n (n is a real number equal to or more than two), the
time-axis compression ratio is set to an integer nearest to the
transmission rate n. Furthermore, in case where N.noteq.n, by
adding dummy data to the signals, the recording rate of the
burst-like record signals SR1 and SR2 can be set to be
substantially equal to the recording rate employed when the digital
information signal S1 is recorded.
[0046] On receiving the reference signal CK, the servo circuit 70
respectively controls the rotary drum 50 to rotate at a second
rotation speed R2 (R2.apprxeq.R1) almost equal to the first rotary
speed R1 and the magnetic tape 60 to be fed at a second feed speed
V2 (V2.apprxeq.V1/N) substantially equal to 1/N of the first feed
speed V1. Thereafter, as shown in FIGS. 5D and 5E, the two channels
of recording signals SR1 and SR2 formed in the burst-like format by
the time-axis compression are written on the magnetic tape 60 by
using only the magnetic heads 51 and 52 or by alternately using the
magnetic heads 51 and 52 and the magnetic heads 53 and 54.
[0047] The burst-like record signals SR1 and SR2 are respectively
recorded on (-) and (+) azimuth tracks 61 and 62 as described
above, thereby achieving a 4-track azimuth recording operation in N
rotations of the rotary drum 50. In consequence, track patterns are
formed as shown in FIG. 6 namely, the record signals SR1 and SR2
are written respectively on (-) and (+) azimuth tracks 61 and 62 of
the magnetic tape 60.
[0048] In this connection, although the time-base compression ratio
N is set to three in FIGS. 5D and 5E for simplicity of explanation,
the value N needs to only be set to an integer. That is, as shown
in the diagram, when N takes an odd number, the magnetic heads 51
and 52 and magnetic heads 53 and 54 are alternately used; whereas,
when N is an even number, there are used only the magnetic heads 51
and 52 to record the signals undergone the time-axis compression.
Consequently, the 4-track azimuth recording operation in N
rotations of the rotary drum 50 is not changed in any case. In
consequence including the case of N=1, namely, the case of the
digital information signal S1 of a high transmission rate, there
can be used a common track format of signals on the magnetic tape
60. There exists a different point that the total period of time
available for the recording of signals on the magnetic tape 60 is
increased or decreased in accordance with the time-axis compression
ratio N. Namely, for example, digital HD video signals of high
quality or digital SD video signals of many programs can be
recorded in a standard period of time. Moreover, if only one
program of digital SD video signals is to be recorded, there can be
conducted a long-period recording operation.
[0049] FIG. 7 is a block diagram showing an embodiment of the
digital information reproducing apparatus according to the present
invention. In this diagram, reference numerals 101 and 102 indicate
reproduction amplifiers, a numeral 110 denotes a reproducing-system
decoder, a numeral 121 stands for a record signal judge unit, a
numeral 131 represents a change-over switch, and numerals 141 and
142 indicate output terminals. Components corresponding to those of
FIG. 1 are assigned with the same reference numerals.
[0050] Next, operation of the embodiment will be described.
[0051] In FIG. 7, two channels of signals SP1 and SP2 reproduced by
the magnetic heads 51 and 52 and magnetic heads 53 and 54 and
amplified by the reproduction amplifiers 101 and 102 are
respectively supplied to the reproducing-system decoder 110. In the
decoder 110, the reproduction signals SP1 and SP2 are subjected to
a de-formatting operation reverse to that of the recording-system
encoder 30 to be transformed into the original digital information
signals.
[0052] FIG. 8 is a block diagram showing a concrete example of the
reproducing-system decoder 110. In FIG. 8, a reference numeral 111
indicates an 8-10 demodulator circuit, a numeral 112 designates a
block reproducing circuit, a numeral 113 stands for a memory
circuit, a numeral 114 represents an error correction circuit, a
numeral 115 denotes a reproduction signal output circuit, and a
numeral 116 indicates a timing circuit.
[0053] In the diagram, the reproduction signals SP1 and SP2
inputted thereto are fed to the 8-10 demodulator circuit 111 to
undergo equalization, code discrimination, and demodulation to be
fed to the block reproducing circuit 112. On the occasion, as the
equalizing method of the 8-10 demodulator circuit 111, there may be
employed, for example, an integral equalization (integral
detection) in which differential characteristics of the reproducing
system are compensated for by integration. In the block reproducing
circuit 11, the synchronizing and identification (ID) codes are
detected such that reproduced data is stored at a predetermined
position in the memory circuit 113 according to a track number and
a block number in the identifier signal.
[0054] The error correction circuit 114 corrects errors in the
reproduced data in accordance with parity stored in the memory
circuit 113. The reproduction signal output circuit 115 reads the
corrected reproduction data from the memory circuit 113 to output
therefrom the original digital information signal SS and identifier
signal DS. In this operation, a deinterleaving process is performed
in association with the interleaving process of the recording side.
The timing circuit 116 controls timings of the 8-10 demodulator
circuit 111, block reproducing circuit 112, error correction
circuit 114, and reproduction signal output circuit 115 and outputs
the reference signal CK to the servo circuit 70.
[0055] In this situation, the record signal judge circuit 121
receives the identifier signal DS from the reproducing-system
decoder 110 to decide whether the record reproduction signal is the
digital information S1 or S2 to output a control signal CP so as to
control the change-over switch 131 in accordance with the signal
CP. Thereafter, when the record reproduction signal is decided to
be the digital information signal S1 of a high transmission rate or
the digital information signal S2 of a low transmission rate, the
digital information signal SS is outputted from the output terminal
141 or 142, respectively.
[0056] In addition, on receiving the reference signal CK, the servo
circuit 70 controls the rotary drum 50 to rotate at a first or
second rotary speed R1 or R2 and the magnetic tape 60 to be fed at
a first or second feed speed V1 or V2, respectively.
[0057] Incidentally, at the initial point of reproduction, the
identifier signal is not detected and control of the rotary drum 50
and magnetic tape is undetermined. In this case, for example,
control is effected to set the rotation speed of the rotary drum 50
and the feed speed of the magnetic tape 60 respectively to the
first rotation speed R1 and first feed speed V1 such that the speed
control need only be altered when the identifier signal is
detected. This is because the recording rates are substantially
equal to each other and the track format is commonly used and hence
even when a tape on which digital information signals of a low
transmission rate are recorded is reproduced in the above manner,
the reproducing-system decoder 110 conducts a normal operation to
appropriately detect the identifier signal.
[0058] As above, according to the embodiment, two kinds of digital
information signals having different transmission rates, for
example, HDTV signals encoded through digital compression and SDTV
signals similarly encoded through digital compression or SDTV
signals of a plurality of programs encoded through digital
compression and undergone time-division multiplexing operation and
digital SDTV signals of a program selected and separated from the
plural programs can be selected and recorded on a medium so as to
be automatically judged for reproduction thereof by the single-head
configuration.
[0059] Incidentally, in conjunction with the embodiment, there has
been described a method of inserting the identifier signal into
record data. However, the present invention is not restricted by
the embodiment. Namely, the identifier signal may be recorded a
plurality of times on a control track prepared to control
tracking.
[0060] Additionally, in the example of the embodiment, the
effective wrap angle of the magnetic tape 60 on the rotary drum is
180.degree., which does not restrict the present invention. For
example, the present invention is also applicable to a case of the
effective angle less than 180.degree..
[0061] FIGS. 9A to 9E are timing charts showing relationships
between rotations of the rotary drum 50 and timings of the record
signals SR1 and SR2 in the situation. Like FIGS. 5A to 5E, FIG. 9A
shows timings of the rotary drum 50, FIGS. B and C presents timings
of the record signals SR1 and SR2 when recording the digital
information signal S1 of a high transmission rate, and FIGS. D and
E show timings of the record signals SR1 and SR2 when recording the
digital information signal S2 of a low transmission rate.
[0062] In case where the signal S1 is to be recorded, the record
signals SR1 and SR2 which are undergone a time-base compression at
an effective wrap angle el (e.g., 90.degree. to 175.degree.) each
time the rotary drum 50 makes a half rotation are outputted from
the recording-system encoder 30 to be recorded as shown in FIGS. 9B
and 9C. On the other hand, when the signal S2 is to be recorded,
the record signals SR1 and SR2 which are compressed through a
time-base compression to 1/N of the original signals each time the
rotary drum 50 makes N/2 rotations and undergone a time-base
compression at an effective angle .theta.2
(.theta.2.apprxeq..theta.1) are outputted from the recording-system
encoder 30 to be recorded as shown in FIGS. 9D and 9E.
[0063] Moreover, although the 8-10 modulation method is employed as
a method of modulating record data in the embodiment, the present
invention is not restricted by the method. Namely, there may be
adopted an interleaved scrambled non-return-to-zero inverse
(I-S-NRZI) modulation method.
[0064] FIG. 10 is a block diagram showing another specific
embodiment of the recording-system encoder according to the present
invention. In FIG. 10, a reference numeral 37 indicates an I-S-NRZI
modulator circuit and components corresponding to those of FIG. 2
are assigned with the same reference numerals. Adoption of the
I-S-NRZI modulation method is a feature of the specific
example.
[0065] In the I-S-NRZI modulation method, record data is first
randomized by pseudo random signals such that the randomized record
data is Ex-ORed with a demodulation signal having a delay of two
bits. When compared with the 8-10 modulation method, this method
has an aspect that the final recording rate is reduced to {fraction
(8/10)} of the original recording rate. On the other hand,
according to the I-S-NRZI modulation method, although there can be
recorded signals containing a spectrum up to a low frequency zone,
the spectrum of the low frequency zone cannot be reproduced due to
differential characteristics of the reproducing system. When the
signals are equalized in the integral equalization method, there
arises a problem of deterioration of the signal-to-noise (S/N)
ratio. In this situation, when using the I-S-NRZI modulation
method, it is necessary for the reproducing system to utilize the
an equalization (detection) method not using integration.
[0066] FIG. 11 is a block diagram showing another concrete example
of the reproducing-system decoder 110 according to the present
invention corresponding to the recording-system encoder 30 shown in
FIG. 10. In FIG. 11, a reference numeral 111 indicates a partial
response class IV (PR4) detector circuit and the components
corresponding to those of FIG. 8 are assigned with the same
reference numeral.
[0067] In the diagram, the PR4 detector circuit 117 detects
randomized record data in the regenerated signals and then
de-scrambles the randomized record data. To detect the data, there
is naturally used the PR4 detection method. In this method, the
overall impulse response of the recording and reproducing systems
is represented as (1,0,-1). Since integration is unnecessary, there
is advantageously attained a feature of a satisfactory S/N
ratio.
[0068] FIG. 12 is a block diagram showing still another embodiment
of the digital information recording apparatus according to the
present invention. In FIG. 12, a reference numeral 3 denotes an
input terminal and components corresponding to those of FIG. 1 are
assigned with the same reference numerals.
[0069] The embodiment has a feature that three kinds of digital
information signals respectively having high, middle, and low
transmission rates are selectively recorded. Operation of the
embodiment will now be described.
[0070] In the diagram, in a similar manner as for the embodiment
shown in FIG. 1, a digital information signal S1 of a high
transmission rate (e.g., 20 Mbps to 40 Mbps) and a digital
information signal S2 of a middle trans-mission rate (e.g., 5 Mbps
to 10 Mbps) are supplied to the input terminals 1 and 2,
respectively. Moreover, a digital information signal S3 of a low
transmission rate (e.g., 1 Mbps to 2 Mbps) of a digital SDTV signal
encoded by a further efficient digital compression is fed to the
input terminal 3. These signals S1, S2, and S3 are then subjected
to selection or changed-over by the change-over switch 11 such that
either one thereof is inputted as a record signal SS to the
recording-system encoder 30.
[0071] The record signal selector 21 selects as the record signal
SS the signal S1 of a high transmission rate, the signal S2 of a
middle transmission rate, or the signal S3 of a low transmission
rate and then outputs the control signal CR. On receiving the
control signal CR, the identifier signal generator 22 generates an
identifier signal DS to identify whether the recorded signal is S1,
S2, or S3 to supply the signal DS to the recording-system encoder
30.
[0072] In the encoder 30, there are conducted processes similar to
those of the embodiment shown in FIGS. 1 and 2. Namely, in
accordance with the respective signals, the signals are converted
into two channels of recording signals SR1 and SR2 at timings shown
in FIGS. 13A to 13G.
[0073] In this connection, FIG. 13A shows rotation timing of the
rotary drum 50, FIGS. 13B and 13C respectively show timings of the
record signals SR1 and SR2 when the signal S1 is recorded, FIGS.
13D and 13E respectively show timings of the record signals SR1 and
SR2 when the signal S2 is recorded, and FIGS. 13F and 13G
respectively show timings of the record signals SR1 and SR2 when
the signal S3 is recorded.
[0074] In FIG. 13A, the recording is conducted by the magnetic
heads 51 and 52 and magnetic heads 53 and 54 respectively during
the low-level and high-level periods in a manner similar to that of
the embodiment shown in FIG. 1. Moreover, when recording the signal
S1 of a high-transmission rate, record signals SR1 and SR2 are
consecutively outputted from the recording-system encoder 30 as
shown in FIGS. 13B and 13C.
[0075] On the other hand, when the signal S2 of a
middle-transmission rate is to be recorded, two channels of
burst-like recording signals SR1 and SR2 which are compressed on a
time axis to 1/N of the original signal each time the rotary drum
makes N/2 rotations (N is an integer equal to or more than two) are
delivered from the recording-system encoder 30 as shown in FIGS.
13D and 13E. On this occasion, when the ratio between the
transmissions respectively of the signals S1 and S2 is assumed as
1:1/n (n is a real number equal to or more than two), the time-base
compression ratio N is set to an integer nearest to the rate n.
Moreover, in case where N.noteq.n, for example, by adding dummy
data to the signals, the recording rate of the burst-like record
signals SR1 and SR2 is set to be substantially equal to the
recording rate at which the signal S1 of a high transmission rate
is recorded.
[0076] Similarly, when recording the signal S3 of a
low-transmission rate, two kinds of burst-like record signals SR1
and SR2 which are compressed on a time axis to 1/M of the original
signals each time the rotary drum makes M/2 rotations (M is an
integer equal to or more than two) are delivered from the
recording-system encoder 30 as shown in FIGS. 13F and 13G. In this
situation, when the ratio between the transmissions respectively of
the signals S1 and S3 is assumed as 1:1/m (m is a real number equal
to or more than two), the time-base compression ratio M is set to
an integer nearest to the rate m. Furthermore, in case where
M.noteq.m, for example, by adding dummy data to the signals, the
recording rate of the burst-like record signals SR1 and SR2 is set
to be almost equal to the recording rate employed to record the
signal S1 of a high transmission rate.
[0077] These two channels of recording signals SR1 and SR2 are then
supplied respectively via the record amplifiers 41 and 42 to the
magnetic heads 51 and 52 and magnetic heads 53 and 54,
respectively.
[0078] When the signal S1 is to be recorded, the servo circuit 70
receives the reference signal CK from the recording-system encoder
30 to achieve a control operation to set the rotation speed of the
rotary drum 50 and the feed speed of the magnetic tape 60
respectively to a first rotation speed R1 and a first feed speed V1
so as to accomplish four-track azimuth recording of the record
signals SR1 and SR2 shown in FIGS. 13B and 13C for each revolution
of the rotary drum 50 by alternately using the magnetic heads 51
and 52 and magnetic heads 53 and 54.
[0079] On the other hand, when recording the signal S2, the servo
circuit 70 receives the reference signal CK from the encoder 30 to
control the rotation speed of the rotary drum 50 and the feed speed
of the magnetic tape 60 to be set respectively to a second rotation
speed R2 similar to the first rotation speed R1 (R2.apprxeq.R1) and
a second feed speed V2 similar to 1/N of the first feed speed V1
(V2.apprxeq.V1/N). Thereafter, the servo circuit 70 conducts
four-track azimuth recording of the record signals SR1 and SR2
shown in FIGS. 13D and 13E in every N turns of the rotary, drum 50
by use of the magnetic heads 51 and 52.
[0080] In the similar manner, when recording the signal S3, the
servo circuit 70 receives the reference signal CK from the encoder
30 to control the rotation speed of the rotary drum 50 and the feed
speed of the magnetic tape 60 to be set respectively to a third
rotation speed R2 similar to the first rotation speed R1
(R3.apprxeq.R1) and a third feed speed V3 similar to 1/M of the
first feed speed V1 (V3.apprxeq.V1/M). The servo circuit 70 then
conducts four-track azimuth recording of the record signals SR1 and
SR2 shown in FIGS. 13F and 13G by the magnetic heads 51 and 52 each
time the rotary drum 50 makes M rotations.
[0081] As above, the record signals SR1 and SR2 are recorded
respectively on the minus (-) and plus (+) azimuth tracks 61 and 62
in a similar manner as for the track patterns shown in FIG. 6. This
makes it possible to use the common track format on the magnetic
tape.
[0082] FIG. 14 is a block diagram showing further another
embodiment of the digital information reproducing apparatus
according to the present invention. In this diagram, a reference
numeral 143 indicates an output terminal and components
corresponding to those of FIG. 7 are assigned with the same
reference numerals.
[0083] The embodiment has a feature that three kinds of digital
information signals having high, middle, and low transmission rates
selected and recorded in association with the recording apparatus
shown in FIG. 12 are automatically judged for reproduction
thereof.
[0084] Next, description will be given of operation of the
embodiment.
[0085] In FIG. 14, two channels of signals SP1 and SP2 reproduced
by the magnetic heads 51 and 52 and magnetic heads 53 and 54 and
amplified by the reproduction amplifiers 101 and 102 are
respectively supplied to the reproducing-system decoder 110 to
undergo a decoding process of the reproducing system in a similar
fashion as for the embodiment shown in FIG. 7 so as to restore the
original digital information signal SS and control information DS.
Similarly, the record signal judge circuit 121 receives the
identifier signal DS to decide whether the record reproduction
signal is the digital information S1, S2, or S3 and accordingly
controls the change-over switch 131. In addition, on receiving the
reference signal CK from the decoder 110, the servo circuit 70
respectively controls the rotary drum 50 to set the rotary speed to
a first, second, or third rotation speed R1, R2, or R3 and the feed
speed of the magnetic tape 60 to a first, second, or third feed
speed V1, V2, or V3, respectively.
[0086] Thereafter, when the digital information signal SS is the
signal S1, S2, or S3, the signal is outputted respectively from the
output terminal 141, 142, or 143 via the change-over switch
131.
[0087] As above, according to the embodiments shown in FIGS. 12 and
14, three kinds of digital information signals having different
transmission rates can be selected and recorded to be thereafter
automatically judged for reproduction thereof by the single-head
configuration.
[0088] Incidentally, in the embodiments above, the transmission,
recording, and reproducing speeds of digital information are fixed.
However, the present invention is not restricted by the
embodiments. For example, the present invention is applicable to a
system in which the transmission, recording, and reproducing speeds
of digital information are increased (more specifically, digital
information is compressed on a time axis for transmission and
recording thereof). In the signal reproduction, there is reproduced
information having the original transmission rate (through
expansion thereof on a time axis).
[0089] FIG. 15 is a block diagram showing still another embodiment
of the digital information recording apparatus according to the
present invention in association with the system above.
[0090] In the diagram, a digital information signal S1 of a high
transmission rate compressed on a time axis to 1/K (K is an integer
equal to or more than two) of the original signal and a digital
information signal S2 of a low transmission rate compressed on a
time axis to 1/L (L is an integer equal to or more than two) of the
original signal are inputted to the input terminals 1 and 2,
respectively. Thereafter, the recording of the signals is
accomplished in the same manner as for the embodiment shown in FIG.
1. In this situation, it is to be appreciated that control
information denoting that the record signal is a signal undergone a
time-base compression is inserted in the identifier signal from the
identifier signal generator 22.
[0091] FIG. 16 is a block diagram showing still another embodiment
of the digital information reproducing apparatus according to the
present invention in association with the system above.
[0092] In the diagram, on receiving the reference signal CK from
the decoder 110 the servo circuit 70 achieves control operations in
the similar manner as for the embodiment shown in FIG. 7. When
reproducing the signal S1 undergone the 1/K time-axis compression,
the servo circuit 70 controls the rotary drum 50 to rotate at a
rotation speed (R1/K) equal to 1/K of the recording rotation
speed-and the feed speed of the magnetic tape 60 to be set to a
feed speed (V1/K) equal to 1/K of the recording feed speed. on the
other hand, when reproducing the signal S2 undergone the 1/L
time-axis compression, the servo circuit 70 controls the rotary
drum 50 to respectively set the rotation speed to a rotary speed
(R2/L) equal to 1/L of the recording rotation speed and the feed
speed of the magnetic tape 60 to a feed speed (V2/L) equal to 1/L
of the recording feed speed.
[0093] In the reproducing operation, when each of the rotation
speed of the rotary drum 50 and the feed speed of the magnetic tape
60 is set operation to 1/K or 1/L of the associated speed used in
the recording operation, the magnetic heads 51 and 52 and magnetic
heads 53 and 54 draw the same scanning tracks as those of the
recording operation and hence there are reproduced signals
multiplied by K or L on a time axis. The other operations are the
same as those of the embodiment shown in FIG. 7. Outputted
respectively from the output terminals 141 and 142 are a digital
information signal S1' of a high transmission rate having the
original speed (multiplied by K on a time axis) and a digital
information signal S2' of a low transmission rate having the
original speed (multiplied by L on a time axis).
[0094] As above, according to the embodiment, in a system in which
two kinds of digital information signals having different transfer
rates are selected and recorded to be thereafter automatically
reproduced by the single-head configuration, the recording period
of time can be reduced.
[0095] FIG. 17 is a block diagram showing further another
embodiment of the digital information reproducing apparatus
according to the present invention in association with a system in
which the recording time is minimized in the same fashion as for
the embodiment shown in FIG. 16.
[0096] This embodiment differs from that shown in FIG. 16 in that
the servo circuit 70 of FIG. 17 controls the rotary drum 50 to set
the rotation speed to the first or second rotation speed R1 or R2
used in the recording operation. When the rotation speed of the
rotary drum 50 is set to 1/K or 1/L, the frequency band of
reproduced signals is lowered to 1/K or 1/L of that obtained in the
recording operation and hence the reproduction output level is
decreased. In this situation, if the S/N ratio is sufficient, there
will not arise any problem. However, when the value of K or L is
increased, the S/N ratio may possibly become insufficient.
[0097] To cope with the difficulty in the reproduction, according
to the embodiment, the rotary speed of the rotary drum 50 is set to
that of the recording operation to enlarge the frequency band of
reproduced signals, thereby guaranteeing the reproduction output
level.
[0098] Incidentally, the scanning tracks of the magnetic heads 5-1
and 52 and magnetic heads 53 and 54 in the reproduction are
different from those of the recording operation in this embodiment.
However, since each track is scanned substantially K or L times, it
is possible to obtain a sequence of signals through the scanning
operations.
[0099] That is, in the reproducing-system decoder 110 shown in FIG.
8 or 11, the reproduction signals SP1 and SP2 inputted thereto are
subjected to processes of equalization, code discrimination, and
demodulation in the 8-10 demodulator circuit 111 and/or the PR4
detector circuit 111 to be then supplied to the block regenerating
circuit 112. In the circuit 112, a synchronizing code and an
identification (ID) code are detected such that reproduction data
is stored at a predetermined position of the storage circuit 113
according to a track number and a block number in the
identification (ID) code.
[0100] In the error detection circuit 114, errors contained in the
reproduction data are corrected in accordance with parity stored in
the storage circuit 113 and there is generated a pointer indicating
the error state, thereby storing the pointer in the memory circuit
113. In this operation, although data having the same track and
block numbers is inputted L times to the storage circuit 113, data
containing the smallest number of errors is finally stored therein
in accordance with the pointer. In the reproduction signal output
circuit 115, reproduction data undergone the error correction and
stored in the memory circuit 113 are sequentially read therefrom in
a sequence of the track and block numbers.
[0101] As above, there are reproduced the original digital
information signals SS expanded in accordance with the original
speed on a time axis. In the scanning operation above, the
reproduction output level can be guaranteed. Moreover, the track is
scanned K or L times, which leads to an advantage that any precise
tracking control operation is not required.
[0102] In conjunction with the embodiment above, description has
been given of a case in which two or three kinds of digital
information signals having different transmission rates are
recorded and reproduced. However, the present invention is not
restricted by the embodiment. It is to be appreciated that digital
information signals of an arbitrary number of kinds can be selected
and recorded to be thereafter automatically judged for reproduction
thereof by the single-head configuration.
[0103] As described above, according to the present invention, a
plurality of digital information signals having different
transmission rates can be selected and recorded to the thereafter
automatically judged for reproduction thereof by the single-head
configuration.
[0104] While the present invention has been described with
reference to the particular illustrative embodiments, it is not to
be restricted by those embodiments but only by the appended claims.
It is to be appreciated that those skilled in the art can change or
modify the embodiments without departing from the scope and spirit
of the present invention.
* * * * *