Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
2000-08-23
2002-02-12
Sniezek, Andrew L. (Department: 2651)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06347182
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a magnetic recording and reproducing apparatus such as a time lapse magnetic recording and reproducing system (hereinafter referred to as a “time lapse VTR”) for recording and reproducing picture signals while intermittently skipping frames, which is used for monitoring, burglar-proofing, and so forth.
Recently, a time lapse VTR which can make long time recording such as 720 hours on a single tape by sequentially switching picture signals from a plurality of video cameras and recording them while intermittently skipping frames has gained a wide application so as to simultaneously monitor various places such as plants, sites of construction, shops, etc., in place of guards. When any accident occurs, valuable information can be acquired by quickly reproducing the picture signals recorded on the tape.
JP-A-62-295581, for example, discloses a time lapse VTR which counts the number of tracks on a magnetic tape at the time of reproduction of the tape, extracts reproduction signals from the tape in one field or frame unit whenever the count value becomes equal to the number of video cameras, alternately records the outputs of a plurality of video cameras in one field or frame unit on the same magnetic tape, takes out the outputs of the desired video camera or cameras in one field or frame unit from the magnetic tape at the time of reproduction, and can thus confirm correctly the recorded content.
Next, the construction of a time lapse VTR using a video cassette tape of a VHS system and available commercially in the past will be explained by way of example with reference to the accompanying drawings.
FIG. 1
shows an example of the construction using the conventional time lapse VTR. In
FIG. 1
, reference numeral
1
denotes a time lapse VTR,
2
is a switcher and
3
a
to
3
d
are video cameras. Picture signals from the video cameras
3
a
to
3
d
(A, B, C and D ch (channels), respectively) are sequentially switched in a field or frame unit by a picture switching circuit
4
of the switcher
2
and are supplied to the time lapse VTR
1
. Though the switcher
2
is shown separately disposed in another apparatus, it may be assembled into the time lapse VTR
1
. A chrominance signal in the inputted picture signals is converted to a low band signal by a color low-pass conversion circuit
7
in the time lapse VTR
1
, while a luminance signal is subjected to frequency modulation by an FM modulation circuit
8
. The outputs of these circuits
7
and
8
are added by an addition circuit
9
, and each channel is sequentially recorded by four magnetic heads H
1+
(
12
), H
2−
(
13
), H
3−
(
14
) and H
4+
(
15
) mounted on a cylinder
11
on a magnetic tape
16
′ through a recording amplifier
10
. In this case, operation modes include a normal speed mode (33.33 mm/sec in a standard mode of the VHS system, for example) for recording and reproduction while the tape is continuously transported run at a normal speed, and besides an intermittent recording/reproduction mode (recording while the tape is stopped) for long time recording by intermittently transporting the tape. During reproduction, the reproduction head signals from the magnetic heads H
1+
(
12
), H
2−
(
13
), H
3−
(
14
) and H
4+
(
15
) are amplified by preamplifiers
16
,
17
,
18
and
19
, respectively, are then passed through switch circuits
20
,
21
,
22
, are converted to chrominance signals and luminance signals restored to their original bands by a color high-pass conversion circuit
23
and an FM demodulation circuit
24
, and are further added together by an addition circuit
25
to provide reproduction picture signals. System control means
27
activates a servo circuit
30
which controls the cylinder
11
, a control head
28
and a capstan shaft
29
in accordance with an operation mode inputted by a user through mode setting/input means
26
, and lets it control the operation condition of the time lapse VTR. The system control means
27
activates a change-over circuit
31
, selects one of the outputs of the switch circuits
20
and
21
as the output of the switch circuit
22
in the normal speed reproduction mode of the tape, and selects the one of the outputs of the switch circuits
20
and
21
which has the higher level as the output of the switch circuit
22
under control of a level detection circuit
32
during a search reproduction mode in which the recorded content can be watched more quickly than the normal speed.
The switcher
2
divides the picture signal from the time lapse VTR
1
into field units by A/D means
33
, an image memory
34
, D/A means
35
and memory control means
36
which controls these circuit elements and a reproduction picture of a desired channel can thus be obtained on a TV monitor
38
in accordance with the output of reproduction channel setting means
37
.
Here, when a tape which is intermittently recorded is reproduced intermittently, a substantially flat and satisfactory reproduction head signal such as shown in (e) or (f) in
FIG. 2
can be obtained on the basis of a SW
30
signal
39
representing the period in which the magnetic heads
12
to
15
are in contact with the tape as shown in (b) in FIG.
2
. Needless to say, a substantially flat and satisfactory reproduction head signal can likewise be obtained as shown in (e) or (f) in
FIG. 2
when a tape recorded at the normal speed is reproduced at the normal speed. When the tape recorded intermittently is reproduced at the normal speed and this is watched somewhat quickly, a head reproduction head signal above a necessary level can be obtained, although the waveform becomes diamond-like as shown in
FIG. 3
because the tilt of the recording track and the reproduction trace is different by one track. Accordingly, the reproduction picture of each of the A, B, C and D channels selected through the switcher
2
can be obtained satisfactorily in both of these cases.
In the conventional time lapse VTR described above, however, the reproduction trace orbit of the magnetic heads stretches over six tracks at the time of 5-time speed search as shown in
FIG. 4
by way of example in a search reproduction mode in which a tape of intermittent travel multi-channel recording is transported at a high speed. In this case, the outputs of the switch circuits
20
and
21
become diamond-like as shown in (f) and (g) in
FIG. 5 and a
level detection circuit
32
selects the output which has the higher level, so that the output of the switch circuit
22
becomes such as shown in (h) in FIG.
5
. Assuming that 4-channel picture signals are recorded by four cameras, the output of the switch circuit
22
includes A, B, C and D channels that partially exist in one reproduction field as shown in (i) in FIG.
5
. In other words, each channel is reproduced partially on the TV monitor
38
as shown in
FIG. 6
in such a manner as to correspond to the of output of the switch circuit
22
shown in (h) in FIG.
5
. Eventually, the A, B, C and D channels are multiplexed as shown in FIG.
7
and the resulting picture becomes extremely difficult to watch.
SUMMARY OF THE INVENTION
It is a main object of the present invention to provide a VTR which makes it possible to recognize and confirm easily and correctly a reproduction picture not only when a tape intermittently recorded is reproduced intermittently or at a normal speed but also in search reproduction for watching more quickly a recorded content, irrespective of recording modes such as intermittent recording and normal speed recording.
It is another object of the present invention to watch simultaneously, quickly and satisfactorily reproduction pictures of a large number of channels by displaying dividedly pictures of a plurality of channels on a monitor during search reproduction.
It is still another object of the present invention to watch sequentially, quickly and satisfactorily reproduction pictures of a large number of channels by displaying dividedly pictures of a plurality of channels on a ti
Kimura Hiroyuki
Kudo Mitsuru
Okada Yoshinori
Sakae Tetsuo
Takasugi Hajime
LandOfFree
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