JPH0430643B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing device, and in particular, a video signal is recorded on one track.
The PCM audio signal is recorded on the magnetic tape, avoiding crosstalk interference to the playback video signal.
This invention relates to after-recording of audio signals.

[Prior art] Figure 1 shows the PCM on the video signal track extension.
1 is a diagram showing the relationship among a head drum, a rotating magnetic head, and a magnetic tape of a conventional magnetic recording/reproducing apparatus that records audio signals in a time-compressed manner; FIG. In the figure, a magnetic tape 2 runs diagonally around a head drum 1 over an angular interval of about 220 degrees. head drum 1
At the top there are rotating magnetic heads 3 with an angular spacing of 180°.
a and 3b are provided.

FIG. 2 is a block diagram of the main parts of a recording/reproducing transmission system in a conventional magnetic recording/reproducing apparatus. In the figure, the changeover switch 5 is the switch 5a, 5b.
It is a changeover switch for introducing a recording signal into the rotating magnetic heads 3a, 3b or for deriving a reproduction signal from the rotating magnetic heads 3a, 3b. The rotary transformer 4 is composed of transformers 4a and 4b. The input terminal 7 is connected to the rotating magnetic head 3 via the recording amplifier 6, switch 5a, and transformer 4a.
Input terminal 11 is connected to rotating magnetic head 3b via recording amplifier 10, switch 5b, and transformer 4b. Input terminals 7, 11
When recording, the video signal V and the PCM audio signal P are
is applied in time division. Rotation detector (PG1) 3
The rotation detectors (PG2) 30b are arranged around the head drum 1 with an angular interval of 180 degrees. The rotation detector (PG1) 30a and the rotation detector (PG2) 30b are connected to a timing signal generation circuit 31, and the timing signal generation circuit 31 is connected to the changeover switch 5. Rotation detector (PG1) 3
0a, the rotation detector (PG2) 30b detects the rotation of the head drum 1 and outputs a rotation detection pulse,
This pulse is applied to the timing signal generation circuit 31. For example, the timing signal generation circuit is
It consists of a pulse delay circuit made up of multiple mono-multivibrators. The timing signal generation circuit 31 generates the head drum 1 using rotation detection pulses.
A timing signal is generated in synchronization with the rotation of the switch 5, and this signal is applied to the changeover switch 5. The timing signal controls the switching of the changeover switch 5.

The transformer 4a is connected to the output terminal 9 via the switch 5a and the regeneration amplifier 8.
b is connected to the output terminal 13 via the switch 5b and the reproducing amplifier 12. The reproduction amplifiers 8 and 12 are
During reproduction, reproduction signals from the rotating magnetic heads 3a and 3b, which are led out via switches 5a and 5b, are amplified and output to output terminals 9 and 13, respectively. The changeover switch 14 is composed of switches 14a and 14b. Output terminal 9 is connected to output terminal 15 via switch 14a and to output terminal 16 via switch 14b. Further, the output terminal 13 is connected to the output terminal 15 via the switch 14a.
It is connected to the output terminal 16 via 4b. Also,
The timing signal generation circuit 31 is connected to the changeover switch 14
connected to. Timing signal is switch 1
4 and controls the switching of this switch. The changeover switch 14 is connected to the rotating magnetic head 3a,
From the signal reproduced by 3b, a video signal V and a PCM audio signal P are separated and outputted using a timing signal.

Next, the operation of the main parts of this transmission system will be explained. During recording, the magnetic tape 2 is connected to the head drum 1.
It wraps diagonally around and travels at a constant speed in the direction of arrow A in the figure. During recording, the rotating magnetic heads 3a and 3b rotate in the direction of arrow B in the figure in synchronization with a vertical synchronizing signal included in the video signal to be recorded. For example, the rotating magnetic heads 3a and 3b rotate by servo rotation ( (not shown). During recording, a video signal is alternately applied to the rotating magnetic head 3a or 3b for each field in response to a timing signal, and the video signal is recorded on the magnetic tape 2 at a 180° angle as shown in FIG. Furthermore, the first
In the 40° section shown in the figure, the PCM audio signal to be recorded is alternately applied to the rotating magnetic head 3a or 3b by a timing signal. During this period, the rotating magnetic heads 3a and 3b are simultaneously in contact with the magnetic tape 2, and both rotating magnetic heads are forming a transformer adjacent to each other. For example, when the rotating magnetic head 3a starts recording a PCM audio signal and is forming one track, the rotating magnetic head 3b is already forming the latter half of the previous track and is recording a video signal. (See Figure 4). The video signal and PCM audio signal are sent to the rotating magnetic head 3a or 3b in a time-sharing manner according to the timing signal.
is applied to That is, during the period when the rotating magnetic head 3a exists at the 40° portion in FIG.
A PCM audio signal is applied to the input terminal 7 shown in the figure and amplified by the recording amplifier 6. 2. Next, during the period when the rotating magnetic head 3a passes through the 40° portion and is present at the 180° portion in FIG. 1, a video signal is applied to the input terminal 7 and passes through the same path as described above. This leads to the magnetic tape 2. The same thing can be said about the rotating magnetic head 3b, and the PCM audio signal and video signal are transferred to the magnetic tape 2 in a time-division manner by a timing signal via the input terminal 11, the recording amplifier 10, the switch 5b, the transformer 4b, and the rotating magnetic head 3b. reach. An example of a recording pattern recorded on the magnetic tape 2 in this manner is shown in FIG. In the figure,
a, b, a, b... are tracks recorded by the rotating magnetic heads 3a, 3b, and the track area where the PCM audio signal P is recorded corresponds to the 40° portion in Fig. 1, and the video signal The track area where V is recorded corresponds to the 180° portion of FIG.

Next, during reproduction, the rotation of the head drum 1 is controlled by a servo circuit (not shown) so that it rotates at approximately the same speed as during recording, and the rotating magnetic heads 3a,
A tracking servo (not shown) performs tape running control so that magnetic tape 3b correctly scans the tracks on the running magnetic tape 2, and the rotating magnetic heads 3a and 3b record from tracks a and b in response to a timing signal. play the signal being played. The signal reproduced from the track a by the rotating magnetic head 3a is transferred to the transformer 4a and switch 5 shown in FIG.
a, reaches the terminal 9 via the reproduction amplifier 8. Similarly, the signal reproduced by the rotating magnetic head 3b from the track b reaches the terminal 13 via the transformer 4b, the switch 5b, and the reproduction amplifier 12. The envelope of the reproduced signal thus reproduced is shown in FIGS. 4A and 4B. Both of these signals include video signals and
Since the PCM audio signal is included in a time-division manner, both of these signals are applied to the changeover switch 14 shown in FIG.
Sorts audio signals. That is, Fig. 4C
is a signal schematically expressed as the video signal extraction timing, and is a signal schematically expressed as the video signal extraction timing, and
A is alternately switched so that only the video signal led out to the terminal 9 or the terminal 13, that is, the video signal V shown in FIGS. 4A and 4B, is led to the output terminal 15. As a result, a continuous video signal is extracted as shown in FIG. 4E. On the other hand, FIG. 4D is a signal schematically represented as the PCM audio signal extraction timing, which is led out to terminal 9 or terminal 13 by alternately switching switch 14b in changeover switch 14.
Only the PCM audio signal, ie, the PCM audio signal P shown in FIGS. 4A and 4B, is led to the output terminal 16.
As a result, only the PCM audio signal is extracted as shown in FIG. 4F. The video signal and PCM audio signal thus obtained are returned to their original signals by a video signal demodulation circuit and a PCM audio signal demodulation circuit (not shown in FIG. 2), respectively.

The above is a description of the normal recording and playback operations. Next, the after-recording operation of audio signals will be explained. After-recording usually involves re-recording only the PCM audio signal from a desired point while visually observing the playback screen. To explain this using FIG. 4, in FIGS. 4A and 4B, the 180° portion is in the reproduction state, and the 40° portion is where a new PCM audio signal is being recorded. Overwriting the new PCM audio signal on top of the original recorded PCM audio signal, i.e.
By overwriting, the originally recorded PCM audio signal is erased and a new PCM audio signal can be recorded, which is utilized for performing after-recording. During after-recording, the operation of the video signal in FIG. 2 is exactly the same as that during playback described above. On the other hand, for PCM audio signals, the rotating magnetic head 3a or 3b shown in FIG.
While in the 40° portion, a PCM audio signal is applied to the recording amplifier 6 or 10 and recording is performed.
For example, when the rotating magnetic head 3a comes to the 40° position in FIG. 1, the switch 5a in FIG. 2 is switched to the recording side by the timing signal shown in FIG. 4D.
A PCM audio signal is applied to the rotating magnetic head 3a.

Now, when performing after-recording with a conventional magnetic recording and reproducing device, it is necessary to reproduce the video signal with one rotating magnetic head and simultaneously record the PCM audio signal with the other rotating magnetic head.
During this time, it was necessary to avoid crosstalk interference from the recording system to the reproduction system, and in particular, strict shielding was required for the rotary transformer. For example, the reproduction output of a rotating magnetic head is several microvolts,
On the other hand, since the voltage applied to the rotating magnetic head for recording is several 100 mV, it is necessary to keep the crossstroke below 80 dB in order to prevent the after-recording PCM audio signal from leaking to the playback video signal side. Additionally, when crosstalk enters the playback video signal, beat disturbances occur, making the playback screen on the TV unsightly. Furthermore, if the crosstalk was large, the playback amplifier would become saturated in the portion corresponding to 40°, resulting in the disadvantage that the playback image may not be reproduced.

[Summary of the Invention] This invention has been made in order to eliminate the drawbacks of the conventional ones as described above, and therefore, the main object of the invention is to provide first and second parallel tracks on one parallel inclined track. When a first information signal is after-recorded on a magnetic tape on which an information signal has been recorded, the first information signal is recorded while avoiding crosstalk interference from the first information signal to be after-recorded to the second information signal to be reproduced. An object of the present invention is to provide a magnetic recording/reproducing device capable of after-recording.

To summarize the present invention, in a magnetic recording and reproducing apparatus that records and reproduces first and second information signals on parallel inclined tracks on a magnetic tape using a first or second rotating magnetic head, at least one new information signal is provided. a second information signal to be reproduced from the parallel tilt track by the first or second rotary magnetic head; When the first information signal is reproduced by the head and stored in the storage means, and after-recorded on the front or rear end of the parallel inclined track by the first or second rotating magnetic head, at least during the after-recording period, The present invention is a magnetic recording/reproducing apparatus which reads out a second information signal stored in a storage means and replaces the second information signal reproduced by the first or second rotating magnetic head with the second information signal.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, in the description of this embodiment, the first to
Descriptions of parts that overlap with the description of FIG. 4 will be omitted as appropriate.

FIG. 5 is a diagram showing the relationship among a head drum, a rotating magnetic head, and a magnetic tape in a magnetic recording/reproducing apparatus according to an embodiment of the present invention. In the figure, new rotating magnetic heads 20a and 20 are added to the head drum 1.
b, which are provided on the head drum 1 with an angular spacing of 180° from each other. Also,
The rotating magnetic head 20a is provided in advance of the rotating magnetic head 3a by an angular distance of θ°. Here, it is assumed that θ°≧40°. Further, a rotating magnetic head 20a,
20b is provided with an appropriate step difference relative to the rotating magnetic heads 3a, 3b so that the rotating magnetic heads 3a, 3b can correctly scan the tracks scanned. For example, if the widths of the rotating magnetic heads are the same, the recording pattern on the magnetic tape 2 shown in FIG.
0b to the rotating magnetic heads 3a, 3b (θ°/
It is sufficient to add a step upward by 180°) x (track pitch).

FIG. 6 is a block diagram of a magnetic recording/reproducing apparatus which is an embodiment of the present invention. The block diagram of FIG. 6 differs from the block diagram of FIG. 2 in the following points. That is, the rotating magnetic head 20a is newly installed.
is connected to the changeover switch 21 via the transformer 4c, and the rotating magnetic head 20b is connected to the changeover switch 21 via the transformer 4b. The changeover switch 21 connects the playback amplifier 22 and the video signal demodulation circuit 2.
3. Connected to the changeover switch 26 via the memory circuit 24. Additionally, the timing signal generation circuit 31
0 is connected to changeover switch 21 and changeover switch 26. A timing signal from timing signal generation circuit 310 is applied to changeover switch 21 and changeover switch 26 to control switching of these switches. Further, the output terminal 15 is connected to a changeover switch 26 via a video signal demodulation circuit 25. The changeover switch 26 is connected to the output terminal 27.

Next, the operation of this magnetic recording/reproducing device will be explained. In Figure 6, normal recording/playback is as follows:
The operation is similar to that described in connection with FIG. Therefore, here, the after-recording in this magnetic recording/reproducing apparatus will be explained below. In the playback state, as described above, when the rotation of the head drum 1 is controlled and the tape running is controlled by the tracking servo, the playback video signal and the playback PCM are output to the output terminals 15 and 16 in FIG. A signal is output at a predetermined timing. The situation at this time is exactly the same as that shown in FIGS. 4A to 4F. At this time, since the rotating magnetic heads 20a and 20b are provided as described above, the rotating magnetic heads 3a and 3b
It is now possible to play back the video signal that has been recorded from the track in advance. Here, the fifth
Since the angular interval θ° shown in the figure is set larger than 40°, when the rotating magnetic head 3b reaches the 40° part in FIG. track a
Scanning of the track area where the video signal (see FIG. 3) is recorded has been completed. Similarly, when the rotating magnetic head 3a reaches the 40 DEG section in FIG. 5, the rotating magnetic head 20b has finished scanning track b. Therefore, the rotating magnetic head 20a is rotated at an angle of 40 degrees as shown in FIG.
When scanning a track at a 40° angle symmetrical to the center point, the reproduction signal from the rotating magnetic head 20a is guided to the reproduction amplifier 22 via the transformer 4c and the changeover switch 21 shown in FIG. The operating timing of the changeover switch 21 is expressed in terms of time as shown in FIG. 4G. The output of the reproduction amplifier 22 is applied to a video signal demodulation circuit 23 to be returned to the original video signal, and then applied to a memory circuit 24. The memory circuit 24 is composed of, for example, an A/D converter, a digital memory, and a D/A converter, and the period playback video signal shown in FIG. 4G is read and stored in the digital memory. Next, using the timing signal shown in FIG. 4D,
This stored video signal is just read out while the PCM audio signal is present, and when this reading is done, the memory of the memory circuit 24 is cleared. Similarly, when the rotating magnetic head 20b is located at a 40° portion symmetrical to the center point, the sixth
Through the transformer 4d in the figure and the changeover switch 21,
The reproduction signal of the track next to the track already scanned by the rotating magnetic head 20a is transmitted to the rotating magnetic head 20b.
The stored video signal is then read out and the memory of the memory circuit 24 is cleared. Hereinafter, such an operation is performed by the rotating magnetic heads 20a, 20.
This is done alternately for b. Assuming that after-recording is currently being performed, input terminals 7 or 11 in FIG.
A PCM audio signal is applied and the fourth
During the period shown in Figure D, the PCM audio signal is in a recording state. At this time, due to the above-mentioned crosstalk interference, even if the video signal derived from the output terminal 15 is passed through the video signal demodulation circuit 15, the video signal is disturbed during the above period, as shown in FIG. 7A, for example. Put it away. Therefore, during this period, the stored signal is read from the signal memory circuit 24 and replaced with this disturbed video signal. That is,
Output of video signal demodulation circuit 25 and memory circuit 24
The video signal of the video signal demodulation circuit 25 is outputted to the output terminal 27 except during the after-recording period of the PCM audio signal, and when the after-recording period of the PCM audio signal arrives, the output of the switch 26 is guided to the changeover switch 26. for example,
Switching control is performed using the timing signal shown in FIG. 4D, and the video signal of the memory circuit 24 is guided to the output terminal 27 to obtain a continuous video signal output.
As is clear from the above, the memory circuit 24 has the seventh memory at the timing shown in FIG. 7B.
The video signal on the track corresponding to the after-recording period in Figure A is stored, and since no crosstalk interference due to after-recording occurs at this timing, a normal playback signal without interference is stored. . Next, this stored video signal is synchronized with the horizontal synchronization signal of FIG. 7A by using the timing signal shown in FIG. 4D, the horizontal synchronization signal of FIG. 7A, etc. It is read out during the after-recording period on the same time base as the playback video signal.

As described above, a reproduced video signal that is not interfered with by crosstalk due to after-recording can be obtained at the output terminal 27, so that when this signal is displayed on a television, a good reproduced screen can be obtained.

In the above embodiment, two new rotating magnetic heads are added to the head drum, but it is also possible to add one rotating magnetic head. That is, in the case of television signals, since the images are very similar between adjacent fields, the video signals stored in the memory circuit 24 are divided into two.
There is no problem in practical use even if it is used during the field after-record period. In this case, instead of clearing the read video signal immediately as described above, it is sufficient to read it twice using the timing signal shown in FIG. 4D, then clear it, and read every two fields.

Further, as the rotating magnetic head added in the above two embodiments, a magnetic head dedicated to special reproduction such as slow still, which has been commonly used in the past, may be used.

The rotating magnetic head added in the first embodiment is one in which the speed of the magnetic tape can be switched between two types, and a dedicated rotating magnetic head corresponding to each magnetic tape speed is used. Either dedicated rotating magnetic head may be used.

In addition, in the first embodiment, when recording and reproducing an FM audio signal superimposed on a video signal, an audio signal without interference can be obtained by adding a memory circuit to the reproduced audio signal as well. Needless to say.

Further, in the above embodiment, a system was described in which a PCM audio signal was recorded at the front end of the truck, and a video signal was recorded thereafter, but the present invention can be easily applied even if the relationship between these fronts and rears is reversed. Applicable.

[Effects of the Invention] As described above, according to the present invention, magnetic recording/reproduction is performed in which first and second information signals are recorded and reproduced on parallel inclined tracks on a magnetic tape by the first or second rotating magnetic head. In the apparatus, at least one other rotating magnetic head and a storage means are newly added, and the second information signal reproduced from the parallel inclined track by the first or second rotating magnetic head is reproduced prior to the reproduction. when the first information signal is reproduced by at least one other rotating magnetic head and stored in the storage means, and after-recording the first information signal at the front or rear end of the parallel inclined track by the first or second rotating magnetic head; At least during the after-recording period, the second information signal reproduced by the first or second rotating magnetic head is replaced by the second information signal stored in the storage means. Therefore, crosstalk interference from the first information signal to be after-recorded to the second information signal to be reproduced is avoided.
The first information signal can be after-recorded.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship among a head drum, a rotating magnetic head, and a magnetic tape in a conventional magnetic recording and reproducing apparatus that records and reproduces video signals and PCM audio signals in a time-division manner. FIG. 2 is a block diagram of the main parts of a recording/reproducing transmission system in a conventional magnetic recording/reproducing apparatus. FIG. 3 is a diagram showing a recording pattern on a magnetic tape recorded by a conventional magnetic recording/reproducing device. FIG. 4 is a diagram for explaining recording and reproducing operations of video signals and PCM audio signals in a conventional magnetic recording and reproducing apparatus and a magnetic recording and reproducing apparatus that is an embodiment of the present invention. FIG. 5 is a diagram showing the relationship among a head drum, a rotating magnetic head, and a magnetic tape in a magnetic recording/reproducing apparatus according to an embodiment of the present invention. FIG. 6 is a block diagram of a magnetic recording/reproducing apparatus which is an embodiment of the present invention. FIG. 7 is a waveform diagram of a reproduced video signal for explaining after-recording in a magnetic recording/reproducing apparatus according to an embodiment of the present invention. In the figure, 1 is a head drum, 2 is a magnetic tape, 3a, 3b, 20a, 20b are rotating magnetic heads, 4, 40 are rotary transformers, 5, 14, 2
1 and 26 are changeover switches, 6 and 10 are recording amplifiers, 8, 12, and 22 are playback amplifiers, 23 and 25 are video signal demodulation circuits, 24 are memory circuits, and 30
A and 30b are rotation detectors, and 31 and 310 are timing signal generation circuits. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A plurality of rotating magnetic heads are provided on the head drum at predetermined angular intervals, and the plurality of rotating magnetic heads are sequentially brought into contact with the magnetic tape to maintain the predetermined angular intervals. Parallel inclined tracks longer than corresponding track lengths are sequentially formed on the magnetic tape, and in the adjacent preceding parallel inclined track and the subsequent parallel inclined track, one of the plurality of rotating magnetic heads is connected to the preceding parallel inclined track. When making contact with the rear end of the parallel inclined track, another of the plurality of rotating magnetic heads simultaneously contacts the front end of the following parallel inclined track, and the plurality of rotating magnetic heads , a first information signal is recorded on a front end or a rear end of the parallel inclined track, and a second information signal is recorded on a portion of the parallel inclined track other than the front end or a portion other than the rear end. a magnetic recording device configured to record, reproduce the first and second information signals from the parallel tilted tracks by the plurality of rotating magnetic heads, and demodulate the reproduced first and second information signals. In the reproducing apparatus, the second information signal is provided on the head drum in advance of the plurality of rotating magnetic heads at a desired angular interval, and is configured to selectively reproduce the second information signal from the parallel inclined track by the plurality of rotating magnetic heads. at least one other rotating magnetic head that reproduces at a predetermined timing prior to reproduction; and the second rotating magnetic head that reproduces with the other rotating magnetic head.
demodulating means for demodulating the first information signal; storage means for storing the output of the demodulating means; after-recording the first information signal on the rear or rear end of the parallel inclined track by the plurality of rotating magnetic heads; At least during the after-recording period,
the second magnetic head reproduced by the plurality of rotating magnetic heads;
1. A magnetic recording and reproducing apparatus, comprising: a switching means for replacing the information signal with the second information signal stored in the storage means at a predetermined timing. 2. The plurality of rotating magnetic heads are composed of first and second rotating magnetic heads, and the at least one other rotating magnetic head is arranged on the head drum with respect to the plurality of rotating magnetic heads. 2. The magnetic recording and reproducing apparatus according to claim 1, wherein the magnetic recording and reproducing apparatus is provided in advance by an angular interval larger than an angular interval corresponding to a track area in which one information signal is recorded. 3. The at least one other rotating magnetic head comprises a third and a fourth rotating magnetic head, and the third rotating magnetic head receives the second information signal reproduced by the first rotating magnetic head. The fourth rotary magnetic head is configured to reproduce the second information signal reproduced by the second rotary magnetic head prior to the reproduction. 2. The magnetic recording and reproducing device according to item 2. 4. The at least one other rotating magnetic head has a step on the head drum with respect to the first or second rotating magnetic head, and the step is between the at least one other rotating magnetic head and the immediately preceding one. 4. The magnetic recording and reproducing apparatus according to claim 2, wherein the angular distance θ° with respect to the first or second rotating magnetic head is (θ°/180°)×(track pitch). 5. Claim 2 or 3 or 5, wherein the rotating magnetic head is a normal recording/reproducing rotating magnetic head, and the at least one other rotating magnetic head is a special reproduction rotating magnetic head. 4. The magnetic recording and reproducing device according to item 4. 6. A dedicated rotary magnetic head capable of switching between two types of magnetic tape speeds and corresponding to each of the magnetic tape speeds, the first and second
The rotating magnetic head is a dedicated rotating magnetic head compatible with a first magnetic tape speed, and the third and fourth rotating magnetic heads are
5. A magnetic recording and reproducing apparatus according to claim 3, wherein said rotating magnetic head is a dedicated rotating magnetic head compatible with a second magnetic tape speed, or vice versa.