JPH02155380A - Video signal recorder - Google Patents

Abstract

PURPOSE:To prevent disturbance of a reproduced picture by allowing other recording head to record a control signal for a period except a period when one recording head records an audio signal and a period when an erasure head erases the audio signal. CONSTITUTION:A switch circuit SW6 is provided to select a replacement signal in place of a disturbed reproducing signal at after recording of an audio signal. That is, the switch circuit SW6 selects an input terminal (g) for a period when a recording current is fed to a head and for a period when an erasure current is fed to an erasure head, and the switch circuit SW6 selects an input terminal (f) for the period except the periods above. The switch circuits SW6, SW7 are synchronized, and when the switch circuit SW6 selects the input terminal (f), the switch circuit SW7 is closed, while the switch circuit SW6 selects the input terminal (g), the switch circuit SW7 is opened. Thus, an AFC circuit 18 generates a signal of a horizontal frequency synchronized with the horizontal synchronizing signal of a reproduced signal without disturbance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video signal recording device that can be used to record a compressed color video signal obtained by band-compressing a high-definition signal.

[Summary of the invention]

The present invention provides a video signal recording device that records a video signal and an audio signal in separate recording areas, in which the recording position of the control signal necessary to reproduce the entire image of one field or one frame is located at the recording position of the audio signal. By avoiding overlapping with the recording operation period or erasing operation period for post-recording, it is possible to prevent the reproduced image from being disturbed when performing the post-recording of the audio signal while viewing the reproduced image.

[Conventional technology]

2. Description of the Related Art A VTR is known that records a time-base compressed PCM audio signal in a dedicated recording area when recording a video signal on a magnetic tape using a rotating head. FIG. 5 shows an example of this type of VTR, in which a pair of recording and reproducing heads HA and HB are provided 180° opposite each other on a drum that rotates in the direction of arrow χD at a frame frequency indicated by DR.

With the magnetic tape T wound around the circumferential surface of the drum DR at a winding angle of 180° or more, move the arrow XT at a predetermined speed.
It runs in the direction of force. A video signal is recorded in the range of the wrapping angle θv (=180°), and a time-axis compressed PCM audio signal is recorded in the range of the wrapping angle θa (for example, about 41°) where the scanning of the two heads overlaps. be done.

Reproduction signals SA and SB of heads HA and HB of a VTR having the head arrangement shown in FIG. 5 are obtained at the timing shown in FIG. 6, respectively. In such a VTR, when dubbing an audio signal while viewing a playback image, the leakage magnetic flux of the recording signal supplied to one head at the winding angle θa is picked up by the other head, and a normal playback signal is output from the other head. cannot be obtained, and the reproduced image is distorted. Conventionally, the reproduced video signal during post-recording is replaced with a separately formed video signal, such as a gray level signal.

[Problem to be solved by the invention]

When recording an NTSC color video signal, there is no problem with replacing it with another signal. However, in the case of a video signal where the control code necessary for image reproduction is inserted for each field or frame. As an example of a video signal containing a control code, if this control code cannot be reproduced during post-recording of an audio signal, the entire image of one field or frame cannot be reproduced.
2. Description of the Related Art A method for compressing and transmitting a wideband high-visibility signal, such as that described in Japanese Patent No. 994, is known. This transmission method is MUSE (mul-tiple
5ub-Nyquist sampling enco
ding), which combines the time-domain compression multiplexing (TCI) transmission method, which compresses and multiplexes the luminance signal and chrominance signal in the time-domain, and offset sampling, which shifts the phase of subsampling at a four-field period. It is a compression method.

The MUSE signal is allocated to signals within one frame as shown in FIG.

The MUSE signal transmits the value of the sampled signal, and one line consists of 480 samples, and a frame (1) consists of 1125 lines. A positive horizontal synchronizing signal is assigned to 12 samples of one line, 94 samples are assigned to a color signal, and 374 samples are assigned to a luminance signal. A VIT signal and a frame pulse are inserted at the beginning of one frame. The VIT signal is a reference signal for equalizing the transmission path. The audio signal is time-base compressed and inserted into the vertical blanking period.

A control signal is inserted between the 12th sample and the 106th sample in the 559th line to the 563rd line of one frame. The capacity of the control signal is 32 bits per field. Bit numbers 1 to 32 are assigned to these 32 bits.

The contents of the control signal include the subsampling phase of the luminance signal, the subsampling phase of the color signal, presence or absence of emphasis, motion information, and the like. For example, bit number 1
6.17.18, motion information is inserted. In other words, the meanings of these three bits as O51.2.3.4 to 7 are determined, with 0 meaning normal (with movement), 1 meaning a completely still image, and 2. indicates a quasi-stationary side, 3 indicates a scene change, and 4 to 7 indicate the degree of movement. This motion information is used to control signal processing on the encoder side.

When the above-mentioned MUSE signal is alternately recorded field by field on tape T by heads HA and HB, the control code is reproduced in the latter half of the video signal period, as shown by diagonal lines in FIG. . However, during this period, as mentioned above, during post-recording of the audio signal,
This is a period during which correct reproduction cannot be performed, and therefore, during post-recording, there is a problem that the entire screen of the reproduced image is disturbed.

In order to solve the problem during dubbing, it is conceivable to incorporate a playback amplifier into the drum DR and amplify the level of the playback signal near the head. However, this method is undesirable because it has the drawback of increasing costs due to the increase in the number of amplifiers and the supply of power to the amplifiers.

Furthermore, as shown in FIG. 8, even in a VTR in which a rotary erasing head E is provided on the drum DR, during post-recording of audio signals, the erasing signal is supplied to the erasing head in addition to the recording signal period. , since the reproduced signal is disturbed, there is a problem that the reproduced image is disturbed for the same reason as mentioned above.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a video signal recording apparatus that eliminates the problem of distorted reproduced images due to the inability to reproduce control codes during post-recording of audio signals.

[Means to solve the problem]

The invention described in claim (1) provides: (1) an apparatus for recording a video signal into which a control signal necessary for decoding a video signal (for example, a MUSE signal) of a period such as a field or l frame is inserted; A drum DR is provided with recording heads HA and HB, which are rotated at a predetermined number of rotations, and are run while being wound around the circumferential surface of the drum DR. The tapes T are respectively recorded during different periods in one scan, and during the period excluding the period when the recording heads HA and HB record audio signals, the recording heads HA and HB record audio signals. The invention according to claim (2), wherein the head is characterized by a control signal, is an apparatus for recording a video signal into which a control signal necessary for decoding a video signal of a period such as one field or one frame is inserted. A recording head EA, EB and two or more recording heads HA, HB are provided, a drum DR rotates at a predetermined number of rotations, and a drum DR that runs while being wound around the circumferential surface of the drum DR to record video signals. and an audio signal are respectively recorded at different periods in one scan of the recording head, and the tape T is provided with a tape T on which the audio signals are recorded at different periods during one scanning of the recording head, and the period during which one of the recording heads records the audio signal and the period for this recording. Then, the other recording heads record the control signal within a period excluding the period in which the erasing heads EA and EB erase the audio signal.

[Effect]

Since the audio signal recording area is rewritten during audio signal dubbing, the recording signal is supplied during the period when the heads HA and HB scan the audio signal recording area. In a period that overlaps with this period, the video signal cannot be reproduced correctly. Furthermore, when a rotating erasing head is used, the video signal cannot be correctly reproduced not only during the recording signal period but also during the period when the erasing current is supplied to the erasing heads EA and EB.

In this invention, a control signal such as a control code of a MUSE signal is not included during a period in which these video signals cannot be reproduced correctly. Therefore, it is possible to post-record the audio signal while viewing the reproduced image.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the circuit configuration of this embodiment, and FIG. 2 shows the head arrangement of this embodiment.

In FIG. 2, DR indicates a drum rotating in the direction of the force arrow XD at the frame frequency. This drum DR has 18
A pair of recording and reproducing heads HA and HB and 18 facing each other
A pair of erasing heads EA and EB are provided facing each other at 0°. With the magnetic tape T wound around the circumferential surface of the drum DR at a winding angle of 180° or more, the magnetic tape T is moved at a predetermined speed in the direction of the force indicated by the arrow XT at a zero winding angle θv (-18
The MUSE signal is recorded in the range of 0°), and the time-axis compressed PCM audio signal is recorded in the range of the wrap angle θa (for example, about 41°) where the scans of the two heads overlap. The erasing heads EA and EB are provided at positions ahead of the recording/reproducing heads HA and HB by an angle of θC, respectively. During recording, the erasing head EA
The erase head EB erases the track formed by the head HA, and the erase head EB erases the track formed by the head HB.

FIG. 3 shows a tape pattern formed by a VTR having the head arrangement described above.
Tracks are alternately formed by the heads HA and HB, each consisting of a recording area where a MUSE signal for one field corresponding to V is recorded and a recording area where a PCM audio signal corresponding to the winding angle θa is recorded. Ru. An AV guard is provided between the MUSE signal recording area and the PCM audio signal recording area.

In FIG. 1, a MUSE signal is supplied to an input terminal indicated by 1. The MUSE signal is supplied to the FM modulation circuit 3 after being subjected to pre-emphasis processing necessary for recording, addition of a negative polarity synchronization signal and a burst signal, etc. in the signal processing circuit 2 . The output signal of the FM modulation circuit 3 is supplied via the equalizer circuit 4 to the input terminals C of the switch circuits SWI and SW2, respectively. Switch circuit SWI and S
W2 is provided for switching recording signals,
Input terminals C and P selected during the recording period of the MUSE signal
Input terminal d selected during the recording period of the CM audio signal
and an input terminal e that is selected during a period in which no recording operation is performed.

The recording signal from the switch circuit SWl is sent to the recording/reproducing head H via the recording amplifier 5, the recording side terminal r of the recording/reproducing switch SW3, and a rotary transformer (not shown).
A is supplied. Similarly, the recording signal from the switch circuit SW2 is supplied to the recording/reproducing head HB via the recording amplifier 6, the recording side terminal r of the recording/reproducing switch SW4, and a rotary transformer (not shown).

The audio signal from the input terminal 7 is converted into a PCM audio signal by the A/D converter 8 and supplied to the digital signal processing circuit 9. This audio signal corresponds to the MUSE signal for one field period to be recorded. The digital signal processing circuit 9 performs processing such as time axis compression and error correction code encoding. The output signal of the digital signal processing circuit 9 is supplied to the input terminal d of each of the switch circuits SWI and SW2 via the equalizer circuit 10. The switch circuits SW1 and SW2 select the input terminal d within the range of the winding angle θa, and the PCM audio signal is recorded in the audio signal recording area of the tape T.

The reproduction signal from the head HA is supplied to the input terminal a of the switch circuit SW5 via a rotary transformer (not shown), the reproduction side terminal p of the switch SW3, and the reproduction amplifier 11. Similarly, the reproduction signal of the head f (B) is supplied to the input terminal of the switch circuit SW5 via a rotary transformer (not shown), the reproduction side terminal p of the switch SW4, and the reproduction amplifier 12. , the head HA has a wrapping angle θV
When reproducing a signal from the tape in the range of .theta.V, input terminal a is selected.Next, when the head HB reproduces a signal from the tape within the range of the winding angle .theta.V, input terminal A is selected.

Therefore, a continuous reproduced MUSE signal is obtained from the switch circuit SW5.

Other switch circuits, which are omitted in FIG. 1 for simplicity, extract the PCM audio signals reproduced during the period in which the heads HA and HB scan the tape T within the range of the winding angle θa.

The reproduced PCM audio signal is converted back into an analog audio signal after being subjected to processing such as time axis expansion and error correction.

The reproduced signal from the switch circuit SW5 is sent to the equalizer circuit 1.
3 to the FM demodulation circuit 14 through F Ml!
Pi circuit 14 Color (7) reproduction MUSE signal is supplied to signal processing circuit 15 and synchronization separation circuit 16. The signal processing circuit 15 performs processing such as removal of negative polarity synchronization signals and burst signals added during recording, and de-emphasis. The MUSE signal from the signal processing circuit 15 is supplied to the input terminal f of the switch circuit SW6. A reproduced MUSE signal is taken out from the switch circuit SW6 to the output terminal 17.

The horizontal synchronization signal separated by the synchronization separation circuit 16 is supplied to the AFC circuit 18 via the switch circuit SW7.

The AFC circuit 18 generates a horizontal frequency signal synchronized with the separated horizontal synchronizing signal, and this horizontal frequency signal is supplied to the replacement signal generating circuit 19. The replacement signal generation circuit 19 has a signal form similar to that of the MUSE signal,
For example, a replacement signal corresponding to a gray image is generated.

This replacement signal is supplied to the input terminal g of the switch circuit SW6.

The switch circuit SW6 is provided to select a replacement signal in place of the distorted reproduction signal when dubbing the audio signal. That is, during the period in which the recording current is supplied to the head and the period in which the erasing current is supplied to the erasing head, the switch circuit SW6 selects the input terminal g, and outside these periods, the switch circuit SW6 selects the input terminal f. do. The switch circuits SW6 and SW7 are synchronized, and during the period when the switch circuit SW6 selects one input terminal f, the switch circuit SW7 is turned on and during the period when the switch circuit SW6 selects the other input terminal g. Then, the switch circuit SW7 is turned off.

Therefore, the AFC circuit 18 generates a signal with a horizontal frequency synchronized with the horizontal synchronizing signal of the reproduced signal without disturbance.

20 indicates an oscillator for generating an erase signal. The erasure signal is
It is supplied to one input terminal r of switch circuits SW8 and SW9, respectively. The other input terminal q of the switch circuits SW8 and SW9 is grounded. switch circuit S
Erasing current is supplied to the erasing heads EA and EB via the terminal r sides of W8 and SW9 and amplifiers 21 and 22, respectively. The input terminals r of the switch circuits SW8 and SW9 are selected at the timing of track erasing prior to the recording operation.

The above-mentioned switch circuits SWI, SW2, SW5, SW6,
SW7, SW8, and SW9 are each controlled by a switching signal (not shown) synchronized with the rotation of the drum DR. The switching signal can be formed from a signal obtained by magnetically detecting the rotation of the drum DR, for example.

In the embodiment of the present invention described above, the operation when dubbing an audio signal will be described with reference to FIG.

FIG. 4A shows the rotational phases of the reproduction signal SA of the recording/reproducing head HA, the reproduction signal SB of the recording/reproducing head HB, and the erasing heads EA and EB. On the other hand, Herad H
By scanning the tape T in the range of the winding angle θV, that is, the recording area of the video signal, the reproduction output of the MUSE signal is obtained, and the head HB is in the range of the winding angle θa,
That is, by scanning the tape T in the recording area of the PCM audio signal, a reproduced output of the PCM audio signal can be obtained. Similarly, the reproduced signal SB is obtained from the other Herad HB. As shown in the fourth diagram, the switch circuit SW5 selects the input terminal a during the period when the head HA scans the video signal recording area, and selects the input terminal a during the period when the head HB scans the video signal recording area. A reproduced MUSE signal is obtained from the switch circuit SW5. The erasers EA and EB scan the tape T ahead of the heads HA and HB by an angle θC, respectively.

Figure 4B shows switch circuits SW1, SW3, SW2, S
The switch circuit SWI indicating the operation of W4 is connected to the head HA.
In the period in which the audio signal recording area is scanned, the input terminal d is selected, and the PCM audio signal to be dubbed is supplied to the recording amplifier 5 via the switch circuit SWI.

At the same timing as the switch circuit SWI, the switch circuit SW3 is connected to the recording side terminal r, and the head HA performs dubbing of the audio signal. During the period in which the head HB scans the audio signal recording area, the switch circuits SW2 and SW4 are controlled in the same way as described above, and the audio signal is post-recorded by the head HB.

The switch circuits SW8 and SW9 are controlled as shown in FIG.
An erase current is supplied to the erase heads EA and EB.

The switch circuit SW6 operates at the timing shown in FIG. 4B.
The input terminal g is selected during the period in which the PCM audio signal is recorded and the period in which the erasing current is generated at the timing shown in FIG. 4C, and the replacement signal is taken out as the video output. In addition, during periods other than the above-mentioned period, the input terminal f
is selected by switch circuit SW6, and the reproduced MUSE signal is output.

In the reproduced signals SA and SB of FIG. 4A, as shown with diagonal lines, the period during which the control code necessary for image reproduction is recorded is when the switch circuit SW6 is connected to the input terminal r.
is included in the selection period, and therefore a control code is obtained as the playback output. The MUSE signal is decoded using this control code.

In the embodiment described above, a pair of erasing heads EA and EB are provided, but the present invention can also be applied to a VTR configured to erase two tracks simultaneously with one erasing head. .

Further, the present invention can also be applied to a VTR that does not have a rotating erasing head but has a fixed erasing spatula r. In this case, the reproduced video signal is disturbed only during the period in which the recording current is generated. As can be seen from the timing chart of FIG. 4, by placing the audio signal recording area behind the video signal recording area, it is possible to prevent the area where the control code is recorded from being disturbed by the recording signal.

Furthermore, the present invention can also be applied to a VTR that compresses both a video signal and an audio signal and records the compressed video signal and audio signal within a wrap angle range of 180° or less. .

Furthermore, if the playback period of the control code overlaps with the recording period or erasing period of the audio signal due to restrictions such as the tape pattern or head arrangement, only the control code can be separated at the time of recording, and the control code can be recorded. The data may be recorded at a position that does not overlap with the period or the erasure period.

〔Effect of the invention〕

According to the present invention, since the control code can be correctly reproduced during post-recording of the audio signal, the image can be correctly restored from the reproduced signal, and the audio signal can be post-recorded while viewing the image.

Further, the present invention has the advantage that there is no need to incorporate a reproduction amplifier into the drum, and the cost does not increase.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
2 is a plan view showing the head arrangement in this embodiment, FIG. 3 is a route map showing the tape pattern, FIG. 4 is a timing chart used to explain the operation during dubbing in this embodiment of the invention, and FIG. 6 and 6 are a plan view and a timing chart used to explain an example of a conventional VTR, FIG. 7 is a route diagram used to explain a MUSE signal to which the present invention can be applied, and FIG. 8 is another example of a conventional VTR. FIG. 3 is a plan view showing the head arrangement of FIG. Explanation of main symbols in the drawings: DR Nidrum, HA, HB: Recording/playback head, EASEB: Erasing head, T: Tape, 1: MUSE signal input terminal, 7: Audio signal input terminal, : Playback MUSE signal output Terminal, : Replacement signal generation circuit, 20: Oscillator for generation of erase signal.

Claims (2)

[Claims] (1) In a device that records a video signal into which a control signal necessary for decoding a video signal of a period such as one field or one frame is inserted, two or more recording heads are provided and rotate at a predetermined number of rotations. and a tape that is run while being wound around the circumferential surface of the drum, and on which the video signal and the audio signal are respectively recorded in different periods within one scan of the head. , A video signal recording device characterized in that, within a period excluding a period in which one of the recording heads records the audio signal, another of the recording heads records the control signal. . (2) In an apparatus for recording a video signal into which a control signal necessary for decoding a video signal of a period such as one field or one frame is inserted, two or more recording heads and erasing heads are provided,
a drum rotated at a predetermined rotational speed; the drum is wound around the circumferential surface of the drum; the video signal and the audio signal are transmitted at different periods within one scan of the recording head; and a tape on which one of the recording heads records the audio signal and a period during which the erasing head erases the audio signal due to the recording. . A video signal recording device, characterized in that a head other than the recording head records the control signal.