JP2580583B2 - Recording and playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A. Industrial application fields B. Summary of the invention C. Conventional technology (FIGS. 4, 5, and 6) D. Problems to be solved by the invention E. Means to solve the problems F. Operation G. Embodiment G _1. Description of rotating head drum (FIGS. 1 and 2) G _2. Description of recording / reproducing circuit (FIG. 3) H. Effects of the invention A. Industrial application fields The present invention relates to a rotary head drum for rotating and scanning a magnetic tape in a video tape recorder (VTR) or the like,
In particular, the present invention relates to a recording / reproducing apparatus having a rotating head drum that enables simultaneous reproduction without the influence of crosstalk in a rotary transformer when a part of a track is post-recorded.

B. Summary of the Invention The present invention uses a rotary tape to rotate and scan a magnetic tape for use in a VTR or the like, divides one track into two areas, and records / reproduces information. In a recording / reproducing apparatus having a head drum, two heads for recording / reproducing, one head for reproducing, two heads for recording, and a flying erase for erasing an area necessary for post-recording When a head is provided and one area of the track is to be recorded later, the head arrangement is such that erasure and recording and reproduction of the other area do not overlap, and from the recording side in a rotary transformer connecting these heads and an amplifier circuit. By preventing the effect of crosstalk on the playback side, it is possible to perform playback simultaneously when post-recording a part of the track.

C. Conventional technology (FIGS. 4, 5, and 6) In an 8 mm VTR, an audio signal is frequency-modulated and mixed with a video signal in a state where it can be frequency-separated, so that an audio signal is recorded in a video area in one track. In addition to the case of recording, the audio signal or another audio signal is converted into PCM and
There is a method of recording in a PCM area which is divided into a video area and a region in a track. In this case the video area or
After recording one of the PCM areas (after recording,
Hereinafter, it is referred to as post-recording. ) To be done.

FIG. 4 shows a configuration of a conventional rotary head drum of an 8 mm VTR, and FIG. 5 shows a tape format thereof.

In FIG. 4, reference numerals 101 and 102 denote recording / reproducing heads which are arranged at an angle of 180 ° from each other and perform recording / reproducing of two tracks in one rotation. A flying erase head (FE) 103 is disposed at a position 90 ° ahead of the A-channel head 101, and simultaneously erases two tracks of an area necessary for performing post-recording. The magnetic tape (hereinafter abbreviated as “tape”) 104 has a rotating head drum 100 of about 221 mm or more.
, And one track is rotationally scanned within this 221 °. This one track has a PCM area of about 30 ゜ and 180
When the A channel head 101 starts rotating in the direction of the arrow and starts scanning the PCM area, the B channel head 102 scans the video area of the following track. 101 is PCM
When the scanning of the video area is started after the area scanning is completed, the B channel head 102 ends the scanning of the video area.

FIG. 5 shows the configuration of the tracks on the tape. The direction indicated by arrow A indicates the direction of movement of the head, the direction indicated by arrow B indicates the direction of movement of the tape. PCM area 105 and 1
A video area 106 for FM-modulating and recording a video signal and an audio signal of a field is divided into regions.

FIG. 6 is a timing chart showing an operation state of each conventional head when one area is post-recorded by the conventional rotary head drum. Post-recording includes a video insert performed on a video area and a PCM dubbing performed on a PCM area.

The figure (a) shows the case of video insertion, and the erase (erase) is 5 minutes from the PCM playback (PB) of the A channel head.
The recording is performed during the 180 ° rotation prior to the 4 ° rotation, and the video recording (REC) is started from the time when the rotation is made approximately 90 ° following the PCM reproduction by the A channel head. The PCM playback by the B channel head is started when the 234 ° angle is rotated from the start of the erase, and the video recording by the B channel head is started simultaneously with the end of the video recording by the A channel head after the 270 ° angle is rotated from the start of the erase. Then, the process ends with a rotation of 450 °. The above is repeated for a necessary period, and the video insertion is performed.

Fig. 6 (b) shows the case of PCM dubbing,
In FIG. 4, assuming that the time when the FE head finishes erasing the PCM area is 0 °, the erasing of the PCM area ends at approximately 0 ° ahead of the angle of approximately 36 °, and when the FE head rotates 54 °, the A channel is turned off. PCM recording by the head is performed by 90 ° rotation. Subsequently, video playback (PB) starts and ends with a 270 ° rotation. The PCM recording by the B channel head is performed 36 ° before the 270 ° rotation, and the operation ends at the 270 ° rotation. At the same time, the video reproduction by the B channel head starts and ends at the 450 ° rotation. The above is repeated for the necessary period to perform PCM dubbing.

The above-described square head and amplifier circuit are generally connected via a rotary transformer disposed on a rotation axis. For this reason, crosstalk is likely to occur in the rotary transformer, and the applicant has previously disclosed in Japanese Patent Application Laid-Open No. 60-163279 that the signal frequency of the erasing current flowing through the flying erase head when erasing the PCM area is trapped in the video signal system. It was proposed to set the frequency (1.5 MHz) to eliminate the influence of crosstalk and prevent the deterioration of the reproduction quality of the video signal.

D. Problems to be Solved by the Invention However, the problem solved by the above-mentioned conventional technique is that the crosstalk to the video reproduction side due to the erase signal at the time of PCM after-recording indicated by an arrow (a) in FIG. Only
As shown by arrows in FIGS. 6 (a) and 6 (b),
The problem of crosstalk received on the PCM reproduction side from the erase signal and recording signal in the video area at the time of video insertion and crosstalk received on the video reproduction side from the recording signal in the PCM area during PCM post-recording cannot be solved. Therefore, there is a problem that PCM reproduction or partial reproduction of a video signal cannot be performed during the period affected by the crosstalk. recent years,
VTRs have become more versatile and require more advanced editing functions, and it is becoming necessary to be able to reproduce other areas during post-recording.

As a countermeasure against the above-mentioned crosstalk, it is conceivable to electromagnetically separate the rotary transformers. However, since the rotary transformers are disposed on one rotating shaft of the rotary head drum, the separation is difficult. There are various problems, such as an increase in the number of parts, an increase in the complexity of the drum manufacturing method, maintenance and management of the system, and a guarantee of characteristics.

The present invention has been made in view of the above problems,
An object of the present invention is to provide a recording / reproducing apparatus having a rotating head drum that can obtain a PCM reproduction signal without crosstalk during video insertion without separating a rotary transformer and that can obtain a video reproduction signal without crosstalk during PCM dubbing. I do.

E. Means for Solving the Problems In order to achieve the above object, the configuration of the recording / reproducing apparatus having the rotating head drum of the present invention is as follows: a magnetic tape is rotated and scanned, and one track is divided into a first area and a second area. In a rotating head drum which divides into areas and records and reproduces different types of information respectively, and performs recording and reproduction of two tracks in one rotation, the first and second areas used for recording and reproduction of the first area and the second area are used. Second 2
Heads, a third one head used for reproducing the second area when recording the first area, and a fourth and fifth two heads used for recording the second area A second area formed by the first and second heads, comprising: a head; and a flying erase head for erasing an area necessary for recording after one of the first area and the second area. The first and second heads are brought close to each other in a range where the reproducing machines come close to each other, and the recording / reproducing machine using the first and second heads and the recording of the first and second heads by the flying erase head are performed. In the recording / reproducing timing, the third area is set to a range in which the reproduction of the second area which overlaps with the recording of the first area is performed.
A rotary head in which the fourth and fifth heads are arranged in a range in which recording of the second area is performed without overlapping at times other than the timing of reproduction by the first and second heads. It has a drum.

That is, the present invention is characterized by having a rotary head drum having a head arrangement in which erasing and recording of one area and reproduction of the other area do not overlap when performing post-recording.

F. Operation The head arrangement described above does not arrange the first and second two heads for recording / reproducing each track at an angle of 180 °, but overwrites the second area reproduction by the heads. Basically, they are arranged close to the area where they do not overlap. The recording, reproduction and erasure of the first area are not overlapped with the recording, reproduction and erasure of the first area, and the recording, reproduction of the second area and the third, fourth and fifth heads are performed within the rotation angle having a margin. Done by

In the above, video reproduction by the first and second two heads overlaps. However, one field signal is digitized by AD conversion, temporarily stored in a memory, and read out at a timing necessary for recording or reproduction, and is read out.
This can be dealt with by converting and restoring to a continuous field signal.

G. Examples Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

G _1. Description of Rotating Head Drum (FIGS. 1 and 2) FIG. 1 shows a head arrangement of a rotating head drum showing an embodiment of the present invention, and FIG. , The figure (b) shows the deployment arrangement on the week surface. This embodiment shows an example applied to an 8 mm VTR.

XX ′ indicates a reference surface of a head mount of the rotary head drum, and the rotary head drum 1 of the present embodiment has a reference surface X
-Head width 40μm mounted 30μm higher than -X '
Flying erase (FE) head 2 and the FE head 2 and the reference plane XX '45 degrees ahead in the rotational direction.
A B-channel recording / reproducing (R / Pb) head 3 mounted 15 μm higher and having a head width of 20 μm, and a head width 20 μm mounted on the reference plane XX ′ 90 ° ahead of the FE head 2 in the rotation direction. A-channel recording / reproducing (R / Pa) head 4 and B-channel PCM with a head width of 20 μm which is mounted at a height of 135 ° higher than the FE head 2 in the rotation direction by 25 μm above the reference plane XX ′. (PCMPBb) At the same 135 ° leading position as the head 5, 55 μm from the reference plane XX ′
B channel PC with a head width of 20μm mounted low by m
A dedicated head for M recording (PCMRECb) 6 and a dedicated A-channel PCM recording head (PCMRECa) 7 with a head width of 20 μm mounted 70 μm lower than the recording surface XX ′ 180 ° ahead of the FE head 2 in the rotational direction. Is mounted.

Of the head widths in the above configuration, the head width of the FE head 2 is twice the track width of 20 μm because two tracks are erased (frame erasure) at the same time.
The other head width is 20 μm corresponding to one track width. With an 8 mm VTR, two fields of recording are performed with one 360 ° rotation of the rotating head drum. Since recording of one field is performed on one track, the head step of one track or one field is 20 μm. The mounting height of each head is a value set by a head step determined from a field difference determined by an operation order. For example, recording by the R / Pa head 4 is performed after erasing of the FE head 2 starts.
The 270 ° rotation is equivalent to 1.5 fields, so that the FE head 2 is advanced 1.5 fields ahead of the R / Pa head 4, that is, 1.5 × 20 μm = 30 μm higher by a head step. Mounted. Also R / Pb head 3
Traces the next field (one field) with a 45 ° angle (−0.25 field) delay from the R / Pa head 4, so the field difference is 1−0.25 = 0.75.
Mounted 0.75 × 20 μm = 15 μm higher. PC
The MRECb head 5 reproduces PCM 90 ° angle (0.5 field) ahead of the R / PB head, so that 0.5 × 20 μm = 10 μm
Only higher than the R / Pb head 3, that is, from the reference plane XX '.
It is mounted at a height of 15 μm + 10 μm = 25 μm.

The arrangement of the PCMRECa head 7 and the PCMRECb head 6 in the present embodiment is such that, after performing PCM playback with the R / Pa head 4 and the R / Pb head 3, editing (or processing) based on the playback content is performed. It is possible to dub. Therefore, a second flying erase (FE) head 2 'dedicated to the PCM area is provided. The second FE head 2 ′ is driven after the end of PCM reproduction by the R / Pa head 4 and the R / Pb head 3.
R / Pa head 4 to 90 to erase CM area
゜ Angular delay (-0.5 field), that is, 0.5 × 20 μm = 10 μm
Mount low. The head width of the FE head 2 'is 40 .mu.m for erasing two tracks. In this case, since the erase period overlaps with the video reproduction, a low frequency (for example, 1.5 MHz) trapped in the video reproduction process is used as the erase signal frequency to prevent crosstalk. Also PCM
Since recording usually takes 2.5 fields or more from PCM reproduction for PCM processing such as encoding of an audio signal and time compression, in the embodiment, only 3.5 field difference, that is, 3.5 × 20 μm = 70 μm head stage difference corresponds. It is mounted low from the playback head R / Pa, wR / Pb head.

If it is not necessary to perform PCM playback during PCM dubbing, the FE head 2 'is unnecessary, and FE2 may be shared for erasing, or the erasing during PCM dubbing may not overlap with video playback. For this purpose, the FE head 2 'may be arranged at the same angle as R / Pa.

FIG. 2A is a timing chart at the time of video insertion in this embodiment. The heads used at the time of video insertion are an FE head for erasing a frame in the video area during a 180 ° rotation, a PCMPBb head dedicated for B-channel PCM playback having a B-channel azimuth, and an A-channel having an A-channel azimuth for an A-channel. An R / Pa head that performs PCM reproduction and video recording, and an R / Pb head that has a B channel azimuth and performs B channel video recording. At this time, the PCMPBb head is placed 225 ° behind the FE head as a head for performing PCM playback, the R / Pa head is placed 270 °, the R / Pb head is placed at 315 °, and the entire area angle of one track is placed behind 221 °. However, when PCM playback of B channel is performed by the R / Pb head, it overlaps with video recording of A channel. Therefore, only PCM playback of B channel is 90 times faster than the R / Pb head.
さ せ In advance, erase area of FE head and A channel
Switch the head to use it during PCM playback.
Therefore, at the time of video insertion, first, the video area of channel A and channel B is erased by 180 ° angle rotation by the FE head, and then the PCMPBb head located 135 ° forward (225 ° rearward) from the FE head rotates by 225 ° angle. By this time, PCM reproduction of B channel is completed, then PCM reproduction of A channel is completed by R / Pa head by 270 ° rotation, and then video recording of A channel is started by the same head and 450 ° rotation. Do until. On the other hand, B channel video recording
The R / Pb head performs rotation from 315 ° to 495 °. As is apparent from the figure, the PCM reproduction does not receive timing crosstalk from any other head.

FIG. 2 (b) is a timing chart at the time of PCM post-recording. The head used for PCM dubbing is the R
/ Pa, R / Pb head, PCMRECa head for A-channel PCM recording with A-channel azimuth, and PCMRE for B-channel PCM recording with B-channel azimuth
Cb head. In this case, the R / Pa and R / Pb heads are used for PCM playback and video playback of the A channel and B channel, respectively, and the PCM recording signals from the PCMRECa and PCMRECb heads do not cause crosstalk in those playbacks. , PCM
The RECa and PCM RECb heads must be arranged at a scan angle of 221 ° or more behind one track from the R / Pb head and 36 ° ahead of the R / Pa head in the PCM area. Considering that it takes more time than the field, the PCMRECa head is 3.5 fields, P
The CMRECb head is arranged at a position delayed by 3.5 fields from the R / Pb head, that is, as shown in FIG.
In FIG. 2 (b), during PCM dubbing, first, the R / Pa head performs A-channel PCM reproduction and video reproduction, and then delays the rotation by 45 ° for B-channel PCM reproduction. Perform video playback. When the above playback is completed, the PCM is 270 mm behind the R / Pa head in terms of layout.
With the RECa head, PCM recording is performed in the PCM area of the channel A with a delay of 3.5 fields in terms of timing, and the PCM RECb head 45 ° behind the PCM of the channel B with a delay of 3.5 fields in terms of timing. PCM recording is made in the area. As is clear from the figure, PCMRECa, PCMREC
There is no crosstalk from each head of b. Although the erase in the PCM area (not shown) overlaps during the video reproduction as described above, the influence of the crosstalk on the video reproduction is eliminated by switching the known erasing signal frequency.

G _2. Description of recording / reproducing circuit (FIG. 3) FIG. 3 is a block diagram of an embodiment of the recording / reproducing circuit using the rotary head drum.

Reference numeral 1 denotes the aforementioned circuit head drum, and each of the heads 2 to 7,
2 'is connected to each circuit via a rotary transformer (not shown). First, the configuration of the video recording system will be described. Record (RE
C) The video input is amplified by the amplifier 11 and the switch S ₁
Switches the channel. The A-channel video signal is A / D converted and temporarily stored in the memory 12, read out at a required timing, D / A-converted, and a recording (REC) / reproduction (PB) switching switch S of the A-channel head.
_The data is input to the R / Pa head 4 via ₂ . B channel video input is REC / PB switch of B channel head
The data is input to the R / Pb head 3 via S ₃ and S ₄ . Here, the processing of the memory may be performed on the video input side of the REC amplifier 11. The switches S ₁ , S ₂ , S ₃ , S ₄ are controlled by the system control unit 13, the switches S ₂ , S ₃ are switched to the REC side, and the switch S ₄ is used for video insertion during video recording. The side is switched to the B 'side during PCM reproduction. At the time of video insertion, an erasing signal for the video area is input to the FE head 2 from the erasing signal oscillating unit 14 according to an instruction from the system control unit 13 for a necessary period shown in FIG.

Next, the configuration of the video reproduction system will be described. First, switches 2 and 3 are P
Switched to B side. The video signal of channel A reproduced by the R / Pa head 4 is reproduced via the switches S ₂ and S ₅ (P
B) It is amplified by the amplifier 15 and becomes a video output. The video signal reproduced by the R / Pb head 3 is AD-converted and stored in the memory 12.
The temporarily stored, simultaneously with the termination of the video signal of A channel, the read video output is DA converted is amplified by the PB amplifier 15 through S ₅ are continuous in the A channel. Switch S ₅ is a channel switching is controlled by the system control unit 13. Also in the above, the reproduction output from each head may be output as it is via the PB amplifier 15 without switching, and the continuous processing may be performed externally.

Next, the configuration of the PCM reproduction system will be described. PCM signal A channel is restored stretched audio signal by the first PCM decoding unit 16 is reproduced through a R / Pa head 4, is input to the L channel side of the mix amplifier 17 for example via a switch S ₇ , And amplified to be an L-channel PCM output. Mix PCM reproduction of B-channel in the case of a normal case and the PCM audio dubbing is performed via the R / Pb head 3, is decompressed and restored by the audio signal by the second PCM decoding unit 18, for example via a switch S ₆ Amplifier
17 R channel side input, amplified and R channel
PCM output. PCM reproduction of the B channel during video inserts as described above, performed Manzanillo PCMPBb head 5 by switching the switch S ₄ for avoiding crosstalk.

Finally, the configuration of the PCM recording system will be described. The audio signals of the L and R channels are input to the mix amplifier 17 as PCM inputs, and the output is
Compressed CM conversion and time, is further added the necessary code by the PCM index unit 20, is input to the head via a switch S _8. Here, in the case of PCM postrecording, it is connected to the switch S _9, the system control unit 13
Channel switching is performed in accordance with the instruction of.
Input to the Cb head 6. In the case of this post-recording, various editing can be performed by operating the switches S ₆ and S ₇ and the mixing operation of the mix amplifier 17. It may be recorded in the same manner as described above in the case of normal recording, since no cross-talk problems in normal full recording, A channel PC by switch S ₈
For M recording, the data may be input to the R / Pa head, and for B channel PCM recording, the data may be input to the R / Pb head for recording.

The above is one embodiment of the present invention, and the present invention is not limited to the embodiment. Various applications and embodiments can be taken in accordance with the gist of the present invention. For example, the arrangement of the heads can change the intervals and the head steps in a range along the gist thereof.

H. Effects of the Invention As is clear from the above description, the head arrangement of the rotary head drum in the recording / reproducing apparatus of the present invention allows the rotary transformer to be electromagnetically separated from the rotary transformer during video insertion and after PCM after recording. During recording, the effects of erasing (erasing) and crosstalk from recording to reproduction are eliminated, and the other area without post-recording can be reproduced.

[Brief description of the drawings]

FIG. 1 is a head arrangement of a rotary head drum according to an embodiment of the present invention, FIG. 2 is a timing chart of post-recording, FIG. 3 is a block diagram of an embodiment of a recording / reproducing circuit, and FIG. FIG. 5 is a tape format of the rotary head drum of the VTR, and FIG. 6 is a timing chart of the conventional rotary head drum. 1 ... Rotating head drum, 2,2 '... Flying erase head, 3,4,5,6,7, ... Head.

Claims (1)

(57) [Claims] A magnetic tape is rotated and scanned, one track is divided into a first area and a second area, and different types of information are recorded / reproduced in each area, and two tracks are recorded / reproduced in one rotation. A recording / reproducing apparatus having a head drum, comprising: first and second two heads used for recording / reproducing in the first area and the second area; and a second area for recording in the first area. A third one head used for reproduction, and fourth and fifth two heads used for recording in the second area.
And a flying erase head for erasing an area necessary for post-recording one of the first area and the second area. The first and second heads are brought close to each other until the reproduction machines in the area are close to each other, and the recording and reproduction machines by the first and second heads and the first and second heads by the flying erase head At the time of recording / reproducing at the time except for the time of erasure for recording, the third head is arranged in a range where reproduction of the second area overlapping with recording of the first area is performed, and A rotary head drum in which the fourth and fifth heads are arranged in a range in which recording of the second area is performed without overlapping at times other than when reproducing by the second head; Recording and reproducing apparatus characterized by.