JPH0670279A - Video signal recording/reproducing device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the picture quality even at the time of being unreproducible due to one head having the clogging by dividing the video signals into N blocks and recording the video signals successively in the unit of each divided block after dividing those signals in the time series order at every N line division in the order of line numbers of each block. CONSTITUTION:When the video signals of 525 lines per frame are recorded and reproduced, the signals of one field are divided into four tracks and then recorded and reproduced by four heads A-D. If the head B has the clogging, the signals recorded on the tracks 2 and 6 become unreproducible. Under such conditions, the lines 7-259 become unreproducible in N fields and the lines 269-521 become unreproducible in (N+1) fields respectively. These lines are separate from each other. Viewed at every field, one of four lines becomes a noise signal. Then a unreproducible line is replaced with the average value before the unreproducible line or the average value of the line signals before and after the unreproducible lines and therefore can be corrected. Thus the occurrence of noises can be suppressed on a screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a helical scan type V
The present invention relates to a video signal recording / reproducing apparatus in a TR (video tape recorder). More specifically, the video signal is recorded for each field signal, for example, if there are four, four
When the recording density is improved by recording or reproducing the same amount on each of the signal recording tracks on a line-by-line basis, among the four rotary heads corresponding to the four signal recording tracks. For example, if one piece becomes clogged due to dust or the like and cannot be played back, and the signal from the corresponding track is lost, the playback screen will not be degraded so much, or a special speed such as double speed playback will be used. The present invention relates to a recording / reproducing apparatus for preventing the reproduction screen from being deteriorated so much even when reproduction is performed.

[0002]

2. Description of the Related Art In a conventional VTR for recording a signal for each field on a plurality of tape tracks, as described in JP-A-57-123778, a plurality of signals for recording one field are divided and recorded. One of the tracks is discriminated as a signal track for special reproduction, only the upper portion of the image sample is recorded here, and only this track is reproduced by a dedicated head during special reproduction. However, during normal reproduction, the signals of all tracks that are divided and recorded are reproduced by using a plurality of heads corresponding to each track.

[0003]

In general, magnetic powder of tape or the like adheres to the magnetic head to cause clogging, which deteriorates the reproduction signal amplitude. When such signal amplitude deterioration occurs, Therefore, the signal quality is greatly damaged. In the signal recording format described in JP-A-57-123778, no consideration is given to maintaining image quality when such a situation occurs,
Therefore, when the head for reproducing the track recorded by collecting the upper portion of the image sample, which is the characteristic thereof, is clogged, there is a problem that the reproduction image quality is greatly deteriorated. Also, in order to perform special reproduction, if a head and a signal reproduction circuit used for normal reproduction are used, the image quality will be greatly deteriorated. Therefore, it is necessary to provide a reproduction head and a signal reproduction circuit dedicated to the head and use this. It was inconvenient in the sense that you had to prepare a special one.

An object of the present invention is to solve the above-mentioned problems of the prior art, and in a helical scan type VTR, when a signal for each one field is divided into a plurality of tracks for recording and reproduction, the tracks are recorded on the tracks. Even if, for example, one head of the corresponding heads is clogged and reproduction becomes impossible, resulting in the loss of a collected signal on one track, the quality of the reproduced image is not significantly deteriorated. An object of the present invention is to provide a video signal recording / reproducing apparatus capable of performing special reproduction at various speeds without causing a significant deterioration in image quality without using a dedicated head or a reproduction circuit.

[0005]

A VTR for recording / reproducing an NTSC television signal will be described below. Of course, it is noted in advance that the number of lines in one field and the recording / reproducing system do not affect the essence of the present invention. There are several methods for dividing the video signal for one field into a plurality of signal recording tracks. However, in order to perform special reproduction while the signal recording track is obliquely scanned (helical scan) with an ordinary head without providing a special reproduction dedicated head, for example, in the case of an NTSC system television signal, 262.
It is advantageous to divide the image signal for one field consisting of five horizontal scanning lines (lines) in units of lines for the convenience of reproduction signal processing. By the way, recording is performed line by line on the first signal recording track in sequence from the first line of the 262.5 lines forming one field,
When the track becomes full, the second signal recording track is simply recorded from the next following line.
Consider a case where a signal for a field is divided line by line in line units. Since the VTR has a high recording / reproducing signal frequency, a head corresponding to each signal recording track is used, and recording / reproducing is often performed by a multi-channel system by a plurality of such heads. In the signal reproduction, the deterioration of the signal S / N directly leads to the deterioration of the reproduced image. Therefore, when one of the plurality of heads is clogged and the reproduction signal S / N from the head is significantly deteriorated, The signal of the track corresponding to that head cannot be reproduced. Therefore, as described above, in a simple signal division method in which a signal for one field is assigned to a plurality of tracks in a line order by a plurality of lines, when a certain head is clogged, the continuous tracks on the tracks corresponding to the head are generated. You cannot play back multiple lines. For example, when a 1-field signal is divided and recorded on 4 tracks, if a 1-track signal cannot be reproduced, a line corresponding to 1/4 of the screen cannot be continuously reproduced, and 1/4 of the screen is Collectively, it will be missing. Further, since the signal missing position on the screen is fixed at the same position in each field, it is impossible even if an attempt is made to compensate for the missing signal by taking the field correlation or the frame correlation. Therefore, in the present invention, in the same signal recording track, the signals for one field are divided into line units so that lines which are adjacent to each other on the screen (that is, lines in order) are not recorded in each track. Record separately.

[0006]

As a result, even if the head corresponding to a certain track is clogged and the signal recorded on that track is no longer reproduced, the lines that have not been reproduced are mutually separated on the screen of one field. The line will be at a distance. The signals of these non-reproduced lines can be easily supplemented by taking the line correlation using the signals of the normal lines reproduced by the adjacent and non-clogging other heads. It is possible to prevent deterioration of image quality. in this way,
In order to prevent lines that are adjacent to each other on the screen from being recorded on the same signal recording track, when signals of a plurality of lines forming one field are divided and recorded on N tracks, one field is formed. Among the plurality of lines to be recorded, the lines picked up every Nth line from the first line are collectively recorded on the first track, and the lines similarly picked up every Nth line from the second line are collectively recorded to the second line. You can record on the track. Of course, even if such a simple regular division method is not used, for example, if a line on one track is recorded, the next line is recorded on any of the other (N-1) tracks. All you have to do is However, regular signal division is more convenient in terms of hardware configuration.

On the other hand, when special reproduction such as double-speed reproduction is performed using an ordinary head, the traveling locus of the reproducing head on the tape becomes a locus that crosses the track diagonally. Therefore, the head can only reproduce a part of the signal on each track. In particular, when performing integral multiple speed reproduction, reproduction may occur in which among the plurality of tracks in which signals for one field are recorded separately for each field, only the recording signal at the same screen position can be reproduced when viewed for each field. There is speed. Therefore, when performing such special reproduction, even if the above-mentioned signal division is performed, a plurality of continuous lines cannot be reproduced, and a noise band appears on the screen, not to mention line correlation but also field correlation and frame correlation. Since they cannot be obtained, they cannot be used to supplement the missing signal.

Of course, it is possible to perform signal division so that unreproducible lines are evenly scattered on the screen only for special reproduction using a certain specific speed, but even in that case, changing the reproduction speed has no effect. .

Therefore, the relationship between the line position on the screen and the recording position on the track is sequentially changed between the fields.

For this reason, N tracks from the Nth line are divided into N tracks as opponents for dividing and recording a 1-field signal, with the beginning of each field as a division standard.
Recording is again performed for each book so that the division standard for each predetermined number of fields is increased by a predetermined number of lines from the beginning of the field. Of course, as described above, the division method and the increment amount of the division standard may be irregular, but it is still advantageous in terms of hardware configuration.

In order to perform the above signal division, consider a numerical value M that increases by a fixed number for each predetermined field and returns to zero when the value reaches the number of lines forming one field. Then, for each field, the (M-1) th line is arranged in order starting from the (M-1) th line to the last line of the field, and then from the line at the beginning of the field to M
A virtual field in which the lines up to the line are arranged in order is generated.

The signal is divided into each track based on this virtual field. For N tracks, the Nth line from the head of the virtual field to the Nth line, respectively.
The line taken for each book may be recorded. If such a signal division type recording / reproducing apparatus is used, even if only the signal recorded at the specific position of each track can be reproduced at the time of special reproduction, the line position on the screen of the reproduced signal is different for each field. . Therefore, if the signal of the line that could not be reproduced is retained and used as the signal of the line that was reproduced in the previous field, it is possible to prevent the noise band from being generated on the screen.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a schematic diagram showing a divided recording format of a signal for one field on a plurality of tracks according to the present invention as an embodiment of the present invention. In this embodiment, 5 per frame
This is an embodiment in which the present invention is applied to a VTR which records and reproduces a video signal composed of 25 lines (numbered in scanning order, line 1, line 2, ... Line 524, line 525). In this embodiment, the signal of one field is divided and recorded on four tracks. In the present embodiment, the lines 524 and 52 during the vertical blanking period.
5, 1-5 and lines 262-267 are not recorded on the track. In FIG. 1, 1 to 8 are signal recording tracks. 1A shows the arrangement of signal recording tracks on the tape, and FIG. 1B shows the arrangement of signal lines on each track. Each track 1-8,
As indicated by A to D in FIG. 1A, the signal amounts obtained by dividing the signal for one field into four are recorded in four tracks corresponding to the four tracks respectively recorded. Recording and reproduction are performed by the four heads.

Further, in FIG. 1B, the numbers shown in the squares in each of the tracks 1 to 8 represent the line numbers of the video signal. The signal recording tracks 1 to 8 are shown in FIG.
As shown in (a), the tape is obliquely arranged on the tape.
The signal of the field N is divided into four tracks 1 to 4,
Similarly, the signal of the next field (N + 1) is track 5
It is divided into 8 parts and recorded on the tape. Four
Each divided signal is recorded in this order on a corresponding track on the tape by four heads A to D, respectively. Therefore, tracks 1 and 5 are A, tracks 2 and 6 are
B, tracks 3 and 7 are recorded by C, tracks 4 and 8 are recorded by D, and signals are reproduced in the same combination during reproduction. As shown in FIG. 1B, on track 1, lines 10, 14, which are lines extracted every four lines from line 6 of the head line among the signals recorded on the tape in field N, 18, ..., 25
4, 258 signals are recorded.

Similarly, as shown in FIG. 1 (b),
On track 2, lines 11, 15, 19, ..., 255, 2 which are lines extracted every 4 lines from line 7 which is the second line of the recording signal of field N.
The signal of 59 is a line extracted every four lines from the line 8 which is also the third line on the track 3, the signals of lines 12, 16, 20, ... In the same manner, signals of lines 13, 17, 21, ..., 257, 261 which are lines extracted every four lines from the fourth line, line 9, are recorded.

The signal in field (N + 1) is likewise shown in FIG.
As shown in (b), as lines extracted every four lines, the track 5 has lines 268 to 272, 276, ...
516 and 520, the track 6 has lines 269 to 273, 277, ... 5 as the second line.
17, 521, but track 270 to lines 274, 278, ..., 51 as the third line on track 7.
8, 522, and on track 8 the fourth line from line 271 to line 275, 279, ...
519 and 523 are recorded respectively. Thereafter, in the fields (N + 2) and thereafter, the signals of each field are similarly divided and recorded on every four tracks.

Next, the effect of the video signal recording / reproducing apparatus according to the present invention of the divided recording / reproducing system as shown in FIG. 1 will be described with reference to FIG. FIG. 2 shows that, in the signal division method of FIG. 1, of the four reproducing heads, a head (referred to as a B head) for reproducing a track labeled B in FIG. It is a figure which shows the reproduction | regeneration condition of the video signal (image signal) when a signal is no longer acquired. When the B head is clogged,
The signals recorded on the tracks 2 and 6 cannot be reproduced at all. In the conventional method in which a continuous signal in the order of signal lines is recorded on each track as a partner for dividing and recording a signal of one field, continuous plural lines cannot be reproduced due to such clogging of the head. As described above, a noise band is generated on the next screen.

However, according to the method of the present invention, even if the signals of tracks 2 and 6 in FIG. 1 cannot be reproduced at all, the unreproducible line is line 7 in N field as shown in FIG. 1B. 11, 15, 19, ...
255 and 259, and lines (269, 273, ..., 517, 521) in the (N + 1) field, which are mutually discrete lines. Therefore, the reproduced signal is as shown in FIG. 2 on the screen, and one line out of every four lines becomes a non-reproducible noise signal in each field. Therefore, these unreproducible signal lines can be easily supplemented by the signals of the lines before and after the line correlation of the image signal, and the noise on the screen can be removed. For example, in FIG. 2, the unreproducible line 7 can be replaced by the signal of the preceding line 6 or by the average value of the signal of the line 6 and the signal of the subsequent line 8, Similarly, line 269 in the next field can be easily replaced by the signal on line 268 or the average value of the signals on line 268 and 270. Hereinafter, the unreproducible lines such as the shaded lines 11, 15, 273, 277 in FIG. 2 can be easily corrected, and the noise generation on the screen can be suppressed.

In the above embodiment, when the head is clogged, the reproduction becomes impossible and the position of the corrected signal line on the screen is the same in both odd and even fields (actually, due to interlacing). As shown in FIG. 2, the odd and even fields come to be adjacent to each other). According to the present invention, the position of the line that becomes unreproducible when the head is clogged is made different between odd and even fields, and the lines to be corrected are scattered, so that the visual quality is deteriorated. Can be reduced.

In addition, not only the line correlation but also the field correlation can be corrected by this. If necessary, both correlations can be used in combination to further reduce the image quality deterioration. An embodiment of the present invention will be described below with reference to FIG. FIG. 3 shows the first part of the present invention.
It is a schematic diagram which shows another example of the format which records and records the signal of a field on a some track. Also in this embodiment, the video signal to be recorded is the same as that in the embodiment of FIG.

In FIG. 3, 11 to 18 are signal recording tracks. 3A and 3B show the arrangement of recording signal tracks on the tape and the arrangement of signal lines on each track, as in FIG. Further, as in the embodiment of FIG. 1, the signal of one field is divided and recorded on four tracks, and each of the tracks 11 to 18 is A to D, as indicated by A to D in FIG. Recording and reproduction are performed by the four heads. In addition, each track 11 to 18 in FIG.
The numbers inside the squares represent the line numbers of the image signal, as in FIG. 1 (b). Signal recording tracks 11-
18 is obliquely arranged on the tape as shown in FIG. Field N signals are track 11-1
Similarly, the signal of the next field (N + 1) is divided into four tracks 15 to 18 and recorded on the tape. The four-divided signal corresponds to the recording order of the track on the tape, and is divided into 4 of A to D, respectively.
It is recorded by individual heads. Therefore, track 1
1 and 15 are A, tracks 12 and 16 are B, track 13
Heads C and 17 and tracks 14 and 18 are recorded by the head D, and signals are reproduced in the same combination during reproduction. As shown in FIG. 3B, the signals of the field N are recorded on the tracks 11 to 14 in exactly the same manner as in the embodiment of FIG. On the other hand, on the tracks 15 to 18, the signal of the field (N + 1) is cyclically shifted by one line in the field and then dividedly recorded by the same method as the division method to the tracks 11 to 14. Therefore, as shown in FIG.
Track 15 has line 269 at the head and line 27
3, 277, 281, ..., 517, 521, but track 16 has lines 270, 274, 278 ,.
8, 522, but tracks 27 have lines 271, 27
5, 279, ..., 519, 523, and track 18 has lines 272, 276, 280 ,.
Finally, each line 268 is recorded.

In the following fields (N + 2) and (N + 3), the recording is divided into four tracks in accordance with the odd / even of the fields, similar to the fields N and (N + 1). In the present embodiment, the fields (N + 1) (N + 3, N +
(5, ... also) is cyclically shifted by one line within the field, but it goes without saying that the number of lines to be shifted can be arbitrarily selected. In addition, the field (N +
1) (same for N + 3, N + 5, ...) Is the same as that of the embodiment of FIG. 1, and field N (same for N + 2, N + 4, ...)
Alternatively, a cyclic shift may be performed in line units, and the same effect is obtained.

Next, the effect of the embodiment of FIG. 3 will be described with reference to FIG. FIG. 4 is a block diagram of the signal division method of FIG.
FIG. 11 is a diagram showing a situation of reproducing an image signal when a B head is clogged out of four reproducing heads D to D and a reproduction signal cannot be obtained from the B head.

When the B head is clogged, the signals recorded on the tracks 12 and 16 in FIG. 3 cannot be reproduced. However, since the signals are divided and recorded on the tracks 11 to 18 so that the signal lines are arranged as shown in FIG. 3B, even if the signals on the tracks 12 and 16 cannot be reproduced at all, Unreproducible lines are lines 7, 11, 15, 19, ... 255, 259, 27.
0, 274, ..., 518, 522. Therefore, the reproduced signal is as shown in FIG. 4 on the screen, and the positions of the unreproducible lines on the screen are discrete both in the same field and in the adjacent field. As a result, these unreproducible signal lines can be easily corrected by the signals of the lines before and after it, and the noise on the screen can be removed, and the lines to be corrected are scattered on the screen. Image quality degradation is reduced.

Further, in the case of such signal division, not only the line correlation but also the field correlation can be corrected, so that the image quality can be further improved. In the above description of the embodiments, only the clogging of the head has been described. However, the same applies to the case where the signal of one track cannot be reproduced due to the loss of synchronization when the signal is reproduced from the track. effective.

Next, an embodiment of a signal division method which is realized by the video signal recording / reproducing apparatus according to the present invention and is advantageous for special reproduction will be described with reference to FIG. FIG. 5 is a schematic diagram showing a format when a signal of one field is dividedly recorded on a plurality of tracks in consideration of special reproduction and a signal reproduction situation at the double speed reproduction in the present invention. Also in this embodiment, the video signals to be recorded are the same as those in both the embodiments shown in FIGS. In FIG. 5, 21 to 34 are signal recording tracks. Each track is recorded with different azimuth angles between adjacent tracks in order to avoid crosstalk. FIG. 5A shows the arrangement of the signal recording tracks on the tape and the scanning locus of the reproducing head during double speed reproduction.
(B) shows the arrangement of signal lines on each track. Similar to the above-described embodiments, the signal of one field is divided and recorded on four tracks, and each of the tracks 21 to 34 is A to D as shown by A to D in FIG. Recording and reproduction are performed by the four heads. The four heads A to D have two types of azimuth angles, and A and C and B and D have the same azimuth angle. Heads A to D are evenly arranged on the cylinder at an angle of 90 °, and the head scanning loci during double speed reproduction are shown in FIG.
It is as shown by a to d in (a). The numbers inside the squares in each track in FIG.
3B shows the line number of the image signal as in FIG. 3B. The signal recording tracks 21 to 34 are diagonally arranged on the tape as shown in FIG. Field N
Signal is divided into four tracks 21 to 24. Similarly, the signal of the next field (N + 1) is divided into tracks 25 to 28.
The signal of the field (N + 2) is divided into four tracks 29 to 32 and recorded on the tape. Each track is recorded by four heads A to D, respectively, as indicated by A to D in FIG. 5A, according to the recording order on the tape.

As shown in FIG. 5B, the signals of the field N are extracted from the tracks 21 to 24 at the head line of the field and every four lines from the head line, as in the embodiment of FIG. The recorded lines are sequentially recorded for each track. Fields (N +
After the signal of 1) is cyclically shifted by one line in the field, it is similarly divided and recorded.

The process up to this point is the same as that of the previous embodiment shown in FIG. 3, but the following tracks 29 to 32 have a field (N +).
The signal of 2) is cyclically shifted by 2 lines in the field, and then dividedly recorded on each track, and the following tracks 33,
Similarly, for 34 and below, the amount of cyclic shift in each field is increased line by line and recorded separately on each track. From the above, the tracks 21 to 34
The signal lines of each field are arranged in each field as shown in FIG. When double speed special reproduction is performed, the scanning loci of the four reproducing heads A, B, C and D are track 21 as shown by a, b, c and d in FIG.
It will come across ~ 34 diagonally.

However, when azimuth recording is performed, the signals of tracks recorded by heads having different azimuth angles cannot be reproduced. Therefore, the heads A and C reproduce only the tracks recorded by the heads A and C, and the heads B and D reproduce only the tracks recorded by the heads B and D, and only the signals in the shaded portions in FIG. Is played. Since a signal with a poor S / N and a low signal level is not reproduced correctly, the signal shown in FIG.
In the double speed reproduction state, the signal in the shaded area in FIG. 5B cannot be reproduced as a correct image signal and becomes noise. In such a reproduction pattern, if the line position on the screen and the line recording position on the track are fixed for each field as in the embodiment of FIG. 1, a noise band occurs at the fixed position on the screen. Also, it cannot be corrected by line correlation or field or frame correlation.

In the embodiment of FIG. 5, however, the position of the reproducible signal line on the screen sequentially moves for each field.
Generation of a noise band can be prevented by holding the signals of the same line of the frame reproduced before that or the line of the same position of the field (actually, there is a shift due to interlacing). As described above, in the present embodiment, it is possible to minimize the deterioration of image quality during special reproduction.

In this embodiment, the four heads are evenly arranged on the cylinder at an angle of 90 °.
Other heads may also be in position, such as four heads arranged in close proximity with a step, or
Even in the special reproduction at a speed other than the double speed, although the pattern of the reproduced signal is different, the same effect of preventing the noise band is obtained. Also, an example has been described in which one line is used as the increment of the cyclic shift amount of the signal for each field, but the same is true even if another arbitrary number of lines is selected or the increment of the cyclic shift amount is changed for each field. The effect of can be obtained.

Next, an embodiment of an apparatus for recording / reproducing a video signal by the above-mentioned signal division recording system according to the present invention will be described with reference to FIG. FIG. 6 is a block diagram showing the hardware configuration (video signal recording / reproducing apparatus) of an embodiment of the present invention. The configuration of FIG. 6 is a configuration for recording / reproducing a signal in the format shown in FIG. 6, 41 is a video signal input terminal, 42 is a recording timing generation circuit, 43 is an A / D converter, 44 is a memory control circuit, 45 is a frame memory, 46 is a signal distribution circuit, and 47.
a to 47d are time axis expansion circuits, 48a to 48d are encoders, 49a to 49d are recording amplifiers, 50a to 50d are magnetic heads, 51a to 51d are reproduction amplifiers, and 52a to 5
2d is a time axis correction circuit, 53a to 53d are decoders, 5
4a to 54d are time axis compression circuits, 55 is a signal switching circuit,
56 is a synchronizing circuit, 57 is a reproduction timing generating circuit, and 58.
Is a memory control circuit, 59 is a frame memory, and 60 is D /
An A converter 61 is a video signal output terminal. Although the frame memories 45 and 59 are separately provided on the recording side and the reproducing side in FIG. 6, there is no difference in the operation described below even if one frame memory is shared for recording and reproduction. It does not spoil the essence. Video signal input terminal 4
The video signal including the video synchronization signal, which is input from the No. 1, is recorded in the recording timing generation circuit 42 and the A / D converter 4
Input to 3. The recording timing generation circuit 42 extracts the horizontal and vertical synchronization signals from the input video signal, determines the odd / even of the field, and further
A sampling clock of a predetermined frequency synchronized with the vertical synchronizing signal is generated. Then, this sampling clock is input to the A / D converter 43. Further, the horizontal and vertical synchronization signals, the odd / even determination signal, and the sampling clock are input to the memory control circuit 44. A / D converter 43
Then, the video signal input from the video signal input terminal 41 is sampled and converted into digital data by the sampling clock from the recording timing generation circuit 42.

The video signal thus digitized is sent to the frame memory 45. Memory control circuit 4
Reference numeral 4 includes a write address counter, a line counter, a read address counter, and a write pulse generator. The write address counter is a counter that is reset by the vertical sync signal of the odd field and counts the sampling clock. The line counter is a counter that is reset by the vertical sync signal of the odd field and counts the horizontal sync signal. The read address counter is a combination of a counter that is reset by a vertical synchronizing signal and counts a horizontal synchronizing signal, and a counter that is reset by a horizontal synchronizing signal and counts a sampling clock.

The write pulse generator is the A / D converter 43.
Digital data samples from the frame memory 45
It is a circuit that outputs a pulse for writing to the memory once in every sampling clock in synchronization with the phase of the write address. The memory control circuit 44 alternately outputs the write address and the read address once for each sampling clock, and supplies them to the frame memory 45 together with the write pulse. As the write address, the value of the write address counter is given as it is. The read address is 5 when the odd / even determination circuit of the recording timing generation circuit 42 detects an even field, that is, 5 when the input signal is an even field, and vice versa for the value of the counter that counts the horizontal synchronization signal. Sometimes 2
67 is added, and the value obtained by multiplying the value obtained by replacing the upper 2 bits with the least significant bit by the number of samples per line obtains an address that increases by 4 lines, and counts the sampling clock It is given by adding the values of the counters.

As a result, when the data of the odd field is written in the frame memory 45, the data of the even field is read every four lines in the order of four tracks divided into four, and conversely the data of the even field is written. If so, the odd field data is similarly read. In this way, it is possible to prevent the order of reading and writing data in the preceding and following fields from being disturbed between the input and output of the frame memory 45. The data read from the frame memory 45 is divided into four signals for each track by the signal distribution circuit 46, and the signals are input to the time axis expansion circuits 47a to 47d, respectively. The time axis expansion circuits 47a to 47d expand the time axis according to the winding angle of the tape around the cylinder and send signals to the encoders 48a to 48d, respectively. Encoders 48a-48
At d, a channel identification signal and a synchronization signal necessary for recording / reproducing to / from the tape are added and modulated for each channel, and the magnetic head 50 is passed through the recording amplifiers 49a to 49d.
The data a to 50d are recorded on the tape in the format shown in FIG. If the channel identification signal is added to each signal for one line, it is convenient for special reproduction.

On the other hand, on the reproducing side, the magnetic head 5
The signals of the respective tracks reproduced by the signals 0a to 50d are transmitted through the reproduction amplifiers 51a to 51d and the time axis correction circuit 52a.
To 52d and the synchronizing circuit 56. Synchronous circuit 5
At 6, the synchronizing signal is detected from the reproduced signal of each inputted track, and a synchronizing clock necessary for digitally processing the reproduced signal is generated and supplied to the time axis correction circuits 52a to 52d. A timing reference signal for reproduction signal processing is generated. This timing reference signal is supplied to the decoders 53a to 53d and the reproduction timing generation circuit 57. Time axis correction circuits 52a to 52d
Outputs the reproduced signal as a digital signal to the decoders 53a to 53d while demodulating the signal reproduced from the tape, removing the time base fluctuation included in the reproduced signal. The decoders 53a to 53d add a dropout detection flag to the time axis compression circuits 54a to 54d when detecting a dropout caused by recording / reproducing on / from the tape.
The signal data is output to d.

In the time axis compression circuits 54a to 54d, the time axis expansion is performed for each track signal in accordance with the tape winding angle on the cylinder in order to reduce the recording signal band by increasing the number of channels during recording. , Compress to the original time axis.
The signal of each track thus compressed on the time base is assembled into a continuous digital video signal of one channel by the switching circuit 55, and the memory control circuit 58 and the frame memory 5 are assembled.
9 is input. On the other hand, the reproduction timing generation circuit 57
Based on the timing reference signal from the synchronization circuit 56,
The horizontal and vertical synchronizing signals corresponding to the digital video signal output of the switching circuit 55 and the sampling clock of the digital video signal are generated and supplied to the memory control circuit 58. The sampling clock is also supplied to the D / A converter 60. The memory control circuit 58 includes a write address counter, an odd / even determination circuit, a read address counter, and a write pulse generator. The write address counter is
A counter that is reset by a horizontal synchronization signal and counts a sampling clock. The odd-even determination circuit determines whether the data to be written in the frame memory 59 is odd field data or even field data according to the channel identification signal of the digital video signal input to the memory control circuit 58. Is.

However, when a dropout detection flag indicating the occurrence of dropout is added to the channel identification signal, the previous judgment result is held.

The read address counter is a counter that is reset by the vertical synchronizing signal when the odd-even determination circuit detects an even field and counts the sampling clock. The write pulse generator is the same as the write pulse generator included in the memory control circuit 44 on the recording side. However, on the reproducing side, when the dropout detection flag is added to the channel identification signal, the write pulse is stopped during the one line period.

For the write address, line address data is calculated from the channel identification signal added to the signal to be written in the memory and the signal position from the track head, and the line address data is sampled per line. The value of the write address counter is added to the value obtained by multiplying by, and the result is given to the frame memory 59. As the read address, the value of the read address counter is given as it is. In this way, the frame memory 59 is alternately supplied with the write address and the read address once per sampling clock from the memory control circuit 58, and the write pulse is supplied at the timing of the write address. In this way, the data of each signal line is written in the frame memory 59 at the predetermined address position determined by the line number, and the data is sequentially read. Therefore,
Even if the order of the signals written in the frame memory 59 is changed due to the signal division during recording, the signals are output in order of the line numbers in the D / A converter 60 during reading.

Then, in the horizontal and vertical blanking periods, the signal portions which are not recorded / reproduced on the tape are returned to the corresponding fixed pattern data sequence to form a completely continuous digital video data sequence, and D / A conversion is performed. .
The reproduced signal converted into a normal analog video signal by the D / A converter 60 in this way is output from the video signal output terminal 61. Similarly to the recording side, the reading side and the reading side of the frame memory 59 on the reproducing side are arranged so that when one is an odd field, the other is an even field.
Care is taken not to cause an error in the time-series order of reproduced signals due to 4-channel divided recording / reproduction.

One of the four heads is clogged,
When the signal of a specific line cannot be reproduced as shown in FIG. 2, the decoders 53a to 53d detect the dropout, and the dropout detection flag including the channel identification signal is added. Memory control circuit 58
In the same manner as when the channel identification signal has the dropout detection flag, the writing pulse is stopped when the digital video data has the dropout detection flag. In this way, due to the operation of the memory control circuit 58, these unreproducible signals are not written in the frame memory 59. Therefore,
In the memory of the address where the signal of the non-reproducible line shaded in FIG. 2 should be stored, the signal of the same line of the frame that was correctly reproduced before that time remains as it is.

When the addresses on the frame memory 59 of these unreproducible lines are given as read addresses, the signals of the correctly reproduced frames before that are read out, so that the signals having frame correlation are automatically obtained. It has been replaced. In this way, the signal of the shaded line in FIG. 2 is corrected by the frame correlation, and the generation of noise on the screen is prevented. Here, a delay circuit for about two lines and an average value calculation circuit are provided in the input portion of the frame memory 59, and if the digital video data to be written in the frame memory 59 has a dropout detection flag, a write pulse Instead of stopping 1
The average value of the data before and after the line can be written. In the present invention, even if the head is clogged, continuous line dropout does not occur, and thus correction of the signal based on such an average value has a great effect in preventing image quality deterioration. Further, since the correction signal does not collect on the screen even if it is simply replaced with the data of the previous line, the deterioration of the image quality is small.

In the embodiment of FIG. 6, of the read address counters of the memory control circuit 44 on the recording side, the counter that counts the horizontal synchronizing signal is a load counter that returns to 0 when the number of lines recorded on the tape is counted. By loading 0 in the vertical sync signal of the odd field and 1 in the vertical sync signal of the even field, the signal recording / reproducing system of the format shown in FIG. 3 can be realized.

Further, the memory control circuit 4 on the recording side is also provided.
A field counter that counts the vertical sync signal and returns to 0 when the number of lines recorded on the tape is counted is added to 4, and the load value of the load counter that counts the horizontal sync signal in the read address counter is added to both odd and even fields. Assuming that the value of this vertical synchronizing signal counter is as shown in FIG.
The signal recording / reproducing system having the format shown in FIG.
At the time of special reproduction, only the signal not shaded in FIG. 5B is written in the frame memory 59 on the reproducing side, and its line number changes for each field. Therefore, each signal line on the screen is rewritten in the memory at an appropriate cycle, and a special reproduction image without a noise band can be obtained. Further, at the time of writing / reading data to / from the frame memory 45 on the recording side, the sampling order in each signal line is exchanged according to a predetermined law in addition to the above, or a line unit is set in the field corresponding to the sampling order in the line. Even if the reproduced signal becomes uncorrectable, for example, by cyclically shifting the data position with, the corrected signal will be scattered on the screen in sample units to facilitate correction and further reduce image quality deterioration after correction. It can be reduced.

For example, a read address counter of the memory control circuit 44 on the recording side is provided with a load counter for counting a horizontal synchronizing signal which returns to 0 when the number of lines per field recorded on two sets of tape is counted, and a vertical synchronizing signal A predetermined numerical value corresponding to each format described above (a counter that is reset is used in the example corresponding to the format of FIG. 1, but it is equivalent if 0 is loaded) on one side, and this on the other side. Load a numerical value with a fixed offset value added (however, if the numerical value exceeds the number of lines recorded on the tape, subtract the number of lines recorded on the tape from the added value) and generate the read address. Instead of the counter that sometimes counts the single horizontal sync signal described above, the value of the sampling clock counter Using these two sets of values obtained by switching the value of the horizontal synchronization signal counter alternately in response to even.

On the reproducing side, when the memory control circuit 58 generates the write address, the line address data is added with the offset value added to the load value of one of the two sets of horizontal synchronizing signal counters at the time of recording. (If the number of lines to be recorded on the tape is exceeded, as on the recording side, subtract the number of lines to be recorded on the tape from that number) and generate line address data and this number according to the odd / even of the sampling clock counter. May be alternately switched and used for generating the write address. FIG. 7 shows a state of the reproduction screen when the B head is clogged when a cyclic shift of the data position with an offset value of 2 is applied to the format of FIG. As is clear from FIG. 7, the unreproducible data indicated by the diagonal lines are evenly distributed on the entire screen, and can be easily corrected by the data in the previous field and the average value of the data in the preceding and following lines. It can be seen that the deterioration of image quality can be suppressed. As described above, the feature of the present invention is not lost even if the rearrangement of data is used in combination with the present invention according to another law. Although the present invention has been described above with reference to an example in which one field is divided into four tracks, it goes without saying that the present invention can be similarly applied even if the number of tracks to be divided is another number.

[0048]

According to the present invention, when one field is divided into a plurality of tracks and recorded, a plurality of recording / reproducing heads corresponding to the respective tracks are clogged so that the signals of the tracks can be reproduced. Even if it disappears, it can be easily corrected by using the line correlation of the image signal, and the corrected signal line positions can be dispersed on the screen.
It is effective in improving the playback image quality of TR. Further, even in special reproduction by a normal reproduction head, a reproduction signal capable of correcting a noise band can be obtained by frame correlation or field correlation, which is effective in improving image quality during special reproduction.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an effect of the embodiment shown in FIG.

FIG. 3 is a schematic view showing another embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an effect of the embodiment shown in FIG.

FIG. 5 is a schematic view showing still another embodiment of the present invention.

FIG. 6 is a block diagram showing a hardware configuration of an embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an effect of the embodiment of the present invention.

[Explanation of symbols]

 1-8, 11-18, 21-34 ... Signal recording track 43 ... A / D converter 44, 58 ... Memory control circuit 45, 59 ... Frame memory 60 ... D / A converter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number for FI Technical location H04N 5/783 H 7916-5C (72) Inventor Takashi Furihata 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Home Appliance Research Laboratory, Hitachi, Ltd.

Claims (3)

[Claims] 1. A scanning type recording / reproducing apparatus adapted to divide a video signal, which is repeated in a predetermined line number order, into a plurality of parallel and oblique tracks on a recording medium by a scanning recording means and to reproduce the divided signal. In the above, the video signal is divided into N (N is an integer of 2 or more) blocks so as to include a plurality of signals in a line unit per block for each signal of one field, and A signal dividing means for dividing a video signal into a signal having a time-series order of every N lines in the order of the line number of the video signal in a block, and the divided video signal is sequentially recorded in block units on the track by the scanning recording means. A video signal recording / reproducing device, comprising: 2. The video signal recording / reproducing apparatus according to claim 1, wherein the signal recording means outputs the divided video signal of the video signal on N consecutive tracks for each field thereof. A recording / reproducing apparatus for a video signal, comprising means for recording so as to sequentially and cyclically arrange in line number order. 3. A scanning-type recording / reproducing method in which an input video signal which is repeated in a predetermined line number order is divided into a plurality of parallel and oblique tracks on a recording medium and recorded by the recording / recording means and is reproduced. In the device, the input video signal is
When each block is divided into N (N is an integer of 2 or more) blocks so as to include a plurality of signals on a line-by-line basis, and in each block, every N lines in the order of the line number of the video signal. A signal recording unit that divides the divided video signal into a signal having a sequence order and sequentially records the divided video signal in the block by the scanning recording unit, and a signal in the block unit recorded by the signal recording unit. A signal reproducing means for reproducing, and a signal output means for converting the reproduced video signal in block units from the signal reproducing means into a signal in the same time series order as the line number order of the input video signal in the one field and outputting the signal. A video signal recording / reproducing apparatus comprising: