JP2569553B2 - Video tape recorder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video tape recorder in a helical scan type video tape recorder, and more particularly to recording a video signal by allocating a plurality of tracks to a recording field of one field. The present invention relates to a video tape recorder for performing reproduction.

[Summary of the Invention]

The present invention relates to a method for recording and reproducing a video signal by allocating a plurality of tracks to a recording area of one field in a helical scan type video tape recorder.
As the track number m (m = 1, 2,... M) of M (M ≧ 2) tracks assigned to the recording area of the field,
A video signal of N lines in one field represented by a time series signal Sn (n = 1, 2,... N) is expressed as _nm = m + (n-1) .M
By rearranging the data in the track of each track number m by rearranging the data in the order of one field in the line order, it is possible to obtain a reproduced video signal having good image quality without image loss during the reproducing operation in the shift mode. It is to be.

[Conventional technology]

Generally, in a helical scan type video tape recorder (hereinafter, simply referred to as VTR), one track is allocated as a recording area of one field, and azimuth recording of one track / one field in which recording azimuths of adjacent tracks are different. To do.

For example, in an NTSC helical scan type VTR for recording and reproducing one frame of interlaced 525-line video signal composed of the first field and the second field as shown in FIG. 6, the frame frequency (30H
The two video heads having different azimuth angles provided at 180 ° opposite to each other on the rotating drum rotating at z) are switched at the field frequency (60 Hz) to change the tracks TR ₁ and TR ₂ on the magnetic tape 1 shown in FIG. by this scanning, and recorded in the first track TR ₁ in which one of video heads video signal of the first field from the first line to the 262 line scans, the second field from the first 263 lines up to the 525 line Is recorded on a _second track TR2 scanned by one video head.

Further, in the helical scan type VTR, due to the restriction on the S / N of the recording wavelength, the number of rotations of the drum is set to an integral number (M) of the frame frequency, and M tracks are allocated as a recording area of one field. Sometimes azimuth recording of / 1 field is performed.

For example, in the NTSC helical scan type VTR, the rotating drum is driven at a frequency twice as high as the frame frequency (60 times the frame frequency).
Hz), and switching the 180 ° facing video head at twice the field frequency (120 Hz), as shown in FIG. , The video signal of each field is divided into two, and the first track TR ₁ scanned by one of the video heads records the first line to the 131st line,
The the second track TR ₂ to scan the other video head 1
From 32 line to 262 line is recorded, to record the third track TR ₃ in which one of the video head scans the first 263 lines up to 393 lines, the fourth track TR ₄ to scan the other video head Is recorded from the 394th line to the 525th line.

[Problems to be solved by the invention]

The NTSC video signal of 525 lines per frame is composed of the first field and the second field constituting one frame.
Each video signal in the field forms one image having a field correlation as shown in FIGS. 9A and 9B. However, in the helical scan type VTR, one image is generated as described above. When M tracks are assigned as a recording area of a field and azimuth recording of M tracks / field is performed, for example, if M = 2, one image indicated by a video signal of one field is vertically arranged. Since the data is recorded on two tracks at different azimuth angles after being divided into two parts, when a reproduction operation in a shift mode such as still reproduction, slow motion reproduction or quick motion reproduction is performed, the reverse azimuth existing every two tracks is performed. The video signal recorded on the track No. cannot be reproduced, and the upper half or lower half of the image is lost as shown in FIG. My, there is a problem that it is impossible to reproduce the entire one image in shift mode.

Therefore, the present invention has been made in view of the above-described conventional problems,
An object of the present invention is to provide a video tape recorder capable of reproducing a high quality video signal representing an entire image in a shift mode in a helical scan type VTR that performs azimuth recording of M tracks / one field.

[Means for solving the problem]

In order to solve the above-mentioned problems, the present invention writes two field memories and a video signal of at least one field in one field memory and reads a video signal stored in the other field memory. Write / read control means for reading a video signal stored in one field memory and writing at least one field of video signal in the other field memory; and a video read from the two field memories A rotating drum provided with a pair of video heads 180 degrees opposite to each other for recording a signal, and drum control means for controlling the number of rotations of the drum; m (m = 1,2
··· M), when M (M ≧ 2) tracks are assigned, a video signal of one field and N lines indicated by a time-series signal Sn (n = 1, 2,... N) Is written into the field memory, and the video signal is read out from the field memory by rearranging the video signal in a line order of n _m = m + (n−1) · M for each field, and the drum control means determines the number of rotations of the drum. The video head is controlled to M times the frame frequency, and the video head sequentially records the video signals in the line order read from the field memory on the track of each track number m.

[Action]

In the video tape recorder according to the present invention, M (M ≧ 2) where the track number is indicated by m (m = 1, 2,... M)
When a track is assigned, the time-series signal Sn (n
= 1,2... N), the video signal of N lines in one field is written into the field memory, and the video signal is read from the field memory every field in the line order of n _m = m + (n−1) · M. And read it out. Then, by controlling the number of rotations of the drum to be M times the frame frequency, the video head sequentially records the video signals in the line order read from the field memory on the track of each track number m. For example, when M = 2 and recording is performed on two tracks of 262 lines in one field, as shown in FIG. 3, video signals of odd lines are sequentially read from one field memory in the first half of one field period. The video signal of the even line is read out from the one field memory in the latter half of one field period. A video signal is similarly read from the other field memory. In other words, the write / read control means reads the video signal evenly for every two tracks in line units, as shown in FIG. 1, so that the odd-numbered line number (2 _nm -1) of 131 lines is obtained. tracks odd video signal of the track number (TR _1, TR ₃₎
And the video signal for 131 lines of the even line number (2 _nm ) is recorded on the track (TR ₂ , TR ₄ ) of the even track number.
To record.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of a recording system of a helical scan type video tape recorder (hereinafter, referred to as VTR) in which recording of two tracks per field is performed by applying the present invention. NTSC system video signal is (S _iN) is supplied, the input video signal (S _iN) is the signal through the input terminal 10 sync separator 11
And an analog / digital (A / D) conversion circuit 21.

The sync separation circuit 11 separates a sync signal superimposed on an input video signal (S _IN ) and supplies the sync signal to a clock generation circuit 12 and a timing generation circuit 13. The clock generation circuit 12 forms a 4 fsc sampling clock, a memory access clock, an address clock, and the like synchronized with the synchronization signal. Note that fsc is a subcarrier frequency in the NTSC system. The sampling clock obtained by the clock generation circuit 12 is analog / digital (A /
D) Conversion circuit 21 and digital / analog (D / A) conversion circuit 24
The memory access clock is supplied to the two field memories 22A and 22B, and the address clock is supplied to the write address counter 14 and the read address counter 15. Further, the timing generation circuit 13 forms a write / read control signal (W / R), a reset signal, a switching control signal (S ₁ , S ₂ ), and the like based on the synchronization signal. The above timing generator
The write / read control signal (W / R) obtained at 13 is supplied to each of the field memories 22A and 22B, and the reset signal is supplied to the write address counter 14 and the read address counter 15; (S ₁ , S ₂ ) are supplied to signal selection circuits 23 and 27.

Further, the A / D conversion circuit 21 is provided with a 525 line N of one frame composed of a first field and a second field as shown in FIG.
For input video signal TSC system (S _IN), the sampling clock of 4fsc supplied from the clock generating circuit 12, and quantized sampling said input video signal (S _IN), to form the video data. A / D conversion circuit 21
Are supplied to the first and second field memories 22A and 22B.

The first and second field memories 22A and 22B are:
Each has a storage capacity for one field, and a write / read control signal (from the timing generation circuit 13) supplied from the timing generation circuit 13 so that when video data is written to one, video data is read from the other. W /
R), the writing operation and the reading operation are alternately switched every one field period, and the storage location of the video data is sequentially specified by the write address data supplied from the write address counter 14, and as shown in FIG. As shown, the video data of the first field is written to the first field memory 22A, and the video data of the second field is written to the second field memory 22B. Further, the first and second field memories 22A and 22B are stored in the first half of one field period from storage locations sequentially specified by the read address data supplied from the read address counter 15, as shown in FIG. The video data of the odd-numbered lines are sequentially read out, and the video data of the even-numbered lines are sequentially read out in the latter half of one field period.

That is, in this recording system, the line order of the video data is rearranged for each field by the first and second field memories 22A and 22B.

Then, the first and second field memories 22A,
The rearranged video data of the line order read from 22B is supplied to a digital / analog (D / A) conversion circuit 24 via a selection circuit 23 for selecting a field memory during a read operation, and the D / A conversion circuit Analogized at 24. The rearranged video signals in the line order obtained by the D / A conversion circuit 24 are supplied to a recording amplifier circuit 26 via a modulation circuit 25, and a pair of video signals are supplied from the recording amplifier circuit 26 via a head selection circuit 27. It is supplied to video heads 28A and 28B. The head selection circuit 27 is controlled by a switching control signal (S ₂ ) supplied from the timing generation circuit 13,
The pair of video heads 28A and 28B are controlled so as to be alternately selected every 1/2 field period. As shown in FIG. 3, the video signal of an odd line is used as a recording signal to one video head 28A. The video signal of the even line is supplied to the other video head 28B as a recording signal.

Here, the servomotor is applied by the servo circuit 32 so that the head motor 31 for rotating the pair of video heads 28A and 28B rotates at 60 Hz which is twice the frame frequency (30 Hz) in the NTSC system.

The pair of video heads 28A and 28B scan the magnetic tape 30 running at a constant speed by a tape running system (not shown) obliquely, and convert video signals in a 2-track / 1-field recording format shown in FIG. Azimuth recording is performed, video signals for 131 lines of odd line numbers (2 _nm -1) are recorded on tracks (TR ₁ , TR ₃ ) of odd track numbers, and 131 lines of even line numbers (2 _nm ) are recorded. Is recorded on tracks (TR ₂ , TR ₄ ) with even track numbers.

A reproducing system for reproducing a video signal recorded on the magnetic tape 30 by the recording system includes a modulation circuit 25 and a recording amplifier circuit in the recording system as shown in the block diagram of FIG.
26 is removed, a signal output terminal 50 is provided on the output side of the D / A conversion circuit 24, and a demodulation circuit 42 is connected to the movable end of the head selection circuit 27 via a reproduction amplification circuit 41. A configuration in which the output terminal is connected to the synchronization separation circuit 11 and the A / D conversion circuit 21 is used.

In this reproducing system, as described above, each track on the magnetic tape 30 on which the video signal is azimuth-recorded in the recording format of 2 tracks / 1 field is recorded by a pair of video heads 28.
A, by tracing in the order in 28B, as shown in FIG. 5, the reproduction signal of the odd lines of the video signal from one video head 28A to trace the track of the odd numbered (TR _1, TR ₃₎ is The other video head 28B that traces even-numbered tracks (TR ₂ and TR ₄ ) obtains a reproduction signal of a video signal of an even-numbered line every 1/2 field period. Can be

Reproduction signals alternately obtained by the pair of video heads 28A and 28B every 1/2 field period are output from a head selection circuit 27.
Is continuously taken out and supplied to the reproduction amplification circuit 41,
The signal is supplied from the reproduction amplification circuit 41 to the synchronization separation circuit 11 and the A / D conversion circuit 21 via the demodulation circuit 42.

The A / D conversion circuit 21 digitizes the reproduced video signal supplied from the demodulation circuit 42 based on a 4fsc sampling clock supplied from the clock generation circuit 12. From the A / D conversion circuit 21, odd-numbered lines of video data are obtained in the first half of one field period.
In the latter half of one field period, video data of an even line is obtained. As shown in FIG. 5, the video data obtained by the A / D conversion circuit 21 is alternately written in the first and second field memories 22A and 22B in the same line order on a field basis.

In this reproduction system, when reading the video data written in the first and second field memories 22A and 22B, the line order is rearranged in units of fields, and the first and second field memories 22A and 22B are rearranged. ,twenty two
By converting the video data read from B into an analog signal in the D / A conversion circuit 24, a reproduced video signal having a continuous line order is output from the signal output terminal 50 as shown in FIG. In addition, according to the reproduction system, for example, as shown by the arrow in FIG.
By performing variable-speed playback such as double-speed playback, for example, when a playback signal cannot be obtained by the other video head 22B,
A reproduced video signal of each field constituted as shown in FIG. 5 by the reproduced signal by the other video head 22B, that is, the odd-line video signal from which only the even-line video signal is lost is obtained at the signal output terminal 50. be able to.

In the above-described embodiment, the present invention is applied to a helical scan type VTR to perform 2-track / 1-field analog signal recording. However, the present invention is not limited to the above-described embodiment. M as a field recording area
The present invention can be applied to a helical scan type VTR that performs analog or digital signal recording of M tracks per field by allocating book tracks. That is, M (M ≧ 2) tracks whose track numbers are indicated by m (m = 1, 2,... M) are assigned as a recording area of one field in the helical scan type VTR, and the time-series signal Sn
(N = 1,2... N), the video signal of N lines in one field is rearranged for each field in a line order of n _m = m + (n−1) · M, An analog or digital signal may be recorded on the track in order.

〔The invention's effect〕

In the video tape recorder according to the present invention, the video signal of N lines in one field is recorded evenly over M tracks in a line unit by rearranging the line order with one field as one unit. When the video signal is lost, the entire image represented by the video signal of one field can be reproduced. In a video tape recorder that performs M track / field azimuth recording, one image is recorded in the shift mode. It is possible to reproduce a video signal with good image quality representing the whole.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a recording format of a video tape recorder according to the present invention, and FIG. 2 is a diagram showing a configuration of a recording system of a video tape recorder for recording a video signal in the recording format shown in FIG. FIG. 3 is a timing chart showing the operation of the recording system, FIG. 4 is a block diagram showing the configuration of the reproducing system of the video tape recorder, and FIG. 5 is a timing chart showing the operation of the reproducing system. It is. FIG. 6 is a schematic diagram showing a configuration of a video signal in the NTSC system, FIG. 7 is a schematic diagram showing a recording format of a general helical scan type VTR performing a recording operation of one track / one field, and FIG. FIG. 9 is a schematic diagram showing a recording format of a conventional helical scan type VTR performing a track / field recording operation, and FIG. 9 shows a reproduced image by the conventional helical scan type VTR performing a 2-track / 1 field recording operation. It is a schematic diagram. 10 Signal input terminal 21 A / D conversion circuit 22A, 22B Field memory 24 D / A conversion circuit 28A, 28B Video head 30 Magnetic tape TR _{1 to} TR ₄ Track

Claims (1)

(57) [Claims] 1. A field memory for storing a video signal, a video signal of at least one field is written in one field memory, and a video signal stored in the other field memory is read out. Writing / reading control means for reading stored video signals and writing at least one field of video signals in the other field memory; and for recording video signals read from the two field memories. A rotating drum provided with a pair of video heads 180 degrees opposite to each other, and drum control means for controlling the number of rotations of the drum, wherein the write / read control means has a track number m (m = 1 ,
When M (M ≧ 2) tracks indicated by (2... M) are assigned, the time-series signal Sn (n = 1, 2,.
N), a video signal of N lines in one field is written in the two field memories, and the video signals are written from the two field memories in a line order of n _m = m + (n−1) · M every one field. The drum control means controls the number of rotations of the drum to be M times the frame frequency, and the video head reads the video signals of the line order read from the two field memories on each track. A video tape recorder characterized by recording in order on a track of a number m.