JPS58124382A - Recording and reproducing system of television signal - Google Patents

Abstract

PURPOSE:To process and eliminate missing of a recording reproducing signal based on the head blanking period, with a comparatively simple circuit constitution using a delay device. CONSTITUTION:A counter 1 is reset with a vertical synchronizing signal, a horizontal synchronizing signal is counted, the first and latter half of each field period are sectioned based on the result of count, and a switching signal is formed at a switching controller 2. The switching of a picture signal by a switching device 4 is controlled so that the timing of switching of the picture signal is within a horizontal blacking period. On the other hand, the input picture signal is applied to a terminal of the switching device 4 via the delay device 3, applied to the other terminal directly, the signal is given to an output terminal through alternate switching in response to the switching signal. In processing the picture signal with the circuit constitution like this, the vertical blanking period of a recording and reproducing picture signal is made coincident with the head blanking period and missing. This missing is eliminated with the compression and expansion of the picture signal time axis.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a television signal recording and reproducing apparatus capable of wideband recording and reproducing television signals from a diagonal scanning magnetic recording and reproducing apparatus, that is, a so-called helical VTR1. Regarding System E, it was specially designed to enable recording and reproducing over a wide band using a rotary head without causing signal dropouts.

This type of helical VTR has a relatively simple structure,
It is suitable for ships with small and lightweight magnetic recording and reproducing devices, and the rotation speed of the magnetic head can be adjusted to, for example, standard! It has the advantage of being relatively easy to perform broadband recording and playback by rubbing twice as much.

However, the problem with this type of helical VTR+ is that when the magnetic tape is wound diagonally Q around a drum that has a built-in rotating head and guides the magnetic tape to make it run. When recording and playing back using
The locus of the rotation of the rotary head along the cylindrical surface E of the drum (there is a section where the magnetic tape cannot make contact, and the magnetic head does not come into contact with the magnetic tape), resulting in a signal loss period in which recording and playback cannot be performed. The problem is that there is a head blanking period. Therefore, as mentioned above, the rotating head is operated at twice the normal speed, i.e., 10 fields/second of television signals (as opposed to
Rotation speed of 20 rotations (when rotating the iron magnetic head,
While the magnetic tape goes around the same cylinder mI of the drum. It is possible to record video signals for i fields, but since there is a -1 series of head blanking periods, the vertical flanking period of each field can be matched with its head blanking period (even if the vertical flanking period of each field is made to match its head blanking period, The central portion of each field ζ is affected by the next head blanking period, causing a dropout of the recording/playback signal.Q.The image period between each field of the television signal ζ causes such a dropout of the recording/playback signal. As mentioned above, if the rotational speed of this magnetic head is twice that of Nishinomiya (limited to 60 fields per second for a telegraph bow),
If the number of rotations per second is an integer multiple of the normal rotation speed of the magnetic head being rotated (of course, for example, /j times 1.2.Jj times, etc.) The number of revolutions per second of the magnetic head is made to match the number of fields per second Q so that the head franking period (this is a problem that cannot be avoided as long as it is difficult).

In order to solve the problem of helical VTE of the edge F scanning method (in order to solve the problem of missing recording/reproducing A No. The recording/reproducing signal of each rotation/rad (or Only the signal portion of the head franking period is used as the recording/playback signal of the auxiliary rotary head.
Therefore, the complexity of the mechanism for providing a plurality of rotary heads with different rotations (rotation < jL phase) and the respective rotary heads Q
The problem of complicating the circuit configuration for combining and consecutively recording and reproducing signals is that when it is necessary to rotate the magnetic head at a desired rotational speed (this is difficult for conventional diagonal scanning type helical VTRs). This was a major drawback.

The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks, to simplify the mechanism of a diagonal scanning type helical VTR 1, and to use only a single rotating head.
Moreover, it is an object of the present invention to provide a television signal recording and reproducing system that can process and eliminate omissions in recording and reproducing signals due to head blanking periods using a simple circuit configuration.

First, the television signal recording and reproducing method of the present invention (c) The number of revolutions per second exceeding the number of fields per second of the television signal (a magnetic head rotating with a trowel (which scans the magnetic tape diagonally to record the above-mentioned television signal). When recording and reproducing, the field period of the television signal is divided into a plurality of sections, and at least one of them is (by changing the time axis of the television signal in the interval (by rubbing) so that the television signal in any interval can be recorded on the magnetic tape during a period excluding the head blanking period; The television signal is reproduced by changing the time axis of the television signal in at least the section in which the time axis was not changed during recording of the television signal reproduced from the magnetic tape. The plurality of sections in the signal section are made to be continuous.

Hereinafter, the present invention will be described in detail by way of embodiments with reference to the drawings.

The present invention is a helinonol VTR using a single rotating head.
Based on the blanking period, the image period in each field period of the pre-recorded signal (which occurs in the recorded raw signal) is eliminated by delay circuits, switches, switching controllers, time axis converters, etc. combination (comparatively m or f,
f circuit case (this is how it is processed.

ψ(Δ) / When recording and reproducing from a helical VTR f a cylinder quality No. 1 television with a frame with 7715 scanning lines and a vertical flanking period length of 410 scanning lines, i.e. ll-0H, the above-mentioned head flanking The present invention deals with the problem of color loss in recording and reproduction due to Q as follows.

High-definition telephony signals like those mentioned above every second! Helical VTR using a single magnetic head with 0 revolutions For image reporting in the first half of the field period, as usual, the vertical flanking period must match the head flanking period and the timing can be recorded as is, or the lower part of the screen, i.e., the second half of the field period, can be [lII] 1 image count, signal frangi/period length 110 ■ (half of) 20H is slow, Q will occur between the first half and the second half.

The blank period of H is matched with the head flank period (this is recorded).

Ichiriki, play the first picture of the first half of the field period that was recorded using Q as described above. (20H of blank space between the reproduced image in the latter half of the field period is made continuous, and the image signal in its original form is restored.

The aspect of such image signal processing is shown in FIG. The vertical flank A-link period of 20 minutes is divided into 20 II parts and divided into the first and second halves of the field period, and the blank period of 2oH is made to coincide with the head flank period O (this servo control is performed). Note that since the number of scanning lines in the / frame is an odd number, as mentioned above (either the front or rear half of the divided odd-even field periods is less than 1. In the illustrated example, this corresponds to the first half of the first field period.
Such an increase in the number of scanning lines can be applied to either the front or rear half (even if this setting is made, a single column will not occur).

Next, an example of a circuit configuration for performing image signal processing in the manner described above is shown in FIG. The synchronization signal H is counted, and based on the count result number, the front and rear parts of each field period are divided in the manner described above. 'l Controls the switching of the image information so that the timing of the image switching is within the horizontal blanking period. On the other hand, the input image signal is
One switching terminal Q of the switching device t is supplied through the delay device 3 having a delay amount of and leads to the output terminal.In addition, in the circuit configuration shown in the figure,
During recording and playback (this is common (this can be used, switch 1.tl is the polarity θ for switching between images)), and when recording and internally (this is the opposite at L:). In addition, the circuit configuration does not process the iron image signal, and I1 is the part of the vertical flanking l131141 of the recording +li Ikuyama 1 family name.
\ Soto franking period (although this may occur coincidentally, there is also a possibility that the signal portion of the vertical franking period will be disqualified rj) (this will prevent recording and playback.
r f, j″″') +r- can be used to add the time 1lli1 of the image when recording, and to expand and restore it when creating the image. .

In other words, when the vertical crack/kink period (recording P by multiplexing other signals, such as still image signals, test chemicals, time coats, etc.) of the television hM occurs (this (yu,
As mentioned above, when processing an image signal using a relatively simple circuit configuration using a delay device, etc., it is necessary to avoid the LQ loss during the vertical flanking period, and such signal loss can be avoided on the image signal time axis. Figure 3 shows a mode of image signal processing in which the time axis of the image signal is compressed during recording to eliminate the head blanking period. However, when playing back, the time axis of the town image signal is expanded and restored.

At this time, during recording (the switching point between the front and rear halves of the divided field period does not necessarily have to be within the horizontal flanking period, but can also be within the image period).

An example of a circuit configuration for performing image signal processing in the manner described above is shown in FIG. The time axis control when reading data from the memory device j and the time axis control when reading from the memory device j are carried out by the memory control device B independently from each other, and the image signal processing mode described above is performed. Therefore, when recording a video signal (this is the time axis of the input video signal), the time axis of the output video signal is compressed,
Also, when playing back a video signal, Q is the time axis of the input video signal (
In comparison, the time axis of the output video signal is expanded. A memory device to perform such time axis compression/expansion! 51, when the video signal is written and read, the write address counter 7 and the read address counter (from which the write clock signal (1) and the read clock signal (,
2) are counted by 10,000 fields each, and sequentially generate write address signals and read address signals for the memory device j (Q) and supply them to the memory control device (6). In this case, the input image signal is sampled from the write clock signal (1), and the above-mentioned write address signal (accordingly, the input image signal is sequentially written to the Q memory device (this is also processed by the above-mentioned image signal processing). (The clock signal is read out from the video signal written in the memory device using appropriate timing.)
@ (, 2)) From here, the bladder is read out sequentially according to the above read address signal, and if necessary, after performing some processing such as removing the sampling frequency component using a low-pass Oki waver, Extracted as an output video signal.Clock signal Q used for such image signal processingIn this case, if the write clock signal (1) at the time of recording the video signal is, for example, an in-house standard clock signal corresponding to the time axis of the input video signal, During the blanking period (recording and reproducing the video signal for this field)
This is preferably a high-speed clock signal with an appropriately compressed time axis.On the other hand, when reproducing a video signal, the relationship between the write clock signal and the read clock signal is reversed. The write clock signal (1) is the high-speed clock signal mentioned above, and the read clock signal (,
2) is the internal standard clock signal. Note that the above-mentioned write address counter 7 and read address counter r
The address clear circuit 91 generates an address clear signal for controlling the division of the front and rear parts of each field using the vertical synchronization signal as a reference. It shall be provided for writing and reading of video processing equipment.

Note that the compression/expansion of the time axis of the video signal described above (avoiding signal loss during the head flanking period) can be applied to such image signal processing alone, or it can be applied in combination with the delay of the video signal time axis described above. Therefore, it can be used with a relatively small time-axis compression/expansion ratio.

As is clear from the above perspective, the present invention is
To transmit broadband television signals such as high-definition television signals to a helical VTR, the rotational speed of the single rotary head is increased. For example, when the head blanking period is unavoidable when rotating at λ times the speed, it is possible to compare the lack of recording and playback damage that occurs during the image period using a delay device, memory device, etc. By using a simple circuit configuration, it is possible to easily and reliably process recording/reproduction image signals, and to reduce the number of rotations per second of a single recording/reproduction magnetic head to the number of fields per second of the video signal, Q. Even if you set any desired value beyond the normal revolutions per second, λ
Similar effects can be obtained in the same manner as described above when rotating at double speed. In other words, for example, when rotating at 3x speed, Q
This uses one delay device with a delay amount ↓3 times the length of the vertical blanking period, and moves the screen up and down.
The middle, bottom ◆ are divided into three parts and are shown in Figure 1 and Figure 4. Using a memory device, divide the screen into three categories: 1hi, medium, and ■.
Figures 3 and 3 are shown in Figures 1 and 2. can.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of an embodiment of recording/reproduction video signal processing according to the present invention, FIG. 2 is a block diagram showing an example of the configuration of a recording/reproduction video signal processing circuit according to the embodiment shown in FIG. Similarly, the second figure is a diagram showing another example of the aspect of recording and reproduction video signal processing according to the present invention, and the second figure is a block diagram showing an example of the configuration of the recording and reproduction video signal processing circuit according to the aspect shown in the third figure. / Counter, U/Switching controller, 3... Delay device, ≠ Switching device, J... Memory device, 6 Memory controller, 7 Write address counter 1. ! ′ Read address counter, counter
Address clear circuit. Patent applicant: Japan Broadcasting Corporation

Claims (1)

[Scope of Claims] 1. A ship for recording and reproducing the television signal by diagonally scanning a magnetic tape from a ship with a magnetic head rotating at a number of revolutions per second exceeding the number of fields per second of a television signal; dividing the field period of the television signal into a plurality of sections for a head blanking period that cannot touch the locus of rotation of the magnetic head;
changing the time axis of the television signal in at least one of the sections; At least during recording of the television signal reproduced from the magnetic tape (change the time axis of the television signal in the section where the time axis was not changed) A television signal recording and reproducing method characterized in that the plurality of sections in the television signal are made to be continuous.a In the recording and reproducing method according to claim 1, the time axis of the television signal is delayed. A television signal recorder system, characterized in that the time axis of the television signal is changed. A television signal recording and reproducing method characterized in that the time axis of the television signal is changed by compressing or expanding the time axis of the television signal.