JPS63233686A - Tape recording/reproducing device for segment recording system - Google Patents

Abstract

PURPOSE:To prevent disturbance of pattern and crosstalk by controlling the running speed of a tape so that the deviation of horizontal synchronization between tracks is a half of a natural odd number and recording a television signal so that the television signal of the latter half of one field is retarded by 1/2 of the horizontal synchronizing period. CONSTITUTION:The tape running speed is controlled so that the deviation of horizontal synchronization between tracks formed at each other interval of the track formed on the tape is to be a half of a natural odd number at recording and the television signal at the latter half of one field is retarded by 1/2 of the horizontal synchronizing period and the result is recorded on the tape at recording. The first half of one field in the television signal is retarded by 1/2 of the horizontal synchronizing period at reproduction to match the phase with the horizontal synchronizing signal of the latter half of one field. Thus, the disturbance in the picture of joints of signals at the middle part of the reproduced pattern or pattern disturbance due to crosstalk from adjacent track is avoided.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention is to divide one field of a television signal interlaced so that one frame is made up of two fields into two and separate them into two fields. The present invention relates to an improvement of a segment recording type tape recording and reproducing apparatus that records on tracks.

(Prior Art) As is well known, for example, in home video tape recorders and the like, a color signal low frequency conversion recording method is generally widely adopted as the recording method. This color signal low frequency conversion recording method separates the television signal into a brightness signal and a color signal, frequency modulates the brightness signal (FM), converts the color signal to low frequency, and frequency multiplexes both. It is designed to record on the same track.

Here, FIG. 4 shows the frequency spectra of the low frequency conversion color signal and the luminance FM signal in the VHS system for NTSC signals. That is, as can be seen from Figure 4, the band of the luminance signal is about 2.7 MHz, and the band of the chrominance signal is also extremely narrow, about ±500 kHz at the -6 dB point, making it difficult to obtain high image quality. ing.

Here, there has conventionally been a direct FM recording method as a method that can reproduce the band of an input television signal as it is, and has been adopted, for example, in a 1-inch video tape recorder for broadcasting.

However, in this direct FM recording method, color subcarriers with high energy exist in the high frequency range, so moiré interference is large, making it impossible to set a high modulation index, and the performance of the tape head system is not suitable for professional use. Even if you use it as is for a home video tape recorder, which is much inferior to the
There is a problem that the S/N ratio deteriorates. In addition, the FM transmission band used is 14MHz in the high band method.
Because of the above, it is not suitable for home video tape recorders.

Therefore, in recent years, in order to obtain high-resolution and high-quality reproduced images, the relative speed between the tape and the head has been increased, and the rotational speed of the rotating drum has been increased to improve transmission characteristics. A segment recording method for recording and reproducing television signals has been considered. According to this method, for example, at the standard tape running speed (SP mode) of the current VHS system (horizontal synchronization deviation number α11-1.5), if the rotation speed of the rotating drum is doubled to 3,600 revolutions/rotation type. The C/N ratio of the tape playback signal is improved by more than 6 dB with the same tape head carrier signal, and it becomes possible to record and playback using the direct FM recording method as a signal format that provides high resolution.

However, in this segment recording method, since there is a switching point of the reproduction signal obtained from the head in the center of the reproduction screen, problems arise in that image disturbance and skew distortion occur. That is, NTSC signals (525 lines,
59.94Hz), as shown in FIG. 5, the AI and Bl between adjacent tracks.

A2. B2. For A3..., there is a deviation in the H alignment of 0,125H (H is one horizontal synchronization period), and for adjacent tracks (Al, A2), (Bl, B2)..., there is a deviation of 0.25H.
A deviation occurs in the H alignment.

For this reason, for example, during special playback such as fast forward playback or rewind playback, when the head straddles the track, 0.25H
skew distortion occurs, making the screen unsightly. Further, due to crosstalk from adjacent tracks, the horizontal synchronization portion, which causes particularly large disturbances, enters the visible portion of the screen, resulting in a problem that image quality is impaired.

(Problems to be Solved by the Invention) As described above, in the conventional segment recording method in which the number of rotations of the rotating drum is doubled, image disturbances occur at the signal joint in the center of the playback screen. There are problems such as screen interference due to crosstalk from adjacent tracks, especially crosstalk from horizontal synchronizing signals. Furthermore, during special playback, skew distortion occurs due to deviations in the H alignment of adjacent tracks, resulting in a problem that the screen is distorted.

Therefore, this invention was made in consideration of the above circumstances.
Without sacrificing the advantages of the segment recording method, it is possible to eliminate image disturbances at signal joints in the center of the playback screen and screen disturbances due to crosstalk from adjacent tracks, and also to eliminate image disturbances during special playback. It is an object of the present invention to provide an extremely good segment recording type tape recording/reproducing apparatus which can solve the problems.

[Structure of the Invention] (Means for Solving the Problems) That is, the segment recording type tape recording and reproducing apparatus according to the present invention records a television signal that is interlaced so that two fields constitute one frame. With one rotation of the rotating drum equipped with a head, one field of television signals is divided into the first half and the second half.
It is intended for recording on tape with a track.

During recording, the running speed of the tape is controlled so that the amount of horizontal synchronization deviation between every other track formed on the tape is 1/2 of an odd natural number. , the television signal in the latter half of one field is recorded on tape with a delay of 1/2 of one horizontal synchronization period.

Also, during playback, a pair of heads traces the corresponding tracks on the tape, and out of the television signal obtained, the first half of one field is converted into 1/2 of one horizontal synchronization period.
The signal is delayed by 100 seconds to match the phase with the horizontal synchronizing signal in the latter half of one field.

(Function) According to the above configuration, it is possible to record a television signal on a tape by matching the H alignment of adjacent tracks, without sacrificing the advantages of the segment recording method.
It is possible to eliminate image disturbances at signal joints in the center of the playback screen, screen disturbances due to crosstalk from adjacent tracks, and image disturbances during special playback.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. In FIG. 1, the television signal supplied to the input terminal 11 is routed through the switch circuit 12 and inputted as it is to the recording signal processing circuit 13.
The signal is delayed by 1/2 of one horizontal synchronization period by the H delay circuit 14 and is selectively input to the recording signal processing circuit 3. The switching operation of the switch circuit 12 is performed by a switching pulse output from a switching pulse generating circuit 15 driven based on a television signal.

The television signal, which has been subjected to predetermined processing for, for example, direct FM recording, by the recording signal processing circuit 13 is sent to the head 1B (actually 180' facing the circumferential side of a rotating drum (not shown)). The television signal is recorded onto the tape 17 using the segment recording method via the television signal (two of which are provided), and the television signal is recorded here.

The above recording operation will be specifically explained as follows.

In other words, in this segment recording method, as shown in Figure 2, one field of an interlaced television signal is divided into two and recorded on two tracks so that two fields make up one frame. One frame (525 tracks) is composed of four tracks.

In this case, between adjacent tracks (AI).

A2), (Bl, B2)... The number of horizontal synchronization deviations is 1/2 of the odd natural number (1.5H in Figure 2)
The running speed of the tape 1γ is controlled so that Then, as is clear from FIG.
, A2), (Bl, B2) The H alignments of the rivers are combined. In this case, the running speed of the tape 17 is
It is set to twice the standard tape running speed (SP mode).

Here, if only the running speed of the tape I7 is controlled as described above, as shown in FIG.
Bl, A2. The horizontal synchronization of B2... is off by 0.5H. For this reason, truck AI.

A2. The television signal to be recorded in A3..., that is, the television signal in the first half of the L field, is directly transferred to the switch circuit 12. Recording signal processing circuit 13 and head 18
are recorded on the tape 17 via tracks B1, B2, etc.
・The television signal to be recorded, that is, the television signal in the second half of one field, is
After being delayed by 1/2 of the horizontal synchronization period, switch circuit 12. The switching operation of the switch circuit 12 is controlled so as to record on the tape 17 via the recording signal processing circuit I3 and the head 1B.

Then, as shown in FIG. 3, the AI and B between adjacent tracks are
l, A2. The H sequences of B2... are all combined.

Next, tape playback will be explained. That is, the reproduced signal obtained by tracing the track of the tape 17 by the head 1G is supplied to the reproduced signal processing circuit 1B and subjected to predetermined processing for reproduction. and a path delayed by 1/2 of one horizontal synchronization period by the 0.5H delay circuit 21 and guided to the output terminal 20. This switching operation of the switch circuit 19 is performed by a switching pulse output from a switching pulse generation circuit 23 which is driven based on the output of the head position detection circuit 22.

Here, the head position detection circuit 22 generates a signal indicating which head 1G is currently tracing the tape 17 among the two heads 16 supported by the rotating drum. Then, the switching pulse generation circuit 2
3, one head 1B is located on track Al, A2 . A3...
The reproduced signal obtained by tracing, that is, the television signal of the first half of one field, is delayed by 1/2 of one horizontal synchronization period in the 0.5H delay circuit 21 and guided to the output terminal 20, and then sent to the other head 16. The switch circuit 19 is operated so that the reproduced signal obtained by tracing the tracks B1, B2, .

Therefore, tracks Al, A2. A reproduction signal obtained by tracing A3... and track Bl.

The playback signal obtained by tracing B2... is horizontally synchronized and taken out to the output terminal 20, and is then used for image display, causing skew distortion at the joint in the center of the screen. Good image display is performed without any problems.

In addition, as shown in FIG. 3, AI and B between adjacent tracks
1. A2. Since all the H sequences of B2, . In addition, between adjacent tracks (AI).

Since the H sequences of A2), (Bl, B2)... are matched, the horizontal synchronization phase when the head 1B crosses the track is matched during special playback such as fast-forward playback or rewind playback, so this point However, good image display without skew distortion can be achieved.

Here, the tracks At, A2 . The playback signal obtained by tracing A3... and the track B output from the playback signal processing circuit 18
l, B2... with the reproduced signal obtained by tracing,
The horizontal synchronization signal phase detection circuit 2 detects the phase difference of the horizontal synchronization signal.
4, the detection result is held in the sample and hold circuit 25 at the timing of switching of the switch circuit (2) 9, and based on this hold value, 0.
By controlling the delay port of the 5H delay circuit 21, it is possible to eliminate skew distortion at the joint at the center of the screen caused by variations in the speed of the tape 17, errors in the attachment of the head 1G, and the like.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without departing from the gist thereof.

[Effects of the Invention] Accordingly, as described in detail above, according to the present invention, image disturbance at the joint portion of signals in the center of the playback screen and crosstalk from adjacent tracks can be prevented without sacrificing the advantages of the segment recording method. It is possible to provide an extremely good segment recording type tape recording and reproducing apparatus that can eliminate screen interference caused by talk and can also eliminate image disturbance during special playback.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a segment recording type tape recording/reproducing apparatus according to the present invention, and FIGS. 2 and 3 are for explaining the operation of the same embodiment, respectively. FIG. 4 is a diagram showing the frequency spectrum of a luminance signal and a color signal, and FIG. 5 is a diagram showing a track pattern recorded on a tape by the conventional segment recording method. 11... Input terminal, 12... Switch circuit, 13.
...recording signal processing circuit, 14...0.5H delay circuit,
I5...Switching pulse generation circuit, 1B...Head, 1
7... Tape, 18... Playback signal processing circuit, 19.
...Switch circuit, 2o...Output terminal, 21...0
．． 5H delay circuit, 22...head position detection circuit, 23
. . . switching pulse generation circuit, 24 . . . horizontal synchronization phase detection circuit, 25 . . . sample hold circuit. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] One rotation of a rotating drum equipped with a pair of heads divides the interlaced television signal so that one frame is made up of two fields into two tracks. In a tape recording and reproducing apparatus of a segment recording method for recording on a tape, the amount of horizontal synchronization deviation between every other track formed on the tape is 1/2 of an odd natural number. recording means for controlling the running speed of the tape and recording the television signal in the second half of one field on the tape with a delay of 1/2 of one horizontal synchronization period; reproducing means for delaying the first half of one field by 1/2 of one horizontal synchronization period of a television signal obtained by tracing a track to match the phase with the horizontal synchronization signal of the second half of one field; A segment recording type tape recording and reproducing device, comprising: