JPH01871A - Video signal recording and playback method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for recording and reproducing video signals. In particular, it relates to a recording method that can increase the speed of high-speed retrieval on a VTR.

Conventional Techniques Various methods of recording video signals on a VTR have been studied.

The most common type is a rotating drum with magnetic heads attached to each other.
In a helical scan type magnetic recording/reproducing device, the rotary drum is mounted at an angle of 80 degrees, (18o+α) Cα is several tens of degrees at most), and the tape is wound around the tape to record video signals as diagonal tracks on the tape. Rotate at the frame frequency of the signal. Therefore, one field of video signal is recorded as one track. This situation is shown in FIG. In the figure, 1 is the tape, T is the tape running direction, and H
is the head running direction, and 2, 3, and 4.5 are tracks on which one field is each recorded.

In order to search a recorded tape at high speed while monitoring the reproduced image, it is necessary to reproduce the image from the recording track while running the tape at a speed sufficiently higher than the tape speed at the time of recording. At this time, the head traverses each track as shown in A to reproduce the data. Therefore, each part of the image of a plurality of fields is reproduced during one field period.

However, since the video signal of a certain part of the screen is recorded at a certain position in the tape width direction, a natural image can be reproduced even if images of a plurality of fields are combined.

In order to search faster, the tape running speed can be increased. However, in a typical VTR, the tape is wound around a large-diameter rotating drum and a stationary drum, so the frictional resistance between the stationary drum and the tape is particularly large, which limits the speed at which high-speed searches can be performed.

Problems to be Solved by the Invention As mentioned above, high-speed retrieval speed cannot be made much faster in rotary head type VTRs, so there remains a major dissatisfaction in terms of access time. The present invention aims to improve this drawback and provide a video signal recording method that enables a search speed several times that of conventional VTRs.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention reduces the frictional resistance by significantly reducing the angle at which the tape is wrapped around the drum during high-speed retrieval. 1
By recording information about the entire screen, it is possible to identify the reproduced screen.

Effects of the Invention With the above-described configuration, the present invention increases the tape running speed while maintaining the distinguishability of reproduced images during high-speed retrieval, thereby improving the retrieval speed.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 4. In this embodiment, the NTSC signal is rotated by a two-head VT.
This is applied when recording using R. FIG. 2 shows the tape loading state when recording and reproducing at normal speed. 6 is a rotating head drum, 7 is a cassette, 8 is a supply reel, 9 is a take-up reel, 1o is a guide roller, 1
1 is a capstan. The tape pulled out from the cassette is loaded in this way, wrapped around the drum 180 degrees, and recorded in the format shown in Figure 3.

The signal processing for creating the recording signal at this time will be explained with reference to FIG. In the figure, a is an input video signal, and the numbers are scanning line numbers. After this signal is digitized, it is temporarily stored in a field memory, and read out in the order of b in the next field period.

That is, this signal is obtained by reading out the odd-numbered scanning lines in the first half of the field and reading out the even-numbered scanning lines in the latter half of the field to restore the analog signal. This signal is FM modulated and recorded in the same way as a normal VTR. Therefore, in the recording format shown in FIG. 3, information for an entire screen is recorded in both the lower and upper halves of the track. Next, FIG. 1 shows the tape loading state during high-speed retrieval. The tape is wrapped around the drum at 90 degrees, with only the lower half of the recording track in contact with the head.

When the tape is run at high speed and played back in this state, the signal obtained is only from the bottom half of the tape, but since the signal processing described above is performed, all the odd lines are played back and the signal of the entire screen is obtained. . From this signal, signals of even-numbered scanning lines are generated by interpolation processing, stored in the field memory again, and then read out, thereby obtaining a signal close to a normal reproduction signal.

In this way, the tape winding angle during high-speed retrieval is made smaller than during normal playback.

Frictional resistance between drums can be reduced, tape speed can be increased, and search speed can be increased.

In order to further increase the retrieval speed, it is also possible to thin out one continuous scanning line from n consecutive scanning lines and record it in the lower nth of the number, so that the winding angle during high-speed reproduction is 180/n degrees.

In the above embodiments, the most common rotary two-head analog recording VTR has been explained, but the same applies to VTRs that expand the input signal on the time axis and divide it into multiple channels for analog recording, and VTRs that perform segment recording. The idea works.

Furthermore, in the case of digital VTRs that record video signals as digital signals, shuffling is generally performed to disperse and record the signals of the entire screen onto different parts of the tape in order to effectively correct errors. A similar effect can be obtained by performing recording signal processing such that the signal of the entire screen thinned out in a part in the width direction of the tape is recorded.

Effects of the Invention As detailed above, according to the present invention, the angle at which the tape is wrapped around the drum during high-speed retrieval is greatly reduced, and information for one entire screen is recorded within the range of the reduced winding angle. , it is possible to increase the tape running speed and improve the retrieval speed while maintaining the distinguishability of reproduced images during high-speed retrieval.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a tape loading state during high-speed search in an embodiment of the present invention; FIG. 2 is a plan view showing a tape loading state during recording or normal playback in an embodiment of the present invention; 3 is an explanatory diagram of a recording pattern on a tape according to an embodiment of the present invention, FIG. 4 is a simple explanatory diagram of recording signal processing according to an embodiment of the present invention, and FIG.
The figure is an explanatory diagram of a recording pattern on a tape in a conventional rotary two-head VTR. Name of agent: Patent attorney Toshio Nakao and 1 other box
3 Figure No. 41ffl +23-1---262263,! A4--Heeeeeee 52512(0)□ (pH) (:H) / l

Claims (1)

[Claims] The second range in which the head scans on the tape during high-speed playback is approximately half or less of the first range in which the head scans on the tape during recording, and the input signal is within the second range. A video signal recording and reproducing method for a video tape recorder, characterized in that information of the entire screen created by thinning is recorded.