JPS62274881A - Video signal reproducing device - Google Patents

Abstract

PURPOSE:To perform an extremely good variable speed reproduction without increasing the number of heads by providing a means for time base extending a video signal reproduced by a pair of rotating heads for one field unit. CONSTITUTION:At the time of the reproduction, a switch 21 is connected to an A side and the video signal outputted from a reproducing signal processing circuit 41 is outputted from a terminal 22 through a time base converter 20. When the instruction of a high speed search is outputted from an operating part 28, a switch 24 is connected to a C side. The outputs of detection circuits 25, 26 are compared in a comparator 27 and from which head a larger reproducing output is obtained is decided. The output of the comparator 27 controls a head change over switch 18 through the C side terminal of the switch 24. Thereby, the head used for the ordinary recording and reproducing can be used as a socalled double azimuth head and the extremely good high speed search can be performed without increasing the number of the heads.

Description

[Detailed Description of the Invention] 1. Detailed Description of the Invention <Industrial Application Field> The present invention relates to a video signal reproducing device, and in particular, a video signal reproducing device having mutually different azimuth angles, each recording one field worth of video signals. The present invention relates to a device for reproducing the video signal from a recording medium in which tracks are alternately formed.

<Prior Art> Conventionally, various video tape recorders (VTR) that are integrally equipped with a video camera have been proposed and implemented. In this type of so-called camera-integrated VTR, the biggest challenge is to reduce the weight and size of the main body.

On the other hand, a so-called rotating two-head helical scan type VTR is generally known for home use.

FIG. 3 is a diagram showing the arrangement of heads of this type of VTR. In FIG. 3, 1 is a magnetic tape and 2a.

2b is a tape guide for winding the tape 1 around the outer periphery of the rotating drum 3 over a range of 1800 or more angles.

HA and HB are rotating heads that are respectively attached to the rotating drum 3 with a phase difference of 180°, and have different azimuth angles. Head HA.

As is well known, the HB records and reproduces one field's worth of video signals during a 180° rotation.

In this type of VTR, the track length of one field's worth of video signals is predetermined by the standard, and accordingly, the diameter of the rotating drum 3 is necessarily determined. Therefore, the diameter of this drum cannot be made smaller, which hinders the reduction in size and weight of VTRs.

Therefore, the following VTRs have been proposed and put into practice as VTRs in which the drum diameter can be reduced. 41st! 1J is a diagram showing the head arrangement in a conventional VTR having a small diameter drum. In the figure, Ha and Hb are rotary heads having different azimuth angles, and rotate once during one field period of the video signal. Tape 1 is 3 to drum 4
It is wound over an angular range of 00° or more, and the rotating head Ha.

Each Hb records one field of video signals while rotating by 300°. That is, in one field period, a video camera (not shown) scans a screen with an aspect ratio of 9:10 (indicated by point fiY in FIG. 5), and scans a screen with an aspect ratio of 3 (indicated by a solid line X in FIG. : Head Ha, H within the 5/6 field period with the 4th screen as the valid screen.
Record with b.

The timing at the time of recording will be explained using the timing chart of FIG. 6. In the period indicated by T in the figure,
The video camera (not shown) has an aspect ratio of 9:10.
Scan the screen and select 3 consecutive images as shown in Figure 6(a).
A video signal consisting of 15 horizontal scans is obtained.

However, since the heads Ha and Hb actually trace 5/6 of the tape 1 within each field period, 262.5 horizontal scans are traced in Figure 6 (b).
) and record it on a magnetic tape as a video signal with an aspect ratio of 3:4. At this time, the heads Ha, H
Since the traces b are alternately traced on the magnetic tape, the VTR with the head arrangement shown in FIG. 4 can perform recording similar to the VTR with the head arrangement shown in FIG. 3. However, since it is necessary to provide a slight phase difference between the heads Ha and Hb at this time, it is necessary to appropriately delay the video signal of the first field or the second field.

If video signals are recorded as described above with the head arrangement as shown in FIG. 4, the drum diameter can be reduced to 315 mm of the VTR shown in FIG.

However, in a VTR having a head arrangement as shown in FIG. 4, it was not possible to reproduce recorded video signals. That is, even if the signals are reproduced from the tape 1 using the heads Ha and Hb of FIG. 4, a continuous reproduced video signal as shown in FIG. 6 cannot be obtained.

To solve this problem, Japanese Patent Laid-Open Publication No. 19372/1983 discloses a configuration that makes it possible to reproduce a video signal using a variable delay line. V disclosed in the publication
In TR, a reproduced video signal (having a reproduced RF waveform as shown in Fig. 6(b)) obtained in 5/6 field periods of one field period is expanded in time using a variable delay line and reproduced continuously. The purpose is to obtain a video signal.

<Problems to be Solved by the Invention> By the way, in general, stationary VTR models that can perform so-called still image playback, slow motion playback, and variable speed playback such as high-speed search have become commonplace in addition to normal playback. Ta. On the other hand, adding such functions to camera-integrated VTRs has not been done because of problems such as hindering weight reduction and increasing the number of heads.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a video signal reproducing device that can perform extremely good variable speed reproduction without increasing the number of heads or hindering weight reduction. .

<Means for Solving the Problems> With this object in mind, according to the present invention, tracks having different azimuth angles and each recording a video signal for one field are formed alternately. a pair of rotary heads having mutually different azimuth angles and arranged to trace each track in a period shorter than one field period; means for expanding the time axis of the video signal played back in units of one field;
Adopting a configuration comprising means for determining which of the pair of rotary heads can obtain a larger re-main output, and means for selectively outputting reproduction signals of the pair of rotary heads according to the determination means. are doing.

<Function> By configuring as described above, the pair of rotating heads can be used not only for normal playback, but also as a so-called double azimuth head for good variable speed playback, and extremely good performance without increasing the number of heads. Variable speed playback is now possible.

<Example> Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 shows a camera-integrated VTR as an embodiment of the present invention.
It is a figure showing a schematic structure of.

First, as described above, the operation when recording the imaging output of the imaging section 11 which reads out a video signal having 262.5 horizontal scanning lines in 5/6 of one field period will be described.

When a video signal as shown in FIG. 6) is read out from the imaging unit 11, the amplifier 12. The signal is supplied to the recording video signal processing circuit 16 via the input terminal of the switch 13, the R terminal of the switch 14, and the input terminal of the switch 15. In the recording signal processing circuit 16, as is well known, the luminance signal in the video signal is FM modulated, and the chroma signal is balanced modulated in its low range and frequency multiplexed. The video signal passed through the recording signal processing circuit 16 is supplied to the heads Ha and Hb via the bottom terminal of the switch 17 and the switch 18.

The heads Ha and Hb are arranged as shown in FIG. 4, and each rotates once in one field period, making 3000
It records one field of video signals while rotating. During recording, the switch 24 is connected to the N side by a control signal obtained from the system controller 29 in response to the operation of the operating section 28, and the switch 18 is connected to the N side by a control signal obtained from the system controller 29 in response to the operation of the operating section 28. P.G.
) can be switched.

At this time, the video signal output from the switch 14 is supplied to the time axis conversion circuit 20 and is time axis expanded. That is,
At this time, as shown in FIG. 2(a), the switch 14 outputs a video signal having a no-signal portion between each field, and this video signal is converted into a video signal of each field by the time axis conversion circuit 20. The time axis is expanded to 615, a normal video signal as shown in FIG. 2(b) is obtained, and the switch 21 is
The signal is output from the output terminal 22 via the A side of the . The output video signal is, for example, a CRT of an electronic viewfinder.

and television receivers.

Here, the detailed operation of the time axis conversion circuit 20 will be explained. The video signal output from the switch 14 is sent to the sync separation circuit 31. It is input to a low pass filter (LPF) 32. In the synchronization separation circuit 31, the synchronization signal in the video signal is separated, and a clock synchronized with this synchronization signal is generated in the generator 33. The frequency of this clock is selected to be such that the video signal can be sampled with sufficient resolution. For example, 4 fsa' and 3 fao' are selected. Here, fso' is the subcarrier frequency of the chroma signal in the video signal output from the switch 14, and is 615 times the subcarrier frequency (f a a) of the chroma signal of the television signal. .

The output clock of this clock generator 33 is used as a sampling signal of an analog-to-digital (A/D) converter 34 and is inputted to a memory control circuit 35 as a timing pulse. The memory control circuit 35 generates a write control pulse (5) for the memory 36 synchronized with the output of the frame clock generation Was and a read control pulse 0 for the frame memory 36 synchronized with the oscillation output of the reference oscillator 37. At this time, the frequency of the write control pulse station is 4 fsa'
If so, the frequency of the read control pulse 0 and the output signal of the reference oscillator is 4 faO.

In the frame memory 36, the video signal of the first field is written into the frame memory at the timing shown in FIG. 2(C), and read out at the timing shown in FIG. 2(d>).
The video signal of the field is written to another part at the timing shown in FIG. 2(e), and is successively outputted at the timing shown in FIG. 2(f).

The output signal of the frame memory 36 is digital-analog (
The signal is converted back to a normal analog video signal by the D/A converter 38 and output from the terminal 22 via the LPF 39. As a result, the video signal obtained by the imaging section 11 is supplied to the switch 18 in the signal form shown in FIG. or an external monitor.

Next, a case will be described in which a video signal input from an external source such as a tuner is recorded. 40 is a terminal to which an externally input video signal is input; at this time, switch 13.
15 and 21 are connected to the B side, respectively. The externally inputted video signal is output from the terminal 22 via the B side terminal of the switch 13, the R side terminal of the switch 14, and further the B side terminal of the switch 21. Further, the output signal of the switch 14 is subjected to time axis compression to 5/6 in units of one field by the time axis converter 20, and is supplied to the recording signal processing circuit 16 via the B side terminal of the switch 15. At this time, the time axis converter 20 inputs the video signal having the signal form shown in FIG. 2(1)) to the post-recording signal processing circuit 16 as the video signal having the signal form shown in FIG. 2(a). That is, the video signal supplied to the recording signal processing circuit 16 has the same signal format whether the video signal read out from the imaging section 11 is recorded or the video signal input from the outside is recorded. Therefore, recording on tape can be performed in the same way, and a normal video signal is output from the terminal 22 to a monitor or the like.

Here, time axis converter 2 when performing time axis compression to 5/6
The function of 0 will be explained. If the frequency of the clock output by the clock generator 33 is 4fsc, the frequency of the frame memory write control pulse (c) is also 4fsc.
It becomes so. At this time, the oscillation frequency of the reference oscillator 37 and the frequency of the read control pulse of the frame memory 36 are 4 feet'.

In this case, the first . The writing timing of the video signal of the second field is shown in Fig. 2 (
d) and (f), and the other bundle 1. The readout frequency of the second field is as shown in FIGS. 2(c) and 2(e), respectively.

Next, the operation during normal I playback will be explained. During playback, switches 14 and 17 are each connected to the P side. Also, during normal playback, the switch 24 is set to the system controller 2.
9 is connected to the N side. The video signals reproduced from heads Ha and Hb are switched by switch 18.PG. The signal is supplied to the reproduction signal processing circuit 41 via the P-side terminal of the switch 17, and is subjected to signal processing known in the art for VTRs. During playback, the switch 21 is connected to the A side, and the video signal output from the playback signal processing circuit 41 is output from the terminal 22 via the time axis converter 20. At this time, the time axis converter 20 performs the time axis expansion in step 615 described above, converts the video signal from the signal format shown in FIG. 2(a) to the signal format shown in FIG. get.

Finally, the operation during variable speed playback will be explained. When a still image reproduction is commanded from the operation unit 28 during normal reproduction as described above, the system controller 29 stops supplying the write control pulse W to the frame memory 36 of the memory control circuit 35. Thereafter, the capstan control circuit 30 stops the running of the magnetic tape. As a result, video signals of the same frame are successively outputted from the frame memory 36, making it possible to reproduce very good still images.

On the other hand, when a high-speed search command is issued from the operation unit 28, the system controller 29 causes the capstan control circuit 30 to run the tape at a speed several times higher than normal playback. The other switch 24 is connected to the C side. At this time, the reproduction signals reproduced from the heads Ha and Hb are respectively supplied to the F detection circuits 25.26.These detection circuits 25.2
The outputs of No. 6 are compared by a comparator 27, and it is determined from which head a larger reproduction output can be obtained.

The output of the comparator 27 controls the head changeover switch 18 via the C-side terminal of the switch 24.

As a result, a good reproduction signal can always be obtained from the switch 18. The output signal of this switch 18 is output as a reproduced video signal from the terminal 22 via the reproduced signal processing circuit 419 and the time axis conversion circuit 20, as in the above-described normal reproduction.

By configuring as described above, the head used for normal recording and reproduction can be used as a so-called double azimuth head, and extremely good high-speed searching can be performed without increasing the number of heads.

In the VTR of the above embodiment, it is determined whether the reproduction output of head Ha or head Hb is greater by comparing the reproduction RF levels of both heads. It is also possible to make a determination based on the phase relationship between the reproduced CTL and PG using the recorded l1wCTL signal. Furthermore, in a VTR that performs tracking control using the n4 frequency method, it is also possible to make the above determination using a tracking error signal obtained by this four frequency method.

<Effects of the Invention> As described above, according to the present invention, it is possible to obtain a video signal reproducing apparatus that can perform extremely good variable speed reproduction without increasing the number of heads.

[Brief explanation of the drawing]

Figure 1 shows a camera-integrated VTR as an embodiment of the present invention.
2 is a timing chart for explaining the recording and reproducing operation of the VTR shown in FIG. 1, and FIG. 3 is a diagram showing a rotating two-head helical scan type VTR
4 is a diagram showing the head arrangement in a conventional VTR having a small diameter drum. FIG. 5 is a diagram for explaining the scanning of the video camera in the VTR shown in FIG. 4. FIG. 6 is a timing chart during recording in the VTR of FIG. 4. 11 is an imaging unit, 16 is a recording signal processing circuit, 18 is a head selection switch, 20 is a time axis conversion circuit, 25.26 is R
27 is a comparator, 29 is a system controller, 41 is a reproduction signal processing circuit, and Ha and Hb are rotating heads.

Claims (1)

[Claims] A device for reproducing a video signal from a recording medium in which tracks having mutually different azimuth angles and in which one field worth of video signal is recorded are alternately formed, wherein each track is recorded for one field period. a pair of rotary heads having different azimuth angles and arranged to trace in a shorter period of time; means for time-axis expanding the video signal reproduced by the pair of rotary heads in units of one field; and the pair of rotary heads. A video signal reproducing apparatus comprising means for determining which of the two rotary heads can obtain a larger reproduction output, and means for selectively outputting reproduction signals of the pair of rotary heads according to the determination means.