JPS59205880A - Reproducer of video signal - Google Patents

Abstract

PURPOSE:To obtain a stable and continuous reproducing picture by providing plural heads reproducing simultaneously plural tracks to change over heads for a video signal reproduced simultaneously from each head at variable speed reproduction by means of counting the tape speed information and the timing. CONSTITUTION:In case of the 2-segment recording system, a rotary head Hp for reproduction only is provided in addition to a rotary head HRP for recording reproduction of a head device 5 and they are fitted to reproduce at the same time adjacent tracks. The adjacent tracks are scanned by the two heads at the same time at reproduction, and a video signal Sv(SRP, SP) recorded on each track is reproduced at the same time and fed to a switching circuit 23 through reproducing amplifiers 21, 22 respectively so as to attain switching thereby keeping the continuity of picture. A control signal CTL reproduced from a control head HC1 and a time code signal from a head HC2 for time code signal are fed to a switching circuit 33 and a changeover output of the switching circuit 23 is generated at a circuit 40 from any signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a VTR using a segment recording method suitable for application to business VTRs and the like.

BACKGROUND TECHNOLOGY AND PROBLEMS As shown in FIG.
'(2) is wound in Ω and helically scanned by one head H to record one field of video signal on one diagonal track.In a VTR, multiple heads are used for recording and playback. It is superior to VTR in terms of direct FM recording.

The reason is that when direct FM recording is performed using multiple heads, differences in the characteristics of each head appear as differences in differential gain, differential phase, or frequency characteristics, which can cause flicker and significantly degrade image quality. This is because there is. Since a VTR with one head configuration can obtain a high 87N, it is suitable for use in business VTRs and the like.

In order to make a one-head VTR more compact, the diameter of the rotating drum can be made smaller. At this time, if the rotational speed of the drum is made an integral multiple of the field frequency, a high relative speed can be obtained even with a small diameter drum, so that no deterioration of S/N occurs.

In order to make the VTR more compact, the diameter of the rotating drum is reduced, and the number of rotations of the drum is increased by n times (n is an integer).
When this is done, one field of video signal is recorded in segments.

For example, if the diameter of the rotating drum is the responsibility of the conventional method and the rotational frequency of the rotating drum is selected to be twice the field frequency, as shown in Figure 2, out of the video signal of one field,
Video signal A of the temple field in the first half is the first track 'I'
'ai l Tbl r..., and the video signal B of the temple field in the latter half is recorded on the next track Ta21 Tb2
,... are recorded. This is called the 2-segment recording force type.

By the way, when the segment recording method is adopted in order to downsize the VTR, it is necessary to reproduce continuous and stable images during slow and still playback in so-called variable speed playback mode, which plays back at a tape speed different from that during recording. It may not be possible to do so.

For example, in the case of still playback, the playback track pattern is as shown by the chain line in FIG. In such a case, by providing a dynamic tracking mechanism in the rotating magnetic head device, it is possible to obtain a reproduced video signal that has the sequentiality necessary to form one screen by providing still playback while omitting dynamic tracking. I can do it.

However, as shown in Figure 4, when the tape speed is different from that during playback, for example, when playing back at a high-speed tape speed of 4 times, the dynamic tracking mechanism no longer allows the video to have sequential image quality. Unable to reproduce signal.

Therefore, even in a one-head helical scan VTR, it is necessary to appropriately arrange an auxiliary head for reproduction and to appropriately switch the reproduction signals to convert them into continuous video signals. To do this, it is necessary to be able to distinguish between the multiple tracks that make up one field, but a common method for making such a distinction is to insert separate pilot signals into multiple tracks and use this signal during playback. In this method, the tracks are discriminated by extracting and separating the mother plot signals, and the reproduced signals are switched and controlled so that the sequential nature of the screen can be obtained.

However, this method requires several types of 79-lot signals and peripheral circuits for them, and the 4-lot signals may affect the video signal. Furthermore, in the case of high-speed reproduction mode, the reproduction frequencies of the pilot signals are different, which causes various problems such as the necessity of increasing the scale of the extraction circuit.

OBJECTS OF THE INVENTION Accordingly, the present invention provides a video tape recorder (VTR) using the segment recording method, in which a natural and stable reproduced image can be obtained without using any pilot signals in variable speed reproduction mode.

SUMMARY OF THE INVENTION Therefore, in the present invention, a plurality of heads are provided for simultaneously reproducing a plurality of tracks, and an image simultaneously reproduced by these heads during variable speed reproduction is provided without recording an identification signal of a video signal by field division. By counting the tape speed information and the timing of the head contacting the chip, a timing signal (head switching signal) that can be sequentially selected based on these signals is created to ensure image continuity. It was designed to do so.

By switching the reproduced video signal based on this timing signal, the above object is achieved.

Embodiment Next, an example of the present invention will be described as a two-segment recording type VTR.
The application case will be described in detail with reference to FIG. 5 and subsequent figures.

FIG. 5 shows an example of a rotary head device (5) which is a main part of the VTR according to the present invention. is the number of segments), therefore, in this example, one rotary head HP exclusively for reproduction is provided, and the mounting positions of these heads are selected so that adjacent tracks can be reproduced simultaneously. Therefore, the heads HRP and Hp may be configured as stepped heads as shown in FIG. 6, for example.

In addition, in the case of N segment recording, the same = rotating drum (
The mounting positions of the N heads are determined so that the N heads (including one recording/reproducing head HRP) mounted on the disk can simultaneously reproduce N tracks.

An example of recording and reproducing video signals using such a rotary head device (5) will be described with reference to FIG. 7 and subsequent figures.

FIG. 7 shows an example of the recording system a, in which the video signal Sv obtained at the terminal aυ is compressed by a predetermined amount in a time axis compressor α2 of the video signal sy in a fixed interval θr.

The amount of compression varies depending on the missing angle θ of the head HRP with respect to the chi f(2) (Fig. 5), but it is usually 5 to 10H.
is within the range of

An example of a compression form is shown in FIG. As the signal to be compressed, for example, a horizontal synchronizing pulse or a horizontal blanking signal existing during the horizontal blanking period, or a vertical synchronizing signal existing during the vertical blanking period is used. In the case of horizontal synchronizing pulses, the pulse width may be compressed. Therefore, according to this compression method, the video signal itself does not need to be compressed.

Note that (the old one was a generation circuit for obtaining a 30 Hz control signal CTL, and this control signal CTL was generated by Herad I (c 1
recorded. αD indicates a time code signal generator such as SMPTE, and the time code signal is generated by the head HC.
For example, as shown in Figure 11, tape (2)
recorded as a track along the length of the

The invention can be applied both with and without a time code signal. Therefore, in the following explanation, a case will be explained in which the control signal CTL is used.

FIG. 8 is a system diagram showing an example of the regeneration system (a).

During reproduction, the video signals Sv (SRP, Sp) recorded on the respective tracks are simultaneously reproduced by two heads HRP and Hp that simultaneously scan adjacent tracks.

The reproduced signals SRP and Sp are supplied to the switching circuit (c) through the reproduced amplifiers H and 74, respectively, and the reproduced signals SRP and Sp are switched so as to ensure the continuity of the image (detailed explanation). (described later).

The output of the switching circuit (24 is FMO regulator (2)
The M-demodulated and FM-demodulated video signal SV is TB (J5
), time axis correction including time axis expansion is performed, and a video signal Sv having a normal time axis is output.

Control signal CT reproduced by control head H61
The reproduced time code signals are sent to the reproduction amplifier 431),
It is supplied to the switching circuit C33) through G.

In this embodiment, the control signal CTL is selected and the switching pulse forming circuit f for the switching circuit (c)
40. In this forming circuit (40), switching between the reproduced video signals 8RP and Sp is performed so that image sequentiality is always obtained no matter what the tape speed is.

Now, in order to control the switching circuit (c) and obtain a normal screen, the speed of the tape (2) and the head HR must be adjusted.
It is necessary to know at what position P and HP enter into the tape, that is, the entry phase of the head into the tape. For example, FIG. 11 shows the scanning tracks and turns of the heads HRP and Hp when the tape is running at a high speed of 4 times, and the dashed line drawn diagonally indicates the scanning trajectory of the heads HRP and Hp.

If the head HRP enters the track where the first half field of the video signal is recorded, as shown in the figure, the head HR
By switching and controlling P and food, it is possible to always reproduce sequential images.

For example, instead of using this example, you can place the head H at the guard band.
In a case where the RP rushes in, the switching timings of the heads HRP and Hp must be reversed even if the same screen is to be formed.

Therefore, the switching pulse forming circuit (
40, along with the tape speed information, the head HR
Means are provided for detecting at what position P, Hp enters the track.

Furthermore, the timing at which heads are switched differs depending on the tape speed. For example, in a high-speed mode such as 4x speed, the head can be switched every 1/3 rotation of the drum as shown in Figure 11, but in 5x high-speed mode, the head can be switched every 1/4 rotation of the drum, as shown in Figure 11. There is a need. Therefore, it is necessary to also provide means for calculating the timing of such switching pulses.

FIG. 10 shows an example of a forming circuit (40) for forming a predetermined switching cell 7 by performing such processing.

In the figure, (40A) is a reference clock generation circuit, and the output of the control signal CTL supplied to the first terminal drives an N-times counter (the terminal 40A), which generates a predetermined number of pulses between multiple tracks. A reference clock having a frequency having a predetermined number of pulses is formed.The frequency having a predetermined number of pulses specifically refers to the reference clock frequency used for SMPTE time code, and this clock frequency is, for example, , 2.4 KHz, since the frequency of the control signal CTL is 30 Hz, the counter (4 counters may be multiplied by 80). This will reduce the number of clocks inserted in one frame. The number is 80, so exactly 20 clocks have been inserted between adjacent tracks.

(40B) is a counting circuit for obtaining phase data for the track when the head enters the tape (2), and the reference clock outputted by the counter (42) is supplied to the counter (43), and Terminal・, 4])K
The supplied control signal CTL is supplied as a reset pulse, and its data is supplied to the latch circuit (44JK). In the example, the pulse PG obtained by a pulse generator synchronized with the head HRP and Hp is used.Since the rotational position of the head and the pulse PG are always maintained in a certain relationship, the data of the counter +43 is used as a pulse. If latched by PG, phase data when the heads RRp and Hp enter the tape (2) will be obtained.

As shown in FIG. 11, the same tape (2
), the timing of the head HRP entering the channel f(2) is determined from when the control signal C'll''L is obtained. It can be obtained by counting the reference clock.The details of such head entry phase data will be described later.

(40C) is a tape speed data detection circuit.

This consists of a counter that operates using a clock multiplied by N and a latch circuit 14 that latches the count data.
It consists of (to) and. The pulse PG delayed by the delay circuit/i mark is supplied to the counter 147) as a reset signal, and the pulse PG itself supplied to the terminal (4) is supplied to the latch circuit 141 as a latch signal. be done.

Pulse PG can be obtained twice in one field, so this)
<? Since the number of clocks included in a cisPG interval differs depending on the tape speed, the tape speed can be determined from this number of clocks. Therefore, the latched count data becomes tape speed data.

The delay circuit (491) is a pulse PG and a counter (
After latching the count data of 47), the counter (
47).

This timing speed data and the above-mentioned head entry phase data are supplied to a switching pulse Ps forming section (40D). This forming part (40D) has first and second
o Performance X o ROM (PROM) ('4, (5
1) 7>E is set, the first FROM (50) is supplied with head entry phase data and tape speed data, and selects which of the heads HRP and Hp that entered the tape (2) first. selection pulse TP (Fig. 12G)
Then, a switching system PD (FIG. 12E) is formed that determines at what timing the first selected head is first switched.

The head entry phase data X can determine which position the head has entered based on this value. For example, when entering the center position of track A as shown in FIG.
= Q, when x-20, the vehicle enters the center of the next track B, and when x=10, the vehicle enters the center of the guard band between tracks A and B. Therefore, by this head individual phase data X, the first FR
In OM (51), the head HR entered the chi 7° (2)
A calculation is made to determine which one to select first, P or HP, and a selection pulse TP is output.

In this example, when X<1o, 3o<X<4o, the selection pulse PD is set to 'L' and the main head HRP is selected first.

The timing at which the first selected head HRP or Hp is first switched is determined by the head entry phase data
and tape speed.

For example, when the head HRP enters the center position of track A as shown in Figure 11, the first head switching timing is after the drum (1) has rotated 1/6, and the head HRP is in a different position from the one shown in the figure. When the drum (1) enters the center position, it is after the drum (1) has made one-third rotation or after it has made zero rotation. Therefore, w: 1C, 20-X) clock (at forward time) w7] < 20-x) clock (
After counting (during rewind), the first head switching timing occurs.

Therefore, in this example, the above data is stored in the first FROM, 5
@Yose is output and this is loaded into counter 5.

As the load timing, a delay system DL1 (FIG. 12D) in which the pulse PG is delayed by a predetermined time is used. 5T is a delay circuit for that purpose.

The data loaded into the counter (5) is counted up by the clock CK, and the carry i'? system obtained when 2O-X = 0 is the switching signal that switches the head first.
Mother sis PD and naru.

With this switching/9rus PD, the first 7th reset f (to)
is set, and its output pulse FFI (Fig. 12F)
and the selection pulse TP is the first exclusive sole or (4
), and the OR output EX1 (H in FIG. 12) and the 1/2 field discrimination pulse FF2 (C in FIG. 12), which will be described later, are supplied to the second exclusion pull or f5n, and the output EX1 in FIG. An OR output PS shown in is formed.

Since this OR output P3 is used as the head switching notification P3, in the example shown in FIG. 11, the head HRP is selected first, and when the drum (1) rotates 1/6, it is switched to the head HP.

Choice? cis Tl) and switching and cis PD are sparse)”H
Each time RPHp enters the tape (2), it is calculated and output from the first PROM f5I.

Following this, the head switching timing is determined by the second PROJ.
It is formed from the data of I).

Here, the automatic head switching timing at which the heads HRP and HP enter the chi f(2) differs depending on the timing f(2). For example, the head switching timing at quadruple speed is three times, Ps1 to Ps3, as shown in FIG. 11, which is every 1/3 rotation of the drum (1).

Since the distance traveled by the tape (2) by one rotation of the drum (1) is four tracks, the number of clocks is 4.times.20 clocks. Therefore, the head switching timing is determined by counting the number of clocks, and the general formula is as follows. That is, at n times speed, the head may be switched every w=,X 20 clocks (at forward time).

The second P, ROM5υ, is used for that purpose.
Data on head switching timing according to tape speed is calculated and output.

The data is supplied to the counter and OR circuit (loaded at the output timing of 6υ. Switching) When the mother system PD is obtained, data corresponding to the tape speed is loaded at that timing, and the count content of the counter becomes zero. Alternatively, the first flip-flop 1551 is controlled by the pulse C1 obtained when an overflow occurs.

In the case of Fig. 11, it is only necessary to switch the heads alternately every 1/3 rotation, so with Noxis c1, the output and system PF1
are alternately reversed. /f When Lucis 1 is obtained, this no'? Since the data for forming the next switching timing is loaded into the counter from the second PR, 0Ml5υ, in the system C1, the output pulse FF1 shown in FIG. 12F is obtained. As a result, the switching pulse Ps shown in FIG.
is formed.

In the latter half of the field, the field discrimination pulse FF2 is inverted, so that a switching mode shown in FIG. 12J is realized. According to this, it is clear that the reproduced video signal can be switched so as to maintain the sequentiality of the screen (see the dashed line (thick line) in FIG. 11).

When the head enters the center position of the band,
Since the selection pulse TP becomes H'' (K in Fig. 12), the head switching timing at this time is opposite to that described above (the first
2, see M).

In addition, in FIG. 10, the second free lag frog ((
(to) is the formation circuit of the discrimination/gusus FF2, which is controlled by the vertical drive system VD (FIG. 12A).

In the above embodiment, the present invention is applied to a two-segment system, but the number of segments is not limited.

As for the variable speed playback mode, 4x speed is just one example.

When using the SMPTB time code signal, the counter (4 is not necessary; in this case, the reproduced SMP
It is sufficient to directly add the TE time code M number to the subsequent counter (43).

As described in detail, according to the present invention, image sequentiality can be obtained without using a pilot signal, thereby eliminating all the disadvantages when using a pilot signal.

That is, there is no increase in the scale of peripheral rotation due to the use of several types of pilot signals, and there is no effect on the video signal. In addition, since there is no need for a pilot signal extraction circuit, the sound is natural in any variable speed playback mode.
A stable reproduced image can be obtained.

Therefore, the present invention is extremely suitable for application to business VTRs.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a rotary head device used to explain the present invention, FIGS. 2 to 4 are diagrams used to explain its operation, and FIG. 5 is a conceptual diagram of a rotary head device used in a VTR according to the present invention. A conceptual diagram showing an example, Fig. 6 is an explanatory diagram of a rotating head, Fig. 7 is a block diagram showing an example of a recording system, Fig. 8 is a Zoroku diagram showing an example of a reproducing system, and Fig. 9 is an explanation of its operation. FIG. 10 is a block diagram showing an example of a switching pulse forming circuit which is a main part of the present invention, and FIGS. 11 and 12 are diagrams for explaining the operation thereof. (40 is a switching pulse forming circuit, (40A) is a reference clock generation circuit, (40B) is a counting circuit, (40C)
) tri-chip mode detection circuit, (4oD) switching system forming section.

Claims (1)

[Claims] ■The video signal of the field is divided into multiple tracks and recorded on a chip. During playback, the tape is run at a speed different from that during recording, and the multiple heads corresponding to the multiple tracks are sequentially switched. A video signal reproducing device configured to reproduce a video signal includes a detection circuit that detects a shift speed based on a control signal recorded in the longitudinal direction of the tape, and a predetermined number of signals between the plurality of tracks during normal playback. of'? and a counting circuit that counts the reference clock based on the tape speed information, and uses the output of the counting circuit and the output of the tape speed detection circuit to A video signal reproducing device characterized in that a timing signal for switching heads is formed.