JPH01184749A - Rotary head type magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute reproduction by always the same rotary magnetic head as that of recording and to obtain an efficient reproduced video signal free from horizontal oscillation by setting up an overlapped recording variable based upon a specific rotary magnetic head differently from an overlapped recording variable based upon other rotary magnetic heads. CONSTITUTION:In case of executing overlapped recording by four rotary magnetic heads 2a-2d, the overlapped recording variable alpha of at least one rotary magnetic head 2d is set up differently from the overlapped recording variable alpha+DELTAalpha of other rotary magnetic heads. At the time of reproducing, the lengths of recording tracks scanned by the rotary magnetic heads 2a-2d and the length of a recording track scanned by the other rotary magnetic heads are discriminated, and when the length of the track is different from that of the other tracks, tracking is shifted by every 2 tracks. Thereby, the rotary magnetic heads 2a-2d at the time of recording and reproducing are the same or not is discriminated, and in case of using different heads, tracking is shifted by every 2 tracks and the magnetic heads are controlled so as to be always the same at the time of recording and reproducing. Consequently, a picture generating no horizontal rocking due to the variation of a time axis can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rotary head type magnetic recording system that uses four rotating magnetic heads and winds a magnetic tape around a drum for a total of 2,706 times to perform recording and reproduction. Playback device (hereinafter referred to as VTR)
Specifically, it relates to a VTR in which signals are reproduced using the same rotating magnetic head used for signal recording.

[Prior Art] In contrast to the conventional VTR, which uses two rotating magnetic heads and records and plays by wrapping a magnetic tape 180 inches around a drum, we developed a VTR that uses four rotating magnetic heads to make the device smaller and lighter. Using a magnetic head, the diameter of the drum is reduced to 2/3, the rotational speed of the drum is reduced to 3/2, and the magnetic tape is wound around the drum at 270 degrees to achieve the same tape format as a conventional VTR for recording and playback. A VTR that does this has been put into practical use.

FIG. 8 shows the relationship between the rotating magnetic head, drum, and magnetic tape of this VTR. In the same figure, (1) is a drum, (
2a), (2b), (2c), (2d) (hereinafter, (
2)) are CHI, CH2, CH3°CH4 rotating magnetic heads arranged at 90" intervals, and their magnetic gaps are the same azimuth for CHl and CH3°CH2 and CH4, respectively, and CHI and CH2 are opposite. (3) is a magnetic tape that is wound around the drum (1) over an angular range of just over 270 degrees, which is the effective winding angle of 270 @ plus a slight angle for overlapping recording. The drum (1) has a period of 45 r, which is 3/4 of the field frequency of the video signal, 60 Hz.
ps, and every time this drum (1) rotates 3/4 of a turn, that is, more than 270 degrees, an L field of video signals is recorded on one track.

Figure 8 shows the CHI head at the tape entrance.
From this point on, recording by the CDI head begins, l/6
After 0 seconds, drum 1 rotates 270" and the CHI head moves to the tape exit, where the L field video signal is recorded on one track. At this time, the CH2 head reaches the tape entrance, and the recording by this CH2 head starts. It begins.

In this way, CHI→CH2→CH3→CH4→CH
The rotating magnetic head is switched in the order of I..., and a recording track is formed.

FIG. 9 is a block diagram showing the structure of a recording/reproducing head switching and signal processing circuit. In the same figure, (4a)
, (4b), (4c), (4d) (hereinafter abbreviated as (4)) are changeover switches for switching between recording and playback, (5
) is the switching signal input terminal for switching this switch (4), and (6a), (6b), (6c), and (6d) (hereinafter abbreviated as (6)) are the terminals for recording to the rotating magnetic head (2). Selector switch for connecting IIfr signals, (7a),
(7b), (7c), and (7d) (hereinafter abbreviated as (7)) are control signal input terminals that control the changeover switch (6), and (8) is a recording signal that is supplied to the rotating magnetic head (2). (9) is a recording signal processing circuit that converts the video signal into a recording signal; (10a), (1)
0b), (10c), (10d) (hereinafter, (10)
(abbreviated as ) are recording signal amplifiers (Ila') and (I
lb), (llc) (hereinafter abbreviated as (11))
(12a) and (12b) (hereinafter abbreviated as (12)) are control signal input terminals that control the selection switch (11); (13) is a reproduction signal processing circuit that processes the reproduction signal.

FIG. 1O is a block diagram showing the configuration of a drum and capstan rotation phase control circuit. In the same figure, (2
0) is the drum FG input terminal that represents the rotational speed of the drum, (
21) is the FF30 input terminal that represents the rotational phase of the drum;
(22) is the reference signal input terminal for the drum and capstan, (23) is the capstan FG input terminal that indicates the rotational speed of the capstan, (24) is the playback control signal input terminal, and (25) is the input terminal for the drum from the tram FG. (26) is a phase comparison circuit that compares the phase of the FF30 and the reference signal; (27) is a speed comparison circuit that compares the rotation speed of the capstan from the capstan FG; (28) is a speed comparison circuit that compares the rotation speed of the capstan. A frequency dividing circuit that divides the frequency of the capstan FG, (29) a changeover switch that switches between a signal obtained by dividing the frequency of the capstan FG and a reproduction control signal, and (30) a signal obtained by dividing the frequency of the capstan FG during recording.

and a phase comparison circuit that compares the phases of the reproduction control signal and the reference signal during reproduction, (31) an addition circuit that adds the output of the drum speed comparison circuit (25) and the output of the phase comparison circuit (26), (32) (33) and (34) are drive circuits that drive the motors. (35) is a drum motor. 36) is a capstan motor.

FIG. 11 (A) to (G) show timing charts during recording, and FIG. 11 (H) to (L) show timing charts during reproduction. (A) in Figure 11 is a vertical synchronization signal extracted from a recorded video signal, and (CB) in the same figure is a vertical synchronization signal extracted from a recorded video signal.
This signal is frequency-divided by /2 and serves as a reference signal for the drum and capstan as well as a recording control signal (hereinafter referred to as recording CTL signal). (C) and (J) in the same figure are control signals FF30 input to the control signal input terminal (12a).
, same figure (D), (E).

(F) and (G) are control signal input terminals (7), respectively.
Control signals input to H-SWI, H-SW2, H-S
W3, H-3W4, (H) in the figure is the reference signal for the drum and capstan during playback, (1) is the playback control signal, and (K) is input to the control signal input terminal (12b). The control signal FF15 (L) in the figure shows switching of the rotating magnetic head selected during reproduction.

Next, the operation of the above configuration will be explained.

During recording, the changeover switch (4) is switched to the REC side by a changeover signal input from the changeover signal input terminal (5). The changeover switch (6) receives the control signal H-3WI input from the control signal input terminal (7).

H-3W2. H-3W3. H-SW4 is connected for a period of high level, and FIGS. 11(D), (E), (F), and (G)
CHI for each l field as shown in .

- Recording signals are supplied in the order of CH2, CH3, and CH4. However, in order to perform overlap recording, control signals H-3WI, H-3W2 . H-SW3. The high level period of H-SW4 is slightly longer than one field.

On the other hand, during playback, the changeover switch (4) is switched to the PB side by a changeover signal input from the changeover signal input terminal (5), and the signals reproduced from the rotating magnetic head (2) are sent to the playback signal amplifier ( IO). The changeover switch (11) receives the control signal FF30 input from the control signal input terminal (12) shown in FIGS. 11(J) and (K).
．． Switched by FF15, CH in one field period
Regenerative amplifier (10) in the order of I, CH2, CH3゜CH4
The output of is switched and input to the reproduction signal processing circuit (13).

Next, the operation of the rotational phase control circuit for the drum and capstan will be explained.

During recording, the input terminal (21) in FIG.

The phase comparison circuit (26) compares the phase difference between the FF30 and the reference signal input from the input terminal (22).
The tram FG input from the speed comparison circuit (25)
), and the output of the phase comparator circuit (26) and the output of the speed comparator circuit (25) are added together in the adder circuit (31), and the drive circuit (33) of the tram motor (35) is controlled by the output of the FF30. As shown in FIGS. 11(B) and 11(C), the phase relationship between the FF 30 and the reference signal is controlled so that the rising edge of the FF 30 is 6.5H ahead of the rising edge of the reference signal. Also, the capstan FG input from the input terminal (23)
are compared by the speed comparison circuit (27), and the frequency of the capstan FG is divided by the frequency division circuit (28), and the changeover switch (
29) to the phase comparator circuit (30), and the phase comparator circuit (30) compares the phase difference between the frequency-divided signal of the capstan FG and the reference signal input from the input terminal (23). The output of the comparator circuit (27) and the phase comparator circuit (3
The capstan motor (36) rotates at a predetermined speed by controlling the drive circuit (34) of the capstan motor (36) with the output obtained by adding the outputs of travel at a speed of In addition,
The reference signal shown in FIG. 11(B) is recorded on the magnetic tape as a recording control signal.

During playback, the rotational phase of the drum motor (35) is controlled in the same way as during recording, and as shown in FIGS.
controlled in an advanced state. In addition, the playback control signal input from the input terminal (24) is changed to the selector switch (29).
) to the phase comparator circuit (30), and the input terminal (2
The phase difference with the reference signal input from 2) is compared with the phase comparison circuit (30), and the phase comparison circuit (30)
) and the output of the speed comparison circuit (27) to the Jo arithmetic circuit (
The capstan motor (36) is
), the running of the magnetic tape is controlled so that the rising edge of the reference signal coincides with the positive pulse of the reproduction control signal, as shown in FIG. 11 (H) and (1). controlled.

In this way, the video signal is reproduced by accurately scanning the recording track with the rotating magnetic head having the same azimuth as during recording. For example, a track recorded using a CHI head can be recorded using a CHI head or a C with the same azimuth as the CHI head.
Play with H3 head. The probability is 1/2 whether the rotating magnetic head is the same during recording and during reproduction, or when it is different. If there is a fluctuation in the rotational speed of the drum that is synchronized with the rotational period of the drum, if the rotating magnetic heads are the same during recording and playback, the phases of the fluctuations in the drum rotational speed during recording and playback will match and cancel out. If the rotating magnetic heads used for recording and playback are different, the phases of the rotational speed fluctuations of the drums during recording and playback will match and will not cancel each other out, so there is no problem. wake up

[Problems to be Solved by the Invention] Conventional VTRs are configured as described above, so the rotating magnetic head during recording and reproducing is not always the same, and the rotation during recording and reproducing is not always the same. When the magnetic heads are different, there is a problem in that the reproduced video signal varies in the time axis, causing horizontal shaking on the monitor screen.

This invention was made to solve the above-mentioned problems, and in the case of self-recording, reproduction is always performed using the same rotating magnetic head as used during recording, thereby obtaining a screen that does not cause lateral shaking due to time axis fluctuations. The purpose is to provide a VTR that can do a lot of things.

[Means for Solving the Problems] A VTR according to the present invention, when performing overlap recording with four rotating magnetic heads, sets the overlap recording amount of at least one rotating magnetic head to the overlap recording amount of the other rotating magnetic heads. The length of the recording track being scanned by the rotary magnetic head during reproduction is determined from the length of the track recorded by another rotary magnetic head, and if the lengths of the tracks are different based on the determination result,
It is characterized in that the tracking is shifted by two tracks.

[Function] According to the present invention, the length of the recording track by one rotary magnetic head is made different from the length of the recording track by the other rotary magnetic heads during recording, and the recording is performed depending on the presence or absence of a reproduction signal at a predetermined timing during reproduction. By determining the length of the track, it is determined whether the rotating magnetic head during recording and playback is the same, and if they are different, the tracking is shifted by two tracks, so that the rotating magnetic head during recording and playback is always the same. controlled so that

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram of a VTR recording/reproducing head switching and signal processing circuit according to an embodiment of the present invention.
In this figure, since the configuration is the same as that of the conventional VTR shown in FIG. 9 except for the points explained below, the same reference numerals are given and the explanation thereof will be omitted.

In FIG. 1, the output of the regenerative amplifier (10d) is input to the changeover switch (llb), and is also input to the newly provided regenerative signal detection circuit (40), and the output of this regenerative signal detection circuit (40) is input to a latch circuit (41), latched by a latch pulse input from an input terminal (42), and output to a discrimination signal output terminal (43).

FIG. 2 is a block diagram showing a specific example of the configuration of the reproduced signal detection circuit (40), in which (44)
is an input terminal, (45) is a detection circuit that performs envelope detection of the reproduced signal, (46) is a comparator that compares the output of this detection circuit (45) with the potential of the DC power supply (47),
(48) is an output terminal.

In addition, in FIG. 1, the overlap amount of the control signal H-SW4 inputted from the control signal input terminal (7d) or the control signal H-SW4 inputted from the control signal input terminals (7a), (7b), (7c) 3WI, H-3W2. H-3
It is larger than the overlap amount of W3.

FIG. 3 is a block diagram of the drum and capstan rotational phase control circuit of this embodiment, and in this figure, the conventional VT shown in FIG.
Since it has the same configuration as R, the same reference numerals are given and the explanation thereof will be omitted.

In FIG. 3, the output of the adder circuit (32) is not directly input to the drive circuit (34), but a newly provided adder circuit (
50), added to the output of the capstan acceleration circuit (51), and then input to the drive circuit (34).

Next, the operation of the above configuration will be explained.

The operation during recording is the same as the conventional example except for one point described below.

That is, as shown in the timing chart shown in FIG. 4, H-3WI, H-SW2. Both sides of H-3W3 and H
The amount of overlap on the front side of -SW4 is α, whereas the amount of overlap on the rear side of H-3W4 is α+Δα. FIG. 5 shows the state of the recording track at this time. Since the amount of overlap of H-3W4 with the CH4 head is larger than the others, the recording track by the CH4 head is longer than the other recording tracks.

FIGS. 6 and 7 show timing charts during reproduction. Figure 6 shows the track CH4 recorded with the CH4 head.
This is the case when the head is used for reproduction, that is, the same rotating magnetic head is used during recording and reproduction. Figure 7 shows the case when a track recorded by the CH2 head is reproduced by the CH4 head, that is, during recording and reproduction. This is the case when the rotating magnetic heads are different.

In FIGS. 6 and 7, (A) is the FF 30, (B) is the FF 15, and (C) is the latch pulse input from the input terminal (42), which is a pulse delayed by 7 from the rising edge of the FF 15. This delay time T is set so that α<q<α+Δα with respect to the overlap amount α during recording. (D) is the output of the playback signal amplifier (10d) that amplified the playback output of the CH4 head, and (E) is the output of the playback signal detection circuit (40) that detected the presence or absence of the output of the playback signal amplifier (10d). be.

As shown in FIG. 6, if the same rotating magnetic head is used for recording and reproduction, the CH4 head will reproduce the track recorded with α+Δα overlap by the CH4 head.
When the latch pulse rises, the reproduction signal amplifier (LOD)
) is present, and the output of the reproduced signal detection circuit (40) is at the old GH level. This old gh level is the latch circuit (4
1) and output to the discrimination signal output terminal (43).

On the other hand, as shown in Figure 7, if the rotating magnetic heads used during recording and playback are different, the CH2 head will play back the track recorded with an overlap of α by the amount of α, so the timing when the latch pulse rises. and playback signal amplifier (1
0d), and the output of the reproduced signal detection circuit (40) is at a low level. This Low level is latched by the latch circuit (41) and output to the discrimination signal output terminal (43).

In Fig. 3, when the discrimination signal output input to the terminal (43) is at the old gh level, the capstan acceleration circuit (51)
The output of the adder circuit (32) is inputted directly to the drive circuit (34) through the adder circuit (50), and the tape running is controlled in the same way as in the conventional example shown in FIG. . When the discrimination signal output input to the terminal (43) is at Low level, the capstan accelerator circuit (51) outputs a pulse of the old gh level with a constant pulse width, and the adder circuit (50) outputs a pulse of the old gh level. The signal is added to the output of , and is input to the drive circuit (34) to accelerate tape running and cause tracking to momentarily deviate.

Hi output from this capstan acceleration circuit (5I)
The pulse width of the gh level is set so that tape running is accelerated and tracking advances by two tracks. Therefore, the state in which the rotary magnetic heads are different during recording and reproduction changes to the state in which the rotary magnetic heads are the same.

In addition, in the above embodiment, the overlap amount on the rear side of CH4 is made larger than the others, or the overlap amount on the front side may be made larger or smaller than the others. Alternatively, the detection accuracy may be improved by making two or more overlap amounts different from each other.

Furthermore, in the above embodiment, the capstan is accelerated when the rotating magnetic heads are different during recording and reproducing, but the capstan may be decelerated or the drum may be accelerated or decelerated. .

Furthermore, in the above embodiment, the period of the reference signal for the drum and capstan was kept unchanged for two fields;
When the rotating magnetic heads are different during recording and reproducing, the period of the drum or capstan reference signal may be changed to four fields, so that the tracking is shifted by two tracks.

[Effects of the Invention] As described above, according to the present invention, the overlap recording amount by a specific rotating magnetic head is made different from the overlap recording amount by other rotating magnetic heads, and the Since it is possible to identify the rotating magnetic head during recording and to always perform playback using the same rotating magnetic head as during recording, even if there is a rotational speed fluctuation synchronized with the rotation period of the drum, time axis fluctuations can be eliminated and lateral It is possible to obtain a good reproduced video signal without shaking.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a VTR recording/reproducing head switching and signal processing circuit according to an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a reproduced signal detection circuit in this embodiment, and FIG. 3 is a block diagram of this circuit. A block diagram of a VTR and a capstan rotation phase control circuit according to an embodiment of the invention, FIGS. 4, 86, and 7 are timing charts for explaining the operation of this embodiment, and FIG. 5 is a diagram of this embodiment. Figure 8 shows a recording pattern on a magnetic tape in which a magnetic tape is placed on a drum using four conventional rotating magnetic heads.
Figure 9 is a block diagram showing the configuration of the magnetic head switching and signal processing circuit of a conventional VTR; FIG. 11, which is a block diagram of a rotational phase control circuit for the drum and capstan of a VTR, is a timing chart for explaining the operation of a conventional example. (2a), (2b), (2c), (2d) ---Rotating magnetic head 1, (4a), (4b), (4c), (4d
), (6a), (6b), (6c), (6d), (
lla), (llb), (llc), (29) = changeover switch, (9) ---recording signal processing circuit, CIDa)
, (10b>, (lDc), CIDd) - Reproduction signal amplifier, (13)... Reproduction signal processing circuit, (25), (
27) Speed comparison circuit, (25), (30)...
Phase comparator circuit, (31), (32), (50)...
- Addition circuit, (40)...Reproduction signal detection circuit, (41
)...Latch circuit, (51)...Capstan acceleration circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] (1) In a rotating head type magnetic recording and reproducing device that uses four rotating magnetic heads and records and plays by wrapping a magnetic tape around a drum at over 270 degrees, there is no overflow caused by one rotating magnetic head during recording. Means for making the amount of lap recording different from the amount of overlap recording by other rotating magnetic heads, and determining the length of the recording track scanned by one rotating magnetic head during reproduction by the recording track recorded by that rotating magnetic head. A rotary head type magnetic recording and reproducing apparatus characterized by comprising: a determining means for comparing and determining the length of the recording track; and a controlling means for shifting the tracking by two tracks if the length of the recording track differs in the determination result by the determining means. .