JPH02162979A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate the need for increasing number of magnetic heads even with a small diameter cylinder and to obtain a device interchangeable with a conventional device by recording a video signal while compressing it and expanding it at reproduction. CONSTITUTION:An inputted video signal is given to an A/D conversion circuit 24, separated for each field at a switching circuit 25, the separated signals are inputted to 1st and 2nd time compression circuits 28, 29 respectively, in which time compression and delay are implemented, then given to 1st and 2nd D/A conversion circuits 30, 31, 1st and 2nd FM modulation circuits 32,33 and recording amplifiers 34, 35 and given to a CH 1 magnetic head 3 and a CH 2 magnetic head 4 as recording signals. The number of revolutions of a cylinder 21 is given by a drive circuit so that the cylinder 21 is turned once at a 1 field scanning period fv and an outer diameter D3 of the cylinder 21 is selected to be D3=(180 deg./A)XD1 being equal to a track length.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing device such as a VTR.

[Prior Art] FIG. 9 is a schematic plan view showing the arrangement of magnetic heads in a conventional two-head recording force type magnetic recording and reproducing apparatus for recording and reproducing video signals such as NTSC and PAL. 1) is a cylinder, (2) is a magnetic tape wound around this cylinder (1) at an angle A=180@, (3) is a CHI magnetic head having an azimuth angle βl,
(4) is a CH2 magnetic head with an azimuth angle β2,
These CHI magnetic heads (3) and CH2 magnetic heads (4)
) are spaced apart from each other by a rotational phase of 180@ and the cylinders (
1).

Figure 10 shows how a magnetic tape (2
) shows the magnetic pattern recorded in (
5) is the audio recording track recorded on the upper side of the magnetic tape (2), (6) is the control track recorded on the lower side, (7) is the CH1 track recorded by the CH1i head (3), (8) is the CH2) rack recorded by the CH2 magnetic head (4). The angle that these CHI track (7) and CH2 track (8) make with the longitudinal direction of the magnetic tape (2), that is, the scanning angle θ, is
The predetermined value is determined by the interrelationship among the running speed of the magnetic tape (2), the diameter of the cylinder (1), and the rotational speed of the cylinder (1).

Figure 11 shows the switching waveforms of each magnetic head in the recording mode, and the CHI magnetic head (3) and CH2 magnetic head (4) alternately switch for a predetermined period of time as shown in (a) and (b) of the same figure. For example, in the case of NTSC, it is ON for 16.68 rasec of l field scanning time.

Means for obtaining such a magnetic pattern on the magnetic tape (2) is not limited to the configuration shown in FIG. 9, but the following configurations have also been considered in the past.

FIG. 12 is a schematic plan view showing the arrangement of the magnetic head in another conventional magnetic recording device disclosed in, for example, Japanese Patent Publication No. 61-14566, in which (9) is a cylinder; is wrapped around this cylinder (9) at angle A=
Magnetic tape wrapped at 270°, (10) to (1
3) is a magnetic head attached to the outer periphery of the cylinder (1), C) If A magnetic head (10) and CHI B magnetic head (11) have the same azimuth angle β1, and CH2
The A magnetic head (12) and the CH2B magnetic head (13) have the same azimuth angle β2. The four magnetic heads (10) to (13) are attached to each other at an angle of 9.
It is installed so that it is at 0°.

The outer dimensions of the cylinder (9) are as shown in Fig. 9 (
The outer diameter dimension of 1) is 180/270=2/3. For example, if the outer diameter of cylinder (1) in Fig. 9 is DI=6
2t+s, the outer diameter of the cylinder (9) in FIG. 12 is D2 = 41. :l:l■■.

FIG. 13 shows switching waveforms during recording by the magnetic head shown in FIG. 12. Cylinder (9) is the first
Rotate counterclockwise as shown by the arrow in Figure 2, and C
The period during which the HI A magnetic head (10) is in contact with the magnetic tape (2), that is, the winding is 270', and the scanning time for one field is 16.68 m5ec.

In, the other three magnetic heads (11), (12),
No recording current is applied to (13). Next, CH2
A recording current is applied to the A magnetic head (12), and recording for one field is performed. In this way, the magnetic head to which the recording current is sequentially applied is as shown in (a) to (d) in FIG.
As shown, CHIA(10)-CH2A(12)-
The cylinder (9) rotates three times and returns to the initial state.

The magnetic pattern of the magnetic tape (2) recorded in the above manner is the same as that shown in FIG. 1O. That is, the track recorded by the CHI A magnetic head (10) corresponds to the track (7) in FIG.
2A magnetic head (12) tracks (8), CHI
B (11) corresponds to track (7a), and CH2B (13) corresponds to track (8a), respectively. Also.

Since the magnetic heads CHIA (10) and CHIB (11) or CH2A (12) and CH2B (13) have the same azimuth angle, the tracks have no difference on the magnetic pattern. Furthermore, magnetic tape (2)
Since the running speed of the magnetic tape and the relative speed of the magnetic head with respect to the magnetic tape are the same as in FIGS. 9 to 11, the track scanning angle .theta. also has the same value as in FIG. 1.theta.

FIG. 14 shows a conceptual diagram of a track pattern drawn by the magnetic recording/reproducing apparatus configured as shown in FIG. 12. In the figure, when the magnetic tape (2) is stationary, the magnetic head starts from point P and reaches point Q by one field scanning as the cylinder (9) rotates.

Furthermore, while the magnetic tape (2) is running, the scan end position is shifted by the amount that the magnetic tape moves during l-field scanning. That is, the magnetic head starts from point P and reaches point R. Here, the scanned track length is
PQ=uTo when stationary, PRIIT when running, scan angle is 00 when stationary, θ when running, QR=49
．． If V, then θO can be found as shown in the following equation.

Figure 15 shows the cylinder (9) in the apparatus shown in Figure 12.
) is a perspective view showing the winding state of the magnetic tape (2), in which (14) is the lower cylinder; (14) is the lower cylinder;
5) is a lead formed on this lower cylinder (14) and contacts the edge of the magnetic tape (2) to guide its running; (16) is a scanning locus of the magnetic head attached to the cylinder (9); , (17), (18) are magnetic tape (
2) Guide roller that regulates widthwise fluctuation, (19)
, (20) is this guide roller (17).

This is a slant ball that is installed in a twisted state with respect to (18) and changes the running angle of the magnetic tape (2). In addition, in this figure, the angle that the lead (15) makes with respect to the scanning trajectory (16) of the m% head is called the lead angle. It coincides with the scanning angle θ0.

For example, if the tape running speed is 33.35 +u+ /s
ec.

Then, l V = 33.35 mm/sec,
0.5558 mm1T= 96.836 am
, θ=5.9694'', then θo=5.
9354'' can be obtained.

That is, by forming the lead (15) so that the lead angle θo = 5.9:154'', the scanning angle θ = 5.9894'' can be obtained at a tape running speed of 13.35 mm/sec. Can be done.

Note that when comparing the configuration shown in FIG. 9 and the configuration shown in FIG. 12, if IV, T, and θ are set to the same values, the lead angles will also have the same value of θ0.

[Problems to be solved by the invention] As described above, the patent publication No. 61-145 shown in Figs.
In the conventional magnetic recording/reproducing device described in Publication No. 66, the same magnetic pattern as shown in FIG. 1O can be achieved using a small diameter cylinder as shown in FIG. It is easy to reduce the weight, but compared to a conventional magnetic recording/reproducing device that has the arrangement of magnetic heads as shown in Figure 9, the number of magnetic heads is doubled, and this increase in the number of magnetic heads causes There are problems in that there is a large increase in parts cost and adjustment cost, and dimensional restrictions are caused by attaching a large number of magnetic heads to a small diameter cylinder.

This invention was made to solve the above-mentioned problems, and its purpose is to provide a magnetic recording and reproducing device that can be made compact and lightweight using a small-diameter cylinder and that does not require an increase in the number of magnetic heads. shall be.

[Means for Solving the Problems] A magnetic recording/reproducing device according to the present invention has two magnetic heads attached to a cylinder at a predetermined relative angle and with a step difference, and the magnetic tape is run at a predetermined angle at a predetermined winding angle. At the same time, the cylinder is rotated at a rotation speed synchronized with the 1-field frequency of the video signal, and during recording, the video signal compressed to A/360' is scanned by a magnetic head, and during playback, the signal scanned by the magnetic head is scanned. It is characterized in that the reproduced video signal is obtained by expanding the video signal to 360''/A.

[Function] According to the present invention, the magnetic head scans the magnetic tape at a speed of 360°/A, and a video signal compressed to A/360' is applied to the magnetic head, so that it is the same as the conventional method. A magnetic pattern is obtained. Therefore, it is possible to obtain a device that is compatible with conventional magnetic recording and reproducing devices while using a small-diameter cylinder and having a configuration in which the number of magnetic heads does not increase.

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

FIG. 1 is a plan view showing the configuration of the main parts of a magnetic recording and reproducing apparatus according to an embodiment of the present invention.
) is a cylinder that rotates counterclockwise, and the magnetic tape (2
) is wrapped around this cylinder (21) at a wrapping angle A. In this winding, the angle A is the angle that governs electromagnetic conversion, and in the mechanical winding, the angle is the value of A plus a margin of about 5°. The magnetic tape (2) runs in the direction (a) in the figure,
The slant ball (19) is located on the inlet side of the cylinder (21).
), and is wrapped around the slant ball (20) on the exit side. (3) is the CHI magnetic head attached to the outer periphery of the cylinder (21), and (4) is this CHI magnetic head (
In the CH2 magnetic head attached to the cylinder (21) at a relative angle α from 3), electromagnetic conversion starts from the inlet side switch position (22a), and the electromagnetic conversion starts from the outlet side switch position (22b). The electromagnetic conversion ends at .

FIG. 2 is a perspective view showing how the magnetic tape (2) is wound around the cylinder (21) in FIG. formed reed, (54)
is a magnetic head (3) attached to a cylinder (21)
.

The scanning trajectory of (4), (17) and (18) are the magnetic tape (
2) is a guide roller that regulates the widthwise fluctuation.

FIG. 3 shows a side view of FIG. 1, in which the CHI magnetic head (3) has an azimuth angle of β1, the CH2 magnetic head (4) has an azimuth angle of β2, and the cylinder (21) has an azimuth angle of β2. ) are juxtaposed.

'Figure 4 shows the relative heights of the two magnetic heads (3) and (4). CHI magnetic head (3)
In contrast, the CH2 magnetic head (4) is attached with a delay of a relative angle α, so in order to correct this, a head attachment step corresponding to ΔH in the following equation is provided.

△H=−−−×(track pitch)・・・036
0m FIG. 5 is a block diagram showing the configuration of the recording system of the magnetic recording/reproducing apparatus configured as shown in FIGS. 1 to 3. In the figure, (23) is the input terminal of the video signal to be recorded, (24) is the A/D conversion circuit, (25) is the switching circuit, and C) 11 side output (26) and CH2 side output (
27) and are output separately. (28) is the first time compression circuit connected to the CHI side output 6), (29)
is the second time compression circuit (2) connected to the CH2 side output (27). (30) and (31) are the first and second D/A conversion circuits, (32) and (33) are the first
and a second FM modulation circuit, (34) and (35) are recording amplifiers, (3) is a CHI magnetic head connected to the recording amplifier (34) side, and (4) is connected to the recording amplifier (35) side. This is a CH2 magnetic head. (36) is a synchronization separation circuit branched from and connected to the input path of the video signal;
A memory control circuit (37) outputs a switching timing instruction to the switching circuit (25).

FIG. 6 is an output timing chart showing the time axis deviation between the video signal and the recording signal recorded on the magnetic head.

FIG. 7 is a block diagram showing the structure of the reproducing system of the magnetic recording and reproducing apparatus constructed as shown in FIGS. 1 to 3. In the figure, (38) is a reproduction amplifier that amplifies the output signal obtained from the CHI magnetic head (3), and (39) is a C
A reproducing amplifier that amplifies the output signal obtained from the H2 magnetic head (4), (40) and (41) are the first and second F
M demodulation circuit, (42) and (43) are the first and second
(44) is the CHI magnetic head, (45) is the first time expansion circuit for the digital signal on the side, and (45) is the CH2 magnetic head.
A second time expansion circuit for the digital signal on the magnetic head side, (
46) is a switching circuit, and the output on the CHI side (47)
and CH2 side output (48) are switched and coupled to the D/A conversion circuit (49). (5o) is an output terminal for a video signal that is D/A converted and output, and (51) is a memory control circuit that instructs the switching timing to the switching circuit (46).

FIG. 8 is an output timing chart showing the relationship between the reproduction signal output from the magnetic head and the video signal obtained via A/D conversion and D/A conversion.

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

The magnetic tape (2) runs from the direction a shown in FIG.
It is set at about 70' + 10", and magnetic tape (2
) in this wrapped section, the lead (53
), and fluctuations in the tape width direction are regulated. The angle formed by the travel locus (54) of the magnetic heads (3), (4) and the lead (53) is given by C0. After passing through the cylinder (21), the magnetic tape (2) passes through a slant ball (20) and a guide roller (18), and travels toward the camp stun shaft (not shown).

The cylinder (21) rotates counterclockwise as shown in FIG.
) reaches the switching position (22a) on the inlet side of
C) Electromagnetic conversion in the 11 magnetic head (3) is started.

After a while, the CH2 magnetic head (4) also comes into contact with the magnetic tape (2), but no electromagnetic conversion is performed in the CH2 magnetic head (4) yet.

As the cylinder (21) rotates, the CHI magnetic head (3) rotates and moves to the exit side switching position (22).
When b) is reached, the electromagnetic conversion in the CHI magnetic head (3) ends. The switching position fil (22
The relative angle between a) and the switching position (22b) on the outlet side, that is, the winding angle A where electromagnetic conversion takes place, is 2.
It is set at 70°.

Then, after the CHI magnetic head (3) passes the switching position (22b) on the exit side, the CH2 magnetic head (
There is an idle running period in which neither of the magnetic heads (3) and (4) undergoes electromagnetic conversion until the head (4) reaches the switching position on the entrance side. Before the CH2 magnetic head (4) reaches the inlet switching position (22a), the CH1m81 magnetic head returns to the inlet switching position (22a).
However, this time no electromagnetic conversion is performed in the CHI magnetic head (3).

The electromagnetic conversion in the CH2 magnetic head (4) is as follows:
This is done at the time of the second rotation, and the CH2 magnetic head (4
) continues until the outlet side switching position (22b) is reached. After the second idle running period, the process returns to electromagnetic conversion in the CHI magnetic head (3). In this way, every rotation of the cylinder (21), electromagnetic conversion by the CHI magnetic head (3) and electromagnetic conversion by the CH2a1 magnetic head (4) are performed alternately, and at the time of each conversion, the electromagnetic conversion of which magnetic head is This results in an idle running period in which no conversion occurs.

As described above, the intermittent recording signal is transferred to the magnetic head (3).
(4), the following signal processing is performed. That is, in FIG. 5, the video signal input from the terminal (23) passes through the A/D conversion circuit (24), and then is separated into l fields by the switching circuit (25), each of which is divided into the first and second fields. 2 time compression circuit (
28) Input to 8 and (29) for time compression and delay. Then, each of the time-compressed and delayed signals is sent to NSL and a second D/A conversion circuit (30).
, (31), first and second FM modulation circuits (32)
, (33), recording amplifier (34).

(35) to CHl magnetic head (3) and CH2
The signal is given to the magnetic head (4) as a recording signal.

The relationship between the recording signal compressed and delayed by one hour as described above and the original video signal is shown in FIG. 6. In this FIG. 6, if the field frequency of the video signal shown by C8) is fv, the signal of the first field is fv
+Δt1 delay, compressed to (A/360 x fv) and applied to the CHI magnetic head (3).
Compared to the CHI magnetic head (3), the 2 magnetic head (4) is attached with a delay in the timing of contact with the Bi magnetic tape 2) by pitch α, so the second field signal is even more sensitive than the first field signal. It is necessary to delay (α/360") x fv. That is, the second field signal is delayed by fv + △jl + (a / 360 times ) is applied to

The rotation speed of the cylinder (21) is rotated by a drive circuit (not shown) so that the cylinder (21) rotates once in one field scanning period fv, and the outer diameter D3 of the cylinder (21) is as shown in FIG. It is assumed that D:1=(180°/A)×Dl is set to have the same value as the track length shown in FIG.

Hereinafter, as an example, numerical calculations that are compatible with those shown in FIGS. 9 and 12 will be performed using NTSC signals.

The winding angle A = 270°, and the outer diameter D3 of the cylinder (21) is: D3 = (180°/270@) x 62mm = 41
．． Assuming that the 33mm tape running speed is 33.35++ m/sec, which is the same as in Figures 9 and 12, the time required to record the l-field signal on the magnetic tape (2) is 1750 seconds x 180'''/270' = 11.11m
5ec, so I transferred the 1 field signal to the magnetic tape (2
) The amount 1v that the magnetic tape moves during recording is lv = 33. :15ss/5ecx +1.1
1 x 10 5ec = Oj706mm The track length fLT when the tape runs and the scanning angle θ are the same values as in FIGS. 9 and 12 for compatibility, that is, IT = 96.8:16 mm, θ = 5.
9694", the scanning angle when the tape is stationary, that is, the lead angle θot, was 5.9:154@ in the conventional embodiment shown in FIGS. 9 and 12, so this 001 = 5, which is a larger value than the lead angle θO in the conventional embodiment
．． By forming the lead (53) with a lead angle of 9467', the same scanning angle θ as in the conventional embodiment can be obtained during running, and a magnetic recording/reproducing device that maintains compatibility can be obtained.

In this way, the same recording pattern as in the conventional example can be recorded.

Next, the playback operation will be explained.

In Fig. 7, the signals reproduced from C) (1 magnetic head (3) and CH2 magnetic head (4) are time-compressed as shown in Fig. 8, and are divided and reproduced by both heads for each l field. These reproduced signals pass through first and second FM demodulation circuits (40) and (41), respectively, and are input to first and second A/D conversion circuits (42) and (43) where they are converted into digital signals. The signal is then converted into a signal.Then, the signal is time-delayed through first and second time expansion circuits (44) and (45), and converted into one system of digital signals at a switching circuit (4B).

These l systems of digital signals are outputted from a terminal (50) as a video signal through a D/A conversion circuit (48).

Here, as shown in FIG. 8, the CHI magnetic head (3)
The first field reproduction signal obtained from 360'/
The signal is expanded by A and delayed by A/360°×fma+Δt2 to become the first field video signal. Also, since the CH2 magnetic head (4) is attached with a relative angle α behind the CHI magnetic head (3), it is necessary to return the delay by α/360 x fv. Therefore, 360”/A
It is expanded, (A/360 x fv+△t2-(Q
/360'') X fv and becomes the second field video signal.

In the manner described above, by passing through the reproduction signal processing circuit shown in FIG. 7, it is possible to obtain a video signal in the same format as that input at the time of recording.

In addition, in the above embodiment, the winding is performed at the angle A and the cylinder diameter D.
3 is the same value as in the conventional embodiment shown in FIG. 9, however, the angle A of this winding can be set to any value from about 180 DEG to 300".

[Effects of the Invention] As described above, according to the present invention, by compressing and recording a video signal and expanding it during playback, there is no need to increase the number of magnetic heads even if a small diameter cylinder is used. ,
A device can be obtained that is compatible with conventional devices.

Therefore, it is possible to suppress an increase in component costs and adjustment costs due to an increase in the number of magnetic heads, and to obtain a device that does not suffer from dimensional restrictions caused by mounting a large number of magnetic heads on a small diameter cylinder. can.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the configuration of essential parts of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view of FIG. 1, FIG. 3 is a side view of FIG. 1, and FIG. is an enlarged view of the main part of FIG. 3, FIG. 5 is a block diagram showing the configuration of a recording system of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, and FIG. 6 is an illustration of the output obtained by the circuit of FIG. 7 is a block diagram showing the configuration of a reproducing system of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, FIG. 8 is a timing diagram of the output obtained by the circuit of FIG. 7, and FIG. 9 is a conventional diagram. 10 is a plan view showing the configuration of the main part of the magnetic recording/reproducing device of FIG.
FIG. 12 is a plan view showing the configuration of main parts of another conventional magnetic recording/reproducing device; FIG. 13 is a switching waveform diagram during recording by the device shown in FIG. 12; Fig. 14 is a schematic diagram of magnetic pattern calculation using the apparatus shown in Fig. 9 or Fig. 12;
FIG. 3 is a perspective view of the device of FIG. 2; (2)...magnetic tape, (3)...CHI magnetic head, (4)...CH2 magnetic head, (21)...cylinder, (2nd), (29)...first and a second time compression circuit, (44), (45)...first and second time expansion circuits. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A magnetic tape that is wound around the outer peripheral surface of a cylinder at a predetermined angle and runs, and a magnetic tape that rotates coaxially with the cylinder.
In a magnetic recording/reproducing device comprising a pair of magnetic heads and configured to perform diagonal scanning on the magnetic tape with the magnetic heads, the winding angle at which the magnetic heads contact the magnetic tape and perform magnetic conversion is A. When
1 field or 1 frame of video signal approximately A/36
A time compression circuit that compresses the signal to 0°, a time expansion circuit that expands the compressed signal to about 360°/A, and a drive circuit that rotates the magnetic head at a rotation speed synchronized with the field frequency of the video signal. During recording, a video signal compressed to approximately A/360° is recorded on the magnetic tape for each field frequency of the video signal, and during playback, the signal reproduced from the magnetic tape is expanded to approximately 360°/A. A magnetic recording/reproducing device characterized in that it is configured as follows.