JPH02126414A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To easily discriminate whether or not a recording signal is surely recorded by directly performing follow-up scanning on the track of azimuth recorded with the aid of a fixed head with a movable head and detecting a signal recorded on a tape. CONSTITUTION:At the time of performing a recording action in a standard mode, the fixed head 2HR performs recording while traveling on a video track An in a direction shown by an arrow. The fixed head 2HL opposed to the head 2HR by 180 deg. is arranged at a position marked with a circle for starting writing in a video track Bn+1. At such a time, one movable head MVR having a mounting angle theta deg. traces the mark of circle of a video track An-1. The other movable head MVL is at the position of the mark of circle before shifting to a video track Bn. Therefore, at the time of performing recording on the track An with the head 2HR, or performing recording on the track Bn+1 with the head 2HL after reproducing the track An-1 with the head MVR, the track Bn is reproduced with the head MVL.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing device such as a video tape recorder (hereinafter referred to as VTR).

[Prior Art] Conventionally, automatic scan tracking (
Dynamic Track Follow Ink (hereinafter referred to as AST) and Dynamic Track Follow Ink (hereinafter referred to as DTP), which automatically perform tracking while moving the head in the width direction of the tape track during playback. A system configured as follows has already been developed.

FIG. 9 is a perspective view showing the drum structure of a rotary head device in a conventional magnetic recording/reproducing device.
1) and (2) are fixed heads for recording and playback.

(3) and (4) are special playback movable heads that operate during AST and DTP, and (5) and (6) are bimorph type piezoelectric elements that are attached to the above special playback movable heads (3) and (4). There is. (7) is a rotating drum which is rotated at 1800 rpm to which the above-mentioned recording/reproducing fixed heads (1), (2) and bimorph type piezoelectric elements (5), (6) are attached.

Figure fjSlo is an enlarged view of the actuator structure of the special playback movable heads (3) and (4) in a DTF system VTR. In the figure, (8) is a fixed drum, and (9) is a magnetic tape. be.

Furthermore, FIG. 11 shows the operating principle of the bimorph type piezoelectric elements (5) and (8) that have been used conventionally. Elements (5a), (5b), (8a), (8b)
It consists of a bimorph plate sandwiched between three electrodes (5c) and (6c), and the above-mentioned special reproduction movable heads (3) and (4) are attached to the free end of this bimorph plate. is installed. These special reproduction movable heads (3) and (4) have electrodes (5c)
, (Etc), piezoelectric elements (5a), (5b), (8a), (8b) due to the addition of AC voltage to
As shown in FIG. 10, the drum can be moved up and down in the axial direction (a-b) by the expansion and contraction of the drum.

Next, with reference to FIG. 12, the principle of the operation of the above-mentioned configuration in the case where, for example, high-speed playback operation is performed (noiseless speed search) will be explained.

11 Key Middle - Suso C5 - In Figure 12, A I, B 1. A2. B2
．． A 3゜B3 ・number indicates the video track recorded on the magnetic tape (8), C indicates the control track,
D indicates an audio track. Here A1.
A2. A 3...φ and B 1. B2. B 3-・
・This is a video track recorded with a head at a different azimuth angle.

Now, as an example of speed search, assume that playback is performed at 5x speed. When the piezoelectric element (5) for the special playback movable head (3) is not driven, the scanning locus of the special playback movable head (3) will be as shown by the broken line Ll in FIG. 3) Azimuth angle is A
If the azimuth angle of the tracks is the same, the reproduced signals will be from tracks AI, A2 . This is only the part where track A3 is scanned, and noise bars occur on the playback screen. Even if the videotape runs at 5x speed during playback, track A1
In order to completely regenerate the
3) is in contact with the magnetic tape (8) during one field period, the head (3) is moved 4 in the track axis direction (left side in the figure).
All you have to do is move the track pitch.In the 0th order field, another movable head dedicated to special playback (
4) by four track pitches.

In this way, AI, B3. A6: A noiseless reproduction signal is obtained by scanning the track completely. That is, by the above-described operation, noiseless reproduction at any speed can be realized by moving the special reproduction dedicated movable heads (3), (4) in the track width direction according to the tape speed during reproduction.

[Issue to be Solved by the Invention 11i1 The conventional magnetic recording/reproducing device equipped with a movable head is configured as described above, so that it is possible to
As shown in Figure 0, even if the tips of the heads (3) and (4) contact the tape (9) obliquely, a highly satisfactory reproduction performance can be obtained. However, in normal playback operations, the contact posture between the heads (:I), (4) and the tape (9) directly affects the C/N.
It is not preferable for the tip of the tape (9) to touch the tape (9) diagonally and move.

Furthermore, even if it is possible to determine whether or not a recording signal is being applied to the recording head during a recording operation, it is not possible to determine whether or not the recording signal was actually recorded on the tape without error. There wasn't.

In other words, there are cases where the head is so clogged that it doesn't actually record to tape, but I couldn't confirm that. In order to perform such recording discrimination, it is troublesome that a reproduction operation must be performed after the recording operation is interrupted or completed.

This invention has been made to solve the above-mentioned problems, and provides a magnetic recording and reproducing device that can determine whether or not a recorded signal has been reliably recorded on a tape during a recording operation. The purpose is to

[Means for Solving the Problems] A magnetic recording/reproducing device according to the present invention includes two recording/reproducing fixed heads attached to a rotating drum and having mutually different azimuth angles. The present invention is characterized in that a reproducing movable head is provided, and the movable reproducing head is drive-controlled so as to scan the same azimuth track already recorded by the fixed head during recording operation.

[Function] According to the present invention, during normal recording operation by the fixed head for recording and reproducing, the movable head immediately tracks and scans the azimuth track recorded by the fixed head to detect the signal recorded on the tape. do. by this,
By reproducing the recorded signal on the tape during the recording operation, it is possible to check whether recording is actually being performed without errors.

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

FIG. 1 is a longitudinal sectional view showing the drum structure of a rotating magnetic head device in a magnetic recording/reproducing apparatus according to an embodiment of the present invention. In the same figure, (7) is a rotating drum, (8) is a fixed drum, ( 10) is an electrode brush for applying current to the coil in the movable special reproduction head unit; (
tl) is a rotating slip ring, (12) is a drum motor, and (13) is a rotary transformer.

(100) is a movable special reproduction head unit, and at least the upper part of this head unit (100) and the rotary transformer (13) are fixed to the rotating drum (7), and the rotation of the drum motor (12) 1
It rotates at a constant speed of 800 rpm.

Figure 2 (a) shows the above movable special playback head unit) (
+00), and FIG. 2(b) is a longitudinal sectional view thereof, in which (tol) is shown.

(102) is a circular spring, and one of the circular springs (101
) A movable head (3), (4) for special reproduction is fixed to one end of the head. These circular springs (101), (102)
An air-core bobbin (103) is fixed to the center of the bobbin.

Also, the outer circumference of this air-core bobbin (103) has a diameter of 0.1 cm.
A winding coil (100 wires is wound) made of copper wire as thin as -.

(105) is a permanent magnet made of rare earth cobalt, etc.
10B) is a pole piece made of soft iron (107).

(108) is a yoke made of soft iron, which constitutes a drive mechanism for the movable heads (3) and (4). (109) is the cap, (110) is the winding coil (pudding to pull out 100) 7 & plate.

FIGS. 3(a) and 3(b) show the circular spring (101), (
102) is an enlarged cross-sectional plan view showing the configuration of FIG. 102) in detail. These two circular springs (lot), (102) are 0.08
Copper alloy plate (IOIA) with a thickness of am (102^)
As shown in Fig. 3(a) and (b), the slit (10
1b), (By forming a large number of 102a3, it has stable elasticity.A small molded part (IO
IB) and (102B) are fitted, and an air-core pobbin (103) with a coil is fixed therein.

On the other hand, at one end on the circumference of the circular spring (101), as shown in FIG.
As in a), movable heads (3) and (4) for special reproduction only.
is stuck.

As described above, the winding coil (104) is wound around the air-core bobbin (10'l) at two locations in FIGS. 3(a) and (b).
) A unit in which two circular springs (+01) and (102) are fixed is fixed to the inner surface of the yoke (107) by gluing or fitting. Circular wings (lot), (10
2) is fixed to the yoke (+07), and the air core bobbin (
103) Movable head for special playback due to overall movement (:
l) and (4) move vertically in parallel. This is the 4th
This will be explained in more detail based on the figures.

Section 41-a explains the operating principle of the head unit (+00) shown in FIGS. 2(a) and (b). As shown in FIG.
The outer peripheries of the circular springs (101) and (102) are fixed to the yoke (107). However, circular springs (10
1) has a long piece (101
a) has been taken out, and special playback dedicated movable heads (:l), (4) are attached to its tip. Also,
Inside the air core bobbin (10:l) is the permanent magnet (1
05) is arranged, and this permanent magnet (105) is connected to the yoke (
108).

Now, as shown in Figure 4, the permanent magnet (tOS) N,
S poles are provided above and below, and when current flows through the winding coil (104), a force acts in the direction of the arrow according to the left-hand rule of framing, and the air-core pobbin (103) moves downward. At this time, the outer circumferences of the circular springs (101) and (102) are fixed to the yoke (107).

Because it has a soft and uniform elasticity, it can be used as an air-core pobbin (
103) The whole moves downward in proportion to the magnitude of the current.

With this movement of the bobbin (103), the movable heads (3) and (4) for special reproduction, which are attached to the long piece (101a) of the circular spring (101), move downward in parallel. Furthermore, when the current flowing through the winding coil (104) is reversed, the air-core pobbin (103) moves upward in parallel, as shown by arrow B, contrary to the above.

As you can see from the above explanation, the movable head for special playback (
3) and (4) are the tape and special playback movable head (3) to move parallel up and down along the axial direction of the drum.
, (4) are always in full contact with each other so that the FM signal on the tape magnetic surface can be picked up to the maximum extent possible, and the tape is not damaged by the edges of the outer circumferential surface of the head.

FIG. 5 is a diagram showing the arrangement of heads in a rotating drum device. In the figure, (MVR) and (MVL) are both movable heads, and these movable heads (MVP).

(MVL) operates as shown in Fig. 4, and corresponds to the movable heads (3) and (4) in Fig. 1.
attached to the rotating drum (7) with a rotational phase of
and have mutually different azimuth angles. (2HL, 8
HR) and (2HR, 8HL) are fixed heads for recording and reproduction, each of which is a composite head having two azimuth angles and different head widths. These composite fixed heads (
2) When in standard mode, IL, θHR) and (2HR, GHL) record with a pair of opposing fixed heads (2HL) and (2HR), respectively, and the tape speed is reduced to 173 when in standard mode. When in 3x mode, the other set of fixed heads (13HL) and (13HR)
Let's record each one.

FIG. 6 is a diagram showing the head width and mounting steps of each head shown in FIG. 5 above.

As clearly shown in the figure, a composite fixed head (211
L, 611R) and (211R, 611L) are all deposited in alignment with the center as shown by the dashed line, so there is no level difference. On the other hand, U (Koku Head (MVR)
, (MVL)! , t and the composite fixed head (2HL,
61R) and (21fR, 6HL) with a stepped pattern attached to the center. Here, p is the track width (track width of VH3 standard moat is 58u, -), and θ° is the head mounting angle, which is 60°.

is set to .

Specifically, the stepped sentence in the case of the VHS system is sentence = 58 × -
Uichi + 2858 1sO = 135.3Bm, and the movable head (MVL)
and (IIVR) are translated in the x-y direction (77) in FIG.

Next, the relationship between the respective heads during the recording operation will be explained in detail with reference to FIG. 7, which shows the head positions on the tape pattern.

Assume that a standard mode recording operation is now performed. That is, the fixed head (2HR) is connected to the video track (An
) is running in the direction of the arrow and the moment of recording is set to 0, then the fixed head (2
HL) is placed at the writing start position 0 on the video track (Bn◆1). At this time, one movable head (MVR) having an attachment angle θ0 is 13
Since there is a step of 5.3JL-, the 0 point of the previous video track (An-1) is traced. Further, the other movable head (MVL) is located at position 0 before moving to the video track (Bn).

Therefore, with a fixed head (2HR) and a video track (
When recording with the movable head (An), the movable head (V
R) can play the video track (An-1), and the fixed head (2HL) can play the track (Bn+1).
While recording the track (Bn), the movable head (MVL) can play back the track (Bn).

In addition, a movable head (with a step height of 135.31 Lm)
In order to accurately trace MVR) and (MVL) over the entire video track length as shown in FIG. 7, the movable head is slightly moved to select the optimum value.

FIG. 8 is a block diagram showing the configuration of the drive system of the above-mentioned rotating drum device, and shows an envelope detection signal obtained by detecting an envelope signal in playback mode, an FG multiplied signal obtained by a capstan frequency oscillator (FC), and a control signal. The movable head is generated by the pattern generation circuit (120) and the microcomputer (121) based on the GL multiplied signal generated in response to the travel control signal (CTL signal) picked up from the tape (θ) by the head (CH). Calculate the amount of movement in (3) and (4). The calculated value is sent to the adder circuit (122), (123), the filter circuit (124), (125), and the gain adjustment circuit (
128), (127), current amplifier (12B), (1
29) The movable head (
3), and (4) control the drive movement.

That is, the position of the video track with respect to the rotation plane of the movable heads (3) and (4) is controlled by the control signal (CTLi).
(No.) and the FG multiplied signal from the capstan frequency oscillator (FC) that effectively divides it is detected and corrected.

In other words, when the magnetic tape playback speed is faster than the reference speed, the control current is applied to displace the movable heads (3) and (4) downward in the drum axis direction from the reference head position (corresponding to the step pattern) at the reference speed. When the playback speed is slower than the standard speed, a control current is generated that displaces the movable heads (3) and (4) upward in the drum axis direction from the standard head position (corresponding to the step position). .

With such a configuration, the position of the head with respect to the video track at any tape running speed can be calculated, and by correcting this, the position of the movable head (3), ( 4) can be accurately traced over one field period.

In the above embodiment, the head is attached at an angle θ
0 was selected as 60', but it is not limited to this.
When installing the head, set the step pattern in pxz according to the angle θ0.
+2p and then attaching it to a rotating 180' drum, driving it as shown in FIG. 8 in accordance with reproduction envelope detection during actual operation, and performing fine-tuned tracking, the same effect as in the above embodiment can be achieved.

[Effects of the Invention] As described above, according to the present invention, the recorded signal can be immediately reproduced during the recording operation, so it can be easily confirmed whether the recorded signal is recorded on the tape without error. can be determined. In addition, this type of discrimination can help identify one of the causes of serious situations where a recording signal is not actually recorded on the tape even though it is being applied to the recording head.
This has the effect of making it possible to check whether the head is clogged.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the drum structure of a rotating magnetic head device in a magnetic recording/reproducing apparatus according to an embodiment of the present invention, and FIGS. 2(a) and 2(b) are perspective sectional views showing the structure of the head unit. Longitudinal cross-sectional view, Figure 3 (a), (b)
) is an enlarged cross-sectional view showing the configuration of the circular spring, FIG. 4 is a schematic vertical cross-sectional view of the main parts explaining the operating principle of the head unit,
Fig. 5 is a schematic plan view showing the arrangement of heads in a rotating drum device, Fig. 6 is an explanatory diagram of the head width of each head and mounting steps, and Fig. 7 is an illustration of the positional relation of each head on the tape. 8 is a block diagram showing the configuration of a drive system for a rotating drum device, FIG. 9 is a perspective view showing a drum structure of a rotating drum device in a conventional magnetic recording/reproducing device, and FIG. FIG. 11 is an enlarged sectional view illustrating the operation of the head, FIG. 11 is a diagram illustrating the operating principle of a bimorph piezoelectric element, and FIG. 12 is a diagram illustrating the operation of a conventional device. (3), (4)...Movable head for reproduction, (7)...
・Rotating drum, (8)...Fixed constant! 'Ram, (100
)...Head unit, (2HL, El)IR), (
2HR, 8HL)...Composite fixed head. Note that the same symbols in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A rotating drum, two recording/reproducing fixed heads attached to the rotating drum having different azimuth angles, and a reproducing movable head attached to the rotating drum and movable in parallel in the axial direction of the rotating drum. a drive mechanism that moves the movable head in parallel in the axial direction of the rotating drum; and a drive that controls the drive mechanism so that the movable head scans over the same azimuth track that has already been recorded when the fixed head performs a recording operation. What is claimed is: 1. A magnetic recording and reproducing device comprising a control means.