JPH081692B2 - Magnetic recording / reproducing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnetic recording / reproducing apparatus such as a video tape recorder (hereinafter referred to as a VTR).

[Prior Art] Conventionally, for example, in a 1-inch helical VTR for broadcasting, it has been called automatic transmission / skiyan tracking (hereinafter referred to as AST) or dynamics tracking / following (hereinafter referred to as DTF). Some of them have already been developed such that the head is automatically moved while moving the head in the track width direction of the tape during reproduction.

FIG. 7 is a perspective view showing a head structure of a rotary head device in a conventional magnetic recording / reproducing apparatus. In FIG.
(1) and (2) are fixed heads for normal recording and reproduction,
(3) and (4) are movable heads dedicated to special reproduction that operate during AST and DTF, and (5) and (6) are bimorph type piezoelectric elements.
The movable heads (3) and (4) dedicated to special reproduction are attached. (7) is a rotary drum, which is attached with the recording / reproducing fixed heads (1) and (2) and the bimorph type piezoelectric elements (5) and (6) and is rotated at 1800 rpm.

FIG. 8 is a diagram showing an enlarged structure of the actuator portion of the heads (3) and (4) which can be used only for special reproduction in the DTF VTR. In FIG. 8, (8) is a fixed drum,
(9) is a magnetic tape.

FIG. 9 shows the operating principle of the above-mentioned bimorph type piezoelectric elements (5) and (6) which have been conventionally used. The bimorph type piezoelectric elements (5) and (6) are composed of two piezoelectric elements. The elements (5a), (5b), (6a) and (6b) are composed of a bimorph plate sandwiched between three electrodes (5c) and (6c) in the shape of a saint-Gerache. Movable heads (3) and (4) dedicated to special reproduction are attached. This special playback movable head (3),
(4) is a piezoelectric element (5a), (5b), (6a), (6b) which accompanies applying an alternating voltage to the electrodes (5c) and (6c).
As shown in FIG. 8, it is structured such that it can be moved up and down in the axial direction (ab) of the drum by the expansion and contraction action.

Next, the operation of the above configuration will be described with reference to FIG. 10 for the principle of a high-speed reproduction operation (noiseless speed search).

In FIG. 10, A1, B1, A2, B2, A3, B3 ... Show video tracks recorded on the magnetic tape (9), C is a control track, and D is an audio track. Here, A1, A2, A3 ... And B1, B2, B3 are video tracks recorded in a head having a different azimuth angle.

Now, as an example of speed search, assume the case of reproducing at 5 × speed. When the piezoelectric element (5) for the special playback-only movable head (3) is not driven, the scanning locus of the special playback-only movable head (3) becomes as shown by the broken line L in FIG. When the azimuth angle of (3) is the same as the azimuth angle of the A track, the reproduced signal is only a portion for scanning the tracks A1, A2, A3, and a noise bar is generated on the reproduction screen. Here, in order to completely reproduce the track A1 even if the tape runs at 5 times speed during reproduction, in order to completely reproduce the track A1, the head for special reproduction (3) contacts the magnetic tape (9) during one field period. 3)
Need only be moved by 4 track pitches in the track axis direction (left side in the figure). At the next field, another special playback movable head (4) will be moved by 4 track pitches.

In this way, A1, B3, A6 ... Tracks are completely scanned and a noiseless reproduction signal is obtained. That is, by the above-described operation, the movable heads (3) and (4) dedicated to special reproduction are moved in the track axis direction according to the tape speed during reproduction, so that not only normal reproduction but also noiseless reproduction at any speed can be realized.

FIG. 11 shows a block circuit diagram of a conventional automatic tracking device. In the figure, (10) is a rotary transformer, (11) is a head amplifier for normal reproduction, which amplifies a minute level reproduction FM signal picked up by the fixed heads (1) and (2) for recording and reproduction, and a timing generator. The video signal V is input to the reproduction signal processing circuit (13) through the switch (12) which is switched by the output signal of (36).
Demodulated to. Reference numeral (14) is a search head amplifier, which is movable heads (3), (4) when, for example, 5x speed reproduction is performed.
The reproduced FM signal of a minute level picked up by is amplified by. (15) is an envelope detection circuit for detecting the envelope of the reproduced FM signal, (16) is a drive voltage signal for the bimorph type piezoelectric elements (5) and (6) at the time of search (hereinafter,
A micro computer that outputs a search correction signal, (17) is an FG counter that counts the capstan FG signal (hereinafter, CP / FG signal) and is reset by a control signal (hereinafter, CTL signal), (18) is a comparator, (19) is a floating counter, (20) is a speed counter, (21a) and (21b) are output counters, (22
a) and (22b) drive adders, (23a) and (23b) drive low-pass filters (hereinafter referred to as LPFs), and (24a) and (24b) drive bimorph piezoelectric elements (5) and (6). The high voltage amplifier (25) is a vertical sync separation circuit (hereinafter referred to as a V sync separation circuit).

The conventional automatic tracking device shown in FIG.
Signal, CP / FG signal and head switch signal (hereinafter, HS
The signal waveform of the driving voltage e for driving the bimorph type piezoelectric elements (5) and (6) is determined by inputting a signal (referred to as W signal) as an input. That is, the CP / FG signal is counted by the FG counter (17) reset by the CTL signal and supplied to the comparator (18). The threshold value of the comparator (18) is determined by the speed counter (20). This threshold value is preset in the floating counter (19) by the output of the comparator (18).
The output signal of the floating counter (19) is supplied as the preset value of the output counters (21a) and (21b). These output counters (21a) and (21b) use the preset value input from the floating counter (19) as HSW.
A counter that presets when the signal rises or falls,
A search correction signal for correcting the output signals of the output counters (21a) and (21b) with the envelope detection signal input from the envelope detection circuit (15) as a reference by the micro computer (16) for 5 × speed reproduction. Are added by adders (22a) and (22b) respectively, and the ripple components of these output signals are removed by LPFs (23a) and (23b), which are applied to high-voltage amplifiers (24a) and (24b). The automatic tracking operation is performed by driving the piezoelectric elements (5) and (6).

[Problems to be Solved by the Invention] Since the conventional magnetic recording / reproducing apparatus having a movable head is configured as described above, it is possible to perform a noiseless speed search or a special reproducing operation such as still or slow motion as shown in FIG. As shown in, even if the tips of the movable heads (3) and (4) are in contact with the magnetic tape (9) at an angle, almost satisfactory reproducing performance can be obtained. However, since the contact attitude between the movable heads (3) and (4) and the magnetic tape (9) in the normal reproducing operation and recording operation directly affects the C / N, the tips of the movable heads (3) and (4) are affected. When the movable head moves and comes into contact with the surface of the magnetic tape (9) obliquely, that is, like a point a or b in FIG. (3) Since the tips of (4) and the surface of the magnetic tape (9) do not contact each other at a right angle, the C / N becomes significantly worse,
Satisfactory playback performance cannot be obtained.

Also, during normal playback operation, the movable head (3),
By operating (4) so that the level of the playback FM signal is maximized, the playback performance can be improved, but
Movable heads (3), (4) during normal recording operation
There is no standard that determines the behavior of. For example, even if a correct recording operation is performed in conformity with the tape format of the VHS system VTR, it is not possible to detect a reference signal for behavior control from the magnetic tape.

For the above reasons, it is difficult to correctly perform the normal recording / reproducing operation with the movable head. Therefore, in the conventional magnetic recording / reproducing apparatus, the movable head is exclusively used as the special reproducing head. As a result, the number of heads increases and the number of tape-tapping phenomena increases, which tends to cause jitter, and the cost increases.

The present invention has been made to solve the above-mentioned problems, and is not only noiseless at the time of special playback such as speed search by only a pair of movable heads, but also improvement of C / N at the time of normal playback and normal playback. It is an object of the present invention to provide a magnetic recording / reproducing apparatus that enables accurate behavior control conforming to a standard format at the time of recording and is effective in terms of both performance and cost.

[Means for Solving the Problems] A magnetic recording / reproducing apparatus according to the present invention includes a rotating drum, a recording / reproducing movable head attached to the rotating drum so as to be movable in parallel in the axial direction, and the movable head. An electromagnetic drive mechanism that moves the device parallel to the axial direction of the rotating drum by a distance corresponding to the supply current, an envelope detection unit that generates an envelope detection signal from a signal reproduced by the movable head, and a recording medium corresponding to the traveling speed of the recording medium. A calculating means for correcting the generated reference signal by the envelope detection signal so that this envelope detection signal is maximized,
The recording means is provided with a storage means for storing a signal obtained by correcting the reference signal generated corresponding to the traveling speed of the recorded standard recording medium by the calculating means by the envelope detecting signal so that the envelope detecting signal is maximized. The movable head is moved to a predetermined position by an electromagnetic drive mechanism which is controlled based on the signal read from the means to record,
At the time of reproduction, it is characterized in that the movable head is moved and reproduced by an electromagnetic drive mechanism controlled based on the output signal of the calculation means.

[Operation] According to the present invention, the pair of movable heads are brought into surface contact with the magnetic tape so that the level of the reproduced FM signal is maximized in both the special reproduction such as the speed search and the normal reproduction. By performing automatic tracking while it is being performed, noiseless special playback and good normal playback with good C / N can be performed. Further, during the recording operation, the tape recording format at the time of good reproduction operation as described above is read out, and the behavior of the movable head is controlled with reference to this, so that correct recording can be performed by the movable head. As described above, since all operations of special reproduction and normal recording / reproduction can be performed with only one pair of movable heads, the number of heads on the rotating drum can be reduced, and the occurrence of jitter due to the tapping phenomenon of the tape can be suppressed. At the same time, the cost can be reduced.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view showing a drum structure of a rotary magnetic head device in a magnetic recording / reproducing apparatus according to an embodiment of the present invention. In FIG. 1, (7) is a rotary drum, and (8) is a rotary drum.
Is a fixed drum, (10) is an electrode brush for applying a current to a coil in a movable head unit described later, (11) is a rotating slip ring, (12) is a drum motor, (1)
3) is a rotary transformer.

(100) is a movable head unit, and at least the head unit (100) and the rotary transformer (1
The upper part of 3) is fixed to the rotating drum (7),
The drum motor (12) rotates at a constant speed of 1800 rpm.

FIG. 2 (a) is a perspective sectional view showing the structure of the movable head unit (100), and FIG. 2 (b) is a longitudinal sectional view thereof, wherein (101) and (102) are circular springs. , A movable head (3) at one end of the circular spring (101),
(4) is fixed. This circular spring (101), (10
An air core bobbin (103) is fixed to the center of (2).
A winding coil (104) made of a thin copper wire of about 0.1 mm is wound around the outer circumference of the air-core bobbin (103).

FIG. 2 (a) is a perspective sectional view showing the structure of the movable head unit (100), and FIG. 2 (b) is a longitudinal sectional view thereof, wherein (101) and (102) are circular springs. , A movable head (3) at one end of the circular spring (101),
(4) is fixed. This circular spring (101), (10
An air core bobbin (103) is fixed to the center of (2).
A winding coil (104) made of a thin copper wire of about 0.1 mm is wound around the outer circumference of the air-core bobbin (103).

(105) is a permanent magnet made of rare earth cobalt, etc. (1
06) is a ball bead made of soft iron, and (107) and (108) are yokes made of soft iron.
The permanent magnet (105) is arranged in the inside, and the permanent magnet (105) is fixed to the yoke (108). These constitute a drive mechanism for the movable heads (3), (4). Reference numeral (109) is a cap, and (110) is a printed circuit board to which the lead wire of the winding coil (104) is connected.

3 (a) and 3 (b) show the circular springs (101), (10).
FIG. 2 is an enlarged plan view showing the configuration of 2). These two circular springs (101) and (102) are provided on the copper alloy plates (101A) and (102A) having a thickness of 0.08 mm as shown in FIGS. 3 (a) and 3 (b). By forming a large number of 101b) and (102a), soft and uniform elasticity is provided. Smallly formed parts (101B) and (102B) are fitted in the central part of the core, and an air core bobbin (103) with a coil is fixed therein. Also,
As shown in FIG. 3 (a), a long protruding piece (101a) with a notch is taken out from a part of the outer circumference of the circular spring (101), and the movable head (3), ( 4) is attached.

Now, as shown in FIG. 4, when the S and N poles of the permanent magnet (105) are provided above and below and a current flows through the winding coil (104), a force is applied in the direction of arrow A according to the left-hand rule of framing. Working, the air core bobbin (103) moves downward. At this time, the outer circumferences of the circular springs (101) and (102) are connected to the yoke (10
Although it is fixed to 7), it has a soft and uniform elasticity, so that the entire air-core bobbin (103) moves downward in proportion to the magnitude of the current.

Along with the movement of the bobbin (103), the movable heads (3) and (4) attached to the long protrusion (101a) of the circular spring (101) move in parallel in the downward direction A1. When the current flowing through the winding coil (104) is set in the opposite direction to the above case, the air-core bobbin (10
As indicated by arrow B, 3) moves in parallel in the upward direction, and the movable heads (3) and (4) move in parallel in the upward direction B1.

As can be seen from the above explanation, the movable head (3),
(4) moves vertically along the axial direction of the drums (7), (8), so that the tape and the movable head (3),
The sliding surface of (4) is always in full contact, and the FM of the magnetic surface of the tape
The signal can be picked up to the maximum and the tape on the outer peripheral surface of the head is not damaged.

FIG. 5 is a block diagram of an electric circuit showing the configuration of the tracking device of the present invention, in which the same reference numerals as those in the conventional example of FIG. 11 indicate the same or corresponding parts. Incidentally, the normal recording / reproducing fixed heads (1) and (2) are removed here, and accordingly, the number of windings of the rotary transformer (10) is reduced from four to two, and the normal reproducing head amplifier ( 11) has been removed.
Further, (14) is a head amplifier for special reproduction and normal reproduction, which is an amplifier equipped with a recording amplifier for recording.

In FIG. 5, (31) is an A / D conversion circuit for converting the envelope detection output voltage into a digital signal, and (32) is digital data for controlling the drive head by each timing input signal and mode output signal. A winding coil (104a), (10) that drives two movable heads (3), (4) in a microcomputer that outputs a signal.
b) Scan signal basic waveform generation ROM (32
a), (32e), tilt angle correction ROM (32b), (32f),
Optimal track movement ROMs (32c) and (32g) that correct the phase of the scanning signal with respect to the magnetic tape, and hill climbing correction ROM (32
d) and (32h), and a swing-back signal waveform generation ROM (32i) that swings back the movable heads (3) and (4) within a period in which they are not in contact with the magnetic tape. (32a), (33
b), (33c), (33d) are the above-mentioned microcomputer (3
2) D / A conversion circuits for converting the output signals corresponding to the respective output ports into analog signals, (34a), (34b) are the D / A conversion circuits (33a), (33b), (33c), An adder for adding the two analog signals output from (33d),
(35) is a sequence control circuit for performing sequence control in various playback modes.
a) and a control circuit (35b).

(36a) and (36b) are two erasable ROMs described later.
(39a), (39b) D / A conversion circuit for converting the digital signal read into an analog signal, (37) is a microcomputer for driving the two erasable ROMs (39a), (39b), (38a), (38a) 38b) are analog switches that are interlocked with each other, and position PLAY for special and normal playback, respectively.
There is a recording position REC. (39a), (39b)
Is a non-volatile memory and consists of a rewritable erasable ROM. (40) is a recording signal processing circuit.

Next, the operation of the above configuration will be described with reference to the signal waveforms of the respective parts shown in FIG.

The sequence control circuit (35) is shown in Fig. 6 (a).
The fixed head changeover flip-flop signal FF shown in FIG. 6 is input, and after being delayed by a predetermined amount in the delay circuit (35a), the movable head changeover flip-flop signal MVFF shown in FIG. 6 (b).
Is input to the microcomputer (32).

Now, assuming that a forward search reproduction of 5 times speed is performed as shown in FIG. 10, when this command is output from the sequence control circuit (35), the microcomputer (32) has a built-in ROM (32a) ... 5 out of (32i)
The ROM contents of the scanning signal basic waveform generating ROM (32a) for designating the ideal values of the scanning patterns of the double speed movable heads (3) and (4) are transmitted. The waveform signals sent from this scanning signal basic waveform generation ROM (32a) are (33a), (34a), (38a),
It is applied to the movable head drive winding coil (104a) through (23a) and (24a), and the movable head (3) takes the basic position of scanning on the track A1, that is, the locus of L2 in FIG. Is determined.

This operation corresponds to the operation indicated by the broken line in the part (a) in FIG. 6 (c).

At this time, the signal of the track A1 reproduced by the movable head (3) is envelope-detected by the envelope detection circuit (15), and the signal S converted into a digital signal by the A / D conversion circuit (31) is serially transmitted. Added to Micro Computer (32). Then, the microcomputer (32) sequentially compares and calculates the envelope detection signal S and the basic waveform of the selected scanning signal step by step, and a tilt correction ROM (32b) in which various correction values are prepared.
The one having the optimum inclination correction value is selected from (about 30 kinds are required), and the scanning signal obtained by adding the inclination correction signal by the adder (34a) is applied to the winding coil (104a). As a result, the inclination angle of the scanning locus of the movable head (3) is corrected as shown by the arrow in the part (a) of FIG. 6 (c), and this correction operation is performed by the head shown by the arrow a of FIG. This corresponds to the correction of the movement amount.

By the operation up to this point, the tilt angle of the recording track A1 and the scanning locus of the movable head (3) at the time of special reproduction coincide with each other as shown by the solid line in the part (a) of FIG. 6 (c).

Next, the optimum track moving signal for selecting a preselected track to obtain the optimum result at the time of forward search at 5 times speed is read from the optimum track moving ROM (32c), and the drive in which this moving signal is added is read. A signal is applied to the winding coil (104a) to cause the movable head (3) to scan over the optimum track. In this case as well, the envelope detection signal S is similarly added to the microcomputer (32), and the optimum track is selected from this level.

With the above operation, the movable head (3) scans almost the optimum state, that is, the track of L2, but the best position in the optimum track, that is, the position where the level of the envelope signal S becomes the maximum value. In order to track the camera, a so-called hill climbing correction is performed in which the movable head (3) is displaced in parallel with the scanning locus. This operation is a reproduction signal processing circuit (13)
Microcomputer (32) based on the vertical sync signal V-SYNC which is demodulated by V sync signal separated by V sync separation circuit (25).
The hill climbing correction ROM (32d) therein offsets the scanning track of the movable head and the recording track so that the serial envelope detection signal S becomes the maximum value.

This operation corresponds to the operation indicated by the broken line in the part (b) of FIG. 6 (d). As a result, in FIG. 10, the point X is accurately tracked and the center line of the recording track is scanned for one field period. This is equivalent to making a fine adjustment in the direction perpendicular to the video track.

Although the above description of the operation has been made on the movable head (3), the same applies to the movable head (4). In this case, the scanning signal basic waveform generation ROM (32e) and the tilt angle correction ROM (3
2f), optimum track movement ROM (32g), hill climbing ROM (3
2h), D / A conversion circuit (33c), (33d), adder (34d),
Analog switch (38b), LPF (23b), drive amplifier (2
The movable head (4) is driven by the operation of 4b), and its movement amount is as shown by an arrow b in FIG.

Next, when the movable head (3) finishes scanning the magnetic tape surface, and then the movable head (4) scans the magnetic tape surface, the movable head (3) does not come into contact with the tape surface and is in the air. Is moving in rotation. This field period,
In other words, the behavior of the movable head (3) during the field period during which the movable head (4) scans the magnetic tape surface is based on the envelope signal waveform during the previous traveling field period. (32i)
The optimum one (out of about 5 types is required) is selected and sent to the D / A converter (33a). This swingback signal waveform is
It is shown in the C part of FIG. If an improper swing-back signal waveform is selected as indicated by the broken line C, a large step is generated at the switching point of the MVFF signal, the movable head (3) is largely displaced, and noise is generated.

The swing-back signal waveform generation ROM prepared in advance in this way
When the movable head is driven while the drum is half rotating in accordance with the swing-back signal waveform of (32i), continuous smooth driving is performed as shown by the solid line in FIGS. 6 (c) and (d), and noise is generated. A stable 5 × speed search signal can be obtained.

As shown in FIG. 6, assuming that the number of steps of the microcomputer (32) in one field period is 256 steps, as shown in FIGS. 6 (c) and 6 (d), 0 of the microcomputer (32) is obtained. Between ~ 116 steps (1 / 30H
Z × 116/256 = about 15 msec) is driven to swing back the movable head in the selected fixed pattern, and during the remaining 117 to 256 steps, a comparison operation is performed with the envelope detection signal in the microcomputer (32). Inclination angle correction and hill climbing correction are applied so that the movable head travels accurately on the next recording track. The waveform of the swing-back signal for the next about 15 msec is selected according to the envelope detection signal data at this time, so that the playback signals of the movable heads (3) and (4) are connected almost continuously. Is driven.

A specific example of the above-mentioned microcomputer (32) is M50747 (8bit 8kbyte ROM).

 Next, the operation during normal reproduction will be described.

The normal reproduction operation is basically the same as the speed search reproduction operation described above, but since the tape speed at this time is 1 time, the movable heads (3) and (4) are the same as those of the speed search reproduction of 5 times speed. You don't have to move as big as sometimes. Head movement amount (a), (b) shown in FIG.
Is close to zero. Therefore, the movable head (3),
The drive signal waveform of (4) is as shown in FIGS. 6 (e) and 6 (f). At this time as well, the movable heads (3) and (4) are completely tracked according to the inclination angle and linearity of the video track of each tape recorded, so that a sufficient reproduction output can be obtained and the crosstalk between adjacent tracks can be achieved. It is possible to reproduce a high quality image with less.

 Next, the operation during recording will be described.

Since there is no reference signal on the tape during normal recording operation, there is no output from the envelope detection circuit (15). Therefore, the width, tilt angle, and linearity of the video track are correctly controlled by a standard recording tape, for example, a standard tape that accurately conforms to the VHS format format, and the VHS standard used by the tape manufacturer in the production process. Insert the tape and perform playback operation. The operation at this time is the same as the above-mentioned reproduction operation, and each ROM (32a), (32b), (32c), (32
The output signals of d) and (32i) are stored in the erasable ROM (39a). In addition, each ROM (32e), (32f), (32g),
Erasable ROM (39b) for output signals of (32h) and (32i)
To memorize. That is, the erasable ROM (39a),
The ideal drive signal waveform data of the movable heads (3) and (4) during the reproducing operation using the VHS standard tape is stored in (39b) prior to normal recording. Then, during the actual recording operation, these eraseable RO
The digital drive signal waveforms stored in M (39a) and (39b) are read out and converted into analog signals by the D / A conversion circuits (36a) and (36b), and analog switches (38a) and (3
The drive signal is applied to the winding coils (104a) and (104b) through the LPFs (23a) and (23b) and the high voltage amplifiers (24a) and (24b) via the REC position of 8b).

The eraseable ROMs (39a) and (39b) need only be written once during production, but if the VTR interior drifts after a long period of use, the ROMs (39a), (3
By rewriting 9b), it is possible to make a recording tape with an ideal format. From this point, it is most suitable for a dubbing machine that creates soft tape.

Further, the fixed head mounted on the drum in order to match the standard format required the mounting accuracy of 1 μm, but according to the present invention, the eraseable ROM (39
Since the correction is applied by the data written in a) and (39b), high mounting accuracy is not required and rough mounting is sufficient, so that the assembling property can be remarkably improved.

Further, since the internal configuration of the microcomputer (32) can be variously considered, it is not always necessary to have the configuration of the above embodiment.

In the above embodiment, the case of quintuple speed search reproduction has been described with the configuration shown in FIG. 1 to FIG. 6, but slow, stale, reverse reproduction, etc. can be handled by increasing the ROM in the microcomputer. it can. Further, although the movable heads (3) and (4) are configured to be moved by using the winding coils, any one can be used as long as the movable heads (3) and (4) can be moved by about ± 300 μm in the rotation axis direction of the drum.

The basic waveform generation ROM (3
2a), (32e), and (32i) are increased so that they can be selected more finely according to the envelope detection signal waveform, the amount of tilt correction is small, convergence can be achieved in a short period of time, and accuracy can be increased quickly. It is possible to obtain a tracking device that can eliminate noise and reproduce a completely noiseless image.

Note that, as an example of the memory circuit for storing the drive signal waveform, in the above-described embodiment, the erasable ROMs (39a) and (39b) which are the non-volatile memories are shown, but the memory element can be composed of general components.

Further, the two microcomputers (32), (37) shown in the above embodiment may be constituted by one microcomputer.

Further, the rotary drum is provided with a pair of movable heads, but the same effect as that of the above-described embodiment can be obtained even when three or more movable heads are provided.

[Effects of the Invention] As described above, according to the present invention, the movable head mounted on the rotary drum is automatically adjusted to maximize the level of the reproduced FM signal while the surface of the movable head is in surface contact with the magnetic tape during the reproducing operation. Since tracking control is performed, noiselessness during special playback such as speed search and normal playback
Improvement of C / N can be achieved. In addition, since the drive signal waveform during a good reproducing operation can be read during a recording operation and the behavior of the movable head can be accurately controlled, accurate recording conforming to the standard tape format can be performed. Therefore, special reproduction and normal recording / reproduction can be performed only by the movable head, and by reducing the number of heads, it is possible to suppress the occurrence of jitter due to the tape-tapping phenomenon and reduce the cost. Further, even if the mounting accuracy of the head is rough, it can be corrected by electrical control, so that the assembling workability can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a drum structure of a rotary 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 and a vertical section showing the structure of a head unit. Plan view, FIG. 3 (a),
(B) is an enlarged horizontal cross-sectional view showing the structure of a circular spring, FIG. 4 is a schematic vertical cross-sectional view of the principal part for explaining the operating principle of the head unit, and FIG. 5 is an electric circuit block diagram showing the structure of the tracking device. FIG. 6 is a signal waveform diagram for explaining a tracking operation, FIG. 7 is a perspective view showing a drum structure of a rotary head device in a conventional magnetic recording / reproducing apparatus, and FIG. 8 is an enlarged structure diagram of an actuator part of a movable head. FIG. 9 is an explanatory view of the operation principle of the bimorph type piezoelectric element, and FIG.
FIG. 11 is a block diagram of a specific electric circuit of the conventional automatic tracking device, which is a diagram for explaining the movement of the movable head on the tape pattern when performing the speed search operation at the double speed. (3), (4) ... movable head, (7) ... rotating head, (15) ... envelope detection circuit, (24a), (24)
b) …… Drive amplifier, (32), (37) …… Microcomputer, (32a), (32e) …… Basic waveform generation ROM,
(32b), (32f) …… Tilt correction ROM, (32c), (32g)
…… Optimum track movement ROM, (32d), (32h) …… Climbing correction ROM, (32i) …… Swing-back basic waveform generation ROM, (3
3a), (33b) …… D / A conversion circuit, (34a), (34b) ……
Adder, (35) …… Sequence control circuit, (36
a), (36b) …… D / A conversion circuit, (39a), (39b) ……
Erasable ROM, (100) …… Movable head unit,
(104a), (104b) ... Winding coil. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A rotary drum, a recording / reproducing movable head mounted on the rotary drum so as to be movable in parallel in the axial direction thereof, and the movable head being parallel to the axial direction of the rotary drum and adapted to supply current. An electromagnetic drive mechanism for moving the movable head, an envelope detection means for generating an envelope detection signal from the signal reproduced by the movable head, and a reference signal generated corresponding to the traveling speed of the recording medium, by the envelope detection signal. And a reference signal generated corresponding to the running speed of the standard recording medium which has been recorded by the above-mentioned calculating means are corrected and calculated by the envelope detection signal so that this envelope detection signal becomes maximum. A storage means for storing the signal is provided, and at the time of recording, based on the signal read from the storage means. The movable head is moved to a predetermined position by the electromagnetically controlled mechanism for recording and recorded, and at the time of reproduction, the movable head is moved and reproduced by the electromagnetically driven mechanism controlled based on the output signal of the arithmetic means. A magnetic recording / reproducing apparatus characterized by being configured.