JPH02235484A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve an S/N and to obtain high picture quality by driving a moving video head so as to be in matching with a track at special reproduction thereby picking up optimizing ly a signal recorded on a track. CONSTITUTION:In the case of the 3 fold speed mode recording, after an audio signal is recorded to the deep layer by using an audio head 4R as shown in figure, a video signal is recorded to the deep layer by a video head 36R with a delay of 1/3 period. The signal is recorded similarly by an audio head 4L at the succeeding half period and the video signal is recorded with a video head 36L with a delay of 1/3 period. Since the head width of the video heads 36L and 36R is coincident with the track width 19.3mum of the recording format in this case, the video tracks are recorded without nay gap and no overwrite is caused. Thus, the tape format is effectively utilized and the deterioration in the S/N due to overwrite is not caused. In the case of the 3 fold speed mode reproduction, the picture quality with excellent S/N is attained similarly.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a magnetic recording and reproducing device that can perform two or more types of recording and reproducing operations, such as a standard speed mode and a long-time speed mode, by changing the tape speed. It is related to.

(Prior Art) Fig. 2 is a plan view showing an outline of a rotating drum device in a conventional magnetic recording/reproducing device, for example, a VHS IFIVTR.
is a standard mode video head, 6L., mounted on a rotating drum L at intervals of 180'. 6R is a 3x mode video head added to the rotating drum L at 180° intervals, and 7, 2L, 6R and 2R . 6L is composite and integrated. 4L and 4R are audio heads similarly attached to the rotating drum 1 at intervals of 180', and record audio signals deep into the magnetic tape. Each head 2L. 2R, 4L. 4R. 6L. A specific numerical example of the head width of 6R and the mounting dimension to the rotating drum l, that is, the height difference, is as shown in FIG. 2R-
Hesode width 48n, height difference Q% 7d 4L. 4R head width 27711, step 58.5, 11111, head 6
L, 6R head width 33-, step 1. It's Spya.

Of course, means for selectively operating each head is provided separately. Next, the operation of the above configuration will be explained. The tape pattern and passing position of each head during standard mode recording are as shown in Figure 4 (al, (b)).In the standard mode (3.335C11/sec in VHS format), first the audio head 4R After audio is recorded deep on the magnetic tape, video is recorded on the surface by the video head 2L with a delay of 173 cycles (120°).The next half cycle is recorded in the same way by the audio head 4L.
It is recorded to the video by Nodo 2R with a delay of 173 cycles.
At this time, the head width of video heads 2L and 2R is 48p.
m, a gap (guard band) of lOIrm occurs for the track width of 587 m on the magnetic tape, as shown in Figure 4+81, and there is still space for recording. Next, in long-time mode (3x speed in VHS format),
First, after the audio is deeply recorded with Audio Hefdo 4R,
A video is recorded on the surface by the video head 6R after a delay of 1/3 'u1<120°>. The next half cycle is similarly recorded by the audio head 4L and then recorded by the video head 6L with a delay of 173 cycles. At this time, since the video head width 6R and 6L is 33μ,
As shown in FIG. 4 1bl, the track width is 19. 3
13.7- overflows from u, and is overwritten in the next field, thus contaminating the next field.

The above is about the recording mode, but the same applies to playback. Next, play still images, slow playback, double speed playback,
This section describes the operation of special playback such as high-speed picture search (speed search). Here, heads 2L, 2
If the width of R is 48 tm and the guard band IOJ@ is drawn, the diagram will become complicated and difficult to understand, so the basics of the mechanism will be briefly explained using FIGS. 5 and 6. FIG. 5 shows the relationship between the trajectory of the video head on the magnetic tape 20 and the speed at which the magnetic tape 20 sends phrases, where the arrow 2l shows the standard running direction of the tape 20 and the arrow 22 shows the head driving direction. Also, the diagonal line in the figure indicates the head trajectory during tape running, such as during fast forwarding, which is written in the figure. In this way, the trajectory of the head on the tape 20 is determined by the combination of the movement of the head and the movement of the tape 20, and therefore changes depending on the speed and direction of the tape 20 and the head. Therefore,
The state of deviation of the reproducing head from the recording track changes depending on the speed of the tape 20 during reproduction. Furthermore, since the azimuth recording is performed at an angle, the playback output is determined by how much of a deviation is traced over the track where the azimuth of the hendogyasop is lost. Now, as an example of special playback,
The case of still playback will be explained using Figure 6. Video head 2L. 2R. 6L, 6R cross the recording track diagonally, and A, . 82 heads play the same part. FIG. 6 Tal, (b) shows the head trajectory 23 and the reproduction output envelope signal at that time, respectively, and the output when the head 2L reproduces the recording track A (shown as A8 in the bl figure, track Bl head 2
The output when R is reproduced is shown as B in the (kl) diagram, and this output is repeated. 23 is the head trajectory at this time. In addition, Fig. 6 (cl, (dl) indicates other cases, and the playback output in this case is At-B+-^, -^, -4 3
, −*Q ,. AI indicates the output when head 2R plays track ^1. Looking at the reproduced output envelope signals in these two cases, as shown by arrow 24, there is a valley where the envelope signal level is extremely reduced to zero. Noise occurs in this valley because there is no reproduction envelope signal, and noise occurs in a part of the still reproduction screen, making it unsightly. For this reason, generally, as shown in Figure 6(a), '(fl), a head having a head width wider than the track width (for example, a head having a head width of 70μ for a track width of 58μ, or It is customary to use a head with a head width of 33n for a track width of 19.37l to make the valley of the envelope signal shallow.However, in this case too, because the head width l is wide, the adjacent The track signal also jumps up, forcing S/N deterioration due to crosstalk components.

Further, as shown in FIG. 2, it is also possible to perform a still reproduction operation using one side of the composite head (for example, opposing heads with the same azimuth, such as heads 2L and 6L). That is, as shown in Fig. 6 (gl.Thl), when the same field is alternately reproduced using heads 2L and 6L, the envelope {Ll<a+. , there is no dropout of the envelope signal, and no noise occurs on the still side.
5 is the trajectory of the head 2L, and 26 is the trajectory of the hend 6L. Therefore, in the current VTR, as shown in Fig. 6 (gl, (
The mainstream is to operate like a hl, but since it is desirable for the head 6L to have a wider head width in this case, the head width is usually set to 33μ at the expense of crosstalk interference during recording and playback. The head width is wider than 19.3μ, which is the optimum width for recording and playback, except for special playback such as still and slow play. [Problems to be Solved by the Invention] As mentioned above, in conventional VTRs, the head width is narrower than the video track width 58n of the predetermined format during standard mode recording and playback, and the head width is narrower than the video track width of the predetermined format during long time mode recording and playback. Video track width of 19
．． Since it is configured to be wider than 3 Jllll, a noise-free screen can be obtained during special playback such as slow and still modes, but when recording and playing back in standard mode, the S/N ratio is low because sufficient signal cannot be obtained. The head operates in a state where the magnetic field cannot be sufficiently increased, and when recording and reproducing in a long-time mode, crosstalk interference occurs between adjacent tracks, increasing noise and deteriorating the S/N ratio. Therefore, a magnetic recording and reproducing device with high image quality is obtained. I couldn't do it. This invention was made to solve the above-mentioned problems, and it is possible to perform recording and reproducing operations with a sufficient S/N during normal recording and reproducing in both standard mode and long-time mode. It is an object of the present invention to provide a magnetic recording/reproducing device which can perform special reproduction operations with a sufficient S/N ratio even during special reproduction.

[Means to solve the problem]

The magnetic recording and reproducing device according to the present invention is fixed to a rotating drum and has a head width that matches the recording track width of the magnetic tape in each mode during normal recording and reproducing,
A plurality of fixed video heads are selectively operated according to the mode during normal recording and playback, a movable video head is installed on a rotating drum so that it can move in the direction of its rotational axis, and a movable video head is moved to the magnetic tape recording track during special playback. This device is equipped with a means to control the drive so that it traces in accordance with the following. [Function] In the present invention, during normal recording and playback, recording and playback is performed using a fixed video head with a head width that matches the track width, and the video track is recorded and played back without any gaps, and overwriting on adjacent tracks is prevented. Does not occur. Also, during special playback, the movable video head matches and traces the center of the recording track. (Example) Hereinafter, an example of the present invention will be explained with reference to the drawings.
The figure shows a rotating drum device according to this embodiment, 32L.
32R is a standard mode fixed video head attached to a rotating drum L at 180° intervals, and has the same head width as the standard mode recording track width (58zs in VHS format). 36L and 36R are rotating drums. 180 to l
The fixed video heads for 3x mode are installed at 3x mode intervals, and the head width is the same as the recording track width for 3x mode (VH
In the S format, each video head 32L, 36R and 32R. 36L is integrated into a composite structure, and can be selectively operated according to the mode, as in the past. audio hend 4
L. 4R is the same as before. Further, Ml+'Mz is a movable video head, which is provided on the rotating drum 1 at an interval of 180 degrees. is provided so as to be movable several tens of microns in the axial direction of the rotating drum. or,
The movable video head M l +M”* is a head dedicated to special playback, and its head width is 1 recording track width in 3x mode.
The azimuth is less than twice that of 9.3μ, specifically 31. Figure 7 shows the head width and steps/differences of each head,
The head width is as described above, and the step is head 4R. 4
L is 58.5B, hesode 32R, 32L is 0, hend 3
6R and 36L are 19.5μ, and Hesid M+ and L are movable. Next, the operation of the above configuration will be explained. The tape pattern trajectory of each head during standard mode recording and playback is shown in Figure 8+al. First, after the audio signal is deeply recorded with AudioHend 4R, 1/3 Ji!
] After a delay, the video signal is recorded on the surface layer by the video head 32L. In the next half cycle, after being deeply recorded to the audio head 4L, after a delay of 173 cycles, the video head 32
It is recorded on the surface layer in R. At this time, VideoHend 32L,
Since the 32R head width matches the track width of the recording format, it records to the full 58M. As a result, video tracks are recorded without gaps and are not overwritten, making effective use of the tape format and
/N No deterioration occurs. , Hefdo 4R, 4L, 32R. 32L, the recorded track can be traced in the same way as when recording, and a reproduced image with a good S/N ratio can be obtained. Next, when recording in 3x mode,
As shown in FIG. 1, after the audio signal is recorded in the deep layer by the audio head 4R, the video signal is recorded in the surface layer by the video head 36R with a delay of 1/3 of a turn. Similarly, the next half cycle is recorded by the audio head 4L and then recorded by the video feed 36L with a delay of 1/3 cycle.

At this time as well, the video head 36L. The head width of 36R is the track width of the recording formant 19. 3 ls, the video track is recorded without gaps and no overwriting occurs. Therefore, the tape format can be used effectively, and S/N degradation due to overwriting does not occur. Similarly, image quality with good S/N can be obtained during 3x mode playback.

As mentioned above, in both the standard mode and the 3x mode, video signals are recorded and played back with full energy because they are recorded and played back using a head with a head width that matches the track width of a given recording format. Furthermore, crosstalk components from adjacent tracks do not occur at all, making it possible to increase the S/N ratio and produce high-quality VTRs.
is obtained. However, video heads 3'2L, 32R.
Is the special playback image noisy with only 36L and 36R? Therefore, movable video heads Ml+M2 are provided. FIG. 9 shows a cross section of the rotating drum device, in which 8 is a fixed drum supporting a drum motor 12 and a rotating shaft 14, and a rotating drum 1 is provided opposite to this fixed drum 8 and integrally with the rotating shaft 14. 11 is a slip ring provided on the rotating shaft 14, 10 is a brush that contacts the slip ring 11 to supply current, and 13 is a rotary transformer. Reference numeral 100 designates a movable special reproduction head unit, of which two are provided. The head unit 100 and the upper part of the low retransmission l3 are fixed to the rotating drum 1, and the rotating drum l is rotated by the rotational operation of the drum motor l2. axis l4
It rotates at a constant speed of 1800rps+. Movable head Ml. ? Io is attached to head unit 10G. FIG. 10 (al. (bl shows a perspective sectional view and a longitudinal sectional front view of the hend unit 100, 101 and 102 are circular springs, and one end on the circumference of one of the circular springs 101 has a movable head 1 or M ■ is fixed. Also, the circular spring 101.
An air-core bobbin 103 is bonded to the center of the air-core bobbin 102, and a coil 104 made of a thin copper wire of 0.1 φ wound 250 times is provided around the outer periphery of the air-core bobbin 103. A permanent stone 105 made of rare earth cobalt is arranged inside the bobbin 104, and a pole piece 106 made of soft iron is provided above it. 107 is bobbin 1
Yoke provided around 03, 1.09 is yoke 10
7 is a cap provided on the top, 110 is a coil 104
This is a printed circuit board for extracting the data to the outside.

Figure 11 (al. (bl) shows the details of the circular springs 101, 102. The circular springs 101, 102 are made of a beryllium copper plate with a thickness of 0.08 m and are provided with many slits to provide stable elasticity. In addition, a small Noryl molded product is fitted and fixed in the center of the circular springs 101 and 102, and an air-core bobbin 103 with a coil 104 is glued therein.In this way, the circular springs 101 and 102 The air-core bobbin 103 is glued and fixed in the yoke IO, 7 by gluing or fitting as shown in FIG. 10. That is, the circular spring 1
01 and 102 are fixed to the yoke 107, and when the air core bobbin 103 moves as a whole, the movable head MI+h
The only movement is up and down. FIG. 12 is a partially enlarged cross-sectional view of the rotating drum device, and FIG. 13 shows the configuration of the drive section of the rotating drum device, and the operation will be explained with reference to these drawings. A circular spring 101 as shown in FIG.
．． The outer periphery of 102 is fixed to the yoke 107, but a long piece with a notch is taken out from a part of the outer periphery of the circular spring lot, and a movable video head gate, or M8, is attached to the tip of the long piece. A permanent magnet 105 is provided inside the air-core bobbin 103 and is fixed to a yoke 107. ing. Now, as shown in FIG.
are provided with N and S poles, and when a current is applied to the coil 104 via the brush IO and the slip ring l1, Fleming's left hand rule (middle finger...current, index finger...magnetic field, thumb...force) is applied. ), a force acts in the direction of arrow A, and the air-core bobbin 103 moves downward. At this time, the outer peripheries of the circular springs 101 and 102 are fixed to the yoke 107 but have soft and uniform elasticity, so the bobbin 103 moves downward in proportion to the magnitude of the current. For this reason,
Movable video belly button Ml+ M! also moves downward. On the other hand, if the current flowing through the coil 104 is reversed, the bobbin 103 will move upward. Movable video hefdo M,
, Because the VIE moves up and down along the drum axis, the sliding surfaces of the movable video head Ml+ Mz and the magnetic tape are always in full contact, maximizing the pink-up of the FM signal on the tape magnetic surface. Moreover, there is no damage to the tape due to the edges of the outer peripheral surface of the movable heads M1M8.

In addition, in the drive section shown in FIG.
Based on the capstan frequency oscillator (FG) signal from the capstan frequency oscillator (FG) signal from the control head 28 and the control (CTL) signal from the control head 28, the movable video head MI+M! The amount of movement is calculated, and the output is applied to the coil 104 via the adder circuits 122, 123, filter circuits 124, 125, gain adjustment circuits 126, 127, and current amplifiers 128, 129, and via the plush 10 and slithop ring 11. , drives the movable head Ml+ Mt. That is, the movable hesode MI
The position of the video track with respect to the rotation plane of +Mt is detected by the control signal and the FC signal of the main stand 27 that effectively divides the control signal, and the movable head Ml+Mt is driven in the vertical direction in accordance with this. Note that arrow 29 indicates the tape running direction, 30 indicates a +6° azimuth video track, and 3l indicates a control signal recorded on the magnetic tape 20. Also, when the playback speed of the magnetic tape 20 is faster than the reference speed during normal playback, the 7th Ml. Mg
A control current is obtained to displace the movable head Ml, L downward from the basic head position at the reference speed along the rotation axis l4, and when the playback speed is slower than the reference speed, the movable head Ml, L is moved from the reference add position along the rotation axis 14. to obtain the control current that causes the upward displacement. With the above configuration, it is possible to calculate the position of the video head with respect to the video track at any tape running speed, and by correcting this, it is possible to accurately trace the l-field period. Therefore, during special playback, the standard mode (track width 587II.
) and long-time mode (track width 19.31 Im), a state in which no noise is generated can be maintained, and the envelope signal waveform at this time is as shown in FIG. 6 fhl.

In the above embodiment, two or more circular springs 102 may be provided, but it is necessary to select one with high elasticity and good reliability. Further, although a large number of slits are provided in the circular springs 10l and 102, the structure is not limited to this; it is also possible to provide slits radially or to change the plate thickness. Further, although the rotation and parallelism with the axis l4 were maintained using the circular springs 101 and 102, the parallelism was maintained only with the circular spring 101 due to a structure in which one end side of the bobbin 103 was slidably held by three or more circular springs 101. It is also possible to keep it. Also, although the coil 104 is provided on one end side of the bobbin 103,
The distance between the circular springs 101 and 102 is preferably large, so for example, the coil 104 is placed in the center of the bobbin 103, and the circular spring 101 is placed between the coils 104.
, 102 may be provided. Further, in the above embodiment, an example of VHS system 2〇IFIVTH is shown, and deep recording system audio heads 4L and 4R are provided, but the present invention can also be applied to a VHS system monaural audio VTR in which only video signals are recorded and played back using a rotating head. can be applied,
It can also be applied to β-method VTRs. Also, video belly button 32L
, 32R, 36L, 36R head width is 58μ and 1
9. 3 pm, but there may be an error of several microns due to manufacturing, especially for the 3x mode video hesode 36R, 3
In the case of 6L, it may exceed 201, but this degree of error is within the permissible range. (Effects of the Invention) As described above, according to the present invention, during normal recording and reproduction, recording and reproduction are performed using a fixed video head whose head width matches the track width of each speed mode.
There are no unrecorded/reproduced portions on the track, no space talk, etc., and the S/N ratio is improved, resulting in high image quality. Furthermore, since the movable video head is driven to match the track during special playback, the signal recorded on the track can be boosted to the maximum extent, and the S/N ratio can also be improved.

[Brief explanation of drawings]

FIG. 1 is a plan view of a rotating drum device according to the present invention, and FIG.
Figure 3 is a plan view of a conventional rotating drum device, Figure 3 is a diagram showing the head width and mounting step of each conventional head, Figure 4 is a diagram showing the relationship between the tape track and head passing position of the conventional device, and Figure 5
6 is a diagram showing the relationship between the tape running speed and the head trajectory, FIG. 6 is a diagram showing the relationship between the head trajectory and playback output during still playback, and FIG. 7 is a diagram showing the head width and mounting step of each head according to the present invention. FIG. 8 is a diagram showing the relationship between the tape track and the head passing position according to the present invention, FIG. 9 is a longitudinal sectional front view of the rotating drum device according to the present invention, and FIG.
bl is a perspective sectional view and a vertical sectional front view of the hend uni-soto according to this invention, FIG. 11 is a plan view of a circular spring according to this invention, FIG. 12 is a partially enlarged sectional view of a rotating drum device, and FIG. FIG. 2 is a configuration diagram of the head driving section. l... Rotating drum, 10... Brush, II... Slip ring, l2... Drum motor, 14... Rotating shaft, 20... Magnetic tape, 27... Capstan, 28...・・Control head, 32L, 32R・・
・Fixed video head for standard mode, 36=L, 36R・
...Fixed video head for 3x mode, l00...Movable special playback head unit, 120...Pattern generation circuit, 121...Microcomputer, Ml+ Mt
...Movable video head ● Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa Figure 2 Figure 3? :5pm 1'W/ , N12 Figure l Figure 8 (Figure a) Figure 4 (Figure a (Figure b)

Claims (1)

[Claims] In a magnetic recording/playback device that performs normal recording/playback operations and special playback operations in two or more types of tape speed modes, the tape is fixed to a rotating drum and matches the recording track width of the magnetic tape in each tape speed mode during normal recording/playback. A plurality of fixed video heads, each having a head width of 300 mm, are selectively operated according to the mode during normal detailed recording and playback, a movable video head is installed on a rotating drum so that it can move in the direction of its rotation axis, and a movable video head is used for special playback. 1. A magnetic recording/reproducing apparatus comprising means for driving and controlling a head so as to match and trace a recording track of a magnetic tape.