JPS6122379B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention provides a method for winding a tape guided by at least one pair of tape guides around the outer circumferential surface of a head disk which is rotatably driven and has a head provided on its outer circumference. The present invention also relates to a recording and reproducing apparatus in which recording and reproducing are performed by bringing this tape into contact with the head, and is particularly suitable for application to a recording and reproducing apparatus such as a VTR using a high-frequency direct FM recording system.

Prior Art Among helical scanning VTRs, high-frequency direct FM recording VTRs used in broadcasting stations and production studios have a head disk that has editing and read-after-write functions. A large number of magnetic heads, for example six, are provided on the outer peripheral surface.

That is, as shown in FIG. 7, a video head 2, a sync head 3 for recording vertical synchronizing signals, and a video erasing head 4 are arranged on the outer periphery of the head disk 1.
A sync erase head 5, and a confidence sync head 7 for simultaneous reproduction are provided.

The video erase head 4 and the sync erase head 5 are located 120 degrees ahead of the video head 2 and the sync head 3 in the rotational direction of the head disk 1 (clockwise in FIG. 7), and 2 and sink head 3
On the other hand, the confidence video head 6 and the confidence sink head 7 are located at positions delayed by 120° in the rotational direction of the head disk 1, respectively.

Furthermore, the sync head 3, the sync erase head 5, and the confidence sync head 7 are each located at a position 30 degrees advanced in the rotational direction of the head disk 1 relative to the video head 2, video erase head 4, and confidence video head 6. It is provided.

Therefore, the previously recorded vertical synchronization signal is first erased by the sync erase head 5, a new vertical sync signal is recorded on the magnetic tape 10 by the sync head 3, and this signal is sent to the confidence sync head. 7 and simultaneously reproduced.

For video signals other than vertical synchronization signals,
First, it will be erased by the video erase head 4, a new signal will be recorded by the video head 2, and simultaneously reproduced by the confidence video head 6.

Note that the above video head 2 and video erase head 4
and confidence video head 6 are disposed offset in the axial direction, that is, approximately in the width direction of magnetic tape 10, on the outer circumferential surface of head disk 1 with respect to sync head 3, sync erase head 5, and confidence sync head 7, respectively. There is.

The magnetic tape 10 also includes a pair of tape guides 8,
9 is wound around the outer peripheral surface of the head disk 1 over a range of approximately 300°. The running direction of the magnetic tape 10 is opposite to the rotating direction of the head disk 1, and is configured to run counterclockwise with respect to the head disk 1.

In such a VTR, the six heads 2, 3, 4, 5, 6, and 7 are each held in a state in which they protrude slightly from the outer peripheral surface of the head disk 1, for example, by about 100 μm, and the magnetic tape 10 is Since a magnetic layer is formed on the surface of a polymer film, it has elastic properties.

Therefore, when the head disk 1 rotates at a high speed with respect to the magnetic tape 10 running at a relatively low speed, the heads 2, 3, 4, 5, 6, and 7 partially move the magnetic tape 10 as shown in FIG. It comes into sliding contact with the magnetic tape 10 while being deformed into a chevron shape.

This chevron-shaped deformation of the magnetic tape 10 continues until the position P where the magnetic tape 10 separates from the outer peripheral surface of the head disk 1. That is, in the section from when the magnetic heads 2, 3, 4, 5, 6, and 7 come into contact with the magnetic tape 10 to point P where they separate from the magnetic tape 10,
Frictional work is performed on the magnetic tape 10. Therefore, the mechanical influence that the magnetic tape 10 receives from the heads 2, 3, 4, 5, 6, and 7 changes before and after point P.

In addition, in the section where the magnetic tape 10 is wound around the outer peripheral surface of the head disk 1, the magnetic tape 10 is subjected to tension in its length direction, and since the magnetic tape 10 is bent in an arc shape, As shown in FIG. 8, a normal force F is applied to the radially inner side of the head disk 1. Therefore, due to this normal force F, the mountain-shaped deformation of the magnetic tape 10 is quickly recovered.

Problems to be Solved by the Invention However, in the section between point P and point Q (the point where the magnetic tape 10 is in contact with the tape guide 8), the magnetic tape 10 is stretched in a straight line. , Therefore, the normal force F is no longer applied to the magnetic tape 10. In other words, recovery from the mountain-shaped deformation will be delayed in this section. Due to these causes, the magnetic tape 10 causes string vibration between points P and Q.

Further, as shown in FIG. 7, in this VTR, the head disk 1 rotates clockwise at high speed, and as the head disk 1 rotates, the outer peripheral surface of the head disk 1 and the magnetic tape 10 are rotated.
Air 12 is introduced between the head disk 1 and the magnetic tape 10, and the magnetic tape 10 runs at a relatively low speed on the outer peripheral surface of the head disk 1 through this air layer. And this air 1
2 will be discharged near point P.

As shown in FIG. 9, at this discharge position, a negative pressure area lower than atmospheric pressure is generated between the outer peripheral surface of the head disk 1 and the magnetic tape 1, and in this area, atmospheric pressure As a result, the magnetic tape 10 protrudes radially inward from the head disk 1.

This phenomenon is known as a pressure spike phenomenon, and as a result of this, the heads 2, 3, 4, 5, 6, and 7 hit the protrusion 11 of the magnetic tape 10, causing the magnetic tape 10 to P point and Q
There will be further vibration in the section between the two points.

Magnetic tape 10 caused by such causes
The string vibration in the section between point P and point Q of
0 will cause stretching vibration in the length direction in this part.

Therefore, the time axis of the video signal is expanded or contracted, and as shown in FIG. Image disturbances corresponding to the vibrations occur. Therefore, the reproduced image becomes very unsightly, which has become a big problem.

In view of the above-mentioned points, the present invention provides a recording and reproducing apparatus which is free from the possibility that vibrations may occur in a portion of the magnetic tape and cause image disturbances.

Means for Solving the Problems The present invention provides a method for winding a tape guided by at least one pair of tape guides around the outer circumferential surface of a head disk which is rotatably driven and has a head on its outer circumference. In a recording and reproducing apparatus that performs recording and reproducing by bringing a tape into contact with the head, the tape is positioned at a position where the head leaves the tape, and the tape extending from the position at which the head leaves the tape is positioned in the at least one pair of tape guides. A plate is provided at a predetermined distance and approximately parallel to the tape between a tape guide that guides the head at a position closest to the tape guide, and vibration of the tape is generated when the head leaves the tape. The recording and reproducing device was configured to prevent this.

Effect: Therefore, the tape between the position where the head separates from the tape and the position of the tape guide is given a damping effect by the plate which gives a squeezing effect to the tape in this part, so the tape in the above part of the tape is Transverse vibrations are prevented, and as a result, longitudinal vibrations of the portion of the tape in contact with the head disk are not induced. Therefore, image distortion can be reliably prevented.

EXAMPLE The present invention will be described below using a high-frequency direct FM recording method.
An embodiment applied to a VTR will be described with reference to FIGS. 1 to 6.

In this embodiment, in order to prevent string vibration of the magnetic tape 10 in the section between the points P and Q, a squeeze plate 30 is placed parallel to the magnetic tape 10 in this section, and at a distance of several microns. are arranged in a fixed manner. Note that this squeeze plate 30 is formed integrally with the tape guide 8 in a block shape. The surface of the portion of the plate 30 facing the magnetic tape 10 is sufficiently lapped to have a mirror-like surface.

By arranging the squeeze plate 30 in contact with the magnetic tape 10 in this way, the magnetic tape 10
When the gap (gap) h between the squeeze plate 30 and the magnetic tape 10 changes due to the vibration of ^zero , from Reynolds' equation, as shown in FIG. x-B) A dynamic pressure is generated. Here, μ is the viscosity coefficient of air, t is time, δh/δt is the rate of change in voids,
x is the coordinate of an arbitrary position in the longitudinal direction of the magnetic tape 10 measured from the end of the squeeze plate 30, and B is the length of the squeeze plate 30. Now, if the effective area of the surface of the squeeze plate 30 facing the magnetic tape 10 is S, then a drag force F of F=∫ ^s Pds will move against the magnetic tape 10.
That is, the magnetic tape 10 receives an air dump effect, and its own string vibration is prevented. As a result, local disturbances in hue on the playback screen are removed.

Note that the squeeze plate 30 is not limited to that shown in FIGS. 1 and 2, and may have an inclined surface 31 at one end, for example, as shown in FIG. 4A, or as shown in FIG. 4B. like,
The distance between the magnetic tape 10 and the squeeze plate 30 may be changed sequentially, or the squeeze plate 30 may be divided into two parts in the height direction of the tape guide 8, as shown in FIG. 4C. Alternatively, the squeeze plate 30 may span the entire width of the magnetic tape 10 as shown in FIG. 4D, or the squeeze plate 3 may span the entire width of the magnetic tape 10 as shown in FIG. 4E.
0 may be removed from the portions corresponding to the magnetic heads 2, 3, 4, 5, 6, and 7 in the width direction of the magnetic tape 10. Alternatively, the surface of the squeeze plate 30 may be formed into a curved surface with a gentle curvature, as shown in FIG. 4F.

FIGS. 5 and 6 show an example in which the squeeze plate 30 extends over the entire width of the magnetic tape 10, and a portion corresponding to the magnetic head is cut out. That is, the squeeze surface 42 of the squeeze plate 30 has the heads 2,
4, 6, and horizontal grooves 43, 44 at heights corresponding to the heads 3, 5, 7.

With this configuration, the squeezing effect can be exerted over the entire width of the magnetic tape 10, and the squeeze surface 42 of the squeeze plate 30 can be used as the head disk 1.
This makes it possible to bring them very close to each other.

Although the present invention has been described above with reference to Examples, the present invention is not limited to the above-mentioned Examples, and various modifications can be made based on the technical idea of the present invention.

For example, the above embodiment uses the present invention as a high-frequency direct
Although the present invention is applied to an FM recording type VTR, the present invention can also be applied to various other helical scan type recording and reproducing apparatuses.

Further, in the above embodiment, six magnetic heads are provided on the outer peripheral surface of the head disk.
Even if a head disk is not necessarily provided with six magnetic heads, the present invention allows for example, when one magnetic head is tracing a magnetic tape, at least one other head moves away from the magnetic tape. It is also effective for VTRs that cause tape vibration.

Effects of the Invention As described above, in the present invention, a plate is disposed between the position where the head leaves the tape and the tape guide, and a squeezing effect is given to the tape between these positions. is subjected to a damping effect and oscillation is suppressed. Therefore, there is no fear that longitudinal vibrations will be induced in the tape at the portion where it contacts the head disk, causing image disturbance.

Furthermore, since the plate does not come into contact with the tape, there is no risk of damaging the tape, and it also has the effect of reducing the driving force of the tape.

[Brief explanation of the drawing]

Figures 1 to 6 show how this invention can be applied to high frequency direct
This shows an example applied to an FM recording system VTR. Figure 1 is a plan view of the main parts of the above VTR, Figure 2 is a perspective view of the same as above, Figure 3 is an explanatory diagram of the dynamic pressure acting on the tape, and Figure 3 is an illustration of the dynamic pressure acting on the tape. 4A to 4F and FIG. 5 are perspective views of the main parts of the above VTR showing a modification of the above embodiment, and FIG. 6 is a plan view of the main parts of the above VTR corresponding to FIG. Also, Figures 7 to 10 are from the same VTR as above.
7 is a plan view of the main parts of the same VTR, FIG. 8 is an explanatory diagram partially enlarged from FIG. 7, and FIG. 9 is an explanatory diagram partially enlarged from FIG. 7. , FIG. 10 is an explanatory diagram of the disturbance of the video of the same VTR. In the symbols used in the drawings, 1...head disk, 2...video head, 3...sync head, 4...video erase head, 5...sync erase head, 6...confidence video head, 7...confidence sync head. , 8...tape guide, 1
0... Magnetic tape, 30... Squeeze plate.

Claims (1)

[Scope of Claims] 1. A tape guided by at least one pair of tape guides is wound around the outer peripheral surface of a head disk which is rotatably driven and has a head provided on its outer peripheral portion, and this tape is attached to the head. In the recording and reproducing apparatus, the head is placed in contact with the tape at a position where it leaves the tape, and one of the at least one pair of tape guides extends from the position where the head leaves the tape and the tape is placed at a position closest to the position where the head leaves the tape. A plate is provided at a predetermined distance from and substantially parallel to the tape between the head and a tape guide that guides the head, and is configured to prevent vibration of the tape when the head leaves the tape. Recording and playback device. 2. The recording/reproducing apparatus according to claim 1, wherein the plate is supported by the tape guide. 3. The recording/reproducing apparatus according to claim 1, wherein the plate extends over the entire width of the tape in the width direction.