JPH0316010A - magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing device, and particularly to a magnetic recording and reproducing device suitable for reducing tape vibration.

[Conventional technology]

A VTR device generally has a rotating head, and performs recording and reproduction by scanning the magnetic tape and the rotating head relative to each other. In order to maintain constant contact between the head and the tape, a fixed drum or a rotating drum is disposed coaxially with the rotating shaft of the rotating head, and the tape is wound around the drum surface.

The head is made to protrude slightly from the outer peripheral surface of the drum.

The tape is wound around the drum while being guided by a guide member that positions the tape in the width direction.

Therefore, the tape is only tensioned between the drum and the guide member.

Since the head performs recording and playback while rotating, the tape enters the part where it begins to make contact with the drum every time it rotates. After recording and reproducing a predetermined length, the drum separates from the tape at the point where the tape and drum end contact. When the head plunges into the tape, the head slightly protrudes from the outer circumferential surface of the drum, so it has the effect of lifting the tape by the amount of this protrusion. After the head passes, the tape comes into contact with the drum surface again, so that an out-of-plane deformation is applied to the tape during the time the head passes. The same applies when the head separates from the tape. This force that deforms the tape in an out-of-plane direction becomes a tension force that vibrates the tape stretched between the drum and the guide member, causing tape vibration. This tape vibration may cause noise or
This causes speed fluctuations in the running direction of the tape, causing a distortion of the image on the screen called jitter. In conventional devices, no consideration was given to means for solving these problems.

Regarding the contact between the tape and the drum, for example, Japanese Utility Model Application Publication No. 148757/1983 can be cited. [Problems to be Solved by the Invention] The above conventional technology focuses on ensuring good contact between the head and the tape and ensuring the necessary recording/playback characteristics. No particular consideration was given to induced tape vibration. This is partly because the main causes of noise and video jitter caused by tape vibration were unknown.

An object of the present invention is to provide a highly reliable magnetic recording and reproducing device that reduces tape vibration, which is the main cause of the noise and image jitter. [Means for Solving the Problems] The above object is achieved by reducing the force for deforming the tape in an out-of-plane direction when the head enters or leaves the tape.

In order to reduce this tape deformation force, it is sufficient to reduce the amount of protrusion of the head from the outer circumferential surface of the drum, but simply reducing the amount of protrusion will make the contact between the head and tape unstable and result in poor recording.・There will be an inconvenience that playback will not be possible. In order to maintain good contact between the head and the tape, a predetermined amount of protrusion from the drum is required, so this is first ensured. Tape vibration is caused by periodic fluctuations in tape deformation force, so in order to reduce this periodic fluctuation force, a constant deformation force is applied to the tape at all times when the head enters or leaves the tape. Reduces the variation in deformation force.

Through the above means, the objective will be achieved.

[Effect]

In order to reduce fluctuations in tape deformation force, minute protrusions are provided on the outer peripheral surface of the drum. The height of the protrusion is set slightly lower than the height of the head. The tape is always in contact with the protrusion. As a result, when the head enters or leaves the tape, the force of the head pushing up the tape is reduced, tape vibration is significantly reduced, and noise and image jitter can be improved.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows an embodiment of the present invention. This embodiment includes a rotary head 3 that performs magnetic recording and reproduction, a rotary drum l that rotates integrally with the rotary head, a drive motor 6 that rotates the rotary head, a shaft 7 that connects the motor and the rotary drum, and a motor that supports the shaft. It consists of a fixed drum 2. Signals are sent and received to the rotating head from the fixed drum side via a non-contact signal transmission mechanism (not shown).

A notch 5 that opens toward the fixed drum is provided on the outer circumference of the rotating drum 1, and the rotary head 3 is inserted into the notch 5.
located within. In addition, at the outer periphery of the rotating drum 1,
A protrusion 4 is formed on a plane that is substantially the same as the plane of rotation of the rotary head 3. The protrusion 4 has a notch in the portion where the head 3 is installed.

When the protrusion 4 is enlarged, it is shown in Fig. 2. The rotating head 3 is fixed to a head base 8. In order to position the rotating head 3 with high precision, the head base 8 is fixed to the rotating drum with the same surface on which the rotating head is fixed as the rotating drum side. With such attachment, the surface of the rotary head f fixed to the head base 8 and the end surface of the rotary drum 1 on the fixed drum side are set to be on the same plane.

The protrusion 4 is an extension of the end surface of the rotating drum 1 on the fixed drum 2 side. The height h of the protrusion is h relative to the head height d.
<d. Further, the shape of the protrusion is such that the tip portion is narrow and smoothly slopes toward the base portion. The thickness of the tip of the protrusion is several times the thickness of the head 3.

The operation of the drum configured as described above will be explained below.

FIG. 3(a) shows the deformed state of the tape 9 near the protrusion 4. If there is no protrusion, the tape will wrap around the drum as shown at 9' in the figure, but if there is protrusion 4, the tape will be lifted up by the protrusion as shown in the figure. At this time, the amount of deformation of the tape is approximately equal to the height h of the protrusion 4.

FIG. 3(b) shows a state in which the tape is deformed on the rotary head 3. The tape 9, which would be deformed as shown in FIG. 3(a) without the head, becomes deformed as shown in FIG. 3(b) due to the rotating head. That is, the tape is deformed by the head, and the amount of deformation is approximately equal to the protrusion amount d of the head.

Next, a mechanism in which tape vibration is reduced by the protrusion 4 will be explained with reference to FIGS. 4(a) and 4(b).

FIG. 4(a) shows a conventional drum device IO.

The tape 9' is attached to the guide post 11 and the drum' when there is no head. It is placed at a position M that is in contact with 0. As the rotary head 3' rotates, the tape 9' is gradually lifted from the outer peripheral surface of the drum. Since the tip of the rotating head generally has a curvature in the rotation direction, the amount of tape movement is maximized when the center of the head approximately coincides with the point of contact between the tape and the drum.

The tape movement at this time roughly matches the head protrusion amount d.
Since the tape is stretched with a predetermined tension T, the tape position at this time, if defined in a static state without considering tape vibration, will be the N position in the figure. However, since the head is rotating at high speed, a periodic external force is applied to the tape 9' at the position where it contacts the drum, causing the tape to displace as shown in FIG. 5(c). Therefore, the tape in its free section generates string vibrations.

Here, (a) is a drum rotation signal, and (b) is a head passing signal.

FIG. 4(b) shows a drum 1 according to an embodiment of the present invention. The tape position on the same plane as the head 3 is as shown by M' and N' in the figure. M' is approximately at this position except when the tape is in contact with the protrusion 4, which is when the head passes through. When the head passes through, it is at position N' in the figure. This is the same position as N in the conventional drum if the head protrusion amount d is the same. At this time, a periodic external force is applied to the position where the tape 9 contacts the drum, causing the tape to be displaced as shown in FIG. 5(2). Here, when comparing Fig. 5 (c) and (2), in (2) the tape displacement d' is smaller by the height h of the protrusion 4, and the time during which the external force is applied is also shorter. .

Further, in the case of conventional drums, the tape cross section of the free section is flat, but according to the drum of the present invention, the tape cross section has a shape as shown in FIG. 3(a) due to the projections 4. , the tape stiffness is improved due to the shape effect.

As a result of the above-described effects, tape vibration in the free section is reduced compared to the conventional tape vibration, thereby reducing noise and image jitter, thereby making it possible to obtain a highly reliable magnetic recording and reproducing device.

In this embodiment, a case has been described in which the protrusions 4 are installed on the entire outer circumference of the rotating drum, but the same effect can be obtained even if the protrusions 4 are installed only in the vicinity of the head mounting portion. Also,
The shape of the protrusion is not limited to the trapezoidal cross-sectional shape shown in this embodiment, but may have any cross-sectional shape as long as it has a size that allows recording and reproduction by the head.

〔Effect of the invention〕

According to the present invention, it is possible to reduce tape vibration when the rotating head enters or leaves the tape, thereby reducing noise and image jitter, thereby providing a highly reliable magnetic recording and reproducing device. This has the effect of realizing the following.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the vicinity of the rotating head, FIG. 3(a) and FIG. 3(b) I
! I is an enlarged view of tape deformation, Figures 4(a) and 4(b)
) is an explanatory diagram of tape vibration, and FIG. 5 is a diagram showing the relationship between drum rotation and tape displacement. DESCRIPTION OF SYMBOLS 1... Rotating drum, 2... Fixed drum, 3... Rotating head, 4... Protrusion, 5... Notch, 6... Drive motor, 7... Shaft, 8... Head Base, 9...Magnetic base, 10 pieces 13 (O-冫O ya 3(b) sweet cow (a-)

Claims (3)

[Claims] 1. It includes a rotating head and a rotating drum, and a magnetic tape is run while being helically wound around the rotating drum, and signals are recorded or reproduced diagonally on the magnetic tape by the rotating head slightly protruding from the outer peripheral surface of the rotating drum. A magnetic recording/reproducing device characterized in that a protrusion with a height not exceeding the protrusion of the rotary head is provided on the outer periphery of the rotary drum on substantially the same plane as the rotation plane of the rotary head. Recording and playback device. 2. The magnetic recording and reproducing device according to claim 1, wherein the protrusion has a smooth cross-sectional shape with a narrow tip and a thicker base. Device. 3. 2. A magnetic recording and reproducing apparatus according to claim 1, wherein the width of the tip of the protrusion is approximately five times or less than the width of the rotary head.