JPH03224157A - Drum for magnetic recording and reproducing - Google Patents

Abstract

PURPOSE:To simultaneously decrease tape oscillations with one member on both sides of a part where winding on a drum starts and where the winding ends by projecting members for projection on both sides of the part where the winding of a magnetic tape on the drum starts and the part where the winding ends and allowing the fine adjustment of the rate of projection. CONSTITUTION:The members 4 for projection are projected to the outer peripheral surface of a stationary drum 3. These members 4 for projection are so positioned as to project near 6A the part where the winding of the magnetic tape 6 on the drum starts and near 6B the part where the winding ends and not to project in the central part of winding. The rate of projection is finely adjusted by moving the members 4 for projection in this case. Namely, the members 4 for projection are fastened to the stationary drum 3 by means of screws 5 and springs 7 are inserted between the members 4 for projection and the stationary drum 3, by which the fine adjustment is easily executed. The tape oscillation is decreased in this way and the formation of the projecting parts of the part 6A where the winding of the tape starts and the part 6B where the winding ends with one member 4 is possible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording and reproducing device, and a method for reducing the vibration of a magnetic tape when a rotating head enters and exits a part of the drum where the magnetic tape is wound. The present invention relates to a magnetic recording and reproducing drum suitable for.

[Prior Art] A magnetic recording/reproducing device such as a video tape recorder generally has a rotating head (1) as shown in FIG. 9, and scans the magnetic tape and the rotating head (1) relative to each other. Recording and playback is performed by In order to maintain a constant state of contact between the rotating head (1) and the magnetic tape, a fixed drum (3) is disposed coaxially with the rotation axis of the rotating drum (2) that has the rotating head (1) and rotates. The structure is such that the tape is wrapped around the drum. And the rotating head (1)
protrudes slightly from the outer peripheral surface of the drum.

The magnetic tape is wound around the drum while being guided by the guide post. For this reason, the magnetic tape is kept running only by being stretched with a predetermined tension between the drum and the guide post. The stationary drum (3) has guide shoulders (3A) for the widthwise positioning of the magnetic tape relative to the drum.

Since the rotary head (1) slightly protrudes from the outer circumferential surface of the drum, when the rotary head (1) enters the magnetic tape, it has the effect of lifting the tape by the amount of this protrusion. After the rotating head has passed, the magnetic tape comes into contact with the drum surface again. In this way, deformations will be imparted to the magnetic tape during the passage of the rotating head (1). When the rotary head (1) separates from the magnetic tape, the deformation of the magnetic tape is recovered. Such deformation and recovery causes the magnetic tape to vibrate, resulting in tape vibration. This tape vibration generates noise and causes velocity fluctuations in the running direction of the magnetic tape, causing distortion of the image called jitter on the screen.

As a method for reducing this tape vibration, JP-A-62-
In No. 132257, a fixed drum (3') having a shape as shown in FIG. 8 is devised. FIG. 8(a) is a side view of this fixed drum (3'), and FIG. 8(b) is a partial view thereof, showing that the protrusion (25) is provided on the fixed drum (3'). There is. In addition, the protrusion (25) is attached to the fixed drum (3).
As methods for providing the protrusion (25), it has been proposed to 1) leave the protrusion (25) uncut during cutting of the stationary drum (3'), and 2) create the protrusion (25) by attaching another member.

[Problems to be Solved by the Invention] In the above-mentioned Japanese Patent Application Laid-open No. 132257/1983, it is possible to reduce tape vibration when the rotary head is detached, but the following problems arise.

1) It is not possible to reduce tape vibration when the rotating head enters. 2) It is not possible to finely adjust the amount of protrusion of the protrusion. 3) In order to solve the problem in 1), a protrusion is also provided at the beginning of the winding process. In this case, it is difficult to provide uncut and protruding windings on both sides of the start and end portions during cutting. Furthermore, it is difficult to attach separate members to both sides to create a protrusion and finely adjust the amount of protrusion.

This invention was made in order to solve the above-mentioned problems, and it is possible to reduce the tape vibration when the rotating head enters and leaves the rotating head, and the tape winding is performed on the protrusions at the start and end parts. It is an object of the present invention to provide a magnetic recording/reproducing device which can realize the following with a single member and facilitate fine adjustment.

[Means for Solving the Problem] Reduction of tape vibration is achieved by reducing the force for deforming the tape in an out-of-plane direction when the head enters or exits 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 peripheral surface of the drum. However, simply reducing the amount of protrusion will make the contact between the head and tape unstable, resulting in poor recording. This causes the inconvenience that playback cannot be performed.

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 occurs because the tape deformation force periodically fluctuates, so in order to reduce this periodic fluctuation force, a constant deformation force is applied to the tape at all times.
Reduces the variation in deformation force when the head enters or leaves the head.

[Operation 1] In order to reduce fluctuations in tape deformation force, a protruding member is attached to the outer peripheral surface of the fixed drum so as to protrude in the radial direction of the fixed drum. The tape is always in contact with the protrusion member. As a result, when the rotating 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.

In addition, when the magnetic tape is wound on a drum, the protrusion member protrudes on both sides of the start and end parts of the section, and the amount of protrusion can be finely adjusted. A large amount of overhang can be achieved.

[Example 1 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the shape of the drum of the present invention.

This drum consists of a rotating head (1) for performing magnetic recording and reproduction, a rotating drum (2) that rotates together with the rotating head (1), a fixed drum (3), and a protruding member (4).

FIG. 2 is a perspective view of the protruding member (4), and FIG. 3 is a perspective view of the stationary drum (3). However, in this figure, things unnecessary for explanation are omitted.

FIG. 4 is an enlarged view of the position adjustment portion of the protruding member (4). The protrusion member (4) is attached to the fixed drum (3) with a screw (5).
), and the protruding member (4) and fixed drum (
By inserting the spring (7) between 3), the arrow (
9) Fine adjustment of the direction is easily performed. At this time, the protrusion member (4) moves along the guide groove (3C) of the fixed drum (3).

FIG. 5 is a diagram showing the positional relationship between the fixed drum (3) and the protruding member (4). The shaded portion is a portion where the protrusion member (4) protrudes from the outer peripheral surface of the fixed drum (3). As shown in the figure, when winding the magnetic tape (6) on the drum, the protruding member (4) protrudes near the start part (6A) and near the end part (6B), and the winding is positioned so that it does not protrude in the center. do. However, the arrow (10) is the direction in which the tape travels during normal playback. The amount of protrusion is finely adjusted by moving the protrusion member (4) in the direction of the arrow (9). Further, since the adjustment screw is located at the position shown in FIG. 1, the apparatus of the present invention allows adjustment to be made during recording and reproduction.

Next, a mechanism for reducing tape vibration due to the protrusion of the protruding member (4) will be explained with reference to Fig. 6. Fig. 6(a) shows a conventional drum device. The magnetic tape (6') is arranged at a position (M') where it would be in contact with the guide post (8') and the rotating drum (2') when there is no rotating head (1').

As the rotating head (1') rotates, the magnetic tape (6')
is gradually lifted from the outer circumferential surface of the drum. Since the magnetic tape (6') is under a predetermined tension (T), if it is defined in a static state without considering dynamic effects, it will be at the position (N') when it is moved to the maximum. However, since the head is rotating at high speed, dynamically the tape generates string vibrations in its free section. The measurement results of this string vibration are as shown in FIG. 7(b). (A) in FIG. 7 shows the timing of head entry.

FIG. 6(b) shows an embodiment of the present invention. Similarly, considering statically, the magnetic tape (6) moves in the range from (M) to (N). In this case, the amount of movement is reduced by the amount of protrusion of the protruding member (4).

Also, from a dynamic point of view, tape vibration is reduced.

The measurement results of this string vibration are as shown in FIG. 7(C).

[Effects of the Invention] According to the present invention, the formation of protrusions for reducing tape vibration when the rotating head enters or leaves the tape is performed by forming one protrusion on both sides of the drum winding start and end. This has the effect of realizing a magnetic recording/reproducing device that can be simultaneously realized using members and that allows fine adjustment to be easily made.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a magnetic recording/reproducing drum according to an embodiment of the present invention, FIG. 2 is a perspective view of a protrusion member used in the embodiment of FIG. 1, and FIG. A perspective view of the fixed drum used in the example, FIG. 4 is an enlarged view of the position adjustment part of the ejecting member, FIG. 5 is an explanatory diagram of the positional relationship between the fixed drum and the ejecting member, and FIG. 6 is a conventional FIG. 7 is a diagram for comparing the magnitude of change in the amount of deformation of the magnetic tape in the case of the magnetic recording and reproducing drum of the present invention and the magnitude of change in the amount of deformation of the magnetic tape in the case of the magnetic recording and reproducing drum of the present invention. is a diagram comparing the magnitude of vibration of the magnetic tape between the conventional example and the case of the present invention,
FIG. 8 is a diagram showing the structure of a fixed drum for reducing the vibration of a magnetic tape according to the prior art, and FIG. 9 is a conventional magnetic recording and reproducing drum that precedes the magnetic recording and reproducing drum shown in FIG. FIG. In the figure, (1) is a rotating head, (2) is a rotating drum, (3) is a fixed drum, (4) is a protrusion member, (5) is an adjustment screw, (6) is a magnetic tape (7) is spring,
(8) is a guide post, and (9) is an arrow indicating the moving direction of the protrusion member. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) Consisting of a rotating head, a rotating drum, and a fixed drum, the rotating head runs while winding a magnetic tape helically around the rotating drum and the fixed drum, and protrudes slightly from the outer peripheral surfaces of the rotating drum and the fixed drum. In a magnetic recording and reproducing drum for recording and reproducing signals obliquely on the magnetic tape, a member having a portion with a radius of curvature approximately equal to the radius of the fixed drum on the end surface of the fixed drum on the rotating drum side. so that the member protrudes in the radial direction of the fixed drum with respect to the fixed drum near both ends of the drum-wrapped portion of the magnetic tape, and does not protrude anywhere other than near both ends of the drum-wound portion of the magnetic tape. 1. A magnetic recording and reproducing drum, which is attached to a drum and is characterized in that the amount of protrusion of the member can be finely adjusted.