JPH01130315A - Rotary head assembly - Google Patents

Abstract

PURPOSE:To evade wear of a head due to a tape to secure the video output in tape entrance and exit sides by projecting a face pressure adjusting part by an extent equal to or smaller than the extent of projection of a magnetic head. CONSTITUTION:In a part of a rotating member 13 in the vicinity of a magnetic head 14, a face pressure adjusting part 16 which has a coating layer having a relatively small extent of specific wear on the surface is projected by an extent equal to or smaller than the extent of projection of the magnetic head 14. The coating layer of the face pressure adjusting part is brought into contact with the tape in the vicinity of the magnetic head in the initial stage of wear of the head to relax the excessive pressing force which acts on the heads as a face pressure by the tape. According as wear of the head is advanced to reduce said pressing force, the coating layer of the face pressure adjusting part is worn to cover the reduction of the pressing force acting upon the head. Thus, head touch satisfactory for extension of the life of the head is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a rotary head of a signal input/output device using a magnetic tape, such as a video tape recorder (hereinafter abbreviated as "VTR") or a digital audio tape (DAT). It's about assembly.

As a representative example of conventional technology, a VH8 type VTR will be explained. As shown in FIG. 2, a conventional rotary head assembly has 18 magnetic tapes (hereinafter referred to as "tape") for 1 magnetic tape (hereinafter abbreviated as "tape").
A rotating member 2 that rotates and slides at a speed of 0.00 zpm and a fixed cylinder 3 that slides without rotating are disposed above and below and are configured to hold them. The lower fixed cylinder 3 is provided with a lead 4 for regulating the position of the tape 1 in the width direction during running. A magnetic head (hereinafter abbreviated as "head") 6 is provided at the lower end of the outer circumference of the upper rotating member 2. This head 6 performs a helical scan on the tape 1 with precision. This is for recording and reproducing video signals. Reference numeral 6 designates a head mounting window provided on the rotating member 2.

The head 5 is held so as to protrude outward from the outer peripheral surface of the rotating member 2 by approximately several tens of microns. (in Figure 2) and (C
) are schematic diagrams respectively showing a cross section and a longitudinal section of a conventional rotary head assembly.

Problems to be Solved by the Invention However, when recording and reproducing video signals, the head on the rotating member rotates at high speed and slides in contact with the tape, so there is a gap between the head surface and the contact surface of the tape. A wear phenomenon occurs, and the head wears out depending on the usage time. On the other hand, wear also occurs between the rotating member itself and the tape.
The abrasion powder generated due to the above reasons adheres to the tape or the head/rotating member and moves, causing new abrasion and accelerating the abrasion of the rotary head assembly and the tape.

In this case, if abrasion powder adheres to the most protruding head of the rotary head assembly, it becomes impossible to input and output video signals, and the original functions of the VTR cannot be performed at all. Also, one of the functions of a VTR is still playback. This refers to a function that plays back still images by rotating a head on a rotating member without running the tape, which increases damage to specific parts of the tape and
Head wear is also promoted. If this still playback is performed with abrasion powder adhering to the rotating member including the head as described above, the magnetic layer of the tape will fall off from the resin base material, making the tape partially unusable.

As a result of a detailed experimental study of the wear phenomenon between the rotating head assembly and the tape, we found that fatal wear with the tape is influenced by the magnitude of the tape reaction force in the radial direction of the rotating member near the head mounting window. It became clear that as the reaction force increased in the direction, significant head wear occurred.

From a completely different point of view, at the beginning of tape winding on the rotating head assembly (referred to as the ``tape input side'') and the nine end portion of tape winding (referred to as the ``tape output side''), the head is positioned at the lower end in the tape width direction. Since scanning starts and ends by fanning the tape from the top or top of the tape, the contact with the tape may be incomplete, making it difficult to output the tape.This phenomenon is commonly used as a method for verifying video output signals. This can also be confirmed by monitoring the envelope signal generated. Figure 3 (-) shows the envelope output when the ideal head touch is achieved, and Figure 3 (B) shows the tape input and output fill.
This is the basic pattern of envelope output that occurs when the output signal is not sufficiently extracted.

The current rotary head assemblies of VTRs have the problem of head wear and the problem of ensuring output on the tape input and output sides.

In view of the above-mentioned problems of the prior art, the present invention avoids tape head wear and at the same time secures video output at the tape input and output sides, thereby achieving high reliability and durability and improving video signal input/output characteristics. This provides an excellent rotating head assembly.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides that a fixed member and a rotating member, which are substantially cylindrical and have substantially the same diameter, are coaxially arranged one above the other, and a magnetic head is attached to the rotating member. In addition, in a rotary head assembly that protrudes from the circumference, a surface pressure adjustment part having a coating layer with a relatively small amount of specific wear as shown in Table ml is installed near the magnetic head of the rotating member according to the amount of protrusion of the magnetic head. The magnetic head is characterized in that the magnetic head protrudes approximately the same amount or has a protrusion amount equal to or less than the protrusion amount of the magnetic head.

According to the above-mentioned structure, the coating layer of the surface pressure adjusting section comes into contact with the tape in the vicinity of the magnetic head in the early stage of head wear, so that surface pressure is applied from the tape to the head. Excessive pressing can relieve the force. Also,
As the wear of the head progresses and the pressing force acting from the tape on the head in the form of surface pressure decreases, the coating layer of the surface pressure adjustment part wears away and the amount of specific wear decreases compared to the coating layer. Since the pressing force can be received by the surface pressure adjustment part itself, which is large and easily worn out, the pressing force acting on the head can compensate for the decrease in force.

As a result, in the initial state of head wear, head wear is suppressed and the life of the head is greatly extended, and as head wear progresses, the pressure applied to the head maintains its force, especially on the tape entry side. It is possible to improve the head contact condition at the tape end portion such as the exit side portion, create a good surface head-tape contact condition, and improve the envelope output.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings. In FIG. 1(,), 11 is a tape, 12 is a substantially cylindrical rotating member disposed above, and 13 is a rotating member 1.
2, a fixing member coaxially arranged with approximately the same diameter as 2; 14, a head protruding from the outer circumferential surface at the lower end of the rotating member 12; 16, a helical-shaped fixing member provided on the outer circumferential surface of the fixing member 13; A lead 16 is a surface pressure adjustment member provided on the rotating member 12 close to the top and bottom of the head 14 in the rotational direction ω.

The outer peripheral tip of the surface pressure adjusting member 16 that comes into contact with the tape 11 is provided with a coating made of a substance with a relatively small specific wear amount (hard to wear). The surface pressure adjustment member 16 itself is
It is made of a base material with a high specific wear rate, such as glass.

The specific structure of the surface pressure adjusting member 16 of this embodiment will be explained while comparing it with the conventional example shown in FIG.

The upper and lower wall thicknesses of the heads 14 and 6 are h01 rotating member 12
If the amount of protrusion from the outer peripheral surface is δ, then normally h〇 near 0~
It is often set to 300/jm and δ25 to 5011 m. Here, the surface pressure adjusting member 16 is desirably set within 5 degrees i/(with respect to the head 14 in the thickness direction and rotational direction ω).

According to this embodiment, the surface pressure adjusting member 16 plays the role of supporting the tape 11, the tape 11 comes into smooth contact with the head 14, and the surface pressure of the tape against the head 14 is significantly reduced. On the other hand, in the conventional example, as shown in FIG. 2(c), since the tape 1 is rapidly stretched at the head 6, the tape surface pressure acting on the head becomes high.

Attach a strain gauge to the heads 14, 5, and tape 11,
By actually measuring and comparing the head surface pressure from No. 1, it was confirmed that by providing the surface pressure adjustment member 16, the surface pressure could be reduced to about % or less of the conventional value.

Setting the surface pressure adjusting member 16 so that its protrusion amount is approximately 60 inches to 10% of the head protrusion amount 6 is most effective in reducing the head surface pressure. Further, the contact portion of the surface pressure adjusting member 16 with the tape 11 is preferably provided with a radius of curvature of 2 (HIS or less) in the vertical and horizontal directions, similarly to the head.

According to this embodiment, in the initial state of wear of the head 14, the head surface pressure from the tape 11 can be reduced and suppressed by setting the surface pressure adjusting member 16 as described above. However, as the wear of the head 14 progresses and the amount of protrusion δ of the head 140 from the outer peripheral surface of the rotating member 12 decreases, the head surface pressure from the tape 11 decreases excessively. It is necessary to reduce the reduction effect and ensure an appropriate force for pressing the head of the tape 11.

On the other hand, since the surface pressure adjusting member 16 is provided with a solid lubricant coating having a small specific wear amount on its outer peripheral tip, the head 1
As the wear progresses, the coating is worn away, and the head pressing of the tape 11 receives part of the force from the base material of the surface pressure adjustment member 16 itself, which has a large specific wear amount. 1
It becomes possible to significantly weaken the head surface pressure reduction effect of No.6. As a result, after the head wears down, the tape can be pressed against the head without weakening the force.

The thickness of the coating of the surface pressure adjustment member 16 should be set to about 6% to 0.000cm of the amount of protrusion of the surface pressure adjustment member 16 from the rotating member 12, in order to secure the force when pressing the head of the tape 11. good.

FIG. 4 shows the head life test results for this embodiment and the conventional example. It is clear that the life of the head was significantly extended by setting the surface pressure adjustment member.

Effects of the Invention According to the present invention, excessive head surface pressure that promotes head wear is alleviated and suppressed, and after head wear progresses, an appropriate head surface pressure is ensured, thereby extending head life and achieving good head touch. be able to.

[Brief explanation of the drawing]

FIG. 1(, ) is a perspective view of a rotary head assembly according to an embodiment of the present invention, FIGS. ) is a perspective view of a conventional rotary head assembly, and (b) and (c) are diagrams showing test results of head life in an embodiment of the present invention and a conventional example, respectively. 11... Tape, 12... Rotating member, 1
3...Fixing member, 14...Head, 1
6... Surface pressure adjustment member. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Fig.4

Claims (4)

[Claims] (1) In a rotating head assembly in which a fixed member and a rotating member that are substantially cylindrical and have substantially the same diameter are coaxially arranged one above the other, and a magnetic head is provided protruding from the outer periphery of the rotating member, the magnetic head of the rotating member A surface pressure adjustment part having a coating layer with a relatively small amount of specific wear on the surface is provided in the vicinity of the magnetic head by a protruding amount that is approximately the same as the protruding amount of the magnetic head or less than the protruding amount of the magnetic head. Rotating head assembly. (2) The rotary head assembly according to claim 1, wherein the surface pressure adjusting portions are arranged before and after the magnetic head in the rotational direction. (3) The rotary head assembly according to claim 1, wherein the surface pressure adjusting portions are arranged above and below in the rotational direction of the magnetic head. (4) The rotary head assembly according to claim 1, wherein the surface pressure adjusting portions are disposed at the front and rear and at the top and bottom in the rotational direction of the magnetic head.