JPS59165233A - Rotary head assembly - Google Patents

Abstract

PURPOSE:To adjust the height of a head within microtolerance only by a magnetic head position adjusting member such as a set screw by forming plural through-holes and slit linking them in a flank of a head base or applying a parallel spring mechanism. CONSTITUTION:An element 11 is an upper rotary cylinder, and 12 is a magnetic head; and 13 is the head base consisting of an elastic member, and 14 is the set screw as the member for adjusting the position of the magnetic head. The two through-holes 15 and slit 16 linking them are formed in the flank of the head base 13. When the head base 13 is pressed by the set screw 14, the circumference of the magnetic head fitting part of the head base 13 moves while holding itself in level within <=50mum displacement, so the magnetic head 12 is almost at right angles to the rotating shaft of the upper rotary cylinder 11 within an at least <=50mum adjustment amount of its height.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotary head assembly for a video tape recorder (hereinafter referred to as VTR).

Conventional Structure and Problems Generally, as shown in FIG. 1, a rotating head assembly of a VTR consists of an upper rotary cylinder 1 and a lower fixed cylinder 2, which have approximately the same outer diameter and are coaxially arranged. In the gap between the rotary cylinder 1 and the lower fixed cylinder 2, a magnetic head 3 whose tip protrudes outward from the cylindrical surface of the two cylinders and rotates coaxially with the two cylinders is constructed. Reference numeral 4 designates a magnetic tape that is helically wound around this rotary head assembly and runs at a constant speed. Reference numeral 5 designates a stepped portion that regulates the running position of the magnetic tape 4 in the width direction. The magnetic head 3 rotates at 1800 rpm and records and reproduces video signals on the magnetic tape 4.

In FIG. 1, arrow A indicates the running direction of the magnetic tape 4, and arrow B indicates the rotation direction of the upper rotating cylinder 2. FIG. 2 is a sectional view showing an example of the conventional structure of the rotary head assembly. In Figure 2, 7 is the rotation axis, 8
9 is a bearing, and 9 is a helad base. 2-part rotation/The cylinder 2 and the rotating shaft 7 are rotatably supported coaxially with the lower fixed cylinder 1 via a bearing 8, and are rotationally driven by a drive motor (not shown).

Now, in the above-mentioned rotating head assembly, the two magnetic tapes 3 arranged at 1800 degrees with respect to the rotating shaft alternately come into sliding contact with the magnetic tape 4, and the upper rotating cylinder 2 rotates once, the image signal of one frame of the television screen is recorded or played back. With the increase in the recording time on a tape of the same length and the miniaturization of VTRs, the recording density has become significantly higher, and the distance between adjacent tracks has become approximately 20 μm. Therefore,
The mounting of the magnetic head 3 requires extremely high positional accuracy, and in particular, the height of the reference rod 3 of the lower cylinder 10 must fall within a tolerance of 2 to 3 μm. However, it is impossible to keep the height of the assembled magnetic head 3 from the reference plane within a tolerance of 2 to 36 m by only increasing the processing accuracy of each component, and conventionally, as shown in FIG. The height of the magnetic head 3 was adjusted by pressing the vicinity of the head base 9 with the set screw 1o and bending the head base 9. However, with this adjustment method, as shown in FIG. 4, the head base 9 is deformed and the magnetic head 3 is tilted, making it impossible to maintain sufficient contact between the tip end surface of the magnetic head 3 and the magnetic tape 4. Magnetic head height 4-6/1m
The adjustment was limited.

Figure 6 shows that the head height can be adjusted from 4 to 4 with the set screw 1o.
The output signal waveform when the distance is 571 m or less (Fig. 5 (a)) and the output signal waveform when the distance exceeds 571 m (Fig. 5 (b)
) to show the difference.

Therefore, if the error in the head height after assembly exceeds 4 to 5 μm, a spacer (mm) of an appropriate thickness should be placed between the mounting surface of the head base 9 of the upper rotating cylinder 2 and the upper end surface of the head base 9. ) had to be interposed. In reality, the tolerance of the head height after assembly is limited to approximately ±20 ltm, and it is impossible to omit the process of selecting and clamping the spacer, leading to increased costs.

Purpose of the Invention In view of the above drawbacks, the present invention provides a head base that makes it possible to adjust the head height within a tolerance of ±2 to 311 m by simply pressing the head base with a set screw without requiring a spacer. The present invention provides a rotating head assembly that applies the following.

Structure of the Invention The present invention provides a lower fixed cylinder, a partially rotating ring having approximately the same diameter as the lower fixed cylinder and coaxially arranged with a gap, and a partially rotating ring mounted on the upper rotating cylinder. a magnetic head that is fixed to an end of the head base and rotates about the same axis as the lower fixed cylinder near the outer periphery of the lower fixed cylinder in the gap; and a magnetic head position adjustment member. The magnetic head position adjusting portion side of the head base is configured so that the front surface of the magnetic head of the head base is configured such that:
The upper rotating cylinder has a shape that moves up and down while maintaining a substantially right angle to the rotation axis of the upper rotating cylinder,
This has the advantage of making it possible to adjust the height of the magnetic head from the reference plane using only a magnetic head position adjustment member such as a set screw without requiring a spacer.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 6 is an enlarged sectional view of the vicinity of the head base of the rotary head assembly according to the embodiment of the present invention. In FIG. 6, 11 is an upper rotating cylinder, 12 is a magnetic head, and 13 is a magnetic head.
1 is a head base made of an elastic member, and 14 is a set screw as a member for adjusting the position of the magnetic head. As shown in FIG. 6, two through holes 16 and a slit 16 connecting the two through holes 16 are formed in the side surface of the head base 13.

The operation of the rotary head assembly configured as above will be described below.

FIG. 7 shows the head base 1 when the head base 13 is pressed by the set screw 14 in the embodiment of the present invention.
3. FIG. 3 is an explanatory diagram schematically showing the mechanism of deformation of the through hole 15. In Figure 7, 17.18 is a through hole, 19
20 is an elastic plate corresponding to a head base, and 21 is a fixed wall. The shape of the elastic plate 2Q before deformation is shown by a solid line, and the state of deformation when a force is applied to the position of arrow F is shown by a broken line. As shown in FIG. 7, the portion C of the elastic plate 20 always moves approximately in parallel within a predetermined deformation amount 8. As shown in FIG.

FIG. 8 shows the deformation of the head base 13 when the head base 13 is pushed down by the set screw 14 in the embodiment of the present invention shown in FIG. 6. As explained with reference to FIG. 7, the magnetic head mounting portion of the head base 1-3 moves while remaining approximately parallel within a displacement of at least 50 μm, so that the magnetic head 12 is The height is maintained approximately perpendicular to the axis of rotation of the upper rotor/cylinder 11 within an amount of adjustment of at least 60 μm.

Therefore, when the height of the magnetic head is adjusted within 5 olIm using the setscrew 14, the output signal waveform before the height adjustment is as shown in FIG. It becomes as shown in figure Φ), and does not change at all.

As described above, according to this embodiment, by forming a plurality of through holes and slits connecting them on the side surface of the head base, the head position adjusting member such as a set screw can be used without using a spacer. The height of the magnetic head can be adjusted without adversely affecting the output signal while the rotary head assembly remains assembled.

Note that the same purpose as in the above embodiment can also be achieved by using a head base having a parallel spring mechanism as shown in FIGS. 10(a) and 10(b).

In FIG. 10, 22 is a head base made of an elastic member, 23 is a rectangular through hole, 24 is a magnetic head, and 25 is a head base made of an elastic member.
26 is a head base made of a material with high rigidity, and 26 is a parallel plate spring.

In addition, in the embodiment of the present invention, the head base is mounted on the upper rotating cylinder; as shown in FIG. Needless to say, the present invention can also be applied to a system comprising a vertically fixed cylinder and a rotary member on which a head base is mounted and rotates within the gap. Also, in Figure 11, 2
7 is an upper fixed cylinder, 28 is a lower solid piece cylinder, 29
3 is a fixed shaft, 30 is a rotating member, and 31 is a helad base.

As described above, the present invention has an aspect of the head base! By forming multiple through-holes and slits connecting them, or by applying a parallel spring mechanism, the rotating head assembly can be assembled with only a magnetic head position adjusting member such as a set screw, and the width of several tens of microns can be reduced. It is possible to adjust the height of the magnetic head by a fairly large amount, and it saves the time and effort of selecting a spacer of an appropriate thickness and adjusting the height.
This has a significant practical effect as it eliminates the cost of spacer materials.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a rotary head assembly, FIG. 2 is a sectional view of a conventional rotary head assembly, FIG. 3 is an enlarged partial sectional view of the conventional rotary head assembly, and FIG. 4 is the rotary head assembly of FIG. 3. 5(a) and 5(b) are enlarged partial cross-sectional views of the magnetic head showing the deformation of the head base when the head base is pressed by the set screw, respectively. Diagram showing the output signal waveform, No. 6
The figure is a partially enlarged sectional view of a magnetic head of a rotary head assembly according to an embodiment of the present invention, FIG. 7 is an explanatory diagram schematically showing how the head base is deformed in an embodiment of the present invention, and FIG. In the rotating head assembly shown in FIG. 6, an enlarged partial cross-sectional view of the magnetic head showing how the head base is deformed when the hand base is pressed against the set screw. 6 and 8, FIG. 10(a), Φ) is a sectional view showing an example of the shape of the navel base in another embodiment of the present invention, and FIG. 11 is a diagram showing the shape of the upper and lower cylinders. FIG. 2 is a cross-sectional view of a fixed rotary head assembly. 11... Upper rotating cylinder, 12... Magnetic head, 13... Head base, 14... Set screw, 15... Through hole, 16... Slit . Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Fig. 4 Fig. 5 tb) Shingo Plate Dosa Gun Gahiji〉 Fig. 6/, 5 a57 Fig. 8 Fig. 9

Claims (4)

[Claims] (1) a lower fixed cylinder, an upper rotating cylinder having approximately the same diameter as the lower fixed cylinder and arranged coaxially with a gap therebetween, a head base mounted on the upper rotating cylinder, a magnetic head fixed to an end of the head base and rotating about the same axis as the lower fixed cylinder near the outer periphery of the lower fixed cylinder in the gap;
and a magnetic head position adjusting member, and the head base is configured such that the magnetic head mounting surface of the head base is substantially aligned with the rotation axis of the upper rotating cylinder by the magnetic head position adjusting member. A rotating head assembly with a shape that moves up and down while maintaining a right angle. (2) The rotating head assembly according to claim 1, wherein two or more through holes and slits connecting the through holes are formed in the side surface of the head base. (3) Having approximately the same diameter and the same throughout the gap: ll1b
a pair of fixed cylinders arranged in the same direction; a rotating member that rotates coaxially with the fixed cylinder in the gap;
A head base mounted on the rotating part side, a magnetic head fixed to an end of the head base and rotating around the same axis as the fixed cylinder near the outer periphery of the fixed cylinder in the gap, and magnetic head position adjustment. The head base is configured such that the magnetic head adjustment member allows the mounting of the magnetic head on the head base to be substantially perpendicular to the central axis on the rotating part side. A rotating head assembly with a shape that moves up and down. (4) The rotary head assembly according to claim 3, wherein the side surface of the navel base is formed with at least two through holes and slits that connect the through holes.