JPS62264415A - Rotary head assembly for magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent a head mounting part from being dislocated, by forming a rotary cylinder by a plastic, forming the head mounting part by an insert member of rotation symmetry made of a metal, and positioning the head mounting part within a die. CONSTITUTION:A positioning in a diameter direction is performed by fitting the cavity outer periphery 13A of a die 13 in the outer periphery 28 of the head mounting part, and the positioning in a circumference is performed by fitting a head window 16 in the die 13, and fitting a positioning pin 14 in a head mounting screw hole 15. Also, since the positioning pin 14 is fitted in the mounting screw hole 15, it is prevented to fill a screw thread by the inflow of the plastic to the head mounting screw hole 15. Thus, since the positioning of a head mounting part 3 is performed accurately within the cavity of the die 13, no irregularity in rotation generated by the imbalance in the weight of a rotary cylinder 4, is generated, and all of the defective recording and reproduction due to the dislocation of a recording and reproducing head can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to improvements in a rotary head assembly for a magnetic recording/reproducing device such as a video tape recorder, and in particular to an improvement in its rotary cylinder.

[Conventional technology]

FIG. 8 is a sectional view showing a rotary head assembly of a conventional magnetic recording/reproducing apparatus disclosed in, for example, Japanese Utility Model Application Publication No. 60-31748. This is a recording and reproducing head for recording and reproducing information on a magnetic recording medium (magnetic tape) 8, and is attached to a head attachment part 3 using a head attachment screw 2, and the head attachment part 3 is a rotating head made of plastic. cylinder 4
It is integrally molded with. The head mount @3 is made of aluminum alloy in order to prevent the tightening strength of the head mount ↑ 2 from weakening. This is because if the recording/reproducing head 1 is directly attached to the rotary cylinder 4 made of plastic using the head attachment screw 2, the tightening strength of the head attachment screw 2 may be weakened due to shrinkage of the plastic. The rotating cylinder 4 is made of plastic containing 13% by volume and 7% by volume of particulate ferrite and carbon, respectively, so that the specific gravity is approximately equal to that of the aluminum alloy, and the position of the head mounting portion 3 is slightly shifted. Also, rotational unevenness is prevented from occurring when the rotating cylinder 4 rotates. A fixed cylinder 5 is equipped with a bearing mechanism 6 for supporting the rotary cylinder 4, and has a lead groove 7 on its outer circumferential surface for guiding the tape-shaped recording medium 8. 9
is a rotating shaft, 10 is a flange fixed to the rotating shaft 9, and the rotating cylinder 4 is fixed to the flange 10 by suitable means such as screws 11.

Next, the operation will be explained. When the rotating shaft 9 is rotated by an electric motor, the rotating cylinder 4 is rotated via a flange lO fixed to the rotating shaft 9. The recording/reproducing head 1 is attached to the rotary cylinder 4 via the head attachment part 3.
A recording signal is recorded on a tape-shaped recording medium 8 that moves along a lead groove 7 formed in a fixed cylinder 5, or an already recorded recording (No. 3) is reproduced.

[Problem that the invention seeks to solve]

The rotary head assembly of a conventional magnetic recording/reproducing device is constructed as described above.
The rotating cylinder 4 must be made of plastic containing 13% by volume and 7% by volume of carbon, respectively, and having approximately the same specific gravity as the head mounting portion 3 made of aluminum alloy.
Also, if the position of the head mounting part 3 shifts significantly, the weight balance of the rotary cylinder 4 will be disrupted, causing uneven rotation when the rotating cylinder 4 rotates, and if the position of the head mounting part 3 shifts, the position of the recording/reproducing head 1 will also shift, so this is a good thing. There were problems such as the inability to perform accurate recording and playback.

This invention was made to solve the above-mentioned problems.By accurately positioning the head mounting part within the mold cavity, the weight of the rotating cylinder due to misalignment of the head mounting part can be reduced. It is an object of the present invention to provide a rotary head assembly for a magnetic recording/reproducing device capable of eliminating rotational unevenness caused by imbalance and also eliminating recording/reproducing defects caused by positional deviation of the recording/reproducing head.

[Means for solving problems]

A rotary head assembly for a magnetic recording/reproducing apparatus according to the present invention is equipped with a rotary cylinder in which a head mounting portion is accurately positioned within a mold cavity.

[Effect]

In the rotating cylinder of the present invention, by accurately positioning the head mounting part within the mold cavity, uneven rotation caused by the weight imbalance of the rotating cylinder due to misalignment of the head mounting part is eliminated.
Recording/reproducing defects caused by misalignment of the recording/reproducing head are also eliminated.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 7.

In the figure, reference numeral 3 denotes a head mounting section corresponding to 3 of the conventional one, and as shown in FIGS. 1 and 2, the recording/reproducing head 1 is supported by the bottom fitting of the head mounting section. Since the head mounting portion 3 is made of metal such as aluminum, the tightening strength of the head mounting screw 2 does not weaken. Further, since the head mounting portion 3 is positioned in the diametrical direction by the cavity outer circumference 13A of the mold 13, the rotary cylinder outer diameter Di and the head mounting portion outer diameter d1 are the same.

FIG. 3 is a view of the head attachment part 3 seen from the fixed cylinder 5 side, and a tapered hole 12 is opened in the hole 12 to prevent the head attachment part 3 from falling off from the rotating cylinder. The hardened plastic after flowing into the head mounting part 3
Prevent missing items.

As shown in FIG. 4, positioning in the diametrical direction is achieved by fitting the cavity outer periphery 13A of the mold 13 and the head attachment portion outer periphery 3B, and the head window 16 is fitted with the mold 13, and the positioning pin 14 By fitting into the head mounting screw hole 15, positioning in the circumferential direction is performed. Furthermore, since the positioning pin 14 is fitted into the mounting screw hole 15, plastic is prevented from flowing into the head mounting screw hole 15 and filling the threads.

FIG. 5 shows another embodiment of the present invention, in which the positioning of the head mounting portion 3 in the diametrical direction is performed on the inner circumference 13B of the cavity of the mold 13, and the inner diameter D2 of the rotating cylinder and the inner diameter d2 of the head mounting portion are are the same.

FIG. 6 is a view of the head mounting portion 3 viewed from the side of the fixed cylinder 5, in which a hole 12 is provided to prevent the rad attachment portion 3 from falling off from the rotating cylinder.

As shown in FIG. 7, the cavity inner periphery 13B of the mold 13 and the head mounting portion inner periphery 3C fit together, thereby positioning in the diametrical direction.

Since the head mounting portion 3 is accurately positioned within the cavity of the mold 13 as shown in FIGS. 4 and 7, uneven rotation caused by imbalance of the weight of the rotary cylinder 4 does not occur at all, and recording Recording and reproducing defects due to positional deviation of the reproducing head 1 are completely eliminated.

In the conventional rotating cylinder 4, it is difficult to accurately position the head mounting part 3 within the cavity of the mold 13, and in order to prevent uneven rotation of the rotating cylinder 4 caused by slight positional deviation of the head mounting part 3. A rotating cylinder 4 is made of plastic having a specific gravity roughly equal to that of an aluminum alloy.
was forming.

However, when choosing a plastic to form the rotating cylinder 4, it is important to choose one that shrinks little when cooled to ensure shape accuracy, one that has excellent abrasion resistance against tape, and one that is soaked in conductivity to prevent static build-up. , we must consider various conditions such as materials that can be replaced with metals and have strength. However, since the conventional rotary cylinder 4 needs to have a specific gravity roughly equal to that of an aluminum alloy, it has not been possible to use plastic that is optimal for ensuring shape accuracy.

However, in the present invention, the specific gravity of the plastic is no longer a selection condition, so it becomes possible to form the rotating cylinder 4 using a plastic that satisfies various selection conditions such as ensuring shape accuracy.

〔Effect of the invention〕

As described above, according to the present invention, since the head mounting part is accurately positioned within the mold cavity, it is possible to eliminate uneven rotation caused by the weight imbalance of the rotating cylinder caused by the positional deviation of the head mounting part. This has the effect of providing a rotary head assembly for a magnetic recording and reproducing device in which recording and reproducing defects caused by misalignment of the recording and reproducing head are eliminated.

Furthermore, according to the present invention, the specific gravity of the plastic is no longer a criterion for selecting the plastic for forming the rotary cylinder, so there is an effect that the rotary cylinder can be molded using a plastic that satisfies various selection conditions such as ensuring shape accuracy.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a rotary head assembly of a magnetic recording/reproducing apparatus of the present invention, FIG. 2 is a longitudinal sectional view showing a rotating cylinder in the embodiment of FIG. 1, and FIG. 3 is an embodiment of the embodiment of FIG. FIG. 4 is a longitudinal cross-sectional view showing the state of the rotary cylinder during molding in the embodiment of FIG. 1, and FIG. 5 is another embodiment of the present invention. 6 is a plan view of the head mounting portion in the embodiment shown in FIG. 5, viewed from the fixed cylinder side. FIG. 7 is a longitudinal sectional view showing the rotating cylinder in the embodiment shown in FIG. Reproducing head, 3 is a head mounting part, 4 is a rotating cylinder, 5 is a fixed cylinder, 6 is a bearing mechanism, 7 is a lead groove, 8 is a tape-like marking;! medium, 9 is the rotating shaft, 12 is the hole,
13 is a mold, and 14 is a positioning pin. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa 1 k pull/false t 71 J: \nshi attack 1 ↑ screw 4: li, 4 & shift degree. Figure 2 Figure 3 Figure 5 Figure 6 Figure 7 Figure 8

Claims (3)

[Claims] (1) Rotation of a magnetic recording/reproducing device comprising a fixed cylinder having a lead groove for guiding a tape recording medium, and a rotating cylinder to which a recording/reproducing head is attached and rotatably supported by the fixed cylinder via a bearing mechanism. In the head assembly, the rotating cylinder is made of plastic, the head mounting portion is formed of a rotationally symmetrical metal insert member, and the head mounting portion is positioned within a mold. Rotating head assembly of the device. (2) The rotary head of the magnetic recording and reproducing apparatus according to claim 1, wherein the diametrical positioning of the head mounting portion is performed using the outer periphery or inner periphery within the cavity of the mold. ·assembly. (3) The scope of claims characterized in that the positioning of the head mounting portion in the circumferential direction is performed by fitting a hole provided in the head mounting portion into a pin provided in a cavity of the mold. A rotary head assembly for a magnetic recording/reproducing device according to item 1 or 2.