JPH0514329Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a rotary head assembly of a magnetic recording/reproducing device such as a video tape recorder, and in particular to improvements in the thrust fluid bearing thereof.

[Conventional technology]

Rotating head assemblies using thrust fluid bearings in conventional video tape recorders are
It has a structure as shown in FIG. In FIG. 7, reference numeral 1 denotes a magnetic head for recording and reproducing information on a magnetic tape, which is attached to a rotating cylinder 2. The rotating cylinder 2 is fixed to the radial flange 3 by screws. 4 is a fixed cylinder, and a lead groove 401 for guiding the running of the tape is formed on its outer peripheral surface. A fixed shaft 5 is fixed to the fixed cylinder 4 at one end thereof. Spiral grooves 6 and 7 are formed on the outer periphery of the upper and lower parts of the fixed shaft 5, and between the fixed shaft 5 and the radial flange 3,
8 constitutes a radial fluid bearing. Although not visible in FIG. 7, a spiral groove is formed on the other end surface of the fixed shaft 5, and a thrust fluid bearing is formed between it and the thrust flange 9 via a bearing medium (for example, grease) 10. There is. This thrust flange 9 is fixed to the radial flange 3 with screws. A rotating side rotary transformer 11 of a cylindrical rotary transformer that transmits, receives, and amplifies signals from the magnetic head 1 is fixed to the radial flange 3 by a method such as adhesion. Further, a fixed side rotary transformer 12, which is paired with this, is fixed to the fixed cylinder 4 by a method such as gluing. Reference numeral 13 denotes a stator of a drive motor for the rotary cylinder 2, which is fixed to the fixed cylinder 4 by adhesives, screws, or the like. 14
is the rotor magnet of the drive motor, which is glued to the rotor case 15 and attached to the rotor case 1.
5 is fixed to the radial flange 3 by adhesive or screwing.

Rotating head assemblies using such hydrodynamic bearings have recently become more popular because they are advantageous in terms of vibration, noise, and rotation accuracy compared to rotating head assemblies using ball bearings.

[Problem that the invention attempts to solve]

However, the conventional rotary head assembly using a hydrodynamic bearing as shown in FIG. 7 has the following problems. That is, in a video tape recorder, for example, it is necessary to minimize the vertical fluctuation of the rotation locus of the magnetic head 1 relative to the magnetic tape. For this purpose, it is essential to maintain the mechanical accuracy of the rotating cylinder, and it is also necessary to maintain a certain level of accuracy for the bearing part. In particular, regarding the thrust fluid bearing, it is necessary to fix the bearing surface, that is, the thrust flange 9. It is necessary to keep the mutual parallelism between the surface facing the shaft 5 and the end surface 501 of the fixed shaft 5 and the coaxiality between the center of the spiral groove and the rotation center of the thrust flange 9 within a certain precision, and in order to achieve this, The problem was that the accuracy of parts had to be strictly controlled, which increased the cost of individual parts.

This invention was made to solve the above-mentioned problems, and its purpose is to provide a rotating head assembly that can realize a high-precision thrust fluid bearing at low cost.

[Means for solving problems]

The rotary head assembly according to this invention has a conical recess formed at the end facing the thrust flange of the fixed shaft, and a flat surface facing the thrust flange is housed in the recess and comes into contact with the recess. A bearing member having a spherical surface portion is provided, and a thrust fluid bearing is constructed with a bearing medium interposed between a flat surface of the bearing member and a thrust flange opposing the flat surface of the bearing member.

[Effect]

In this invention, since the spherical part of the bearing member is in contact with the conical recess of the fixed shaft, the surface of the thrust flange facing the fixed shaft and the flat surface of the bearing member are tilted to each other before assembly. Even if it is located
Furthermore, even if the central axis of the spiral groove formed on the surface facing the fixed axis of the thrust flange or the flat surface of the bearing member is misaligned with the central axis of rotation of the thrust flange (the central axis of rotation of the rotating cylinder),
After assembly, when the rotating cylinder rotates, the bearing member forms a stable positional relationship through the bearing medium between its flat surface and the opposing thrust flange surface due to the self-aligning action of the spherical part of the bearing member. However, the rotating cylinder now rotates with high precision and stability.

[Example of idea]

An embodiment of this invention will be described below with reference to FIGS. 1 to 3. Fig. 1 is a longitudinal cross-sectional view of this embodiment, Fig. 2 is an enlarged view of the main part of Fig. 1, Fig. 3 is a plan view of a bearing member forming the main part of this invention, and Fig. Parts that are the same as those in the above are given the same reference numerals and their explanations will be omitted. In the figure, 5A is a fixed shaft corresponding to 5 in FIG. . Reference numeral 16 denotes a bearing member, which includes a flat surface 161 facing the thrust flange 9 and the recess 50.
2 and in contact with this recess.
and has. 163 is the flat surface 16 of the bearing member 16
The spiral groove 164 formed in 1 is the central axis of the spiral groove 163, and a thrust fluid bearing is installed between the flat surface 161 of the bearing member 16 and the surface of the thrust flange 9 facing thereto via the bearing medium 10. is forming. Note that if the maximum diameter of the bearing member 16 (in this embodiment, the diameter of the flat surface 161) is made approximately equal to the diameter of the fixed shaft 5A, the housing shaft of the fixed shaft 5A can be used at that portion to accommodate the bearing member 16. This is preferable since there is no need to enlarge the hole. Further, the spiral groove may be formed on the surface of the thrust flange 9 facing the bearing member 16.

In the rotating head assembly configured as described above, since the spherical portion 162 of the bearing member 16 is in contact with the conical recess 502 of the fixed shaft 5A, the thrust flange 9 and the flat surface 162 of the bearing member 16 are in contact with each other.
Even if they are located at an angle with respect to each other before assembly, after assembly the rotary cylinder 2 and thus the thrust flange 9 rotates so that the bearing medium 10 is interposed between it and the flat surface 161 of the bearing member 16. After forming the thrust fluid bearing, the self-aligning action of the spherical portion 162 of the bearing member 16 allows the thrust flange 9 and the flat surface 161 of the bearing member 16 to maintain a stable state in which the pressure (dynamic pressure) of the bearing medium 10 is balanced. By forming a positional relationship, a highly accurate lubrication state in the thrust direction can be obtained. Therefore, the conical recess 50 of the fixed shaft 5A
2. The processing accuracy of the thrust flange 9 and the bearing member 16 does not need to be as high as the conventional one.

In addition, the thrust flange 9 or the bearing member 16
If the center axis 164 of the spiral groove 163 formed on the flat surface 161 of the rotary head is misaligned with the rotation center axis 17 of the thrust flange 9, the conventional rotating head assembly shown in FIG. A misalignment occurred between the maximum point 18 of the dynamic pressure generated by fluid lubrication on the bearing surface and the rotation center axis 17 of the thrust flange 9, resulting in deterioration of rotation accuracy. Even if there is such a misalignment, the bearing member 16
Due to the self-aligning action of the spherical portion 162, the maximum dynamic pressure point 18 on the thrust bearing surface is
Since it is stable at the point where the rotation center axis 17 of the thrust flange 9 and the rotation center axis 17 of the thrust flange 9 coincide with each other, it is possible to further improve the rotation accuracy.

Note that in order for the self-aligning action of the bearing member 16 to operate, it is necessary for the bearing member 16 to move from the initial state to a more stable position. A component of the dynamic pressure (thrust bearing surface pressure) acting on the flat surface 161 in the direction of inclination of the conical recess 502 is generated at the contact portion between the spherical portion 162 of the bearing member 16 and the conical recess 502 in the direction of inclination. must exceed the frictional force of Therefore, making the frictional force smaller leads to effective use of the self-aligning effect of the bearing member 16. For that purpose, the fixed shaft 5A
The inclination of the conical recess 502 is preferably less than 30 degrees with respect to the central axis in the longitudinal direction of the fixed shaft 5A.

Furthermore, in order to obtain the effect of this invention, it is sufficient for the bearing member 16 to contact the conical recess 502 of the fixed shaft 5A with a spherical surface. As shown in FIG. 5, a flat surface 165 may be provided on the opposite side of the flat surface 161 of the bearing member 16. The shape shown in FIG. 5 is easier to process when providing the spiral groove 163 on the flat surface 161 by rolling or the like.

In addition, the thrust flange 9 or the bearing member 1
In addition to the shape shown in FIG. 3, the shape of the spiral groove formed on the flat surface 161 of FIG. 6 may be the shape shown in FIG. You can.

[Effect of idea]

As described above, according to this invention, a conical recess is provided at the end of the fixed shaft on the thrust flange side, and the spherical part of the bearing member is brought into contact with this recess, and the flat surface is made to face the thrust flange of the rotating cylinder. Since we have adopted a structure in which a thrust fluid bearing is formed between these flat surfaces and the thrust flange via a bearing medium, the desired rotation accuracy of the rotating cylinder can be achieved without increasing the machining accuracy of the fixed shaft, thrust flange, etc. This makes it possible to reduce the cost of individual parts.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view of one embodiment of this invention;
The figure is an enlarged view of the main part of the embodiment shown in Fig. 1, Fig. 3 is a plan view showing the shape of the spiral groove formed in the bearing member in the embodiment shown in Fig. 1, and Fig. 4 is the embodiment shown in Fig. 1. Figure 5 is a sectional view showing the main part of another embodiment of this invention, Figure 6 is a diagram showing another shape of the spiral groove, and Figure 7 is a diagram showing an example of the dynamic pressure distribution on the thrust bearing surface. 8 is a sectional view of a conventional rotary head assembly, and FIG. 8 is a diagram showing the dynamic pressure distribution on the thrust bearing surface of the one shown in FIG. 7. In the figure, 1 is a recording/reproducing head, 2 is a rotating cylinder, 4 is a fixed cylinder, 401 is a lead groove, and 5 is a rotary cylinder.
A is a fixed shaft, 502 is a conical recess, 9 is a thrust flange, 16 is a bearing member, 161 is a flat surface,
162 is a spherical part, 163 is a radial groove, 1
65 is a plane. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims for Utility Model Registration] (1) A rotary cylinder that supports a recording/reproducing head, a fixed cylinder that has a lead groove on its outer circumferential surface that guides the running of the magnetic tape, and one end of which is fixed to the fixed cylinder and the other end of the cylinder. In a rotating head assembly of a magnetic recording/reproducing device comprising a fixed shaft forming a thrust fluid bearing between the rotary cylinder and the thrust flange, a cone is formed at the other end of the fixed shaft to face the thrust flange. a bearing member having a shaped recess, a flat surface facing the thrust flange, and a spherical portion accommodated in the recess and in contact with the recess, between the flat surface of the bearing member and the thrust flange. A rotary head assembly for a magnetic recording/reproducing device, characterized in that the thrust fluid bearing is formed in the rotary head assembly. (2) A rotating head assembly for a magnetic recording and reproducing device according to claim 1, wherein a spiral groove is formed on a flat surface of a bearing member. (3) The rotating head of the magnetic recording and reproducing device according to claim 1, wherein the inclination of the conical recess at the other end of the fixed shaft is less than 30 degrees with respect to the central axis of the fixed shaft. assembly. (4) A rotating head assembly for a magnetic recording and reproducing device according to claim 1, wherein the bearing member has a flat surface on the opposite side to the flat surface thereof.