JPH0522964B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a video tape recorder (hereinafter referred to as VTR).
The invention relates to rotary head assemblies such as

[Conventional technology]

An example of a rotary head assembly using a hydrodynamic bearing in a conventional VTR is shown in FIG. In FIG. 2, reference numeral 1 denotes a head for recording and reproducing information on a magnetic tape, and this head is attached to a rotating cylinder 2. The rotating cylinder 2 is fixed to a radial flange (bearing housing) 7 with screws. 3 is a fixed cylinder, and a lead is formed on its outer peripheral surface to guide the running of the tape. A fixed shaft 4 is fixed to the fixed cylinder 3.
This fixed shaft 4 has spiral grooves 5 and 6 formed on its upper and lower outer peripheries, and constitutes a radial fluid bearing with a radial flange 7 via a bearing medium 8. It is a fluid lubricated part. Further, a bearing member 16 having a spherical surface is located in contact with a conical recess on the opposite side of the fixed portion between the fixed shaft 4 and the fixed cylinder 3, and the bearing member 16 or thrust flange (bearing housing) 9 has a spiral groove formed therein (not shown), and the bearing member 16 and the thrust flange 9 are connected to the bearing medium 10.
to form a thrust fluid bearing. Also,
The thrust flange 9 is fixed to the radial flange 7 by screws. The radial flange 7 is provided with a horizontal hole 17 penetrating the outer periphery, and this horizontal hole 17 is used to insert the fixed shaft 4 into the radial flange 7 to which the thrust flange 9 is fixed with screws during the assembly process. This is for discharging the air sealed in the space formed by the flange 7 and the thrust flange 9 to the outside. Further, the radial flange 7 is provided with a rotary transformer 11 on the rotating side of a cylindrical rotary transformer that transmits, receives, and amplifies signals.
is fixed by adhesive or other method. In addition, the fixed side rotary transformer 12 that is paired with this is,
It is fixed to the fixed cylinder 3 by gluing or screwing. 13 is a rotor magnet of the drive motor; 14 is a rotor magnet of the drive motor bonded to a rotor case 15; the rotor case 15 is fixed to the radial flange 7 by bonding or screwing.

[Problem that the invention seeks to solve]

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. However, the conventional rotary head assembly shown in FIG. 2 has the following drawbacks. In other words, a horizontal hole is required on the radial flange side to vent air during assembly and insertion.
The drawback was that machining this side hole was difficult and the cost of the parts increased.

The present invention has been made to solve the above-mentioned problems, and its object is to obtain a low-cost rotating head assembly using a fluid bearing.

[Means for solving problems]

The rotary head assembly according to the present invention is inserted into a bearing housing of a rotary cylinder, and the fixed shaft of the fixed cylinder, which together with the bearing housing constitutes a fluid bearing, has a through hole formed in the longitudinal direction of the shaft, and one end side of the fixed shaft. The radial fluid bearing has a structure in which the lateral hole opens into the through hole, and the other end thereof opens into a portion of the bearing housing other than the fluid lubrication portion of the radial fluid bearing.

[Effect]

In this invention, since the fixed shaft of the fixed cylinder has the above structure, when the fixed shaft of the fixed cylinder is inserted into the bearing housing of the rotary cylinder, the opening on the other end side of the horizontal hole of the fixed shaft is connected to the fluid lubrication part. At the point when the air inside the bearing housing is exposed inside the bearing housing, the air inside the bearing housing is exhausted from the opening on the other end side of the horizontal hole to the outside of the fixed shaft through the horizontal hole and the through hole that follows it, and the assembly is stopped. It can be done easily. Further, drilling holes in such a fixed shaft is relatively simple, and it is possible to reduce the manufacturing cost of the device.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 18 denotes a fixed shaft, and spiral groups 19 and 20 are formed on the upper and lower outer peripheries of the fixed shaft 18. The fixed shaft 18 also has a through hole 21 in the longitudinal direction of the shaft.
A horizontal hole 22 communicating with this through hole 21 is provided. Furthermore, the radial flange 7 does not require the conventionally provided horizontal hole 17 as shown in FIG. Note that the components other than the fixed shaft 18 and the radial flange 7 are the same as the conventional example shown in FIG. 2, so the explanation will be omitted.

Next, a process for assembling the rotary head assembly constructed as described above will be explained.

When the fixed shaft 18 is inserted into the radial flange 7 to which the thrust flange 9 is fixed with screws, the air in the space created by the radial flange 7 and the thrust flange 9 is released from the horizontal hole 22 provided in the fixed shaft 18. It is discharged to the outside through the through hole 21. In this embodiment, since the fixed shaft is provided with a hole for discharging air necessary for the assembly process of the rotary head assembly, the hole can be easily machined.

〔Effect of the invention〕

As described above, according to the rotary head assembly according to the present invention, the fixed shaft of the fixed cylinder inserted into the bearing housing of the rotary cylinder has a through hole formed in the longitudinal direction of the shaft, and one end side is inserted into the through hole. The opening is open and the other end is inside the bearing housing.
Since the radial fluid bearing has a structure with a horizontal hole opened in a part other than the fluid lubrication part, during assembly, the air inside the bearing housing is exhausted through the through hole and the horizontal hole of the fixed shaft. As a result, there is no need to form air exhaust holes on the bearing housing side, which is difficult to machine, and there is an effect that machining costs can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a rotary head assembly using a liquid bearing for a VTR according to an embodiment of the present invention;
FIG. 2 is a sectional view of a rotary head assembly using a conventional VTR hydrodynamic bearing. 1...recording/reproducing head, 2...rotating cylinder, 3...
Fixed cylinder, 7... Radial flange (bearing housing), 8, 10... Bearing medium, 9... Thrust flange (bearing housing), 18... Fixed shaft, 19
... Upper radial spiral group, 20... Lower radial spiral groove, 16... Bearing member,
21...Through hole, 22...Horizontal hole. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A rotary cylinder having a bearing housing that supports a recording/reproducing head, and a fixed cylinder having an outer circumferential surface serving as a guide surface for tape running and having a fixed shaft fixed to the fixed shaft. In the rotary head assembly, the rotary cylinder is rotatably supported relative to the fixed cylinder by being inserted into the bearing housing, and the bearing housing has a spherical portion located in contact with the recess at the tip of the fixed shaft. A thrust fluid bearing is configured together with the bearing member, and a radial fluid bearing is configured together with the fixed shaft. A rotary head assembly characterized in that it has a side hole that opens into the hole, and the other end of which opens into a portion of the bearing housing other than the fluid lubricating portion of the radial fluid bearing.