JPS6336523Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a rotating magnetic head drum for a magnetic recording/reproducing device, and in particular, the structure of the fixed drum has been modified so that the drum can be turned with high precision to contribute to flattening the device. This invention relates to a rotating magnetic head drum.

The structure of a conventional rotating magnetic head drum is shown in FIG. In FIG. 1, reference numeral 2 denotes a rotating drum, which is fixed to a rotating support 3 which carries a video head 1 and rotates around a rotating shaft 4. As shown in FIG. Reference numeral 5 designates a fixed drum, on which an upper bearing 6a and a lower bearing 6b for supporting the rotating shaft 4 are mounted, and a stator core 7 on the lower part.
and the motor winding 8 are fixed. A rotating magnet 9 is arranged on the outer periphery of this stator core 7.
With respect to the structure of such a rotating magnetic head drum, when trying to flatten the rotating magnetic head drum due to the demand for miniaturization of magnetic recording/reproducing devices, the first step is to flatten the rotating magnetic head drum.
There is a limit to the flattening of the drum portion _HD shown in the figure due to the magnetic tape width and recording pattern, and therefore the motor portion _HM must be flattened. However, in the structure shown in FIG.
Since the bearing part protrudes downward for a long time, the length H _M of the motor part cannot be shortened and flattening cannot be achieved. Therefore, as shown in FIG. 2, it may be possible to move the central bearing part of the fixed drum upward (toward the rotating drum side) to shorten and flatten the motor. However, when the motor part of the fixed drum is flattened and shortened in this way, the lower bearing part will be located in the chuck part of the lathe during the fixed drum turning process, so the roundness of the inner diameter of the bearing fitting part will be affected. The problem is that it gets worse.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixed drum structure that solves the above-mentioned problems in flattening the motor section of a rotating magnetic head drum and maintains the turning accuracy of the fixed drum. In order to achieve the above object, the main point of the present invention is to provide an escape space in the outer shape of the part of the fixed drum where the bearing is mounted. It is designed so that it does not affect the inner diameter of the fixed drum to which it is attached.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows the rotating magnetic head drum of this embodiment. As mentioned earlier, the upper bearing 6a and the lower bearing 6b are moved in the direction of the rotating drum (upward in the figure), and the length of the motor section is is shortened to H _M ′. Figure 3 shows the fixed drum 10 in Figure 2.
In the figure, reference numeral 11 denotes an escape space provided outside the outer periphery of the bearing fitting portion 15 with a depth h. By setting the depth h so that l _B ≦ l _h , where l _B is the bearing fitting length and l _h is the depth of the escape space 11 measured from the end face of the bearing fitting part 15, the fixed drum The roundness of the inner diameter of the bearing fitting portion 15 is not deteriorated during the turning process in step 10. That is, FIG. 4 shows a state in which the turning chuck 12 is chucking the chuck portion 14 of the fixed drum 10 during turning, and the bearing fitting hole d is being turned by the boring tool 13. By providing the escape space 11 outside the outer periphery of the fitting part 15, the distortion caused by the turning chuck 12 does not affect the bearing fitting hole d, so that the roundness of the bearing fitting hole d is improved. Can be processed.

As explained above, according to the present invention, the fixed drum can be turned without deteriorating the roundness of the inner diameter of the bearing fitting part, thereby shortening the length of the motor part and flattening the rotating magnetic head drum. This makes it possible to downsize the magnetic recording/reproducing device.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a conventional rotating magnetic head drum, FIG. 2 is a vertical cross-sectional view of an embodiment of the rotating magnetic head drum according to the present invention, FIG. 3 is a vertical cross-sectional view of a fixed drum in this embodiment, and FIG. The figure is an explanatory diagram showing turning processing of the fixed drum. Explanation of symbols, 6a... Upper bearing, 6b... Lower bearing, 10... Fixed drum, 11... Escape space,
12... Turning chuck, 13... Boring bite, 14... Chuck part, 15... Bearing fitting part.

Claims (1)

[Scope of utility model registration request] A rotating magnetic head drum comprising a rotating drum carrying at least one or more magnetic heads, a bearing supporting the rotating shaft of the rotating drum, and a stationary drum having the bearing attached to its inner diameter. A rotating magnetic head drum characterized in that an escape space is provided outside the outer shape of a portion of the fixed drum in which a bearing is mounted.