JP2772144B2 - Rotary drum device for magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary drum device provided with a rotary transformer in a magnetic recording / reproducing apparatus such as a VTR.

[0002]

2. Description of the Related Art As shown in FIG. 5, a conventional magnetic recording / reproducing apparatus includes an upper drum 1 as a rotating drum and a lower drum 2 as a fixed drum, and a magnetic head 3 is mounted on the upper drum 1. Have been. The lower drum 2 is provided with a stator 5 of a drum motor 4, the cover 6 is provided with a rotor 7 of the drum motor 4, and the upper drum 1 is driven by the drum motor 4 via a collar 8, a shaft 9 and a disk 10. Is to be rotated.

The magnetic head 3 on the upper drum 1 side and the lower drum 2
The stator 12 of the rotary transformer that transmits signals between the lower drum 2 and the mounting surface 13a of the stator 12 in the rotary transformer, and the mounting end surface 12b of the stator 12 is fitted to the lower drum 2. And is attached to the lower drum 2 by being brought into contact with the end face 13a of the lower drum 2. On the other hand, the rotor 14 in the rotary transformer
Is arranged concentrically with the stator 12 and has its mounting surface 14
a is fitted to the fitting surface 10a of the disk 10,
The mounting end surface 14b is positioned by contacting the end surface 10b, and is mounted on the disk 10.

[0006] As shown in FIG. 6, the gap forming surface 12 c which is the outer peripheral surface of the stator 12 usually has a winding groove 1.
5 and 15 and a plurality of short ring grooves 16 are formed. As shown in FIG. 7, the gap forming surface 14c which is the inner peripheral surface of the rotor 14 opposed to the gap forming surface 12c with a small gap therebetween usually has winding grooves 17 and 17 and a short ring groove. 18 are formed. Since the transmission loss between the rotor 14 and the stator 12 increases when the above-mentioned minute gap increases, the minute gap is usually set to about 60 to 70 μm. Therefore, the outer diameter D ₁ of the stator 12, the difference between the inner diameter D ₂ of the rotor 14, 12 twice the minute gap
It is set to about 0 to 140 μm.

[0005]

The stator 12 and the rotor 14 are composed of the lower drum 2 and the disc 1.
A minimum clearance of about 10 μm is required in order to be fitted into the zero fitting surfaces 2a and 10a. In addition, the variation of the outer diameter D ₁ of the stator 12 and the inner diameter D ₂ of the rotor 14 is about ± 10 μm, and the variation of the diameter of the lower drum 2 and the fitting surface 2a and 10a of the disk 10 is ± 5 μm.
m. Furthermore, the mounting surfaces 12a and 14a of the stator 12 and the rotor 14 and the gap forming surface 12
Assuming that the grinding with c and 14c is performed by another processing, the mounting surfaces 12a and 14a and the gap forming surface 12c
And the eccentricity with 14c is about 30 μm. Also, an eccentricity of about 10 μm occurs due to an error in the perpendicularity of the mounting end surfaces 12b and 14b of the stator 12 and the gap forming surface 14c with respect to the gap forming surfaces 12c and 14c.

When the above tolerances are combined, the minimum clearance (1
0 μm) + variation of outer diameter D ₁ and inner diameter D ₂ (± 10
μ = 20 μm) + variation of the diameter of the fitting surfaces 2a and 10a (± 5 μ = 10 μm) + eccentricity of the mounting surfaces 12a and 14a and the gap forming surfaces 12c and 14c (30 μm
■ 60μm in runout + eccentricity due to squareness error (10μ)
(m ■ 20 μm) and the total is 120 μm, and in the worst case, the minute gap between the stator 12 and the rotor 14 may be zero. Therefore, there is a case where a 70~80μm about the minute gap the difference between the outer diameter D ₁ and the inner diameter D ₂ as approximately 140～160Myuemu,
In that case, as described above, the rotor 14 and the stator 1
The problem that transmission loss between two becomes large cannot be avoided.

Therefore, the eccentricity between the mounting surfaces 12a and 14a and the gap forming surfaces 12c and 14c which occupy the largest ratio among the above-mentioned tolerances is suppressed (preferably by 10%).
It is desired that the mounting surfaces 12a and 14a and the gap forming surfaces 12c and 14c be simultaneously processed, respectively, in order to reduce the thickness to less than μm. However, this simultaneous processing has been extremely difficult. For example, to describe the stator 12 side, as shown in FIG. 8, the stator 12 is formed to be longer by ΔL in advance and an extension 12 d is provided, and the inner peripheral surface 12 e of the extension 12 d and the magnet chuck 20 are used. It is conceivable that the end surface 12f is chucked, the mounting surface 12a and the gap forming surface 12c are simultaneously ground by the grindstones 21 and 22, and the extension 12d is scraped off after the grinding. However, in that case, there is a problem that the number of steps is increased.

[0008]

According to the present invention, there is provided a rotating drum device for a magnetic recording / reproducing apparatus, which is provided in the magnetic recording / reproducing apparatus and has a rotating drum and a stator fitted to a fixed drum. A rotary drum device including a rotor fitted to a drum and having a rotary transformer in which the stator and the rotor face each other with a small gap between the gap forming surfaces thereof, wherein a gap forming surface of the stator and the rotor is provided. Cylindrical projections shorter than the axial lengths of the stator and the rotor are provided on the opposite surfaces, respectively, and these cylindrical projections are simultaneously formed with the gap forming surface so as to be substantially concentric with the gap forming surface. And that the mounting surface to be mounted on the fixed drum or the rotating drum is formed. It is an butterfly.

[0009]

According to the above construction, a cylindrical projection is provided on a part of the surface of the stator and the rotor opposite to the gap forming surface, and the mounting surface is simultaneously formed on the cylindrical projection when the gap forming surface is processed. With this configuration, the mounting surface can be formed substantially concentric with the gap forming surface. Note that chucking of the stator and the rotor at the time of machining the mounting surface and the gap forming surface can be performed at a portion other than the cylindrical protrusion on the surface opposite to the gap forming surface.

[0010] As described above, the stator and the rotor are fitted and mounted on the fixed drum and the rotating drum on the mounting surface formed substantially concentrically with the gap forming surface, so that the rotor and the stator are concentric. The degree improves. Therefore, the minute gap between the gap forming surfaces can be reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 2, a magnetic recording / reproducing apparatus such as a so-called helical scanning type VTR includes an upper drum 31 as a rotating drum and a lower drum 32 as a fixed drum. Is attached. The lower drum 32 is provided with a stator 35 of a drum motor 34, and the cover 36 is provided with a rotor 37 of the drum motor 34, and the upper motor 3 is driven by the drum motor 34 via a collar 38, a shaft 40 and a disk 41.
1 is rotated. The shaft 40 is rotatably supported by the lower drum 32 via bearings 42 and 43.

A rotary transformer 44 for transmitting a signal between the magnetic head 33 on the upper drum 31 side and the lower drum 32 (ie, an external circuit) includes a stator 45 and a rotor 47. The stator 45 has a mounting surface 45b of a cylindrical projecting portion 45a provided on the inner peripheral surface thereof and a clearance fit with a fitting surface 32a of the lower drum 32, and a mounting end surface 45c of the stator 45 contacts an end surface 46a of a mounting plate 46. It is positioned by contact and is attached to the lower drum 32.

The rotor 47 is arranged concentrically with the stator 45. The mounting surface 47b of the cylindrical projection 47a provided on the outer peripheral surface of the rotor 47 fits into the fitting surface 41a of the disk 41 with a clearance. 47c is positioned by being in contact with the end face 41b of the disk 41, and is attached to the disk 41.

As shown in FIG. 3, winding gaps 48.4 are formed on a gap forming surface 45d which is an outer peripheral surface of the stator 45.
8 and a plurality of short ring grooves 50 are formed.
The inner diameter of the inner peripheral surface 45e of the portion other than the cylindrical protrusion 45a of the stator 45 is larger than the inner diameter d ₁ of the cylindrical protrusion 45a.

On the other hand, as shown in FIG. 4, the rotor 47 in FIG. 2 is turned upside down, and a gap forming surface 47d which is an inner peripheral surface opposed to the gap forming surface 45d of the stator 45 with a small gap therebetween is provided. , A plurality of winding grooves 51, 51 and a plurality of short ring grooves 52. The outer diameter of the outer peripheral surface 47e of the portion other than the cylindrical protrusion 47a of the rotor 47 is smaller than the outer diameter d ₂ of the cylindrical protrusion 47a.

The stator 45 and the rotor 47
As an example, the outer diameter D ₁ of the stator 45 is 2
7.4 mm, the inside diameter of the part other than the cylindrical protrusion 45a is 23
mm, 22.5 mm inner diameter d ₁ of the cylindrical protrusion 45a, the total axial length 19 mm, an axial length of the portion other than the cylindrical protrusion 45a may be 16 mm. On the other hand, the outer diameter d ₂ of the cylindrical protrusion 47a of the rotor 47 32.
9 mm, the outer diameter of the portion other than the cylindrical projection 47a is 32.4.
mm, inner diameter D ₂ is 27.54 mm, and total axial length is 19
mm, the axial length of the part other than the cylindrical protrusion 47a is 16
mm. However, the above values are merely examples, and the sizes of the stator 45 and the rotor 47 can be changed with a considerable degree of freedom in actual manufacturing.

In manufacturing the stator 45, first,
After molding and sintering a powder such as Mn-Zn-Fe into a shape as shown in FIG. 1, the stator 45 is chucked by the magnet chuck 53 on the inner peripheral surface 45e and the end surface 45f opposite to the mounting end surface 45c. The mounting surface 45b and the gap forming surface 45d are simultaneously ground by the grindstones 54 and 55. At this time, the mounting end face 45c is simultaneously ground by a grindstone (not shown).

As described above, since the gap forming surface 45d, the mounting surface 45b, and the mounting end surface 45c are ground at the same time, the concentricity between the gap forming surface 45d and the mounting surface 45b can be as high as about 0.01 or less. And the accuracy of the perpendicularity between the mounting surface 45b and the mounting end surface 45c can be as high as about 0.01 or less. On the other hand, the inner peripheral surface 45e other than the cylindrical protrusion 45a does not need to be ground. The manufacture of the rotor 47 can be performed in the same manner as the manufacture of the stator 45.

As described above, in this embodiment, the gap forming surface 45d of the stator 45 and the rotor 47 is formed.
Since 47d and the mounting surfaces 45b and 47b, which are surfaces to be fitted to the lower drum 32 and the disc 41, are simultaneously ground, the concentricity between the gap forming surfaces 45d and 47d increases, and Gap forming surface 45d
The transmission gap of the rotary transformer 44 can be reduced by reducing the minute gap between 47d.

The stator 45 and the rotor 47
The mounting end surfaces 45c and 47c of
Since d and 47d and the mounting surfaces 45b and 47b are ground at the same time, the mounting end surfaces 45c and 47c and the mounting surface 4
The degree of perpendicularity to the gaps 5b and 47b is increased, and the eccentricity between the gap forming surfaces 45d and 47d due to the error in the perpendicularity is also reduced. Therefore, the minute gap between the gap forming surfaces 45d and 47d can be further reduced.

Further, at the time of grinding, the cylindrical protrusions 45a and 47
Since the stator 45 or the rotor 47 can be chucked by the inner peripheral surface 45e or the outer peripheral surface 47e other than a, it is not necessary to previously form the stator 45 or the rotor 47 longer for chucking. Further, since the inner peripheral surface 45e and the outer peripheral surface 47e other than the cylindrical protrusions 45a and 47a do not need to be ground, the number of processing steps can be reduced.

[0022]

As described above, the rotating drum device of the magnetic recording / reproducing apparatus according to the present invention has a structure in which the surfaces of the stator and the rotor on the side opposite to the gap formation surface are shorter than the axial lengths of the stator and the rotor, respectively. Are formed simultaneously with the gap forming surface so as to be substantially concentric with the gap forming surface, and a mounting surface to be attached to the fixed drum or the rotating drum is formed on each of the cylindrical protrusions. Configuration.

As described above, the cylindrical projections are provided on a part of the surface of the stator and the rotor opposite to the gap forming surface, and the mounting surface is formed on these cylindrical projections simultaneously with the processing of the gap forming surface. As a result, the mounting surface can be formed substantially concentrically with the gap forming surface. Note that chucking of the stator and the rotor at the time of machining the mounting surface and the gap forming surface can be performed at a portion other than the cylindrical protrusion on the surface opposite to the gap forming surface.

As described above, since the stator and the rotor are fitted and mounted on the fixed drum and the rotating drum on the mounting surface formed substantially concentric with the gap forming surface, the concentricity between the rotor and the stator is reduced. Since a small gap between the gap forming surfaces can be reduced, the transmission loss between the rotor and the stator can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a state of machining a stator according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a rotary drum device including the stator of FIG.

FIG. 3 is a longitudinal sectional view of a stator in the rotary drum device of FIG. 2;

FIG. 4 is a longitudinal sectional view of a rotor in the rotary drum device of FIG.

FIG. 5 is a longitudinal sectional view showing a conventional rotary drum device.

6 is a vertical sectional view of a stator in the rotary drum device of FIG.

FIG. 7 is a longitudinal sectional view of a rotor in the rotary drum device of FIG.

FIG. 8 is a longitudinal sectional view showing a state of processing the stator of FIG. 6;

[Explanation of symbols]

 31 Upper Drum (Rotating Drum) 32 Lower Drum (Fixed Drum) 44 Rotary Transformer 45 Stator 45a Cylindrical Projection 45b Mounting Surface 45d Gap Forming Surface 47 Rotor 47a Cylindrical Projection 47b Mounting Surface 47d Gap Forming Surface

Claims (1)

(57) [Claims] 1. A magnetic recording / reproducing apparatus comprising a stator fitted to a fixed drum and a rotor fitted to a rotating drum, wherein the stator and the rotor have a small gap between their gap forming surfaces. In the rotary drum device having a rotary transformer opposed to each other with a space therebetween, a surface of the stator and the rotor opposite to the gap forming surface is provided with a cylindrical protrusion shorter than the axial length of the stator and the rotor, respectively. The magnetic protrusion is formed at the same time as the gap forming surface so as to be substantially concentric with the gap forming surface, and has a mounting surface mounted on a fixed drum or a rotating drum, respectively. A rotary drum device for a recording / reproducing device.