JP2684700B2 - Rotating magnetic head device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The rotary magnetic head device of the present invention will be described in accordance with the following items.

A. Industrial fields of use B. Overview of the invention C. Prior art [Fig. 6] D. Problems to be solved by the invention [Fig. 6] E. Means for solving the problems F. 1 to FIG. 5] a. Configuration [FIGS. 1 to 4] b. Action [FIG. 5] G. Effect of the invention (A. Field of industrial application) The present invention is a novel rotary magnetic head device. Regarding Specifically, in a motor-integrated rotary magnetic head device, it is possible to reduce the magnetic influence of the rotor magnet of the drum motor portion on the magnetic head without using a magnetic shield member, which contributes to downsizing of the rotary magnetic head device. It is intended.

(B. Outline of the Invention) In the rotary magnetic head device of the present invention, in the so-called motor-integrated rotary magnetic head device, the magnetic head is positioned on a line extending radially through the center of the magnetic pole of the rotor magnet when viewed in the rotation axis direction. By doing so, the position of the magnetic head is set to a position where the magnetic flux density of the leakage magnetic flux of the rotor magnet is the smallest, and by this, the fog phenomenon of the leakage magnetic flux of the rotor magnet on the magnetic head can be reduced. Is unnecessary, and it is also possible to dispose the rotor magnet and the magnetic head close to each other, which makes it possible to make the rotary magnetic head device extremely small.

(C. Prior art) [Fig. 6] In a device using a rotary magnetic head device such as a video tape recorder or a digital audio tape recorder,
A rotary magnetic head device integrated with a motor is often used because of a demand for downsizing and a demand for easy control.

FIG. 6 shows an example of such a motor-integrated rotary magnetic head device a.

Reference numeral b is a fixed drum fixed to a chassis (not shown), and a tape guide portion called a lead is provided on the outer peripheral surface thereof.

c passes through the center of the fixed drum b,
Is a rotation shaft rotatably supported by bearings d, d.

Reference numeral e is a rotary drum fixed to the upper end of the rotary shaft c, and supports a magnetic head f near its peripheral surface.

g is a drum motor, and has a stator portion h and a rotor portion i.
Consisting of The stator part h is composed of a support member j fixed to a chassis (not shown) and located below the fixed drum b, and a coil substrate 1 supported by the support member j and provided with a plurality of stator coils k, k. Become. Further, the rotor portion i is supported by a magnet case m whose center portion is fixed to the lower end portion of the rotating shaft c, and a rotor supported by the m magnet case m so as to face the stator coils k, k ,. It consists of a magnet n.

Then, by energizing the plurality of stator coils k, k, ... In a predetermined order, the rotor magnet n is rotated, and the rotation is transmitted to the rotating drum e via the rotating shaft c. The rotating drum e rotates.

(D. Problem to be Solved by the Invention) [FIG. 6] However, like the rotary magnetic head device a, the rotary drum e on which the magnetic head f is supported and the drum motor g.
And are located apart from each other with the fixed drum b in between, and
If there is a sufficient distance from each other, the rotor magnet n
There is almost no problem of fogging of the leakage magnetic flux of the magnetic head f.

However, in the case of further miniaturization, it is unavoidable that the drum motor and the magnetic head come close to each other, and further, the rotary magnetic head device disclosed in Japanese Patent Laid-Open No. 63-168803. As described above, a method of further miniaturizing the rotor unit of the drum motor by integrating the rotor unit with the rotary drum is also adopted.

When the rotor magnet of the drum motor and the magnetic head are extremely close to each other as described above, conventionally, in order to reduce the fogging of the leakage magnetic flux of the rotor magnet on the magnetic head, a magnetic shield member such as a magnetic shield plate is magnetically connected to the rotor magnet. Interposition with the head is performed.

However, interposing such a magnetic shield member increases the number of parts accordingly, and causes not only high cost and reduced reliability, but also a demand for downsizing, especially for reducing axial dimension. However, there is a problem that there is not enough room to arrange such a magnetic shield member.

(E. Means for Solving the Problems) In order to solve the above-mentioned problems, the rotary magnetic head device of the present invention is a rotary magnetic head device in which a drum motor is integrated. The magnetic head is positioned on a line extending radially through the center of the magnetic pole.

Therefore, in the rotary magnetic head device of the present invention, since the position of the magnetic head is the most sparse part of the magnetic flux density of the leakage flux of the rotor magnet, the fogging of the leakage flux of the rotor magnet on the magnetic head is extremely reduced. In addition, it is inexpensive and highly reliable and contributes to downsizing because it does not require extra parts for such purpose.

(F. Embodiment) [FIGS. 1 to 5] Hereinafter, details of the rotary magnetic head device of the present invention will be described according to embodiment 1 shown in the drawings.

The first embodiment applies the present invention to an upper drum rotating type rotary machine head device in a magnetic recording / reproducing apparatus such as a video tape recorder or a digital audio tape recorder.

(A. Configuration) [FIGS. 1 to 4] 2 is a support shaft, which is erected on a chassis (not shown).

Reference numeral 3 denotes a fixed drum fixed to the lower end of the support shaft 2, a tape guide portion (not shown) is formed on the outer peripheral surface, and a large circular concave portion 4 is formed on the upper surface.
An upward step portion 4a is formed in the middle portion of the.

Reference numeral 5 denotes a rotary drum, which comprises a rotary support 6 rotatably supported by the support shaft 2 and a drum body 7 supported by the rotary support 6.

The rotary support 6 is formed by integrally forming a circular tubular boss portion 8 and a support flange 9 projecting from a position slightly lower than the center of the boss portion 8, and the boss portion 8 via bearings 10 and 10. It is rotatably supported by the support shaft 2. And the boss 8
The portion below the flange 9 is located in the portion below the step 4a of the recess 4 of the fixed drum 3, and the flange 9 is located in the portion above the step 4a of the recess 4.

The drum body 7 is formed into a bottomed cylindrical shape having a short axial length by a bottom plate 11 and a peripheral wall 12 provided upright from the peripheral edge of the bottom plate 11, and an insertion hole 13 is formed in the center of the bottom plate 11. . Further, on the lower surface of the peripheral edge portion of the bottom plate 11, there are formed six notches 14, 14, ... Formed at substantially equal intervals in the circumferential direction and open to the outer surface.

The notches 14 and 1 formed in the bottom plate 11 of the drum body 7
Head substrates 16, 16, ... With magnetic heads 15, 15, .. Incidentally, one of these magnetic heads 15 'is a dummy head for balancing.

In the drum body 7 as described above, the portion above the support flange 9 of the boss portion 8 of the rotary support body 6 is inserted through the insertion hole 13 at the center, and the bottom plate 11 is placed on the support flange 9. In that state, it is fixed by screwing or the like.

Reference numeral 17 denotes a drum motor, which includes a rotor portion and a stator portion.

Reference numeral 18 denotes a rotor portion, which is composed of the above-described rotary drum 5, rotor magnet, magnet case, and the like.

Reference numeral 19 denotes a magnet case fixed inside the rotary drum 5, and a donut-shaped rotor magnet 20 is fixedly supported on the upper surface of the magnet case 19. Then, the rotor magnet 20 is equally divided into a plurality of fan-shaped portions in the circumferential direction (in this embodiment, 12 equal portions), and each fan-shaped portion is magnetized so as to have different polarities alternately, so that the magnetic poles 21, 21 ', 21, twenty one',
Are formed. Or each magnetic pole 21, 21 ', 2
The upper surface and the lower surface of 1, 21 ', ... Have different polarities.

Then, the rotor magnet 20 and the magnetic head 1
The positional relationship between the magnetic poles 5, 15, ... When viewed in the axial direction of the support shaft 2, the lines 22, 22, radially extending through the centers of the magnetic poles 21, 21 ', 21, 21' ,. ... On top of magnetic heads 15, 15,
... is located.

Reference numeral 23 denotes a stator portion, which has a thin disk shape, and has a hole 24 formed in the central portion. The stator part 23 is an insulating substrate 25.
And a circuit pattern 26 formed on the upper surface of the insulating substrate 25.
And a coil pattern 27 formed on the lower surface of the insulating substrate 25,
27, ... and. This coil pattern 27, 27, ...
.. The specific pattern is the same as that of the known one, and the coil patterns 27, 27, ... Are connected to the rotating pattern 26, and the coil pattern is connected via the circuit pattern 26 by a control circuit (not shown). The energization control for 27, 27, ... Is performed.

Reference numeral 28 denotes a support body fixed to the upper end of the support shaft 2, and a flange 30 is integrally formed on the lower half of the boss portion 29,
The upper end of the support shaft 2 is press-fitted into a hole 31 that penetrates the boss portion 29 in the axial direction.

Then, the stator portion 23 is fixed to the support body 28 with its center hole 24 fitted onto the upper half portion of the boss portion 29 of the support body 28.

Then, the coil patterns 27, 27 of the stator portion 23, ...
Is opposed to the upper surface of the rotor magnet 20 of the rotor portion 18 in parallel with a slight gap.

Reference numeral 32 is a doughnut-shaped rotor yoke, the outer peripheral edge of which is fixed to the upper end surface of the peripheral wall 12 of the rotating drum 5, and is opposed to the rotor magnet 20 in parallel with the stator portion 23 interposed therebetween. There is.

Reference numeral 33 denotes a rotary transformer for transmitting and receiving signals between the rotary drum 5 and the fixed drum 3. The rotary transformer 33 is provided on the upper surface of the fixed drum 3 and on the lower surface of the rotary drum 5. And a supported rotor coil portion 35.

(B. Action) [FIG. 5] In the rotary magnetic head device 1, the coil pattern 27 of the stator portion 23 is controlled by controlling the energization of the coil patterns 27, 27 ,.
The rotary drum 5 is rotated by the relative movement force generated between the rotor magnets 27, ..., And the magnetic heads 15, 15 ,.

As can be seen from the magnetic flux diagram of FIG. 5, the position on the line 22 is the sparsest portion of the density of the leakage magnetic fluxes 36, 36, ... ,
Fogging of the magnetic heads 36, ... On the magnetic heads 15, 15 ,.

(G. Effects of the Invention) As is apparent from the above description, the rotary magnetic head device of the present invention includes a rotary drum, a rotary drum that is rotatable with respect to a fixed drum, and includes a magnetic head, A plurality of divided areas in the circumferential direction are magnetized so as to have alternating polarities alternately in the circumferential direction and have a fixed relationship with the fixed drum and the rotor magnet that rotates integrally with the rotary drum. A rotary magnetic head device including a drum motor having the rotor magnet and a stator coil facing the rotor magnet, wherein the magnetic head is on a line extending radially through the center of the magnetic pole of the rotor magnet when viewed in the rotation axis direction. It is characterized by being located.

Therefore, in the rotary magnetic head device of the present invention, since the position of the magnetic head is the most sparse part of the magnetic flux density of the leakage flux of the rotor magnet, the fogging of the leakage flux of the rotor magnet on the magnetic head is extremely reduced. In addition, it is inexpensive and highly reliable and contributes to downsizing because it does not require extra parts for such purpose.

In the description of the above embodiment, the present invention is applied to the rotary magnetic head device of the shaft fixed type, that is, the type in which the rotary drum and the rotor portion of the drum motor are rotatably supported by the support shaft fixed to the chassis. However, it does not mean that the application target of the present invention is limited to such a thing. For example, it may be applied to a rotary magnetic head device of a shaft rotation type, that is, a type in which a rotor of a rotary drum and a drum motor is fixedly supported by a rotary shaft that is rotatable with respect to a fixed drum. Such a thing is also included in the technical scope of the present invention.

[Brief description of the drawings]

1 to 5 show an embodiment of the rotary magnetic head device of the present invention. FIG. 1 is an exploded perspective view, FIG. 2 is a longitudinal sectional view, and FIG. 3 is a magnetized state of a rotor magnet. FIG. 4 is a perspective view of a visually important portion, FIG. 4 is a plan view visually showing a positional relationship between magnetic poles of a rotor magnet and a magnetic head, and FIG. 5 is a portion visually showing a state of leakage magnetic flux of a rotor magnet. FIG. 6 is an enlarged plan view, and FIG. 6 is a longitudinal sectional view showing an example of a conventional rotary magnetic head device. Explanation of symbols 1 ... Rotary magnetic head device, 3 ... Fixed drum, 5 ... Rotary drum, 15 ... Magnetic head, 17 ... Drum motor, 20 ... Rotor magnet, 21, 21 '... Rotor magnet Magnetic pole, 22 ...... A line that extends radially through the center of the magnetic pole of the rotor magnet, 27 ...... Stator coil

Claims (1)

(57) [Claims] 1. A fixed drum, a rotating drum rotatable with respect to the fixed drum and provided with a magnetic head, and areas divided into a plurality of portions in the circumferential direction alternately having opposite polarities in the circumferential direction. A rotating magnetic head including a rotor magnet that is magnetized and rotates integrally with the rotating drum, and a drum motor that has a fixed relationship with the fixed drum and that has a stator coil facing the rotor magnet. A rotary magnetic head device, characterized in that the magnetic head is located on a line that extends radially through the center of the magnetic poles of the rotor magnet when viewed in the direction of the rotation axis.