JP2000030202A - Rotating drum type magnetic recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotating drum type magnetic recording and reproducing device facilitated in a dynamic balance adjustment by realizing a shield function, without requiring a shield plate of exclusive use, and thereby reducing the weight. SOLUTION: This device is a rotating drum type magnetic recording and reproducing device provided with a rotating drum 1 with recording and reproducing magnetic heads 2, 3 mounted on a circumferential part, and a recessed part 5 for accommodating circuit elements formed toward inside from the upper front face of the rotary drum 1. A circular printed circuit board 6 is mounted on the rotary drum 1 so as to close this recessed part 5. Circuit elements 7 are packaged on an undersurface of this printed circuit board 6, and accommodated in the recessed part 5. A conductor pattern extensively formed on the upper face of the printed circuit board 6 serves as a shield. A weight 13 for dynamic balance is selectively attached in the conductor pattern for this shield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a VTR (Video
The present invention relates to a rotating drum type magnetic recording / reproducing device used in a tape recorder).

[0002]

2. Description of the Related Art A conventional rotary drum type magnetic recording / reproducing apparatus for recording / reproducing information on / from a running magnetic tape,
For example, as shown in a plan view and a cross-sectional view in FIGS. 3A and 3B, a magnetic head 2 for recording and a magnetic head 3 for reproduction are mounted on a lower circumferential portion of an upper drum 1. The upper drum 1 faces a stationary lower drum (not shown) and rotates about a shaft 4. A concave portion 5 is formed from the upper surface of the upper drum 1 toward the inside, and a circular printed board 6 is accommodated in the concave portion 5. This printed circuit board 6
A plurality of circuit components 7 necessary for the circuit configuration are mounted on the upper surface of.

A rotor 8 of a rotary transformer is arranged below the upper drum 1 so as to rotate integrally with the upper drum 1. The stator (not shown) of the rotary transformer is integrated with the lower drum. The rotary transformer includes the lower drum 1 and the upper drum 1.
And to perform signal transmission between them in a non-contact manner. The signal transmission path on the upper drum 1 side is: rotor 8 / rotor terminal 9 / printed circuit board 6 / circuit component 7 / head terminal 10 /
The heads 2 and 3 are formed.

A shield plate 11 is arranged on the upper surface of the upper drum 1 so as to close the recess 5, and magnetically shields the printed circuit board 6 and the circuit components 7 from the outside. The shield plate 11 is a conductive member, and its peripheral edge is in electrical contact with the upper drum 1 at the peripheral edge 12. On the upper surface of the shield plate 11, a weight 13 for adjusting a dynamic balance during rotation of the upper drum 1 is mounted by selecting a weight and a position. 14 and 15 are screws for fixing the shield plate 11, and 16 and 17 are screws for fixing the printed circuit board 6.

[0005]

The conventional rotary drum type magnetic recording / reproducing apparatus shown in FIG. 3 uses the shield plate 11 as an independent part, so that the number of parts is large and the drum weight is increased. As a result, there arises a problem that it is difficult to adjust the dynamic balance by the weight 13. This is a problem to be solved by the present invention.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotary drum type magnetic recording / reproducing apparatus which realizes a shielding function without requiring a dedicated shield plate, thereby reducing the weight and easily adjusting a dynamic balance. And

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotary drum on which a recording / reproducing magnetic head is mounted on a circumferential portion, and a circuit component formed from the upper surface of the rotary drum toward the inside. A concave portion for storage, a circular printed circuit board mounted on the rotating drum so as to close the concave portion,
A circuit component mounted on the lower surface of the printed circuit board and housed in the recess; a conductive pattern for shielding formed entirely on the upper surface of the printed circuit board; This can be achieved by a rotating drum type magnetic recording / reproducing apparatus including a dynamic balance weight to be attached.

In an embodiment of the present invention, the printed circuit board has at least two layers of conductor patterns, a circuit component is mounted on the lowermost layer conductor pattern, and the uppermost layer conductor pattern is used for shielding. More specifically, the printed circuit board has four conductor patterns, circuit components are mounted on the lowermost conductor pattern, and the uppermost conductor pattern is used for shielding.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. FIGS. 1A and 1B are a plan view and a cross-sectional view showing an embodiment of a rotary drum type magnetic recording / reproducing apparatus according to the present invention. In this figure, the same parts as those in FIG. 3 are denoted by the same reference numerals, and detailed description is omitted.

The first point of the rotary drum type magnetic recording / reproducing apparatus shown in FIG. 1 which is different from that of FIG. 3 is that the printed circuit board 6 is not accommodated in the concave portion 5 of the upper drum 1, but is instead provided on the upper surface of the upper drum 1. It was installed. In response to this change in arrangement, the circuit component 7 is mounted on the lower surface of the printed circuit board 6 and accommodated in the recess 5.

A second difference is that a conductive pattern for shielding is formed on the entire upper surface of the printed circuit board 6 so that a conventional shield plate is not required. The printed board 6 according to the present invention has at least two layers of conductor patterns, for example, as shown in a sectional view in FIG. In the illustrated example, four conductor patterns P1 to P4 are stacked with dielectric layers D1 to D3 interposed therebetween. Among these, the uppermost conductive pattern P1 is used as a shield entire screen. The remaining conductor patterns P2 to P4 are all circuit patterns, and the circuit component 7 is mounted on the lowermost conductor pattern P4. P2 and P3 are interlayer circuit patterns.

The weight 13 for dynamic balance adjustment is mounted on the uppermost conductive pattern (shielding screen) P1 by selecting its position and weight. Since the lowermost conductor pattern P4 is a circuit pattern, its peripheral portion 1
9 is not in contact with the upper drum 1.

In the rotary drum type magnetic recording / reproducing apparatus having the above structure, the number of parts is reduced and the weight is reduced by the elimination of the exclusive shield plate. Therefore, the head structure is simplified, and the dynamic balance of the upper drum 1 by the weight 13 is easily adjusted.

[0014]

As described above, according to the present invention, a rotary drum type magnetic material which realizes a shield function without requiring a dedicated shield plate, thereby achieving weight reduction and easy adjustment of dynamic balance. A recording / reproducing device can be realized.

[Brief description of the drawings]

FIG. 1 is a plan view and a sectional view showing an embodiment of a rotary drum type magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a sectional view showing an example of a printed circuit board according to the present invention.

FIG. 3 is a plan view and a sectional view showing an example of a conventional rotary drum type magnetic recording / reproducing apparatus.

[Explanation of symbols]

 Reference Signs List 1 rotating drum (upper drum) 2 magnetic head for recording 3 magnetic head for reproduction 4 shaft 5 recess 6 printed circuit board 7 circuit component 13 weight P1 uppermost conductor pattern (for shielding) P4 lowermost conductor pattern (for component mounting)

Claims (3)

[Claims] 1. A rotating drum on which a recording / reproducing magnetic head is mounted on a circumferential portion, a concave portion for accommodating circuit components formed from an upper surface of the rotating drum toward the inside, and a closed concave portion. A printed circuit board mounted on the rotating drum, a circuit component mounted on the lower surface of the printed circuit board and housed in the recess, and a shielding conductor formed entirely on the upper surface of the printed circuit board A rotating drum type magnetic recording / reproducing apparatus, comprising: a pattern; and a dynamic balance weight selectively attached on the shield conductive pattern. 2. The printed circuit board according to claim 1, wherein the printed circuit board has at least two layers of conductive patterns, a circuit component is mounted on the lowermost conductive pattern, and the uppermost conductive pattern is used for shielding. Rotary drum type magnetic recording / reproducing device. 3. The printed circuit board has four layers of conductive patterns, and a circuit component is mounted on the lowermost conductive pattern.
3. The rotating drum type magnetic recording / reproducing apparatus according to claim 2, wherein the uppermost conductor pattern is used for shielding.