JPH0973616A - Rotary magnetic head device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise generated due to the vibration of a printed circuit board caused by the switching of a motor by providing a thin film circular sheet of a nonmagnetic material which is heavier than the printed circuit board at least on one side surface of the printed circuit board. SOLUTION: The printed circuit board 8 is disposed between a back yoke 7 to be integrally rotated with a rotary drum and a magnet 62 via minute gaps from them respectively. The printed circuit board 8 is laminated with a frequency generator coil, a PG(phase detecting signal generator) coil and a driver coil in three layers, and is fixed on a supporting shaft 1. The thin film circular sheet of a nonmagnetic material having larger specific gravity than the printed circuit board 8 and a window hole 82 in a central part is stuck at least on one side surface of this printed circuit board 8. Consequently, a damper effect is imparted to the printed circuit board 8 while an increase of the thickness of a DD motor is suppressed, thus reducing vibration of the printed circuit board 8 due to a switchover of the motor and noise to be generated by the vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a VTR integrated with a camera.
Etc. to a rotary magnetic head device with a built-in motor.

[0002]

2. Description of the Related Art A conventional ultra-compact rotary magnetic head device in a VTR or the like with a built-in camera is required to be compact and lightweight. FIG. 3 shows a conventional rotary magnetic head device with a built-in DD motor, in which a bearing (41) (41) and a support cylinder (4) are attached to a support shaft (1) projecting from the shaft center of a fixed drum (2). Rotating drum through
(5) is rotatably arranged and the magnetic head is mounted on the rotating drum (5).
It has (51).

A fixed coil member (31) provided on the fixed drum (2) and a rotating coil member (32) provided on the support cylinder (4).
Are arranged close to each other to form a rotary transformer (3). The DD motor (6) includes an annular magnet (6) arranged concentrically with the rotary drum (5) via a rotary yoke (61).
2), an annular magnetic back yoke (7) fixed to the rotary drum (5) concentrically with the drum, a magnet (62) and a back yoke.
Support shaft with a small gap between them and (7)
(1) It is constituted by a printed circuit board (8) fixedly arranged on the above. The printed circuit board (8) is screwed and fixed to a mounting boss (9) which is press-fitted or shrink-fitted to the support shaft (1).

The magnet 62 has one or more pairs of magnetic poles. The printed circuit board (8) consists of a drive coil in a resin material,
The rotation detection coil and the position detection coil are formed in three layers,
The thickness is about 0.5 mm. Since the printed circuit board (8) is thin, the printed circuit board (8) itself vibrates at the switching frequency that occurs when the motor is switched, that is, when each phase of the motor is energized and switched between ON and OFF. Become.

Therefore, conventionally, as shown in FIG. 4, a ring (83) made of a non-magnetic material is adhered and fixed to the outer peripheral edge of the printed circuit board (8) to enhance the rigidity of the printed circuit board (8) and print. It is intended to reduce the vibration of the substrate (8). From the viewpoint of software driving, the motor driving of the driver IC is soft-switched so that the wave shape generated at the frequency during motor switching approaches a sine wave.

[0006]

[Problems to be Solved by the Invention] Current camera integrated type V
The rotary magnetic head device of TR has a high rotational speed of the magnetic head of 2700 rpm, and the vibration of the printed circuit board (8) can be reduced by attaching the ring (83). However, in the VTR with a built-in digital camera, which is expected to become the mainstream in the near future, the rotation speed of the magnetic head is 9
It is difficult to reduce the vibration of the printed circuit board (8) when the speed reaches 000 rpm, and the outer circumference of the printed circuit board (8) is reinforced by the ring (83) as in the conventional case to realize soft switching.
The present invention clarifies a rotary magnetic head device that can solve the above problems.

[0007]

In the rotary magnetic head device of the present invention, a rotary drum (5) having a magnetic head (51) and a fixed drum (2) are arranged on a support shaft (1), and the rotary drum (5) ), A magnet (62) having one or more pairs of magnetic poles between the back yoke (7) and the rotating drum (5), which rotate integrally with the rotating drum (5), and a frequency generator. A rotary magnetic head device in which an FG coil, a PG coil for generating a phase detection signal, and a driving coil are laminated in three layers and a printed board (8) fixed on a support shaft (1) is arranged with a minute gap therebetween. , A non-magnetic thin disk (81) having a window hole (82) in the center, which has a larger specific gravity than the printed circuit board (8) and is provided on at least one of the both surfaces of the printed circuit board (8). It is stuck and fixed.

[0008]

[Operation and effect] The printed circuit board (8) is provided with the printed circuit board.
A non-magnetic thin plate (81) having a larger specific gravity than (8) is attached and fixed to give a damper effect, suppressing an increase in the thickness of the DD motor, and suppressing the increase in the thickness of the DD motor. 2) and the noise generated by the vibration can be reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a portion of a rotary magnetic head device of the present invention, which is located above a rotary yoke (61).
Since the basic configuration is the same as that of the conventional example of FIG. 3, the configuration not described in the following description is as described in FIG. A rotary drum (5) mounted on a support shaft (1) via a bearing (41) and a support cylinder (4), and the rotary drum
A DD motor (6) is formed in the space between the annular back yoke (7) attached to (5).

The DD motor (6) has an annular magnet (62) arranged coaxially with the rotary drum (5) through a rotary yoke (61) and a rotary drum (5) coaxial with the drum. In the space between the back yoke (7), the magnet (62) and the back yoke (7), which are annular magnetic bodies fixed to the support shaft (1), there is a small gap between them. And a printed circuit board (8).

As is well known, the printed circuit board (8) has a FG coil for frequency power generation, a PG coil for power generation of a phase detection signal and a driving coil laminated in three layers and having a thickness of about 0.5 mm. The magnet (62) has one or more pairs of magnetic poles and has a thickness of about 1 mm.

A feature of the present invention is that a non-magnetic thin disk (81) having a thickness of about 0.3 mm is attached to at least one of both surfaces of the printed circuit board (8) to print. Board (8)
The point is that most of the In the embodiment, the disk (81) is attached to the upper surface of the printed circuit board (8), but it may be attached to the lower surface or both sides.

The non-magnetic thin disk (81) is a printed circuit board.
A material with a specific gravity larger than that of (8), for example, brass, lead, etc., is formed into a disc shape whose diameter is substantially the same as the diameter of the printed circuit board (8), and the electronic parts at the center of the printed circuit board are mounted in the center part. A window hole (82) is opened so as not to interfere with. Window hole
The diameter of the (82) is about 1/3 to 1/2 of the diameter of the disc, and the non-magnetic thin disc (81) covers most of the printed circuit board (8). The non-magnetic thin disk (81) is adhered to the printed board (8) with an adhesive.

On the printed circuit board (8), a non-magnetic thin disk (81) having a larger specific gravity than the printed circuit board (8).
It has a damper effect by attaching and fixing
It is possible to suppress an increase in the thickness of the D motor and reduce vibration of the printed circuit board (8) due to motor switching and noise generated by the vibration. The non-magnetic thin disk (81) has a thickness of about 0.3, and even if it is attached to both sides of the printed circuit board (8), the total thickness of the rotary magnetic head device is slightly increased. In particular, it does not hinder the small size.

The present invention is not limited to the configuration of the above embodiment, and various modifications can be made within the scope of the claims.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of the present invention.

FIG. 2 is a plan view of a printed circuit board.

FIG. 3 is a cross-sectional view of a conventional rotary head device.

FIG. 4 is an enlarged sectional view of a main part of the above.

[Explanation of symbols]

 (1) Support shaft (2) Fixed drum (5) Rotating drum (6) DD motor (7) Back yoke (8) Printed circuit board (81) Non-magnetic thin plate (9) Positioning boss

Claims (1)

[Claims] 1. A rotary drum (5) having a magnetic head (51).
The fixed drum (2) and the fixed drum (2) are arranged on the support shaft (1), and the back yoke (7) and the rotary drum that rotate together with the rotary drum (5).
A rotary drum having one or more pairs of magnetic poles between (5) and
A printed circuit board in which a magnet (62) rotating integrally with (5), an FG coil for frequency power generation, a PG coil for phase detection signal power generation, and a driving coil are laminated in three layers and fixed on a support shaft (1) ( In a rotary magnetic head device in which a small gap is provided between the printed circuit board (8) and the printed circuit board (8), at least one of the both surfaces of the printed circuit board (8) has a specific gravity larger than that of the printed circuit board (8) and a window hole (82) at the center. ) Opened non-magnetic thin disk (81)
Rotating magnetic head device that is attached.