JPS63138517A - Rotary drum device for vtr - Google Patents

Abstract

PURPOSE:To obtain a stable screen with a simple constitution without developing a tortional resonance in the rotational direction by fixing the rotational part of a rotary drum device in one direction of a shaft. CONSTITUTION:A motor startor 10 is fitted to the lower drum 9 of the rotary drum device for a VTR, while a rotar magnet 12 is fitted to an upper drum 4. A flange 3 is integrally fitted to the rotary shaft 1, and a video head 5 is arranged on the flange 3. The upper drum 4 is regarded as a 1st rotational part, and a 2nd rotational part by the lower drum 9 where the motor startor 10 is arranged is provided, facing the magnet 12 in the 1st rotational part. The 2nd rotational part is fitted to the rotary shaft 1 through bearings 6 and 7. Such a constitution is adopted that no rotational member is fitted on the lower part of the rotary shaft 1, and the moment of inertia of the drum device is set to zero. A resonance frequency is set infinite to make the size of the entire drum thin, thereby obtaining a stable image.

Description

DETAILED DESCRIPTION OF THE INVENTION [Minute hand for industrial use] This invention relates to a rotating drum device for a VTR (video tape recorder).

[Conventional technology]

A conventional rotary drum device for a VTR of this type was constructed as shown in FIGS. 2 and 3.

That is, in FIGS. 2 and 3, 1 is a rotating shaft, 2 is a rotary transformer on the rotating side that is fixed by adhesive or the like to a flange 3 that is integrally attached to the rotating shaft 1, and 4 is a rotary transformer that is attached to the flange 3. A drum, 5 is a video head screwed to the upper drum 4, 6.7 is a bearing attached to the rotating shaft 1, 8 is a spring that applies preload to the bearing 6.7, and 9 is press-fitted or glued into the bearings 6 and 7. 10 is a motor stator screwed to the lower drum, 11 is an end ring attached to the rotating shaft 1, and 12 is a rotor magnet screwed to the end ring 11.

In this conventional device, when a current is applied to the coil of the motor stator 10, the rotor magnet 12 rotates and the rotating shaft 1
Torque is transmitted to the upper drum 4 via the video head 5.
rotates. If this is simplified structurally, as shown in FIG. 3, weights are attached above and below via the rotating shaft 1. Therefore, when a disturbance is applied as an excitation force, the structure resonates in the rotational direction. This resonant frequency can be expressed in a formula as shown in formula (1).

πGd- However, K-3213 ■Engineer: Upper drum, video head, rotary transformer,
Moment of inertia of the flange I2: Moment of inertia of the end ring and rotor magnet d: Shaft diameter G: Lateral rigidity of the shaft l: Effective length of the shaft, that is, the resonance frequency is the moment of inertia 11 from equation (1).
．． 12 and is inversely proportional to the axial effective length l.

[Problems that inventions are unlikely to solve]

In such a conventional device, there is a problem in that the upper and lower rotating members resonate in the rotational direction through the shaft, resulting in distortion on the reproduced screen. In order to eliminate this screen tilt, we are currently managing the moment of inertia of the upper and lower rotating members.
Although resonance is avoided in the rotational direction, this control must be performed for each model, and the number of types of drums inevitably increases.

This invention eliminates the drawbacks of conventional ones such as Yoto.

The purpose of this invention is to provide a structure that does not cause the screen surface to tilt even without managing the moment of inertia of the rotating member.

[Means for solving problems]

A rotary drum device for a VTR according to the present invention has a rotor magnet arranged in a first rotating part which is attached to a rotating shaft and is provided with a video head, and a motor stator arranged opposite to this rotor magnet is attached to a rotating shaft. It is attached to the second rotating part which is mounted via a bearing on the rotor.

[Effect]

Since the rotating part in this invention is disposed only on one side of the bearing, vibrations in the rotational direction that cause the screen surface to curl do not occur, and it becomes necessary to manage the moment of inertia, which was necessary in the past.

〔Example〕

An embodiment of the present invention will be described below based on the drawings. That is, in FIG. 1, 10 is a motor stator attached to the lower drum 9, and 12 is a rotor magnet directly attached to the upper drum 4. The rest of the structure is the same as the conventional one shown in FIG. 2, so the explanation will be omitted. In this way, since the structure is such that no rotating member is attached to the lower part of the rotating shaft 1, the moment of inertia of equation (1)
2 becomes zero, the resonance frequency f becomes infinite, and basically resonance in the rotational direction does not occur even if a forcing force is applied. Furthermore, the entire drum can be made thinner.

Although the rotor magnet 12 is fixed to the upper drum 4 here, it may be attached to the flange 3.

Further, the same effect can be obtained by arranging the rotor magnet 12 on the upper drum 4 and further arranging the motor stator 10 on top of the rotor magnet 12 instead of incorporating the motor stator 10 in the lower drum 9.

〔Effect of the invention〕

As described above, according to this invention, all rotating parts are fixed to one side of the shaft, so torsional resonance in the rotational direction does not occur, eliminating the need to manage the moment of inertia that was previously required, and providing stable The performance is improved, such as by being able to obtain a brighter screen.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view showing a conventional rotary drum device for a VTR of this type, and FIG.
The figure is an explanatory view of the operation of the thing shown in FIG. 2. In the figure, 1 is a rotating shaft, 2 is a rotary transformer, 3 is a flange, 4 is an upper drum, 5 is a video head, 6.7 is a bearing, 9 is a lower drum, 1o is a motor stator, and 12 is a rotor magnet. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] a first rotating part attached to a rotating shaft and provided with a video head; a rotor magnet attached to the first rotating part; a motor stator disposed opposite to the rotor magnet; and a motor stator to which the motor stator is attached. A rotating drum device for a VTR, further comprising a second rotating section attached to the rotating shaft via a bearing.