Dynamic magnetic information storage or retrieval – Head – Head accessory
Patent
1984-04-20
1987-02-03
Wolff, John H.
Dynamic magnetic information storage or retrieval
Head
Head accessory
360 84, 36013022, 360102, 226 97, G11B 1560, G11B 5027
Patent
active
046412140
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a rotary head assembly of video tape recorder (hereinafter called VTR) and particularly pertains to a rotary head assembly of a type having its upper and lower cylinders secured in place on a fixed central shaft, which leads itself to ease of assembling, reduced power consumption and further stabler magnetic tape running.
BACKGROUND OF THE INVENTION
There are available various types of construction for a rotary head assembly of a VTR. For example, a basic type is constructed of two cylindrical bodies (hereinafter called cylinder) having nearly equal ODs which are arranged coaxially with each other.
FIG. 1 shows an example of the structure of a conventional rotary head assembly. Referring to FIG. 1, 1 denotes a rotary shaft, which is rotatably supported by bearings 2 and 3 which is rotationally driven by a driving motor (not shown in this figure). Magnetic head 4 is secured on the rotary shaft 1 through a member 5, to be rotated at a specified speed. Upper fixed cylinder 6 is bound coaxially to lower fixed cylinder 8 through a member 7 and the lower fixed cylinder 8 is, in turn, secured in position on a base of the VTR. Numerals 9 and 10 designate collars or sleeves and 11 a bearing retaining ring. The structure of the conventional rotary head assembly such as shown in FIG. 1 has defects as described hereunder:
(1) It is difficult to align the axial center of the upper fixed cylinder and that of the lower fixed cylinder at a desired accuracy.
(2) In the small rotary head assembly which is employed in a 8 mm type portable video camera having a camera and video tape recorder combined as a single unit, its cylinder diameter is reduced to about 2/3, and the magnetic tape width to 1/2, as compared with a conventional video rotary head assembly utilizing a 1/2 inch width magnetic tape, but its rotational speed is still the same as the conventional speed of 1,800 rpm. For this reason, in order to have an adequate running distance of the magnetic head on the magnetic tape per one TV picture frame, the angle that the running surface of the magnetic head makes with the running direction of the magnetic tape needs to be reduced from that in the conventional assembly. To effect this, the angle at which the magnetic tape is wound on the cylinders, which is approx. 190.degree. in the case of the conventional 1/2 inch tape must be increased to approx. 220.degree. in the 8 mm type camera. This makes impractical the upper cylinder fixing method such as shown in FIG. 1.
SUMMARY OF THE INVENTION
According to this invention, a rotary head assembly is provided having a member with a magnetic head which is turned in a gap between an upper and a lower fixed or stationary cylinder having nearly equal diameters arranged coaxially with each other and a magnetic tape which is helically wound around or runs on the peripheral surfaces of the aforementioned upper and lower fixed cylinders, the upper fixed cylinder being fixedly attached to a central shaft coaxially arranged therewith, for ease of assembling with high accuracy, reduced power consumption and more stable magnetic tape running.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front sectional view of a conventional rotary head assembly;
FIG. 2 is a front sectional view of a rotary head assembly embodying this invention; and
FIG. 3 is a bottom view of the upper fixed cylinder 17 of FIG. 2.
THE MOST PREFERABLE EMBODIMENT OF THIS INVENTION
FIGS. 2 and 3 present an embodiment of this invention. FIG. 2 is a sectional view of a rotary head assembly embodying this invention and FIG. 3 is a bottom view of its upper fixed cylinder.
Referring to FIG. 2, 12 denotes a fixed shaft having a central axis extending in an axial direction, 13 bearings, 14 a rotary member, 15 and 16 magnet and coil composing a direct drive motor which rotationally drive the rotary member 14 and on the respective lower axial end surface and the upper axial end surface of the upper fixed or stationary cylinder 17 and the lower fixed or stationary
REFERENCES:
patent: 3995317 (1976-11-01), Schmidt
patent: 4366516 (1982-12-01), Ogata et al.
patent: 4392168 (1983-07-01), Maruyama et al.
patent: 4455584 (1984-06-01), Heitmann
patent: 4525757 (1985-06-01), Imanishi et al.
Ichiyanagi Takashi
Imanishi Kiyokazu
Kishimoto Masaru
Naka Hiroyuki
Sakurai Yasuo
Garcia Alfonso
Matsushita Electric - Industrial Co., Ltd.
Wolff John H.
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