Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Drum record
Patent
1996-07-12
1998-06-02
Heinz, A. J.
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Drum record
360109, G11B 552
Patent
active
057610088
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a magnetic head device used in a magnetic recording and/or reproducing device such as video tape recorder (VTR) and its manufacturing method.
BACKGROUND OF THE INVENTION
Recently a magnetic recording and/or reproducing device such as VTR has come to be digitized for providing a high-quality image and sound and an increased dubbing performance. A trend for such higher recording data rate has led to a high density image recording by, for example, narrowing recording tracks and/or increasing the number of magnetic heads. Also, an endeavor has been undertaken to minimize the size of the device while improving its recording density and using a small-sized rotary drum.
FIG. 5 is a plan view showing a rotary drum of a conventional magnetic head device, in which the rotary drum is generally indicated by reference numeral 50. In this magnetic head device, a plurality of magnetic heads 51 to 56 are joined by adhesive onto the respective head bases 57 to 60, and each head base is in turn immovably mounted by screws (not shown) onto rotary drum 50. In addition, as shown in FIG. 6 which illustrates magnetic heads 51 and 53 viewed along the arrow B, each of magnetic heads 51 to 56 includes a track at its front surface. After magnetic heads 51 to 56 have been secured onto rotary drum 50, relative heights (e.g., H.sub.01, H.sub.02) of the tracks of magnetic heads 51 to 56 from certain reference levels in head bases 51 to 56 are adjusted by deforming the head bases in a known manner such as by turning an adjustment screw (not shown). In the meantime, each of magnetic heads 51 to 56 includes a small gap or slit defined at its front portion and an azimuth angle of the gap is adjusted to a predetermined angle.
In the above-described conventional magnetic head device, however, a multi-head structure having six magnetic heads supported on the four head bases is arranged on a rotary drum. Consequently, if the rotary drum has a small diameter, the magnetic head portions including head bases take relatively a large space on the rotary drum. This results in a restriction in joining the rotary portion to a rotor and also in connecting the magnetic head with a rotary transducer. Further, because of the space problem, it is even difficult to increase the number of the magnetic heads for a higher recording data rate.
In the meantime, in spite of the fact that the magnetic devices normally include a variation of approximate 20 micron meters in track height, a recent movement for reducing the width of tracks to, for example, 20 micron meters requires the relative track height between the magnetic heads (i.e., H.sub.02 minus H.sub.01) to be controlled as strictly as possible. Specifically, for the conventional magnetic head described above in which the track height in the magnetic head can be controlled by the head base, the relative track height should be kept under about five micron meters. Contrary to this, for the magnetic head having no fine adjustment mechanism for the track height in the magnetic head for lightening its head mass, such as an auto-tracking head using a bimorph piezo-electric-member, the relative track height should be kept under about two micron meters.
Therefore, in manufacturing the magnetic head device, firstly magnetic head 51 is glued onto head base 57, secondly among a number of magnetic heads a certain magnetic head 53 having a specific relative track height for the actual track height Ho.sub.1 is selected, and finally the selected magnetic head is adhered onto head base 57. Yet, in order to prepare the two magnetic heads to be paired, a great number of magnetic heads 53 should be stocked, normally about 5 to 10 times as many as magnetic heads 51, which results in an increase in stock of the magnetic heads.
Moreover, the magnetic head is a high value-added product which needs complicated machining in its production and is required to meet a number of standards with respect to, for example, head C/N, track width, azimuth angles, and interference fring
REFERENCES:
patent: 4151569 (1979-04-01), Hathaway
Fujiki Mitsuhisa
Omiya Takeshi
Heinz A. J.
Matsushita Electric - Industrial Co., Ltd.
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