Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2002-04-11
2004-05-11
Cao, Allen (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06735047
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a magnetic head and a magnetic recording/reproducing apparatus using the same. More specifically, the present invention relates to a magnetic head suitable for a high-definition VTR and digital VTR efficiently recording/reproducing a large amount of signals, a streamer recording/reproducing digital data, and the like and to a recording/reproducing apparatus using this magnetic head.
BACKGROUND ART
As a magnetic head with excellent high-frequency characteristics to be mounted on a videotape recorder (hereinafter, referred to as “VTR”), streamer, etc., a magnetic head has been developed that includes a magnetic core obtained by alternately laminating magnetic metal films and non-magnetic films. One example of such a magnetic head is a so-called multilayer magnetic head. The multilayer magnetic head includes magnetic core halves in which a laminated magnetic film, including soft magnetic metal films made of a Co-based amorphous alloy and non-magnetic films made of SiO
2
, is sandwiched between a pair of non-magnetic substrate materials and the magnetic core halves are arranged so that the end faces thereof oppose each other to form a magnetic gap therebetween. As the non-magnetic substrate materials, ceramics based on magnesium titanate, calcium titanate, or the like are used.
On the other hand, the VTR and streamer are getting smaller and more compact. Accordingly, a drum unit on which the magnetic head is mounted is being adapted to have a smaller size and higher rotational speed and a magnetic tape is being adapted to be thinner. For example, in a VHS-format VTR, the drum unit has a diameter of 62 mm and a relative velocity of 5.8 m/s and the magnetic tape has a thickness of about 18 &mgr;m. In contrast, in a DV (digital video)-format or DVCPRO-format VTR, the drum unit has a diameter of 21.7 mm and a relative velocity of 10 m/s or more and the magnetic tape has a thickness of 10 &mgr;m or less. The magnetic tape in the DV-format or DVCPRO-format is more susceptible to damage as compared with that in the conventional VHS-format or the like because its stiffness is reduced due to the reduction in thickness and the thickness of the magnetic layer is also reduced.
Further, in the VTR, there is a mode in which the magnetic tape is made to pause before recording/reproducing (hereinafter, referred to as “still mode”). During the still mode, the magnetic head is kept sliding on the same position of the magnetic tape. In a consumer VTR, to avoid damage to the magnetic head and magnetic tape, the VTR is designed so that the still mode is released or the tape tension is reduced after a certain period of time has elapsed from the time the still mode is started. However, in commercial and broadcast VTRs, the still mode may be maintained for a long time in preparation for news gathering or broadcasts, and in addition, it is required that a high-definition image is record/reproduced immediately after the still mode is released. Thus, there has been a demand for a magnetic recording/reproducing apparatus that does not damage the magnetic head or magnetic tape even when the still mode is maintained for a long time. In general, a still duration, which is the time required from the time the still mode is started until the reproduction output from the magnetic head decreases to a predetermined value, is used to evaluate still characteristics.
Examples of a conventional magnetic head using a non-magnetic single crystal All ferrite material include the one disclosed in JP 7(1995)-21513 A. This magnetic head is a multilayer magnetic head in which a non-magnetic single crystal ferrite material is used as a substrate material and the face orientation of the ferrite material at the sliding surface with respect to a magnetic tape is set to be {100}.
However, when the conventional multilayer magnetic head using a ceramic substrate is mounted on a high-speed rotary drum of the VTR or streamer, such problems occur as the magnetic head wearing considerably and having a short still duration.
Further, in a combination-type magnetic head in which two magnetic heads are mounted on one head base, there has been a problem in that the higher the relative velocity of the magnetic heads and magnetic tape, the greater the amount of wear in the magnetic head coming into contact with the tape first becomes as compared with that in the other magnetic head.
Furthermore, in the multilayer magnetic head using a non-magnetic single crystal ferrite substrate, when the crystal face orientation of the non-magnetic single crystal ferrite substrate at the sliding surface with respect to a magnetic tape is set to be {100}, there arises a problem of the magnetic head having a short still duration although the wear resistance thereof is improved.
DISCLOSURE OF INVENTION
Therefore, an object of the present invention is to provide a magnetic head that is less prone to wear and has a long still duration and a magnetic recording/reproducing apparatus including a high-speed rotary drum unit using the same.
In order to achieve the above object, a first magnetic head according to the present invention includes magnetic core halves, each including at least one magnetic film made of a soft magnetic metallic material and a pair of substrates sandwiching the magnetic film, arranged so that end faces thereof oppose each other with a magnetic gap being formed therebetween to form a magnetic path by the magnetic film in each of the magnetic core halves, wherein at least a part of a sliding surface of each substrate with respect to a magnetic tape is made of a non-magnetic single crystal ferrite material, a crystal face orientation of the non-magnetic single crystal ferrite material at the sliding surface is approximately {110}, and a <110> direction of the non-magnetic single crystal ferrite material is approximately in parallel with a sliding direction of the magnetic head with respect to the magnetic tape.
In order to achieve the above object, a second magnetic head according to the present invention includes magnetic core halves, each including at least one magnetic film made of a soft magnetic metallic material and a pair of substrates sandwiching the magnetic film, arranged so that end faces thereof oppose each other with a magnetic gap being formed therebetween to form a magnetic path by the magnetic film in each of the magnetic core halves, wherein at least a part of a sliding surface of each substrate with respect to a magnetic tape is made of a non-magnetic single crystal ferrite material, a crystal face orientation of the non-magnetic single crystal ferrite material at the sliding surface is approximately {110}, and a <100> direction of the non-magnetic single crystal ferrite material is approximately in parallel with a sliding direction of the magnetic head with respect to the magnetic tape.
In order to achieve the above object, a third magnetic head according to the present invention is a magnetic head in which at least one first magnetic head and at least one second magnetic head described above are mounted on one head base.
In this third magnetic head, it is preferable that the second magnetic head is arranged so that it comes into contact with a magnetic tape prior to the other magnetic head.
In order to achieve the above object, a first magnetic recording/reproducing apparatus according to the present invention includes a rotary drum unit having the first magnetic head, and a guide and contact mechanism for guiding a magnetic tape into the rotary drum unit and keeping the magnetic tape in contact with outer peripheral surfaces of a fixed drum and a rotary drum.
In order to achieve the above object, a second magnetic recording/reproducing apparatus according to the present invention includes a rotary drum unit having the second magnetic head, and a guide and contact mechanism for guiding a magnetic tape into the rotary drum unit and keeping the magnetic tape in contact with outer peripheral surfaces of a fixed drum and a rotary d
Hasegawa Kenji
Muraoka Shunsaku
Natsui Akinaga
Osano Koichi
Takahashi Ken
Cao Allen
Merchant & Gould P.C.
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