Metal deforming – With cutting – By composite tool
Reexamination Certificate
2000-12-26
2002-05-07
Crane, Daniel C. (Department: 3725)
Metal deforming
With cutting
By composite tool
C029S603070, C029S603010
Reexamination Certificate
active
06382009
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for adjusting height of a magnetic head, such as a double azimuth type magnetic head which is assembled in a video tape recorder, for example.
The video tape recorder is provided with a cylinder head
52
, around an outer peripheral face of which a video tape
50
supported by means of guide pins
51
,
51
slidably runs, as shown in FIG.
4
. The video tape
50
slidably runs in a state where it is wound around the cylinder head
52
at a determined inclination angle and along a determined angular range with respect to the cylinder head
52
. A pair of double azimuth type magnetic heads (hereinafter referred to simply as “magnetic head”)
53
are mounted at an equal interval on the cylinder head
52
with their one portions exposed from the outer peripheral face of the cylinder head. Each of the magnetic heads
53
includes a printed board
54
, a pair of base plates
55
which are assembled to one side of the printed board
54
in a cantilever manner, and head chips
56
which are respectively attached to distal end portions of these base plates
55
, as shown in
FIGS. 5 and 6
.
The magnetic head
53
is assembled to the cylinder head
52
in such a manner that a sliding face
56
a
of the head chip
56
in which a magnetic gap G is formed (see
FIG. 7D
) is exposed outward from the outer peripheral face of the cylinder head
52
. The magnetic head
53
precisely records and reproduces, in a rotating state of the cylinder head
52
, recorded image information, audio information, and so on by helically scanning the video tape
50
which is slidably running around the outer peripheral face of the cylinder head at high speed. For this reason, it is necessary for the magnetic head
53
to locate the magnetic gap G of the head chip
56
precisely in a scope of some micron with respect to a recording track of the video tape
50
, as shown in FIG.
6
.
By the way, the magnetic head
53
varies in height because of variation in thickness of the head chips
56
due to slicing accuracy when the head chip
56
is manufactured, or pasting accuracy when this head chip
56
is pasted to the base plate
55
, and an adjusting operation of the height is required. In a related method for adjusting the height as disclosed in Japanese Patent Publication No. 8-55319A, for example, the height of the head chip
56
has been adjusted by varying flatness of the base plate
55
with respect to a reference plane.
After the above described adjusting operation has been conducted, a sliding face
56
a
of the head chip
56
in the magnetic head
53
is polished in order to give a favorable touch with the video tape
50
. This polishing process is conducted by mounting the magnetic head
53
on a polishing jig in a cylindrical shape like the cylinder head
52
and by driving a wrapping tape to run. The wrapping tape slidably runs at a determined inclination angle and a winding angle in a determined range, in the same manner as the video tape
50
, thereby polishing the sliding face
56
a
of the head chip
56
so as to give a desired curvature.
The height of the magnetic head
53
has been adjusted by bending and deforming the base plate
55
at a desired angle by means of a press member
62
and a push-up member
63
in a state where a base part of the base plate
55
is held between a holding table
60
and a press board
61
, as specifically shown in FIG.
7
A. The base plate
55
of the magnetic head
53
is bent and deformed by pushing up the push-up member
63
from below in a state where a projected portion of the base plate
55
is pressed from above by the press member
62
.
However, in such a related method for adjusting the height, the distal end portion of the base plate
55
is bent and deformed in an arcuate shape around a pressing position of the press member
62
, as shown in FIG.
7
B. As a result, the sliding face
56
a
of the head chip
56
will not be retained in parallel to the reference track plane. Accordingly, when the above described polishing process is applied to the sliding face
56
a
of the head chip
56
, an apex of a curvature r in a direction of thickness in an area near the track is displaced by an amount of &Dgr;x with respect to a center of the gap G, as shown in FIG.
7
C.
For this reason, a center P of magnetic interference fringes generated on the sliding face
56
a
of the head chip
56
is deviated from the center O of the magnetic gap G, as shown in FIG.
7
D. Such magnetic head
53
is inferior in recording and reproducing property for the image information and the audio information, because tape touch will be worsened when the magnetic head has been assembled to the cylinder head
52
, even though the above described height adjustment has been conducted.
SUMMARY OF THE INVENTION
In view of the above, an object of the invention is to provide a method for adjusting height of a magnetic head in which recording and reproducing property with higher accuracy can be obtained by simply conducting the height adjustment, while maintaining the sliding face of the head chip in parallel to a reference track plane.
In order to achieve the above object, according to the present invention, there is provided a method of adjusting a height of a head chip, which is attached to one end portion of a base plate to constitute a magnetic head, with respect to a reference plane of the base plate, comprising the steps of:
placing a face of the base plate which is to be the reference plane onto a first plane face of a die member; and
punching a punch member onto a predetermined portion of the base plate toward a diagonal direction with respect to the reference plane such that a portion of the base member on which the head chip is attached is shearing-deformed by a predetermined amount in the punching direction.
Preferably, the predetermined amount is set within a plastic deformable range of the base plate.
Preferably, the die member is provided with a second plane face extending orthogonally to the first plane face. The second plane face, the predetermined portion of the base plate and a shearing blade face of the punch member are arranged on an identical line.
Preferably, the deforming direction of the base plate is parallel with a sliding face of the head chip, which is to be slid on a recording medium.
In the above configurations, a shearing deformation process is conducted on the sliding face of the head chip while keeping a diagonal attitude thereof with respect to the reference plane. Accordingly, adjustment of the height is conducted in a state where the sliding face of the head chip and a reference track plane of the recording medium are kept in parallel to each other. Therefore, when the polishing process is applied to the sliding face of the head chip, the center of the curvature of the sliding face and the center of the magnetic gap are substantially aligned, to give a favorable tape touch, whereby a magnetic head which can carry out recording and reproduction with high accuracy can be manufactured. Further, the height adjustment with high precision can be simply performed, and necessity of assembling the magnetic head to a cylinder head employing various spacers will be eliminated. Remarkable improvement of working efficiency will be thus attained.
REFERENCES:
patent: 4962584 (1990-10-01), Matsuda
patent: 5320013 (1994-06-01), Nonami
patent: 850954 (1952-09-01), None
patent: 674514 (1952-06-01), None
patent: 8-55319 (1996-02-01), None
Crane Daniel C.
Mitsumi Electric Co., Inc.
Whitham Curtis & Christofferson, P.C.
LandOfFree
Method of adjusting height of magnetic head does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of adjusting height of magnetic head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of adjusting height of magnetic head will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2838291