Note: Descriptions are shown in the official language in which they were submitted.
~;~36~
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a magnetic transducer head
and more particularly to such a head formed of composite
magnetic material, viz. the ferromagnetic oxide material
and the ferromagnetic metal material.
2. Description of the Invention
With increase in recording density on magnetic tapes
used as recording media fox video tape recorders (VTRs)l
magnetic tapes having a high residual flux density By and
a high coercive force Ha, for example metal magnetic tape,
in which metal magnetic powder is coated on a non-magnetic
substrate with a binder to form a magnetic recording layer,
are being used in increasing numbers. When the magnetic
transducer head is to be used with the metal tape, the mug-
netic field strength of the magnetic gap of the head must
be elevated in order to cope with the high coercive force
of the tape. It is also necessary to reduce the track width
of the magnetic transducer head with increase in recording
density.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 and 2 are perspective views showing two examples
of the conventional magnetic transducer heads.
Fig. 3 is a plan view showing to an enlarged scale the
tape contacting surface of a conventional magnetic head.
Fig. PA is a SUM photograph showing a crystalline
structure of the two-layered Soundest film formed by sputter-
in on a planar ferrite substrate surface.
,~' .
39~
Fig 4B is a sketch showing only the outstanding feature
of the SUM photograph of Fig. PA.
Fig. PA is an SUM photograph showing a crystalline
structure of the Soundest film formed by sputtering on an
irregular ferrite substrate surface.
Fig. 5B is a sketch showing only the outstanding lea-
lures of the SUM photograph of Fig. PA.
Figs. 6 to 10 are schematic sectional views showing
the manufacture process of the conventional magnetic trays-
dicer head and particularly the orientation of the columnar
crystal growths of, for example, the Soundest film formed on
projecting ferrite portions.
Figs. 11 and 12 are enlarged plan views showing contact
surfaces with the tape of the conventional magnetic trays-
dicer heads.
Fig. 13 is an enlarged plan view showing the contact
surface with the tape of a further conventional magnetic
transducer head.
Fig. 14 is a perspective view showing a magnetic trays-
dicer head according to an embodiment of the present invent-
ion.
Fig 15 is an enlarged plan view showing the contact
surface with the tape of the magnetic transducer head shown
in Fig. 14.
Fig. 16 is an exploded perspective view of the head
shown in Fig. 14, with the explosion being on the core
separation plane.
Figs. 17 Jo 23 are perspective views showing the Seiko
Jo
entail steps for fabrication of the magnetic transducer head
shown in Fig. 19.
Figs 24 and 25 are schematic sectional views showing
the orientation of the columnar crystal growth of the ferry-
magnetic metal film (Phallus alloys film) formed on the
substrate at the process steps shown in Figs. 20 and 21,
respectively.
Fig. I is a perspective view showing a modified groove
profile for the step shown in Fig. 17.
Fig. 27 is an enlarged plan view of the contact surface
with the tape of the magnetic transducer head when the groove
profile as shown in Fig. 26 is employed.
Figs. 28 to 30 are enlarged plan views of the contact
surface with the tape of the magnetic transducer head accord
ding to the modification shown in Fig. 26.
Fig. 31 is a perspective view of a magnetic transducer
head according to a modification.
Fig. 32 is an enlarged plan view showing the contact
surface with the tape of the magnetic transducer head shown
in Fig I
Figs. 33 to 39 are perspective views showing the Seiko-
entail steps for the manufacture of the magnetic transducer
head shown in Fig. 31.
Figs. 40 and 41 are schematic sectional views showing
the orientation of the columnar crystal growth of the ferry-
magnetic metal film (Phallus alloys film) formed on the
substrate at the process steps shown in Fig-. 36 and 37,
respectively.
-- 3 --
~%~
Figs. 42 to 48 are perspective views showing the Seiko-
entail steps for the manufacture of a magnetic transducer
head according to a further modification.
Fig. 49 is a perspective view showing a magnetic trays-
dicer head manufactured by the process steps shown in Figs.
42 to 48, respectively.
There are known various magnetic transducer heads
designed to meet these demands, such as the magnetic
transducer head with the narrow track width shown in
Fig. 1. The major portion of the magnetic transducer head
shown in Fig. 1 is formed of glass or the like nonmagnetic
materials lay lo, and a ferromagnetic metal thin film 2
having a thickness equal to the track width is sandwiched
between these nonmagnetic materials centrally of-the magnet
tic head. This film 2 is prepared by forming a high Perle
ability alloy such as Sends phallus alloys) on the non-
magnetic material lo in the form of a core half by physical
vapor deposition,- such as sputtering. While the track width
can be reduced in this manner, the path of magnetic flux is
defined only by the metal thin film 2 and hence the operate
tonal efficiency is lowered by reason of increased magnetic
reluctance. The metal thin film 2 needs to be formed to a
film thickness equal to the track width by the physical
vapor deposition such as sputtering. Hence the preparation
on the magnetic head is considerably time-consuming in view
of the low deposition rate achievable with the physical
vapor deposition. Since the film 2 needs to be formed on
a large area the number of items that can be dealt with
by a sputtering unit is necessarily limited so that the
-- 4
~23~
heads cannot be mass-produced efficiently. The metal films
2 of extremely small film thicknesses are placed in contact
with each other for formation of the magnetic gap of the
magnetic transducer head, with the result that accuracy in
the gap size and hence the operational reliability are
lowered.
The magnetic transducer head shown in Fig. 2 is proper-
Ed in such a manner that, for increasing the magnetic field
strength of the magnetic gap, ferromagnetic metal thin films
4 such as Soundest are formed on the magnetic gap forming
surfaces of the core halves of ferromagnetic oxides by using
a physical vapor deposition, such as sputtering, and the
core halves are bonded together by the glass 5. Although
the magnetic reluctance of the magnetic transducer head of
Fig. 2 formed of the composite magnetic material can be-made
lower than in the case of the transducer head shown in Fig.
1, the films 4 are formed in a direction normal to the path
of magnetic flux so that the playback output is lowered
because of eddy current loss. Additional gaps may also be
formed between the ferromagnetic oxide cores 3 and metal
magnetic-films 4 thus detracting from the operational retie-
ability of the transducer head.
Also known is a magnetic transducer head formed of
composite magnetic material and having its magnetic gap
forming surface inclined with respect to its surface forming
the ferromagnetic metal film. For example, Fig. 3 shows in
plan view the contact surface with the magnetic tape of the
magnetic transducer head described in a Japanese Patent
.,, - 5
Wreck No. 155513/1983.
The magnetic transducer head shown in Fig, 3 is comprise-
Ed of core halves or core elements 150, 151 formed of ferry-
magnetic oxides, such as Mn-Zn ferrite. Ferromagnetic metal
thin films 155, 156 such as Soundest are deposited on both
sides of and astride ferrite portions 153, 154 projecting
towards a surface forming the magnetic gap 152. The numeral
157 designates a reinforcing glass material. The magnetic
gap of the head is formed by the thin films 155, 156 of a
ferromagnetic metal material deposited in the neighborhood
of the tip ends of the projecting ferrite portions 153, 154.
With these films 155, 156 of the ferromagnetic metal material,
the growth direction of the columnar grain structure at the
tip ends of the projecting ferrite portions 153, 154 is
different from that at both inclined sides thereof, in such
a manner that the crystals grow on both sides in parallel
and uniformly with a constant angle relative to said sides
whereas the crystals growths at the tip ends are in a fan
shape that is, the crystals are spread apart towards their
distal ends. The result is that magnetic permeability of
the ferromagnetic thin films 155, 156 formed on the tip ends
is lowered with resultingly lowered recording characteristics
and playback output of the magnetic head.
It would be worthwhile to consider here as to know the
surface conditions of e.g. the ferrite substrate surface
affect the film forming process when the ferromagnetic metal
thin film is formed by physical vapor deposition on the
ferrite substrate.
''
--6
2~2
In general, a thin magnetic film to be formed by a
physical vapor deposition process is affected in known
manner by the under-layer conditions. Besides the crystal
structure of the substrate and of the under-layer film
formed as an extremely thin under-layer on the substrate,
also noteworthy are the geometrical configuration and unit
format of the substrate surface.
Fig. PA is a photograph taken with a scanning electron-
microscope (SUM) of a two-layered Soundest film formed ho
sputtering on the ferrite substrate with a Sue film 500 A
thick between the Soundest layers. This figure shows, along
with another SUM photograph of Fig. PA, the effect of the
ferrite substrate surface configurations on the film format-
ion. Figs. 4B and 5B are sketches showing only the main
features-appearing in tune photographs of Figs. PA and I
respectively.
Fig. PA shows the Soundest film formed on a planar for-
rite substrate surface. As seen from this photograph, Son-
dust film surfaces AYE, 159B formed on the planar surface
are uniform and the growth of the columnar grain structure
of the crystals appearing in sections AYE, 160B of the
Soundest film is uniform and extends parallel to the thick-
news of the film. In this photograph, the broken section
is taken not only of the Soundest film but of the ferrite
substrate and the broken section is viewed with the scanning
I 2
electron-microsc~pe from an oblique direction. On the
section of the ferrite substrate 161 is seen the section
AYE of the first Soundest layer followed by the section
160B of the second Soundest layer. The film surfaces AYE,
159B belong to the first and second Soundest layers, respect
lively. The thin lines appearing on the surface 159B of
the second Soundest layer represent micro line imperfections
on the polished surface of the ferrite slice propagated to
the Soundest film and do not affect the magnetic permeability
of the film. The photograph is shown in a topsy-turvy state,
that is, with the upper side down and vice verse.
Fig. PA shows the Soundest film formed on an irregular
surface of the ferrite substrate. The photograph shows the
irregular surface 162 of the Soundest film corresponding to
the original irregular surface ferrite substrate. This is
indicative of the competitive growth of the crystal grains
that is not observed when the crystals are allowed to grow
on a smooth planar surface. Also the direction of the co-
lunar crystal growths are not parallel, as may be seen in
a section 163 of the Soundest film, but the columnar crystal
growths are spread apart in a fan shape on the protuberant
portions of the ferrite substrate. In the present SUM photo-
graph, the broken section is waken not only of the Soundest
film but of the ferrite substrate and the viewing direction
is from the oblique upper side. A Soundest film section 163
8 --
~23~2
is seen above a ferrite substrate section 164. A boundary
line AYE between the sections 163, 164 represents a pretty-
Burnett portion on the ferrite substrate surface.
The Soundest film formed on the ferrite substrate having
recesses and protuberances present the direction of columnar
crystal growths different with the inclination of the
recesses. Thus the direction and size of the columnar cry-
slats are different with the profile and inclination ox the
bottom of the substrate recess. The Snidest film surface --
162 is also disturbed and the crystal structure of the film
differs markedly with different inclination on the bottom
of the recess. Such difference in the crystal grain struck
lure accounts for a great difference in the magnetic permea-
ability of the Soundest film. The photograph in this figure
is again-taken in a topsy~turvy position.
It should-be noted that, because magnetic permeability
as well as an isotropic properties (the direction of easy
magnetization) of a ferromagnetic film depends notably on
the film structure, it is desirable that the magnetic film
that makes up a magnetic transducer head, especially one
used for magnetic recording and reproduction, be uniform
in structure. For instance, it is required that columnar
crystals of the aforementioned Soundest film should grow
uniformly and in one direction. Should the orientation so
crystal growth not be uniform in a magnetic film, a certain
~23~
portion of the film exhibits proper magnetic properties
while the remaining portion thereof exhibits inferior
magnetic properties (effect of an isotropy
In Fig. 6, there is schematically shown the structure
of a Soundest film, that is, the orientation of the columnar
crystal growths, when the Soundest film is deposited as by
sputtering on and astride the projecting portion of the
ferrite substrate shown in Fig. 3. It is seen from Fig. 6
that columnar crystals of the Soundest film 171 grow uniform-
lye and parallel to each other on both sides AYE of the pro-
jetting portion 170 but are spread apart from each other
towards the distal ends at a tip end 170B. When the Soundest
film 171 deposited on the tip end 170B is ground for forming
a magnetic gap surface 172, the film structure at or near
the gap surface 172 is different from that on the sides AYE.
Thus, with thy magnetic transducer head of the composite
magnetic material making use of the Soundest film 171 deposit-
Ed on the projecting portion 170, when the Soundest film 171
on the sides AYE exhibits higher magnetic permeability in
the direction of the path of magnetic flux, the film 171
near the tip end 170B exhibits only poor magnetic permeabi-
lily.
Instead of depositing, for instance, a Soundest film on
and astride the projecting portion of the ferrite substrate,
it is also feasible to deposit the Soundest film 177 only on
-- lo --
one side of the projecting portion 175, as by sputtering,
with a masking plate 176 placed to cover the other side of
the projecting portion 175. However, the masking plate 176
gives rise to a shadowing effect because a plate thickness
in excess of several tens of microns is required in cons-
donation of handling and mask-alignment and by reason of
molding constraints. As a result of the shadowing effect,
the film structure of the Soundest film 177 formed in the
vicinity of the tip end 175B of the projecting portion 175B.
and hence magnetic permeability characteristics are differ
rent from those of the film structure on the side AYE.
Thus, when the Soundest film 177 deposited on the tip end
175B is ground to a magnetic gap surface 178 OX the magnetic
transducer head, it is not possible with this magnetic head
to provide both the film portion on the tip end 175B and
the film portion on the side AYE with high magnetic Perle-
ability along the path of magnetic flux.
It is also feasible to get the gap surface ground fur-
then so as to render the film structure at the tip end 175B
of the Soundest film identical with that at the side AYE.
However, in this case, the ferrite portion is exposed on
the magnetic gap surface 179 of the magnetic head, with the
resulting inconvenience that a sufficient magnetic recording
cannot be obtained on the track portions of the high coercive
force magnetic tape, such as metal tape, corresponding to
-- 11 --
2~2
the width of the exposed ferrite portion.
Figs. 11 and 12 show in plan views two further examples
of the contact surface with the tape of the prior-art magnet
tic heads, with the magnetic gap portion being shown to an
enlarged scale. With the magnetic head shown in Fig. 11,
the Soundest films 183 for example are provided only on both
sides of the ferrite portions projecting towards the planar
surface 180 forming the gap and the ferrite portion it ox-
posed on the planar surface 180 forming the gap. The numeral
184 designates a reinforcing glass packing material. This
magnetic transducer head makes use of the Soundest film 183
formed on the planar surface and hence does not surfer from
the above described non-uniform film structure. However,
the magnetic recording on a high coercive force magnetic
tape is insufficient by a width of the ferrite portion ox-
posed on the magnetic gap surface, and the magnetic record-
in characteristics and playback output is correspondingly
lowered.
In the magnetic transducer head shown in Fig. 12, a
Sundays film 187, for example, is formed on ferrite portions
and non-magnetic glass having high melting point portions
188 of core elements 185, 186, so that the head is formed
of composite magnetic material, viz. ferrite and Soundest.
The numeral 190 designates a glass 190 having melting point
lower than that of glass 188. The magnetic gap 189 of the
- 12 -
magnetic transducer head is formed by the portions of the
Soundest film AYE running parallel to the path of magnetic
flux so that the Soundest film AYE in the vicinity of the
magnetic gap 189 is of a uniform film structure. However, the
Soundest film portion 187B corresponding to the bend or knee of
the Soundest film 187 and thus extending over two planar sun-
faces is not of uniform film structure, so that Soundest film
187 as a whole is not constant in magnetic permeability. Also,
in this magnetic transducer head, the Soundest film portion AYE
needs to be of a film thickness corresponding to the track
width. Because of the slow deposition rate of the film posse-
bye with the physical vapor deposition, the process of fabric
cation of the magnetic transducer head is time-consuming.
The Japanese Patent Cook No. 169214/1981 shows a magnet
tic transducer head in which, as shown in Fig. 13, junction
surface 195, 1~96 of magnetic alloy films 191, 192 and ferrite
portions 193, 194 are at an acute angle with respect to
the confronting surfaces of the head gap 197 or to a direct
lion normal to the relative running direction of the magnet
tic recording medium. However, with the magnetic transducer
head shown in Fig. 13, the magnetic alloy films 191, 192
are mounted in opposition to each other in other portions
than the head gap 197 so what a crosstalk may be caused
especially in the longer wavelength signal by picking up
the signals of neighboring tracks or the signals of every
I Jo 13 -
I,
I
other track and a means for avoiding this effectively has
not been found to date. In addition, local wear may be
caused by the head gap 197 offset to one side edge of the
head chip. The magnetic alloy films 191, 192 abut on each
other in such a manner that the direction of columnar cry-
tat growths of the film 191 does not coincide with that of
the film 192 and uniform magnetic properties are difficult
to achieve with the head gap 197.
Although the crystalline Soundest film has been given
hereinabove as an example of a thin ferromagnetic film, a
uniform film structure is also required when an amorphous
alloy is used for forming the thin film. Since the film
it amorphous, it is not the uniformity in the crystal grain
structure but the uniformity in magnetic an isotropy that
matters. If the amorphous alloy is deposited on a planar
surface for forming a thin film, magnetic an isotropy is
identical throughout the film. However, when the alloy is
deposited astride a projecting portion and a planar portion,
the magnetic domain structure or the magnetic permeability
is not uniform.
SUMMARY OF THE INVENTION
In view of the above described prior art devices, it
is a primary object of the present invention to provide a
magnetic transducer head which may be advantageously mass-
produced and which is suitable for high density recording
- 14 -
~3~2~
on a magnetic tape exhibiting a higher coercive force Ha,
such as metal tape.
It is also an object of the present invention to pro-
vise a high output magnetic transducer head which is retie-
bye in operation and exhibits uniform film characteristics
of the thin ferromagnetic metal film in the neighborhood
of the magnetic gap.
It is a further object of the present invention to
provide a magnetic transducer head free of local wear and
exhibiting superior wear resistance.
According to an aspect of the present invention, there
is provided a magnetic transducer head comprising;
a first magnetic core element, and a second magnetic core
element,
each of said first and second core elements comprising a
magnetic ferrite block and a magnetic metal thin film in-
tegrated with said magnetic ferrite block,
said core element having a first planar surface Andy second
planar surface,
said magnetic metal thin film being provided on said second
planar surface and having an edge thereof facing to said
first planar surface, said second planar surface being slant
try provided with respect to said first planar surface,
said fist and second core element being bonded together
to form an operating magnetic gap between said edge of said
' Jo - 15 -
~23~ 2
magnetic metal thin film on said first core element and said
edge of said magnetic metal thin film on said second core
element,
and to form said magnetic metal thin film on said first core
element and said magnetic thin film on said second core
element in one common plane.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, several preferred embodiments
of the preset invention are explained in detail.
Referring first to Fig. 14, a magnetic transducer head
according to the first embodiment of the present invention
is explained, in which a ferromagnetic metal thin film is
formed continuously Eros the front side or the front gap
forming surface to the back side or the back gap forming
surface of the magnetic transducer head.
This head is composed of core elements 80, 81 formed
of ferromagnetic oxides, such as Mn-Zn ferrite. On the
junction surfaces of the core elements 80, 81, there are
formed metal thin films 82 of ferromagnetic metal or high
permeability metal alloy, such as Phallus alloys, by using
the physical vapor deposition, such as sputtering. These
films 82 are continuously formed from the front gap forming
surface to the rear gap forming surface. magnetic gap g
is formed only by these thin films 82. These films 82 on
the core elements 80, 81 Extend as an oblique straight line
when viewed on the tape contact surface, if the small thick-
- 16 -
news of these films 82 is disregarded. The numerals 83, I
designate reinforcing nonmagnetic sections filled in cutout
portions adjacent to the junction surface and also used for
setting a track width Two The numeral 85 designates an
2~2
opening for coils.
The metal thin films 82 are formed on a sole planar
surface defined by one inclined surface AYE of the core
element 80 and one inclined surface AYE of the core element
81. Therefore, the metal thin films 82 are of uniform film
structure in their entirety and exhibit a high magnetic per-
mobility in the direction of the path of magnetic flux for
improving the recording characteristics and increasing play-
back output of the magnetic transducer head.
The surface of forming the thin films 82 forms an acute
angle with the surface of forming the magnetic gap g, as
shown in Fig. 15 showing the contact surface with the magnetic
tape in a plan view. In the present embodiment, the angle
is selected to a relatively small value of approximately
45 so that the interaction of the magnetic gap g with the
interface between the inclined surfaces AYE, AYE and -the thin
films 82 is negligible.
The deposited metal thin films 82 need only to be of a
film thickness t such that
t = Two sin
wherein Two represents a track width and represents
an angle between the surface of forming the metal -thin film
and the surface of forming the magnetic gap. The result is
that the film need not to be deposited to a thickness equal
to the track width and hence the time required for -the pro-
- 18 -
~3~2~2
parathion of the magnetic transducer head may be notably
reduced.
It should be noted that the angle e of 45 between the
surface of forming the films 82 and the surface of forming
the magnetic gap g is not limitative and may also be in the
range from about 20 to about 80. However, the angle more
than 30 is preferred because crosstalk with the neighboring
track is increased with the angle e less than 20. The angle
e less than about 80 is preferred because wear resistance
is lowered with the angle equal to 90. The angle e equal
to 90 also is not preferred because the thickness of the
thin films 82 of the ferromagnetic metal need to be equal
to the track width which gives rise to the nonuniform film
structure and the time-consuming operation in forming the
thin film in vacuum, as described hereinabove.
The metal thin films 82 may be formed of the ferry-
magnetic metals including Phallus alloys, Fe-Al alloys,
Phase alloys, Physique alloys, Nephew alloys (so-called
permalloys) ferromagnetic amorphous metal alloys, or so-
called amorphous alloys, such as metal-metalloid amorphous
alloys, e.g. an alloy of one or more elements selected from
the group of Fe, No and Co with one or more elements select-
Ed from the group of P, C, B and Six or an alloy consisting
essentially of the firstly mentioned alloy and containing
A, Go, Be, Sun, In, Mow W, Tip My, Or, Or, Hi, or Nub, or a
- 19 -
I
metal-metal amorphous alloy consisting essentially of tray-
session metal elements and glass forming metal elements such
as Hi or Or.
Preferably, the composition of the Phallus alloys is
so selected the Al contents are in the range from 2 to 10
weight percent, and the So contents are in the range from
4 to 15 weight percent, the balance being Fe. Thus it is
preferred that, when the Phallus alloys are expressed as
Fe a Al b So c
Where, a, b, and c represent the weight ratio of the
respective associated components, the values of a, b and
c are in the range such that
70 I- a - 95
2 b _ 10
- 4 c _ 15
If the Al or So contents are too low or too high, mug-
netic properties of the Phallus alloys are lowered.
In the above composition, a part of Fe may be replaced
by at least one of Co and Nix
The saturation magnetic flux density may be improved
by replacing a part of Fe with Co. Above all, the maximum
saturation magnetic flux density By may be achieved when 40
weight percent of Fe is replaced by Co. Preferably, the
amount of Co is 0 to 60 weight percent relative to Fe.
On the other hand, by replacing a part of Fe with Nix
- 20 -
~236~
magnetic permeability may be maintained at a higher value
without lowering the saturation magnetic flux density so.
In this case, the amount of No is preferably in the range
from 0 -to 40 weight percent relative to Fe.
Other elements may also be added to the Phallus alloys
for improving its corrosion and wear resistance. The eye-
mints that may be used as such additives may include IIIa
group elements including lanthanides such as So, Y, La, Cue,
No and Go, Ivy group elements such as Tip Or or Hi, Via groups
such as V, Nub or Tax Via group elements such as Or, My or
W; Viva group elements such as My, To or Rev It group eye-
mints such as Cut A or A elements of the platinum group
such as Rut Rho Pod, and Gay In, Go, Sun, Sub or Bit
As film forming process, any known physical vapor depot
session may be employed, such as flash evaporation, ion plats
in, sputtering or cluster ion beam process.
It is known that, in producing the above described thin
film of a ferromagnetic metal by, for example, sputtering,
a columnar structure is induced in a thin film of a ferry-
magnetic metal obtained under a certain condition and thus
a thin film with excellent magnetic properties may be obtain
nod. Above all, when -the thin film of -the ferromagnetic
metal is designed to be used as the composite magnetic head,
it is generally thought that, for suppressing the an isotropy
of the formed film, it would be more preferred to induce the
- 21 -
I
growth of the columnar structure at right angles with the
substrate surface on which the film is formed.
However, with the ferromagnetic metal thin film obtain-
Ed in this manner, that is, with the columnar structure
caused to grow at right angles with the substrate surface,
the slightest changes in sputtering conditions or substrate
position delicately affect the growth of the columnar struck
lure so that the resulting thin film is changed vitally in
magnetic permeability with resulting dispersion in the play-
back output of the magnetic transducer head.
It is therefore preferred that the metal thin films 82
ye deposited in such a manner that the direction of the
columnar crystal growths be inclined at a predetermined angle
of 5 to 45 with respect to a normal line drawn to each
of the inclined planar surfaces AYE, AYE.
When the metal thin films 82 are caused to grow in -this
manner at a predetermined angle with respect to the normal
lines drawn to -the inclined surfaces AYE, AYE magnetic pro-
parties of the resulting ferromagnetic metal thin films 82
are stable and superior resulting in improved magnetic pro-
parties of the magnetic transducer head.
The angle the direction of the columnar crystal growths
of the metal thin films 82 makes with the normal direction
to the inclined surfaces AYE, AYE is preferably in -the range
of 5 -to 45 for best results.
- 22 -
When the angle is less than 5, the playback output
of the magnetic transducer head is greatly fluctuated thus
resulting in a lower yield rate and elevated costs. When
the angle is more than 45, magnetic properties of -the
thin films 82 are drastically affected by considerable de-
pletion between the columnar crystals and surface rugged-
news thus causing the playback output of the magnetic trays-
dicer head to be lowered. With the angle in the range
from 5 to 45, the growth of the columnar crystals is fixed
because of the oblique incidence, and the magnetic proper-
ties are not changed markedly with small fluctuations in the
sputtering conditions or difference in the substrate posit-
ion. The alternating condensation and rare faction between
or within the columnar crystals induced by oblique growths
disperse-the strain caused during sputtering, film annealing
and the working of the head so that the playback output is
increased while the output fluctuations are less than about
2 dub.
As a means of regulating the direction of growth of the
ferromagnetic metal thin film 82, the substrate surface may
be inclined with respect to an evaporation source, or the
substrate may be placed around the evaporation source so
that vaporized magnetic particles coming from an oblique
direction may be deposited on -the substrate.
AlthoucJh the metal thin film 82 is formed as single
- 23 -
layer by the above described physical vapor deposition, a
plurality of thin metal layers may be also be formed with
an electrically insulating film or films such as Sue, Tao,
AYE, ZrO2 or Sweeney between the adjacent thin metal layer
or layers. Any desired number of the ferromagnetic metal
layers may be used for the formation of the metal thin film.
Since the magnetic gap g is formed only by the metal
thin films 82 endowed with Hayakawa magnetic permeability, the
magnetic transducer head has a high recording characters-
tics and playback output compatible with the magnetic tape
exhibiting high coercive force Ha, such as metal tape.
Since the metal thin films 82 are formed on a common
planar surface such as inclined surface AYE of the project-
in portion of the core element 80 or inclined surface AYE
of the projecting portion, the film structure of the metal
thin film 82 (Phallus alloys film), viz. the orientation
of the columnar crystal growths is uniform and parallel no-t
only in the neighborhood of the magnetic gap g but on the
overall surface of the inclined sides AYE, AYE. The result
is that the metal thin film 82 shows high magnetic permeabi-
lily in its entirety along the path of magnetic flux for
improving the recording characteristics and increasing play-
back output of the magnetic transducer head.
The contact surface with -the tape of the magnetic trays-
dicer head is substantially formed of ferromagnetic oxides,
- 24 -
~æ~ æ
wear resistance of the head is also improved.
In distinction from the conventional practice according
to which ferromagnetic metal foils are manually applied with
the aid of glass, organic adhesives or inorganic adhesives,
the metal thin films 82 are provided by physical vapor depot
session so that the films are more homogeneous and the operate
tonal reliability of the transducer head is also improved.
According to the present invention, track widths in the
range from several to several tens of microns can be formed
easily and a narrow track may be provided to -the head by
reducing the number of layers or film thickness of the metal
thin film 82.
The magnetic transducer head described hereinabove may
be used advantageously for high density recording on a mug-
netic tape with high coercive force Ha by virtue of the high
magnetic field strength of the magnetic gap g and the en Han-
god playback output.
For clarifying the structure of -the magnetic transducer
head of the present embodiment, the manufacture process
thereof will be explained below by referring to Figs. 17 to
23,
In preparing -the magnetic transducer head of the present
embodiment, a plurality of vie grooves 91 are transversely
formed on the upper surface of a substrate 90 of ferromagne-
tic oxides, such as Mn-Zn ferrite, with the aid of a revolve
- 25 -
6~2
ivy grindstone (Fig. 17).
These grooves 91 may also be polygonal in cross-section
and the inner wall surface of these grooves 91 may be bent
in two or more steps for enlarging the distance between the
ferromagnetic oxides and the ferromagnetic metal thin film.
With such groove profile, high-output magnetic transducer
heads with less crosstalk may be obtained in -the longer wave-
length range while maintaining a large junction area between
the ferromagnetic oxide on one core half and the ferromagne-
tic metal thin film on another core half.
The profile of the groove 91 as shown in Fig. 26 may
be used as an example. The contact surface with the tape
of the resulting magnetic head is as shown in Fig. 27 where-
in end faces 80s, 81s of the track width regulating grooves
of the core elements 80, 81 are bent in two steps so as to
be in register with the profile of the groove 91, that is,
with a portion of the inner wall surface of a polygon.
Therefore, some distance between the end faces 80B, 81B
of the track width regulating grooves and the ferromagnetic
metal thin films 82 may be procured and the crosstalk combo-
newts resulting from reproduction of the long wavelength
components may be lowered.
In addition, the end face portions blue, 80B2 or 81s1,
81s2 that make up the end faces SOB, 81B of the track width
regulating grooves are inclined at different angles from
- 26 -
the azimuth angle of the magnetic gap g, so that crosstalk
with adjacent and adjacent hut one tracks is lowered.
In general, means are employed to lower the crosstalk
between the adjacent tracks to a negligible level, for ins-
lance, recording the neighboring tracks with different
azimuth angles for removing the effect of crosstalk (mange-
tic tape in VTR). However, the crosstalk is caused between
every other track having the same azimuth angle. no the
present embodiment, the end faces 80B, 81B of the track
width regulating grooves of the core elements 80, 81 are
inclined in two steps at different angles from the azimuth
angle of the magnetic gap g so that, even when the edges
of the end face portions 80B1, 80B2, blue, 81B2 of the core
elements 80, 81 are in register with every neighboring track
or every-other track, signal pickup from every neighboring
track or every other track or crosstalk may be lowered by
azimuth loss.
Figs. 28, 29 and 30 show in plan views the contact
surface with the tape according to modified embodiments
wherein the groove 91 is changed in profile. In these
modifications, end faces 80B, 81B of the -track width regular
tying grooves on both sides of the magnetic gap g are change
Ed in profile. In the embodiment shown in Ego. 28, the end
faces 80B, 81B of the track width regulating grooves framed
on core elements 80, 81 are formed as gently sloped surfaces
- 27 -
~æ3~2~
with knees blue, 80B2, 81B1, 81B2. In the embodiment shown
in Fig. 29, the end faces 80B, 81B of the track width rug-
feting grooves on the core elements 80, 81 are formed as
surfaces with knees blue, 80B2, blue, 81B2 with larger radii
of curvature at the knees. In the embodiment shown in Fig.
30, the end faces 80B, 81B of the track width regulating
grooves on the core elements 80, 81 are formed as surfaces
with double knees blue, 80B2, 80B3, blue, 81B2, 81B3-
The end faces of the track width regulating grooves may also be modified in such a manner that the inclined
surface with a knee has different tilts in the respective
segments divided by the knee, or the inclined surface has
more than three knees.
. Next, glass having high melting point 92 is filled in
a molten-state in the grooves 91, after which the substrate
surface is ground smooth (Fig. 18~.
Next, a plurality of vie grooves 93 are formed so as
-to be adjacent to and not to overlap with the aforementioned
vie grooves 91. The inner wall surface of each groove 93
makes an angle of e.g. 45 with respect to the upper subs-
rate surface (Fig. 19).
Then a ferromagnetic alloy, such as Phallus alloys,
is deposited on the upper surface of the substrate 90 by
any known physical vapor deposition such as sputtering, ion
plating or vacuum evaporation, thereby forming a metal thin
- 28 -
~236~
film 94 in the vie grooves 93 (Fig. 20).
Then the upper and front surfaces of the substrate 90
are ground smooth and removing the metal thin film on the
surface of the substrate. (Fig. 21)
For forming the core element on the winding groove side,
a groove 95 for coils in the resulting magnetic transducer
head and a glass filling groove 96 are cut on the thus pro-
cussed substrate 90 (Fig. 21) for providing a substrate 97
formed of ferromagnetic oxide (Fig. 22).
The substrates 90 and 97 are then stacked together by
placing a gap spacer there between and with the respective
planar surfaces provided with the metal thin films 94 lag-
in to each other. Low melting glass rods are inserted in-to
the groove for coils 95 and the glass filling groove 96 for
melt-bonding -the substrates together into one block 98.
At this time, glass having low melting point 99 is elude
into the remaining grooves on the metal thin films 94 of
the substrates 90, 97 (Fig. 23).
The block 98 is then cut along lines b-b and by for
providing a plurality of head chips.
The contact surface of each head chip with the magnetic
tape is then ground to a cylindrical profile for producing
the magnetic transducer head shown in Fig. 14. This mug-
netic transducer head has its core element 80 derived from
substrate 90 and another core element 81 derived from sub-
_ I _
I
striate 90 and another core element 81 derived from substrate. The metal thin film 82 corresponds to the metal thin
film 94, the non-magnetic filling material 83 to the lass
having high melting point 92 and the non-magnetic filling
material to the glass having lower melting point 99.
The opening for coils 85 corresponds to the groove for coils
95.
In Figs. 24 and 25, sections through the substrate 90
are taken at the steps shown in Figs. 20 and 21, respect-
very, for illustrating the film structure of the metal thin
film 94 IFe-Al-Si alloys film) or the orientation of the
columnar crystal growths. us shown in these figures, a non-
uniform film structure portion R is ground off during the
gap surface grinding step shown in Fig. 21 so that only the
metal thin film 94 having uniform film structure is left
on the inclined surface of the groove 93. The result is
that the magnetic transducer head having a high and stable
output may be obtained because each portion of the metal
thin film 82 formed on the common planar surface may have
a high permeability along the path of magnetic flux.
A modified embodiment in which the ferromagnetic metal
thin film is formed only in the vicinity of the magnetic
gap is hereafter explained.
Fig. 31 shows in perspective the magnetic transducer
head according to the present modification. The magnetic
- 30 -
I
transducer head is formed of a composite magnetic material
and consists of a pair of core elements 10, 11 of ferry-
magnetic oxides such as Mn-Zn ferrite. In the vicinity of
the magnetic gap g, there are formed metal -thin films AYE,
14B of ferromagnetic metal or high permeability metal alloy,
such as Phallus alloys, by using the physical vapor depot
session, such as sputtering. Non-magnetic packing materials
AYE, 12B and 13 are packed in molten state in the neighbor-
hood of the planar surface of the magnetic gap g.
It should be noted that the planar surface forming -the
metal thin films AYE, 14B and the planar surface forming
the magnetic gap g are inclined to each other at an angle
as shown in Fig. 32 showing the contact surface with the
tape of the magnetic transducer head. In the present embo-
dominate, the angle o is approximately 45.
Since the metal thin films AYE, 14B are formed only
in the vicinity of the magnetic gap g, -the film surface may
be reduced with -the result that the number of unit chips
that can be processed at a time by e.g. sputtering can be
notably increased with improved efficiency in mass product-
ion. With increase in the number of magnetic -transducer
heads that can be produced from a unit film area, manufacture
costs of the magnetic transducer heads may be lowered.
On account of the reduced area of the metal thin films
AYE, 14s on -the core elements 10, 11 of the ferromagnetic
oxides, any strain of the metal thin films AYE, 14B caused
by the difference in the coefficients of thermal expansion
of the core elements and the metal thin films or resulting
break or crack occurrence in the core elements 10, 11 may
be avoided with improved operational efficiency and yield
rate in the manufacture of the magnetic transducer heads.
The metal thin films AYE, 14B of high magnetic permea-
ability defining the magnetic gap g are formed in -the vicini-
try of the magnetic gap g, and the rear side of the head is
formed by ferromagnetic oxides with a large junction surface,
so that the head exhibits an improved performance with lesser
magnetic reluctance and high sensitivity.
Since the magnetic gap g is formed only by the ferry-
magnetic metal thin films AYE, 14B of high magnetic permea-
ability, the head has a high recording characteristics and
playback output compatible with magnetic -capes of high coon-
give force such as metal tape.
The metal -thin film AYE is formed on a planar surface
on the non-magnetic packing material AYE and the side lo
of the projecting portion of the core element 10, while the
metal thin film 14B is formed on a planar surface on the
nonmagnetic packing material 12B and the side lea of -the
projecting portion of -the core element 11. Hence, -the film
structure of the orientation of -the columnar crystal growths
of the metal (Phallus alloys) thin films AYE, 14B is uniform
- 32 -
and parallel both in the neighborhood of the magnetic gap
g and on the sides loan lea. The result is that the metal
thin films AYE, 14B exhibit in their entirety a high magnet
tic permeability in the direction of the path of magnetic
flux so that the recording characteristics and playback out
put of the magnetic transducer head is notably improved.
The rear sides of the magnetic transducer head are
united together with the ferromagnetic oxides such Mn-Zn
ferrite abutting to each other so that a large bonding
strength may be achieved with improved yield rate despite
inferior bonding properties between the metal thin films
AYE, 14B and the core elements 10, 11. There is no risk
that back track deviation be caused during processing, thus
resulting in an improved operational reliability of the
magnetic-transducer head.
Since the majority of the contact surface with the tape
of the magnetic -transducer head is formed of ferromagnetic
oxides, wear resistance of the magnetic transducer head is
also improved.
In distinction from the conventional practice in which
ferromagnetic metal foils are manually bonded one upon the
other with an adhesive layer of glass, organic adhesives
or inorganic adhesives, the metal thin films AYE 14B are
formed by a physical vapor deposition, so that the formed
film is homogeneous for further improving -the operational
- 33 -
I
reliability of the magnetic transducer head.
The track width can be easily selected in a wide range
from several to several tens of microns so that the magnetic
transducer head with a narrow -track width may be obtained
by using a reduced film thickness or a reduced number of
film layers.
As described hereinabove, the magnetic transducer head
of the present embodiment has a high magnetic field strength
of the magnetic gap g and a high playback output, so that
it is superior in operational reliability and productivity
and suitable for high density recording on a magnetic tape
having a high coercive force Ha such as metal tape.
The manufacture process for the magnetic transducer
head shown in Fig. 31 is now explained by referring to Figs.
33 to 39.
On a longitudinal ridge of a substrate 20 of a ferry-
magnetic oxide, such as Mn-Zn ferrite, a plurality of dived-
fat recesses 21 are cut with the aid of a revolving grind-
stone or electrolytic etching fig. 33). The upper side or
surface 23 of the substrate 20 corresponds to the magnetic
gap forming surface and the recess 21 is formed at a port-
ion of the substrate 20 where the magnetic gap is to be
formed. The recess 21 may also be polyhedral and provided
with curved portions, as in the preceding embodiment.
Glass having high melting point is packed in molten
- 34 -
it
state in the recess 21 at AYE and both the upper side 23
and the front side 24 are ground smooth (Fig. 34).
On the same ridge 25 are then formed a second plurality
of dihedral recesses 25 adjacent to said recesses 21 filled
with glass packing AYE and so as to be partially overlapped
with the recess 21 (Fig. 35). A part of the glass packing
AYE is exposed on an inner wall side or facet 26 of the
recess 25. A line of intersection 27 of the wall side 26
and the upper side 23 forms a right angle with the front
side 24, while the inner wall side 26 makes an angle of say
45 with the upper side 23.
Next, a high permeability alloy such as Phallus alloys
is deposited in the neighborhood of the recesses 25 of the
substrate 20 with the intermediary of an insulating film
with the-aid of a physical vapor deposition such as sputter-
in for forming a ferromagnetic metal thin film 28 (Fugue
The substrate 20 is placed at this -time in the sputtering
apparatus at an inclined position for more efficient deposit-
in of the inner wall sides 26.
Then a glass packing 29 having a melting point lower
than that of the glass packing 22 is packed in the molten
state in the recesses 25 provided with the metal thin film
28, after which the upper side 23 and the front side 24 are
ground to a mirror finish (Fig. 37). At this time, a part
of the metal -thin film 28 deposited during the preceding
- 35 -
I
step remains on the wall sides 26 of the recesses 25 so that
the ferromagnetic metal thin films AYE are deposited on the
sides 26.
For forming a winding groove side core element, a groove
31 for coils is formed in the substrate 20 of ferromagnetic
oxides shown in Fig. 32 for providing a substrate 30 of ferry-
magnetic oxides shown in Fig. 38. The recesses 21 of the
substrate shown in Fig. 38 are filled with glass having high
melting point 22B in the molten state, which the inner wall
sides of the recesses 25 are provided with ferromagnetic
metal thin films 23B.
The substrates 20, 30 are stacked and bonded together
with molten glass, with the upper side 23 or the magnetic
gap forming surface of the substrate 20 abutting on the upper
side 32 or the magnetic gap forming surface of the substrate
30 with the medium of a gap spacer (Fig. 39) for providing
a block 33 consisting of the substrates 20 and 30. The block
33 is then sliced along lines a a, aye' for forming a plus
reality of head chips. The gap spacer may be formed of Sue,
ZrO2, Tao or Or, as desired.
The contact surface with the tape of the head chip is
then subjected to cylindrical grinding for forming a magnetic
transducer head as shown in Fig. 31. The core elements 10
and 11 of -the magnetic -transducer head shown in Fig. 31 are
derived from the substrates 20 and 30, respectively. The
- 36 -
I
non-magnetic packing materials AYE, 12B correspond -to the
glass packing materials having high melting point AYE, 22B,
respectively, while the non-magnetic packing material 13
corresponds to the glass packing material having low melt-
in point 13. The ferromagnetic metal thin films AYE, 14B
of the magnetic transducer head correspond to the metal thin
films AYE, 28B, while the opening for coils 15 corresponds
to the groove for coils 31 on the substrate.
In the above described magnetic transducer head, a
portion Q of the metal thin film 28 of the nonuniform film
structure formed during the process step shown in Fig. 36
is removed by the grinding operation of the gap surface, as
schematically shown in Fig. 40, 41 showing the orientation
of columnar crystal growths or film structure of the ferry-
magnetic-metal thin film, for example, the Phallus alloys
film. In this manner, only the metal thin films AYE, 28s
of the uniform structure are left on a sole inclined planar
surface which is the inner wall side of facet 26 of the
recess 25. The result is that each portion of the metal
thin films AYE, 28B exhibits high magnetic permeability
along the path of magnetic flux and the magnetic transducer
head has a high and stable playback output.
In the present embodiment, as described hereinabove,
a second planar surface forming an angle of 20 to 80 with
respect to a first planar surface which later forms the
magnetic gap surface is formed by the grinding process and
in the neighborhood of the first recess 21 filled previously
with glass having high melting point, and -the ferromagnetic
metal thin film 28 is formed by a physical vapor deposition
on said second surface which is inclined with respect to
said first planar surface, which is then ground so that only
the thin film formed on the inclined second planar surface
is left at least in the vicinity of the magnetic gap. The
result is -that the metal thin films AYE, 28B are of uniform
film structure throughout thus providing for a high and
stable output of the magnetic transducer head.
With the above magnetic transducer head, the ferry-
magnetic oxides of the two core elements are melt-bonded
together directly with molten glass on the rear junction
sides or-back gap surfaces of -the head. The result is that
the head chip shown an improved breaking strength and can
be manufactured easily with an improved yield rate.
Referring to Figs. 42 to 48, a further example of -the
magnetic transducer head manufactured by a further process
is explained.
On an upper surface 41 corresponding to -the contact
surface with the tape of the substrate 40 of ferromagnetic
oxides, such as Mn-Zn ferrite, a plurality of grooves 42
having the square shaped section are obliquely formed (Fig.
42). Each groove 42 has a depth to reach the opening for
- 38 -
I
coils provided in the transducer head.
Glass having high melting point is then packed in
molten state at AYE in each groove 42, after which the
upper side 41 and the front side 44 are ground smooth
(Fig. 43).
Then, a second plurality of grooves 45 having the
square shaped section are formed on the upper side 41 in
the reverse oblique direction to the grooves 42 so as to
partially overlap with these grooves 42 filled with glass
having high melting point AYE (Fig. 44). These grooves
45 are approximately equal in depth to the glass-packed
grooves 42. The line of intersection 47 the inner side
46 of the groove 45 makes with the front side 44 is situate
Ed on the sectional plane of the glass AYE exposed on -the
front side 44 and forms a right angle with -the upper side
41. The inner side 46 makes an angle of say 45 with -the
front side 44.
Then, a film of high permeability alloy, such as Fe-
Allis alloys, is formed in the vicinity of the grooves 44
on the substrate 40 by a physical vapor deposition, such
as sputtering, for forming a ferromagnetic metal thin film
48 (Fig. 45~. The substrate 40 is maintained at an inclined
position within the sputtering apparatus for more efficient
forming of the film on the inner side 46.
Then, a glass 49 having lower melting point -than the
- 39 -
I
glass AYE is packed in molten state in the grooves 45 provide
Ed with the metal thin film 48, after which the upper and
front sides 41/ 44 are ground to a mirror finish (Fig. owe
At this time, a part of the metal thin film 48 is left on
the inner sides 46 of the grooves 45 so that the ferromagne-
tic metal thin film AYE is provided on these inner sides 46.
For forming the core element provided with a groove
for coils 61, the groove 61 is formed on the substrate 40
of ferromagnetic oxides as shown in Fig. 46 for producing
the substrate 60 of ferromagnetic oxides as shown in Fig.
47. The grooves 42 of the substrate 60 are packed with
glass having high melting point 43B in molten state, while
the ferromagnetic metal thin films 48B are formed on -the
inner sides 46 of the grooves 45.
The-substrates 40, 60 are then stacked and bonded to-
getter by molten glass with the front side 44 of the sub-
striate 40 which later forms the magnetic gap abutting on
the front side 62 of the substrate 60 which later forms the
gap by the medium of a gap spacer (Fig. 48) for providing
a block 63 consisting of the substrates 40 and 60. The
block 63 is then sliced along lines A-A, AYE' for forming
a plurality of head chips.
The contact surface with the magnetic tape of the head
chip is then subjected to cylindrical processing for forming
a magnetic transducer head shown in Fig. 49. The core
- 40 -
elements 70, 71 of the magnetic transducer head shown in
Fig. 49 are derived from the substrates 40, 60, respectively.
The non-magnetic packing materials AYE, 72B correspond to
the glass materials having high melting point AYE, 43B fill-
Ed in the grooves 4 2, while the non-magnetic packing material
73 corresponds to the glass material having low melting point
49 packed into the grooves 45. The ferromagnetic metal thin
films AYE, 74B formed on the magnetic transducer head cores-
pond to the metal thin films AYE, 48B formed on the inner
sides 46 of the grooves 45, while the opening for coils 75
corresponds to the groove for coils 61.
With the magnetic transducer head of Fig. 49 manufacture
Ed with the above described process, the planar surface form-
in the magnetic gap is inclined at an appropriate angle with
respect to the planar surface of the ferromagnetic metal thin
films AYE, 74B, which are formed only in -the vicinity of the
magnetic gap, thus affording the properties of the magnetic
transducer head comparable to those of the magnetic trounced-
con head shown in Fig. 31.
Since the magnetic gap g is formed only by metal thin
films AYE, 74B, the head is improved in output and compute-
bye with metal tapes.
The metal thin film AYE is formed on a continuous planar
surface consisting of the side AYE of the projecting portion
of the core element 70 and a side of the non-magnetic material
- 41 -
AYE, whereas the metal thin film 74B is formed on a keynote-
Nazi planar surface consisting of the side AYE of the pro-
jetting portion of the core element 71 and a side of the
non-magnetic material 7~B. The result is that the metal
thin films AYE, 74B are of uniform film structure through-
out and exhibit high magnetic permeability in the direction
of the path of magnetic flux so that an improvement is
achieved in the recording characteristics and playback out-
put of the transducer head.
In the preceding embodiment, the lines a-a, aye' along
which the composite block shown in Fig. 39 is sliced are at
right angles with the abutting surfaces of the substrates
20 and 30. It is however possible to slice the block in a
direction other than the right angle for providing a magnetic
'transducer head for azimuth recording. It is also possible
in the present embodiment to slice the block shown in Fig.
48 in an inclined direction with respect -to -the abutting
surfaces of the substrates 40, 60 instead of along lines
A-A, AYE' or at right angles with said abutting surfaces
for similarly producing magnetic transducer heads for azimuth
recording.
With the magnetic transducer head of the present invent-
ion shown in Figs. 14, 31 and 49, grooves formed on the sub-
striate of ferromagnetic oxides are previously packed with
glass and second grooves are formed in the neighborhood of
- 42 -
I
the first grooves for forming inclined planar surfaces on
which to form ferromagnetic metal thin films. The result
is that magnetic properties of the head are uniform not only
in the film portions adjacent to the magnetic gap but in
the film portions on the sides of the projecting substrate
portion and the ferromagnetic oxides are not exposed on the
magnetic gap portion.
When used with high coercive force magnetic tape such
as metal tape, the magnetic transducer head of the present
invention was found to have a playback output higher by
about 3 dub in the frequency range of 1 to 5 MHz as compared
to the experimental values obtained with the conventional
magnetic -transducer head such as shown in Fig. 11 wherein
the ferrite is exposed in the gap portion for a length equal
to erg, 40 percent of the track width. The magnetic trays-
dicer head of the present invention may be manufactured with
lesser diemesional fluctuations than in the case of the con-
ventional magnetic transducer head shown in Fig. 3 and was
found to have a playback output higher about 3 dub than that
of this conventional -transducer head.
The Nissan ferrite, for example, may be used in place
of the Mn-Zn ferrite as the ferromagnetic oxide forming the
core elements. Permalloy or amorphous alloys may be used
in place of Phallus alloys as the high permeability magnetic
material forming the ferromagnetic metal thin film, as
- 43 -
discussed hereinabove.
In using the amorphous alloys, uniform film properties
of the ferromagnetic metal thin film is imparted by magnetic
an isotropy. The metal thin film may have uniform magnetic
properties throughout by forming the thin film on a sole
planar surface in accordance with the present invention.
The ferromagnetic metal thin film may be advantageously
composed of one or more layers within the scope of -the present
invention.
It will be appreciated Eros the foregoing that the mug-
netic transducer head of the present invention is composed
of two core elements formed of ferromagnetic oxides, and
the ferromagnetic metal thin films are deposited by physical
vapor deposition in proximity to -the junction surface of
the core-elements so that the general plane of -these metal
thin films is inclined at an angle with respect to the junk-
lion surface of the core elements which later forms -the mug-
netic gap surface. The magnetic gap is formed solely by the
metal thin films which are formed on a common planar surface.
Hence, when forming the metal thin films, there is no
necessity of providing a film thickness corresponding to
-the track width and the -transducer head may be mass produced
within a shorter time.
The major portion of the contact surface with the tape
is formed of ferromagnetic oxides so that the head has
- 44 -
superior wear resistance.
The magnetic gap is formed only of the metal thin film
so that the head is Hun output and compatible with the
high coercive tape such as metal tape.
The metal thin film is formed on one planar surface
and hence uniform in the film structure throughout, while
the metal thin film as a whole exhibits high magnetic Perle-
ability in the direction of the path of magnetic flux.
Hence, the magnetic transducer head is extremely reliable
in operation and has a high recording characteristics and
playback output.
The magnetic transducer head of the present invention
is so constructed that the magnetic gap is at the center
of the head chip and surrounded on both sides with non-
magnetic-materials for avoiding local wear of the head.
The ferromagnetic metal thin films forming the magnetic
gap is formed on a straight line when seen on the contact
surface with the tape so that the ferromagnetic metal thin
films are not in opposition to each other in other locations
than the magnetic gap. The result is the reduced crosstalk
in the long wavelength range. The crosstalk may be further
lowered by changing the groove profile with respect to the
core elements.
The uniform magnetic proper-ties may be assured by the
unidirectional growth of the columnar structure of the
- 45 -
ferromagnetic metal thin films when seen on the contact
surface with the tape.
- 46 -
