High speed magnetic coil for magneto-optical head

Details High speed magnetic coil for magneto-optical head High speed magnetic coil for magneto-optical head

2000-11-01

2003-03-04

Dinh, Tan (Department: 2653)

Dynamic information storage or retrieval

Storage or retrieval by simultaneous application of diverse...

Magnetic field and light beam

C369S013170

Reexamination Certificate

active

06529448

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a magneto-optical recording apparatus for recording an information signal on a magneto-optical recording medium on which an information signal is recorded by a magnetic field modulation recording method, a magnetic head used for the magneto-optical recording apparatus, and a magnetic head coil used for the magnetic head.
BACKGROUND ART
A conventionally known example of magneto-optical recording apparatuses for recording information signals at high density on a magneto-optical recording medium such as a magneto-optical disk adopts a magnetic field modulation method. The apparatus of this type comprises optical and magnetic heads. The optical head converges a laser beam into a small light spot to irradiate the magnetic recording layer of a magneto-optical recording medium. The magnetic head vertically applies a magnetic field modulated by an information signal to the laser beam irradiated portion of the magneto-optical recording medium, thereby recording the information signal on the magneto-optical recording medium.
This conventional magneto-optical recording apparatus uses a magnetic head having an arrangement as disclosed in, e.g., Japanese Patent Application Laid-open No. 6-309607.
FIG. 9
is a sectional view showing the structure of this conventional magnetic head.
Reference numeral
50
denotes a core made of a magnetic material such as ferrite; and
51
, a coil formed by winding a magnetic wire (thin electric wire prepared by forming an insulating film of polyurethane or the like on a conductive wire made of a conductive material such as copper) on a magnetic pole p
3
of the core. By supplying a current to the coil
51
, a magnetic field is generated from the end face of the magnetic pole p
3
of the core
50
, and vertically applied to a magneto-optical recording medium.
In recent years, demands have arisen for high-speed recording of an information signal. Along with this, the modulation frequency of the magnetic field must be increased. However, when the coil is formed from a magnetic wire, like the conventional magnetic head, the sectional shape and size of a manufacturable conductive wire are limited and cannot be arbitrarily set. If the diameter of the conductive wire forming the magnetic wire is set to 50 &mgr;m or less to downsize the coil, the magnetic wire is difficult to align vertically and horizontally, as shown in
FIG. 9
, so as to constitute the coil. This results in irregular turns of the disordered winding. For this reason, the coil diameter is inevitably large. For a vertically elongated coil shape, as shown in
FIG. 9
, the coil inductance increases so as to decrease the magnetic field generation efficiency of the magnetic head. However, a thin magnetic wire made of a conductive wire 50 &mgr;m or less in diameter is very difficult to manufacture not as a vertically elongated coil but as a flat coil with a low inductance. To increase the modulation frequency of the magnetic field, a high drive voltage proportional to the modulation frequency or coil inductance must be applied to the magnetic head coil, which increases the power consumption of the magneto-optical recording apparatus. In addition, the RF resistance of the coil caused by the skin and proximity effects of the magnetic wire cannot be satisfactorily reduced. The RF loss of the magnetic head increases, heat generated by the magnetic head degrades the magnetic characteristics of the magnetic head, and a magnetic field of a desired strength is difficult to generate. This problem becomes serious at a maximum magnetic field modulation frequency of 8 MHz or more.
DISCLOSURE OF INVENTION
According to the present invention, a flat magnetic head coil constituted by spiral coil patterns made of a conductive material film and two terminals connected to the coil patterns is characterized in that the coil patterns have a substantially rectangular sectional shape, a minimum pitch P [&mgr;m] of the coil pattern, a width W [&mgr;m] of the sectional shape at the minimum pitch P, and a height H [&mgr;m] satisfy inequalities (10) and (11):
15 [&mgr;m]
≦P≦
70 [&mgr;m]  (10)
1.85−0.012
P≦H/W≦
7.5−0.06
P
  (11)
when an impedance Z
0
between the two terminals of the coil while at least a core made of a magnetic material is not attached is regarded to be equivalently constituted by an inductance L
0
, an RF resistance Rp
0
parallel to the inductance L
0
, and a DC resistance Rs which is series-connected to the inductance L
0
and is independent of a frequency, the inductance L
0
[&mgr;H] at 10 MHz satisfies inequality (5):
L
0
≦0.85
[&mgr;H]
  (5)
The magnetic head coil is characterized in that the inductance L
0
[&mgr;H] at 10 MHz, and the RF resistance Rp
0
[&OHgr;] at 20 MHz and the DC resistance Rs [&OHgr;] satisfy inequalities (6) and (8):
Rp
0
≧
L
0
×1500  (6)
Rs≦
2  (8)
The magnetic head coil is characterized in that the inductance L
0
[&mgr;H] at 10 MHz, and the RF resistance Rp
0
[&OHgr;] at 20 MHz satisfy inequality (7):
 
Rp
0
≧L
0
×2000  (7)
The magnetic head coil is characterized in that at least one of the coil patterns is formed on a lower surface side of the magnetic head coil facing a magneto-optical recording medium, and an interval Tb [&mgr;m] between the coil patterns, an interval Tc [&mgr;m] between an end face of the coil pattern formed on the lower surface side and a lower surface of the magnetic head coil, and a thickness T [&mgr;m] of the magnetic head coil satisfy inequalities (13), (14), and (15):
2 [&mgr;m]≦
Tb≦
70 [&mgr;m]  (13)
Tc≦
1.5
H
  (14)
50 [&mgr;m]
≦T≦
450 [&mgr;m]  (15)
The magnetic head coil is characterized in that a total number N of turns of the coil patterns, a minimum radius r
1
[mm] of an innermost periphery of the coil pattern, and a maximum radius r
2
[mm] of an outermost periphery satisfy inequalities (16), (17), and (18):
14≦
N
≦40  (16)
r
1
≦0.2 [mm]  (17)
r
2
≦1.1 [mm]  (18)
According to the present invention, a flat magnetic head coil constituted by spiral coil patterns made of a conductive material film and two terminals connected to the coil patterns is characterized in that a light-transmitting portion is formed at a center of the coil, the coil patterns have a substantially rectangular sectional shape, a minimum pitch P [&mgr;m] of the coil pattern, a width W [&mgr;m] of the sectional shape at the minimum pitch P, and a height H [&mgr;m] satisfy inequalities (29) and (30):
15 [&mgr;m]≦
P
≦50 [&mgr;m]  (29)
1.85−0.012
P≦H/W
≦7.5−0.06
P
  (30)
when an impedance Z
0
between the two terminals of the coil while at least a core made of a magnetic material is not attached is regarded to be equivalently constituted by an inductance L
0
, an RF resistance Rp
0
parallel to the inductance L
0
, and a DC resistance Rs which is series-connected to the inductance L
0
and is independent of a frequency, the inductance L
0
[&mgr;H] at 10 MHz satisfies inequality (24):
L
0
≦1.4
[&mgr;H]
  (24)
The magnetic head coil is characterized in that the inductance L
0
[&mgr;H] at 10 MHz, and the RF resistance Rp
0
[&OHgr;] at 20 MHz and the DC resistance Rs [&OHgr;] satisfy inequalities (25) and (27):
Rp
0
≧
L
0
×1200  (25)
Rs
≦6[&OHgr;]  (27)
The magnetic head coil is characterized in that the inductance L
0
[&mgr;H] at 10 MHz, and the RF resistance Rp
0
[&OHgr;] at 20,MHz satisfy inequality (26):
Rp
0
≧
L
0
×1500  (26)
The magnetic head coil is characterized i

Affiliated with

Also associated with

Rating

High speed magnetic coil for magneto-optical 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 High speed magnetic coil for magneto-optical head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High speed magnetic coil for magneto-optical head will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3015550