Inductor devices – Core surrounding linear conductor
Reexamination Certificate
2000-02-18
2002-03-12
Mai, Anh (Department: 2832)
Inductor devices
Core surrounding linear conductor
C336S178000, C336S092000
Reexamination Certificate
active
06356179
ABSTRACT:
TECHNICAL FIELD
This invention relates to an inductance element, for example, for use in power supply units of computers.
BACKGROUND ART
FIG. 8
shows an example of a circuit of a step-down type DC/DC converter for use in the power supply unit of computers. Reference numeral
101
denotes a control IC, reference symbol VB denotes a source of voltage supply, reference numeral
102
denotes a switching circuit, reference numeral
103
denotes a load for CPU or others, and reference numeral
106
denotes a capacitor.
The switching circuit
102
consists of switching devices
105
a
,
105
b
connected to output terminals S, T for driving of the control IC
101
, and an inductance device
104
connected between an output terminal U of the switching devices
105
a
,
105
b
and the load
103
.
In the above construction, load current from several amperes to dozens of amperes flows through the load
103
connected between an output side of the inductance device
104
and earth, and at the same time high current flows through the inductance device
104
. The inductance value of the inductance device
104
is varied in response to variation in load and switching operation of the switching circuit
102
. Therefore, when the inductance value of the inductance device
104
is varied, the operation of the switching circuit
102
becomes unstable. By the way, in a conventional manner, because operating (switching) frequency of the control IC
101
and the switching devices
105
a
,
105
b
used for the above circuit is not so high, as the inductance device
104
used for the switching circuit
102
, one whose inductance value is about dozens of &mgr;H (micro henries) has been used. Moreover, as the construction of the inductance device
104
above, for example, wide-core wire is merely wound around a wide-core drum-shaped ferrite core at a predetermined number of times.
In recent years, along with the advance of technology, the operating frequency of the control IC
101
and the switching devices
105
a
,
105
b
above becomes quite high, as the inductance device used for the DC/DC converter circuit above, one whose inductance value is not more than 1 &mgr;H has been required.
Furthermore, together with the control IC
101
and the switching devices
105
a
,
105
b
, the performance of CPU has been improved to speed up. If said CPU is applied as the load of the DC/DC converter circuit, the CPU will be very heavy load therefor (the load current will be very high). However, the inductance device of construction in which wire is wound around the conventional drum-shaped ferrite core is difficult to make the inductance value thereof minute value of not more than 1 &mgr;H, cannot provide stable inductance value when high current about dozens of amperes flows, and also is in the difficult state to be minimized in the dimensions.
The present invention is made to meet the requests for the inductance device above, and an object thereof is to provide an inductance device whose dimensions can be minimized, which has an inductance value of not more than 1 &mgr;H, and whose DC characteristic is almost flat even if high current flows.
SUMMARY OF THE INVENTION
In order to achieve the above object, an inductance device according to the present invention for use in power supply units is characterized in that a slit is provided on one surface of a polygonal cylindrical ferrite core in the same direction to the depth direction of a tube hole, and a conductor is inserted through the tube hole. Besides, the inductance device is further characterized in that the conductor is wound to pass through into said tube hole two or more times. Moreover, the inductance device is characterized in that the conductor is a plate one.
Besides, the inductance device according to the present invention for use in power supply units is characterized in that the ferrite core is shaped into square cylindric, a slit is provided in one side of the ferrite core in the same direction to a hollow portion to form an open magnetic path, and a belt-like conductor is inserted through the hollow portion. Moreover, the inductance device is characterized in that each end of the belt-like conductor inserted through the hollow portion of the square cylindrical ferrite core is formed into a surface mount terminal.
REFERENCES:
patent: 5321373 (1994-06-01), Shusterman et al.
patent: 5783978 (1998-07-01), Noguchi et al.
patent: 5844462 (1998-12-01), Rapoport et al.
patent: 6144279 (2000-11-01), Collins et al.
patent: 2228008 (1990-09-01), None
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