Inductor devices – Coil or coil turn supports or spacers – Printed circuit-type coil
Reexamination Certificate
2001-11-20
2003-06-03
Mai, Anh T (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Printed circuit-type coil
C336S223000, C336S232000
Reexamination Certificate
active
06573821
ABSTRACT:
FIELD OF TECHNOLOGY, BACKGROUND, AND SUMMARY
The invention relates to a system comprising a transformer which has a first and a second transformer winding and a first magnetic layer, which first magnetic layer is laminated in a multilayer printed circuit board, said printed circuit board being provided with a first and a second, opposed outer surface with a pattern of conductor tracks on the first outer surface.
The invention also relates to a printed circuit board provided with a first and a second, opposed outer surface, with a pattern of conductor tracks on said first outer surface, printed circuit board which comprises a first transformer winding and a first magnetic layer.
The invention further relates to a charger device, a user device, and an apparatus, all suitable for use in the system.
Such a system and such a printed circuit board are known from O. Dezuari et al.,
Sensors and Actuators
A, 76(1999), pp. 349-355. The known printed circuit board comprises a magnetic layer with an alloy of CoFeMo as the magnetic material. This alloy is provided on a substrate of epoxy resin by means of a liquid epoxy or acrylic acid glue. The magnetic layer is patterned so as to form a rectangular or toroidal magnetic core. Between the substrate with the alloy and the outer surfaces of the printed circuit board there are epoxy resin boards which are provided with conductor track patterns at the outer surfaces. Conductor tracks at the first outer surface and at the second outer surface are interconnected with electrical conduction by means of vias. A turn of a transformer winding is formed by a conductor track on the first outer surface, a conductor track on the second outer surface, and the two vias between these conductor tracks. The turn thus lies in a plane which is substantially perpendicular to the plane of the first magnetic layer. If the magnetic layer is patterned so as to have a rectangular shape, the turns, and also the first and the second transformer winding, will be mutually parallel. The transformer windings thus form three-dimensional patterns which are coiled around the magnetic core or around a portion of the magnetic core which is constructed as a layer.
A disadvantage of the known system is that the transformer has a self-inductance of no more than 1 to 10 microHenries and is useful up to 30 kHz. The known printed circuit board is accordingly not suitable for the transfer of powers in switch mode power supplies.
It is a first object of the invention to provide a system of the kind mentioned in the opening paragraph which is suitable for the transfer of power in switch mode power supplies.
It is a second object of the invention to provide a printed circuit board of the kind mentioned in the opening paragraph which is suitable for the system according to the invention.
Further objects of the invention are the provision of a user device, a charger device, and an apparatus suitable for the system according to the invention.
The first object is achieved in that
the transformer comprises a primary part, a secondary part, and an insulation layer, which insulation layer lies between the primary and the secondary part,
the primary part comprises the first transformer winding and the first magnetic layer, which first transformer winding is constructed as a two-dimensional pattern of conductor tracks, is laminated in the printed circuit board between the first magnetic layer and the insulation layer, and is electrically connected to the pattern of conductor tracks at the first outer surface, and
the secondary part comprises the second transformer winding and a second magnetic layer, which second transformer winding lies between the second magnetic layer and the insulation layer.
The transformer in the system according to the invention differs constructionally from the transformer in the known system. Thus a second magnetic layer is present besides the first in the system according to the invention. Furthermore, the first and the second transformer winding lie in a plane which is substantially parallel to the magnetic layers. In addition, the first and the second transformer winding are present between the first and the second magnetic layer.
It is found that the transformer in the system according to the invention is capable of generating a sufficiently strong magnetic field. The self-inductance of the transformer in the system according to the invention is 1 to 10 milliHenries, i.e. a factor 1000 better than in the transformer in the known system. In addition, the transformer in the system according to the invention can be used with frequencies up to a few hundreds of kHz. A coupling of 0.95 or higher is realized with lateral dimensions of a few square centimeters, with a Q-factor of the order of 10 to 40. Accordingly, the system according to the invention is highly suitable for power transfer in switch mode power supplies.
The system according to the invention may comprise a printed circuit board in which both the primary and the secondary part have been laminated. The transformer in the system, however, also operates if the primary and the secondary part are kept at some distance from one another, highly preferably substantially parallel to one another. The primary part may thus be integrated into a charger device, and the secondary part may be integrated into a user device. The user device may be charged by means of the charger device in a contactless manner in the system according to the invention.
Such a system for contactless charging is used inter alia in electric tooth brushes. This known system comprises, besides an electric tooth brush in which a battery and a coil are present, also a charger device with a coil. The charger device is provided with a ring in which the user device can be placed. The contactless charging operation takes place by the air coil principle; when the user device is placed in the ring of the charger device, the coils are concentric and transfer of energy can take place through the air. It is a disadvantage of the known system that dissipation of energy takes place also when the user device is not placed in the ring. This is undesirable for economic and environmental reasons. This disadvantage is obviated in the system according to the invention. Whereas the known system for contactless charging achieves a coupling of no more than 38%, the system according to the invention is capable of realizing a coupling of 95% or higher. When the user device is not present on the charger device, the power dissipated by the first transformer winding is small. The surface area of a turn in the transformer winding is in fact comparatively small, and the turns are preferably thin. In addition, the construction with transformer windings and magnetic layers which are mutually substantially parallel leads to a transformer which is more efficient than the transformer in the known system.
It is not necessary in the system according to the invention for a printed circuit board to be present both in the charger device and in the user device, in which printed circuit board a layered magnetic layer and a transformer winding constructed as a two-dimensional pattern of conductor tracks have been integrated. In a favorable embodiment, the magnetic layer in the user device is constructed as a component which is placed on the printed circuit board, and the transformer winding is present at the outer surface of the printed circuit board. The charger device then may have a larger surface area than the user device; several user devices may be charged with one and the same charger device contactlessly and simultaneously in this manner. In addition, the charger device may be integrated in an object such as, for example, a fruit bowl or a shelf in a bathroom cabinet. A charger device is regarded as an untidy item by many consumers. The integration of the charger device in an object such as a fruit bowl renders the charger device invisible while at the same time making it readily available for use.
Examples of user devices according to the invention are inter alia an electric too
Barakat El Hassan
Peels Wilhelmus Gerardus Maria
Van Laar Jan
Vos Hendricus Theodorus
Koninklijke Philips Electronics , N.V.
Mai Anh T
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