This application is based upon and claims the benefit of priority from Japan Patent Application No. 2011-000248, filed on Jan. 4, 2011, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a charging AC adaptor, and more particularly, to a charging AC adaptor which can be used in common for various portable devices by using an insulating air core transformer formed on a printed circuit board.
A schematic circuit configuration of a conventional charging AC adaptor with a dedicated cable connection, which uses an iron core insulating transformer (also called a magnetic core transformer), is shown in
As shown in
As shown in
In the conventional chopper type charging AC adaptor 24b, the ferrite core high frequency transformer 11 may become more compact with an increase in the chopper frequency fc. On the other hand, a power loss of a transistor arranged within the chopper circuit 5 and performing a switching operation with the chopper frequency is increased with an increase in the chopper frequency fc. Accordingly, the conventional chopper type charging AC adaptor 24b has a trade-off between the compactness of the ferrite core high frequency transformer 11 and the power loss of the transistor performing the switching operation with the chopper frequency, and was designed to provide an optimal trade-off
As a power supply system for supplying power to a mobile electronic apparatus such as a mobile phone, a notebook computer, a digital camera, an electronic toy or the like, there has been proposed a power supply system that can supply power to different kinds of electronic apparatuses by a single power transmitter (for example, see Japanese Patent Laid-Open Publication No. 2005-110409). The power supply system disclosed in Japanese Patent Laid-Open Publication No. 2005-110409 is composed of a power transmitter including a primary coil and a primary circuit that provides a pulse voltage, which is generated by switching a DC voltage obtained by rectifying commercial power, to the primary coil; and a portable telephone set including a secondary coil magnetically coupled to the primary coil and a secondary circuit that rectifies and smoothes an induction voltage induced to the secondary coil. A non-contact power supply system has also been proposed (for example, see Japanese Patent Laid-Open Publication No. 2006-211803, Japanese Patent Laid-Open Publication No. 2007-151264, Japanese Patent Laid-Open Publication No. 2002-118988, Japanese Patent Laid-Open Publication No. 2002-118988, Japanese Patent Laid-Open Publication No. 2007-312585, Japanese Patent Laid-Open Publication No. 2003-193717, Japanese Patent Laid-Open Publication No. 2001-019120, Japanese Patent Laid-Open Publication No. 2006-314151, and Japanese Patent Laid-Open Publication No. 2005-006459).
The present disclosure provides some embodiments of a charging AC adaptor which is capable of being used in common for various portable devices, such as mobile phone terminals, notebook computers, and so on, incorporating a charging battery and capable of maintaining power transmission efficiency and preventing a leakage magnetic flux from having an effect on mounted parts of the charging AC adaptor.
According to one embodiment of the present disclosure, there is provided a charging AC adaptor including: a first diode bridge connected to an AC terminal; a chopper controller connected to the first diode bridge; an insulating air core transformer connected to the chopper controller; a second diode bridge connected to a secondary side of the insulating air core transformer; a DC output terminal connected to the second diode bridge; and a common connection cable connected to the DC output terminal, wherein the charging AC adaptor may be connected to a portable device via the common connection cable.
An embodiment of the present disclosure will now be described with reference to the drawings. Throughout the drawings, the same or similar elements are denoted by the same or similar reference numerals. It should be noted that figures of the drawings are just schematic and are different in reality. It should be also understood that the figures include portions having different numerical relationships and ratios.
The following embodiment is to illustrate apparatuses and methods embodying the principles of the present disclosure and is not intended to be limited to the arrangement of elements which are described in the specification. The embodiment of the present disclosure may have various modifications according to the claims.
In the charging AC adaptor 24 according to the embodiment, a voltage obtained by bridge-rectifying an AC voltage of the AC terminal by means of the first diode bridge 2 is converted into a low voltage in the chopper controller 4. Accordingly, the charging AC adaptor 24 according to the embodiment has an automatic voltage adjustment function (AutoVolt) corresponding to an AC input of the AC voltage.
The charging AC adaptor 24 according to the embodiment can determine an input DC voltage of the portable device and supply a supply voltage adjusted to the input DC voltage to the portable device, so that a connection cable having no voltage dependency can be applied. Thus, the shape of the connection cable can be standardized. This allows the charging AC adaptor 24 according to the embodiment to be used in common for various kinds of portable devices.
In the charging AC adaptor 24 according to the embodiment, power loss due to no-load driving of leakage inductance when a portable device is not connected to the charging AC adaptor 24 is reduced, power is not consumed except for detection by polling of a connected portable device, and an LED indicator 17 is turned on only during a charging operation, thereby reducing average standby power to 1 mW or less.
In addition, when a portable device is connected to the charging AC adaptor 24 according to the embodiment, the portable device can transmit feedback information including detection information of the input voltage to the charging AC adaptor 24 via the common connection cable 8c and the charging AC adaptor 24 can receive the feedback information via the DC output terminal 16 and transmit it to the chopper controller 4 via the insulating air core transformer 12. That is, bi-directional communication can be conducted between the chopper controller 4 and the charging profile IC 14, as indicated by an arrow A in
In the charging AC adaptor 24 according to the embodiment, the chopper controller 4 controls a tuning by detecting a primary side resonance frequency and a secondary side resonance frequency of the insulating air core transformer 12.
In addition, the charging AC adaptor 24 according to the embodiment is slightly larger than but is as light as a conventional mobile phone charging AC adaptor, while being smaller than a conventional notebook computer charging AC adaptor. The charging AC adaptor 24 according to the embodiment has an advantage in that it is fixedly installed in a home/school/office and is not moved along with portable devices, and typical portable information devices can all be charged/driven in common
Referring to
Further, as shown in
Although it is illustrated in
Although not shown, the primary coils L11 and L12 formed on the front and rear surfaces of the board 10 are connected to each other via a through hole formed in the board 10 and, similarly, the secondary coils L21 and L22 formed on the front and rear surfaces of the board 10 are connected to each other via another through hole formed in the board 10.
In addition, as shown in
The ferrite core high frequency transformer 11 as a closed magnetic circuit using a ferrite core in the comparative example basically differs from the insulating air core transformer 12 in that the former is a wide band transformer having more magnetic fluxes, whereas the latter, as an opened magnetic circuit, is a narrow band transformer having fewer magnetic fluxes. As a result, the charging AC adaptor 24 according to the embodiment can suppress the effect of a leakage magnetic flux on adjacent mounted parts P1 to P3, i.e., an effect of a leakage magnetic flux on mounted parts of the charging AC adaptor 24.
In addition, due to the existence of the adjacent mounted parts P1 to P3, the wide band ferrite core high frequency transformer 11 of the comparative example has low variation of its operating point while the insulating air core transformer 12 applied to the charging AC adaptor 24 according to the embodiment has the tendency of a shift of its resonance frequency. However, these effects are automatically absorbed to not provide a problem.
A conventional non-contact charger of a closed magnetic circuit attempts to reduce the leakage magnetic flux as possible but the charging AC adaptor 24 of an opened magnetic circuit according to the embodiment can suppress the effect of a leakage magnetic flux on the mounted parts. That is, in the charging AC adaptor 24 according to the embodiment, by making a tuning with the addition of the resonance capacitors C1 and C2 to the primary coils L11 and L12 and the secondary coils L21 and L22, respectively, excitation inductance in the air coil is equivalently multiplied by Q and the primary coils L11 and L12 and the secondary coils L21 and L22 are coupled to each other with extremely low impedance. This prevents an effect of impedance as a short ring of adjacent alien substance.
In the charging AC adaptor 24 according to the embodiment, the insulating air core transformer 12 has a magnetic coupling coefficient of 0.8 or more and an unloaded Q value of 50 or more. As a result, a total power transmission efficiency of 80% or more can be maintained.
The board 10 may be, for example, a printed circuit board.
A typical printed circuit board increases in terms of its series resistance when an insulating air core transformer having a conductive pattern is formed on the board since the thickness of a conductive layer is set to, for example, 35 μm. Accordingly, an insertion loss of a high frequency insulating transformer may be reduced by increasing the thickness of the conductive layers of both front and rear surfaces of the printed circuit board using a process of attaching copper with electro-plating in a through hole forming process of two or more layers of printed circuit boards in order to alleviate an increase of the insertion loss of the high frequency insulating transformer.
Whereas a conventional transformer concept has pursued an ideal transformer operating in a wide band, the insulating air core transformer 12 applied to the charging AC adaptor 24 according to the embodiment can operate in an extremely narrow single frequency band with complete exclusion of this concept.
The insulating air core transformer 12 applied to the charging AC adaptor 24 according to the embodiment can achieve high excitation impedance by adding the resonance capacitors, as shown in
From the standpoint of a conventional concept of transformer design, a first defect of an air core is that excitation inductance becomes small and accordingly current flows into the air core to prevent power from being delivered to a secondary side. However, this can be easily overcome by increasing excitation impedance at a tuning frequency by Q times through the resonance.
A second defect of the air core is that a magnetic coupling coefficient is smaller than that of a cored transformer since the air core transformer is an opened magnetic circuit. However, this can be also overcome by the resonance.
A third defect of the air core is that a magnetic flux is leaked having an effect on other mounted parts on a single board of a charger since the air core transformer is an opened magnetic circuit. However, this can be relatively overcome since the primary and secondary sides have low impedance. There is no defect of the air core other than these defects.
Power transmission efficiency η of the resonance type insulating air core transformer 12 applied to the charging AC adaptor 24 according to the embodiment is approximately expressed by Equation 1.
In the above equation, X is winding reactance, k is a magnetic coupling coefficient between the primary coil and the secondary coil, r is winding resistance and R is load resistance. A symbol * represents multiplication.
The charging AC adaptor 24 according to the embodiment can achieve a reduction of cost by forming the insulating air core transformer 12 with a conductive pattern on the printed circuit board. In addition, by subjecting a feedback from the secondary side to the primary side of the insulating air core transformer 12 to carrier modulation through the insulating air core transformer 12 from a photo-coupler, the number of parts and costs can be reduced. In addition, since the charging AC adaptor 24 is not required to be packed with a portable information device, by using the standardized charging AC adaptor 24 in common, reduction of costs can be achieved.
The charging AC adaptor 24 used in common according to the embodiment may be available at a low price and can charge/drive a portable device of, for example, 3 W to 10 W. In addition, the charging AC adaptor 24 may be left in a home/school/office without being carried and may be shared between persons with mutual concessions.
The charging AC adaptor 24 used in common according to the embodiment is slightly larger than an existing mobile phone charger while being smaller and lighter than an existing notebook computer charging AC adaptor.
With application of the insulating air core transformer 12 instead of a ferrite core high frequency transformer, the charging AC adaptor 24 according to the embodiment can improve the trade-off between compactness of the high frequency transformer and power loss of a transistor performing a switching operation with a chopper frequency.
In addition, by standardizing connectors connecting a portable device and the charging AC adaptor 24 and relevant protocols, the charging AC adaptor 24 according to the embodiment can be used in common in portable devices including a mobile phone and a notebook without relying on the types of portable devices.
In addition, the charging AC adaptor 24 according to the embodiment can provide bi-directional communication between a charging profile IC of a portable device and the chopper controller 4 of the charging AC adaptor 24 via a standardized cable and an insulating air transformer.
The charging AC adaptor 24 according to the embodiment can standardize a charging/driving method of a portable device and maintain power transmission efficiency by an insulating air core transformer formed by a conductive pattern on a board, thereby suppressing the effect of a leakage magnetic flux on mounted parts of the charging AC adaptor 24.
The charging AC adaptor 24 according to the embodiment can be significantly reduced in its production costs by using a charging AC adaptor/charger of a portable device in common for other portable devices including a mobile phone and a notebook computer with any voltage/current, standardizing cables/connectors/protocols, and forming the insulating air core transformer 12 with a conductive pattern on a printed circuit board.
The present disclosure can provide a charging AC adaptor which is capable of being used in common for various portable devices including mobile phones and notebook computers incorporating a charging battery, maintaining power transmission efficiency and suppressing the effect of a leakage magnetic flux on mounted parts of the charging AC adaptor.
Although the present disclosure has been described by way of an embodiment, the description and the drawings, both of which are parts of the specification, are not intended to limit the present disclosure. It is apparent to those skilled in the art that the present disclosure may be modified and changed in different forms of embodiments, examples and operation techniques.
According to the present disclosure, it is possible to provide a charging AC adaptor which is capable of being used in common for portable devices including mobile phones and notebook computers incorporating a charging battery, maintaining power transmission efficiency and suppressing the effect of a leakage magnetic flux on mounted parts of the charging AC adaptor.
The charging AC adaptor according to the above embodiment can be applied to various portable devices since it is fixedly installed in a home/school/office and is not moved along with the portable devices. Typical portable information devices can all be charged/driven in common by the charging AC adaptor of the present disclosure.
While a certain embodiment has been described, this embodiment has been presented by way of example only, and is not intended to limit the scope of the disclosures. Indeed, the novel methods and apparatuses described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiment described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures.
Number | Date | Country | Kind |
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2011-000248 | Jan 2011 | JP | national |