United States Patent [19]
`Faulk
`
`USOO5818705A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,818,705
`*Oct. 6, 1998
`
`[54] PORTABLE COMPUTER HAVING BUILT-IN
`AC ADAPTER INCORPORATING A SPACE
`EFFICIENT ELECTROMAGNETIC
`INTERFERENCE FILTER
`
`[75] Inventor: Richard A‘ Faulk> Cypress> TeX-
`[73] Assignee: Compaq Computer Corporation,
`Houston, TeX.
`
`[ * ]
`
`Notice:
`
`The term of this patent shall not eXtend
`beyond the expiration date of Pat. No.
`5’636’112'
`
`[21] Appl' N05 828,749
`[22]
`Filed,
`Man 26’ 1997
`
`Related US Application Data
`
`[63] Continuation of Ser_ No_ 502,197’ _[u]_ 13’ 1995’ Pat NO_
`5,636,112.
`[51] Int. Cl? ............................ .. H02M 1/12- H02M 1/14
`[52] U S C]
`363/48 363/45
`_'
`'
`' """""""""""""""""""""""""" "
`’
`Fleld of Search ................................ ..
`
`45, 47,
`363/48’ 50’ 53
`
`[56]
`
`References Cited
`
`U_S_ PATENT DOCUMENTS
`
`4,580,112
`4,849,950
`5,080,218
`5,142,439
`5,148,095
`
`4/1986 Winslow et al. ....................... .. 333/12
`7/1989 Sugiura et al. .
`1/1992 IZume et al..
`8/1992 Huggett et al. .
`9/1992 Miller et al. .
`
`5,636,112
`
`6/1997 Faulk ...................................... .. 363/48
`
`Primary Examiner—Stuart N. Hecker
`[57]
`ABSTRACT
`
`An internal AC adapter Which incorporates a space ef?cient
`EMI ?lter is positioned Within a main chassis portion of a
`portable personal computer having at least one energy
`demanding component also positioned Within the main
`chassis portion. The internal AC adapter, Which converts
`alternating current received from an alternating current main
`to direct current for transmission to the energy-demanding
`components, includes a ?rst connector for electrically con
`necting the internal AC adapter to the alternating current
`main, a bridge recti?er circuit having an AC input side
`electrically connected' to the ?rst connector' and a DC output
`side and a space ef?cient electromagnetic interference ?lter
`having an input side electrically connected to the DC output
`side of the bridge recti?er circuit and an output side. The
`bridge recti?er circuit converts alternating current received
`from the ?rst connector to direct current for transmission to
`the elearemagne?c interfqence ?n“ I“ “m the 61.6680‘
`magnetic interference ?lter includes at least one capac1tat1ve
`element for ?ltering noise from the direct current transmitted
`thereto
`the
`recti?er Circuit' The ?ltered direct
`current is then transmitted to the energy-demanding com
`ponents electrically connected to the output side of the
`electromagnetic interference ?lter. By placing the electro
`magnetic interference ?lter on the DC output side of the
`bridge recti?er circuit, reduced siZe capacitors such as a
`multilayer Ceramic Capacitor may be used as the capacitative
`
`element‘
`
`18 Claims, 3 Drawing Sheets
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`35
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`____ ___j_____
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`WAC 1005
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`

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`U.S. Patent
`
`Oct.6,1998
`
`Sheet 1 of3
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`5,818,705
`
`FIG.
`(PRIOR ART)
`
`37
`_______\________
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`r I I I I I [1
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`1 l I l I I ll
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`FIG. 7B
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`

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`U.S. Patent
`US. Patent
`
`Oct.6,1998
`Oct. 6, 1998
`
`Sheet 2 of3
`Sheet 2 0f 3
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`5,818,705
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`

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`U.S. Patent
`
`Oct.6,1998
`
`Sheet 3 of3
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`5,818,705
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`FIG. 4
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`69
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`FIG. 5
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`

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`1
`PORTABLE COMPUTER HAVING BUILT-IN
`AC ADAPTER INCORPORATING A SPACE
`EFFICIENT ELECTROMAGNETIC
`INTERFERENCE FILTER
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`
`This is a continuation of application Ser. No. 08/502,197,
`?led Jul. 13, 1995, noW issued as U.S. Pat. No. 5,636,112.
`This application is related to US. patent application Ser.
`No. 08/502,198, noW U.S. Pat. No. 5,625,535 entitled
`“Compact Construction for Portable Computer PoWer
`Supply”, ?led on even date hereWith, assigned to the
`Assignee of the present application and hereby incorporated
`by reference as if reproduced in its entirety.
`
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`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The invention relates to portable computers having built
`in AC adapters and, more particularly, to a built-in AC
`adapter positioned in a main chassis portion of a portable
`computer and having a space ef?cient electromagnetic inter
`ference ?lter incorporated thereWith.
`2. Description of Related Art
`Portable, battery-poWered computers have become
`increasingly popular in recent years due to their light Weight
`and small siZe that permit them to be easily hand-carried in
`an ordinary briefcase and used by business travelers in
`cramped spaces lacking electrical plug-in facilities, for
`example, airline seat back trays. In fact, a particularly small
`type of portable computer, the notebook computer, Which
`enjoys Widespread popularity today is generally character
`iZed by dimensions of 8.5“><11“and a Weight of less than 8
`pounds. More recent developments in computer miniatur
`iZation have resulted in so-called “subnotebook” computers
`having still smaller dimensions and even loWer Weights.
`The modern portable computer is typically comprised of
`a pivoting display screen portion and a main chassis portion
`in Which a keyboard, both hard and ?oppy disk drives, and
`possibly other components, for example, a modem or PCM
`CIA slot, are incorporated. Also provided on the main
`chassis portion is at least one port for coupling the portable
`computer to a peripheral device, for example, a printer.
`Thus, the portable computer is a fully self-contained com
`puter system suitable for use, for at least short periods of
`time, in situations and locations in Which the use of a much
`larger desktop computer is simply not feasible.
`As is Well-knoWn, hoWever, even state-of-the-art portable
`computers have certain limitations and disadvantages When
`compared to their much larger desktop computer counter
`parts. One principal disadvantage is that portable computers
`are battery-poWered and thus are operable only When the
`battery is sufficiently charged. Fortunately, hoWever, almost
`all battery-poWered portable computers are sold With an AC
`adapter. When plugged into an AC main or other convenient
`source of AC poWer, the AC adapter converts the poWer into
`a form usable by the portable computer. The AC adapter
`includes a line cord that plugs into the AC poWer source and
`an adapter cord that plugs into a designated poWer supply
`port, typically located on a back side portion of the main
`chassis of the portable computer. PoWer conversion is per
`formed in a poWer supply coupled betWeen the line cord and
`adapter cord and housed in a poWer supply chassis Which is
`separate from the main chassis.
`There are historical reasons for the poWer supply being
`housed in a separate poWer supply chassis. Because of
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`notoriously tight volumetric constraints in the main chassis
`of a portable computer, the components and subsystems
`thereof have, for years, been the subject of constant, exten
`sive design Work directed toWard making such components
`and subsystems as small as possible. Because the main
`chassis has alWays been fully occupied With necessary
`components and subsystems, there Was no motivation to
`attempt to ?t in less vital subsystems, such as the poWer
`supply. Thus, because prior art poWer supplies have been
`entirely external to the portable computer, they Were never
`subjected to the intense miniaturiZation effort otherWise
`applied to the portable computer.
`Accordingly, the various components of the external
`poWer supply have remained relatively bulky. For example,
`poWer supplies typically include heat-producing compo
`nents Which require heat sinks to dissipate generated heat
`before the accumulated heat can damage nearby electronic
`devices. In the past, such heat dissipation Was accomplished
`by physically mounting thermally conductive structures
`having bulky and heavy ?ns or projections to the heat
`producing components. Thus, for these and other reasons,
`such prior art external poWer supplies have been large,
`heavy and cumbersome, earning them the un?attering col
`loquial term “brick.” The bulky and clumsy “brick” stood in
`stark contrast to the otherWise elegant and compact design of
`prior art portable computers. Moreover, the external poWer
`supply has made the portable computer much more difficult
`to transport, thereby detracting from the ease of use of such
`devices.
`While the relocation of the external poWer supply Within
`the portable computer Would solve many problems Which
`result from the external poWer supply, the relatively bulky
`siZe of the poWer supply and the tight volumetric require
`ments of components Within the portable computer has
`prevented such a relocation. To accomplish this task, not
`only Would additional space need to be made available
`Within the chassis of the portable computer, the poWer
`supply itself Would need to undergo the same type of
`miniaturiZation effort through Which the rest of the portable
`computer has already undergone. HoWever, any proposed
`miniaturiZation or other reduction in siZe of a poWer supply
`Would prove a dif?cult task and Would likely entail an
`electrical redesign of the poWer supply in order to effect a
`minimiZation of the siZe of the components thereof.
`In US. patent application Ser. No. 08/502,198 now US.
`Pat. No. 5,625,535 , ?led on even date hereWith and previ
`ously incorporated by reference, an internal poWer supply
`Which incorporates a space ef?cient heat dissipation struc
`ture Was disclosed. The disclosed heat dissipation structure
`eliminates the need for the relatively large heat sinks pres
`ently in use in external poWer supplies. There are, hoWever,
`other internal components of the poWer supply Which unnec
`essarily consume large amounts of space and Which should
`also be the subject of siZe reduction efforts.
`One such component is the aforementioned AC adapter.
`As previously stated, the function of the AC adapter is to
`convert high voltage AC poWer provided from the AC main,
`for example, an electrical outlet, to loW voltage DC poWer
`suitable for use by the portable computer. Traditionally, the
`AC adapter has been located Within the external poWer
`supply housing previously described herein. While it Would
`be desirable to locate the AC adapter Within the main
`housing chassis of the portable computer, certain design
`considerations has caused the AC adapter to be too large to
`?t Within the relatively small space available Within the main
`housing chassis.
`Like all electronic devices, the AC adapter generates noise
`during the operation thereof. While no limits on such noise
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`5,818,705
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`3
`Were initially imposed, to prevent noise generated by an
`electronic device from interfering With radio, television,
`navigational equipment or other devices, the FCC imposed
`a series of increasingly stringent regulations Which limit the
`amount of transmitted and/or conducted noise signals Which
`may escape from an electronic device. Accordingly, all AC
`adapters are equipped With an electromagnetic interference
`(or “EMI”) ?lter to remove high frequency noise generated
`thereby. In turn, the design of an AC adapter having an EMI
`?lter Which removed suf?cient noise such that the AC
`adapter Was in compliance With FCC regulations caused the
`AC adapter, and certain ones of its components, speci?cally,
`the EMI ?lter, to become relatively large in siZe.
`Speci?cally, the EMI ?lter is comprised of plural capaci
`tative and inductive elements located betWeen an AC con
`nector and a bridge recti?er circuit of the AC adapter.
`Various governmental regulatory agencies, particularly in
`Europe, have very strict requirements for components
`located across a high voltage AC line. Thus, as the compo
`nents of the EMI ?lter have traditionally been located
`betWeen the AC main and the bridge recti?er circuit, they
`have been subject to these requirements.
`More speci?cally, such governmental regulatory agencies
`typically require that a capacitor located across the high
`voltage AC line be a type “X” capacitor. Thus, in order to
`comply With this regulation, the capacitors of the EMI ?lter
`Which are located betWeen the AC connector and the bridge
`recti?er must be of type “X”. HoWever, type “X” capacitors
`are subject to stringent safety requirements Which cause
`such capacitors to be relatively large and bulky. For
`eXample, a 0.10 pF type “X” capacitor takes up 0.118 cubic
`inches of space While a 0.22 pF type “X1” capacitor takes up
`0.192 cubic inches of space. Thus, an AC adapter having an
`EMI ?lter located betWeen the AC line and the bridge
`recti?er Which respectively includes as the capacitor C1 and
`the capacitor C2, 0.10 MF and 0.22 pF type “X1” capacitor,
`to provide the necessary amount of ?ltering Would consume
`0.31 cubic inches of space merely for the capacitors of the
`EMI ?lter alone. Such an AC adapter Would likely be
`considered too bulky to be suitable for placement Within the
`main chassis of a portable computer.
`As all capacitor and inductor components of the EMI ?lter
`have traditionally been located betWeen the AC main and the
`bridge recti?er circuit, such components have tended to be
`relatively large. What is needed in the art is a reduced siZe
`EMI ?lter suitable for use With an AC adapter portion of a
`poWer supply. If such an AC adapter Were achieved, the
`volume of the poWer supply Would be reduced such that the
`poWer supply could be made to ?t Within the con?nes of the
`main chassis portion of a portable computer system. It is,
`therefore, an object of the present invention to provide such
`a internal poWer supply for a portable computer.
`
`SUMMARY OF THE INVENTION
`
`In one embodiment, the present invention is of a volume
`ef?cient line ?lter Which includes a ?rst connector for
`electrically connecting the AC adapter to an alternating
`current main, a bridge recti?er circuit having an AC input
`side electrically connected to the ?rst connector, an electro
`magnetic interference ?lter having an input side electrically
`connected to a DC output side of the bridge recti?er circuit
`and a second connector for electrically connecting a DC
`output side of the electromagnetic interference ?lter and a
`DC output line. The bridge recti?er circuit converts alter
`nating current received from the ?rst connector to direct
`current for transmission to the electromagnetic interference
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`4
`?lter for noise removal. In various aspects thereof, the
`electromagnetic interference ?lter may include a multilayer
`ceramic capacitor electrically connected in parallel With the
`DC output side of the bridge recti?er circuit, ?rst inductor
`means, electrically connected in parallel With the multilayer
`ceramic capacitor, for providing a common mode choke of
`line noise and second inductor means, electrically connected
`to the ?rst inductor means, for providing a differential mode
`choke of line noise. In another aspect thereof, the volume
`ef?cient line ?lter may also include a bulk capacitor, elec
`trically connected to the ?rst and second inductor means, for
`converting direct current output by the bridge recti?er circuit
`into stored energy for transfer to the DC output line.
`In another embodiment, the present invention is of a
`volume ef?cient poWer supply for converting alternating
`current from an alternating current main to direct current
`suitable for output to a DC output line. The volume ef?cient
`poWer supply includes a ?rst connector for electrically
`connecting the poWer supply to the alternating current main,
`a bridge recti?er circuit having an AC input side electrically
`connected to the ?rst connector, an electromagnetic inter
`ference ?lter having an input side electrically connected to
`a DC output side of the bridge recti?er circuit and a second
`connector for electrically connecting a DC output side of the
`electromagnetic interference ?lter and a DC output line. The
`bridge recti?er circuit converts alternating current received
`from the ?rst connector to direct current for transmission to
`the electromagnetic interference ?lter for noise removal. In
`various aspects thereof, the electromagnetic interference
`?lter may include a multilayer ceramic capacitor electrically
`connected in parallel With the DC output side of the bridge
`recti?er circuit, ?rst inductor means, electrically connected
`in parallel With the multilayer ceramic capacitor, for pro
`viding a common mode choke of line noise and second
`inductor means, electrically connected to the ?rst inductor
`means, for providing a differential mode choke of line noise.
`In a further aspect thereof, the volume ef?cient AC
`adapter may also include a bulk capacitor, electrically con
`nected to the ?rst and second inductor means, for converting
`direct current output by the bridge recti?er circuit into stored
`energy for transfer to energy demanding components
`coupled to the DC output line. In further aspects of this
`embodiment of the invention, the volume efficient poWer
`supply is coupled to a portable personal computer and
`preferably housed Within a main chassis portion thereof.
`In yet another embodiment, the present invention is of a
`volume ef?cient AC adapter for converting alternating cur
`rent from an alternating current main to direct current
`suitable for use by a portable personal computer. The
`volume ef?cient AC adapter includes a ?rst connector for
`electrically connecting the AC adapter to the alternating
`current main, a bridge recti?er circuit having an AC input
`side electrically connected to the ?rst connector, an electro
`magnetic interference ?lter having an input side electrically
`connected to a DC output side of the bridge recti?er circuit
`and a second connector for electrically connecting a DC
`output side of the electromagnetic interference ?lter and the
`portable personal computer. The bridge recti?er circuit con
`verts alternating current received from the ?rst connector to
`direct current for transmission to the electromagnetic inter
`ference ?lter for noise removal. In various aspects thereof,
`the electromagnetic interference ?lter may include a multi
`layer ceramic capacitor electrically connected in parallel
`With the DC output side of the bridge recti?er circuit, ?rst
`inductor means, electrically connected in parallel With the
`multilayer ceramic capacitor, for providing a common mode
`choke of line noise and second inductor means, electrically
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`5,818,705
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`connected to the ?rst inductor means, for providing a
`differential mode choke of line noise.
`In further aspects thereof, the volume efficient AC adapter
`may also include a bulk capacitor, electrically connected to
`the ?rst and second inductor means, for converting direct
`current output by the bridge recti?er circuit into stored
`energy for transfer to the portable personal computer, a
`transient voltage suppressor, either electrically connected in
`parallel With the AC input side of the bridge recti?er circuit
`or electrically connected in parallel With the multilayer
`ceramic capacitor, and a fuse electrically connected betWeen
`the ?rst connector and the AC input side of the bridge
`recti?er circuit.
`In still another embodiment, the present invention is of an
`internal AC adapter positioned Within a main chassis portion
`of a portable personal computer having at least one energy
`demanding component also positioned Within the main
`chassis portion. The internal AC adapter, Which converts
`alternating current received from an alternating current main
`to direct current for transmission to the energy-demanding
`components, includes a ?rst connector for electrically con
`necting the internal AC adapter to the alternating current
`main, a bridge recti?er circuit having an AC input side
`electrically connected to the ?rst connector and a DC output
`side, and a space ef?cient electromagnetic interference ?lter
`having an input side electrically connected to the DC output
`side of the bridge recti?er circuit and an output side. The
`bridge recti?er circuit converts alternating current received
`from the ?rst connector to direct current for transmission to
`the electromagnetic interference ?lter. In turn, the electro
`magnetic interference ?lter includes at least one capacitative
`element for ?ltering noise from the direct current transmitted
`thereto by the bridge recti?er circuit. The ?ltered direct
`current is then transmitted to the energy-demanding com
`ponents electrically connected to the output side of the
`electromagnetic interference ?lter. By placing the electro
`magnetic interference ?lter on the DC output side of the
`bridge recti?er circuit, reduced siZe capacitors such as a
`multilayer ceramic capacitor may be used as the capacitative
`element.
`In one aspect thereof, the multilayer ceramic capacitor or
`other reduced siZe capacitative element is electrically con
`nected in parallel With the DC output side of the bridge
`recti?er circuit. In another aspect thereof, the space ef?cient
`electromagnetic ?lter further includes at least one inductive
`element for blocking noise contained in the direct current
`transmitted to the electromagnetic interference ?lter by the
`bridge recti?er circuit. In yet another aspect, the internal AC
`adapter may also include an energy storage element such as
`a bulk capacitor electrically connected in parallel With the
`electromagnetic interference ?lter for converting direct cur
`rent output by the bridge recti?er circuit into stored energy
`for transfer to the energy-demanding components of the
`portable personal computer.
`In further aspects thereof, the internal AC adapter may
`alternately include a transient voltage suppressor electrically
`connected in parallel With the AC input side of the bridge
`recti?er circuit or a transient voltage suppressor electrically
`connected in parallel With the multilayer ceramic capacitor
`and a fuse electrically connected betWeen the ?rst connector
`and the AC input side of the bridge recti?er circuit. Finally,
`in yet another aspect of this embodiment of the invention,
`the ?rst connector may be a plug-in connector for insertably
`receiving the alternating current main. In this aspect, the
`main chassis portion Would de?ne an access aperture
`through Which the plug-in connector is accessed.
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`BRIEF DESCRIPTION OF THE DRAWING
`The present invention may be better understood, and its
`numerous objects, features and advantages Will become
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`apparent to those skilled in the art by reference to the
`accompanying draWing, in Which:
`FIG. 1A is a perspective vieW of a prior art portable
`computer and an associated external poWer supply chassis in
`Which an AC adapter is housed;
`FIG. 1B is a schematic illustration of the AC adapter
`(Which includes an EMI ?lter) housed Within the external
`poWer supply chassis of FIG. 1A;
`FIG. 2 is a partially cut-aWay perspective vieW of a
`portable computer chassis Which includes an internal poWer
`supply module;
`FIG. 3 is a partially exploded, perspective vieW of the
`portable computer chassis of FIG. 2 taken from the rear side
`thereof;
`FIG. 4 is a top plan vieW of the internal poWer supply
`module of FIG. 2 Which includes a built-in AC adapter
`constructed in accordance With the teachings of the present
`invention and incorporating a novel space ef?cient EMI
`?lter therein; and
`FIG. 5 is a schematic illustration of the built-in AC
`adapter and associated space ef?cient EMI ?lter of FIG. 4.
`
`DETAILED DESCRIPTION
`
`Referring noW to the draWing Wherein thicknesses and
`other dimensions have been exaggerated in the various
`?gures as deemed necessary for explanatory purposes and
`Wherein like reference numerals designate the same or
`similar elements throughout the several vieWs, a prior art
`portable computer 10 and an associated external poWer
`supply 12 Will noW be described in greater detail. Typically,
`the external poWer supply 12 is designed to convert alter
`nating current (or “AC”) poWer to a form usable by the
`portable computer 10. As is Well knoWn, portable computers
`are typically designed to run on direct current (or “DC”),
`Which is usually supplied by an internal DC battery (not
`shoWn). The DC battery is recharged by the user plugging
`the external poWer supply 12 into a conventional AC outlet
`that supplies the AC poWer, Which is then converted into DC
`poWer by the external poWer supply 12. Alternatively, direct
`DC operational poWer may be supplied to the portable
`computer 10 from the AC source via the external poWer
`supply 12.
`As seen in FIG. 1A, the prior art portable computer 10 has
`a base member 14 and a lid member 16 With a screen portion
`18 mounted therein. The base member 14 is comprised of a
`main chassis portion 20 that houses the internal electrical
`components of the portable computer 10. The external
`poWer supply 12 has a brick-like housing 22 that surrounds
`and houses the internal electrical components (not visible in
`FIG. 1A) of the external poWer supply 12.
`A distinct disadvantage associated With the external
`poWer supply 12 is that it often has an overall height that
`exceeds the overall height of the main chassis portion 20.
`Thus, it must be carried and used externally from the main
`chassis portion 20. Additionally, the Weight of the external
`poWer supply 12 adds substantially to the total Weight
`associated With the portable computer 10.
`The external poWer supply 12 is also cumbersome to use
`and store because of the line cords associated With it.
`Typically, the external poWer supply 12 has tWo electrical
`line cords associated With it, an AC cord 24 and a DC cord
`26, both of Which are individually connectable to the exter
`nal poWer supply 12. The AC cord 24 has a ?rst end 28 that
`is designed to be electrically connected to an AC poWer
`source (not shoWn) such as an AC main and a second end 30
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`5,818,705
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`that is designed to be electrically connected to the external
`power supply 12. The DC cord 26 has a ?rst end 32 that is
`designed to be electrically connected to the external poWer
`supply 12 and a second end 34 that is designed to be
`electrically connected to the portable computer 10. From
`these disadvantages, it is clear that a need has arisen for a
`portable computer With a light-Weight, space-ef?cient poWer
`supply that can ?t in the limited amount of space Which is
`available Within the main chassis portion of the portable
`computer.
`Referring next to FIG. 1B, an AC adapter 35 located
`Within the housing 22 of the external poWer supply 12 Will
`noW be described in greater detail. The AC adapter 35 is
`coupled to the AC main by insertably connecting the second
`end 30 of the AC cord 24 to plug connector A1. Coupled to
`the plug connector A1 is a fuse F1 Which protects the AC
`adapter 35 from short circuits and other internal faults Which
`could potentially damage the AC adapter 35 by disconnect
`ing the AC adapter 35 from the AC main upon detection of
`such fault conditions.
`Located betWeen the fuse F1 and bridge recti?er circuit
`U1 is EMI ?lter 37. The EMI ?lter 37 is comprised of a ?rst
`capacitor C1 connected across the AC line, a ?rst inductor
`L1 coupled to the ?rst capacitor C1, a second inductor L2
`connected in series With the ?rst inductor L1 and a second
`capacitor C2 coupled to the ?rst and second inductors L1
`and L2. The inductor L1 is a common mode con?gured
`choke Which ?lters noise Which is common to both lines.
`The inductor L2 is a differential mode con?gured choke
`Which ?lters noise that is differential on both lines, i.e. noise
`?oWing in one line in a positive fashion and ?oWing out the
`other line in a negative fashion. The capacitors C1 and C2
`are high quality capacitors Which form a simple attenuation
`circuit. For high frequency noise, the capacitors C1 and C2
`Will short circuit the noise across the line While the inductors
`L1 and L2 block the noise.
`The EMI ?lter 37 is coupled to an AC input side of bridge
`recti?er circuit U1. The bridge recti?er circuit U1 provides
`a full Wave recti?cation of the input AC poWer supplied
`thereto Which converts the supplied poWer to DC.
`Preferably, the bridge recti?er circuit U1 is rated at 800
`volts. Coupled to a DC output side of the bridge recti?er
`circuit U1 is a capacitor C3. The capacitor C3 is a bulk
`capacitor, preferably, one rated at 250 volts, Which provides
`energy for the poWer supply. More speci?cally, the full Wave
`recti?ed DC poWer output by the bridge recti?er circuit U1
`charges the capacitor C3. Energy-demanding components
`connected to the terminals 39, 41, for example, by plugging
`the second end 34 of the DC cord 26 into a corresponding
`DC plug (see FIG. 3) accessible from the rear side of the
`main chassis portion 20 may then draW on the poWer stored
`by the capacitor C3 as needed.
`While the EMI ?lter 37 has proven acceptable in use, the
`primary shortcoming to its continued use in portable com
`puters is that, being located on the AC side of the bridge
`recti?er circuit U1, the capacitors C1 and C2 must comply
`With the requirements for the X-type capacitor previously
`discussed. This causes the capacitors C1 and C2 to consume
`a relatively large amount of the space available Within the
`interior of the housing 22 of the external poWer supply 12,
`thereby contributing signi?cantly to the unsuitability of the
`AC adapter for placement Within the main chassis portion.
`Referring next to FIG. 2, in a preferred embodiment
`thereof, illustrated is a partially cut-aWay perspective vieW
`of a main chassis portion 36 of a portable computer having
`an internal poWer supply module 38 constructed in accor
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`15
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`35
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`55
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`65
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`8
`dance With the teachings of the present invention and, as Will
`be more fully described beloW, Which includes a built-in AC
`adapter Which has been dramatically reduced in siZe by
`virtue of the incorporation of various space efficient
`components, including a reduced volume EMI ?lter. While
`the present invention is disclosed as incorporated into a
`volume ef?cient, internal AC adapter for a portable personal
`computer, it should be clearly understood that the invention
`is equally suitable for incorporation into a volume ef?cient
`poWer supply, either for a portable personal computer or
`other energy demanding device, or a volume ef?cient line
`?lter.
`The main chassis portion 36 for a portable computer
`illustrated herein is generally of conventional design With
`the exception that it is designed to completely contain the
`internal poWer supply module 38 therein. Preferably, the
`poWer supply module 38 has mounts 40 integral thereWith so
`that it may be secured Within the main chassis portion 36.
`The poWer supply module 38 is at least partially surrounded
`by a module electromagnetic shield 42. The poWer supply
`module 38 is extremely light-Weight and has a miniaturiZed
`siZe and construction that alloWs it to be completely con
`tained Within the portable computer chassis 36. These dis
`tinct advantages reduce the bulkiness and the Weight asso
`ciated With conventional adapter devices. Moreover,
`because the poWer supply module 38 is secured Within the
`portable computer chassis 36, the user does not have to
`handle a heavy, cumbersome brick external poWer supply
`equipped With one or more detachable cords, but can
`instead, fully utiliZe the poWer supply module 38 simply by
`plugging a cord into it and an appropriate poWer source.
`Associated With the poWer supply module 38 is a poWer
`cord 44 that has a ?rst end 46 designed to be electrically
`connected to a conventional external poWer supply outlet of
`at least 100 volts and at least 50 cycles, and a second end 48
`designed to be connected directly to a line poWer input 50 of
`the poWer supply module 38. Preferably, the line poWer cord
`44 is an electrical cord that is adapted to be connected to
`conventional outlets found throughout most nations in the
`World. More preferably, hoWever, the line poWer cord 44 is
`adapted to be connected to a 110 volt, 60 cycle outlet. The
`poWer supply module 38 also preferably includes a moth
`erboard connector 52 that enables the poWer supply module
`38 to be removably connected directly to a motherboard 54
`positioned Within the portable computer chassis 36.
`Referring next to FIG. 3, illustrated is a second perspec
`tive vieW of the portable computer chassis 36 of FIG. 2 taken
`from the rear side thereof and With the poWer supply module
`38 exploded therefrom for clarity. In this vieW, the module
`electromagnetic shield 42 of the poWer supply module 38 is
`clearly illustrated. As seen in this preferred embodiment, the
`module electromagnetic shield 42 partially surrounds a
`circuit board and/or other electrical components (not shoWn)
`of th