United States Patent [19J
`Hahn et al.
`
`[54] UNIVERSAL LINEAR POWER SUPPLY
`
`[75]
`
`Inventors: Stan S. Hahn, Moraga; Sung Kee
`Baek, Martinez, both of Calif.
`
`[73] Assignee: Advanced Mobile Solutions, Inc.,
`Moraga, Calif.
`
`[21] Appl. No.: 08/963,701
`
`[22] Filed:
`
`Nov. 4, 1997
`
`Related U.S. Application Data
`
`[ 63] Continuation-in-part of application No. 08/670,247, Jun. 19,
`1996, Pat. No. 5,684,689.
`Int. Cl.6
`...................................................... H02M 1/00
`[51]
`[52] U.S. Cl. ........................... 363/146; 363/143; 439/131
`[58] Field of Search ..................................... 363/141, 142,
`363/143, 144, 145, 146; 439/131, 172
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`3,851,182 11/1974 Wallce ...................................... 307/23
`4,543,624
`9/1985 Rumble ................................... 363/146
`4,890,217 12/1989 Conway .................................. 363/143
`5,001,623
`3/1991 Magid ..................................... 363/143
`5,159,545 10/1992 Lee .......................................... 363/146
`5,726,875
`3/1998 Hirabayshi et al. .................... 363/142
`
`I lllll llllllll Ill lllll lllll lllll lllll lllll 111111111111111111111111111111111
`US005973948A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,973,948
`Oct. 26, 1999
`
`Primary Examiner-Peter S. Wong
`Assistant Examiner---Rajnikant B. Patel
`Attorney, Agent, or Firm-Nathan P. Koenig; Crosby,
`Heafey, Roach & May
`
`[57]
`
`ABSTRACT
`
`A universal linear power supply capable of automatically
`supplying a regulated DC current output from a range of AC
`input. In one preferred embodiment, interchangeable modu(cid:173)
`lar electrical plugs configured to mate with standard AC
`supplies releasably connect with the power supply. The
`power supply circuitry comprises a two-winding step-down
`transformer, a rectifier and a DC/DC step-down buck con(cid:173)
`verter. A projection on selected electrical plugs mechanically
`engages a switch on the power supply, connecting the
`primary coils of the transformer either in series or in parallel
`to accommodate 110 VAC or 220 VAC input. In another
`preferred embodiment, the invention comprises an electrical
`plug for accessing VAC input connected, releasably or
`permanently, to a power supply comprising a linear
`transformer, a full-wave rectifier and a DC/DC step-down
`forward converter which is capable of accommodating the
`full range of standard AC voltage. The interchangeable plugs
`may further comprise a releasable locking means mechani(cid:173)
`cally connected to the casing and designed to engage the
`electrical plug to maintain the plug in an operative position.
`
`8 Claims, 7 Drawing Sheets
`
`LGE-1007 / Page 1 of 11
`LGE v. Fundamental
`
`

`

`U.S. Patent
`
`Oct. 26, 1999
`
`Sheet 1 of 7
`
`5,973,948
`
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`LGE-1007 / Page 2 of 11
`
`

`

`U.S. Patent
`
`Oct. 26, 1999
`
`Sheet 2 of 7
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`5,973,948
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`LGE-1007 / Page 3 of 11
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`

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`U.S. Patent
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`Oct. 26, 1999
`Oct. 26, 1999
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`LGE-1007 / Page 4 of 11
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`Oct. 26, 1999
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`Oct. 26, 1999
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`LGE-1007 / Page 8 of 11
`
`

`

`5,973,948
`
`1
`UNIVERSAL LINEAR POWER SUPPLY
`
`RELATION TO OTHER APPLICATIONS
`
`This application is a continuation-in-part of Ser. No.
`08/670,247 filed Jun. 19, 1996, now U.S. Patent No. 5,684,
`689, which is hereby incorporated in its entirety by refer(cid:173)
`ence.
`
`BACKGROUND OF THE INVENTION
`
`20
`
`2
`Another approach to accommodating multiple physical
`outlet configurations on a single device is to integrate an
`interchangeable plug apparatus into the device which allows
`for easy alteration of the device/outlet compatibility without
`5 compromising the device physical characteristics as outlined
`above. A number of improvements in the art of interchange(cid:173)
`able plug design are disclosed in U.S. patent application Ser.
`Nos. 08/233,125, filed Apr. 26, 1994, 08/414,209, filed Mar.
`30, 1995, and 29/044,048, filed Sep. 15, 1995, incorporated
`10 herein in their entireties by reference.
`Both the adaptor and interchangeable plug approaches to
`solving the regional differences in outlet configuration fail to
`address the need to adjust the device electrical circuitry for
`compatibility with the output voltage associated with each
`15 particular source outlet configuration. Some power supply
`and electrical device manufacturers have addressed this
`issue by including an input supply adjustment switch on the
`device or power supply. However, failure to properly adjust
`such a switch before connecting to the outlet could damage
`the device, endanger the user and lead to a failure of the
`electrical circuit connected to the utilized outlet.
`Parent application Ser. No. 08/670,247 represents a fur(cid:173)
`ther refinement in this area. It discloses a system of inter(cid:173)
`changeable plugs that automatically accommodate the
`25 source voltage. This design does require, however, that each
`plug have an internal wiring configuration appropriate to
`connect the source voltage with the power supply's trans(cid:173)
`former coils in order to achieve the correct conversion.
`Moreover, such interchangeable plugs may be used only
`30 with this power supply and conversely, interchangeable
`plugs designed for other power supplies will not work.
`Finally, this system requires a three-winding step-down
`transformer to accommodate the wiring of the interchange(cid:173)
`able plugs.
`Accordingly, there remains a need for a simplified uni(cid:173)
`versal power supply that automatically adjusts to the source
`voltage and provides a regulated DC output of the desired
`voltage. There is also a need for such a power supply which
`can utilize low cost two-winding step down transformers
`and readily interchangeable plugs that do not require internal
`wiring. This invention satisfies these and other needs.
`
`People rely heavily on a wide variety of electrical devices.
`Almost all of these devices draw power ultimately from a
`national standard source, usually delivered to the user
`through a wall outlet or socket. This leads to a challenge for
`the manufacturer of electrical devices destined for interna(cid:173)
`tional use: while many electrical devices are sold for use
`throughout the world, there is no world standard for elec(cid:173)
`trical plug configurations, size, shape, voltage or number of
`prongs. The wide variety of socket configurations in use
`worldwide burdens international suppliers of mobile prod-
`ucts to varied countries and international travelers who wish
`to use electrical devices in a portable fashion. Moreover,
`different areas of the world use different voltage output
`standards. For example, in Europe and the U.K., the standard
`is 220 VAC, while in the U.S. the standard is 110 VAC.
`Most industrial nations use a standardized alternating
`current supply with only two leads, a hot side and a neutral
`side. Some outlets specifically incorporate a separate earth
`or ground lead while others do not. A problem exists,
`therefore, with physically accessing an AC current source
`supplied through any number of outlet configurations and
`interfacing that current source with the appropriate input
`connections for a power supply or other electrical device.
`The traditional solution for the mechanical prong con(cid:173)
`figuration problem is to provide an adapter which includes
`a socket to accommodate the prongs of the electrical device
`integrated with a second set of prongs in a configuration for
`a local socket. These adapters have some serious flaws. One
`problem is that the adapters are bulky and at a minimum,
`cause the prongs of the original device to be extended by at 40
`least the length of the additional set of prongs. Since most
`plug devices are designed to be secured by spring tension
`and interaction with a wall plug, this can pose a significant
`mechanical disadvantage. The increased lever arm created
`by the additional prong length will tend to shift the plug 45
`downward, tending to pry the plug out of the wall socket.
`This will be true even for a light-weight plug.
`The lever arm problem is accentuated with devices that
`are larger than a simple plug. Many power supplies and other
`electrical devices are designed to be wall-mounted at a wall
`socket. A typical power supply includes a casing which
`terminates in a plug designed to plug directly into the wall
`socket. The casing is often designed to lie against a wall to
`provide mechanical stability and to maintain the plug prongs
`in proper contact with the wall socket. If an adapter must be
`used, the unit loses the stability of resting against the wall
`and, because even a small amount of weight at the end of a
`lever arm will create a torque which will tend to pry the
`prongs out of the wall socket, such a plug adapter is
`generally unusable for such wall-mounted plug-in devices.
`Moreover, angling the plug severely can compromise the
`electrical connection to the point that the plug no longer is
`in electrical contact with source current. This type of angling
`may lead to partial separation from the wall socket and may
`expose the prongs of the plug in such a way that a person or
`animal might come into contact with live current, thereby
`causing bodily harm.
`
`35
`
`SUMMARY OF THE INVENTION
`
`One embodiment of his invention comprises an inter-
`changeable plug power supply including a casing, an elec(cid:173)
`trical plug detachably mounted in the casing and movable
`between a detached and an engaged, operative position, and
`a power supply configured to provide a regulated DC output.
`50 The power supply comprises a two-winding step-down
`transformer, a rectifier and a DC/DC step-down buck con(cid:173)
`verter. Preferably, selected electrical plugs further comprises
`a projection configured to mechanically engage a switch on
`the power supply casing to adapt the circuitry to 110 VAC
`55 or 220 VAC input. In another embodiment, the invention
`comprises an electrical plug for accessing AC input
`connected, releasably or permanently, to a power supply
`comprising a linear transformer, a full-wave rectifier and a
`DC/DC step-down forward converter and is capable of
`60 accommodating the full range of standard AC voltage with(cid:173)
`out the necessity of a mechanical switch. Yet another pre(cid:173)
`ferred feature comprises a releasable locking means
`mechanically connected to the casing and designed to
`engage the electrical plug to maintain the plug in an opera-
`65 tive position. The locking means can be released by a user
`to allow the plug to be moved to the detached position. A
`preferred form of locking mechanism is a depressible lock
`
`LGE-1007 / Page 9 of 11
`
`

`

`5,973,948
`
`3
`bar which is designed to engage a detent in the plug. The
`depressible lock bar is connected to or integral with the
`casing.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The aforementioned advantages of the invention, as well
`as additional advantages thereof, will be more fully under(cid:173)
`stood as a result of a detailed description of the preferred
`embodiment when taken in conjunction with the accompa(cid:173)
`nying drawings in which:
`FIG. 1, comprising FIGS. lA, lB, lC, lD and lE,
`illustrates perspective views of illustrative interchangeable
`plugs of the present invention and showing several inter(cid:173)
`changeable plugs usable in the inventive power supply
`device.
`FIG. 2 illustrates a perspective view of the inventive
`power supply device, including an interchangeable plug
`with automatic voltage selection feature, showing a repre(cid:173)
`sentative interchangeable plug in an operative position.
`FIG. 3, comprising FIGS. 3A and 3B illustrates a cross(cid:173)
`section of the device, showing a removable plug body and
`carrier ready to be connected to the device (FIG. 3A) and
`connected (FIG. 3B).
`FIG. 4 is a block diagram of the power supply wiring of 25
`a preferred embodiment of the invention including a sche(cid:173)
`matic of the switching mechanism for discriminating
`between source voltages for a preferred embodiment of the
`invention.
`FIG. 5 is an exemplary circuit diagram of the power
`supply for the embodiment of the invention shown in FIG.
`4.
`
`4
`a preferred embodiment of the inventive device in an
`operative position integrated with the casing. Casing 1
`includes various features to support and position various
`components of the device. Plug 13 is a generally rectangular
`5 element with a centered tongue 14. Detent 15, shown in
`greater detail in FIGS. lA-lD, is integral with tongue 14.
`FIGS. 3A and 3B show lock bar 22 deformably positioned
`within casing 1. Lock bar 22 is made of a suitable material,
`such as a plastic material, which is resilient, tends to return
`10 to a preferred position, and can be secured at one end and be
`bent repeatedly to perform the needed release function yet
`return to a resting position with enough tension to perform
`the needed latch function. Lock bar 22 is preferably formed
`integral with casing 1. Release button 20 is connected to or
`15 preferably integral with lock bar 22. Lock bar 22 is designed
`to engage detent 15. Detent 15 is shaped to accommodate the
`configuration of lock bar 22.
`When a plug 13 and casing 1 are integrated into a singular
`unit, lock bar 22 is pressed against detent 15 by the natural
`20 tension and resilience of lock bar 22. To release the plug 13
`from the casing 1, release button 20 is depressed, which
`moves lock bar 22 away from casing 1 and from detent 15.
`Plug 13 can then be disengaged from casing 1.
`The pressure of lock bar 22 against detent 15 will main-
`tain each plug 13 in the operative position until a user
`activates release button 20, moving it from a resting position
`to a released (depressed) position as shown in FIG. 3 B. Once
`the release button is moved and lock bar 22 is removed from
`30 detent 15 at least far enough so that the plug 13 can slide
`freely, the user can move plug 13 away from casing 1.
`Although conducting sleeves 16 may remain hot electrical
`leads after plug 13 is removed, a user or passerby is
`protected from inadvertent contact with the conducting pins
`35 by their submerged position relative to the plug 13.
`FIG. 4 schematically illustrates the power supply wiring
`of one preferred embodiment of the invention. Transformer
`40 is fed current from the wall outlet (not shown) through a
`springloaded, momentary double-pole double-throw
`40 (DPDT) switch 42 which engages the primary coils 44 of the
`transformer either in series or in parallel. Output from
`transformer 40 is then rectified 46 and fed to DC/DC
`step-down buck converter 48 which produces a constant
`voltage DC output. FIG. 5 shows an exemplary circuit
`45 diagram suitable for use in this embodiment of the invention.
`Plug 13 configured for use with a 110 VAC supply (FIG. lC)
`further comprises a projection 17, configured to engage
`switch 42. As shown in FIG. 4, when switch 42 is not
`engaged by projection 17 on plug 13, switch 42 connects
`50 primary coils 44 in series to accommodate a 220 VAC
`supply. When switch 42 is engaged by projection 17 on plug
`13, it connects primary coils 44 in parallel to accommodate
`a 110 VAC supply. This configuration prevents overload and
`damage if a 110 VAC plug is used that does not engage the
`55 switch. In other embodiments, switch 42 could also activate
`a conventional voltage detection and cutoff circuit. Such a
`circuit would detect voltages in significant excess of 110
`VAC to safeguard against switch 42 getting stuck in the
`engaged position.
`In another embodiment, shown as a block diagram in FIG.
`6, a power supply circuit which can accommodate 110 VAC
`or 220 VAC without mechanical switching may be
`employed. The goal of such a circuit is to provide low-cost
`power supply capable of automatically accommodating
`65 input ranging from 90 to 264 VAC. Existing linear power
`supplies generally provide a constant DC output only when
`supplied current in relatively narrow ranges: either 105 to
`
`60
`
`FIG. 6 is a block diagram of the power supply wiring of
`another preferred embodiment of the invention.
`FIG. 7 is a circuit diagram of the power supply for the
`embodiment of the invention shown in FIG. 6.
`
`DETAILED DESCRIPTION OF A PREFERRED
`EMBODIMENT
`
`A preferred embodiment of the present invention includes
`a casing, a plug mounted to the casing, a locking device to
`secure the mounted plug, and a power supply capable of
`accommodating a wide range of source voltage while pro(cid:173)
`viding a linear regulated DC output.
`Referring to FIGS. lA, lB, lC, lD and lE, casing 1
`includes cavity 2 with channel 28 which is designed to
`accommodate any one of the plugs 13 depicted in the figures
`with tongue 14. FIG. 1 B illustrates a plug designed for the
`United Kingdom, FIG. lC for the United States, FIG. lD for
`Europe and FIG. lE for Australia. A plug 13 configured for
`use with 110 VAC supply may preferably include a projec(cid:173)
`tion 17 configured to engage a switch 42 housed in casing 1.
`Plug characteristics for other countries such as South Korea,
`can easily be integrated into the present invention. Sockets
`3 with conductors 25, are designed to accommodate con(cid:173)
`ducting members 16 of plugs 13 (see FIGS. lA-lD). In a
`preferred embodiment, casing 1 is preferably made of high
`impact thermoplastic material, with top and bottom halves
`which can be sealed together by ultrasonic bonding.
`In one embodiment, shown in FIG. lA, power supply 7,
`preferably a linear power supply (FIGS. 5 and 7) contained
`on a printed circuit board, receives input power from con(cid:173)
`ducting pins 25. Power supply 7 selectively forwards DC
`power through electrical cable 19 to electronic device 8.
`FIG. 2 provides an isometric profile and FIG. 3B illus(cid:173)
`trates a cutaway view of the interchangeable plug feature of
`
`LGE-1007 / Page 10 of 11
`
`

`

`5,973,948
`
`5
`128.7 VAC or 210 to 257.4 VAC. Such power supplies are
`inadequate in view of the standard ranges of 90 to 132 VAC
`and 180 to 264 VAC encountered internationally.
`Thus, this embodiment of the invention comprises linear
`transformer 50 feeding rectifier 52 which then supplies DC 5
`current to forward converter 54 which produces regulated
`DC output at the desired voltage. Preferably, linear trans(cid:173)
`former 50 steps down the AC input by a factor of 10 to
`produce AC output of about 9 to 26.4 VAC. Full-wave
`rectifier 52 then converts this to DC current of the same
`range. Finally, DC/DC step down forward converter 54
`produces regulated DC output of the desired voltage. An
`exemplary circuit diagram suitable for this embodiment of
`the invention is shown in FIG. 7. Thus, in this embodiment,
`any AC input in the range of 90 to 264 VAC may be used to
`produce a low-voltage regulated DC output of up to about 15
`watts.
`A number of additional features of the interchangeable
`plug element of the present invention are disclosed in
`copending U.S. patent application Ser. Nos. 08/233,125,
`filed Apr. 26, 1994, 08/414,209, filed Mar. 30, 1995, and
`08/670,247, filed Jun. 19, 1996 already incorporated by
`reference.
`A general description of the device and method of using 25
`the present invention as well as a preferred embodiment of
`the present invention has been set forth above. One skilled
`in the art will recognize and be able to practice many
`changes in many aspects of the device and method described
`above, including variations which fall within the teachings 30
`of this invention. The spirit and scope of the invention
`should be limited only as set forth in the appended claims
`and their equivalents.
`What is claimed is:
`1. An AC universal power conversion apparatus compris- 35
`ing:
`a plurality of electrical plugs each having a pin configu(cid:173)
`ration suitable for compatible connection to a selected
`AC line having a different standard voltage wherein a
`first electrical plug further comprises a projection; and 40
`a casing for releasably receiving the electrical plugs,
`comprising power supply circuitry, connectors for pro(cid:173)
`viding an electrical connection between the electrical
`plug and the power supply circuitry, and a switch
`having a first and second position which is configured
`
`6
`to be engaged by the projection on the first electrical
`plug; wherein the power supply circuitry comprises a
`transformer having primary coils, a rectifier and a
`DC/DC step-down buck converter such that the pri-
`mary coils are connected to the electrical plug in series
`when the switch is in the first position and the primary
`coils are connected to the electrical plug in parallel
`when the switch is in the second position.
`2. The universal power supply apparatus of claim 1,
`10 comprising two electrical plugs wherein the first electrical
`plug is configured to connect with a standard 110 VAC
`supply and a second electrical plug is configured to connect
`with a standard 220 VAC supply.
`3. The universal power supply apparatus of claim 2,
`15 wherein the projection of the first electrical plug engages the
`switch, placing the switch in the second position.
`4. The universal power supply apparatus of claim 1,
`wherein the power supply circuitry produces a regulated DC
`output when the electrical plug is connected to a AC supply
`20 having a range of 90 to 132 VAC or 180 to 264 VAC.
`5. The universal power supply apparatus of claim 1,
`wherein the power supply circuitry further comprises a
`voltage detection and cutoff subcircuit connected to the
`transformer.
`6. A universal power supply apparatus comprising:
`an electrical plug having a pin configuration suitable for
`compatible connection to a selected AC line having a
`standard voltage; and
`power supply circuitry connected to the electrical plug
`and comprising in sequence a linear transformer, a
`full-wave rectifier and a regulating DC/DC step-down
`forward converter,
`wherein the power supply circuitry produces a regulated
`DC current output when the electrical plug is connected
`to an AC line having a voltage with a range from about
`90 VAC to about 264 VAC.
`7. The universal power supply of claim 6 wherein the
`electrical plug is releasably connected to the power supply
`circuitry.
`8. The universal power supply of claim 7, further com(cid:173)
`prising a plurality of electrical plugs, each electrical plug
`having a pin configuration suitable for compatible connec(cid:173)
`tion to a different AC line.
`
`* * * * *
`
`LGE-1007 / Page 11 of 11
`
`