United States Patent
`Sakamoto etal.
`
`i159)
`
`[11] Patent Number:
`
`[45] Date of Patent:
`
`4,873,677
`Oct. 10, 1989
`
`[54] CHARGING APPARATUS FOR AN
`ELECTRONIC DEVICE
`
`[75]
`
`Inventors:
`
`Kenji Sakamoto; Nobuo Ishikawa;
`Motomu Hayakawa, all of Suwa,
`Japan
`
`FOREIGN PATENT DOCUMENTS
`
`1027143
`53-82473
`60-174976
`336027
`
`3/1958 Fed. Rep. of Germany...... 368/204
`7/1978 Japanr ....ssessssssesessssssssssresesese 368/203
`
`9/1985 Japan..........
`3/1959 Switzerland... 368/204
`
`[73] Assignee:
`
`Seiko Epson Corporation, Tokyo,
`Japan
`
`Primary Examiner—Vit W. Miska
`Attorney, Agent, or Firm—Blum Kaplan
`
`[21] Appl. No.: 216,914
`
`[22] Filed:
`
`Jul. 7, 1988
`
`Foreign Application Priority Data
`[30]
`Jul. 10, 1987 [JP]
`Japan o...cessssesesccecsssscenss 62-106457[U]
`Japan wescssessssssssesssessesscecee 62-176399
`Jul. 15, 1987 [JP]
`
`
`JAPAand .cccscsscssecrecneerssrenenee 62-176400
`Jul. 15, 1987 [JP]
`Japar wsesssssssssssssssscscesesesese 62-176401
`Jul. 15, 1987 [JP]
`
`“Int. C14 occ eeeeeeeeee GO04C 10/04; HO1M 10/44
`[51]
`
`[52] U.S. C1. wees
`esctesetetcteteresceeeeeeeee 368/204; 320/2;
`320/61
`[58] Field of Search.................... 368/64, 66, 203-205;
`320/2, 21, 61
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4,371,269 2/1983 Sutter 0...eesessneseneeeeee. 368/205
`4,644,246 2/1987 Knaden .......cssctcsnsteorereseees 320/21
`
`ABSTRACT
`[57]
`An apparatus for charging a power storage device pro-
`vided within an electronic device. A power source
`provides direct current whichis alternated in direction
`through a pair of primary coils for inducing alternating
`current in a secondarycoil of the electronic device. The
`pair of primary coils are fixed to a coil yoke all of which
`are supported within a casing of the apparatus. During
`charging of the power storage device, the electronic
`device is mounted to the outside surface of the casing
`whereby substantially all of the magnetic flux of the
`magnetic field produced by the pair of primary coils
`flows through the secondary coil and coil yoke. The
`frequency ofthe oscillating signal is preset to provide
`the maximum induced current which will not adversely
`affect the movementof the analog mechanisms within
`the electronic device.
`
`1
`
`Apple v. GUI
`IPR2021-00472
`
`36 Claims, 6 Drawing Sheets APPLE 1071
`
`1
`
`APPLE 1071
`Apple v. GUI
`IPR2021-00472
`
`

`

`U.S. Patent
`
`Oct. 10, 1989
`
`Sheet 1 of6
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`4,873,677
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`51[yy622
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`tl
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`Sot
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`SISAIOSA#PPLMOS
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`US. Patent—Oct. 10, 1989 Sheet 2 of 6
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`4,873,677
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`US. Patent—Oct. 10, 1989 Sheet3 of6 4,873,677
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`
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`SWITCH 107
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`|
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`FIG.4
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`‘Vtim
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`Ve
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`4
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`US. Patent—Oct.10, 1989 Sheet 4 of6 4,873,677
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`
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`FIG. 6
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`
`
`fnertiamoment
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`Rotor
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`[4
`(¢2,5mn)
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`I3
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`L5
`(¢3,0m
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`($2.0mm
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`0
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`100
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`200
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`300
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`400
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`500
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`600
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`Maximum freg uency Hz
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`US. Patent—Oct. 10, 1989 Sheet5 of 6 4,873,677
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`
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`FIG. 7
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`— 2.
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`;
`
`&
`e
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`S/
`s
`of
`/
`8 900
`/
`. 2
`i
`8
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`\
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`\
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`.
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`*
`\
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`G00
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`ot
`500 600 700 800 900 1000 100 /200 300 7400 1500
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`Freg uency f (Hz)
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`6
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`US. Patent—Oct.10, 1989 Sheet 6 of6
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`4,873,677
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`7
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`1
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`4,873,677
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`CHARGING APPARATUS FOR AN ELECTRONIC
`DEVICE
`
`BACKGROUNDOF THE INVENTION
`
`5
`
`2
`charging of the wristwatch. Unfortunately, an undesir-
`able image of the watch is created due to hand move-
`ment being halted during the charging period. The
`magnetic field also adversely affects any other analog
`timepiece positioned near the window display of the
`charging device.
`It is therefore desirable to provide a charging device
`for an electronic timepiece such as a wristwatch which
`is relatively small in size, inexpensive to manufacture
`and which charges the battery of the wristwatch in a
`relatively short period of time. The charging device
`should also consume relatively little energy and in-
`crease the efficiency in transferring energy to the bat-
`tery of the wristwatch compared to charging devices
`presently commercially available.
`SUMMARYOF THE INVENTION
`
`This invention relates to a charging apparatus, and
`more particularly to a charging apparatus for use with
`an electronic device.
`Different charging apparatuses for charging an elec-
`tronic device such as, but not limited to, an analog
`electronic timepiece, are presently available. Generally,
`light or electromanetic energy from or a direct connec-
`tion to an external power source is used to recharge a
`battery within the timepiece.
`,
`A typical charging apparatus employing light energy
`includes a solar battery as part of a dial plate of the
`timepiece. The solar battery generates electric power
`for charging a secondary battery located within the
`in accordance with the inven-
`Generally speaking,
`tion, a charging apparatus for charging a powerstorage
`timepiece.
`A charging apparatus employing a direct connection
`device in an electronic device includes a power source
`to an external powersourceis disclosed within Japanese
`for producing direct current and a pair of primary coils.
`Patent Laid-Open Application Nos. 154665/77 and
`The primary coils are connected electrically in series
`11846/74 and Japanese Utility Model Publication No.
`and generate an alternating magnetic field which passes
`4240/81. The battery located within the timepiece is
`through a secondary coil located within the electronic
`charged by connecting a lead between the external
`device. The alternating magnetic field inducesalternat-
`power source and a terminal located on the external
`ing current in the secondary coil which is rectified to
`surface of the timepiece.
`charge the power storage device.
`A charging apparatus for transferring electromag-
`The charging apparatusalso includes a coil yoke for
`netic energy from an external sourceto the timepieceis
`positioning the primary coils relative to each other and
`disclosed in Japanese Patent Laid-Open Application
`an oscillating circuit for generating an oscillating signal.
`No. 29783/86. The source of electromagnetic energy is
`Switching circuitry within the charging apparatusalter-
`coupled to a charging coil disposed within the time-
`natesthe direction of the direct current flowing through
`piece which induces a current for charging a battery
`the primary coils in response to the oscillating signal.
`also disposed within the timepiece. A counting coinci-
`A case memberof the charging apparatus includes a
`dencecircuit of the timepiece counts and thereby con-
`pair of fingers for receiving and holding the electronic
`trols the length of time during which the battery is
`device. The pair of primary coils and coil yoke are
`charged. The timepiece also includes a motor and a
`supported within the case memberat a predetermined
`motor driving circuit for regulating the motor. The
`distance relative to the fingers so that substantially all of
`motor driving circuit maintains the motor in a deener-
`the magnetic flux of the magnetic field flows through
`gized (i.e. OFF) state during the charging period. The
`the secondary. coil and the coil yoke resulting in the
`timepiece also includes compensating circuitry for cor-
`efficient coupling of energy to the electronic device.
`recting the time displayed by the timepiece for the
`In another embodiment,
`the oscillating circuit
`in-
`charging period when the motoris deenergized. Each
`cludes a variable resistor operable for changing the
`of these conventional charging apparatuses has one or
`constant of the oscillating circuit and.thereby adjusting
`more drawbacks. These drawbacks are particularly
`the frequency of the oscillating signal to a predeter-
`undesirable when the timepiece is an analog electronic
`mined level. The predetemined frequencylevelis set to
`wristwatch.
`avoid adversely affecting operation of a permanent
`Charging apparatuses employing a solar battery or a
`magnet rotor which is part of a motor located within
`direct connection from an external power source limit
`the electronic device. The motor is used to provide
`the variety of ornamental wristwatch designs which can
`power for moving the hands of the watch.
`be used. The limitation is due to the physically small
`The switching circuitry includes fourpairs of transis-
`size of the wristwatch. The difficulty in providing a
`tors connected electrically together to form a parailel
`variety of ornamental wristwatch designsis particularly
`circuit. Two of the four pairs oftransistors formafirst
`troublesome when the ornamental appearance is com-
`55
`branch of the parallel circuit. The second two pairs
`mercially significant.
`form a second branchof the parallel circuit. Each pair
`Charging apparatuses whichtransfer electromagnetic
`of transistors serves as a transistor switch, that is, each
`energy to a wristwatch as disclosed in Japanese Patent
`branchofthe parallel circuit has twotransistor switches
`Laid-Open Application No. 29783/86 adversely affect
`connected electrically in series. The pair of primary
`the movementof a step motorof the wristwatch result-
`coils are connected between the twotransistor switches
`ing in improper hand movementof the watch. Motor
`of the first parallel branch and the two transistor
`control circuitry, counting circuitry and circuitry (i.e.
`switches of the second parallel branch. By electrically
`consistent means) are required in the timepiece in order
`opening one transistor switch and closing the other
`to provide continuous and accurate hand movement
`transistor switch in each branchof the parallel circuit,
`during the charging period. Such circuitry limits the
`65
`current flows throughthepair of primarycoils inafirst
`variety of different ornamental wristwatch designs
`direction. By opening the transistor switches which
`available and increases the cost of manufacturing an
`were previously closed and closing the transistor
`analog electronic wristwatch. This type of charging
`switches which were previously opened, current flows
`device also can be used as a window display during
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`BRIEF DESCRIPTION OF THE DRAWINGS
`
`3
`throughthe pair of primarycoils in a direction opposite
`to the first direction. This generates an alternating mag-
`netic field in the primary coils.
`Accordingly, it is an object of the invention to pro-
`vide an improved charging apparatus which is rela-
`tively small in size and inexpensive to manufacture.
`It is another object of the invention to provide an
`improved charging apparatus which charges the battery
`of the electronic apparatus in a relatively short period of
`time while consumingrelatively little energy.
`It is a further object of the invention to provie an
`improved charging apparatus which efficiently trans-
`fers energy from the charging apparatus to the elec-
`tronic device.
`It is still another object of the invention to provide an
`improved charging apparatus which transfers electro-
`magnetic energy from a charging apparatus to an elec-
`tronic device without adversely affecting the operation
`of the electronic device during charging.
`Still other objects and advantages of the invention
`will in part be obvious and will in part be apparent from
`the specification.
`The invention accordingly comprises several steps in
`a relation of one or more of such steps with respect to
`each of the others, and the apparatus embodying fea-
`tures of construction, a combination of elements, and
`arrangements of parts which are adapted to effect such
`steps, all is exemplified in the following detailed disclo-
`sure and the scope of the invention will be indicated in
`the claims.
`
`4
`well knownoscillator using input hysterises of NAND
`gate 226 to produceoscillating signal SO. Signal SO is
`provided to an input 150 of a NAND gate 153. An
`output 156 of NANDgate 153 provides a signal S1 to
`the base ofa transistor 201 througha resistor R1, to the
`base of transistor 204 through a resistor R2 and to an
`input 159 of a NAND gate 162, An output 165 of
`NANDgate 162 provides a signal S2 to the base of a
`transistor 214 througha resistor R3 andto the base of a
`transistor 217 through a resistor R4. An input 151 of
`NANDgate 153 and an input 160 of NAND gate 162
`are connected together to an output 168 of a NAND
`gate 171. Output 168 of NAND gate 171 produces a
`signal OPR which is supplied to input 151 of NAND
`gate 153 and to input 160 of NANDgate 162. A first
`input 174 and a second input 177 of NANDgate 171 are
`connected together, to a terminal 180 of a switch 107
`and to an output 183 of a timer 108. A second terminal
`186 of switch 107 is connected to the commonreference
`voltage level such as ground. The voltage potential
`across switch 107 is denoted by voltage Vtim. An input
`189 of timer 108 is connected to a d.c. power source
`110. Timer 108 also includes a resistor R13 and a capaci-
`tor C2. With switch 107 closed, capacitor C2 of timer
`108 charges to the voltage level of d.c. power source
`110 and voltage Vtim is at a logic level of0.
`Output 168 of NAND gate 171 is also connected to
`the base of a transistor 192 through a resistor R5. The
`emitter of transistor 192 is connected to the base of a
`transistor 195 and to the emitter of transistor 195
`through a resistor R6. The collectors of transistors 192
`and 195 are connected together to one end of a resistor
`R7. Transistors 192 and 195 and resistor R6 are com-
`Fora fuller understanding of the invention, reference
`monly referred to as a Darlington amplifier and provide
`is had to the following description taken in connection
`a high current gain. The other end of resistor R7 is
`with the accompanying drawings, in which:
`connected to one end of a LED 109. The other end of
`FIG.1 is a circuit schematic of a charging device in
`LED109 is connected to d.c. power source 110 through
`accordance with the invention;
`anode 198. The emitter oftransistor 195 is connected to
`FIG. 2 is a perspective view of a pair of charging
`the commonreference voltage level such as ground.
`coils of a charging device of the type shownin FIG.1;
`Thecollector of a transistor 207 is connected to the
`FIG. 3 is a perspective view of a pair of charging
`coils in accordance with an alternative embodiment of
`collector of transistor 201. The emitter of transistor 201
`is connected to the base of transistor 207 and to the
`the invention;
`emitter of transistor 207 through a resistor R8. Transis-
`FIG. 4 is a timing chart illustrating the signals pro-
`tors 201 and 207 and resistor R8 form a Darlington
`duced within the circuit schematic of FIG.1;
`amplifier which serves as a transistor switch 102.
`FIG.5 is a diagrammatic view of the charging device
`The collector of a transistor 210 is connected to the
`and an analog electronic wristwatch;
`collector of transistor 204. The emitter of transistor 204
`FIG.6 is a plot of rotor inertia momentof the wrist-
`is connected to the base of transistor 210 and to the
`watch vs. frequency of the alternating magnetic field
`emitter of transistor 210 through a resistor R9. The
`producedbyapair of charging coils;
`emitter of transistor 210 is connected to the common
`FIG.7 is a plot of induced current flowing through a
`reference voltage such as ground. Transistors 204 and
`secondary coil of the watch vs. frequency of the alter-
`210 and resistor R9 form a Darlington amplifier which
`nating magnetic field produced by the chargingcoils;
`serves as a transistor switch 104.
`FIG. 8 is a perspective view of a wristwatch mounted
`The collector of transistor 214 is connected to the
`on a charging device in accordance with the invention;
`and
`coliector of a transistor 220. The base of transistor 220
`is connected to the emitter of transistor 214. The emitter
`FIG.9 is a sectional view taken along lines 9—9 of
`FIG.8.
`of transistor 220 is connected to the emitter of transistor
`214 through a resistor R10. Emitters of transistors 220
`and 207 are also connected to d.c. power source 110
`through node 198. Transistors 214 and 220 and resistor
`R10 form a Darlington amplifier and act together as a
`transistor switch 103.
`The collector of transistor 217 is connected to the
`collector of a transistor 223. The base oftransistor 223
`is connected to the emitter of transistor 217. The emitter
`of transistor 223 is also connected to the emitter of
`transistor 217 through a resistor R11. The emitter of
`transistor 223 is connected to the common reference
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`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`FIG. 1 illustrates a charging device 100 which in-
`cludes an oscillator 101 for producing an output signal
`$0. Oscillator 101 includes a Schmidtt trigger NADD
`gate 226, a variable resistor R12 connected between the
`inputs and output of Schmidtt trigger NAND gate 226
`and a capacitor C1 connected between the inputs of
`Schmidtt trigger NAND gate 226 and a commonrefer-
`ence voltage level such as ground. Oscillator 101 is a
`
`9
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`

`5
`voltage such as ground. Transistors 217 and 223 and
`resistor R11 form a Darlington amplifier and act to-
`getheras a transistor switch 105.
`A pair of charging coils 106 and 106’ are connected
`electrically in series. An end 111 of charging coil 106 is
`connected to the collectors of transistors 201, 204, 207
`and 210 (i.e. between transistor switches 102 and 104).
`An end 111’ of charging coil 106’ is connected to the
`collectors of transistors 214, 217, 220 and 223 (i.e. be-
`tween transistor switches 103 and 105).
`Referring now to FIGS. 1 and 4, the charging opera-
`tion of an analog electronic watch 117 (shown in FIG.
`5) is begun by opening switch 107 once capacitor C2 has
`been fully charged to the level of d.c. power source 110.
`Capacitor C2 begins to charge through resistor R13.
`Voltage Vtim gradually rises from a logic level of 0 to
`above a level of voltage V; which represents the mini-
`mum value of a logic level equal to 1. The rise in volt-
`age Vtim is based on the RC time constantof timer 108
`(ie. the product of the resistance of resistor R13and
`capacitance of capacitor C2). Prior to voltage Vtim
`reaching level V;, signal OPRis at a high logic level of
`1. While signal OPRis at a high logic level of 1 alternat-
`ing current flows through charging coils 106 and 106’ as
`described below. Simultaneously,
`transistor 192 is
`turned on so that current flows through LED 109 to
`indicatethat the charging operation is underway. Once
`voltage Vtim reaches the level of voltage V, the charg-
`ing operation ends. More particularly, with voltage
`Vtim at a logic level of 1, signal OPRis at a low logic
`level of 0. Signals S1 and S2 are at a high logic level of
`1 whichresults in transistor switches 104 and 105 being
`turned on. A pair of signals S3 and S4, which represent
`the voltages at ends 111 and 111’ of charging coils 106
`and 106’,
`respectively, are now at approximately
`ground potential. Since signals S3 and S4 are at the
`same voltage potential, no current flows through coils
`106 and 106’ (i.e. charging operation ends).
`During charging of wristwatch 117, the flow of cur-
`rent through charging coils 106 and 106’ alternate in
`opposite directions depending upon which of the four
`transistor switches 102, 103, 104 and 105 are closed.
`Moreparticularly, when transistor switches 102 and 105
`are closed (i.e. transistors 201, 207, 217 and 223 are
`turned on) and transistor switches 103 and 104 are
`opened(i.e. transistors 204, 210, 214 and 220 are turned
`off) current provided by d.c. power source 110 flows
`from end 111 of charging coil 106 to end 111’ of charg-
`ing coil 106’. When switches 103 and 104 are closed(i.e.
`transistors 204, 210, 214 and 220 are turned on) and
`switches 102 and 105 are opened (i.e. transistors 201,
`207, 217 and 223 are turned off) current flows from end
`111’ of charging coil 106’ to end 111 of charging coil
`106.
`As shown in FIG. 2 charging coils 106 and 106’ are
`coupled to a coil yoke 112. Coil yoke 112 is a substan-
`tially rectangular plate made from iron, permeable steel
`or a like material. Charging coils 106 and 106’ each have
`a substantially triangular ring-like contour. Charging
`coils 106 and 106’ are not limited to substantially triang-
`ular ring-like contours and may have other different
`configurations such as, but not limited to, cylindrical
`contours. Charging coils 106 and 106’ are shown in
`FIG. 1 connected electrically in series but also can be
`connected electrically in parallel.
`Uponapplying an alternating voltage across charging
`coils 106 and 106’, that is, across ends 111 and 111’ of
`chargingcoils 106 and 106’, respectively, an alternating
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`magnetic field is generated by charging coils 106 and
`106’. Charging coils 106 and 106’ are operated so that
`opposite polarities exist on an upper end 250 and an
`upper end 253 of charging coils 106 and 106’, respec-
`tively. In other words, when current flows through
`serially connected charging coils 106 and 106’ in a first
`direction, upper surface 250 of charging coil 106 has a N
`(i.e. north) polarity and upper surface 253 of charging
`coil 106’ has a S (i.e. south) polarity. When the current
`flowing through charging coils 106 and 106’ reverses
`direction, upper surface 250 of charging coil 106 has aS
`polarity and upper surface 253 of charging coil 106’ has
`a N polarity. The opposite polarities of upper surfaces
`250 and 253 of charging coils 106 and 106’, respectively,
`are obtained by winding charging coils 106 and 106’ in
`opposite directions and connecting the charging coils
`together electrically in series or otherwise connecting
`coils 106 and 106’ together so that the frontor rear sides
`of the respective coils lie in opposing adhering direc-
`tions (i.e. in directions which attract each other).
`The end opposite to end 111 of charging coil 106 and
`the end opposite to end 111’ of charging coil 106’ are
`electrically connected to each other. Ends 111 and 111’
`are drawn through openings 113 and 113’ of coil yoke
`112, respectively. A pair of openings 114 and 114’ of
`coil yoke 112 allow passage therethrough ofa pair of
`fixing screws 125 and 125’ (shownin FIG.9) to secure
`coil yoke 112 to a casing 123 (shown in FIG. 9) of
`charging device 100.
`As shownin FIG.3, charging coils. 106 and 106’ can
`be woundarounda pair of magnetic cores 115 and 115’,
`respectively. Each of the magnetic cores 115 and 115’
`are made from a malleable iron or other suitable mate-
`rial. Charging coils 106 and 106’ are secured to a sub-
`strate 116 of coil yoke 112. Substrate 116 is made from
`plastic, glass epoxyorthelike.
`Referring once again to FIG.4,thesignals at various
`points within the circuit of FIG.1 andpolarities ofcoils
`106 and 106’ are illustrated relative to each other. Signal
`SO producedbyoscillator 101 is a substantially square
`wave having a frequency f. By adjusting resistor R12
`which varies the constant of oscillator 101, frequency f
`of signal SO can be set to a predetermined value for
`charging wristwatch 117. The range of acceptable fre-
`quenciesis discussed in greater detail below. Signals S1
`and S2 produced by NANDgates 153 and 162, respec-
`tively, are 180 degrees out of phase with each other
`whensignal OPRis at a high logic level of 1. Signal $2
`is in phase with outputsignal SO ofoscillator 101 when
`signal OPRat a high logic level of 1 (i.e. signals SO and
`S1 are 180 degrees out of phase with each other). Sig-
`nals S3 and S4 are 180 degrees out of phase with each
`other, signals $2 and S3 are in phase with each other
`and signals S1 and S4 are in phase with each other when
`signal OPR at a high logic level of 1. The flow of cur-
`rent through charging coils 111 and 111’ alternate in
`direction based on frequency f, that is, the frequencies
`of S3 and S4 are determined by frequencyf of signal SO
`whensignal OPRis at a high logic level of 1. A pair of
`polarities P1 and P2 represent the directions of the
`magnetic polarities formed on upper ends 250 and 253
`of coils 106 and 106’, respectively. Polarities P1 and P2
`are 180 degrees out of phase with each other.
`The construction of charging device 100 has been
`described based on the circuitry shown in FIG. 1. It is
`to be understood, however, that charging device 100
`can be constructed using other circuitry which provides
`alternating current flow through coils 106 and 106’. For
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`4,873,677
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`7
`example, an oscillating circuit using quartz oscillators
`and ceramicoscillating circuits can be employedin lieu
`of oscillator 101. Charging device 100 also has been
`disclosed heretofore with oscillator 101 operating dur-
`ing charging and noncharging periods of operation. If
`desired, timer 108 can be coupled to oscillator 101 so
`that signal SO is generated only during charging peri-
`ods.
`As shown in FIG. 5, analog electronic wristwatch
`117 includes a coil 118 having a core 119 and connected
`to a rectifying circuit 120 which includes a diode 141. A
`battery 121, which serves as the power source for wrist-
`watch 117, is connected in series with coil 118 of recti-
`fying circuit 120. During charging, wristwatch 117 is
`disposed near charging device 100 so that the magnetic
`flux from the magnetic field created by charging coils
`106 and 106’ passes through coil 118 of wristwatch 117.
`The magnetic circuit formed includes charging coils
`106 and 106’, coil 118, core 119 and coil yoke 142 with
`charging coil 106 and 106’ acting as a pair of primary
`coils and coil 118 acting as a secondary coil. The mag-
`netic flux alternates in directions denoted by arrows A
`and B. Consequently, magnetic flux 122 inducesa volt-
`age across coil 118 resulting in an induced current flow-
`ing through rectifying circuit 120 to charge battery 121.
`Wristwatch 117 also includes a step motor 180 having a
`stator 182 and a permanent magnet 183. Motor 180 is
`powered by battery 121 through coupling of stator 182
`to charging battery 121.
`Substantially all of magnetic flux 122 passes through
`coil yoke 112 due to charging coils 106 and 106’ being
`fixed to coil yoke 112. Coil yoke 112 aids in the concen-
`tration and direction of alternating magnetic flux 122 to
`provide an effective coupling of magnetic flux 122 to
`coil 118. Without coil yoke 112, the path of magnetic
`flux 122 would travel through air resulting in far less
`magnetic flux 122 passing through coil 118. A far less
`efficient coupling of magnetic flux between charging
`coils 106 and 106’ and coil 118 would result.
`Since charging coils 106 and 106’ have opposite po-
`larities relative to each other, the path of magnetic flux
`122 passes from surface 250 to coil 118 to surface 253
`when magnetic flux 122 flowsin the direction of arrow
`A and from surface 253 to coil 118 to surface 250 when
`magnetic flux 122 flows in the direction of arrow B. In
`contrast thereto, if the polarities of charging coils 106
`and 106’ were the same,thatis, the polarities of surfaces
`250 and 253 were the same, repulsion of a portion of
`magnetic flux 122 near coil 118 would occur. Less mag-
`netic flux would be coupled to coil 118 resulting in far
`less induced current charging battery 121 at any in-
`stance in time. In other words, a far less efficient cou-
`pling of magnetic flux and charging of battery 121
`would result.
`FIG.6 illustrates the inertia momentof rotor 183 vs.
`the maximum frequency of the magnetic field created
`by charging coils 106 and 106’. Rotor 183 does not
`operateat frequencies to the left of a line 300 (i.e. region
`I). Consequently, frequencies within region I will not
`adversely affect the movement of the hands of wrist-
`watch 117 or otherwise cause misoperation or undesir-
`able vibration or the like of wristwatch 117. Frequen-
`cies to the right of line 300 (i.e. region II) adversely
`affect rotor movement and should be avoided. The
`rotor inertia moments [1, I2, I3, 14 and I5 are. based on
`the diameter of rotor 183 being 1.0 mm., 1.5 mm., 2.0
`mm., 2.5 mm. and 3.0 mm., respectively. When the
`diameter of rotor 183 is 3 mm.(i.e. rotor inertia moment
`
`5
`
`i 5
`
`20
`
`25
`
`35
`
`40
`
`45
`
`30
`
`55
`
`60
`
`65
`
`8
`15), the maximum frequency of the a.c. magnetic field
`created by charging coils 106 and 106’ is 200 hertz.
`Therefore, at rotor inertia moment I5 the frequency of
`the a.c. magnetic field must be greater than 200 hertz to
`avoid adversely affecting hand movement of wrist-
`watch 117. Similarly, for inertia moments I2 and I1 the
`a.c. magnetic field frequency must be greater than 500
`hertz and 600 hertz, respectively, to prevent the hand
`movement of wristwatch 117 from being adversely
`affected. Generally, wristwatch 117 will have a rotor
`diameter of no greater than 3.0 mm.and noless than 1.0
`mm. The maximum rotor diameter of approximately 3.0
`mm. is based on the limitation of the measure. The mini-
`mum rotor diameter is based on the manufacturinglimi-
`tations(i.e. processing capacity) in producing rotor 183.
`Most small sized thin type analog electronic wrist-
`watcheshave rotor diameters of 1.5 mm.or less. Conse-
`quently, an a.c. magnetic field frequency of greater than
`500 hertz can be used without creating any adverse
`effect on the hand movementof wristwatch 117.
`FIG.7 illustrates the induced current measured in
`microamperes produced by coil 118 for charging bat-
`tery 121 plotted against
`the a.c. magnetic field fre-
`quency. Charging coils 106 and 106’ each have a wire
`diameter of approximately 0.3 mm., a winding number
`of 170 turns and inductance of 0.64 millihenries. Coil
`118 has a wire diameter of approximately 0.035 mm., a
`winding number of approximately 3830 turns and an
`inductance of approximately 0.5 henries. With charging
`coils 106 and 106’ and coil 118 having the aforemen-
`tioned values, the induced current peaks at a frequency
`of about 1,000 hertz. Since a frequency of 1,000 hertz is
`within region I of FIG. 6, by adjusting oscillator 101 so
`that output signal SO has a frequency of approximately
`1,000 hertz a maximum induced current in coil 118 is
`provided without adversely affecting the movement of
`rotor 183.
`FIG.8 illustrates wrist-watch 117 mounted to charg-
`ing device 100. A pair of fixing members such asfingers
`124 and 124’ are positioned on a top surface 129 of
`casing 123. During charging of watch 117, a wristband
`135 of watch 117is slid into and received by fingers 124
`and 124’ so as to properly position coil 118 of watch 117
`relative to charging coils 106 and 106’ of charging de-
`vice 100. LED 109is positioned within casing 123 so as
`to be seen when viewed from top surface 129. Switch
`107, which is pressed for starting timer 108, is also ac-
`cessible from top surface 129.
`As shown in FIG. 9, screws 125 and 125’ extend
`through openings 114 and 114’ of coil yoke 112 and are
`screwed into a pair of openings 139 of casing 123 for
`securely disposing coil yoke 112 and charging coils 106
`and 106’ at a predetermined location within casing 123.
`Consequently, charging coils 106 and 106’, coil yoke
`112 and coil 118 are positioned relative to each other as
`shownin FIG.5 to efficiently couple magnetic flux 122
`from coils 106.and 106’ to coil 118. Other suitable fixing
`members or materials such as adhesive can be used in
`lieu of screws 125 and 125’ for securing the assembly of
`coil yoke 112 and charging coils 106 and 106’ to casing
`123.
`As nowcan be readily appreciated, charging appara-
`tus 100 is far more efficient than conventional charging
`apparatuses for transferring energy from an external
`source to an electronic device. Charging apparatus 100
`does not adversely affect the operation of a watch’s
`hand movement or adversely affect any other analog
`movements of watch 117. Since electromagnetic induc-
`
`11
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`11
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`4,873,677
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`5
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`9
`tion is employed for charging, no’‘mechanical connector
`is required to transfer energy to battery 121 for charg-
`ing the latter. Charging apparatus 100 does not limit as
`severely the shape of watch 117 and,in particular, the
`external ornamental appearance of watch 117 as com-
`pared to watches employing conventional charging
`apparatus. Furthermore, charging coils 106 and 106’
`and coil yoke 112 are positioned to provide an efficient
`coupling of magnetic flux 122 to coil 118. Charging
`device 100 is also applicable for charging other types of 10
`electronic devices in addition to analog electronic
`wristwatch 117 such as card-type pocketradios, liquid
`crystal pocket televisions or the like.
`It will thus be seen that the objects set forth above,
`and those made apparent from the preceding descrip- 15
`tion are efficiently attained and, since certain changes
`may be madein the above methodand construction set
`forth without departing from the spirit and scope of the
`invention,it is intended that all matter contained in the
`above description and shown in the accompanying 20
`drawingsshall be interpreted asillustrative and not in a
`limiting sense.
`It is also to be understood that the following claims
`are intended to coverall the generic and specific fea-
`tures of the invention herein described and all state- 25
`ments of the scopeofthe invention, which as a matter of
`language, might be said to fall therebetween.
`Whatis claimed is:
`1. An apparatus for charging a power storage device
`provided within an electronic device which also in- 30
`cludes at least one secondary coil, said apparatus com-
`prising:
`a powersource f