Electromagnetic induction type charging device

An electromagnetic induction type charging device for charging a battery device has a charging paddle and a receptacle. The charging paddle has an infrared communication apparatus for communicating between the paddle and the receptacle. The housing of the charging paddle is made of a material that transmits infrared waves.

BACKGROUND OF THE INVENTION
 The present invention relates to electromagnetic induction type charging
 devices for charging batteries of electric vehicles through
 electromagnetic induction.
 Generally, there are two types of charging devices for electric vehicles,
 that is, a conductive type and an inductive type. Both types have a
 charging paddle connected with a power supply located at a fixed position.
 A typical electric vehicle has a receptacle for receiving power to charge
 its battery. The conductive type charging device charges the battery when
 the charging paddle contacts the receptacle. In this case, the charging
 paddle and the receptacle function as conductors. However, the inductive
 type charging device charges the battery through electromagnetic
 induction. In other words, the charging paddle need not be in contact with
 the receptacle when charging the vehicle's battery. Thus, the inductive
 type charging device is more reliable than the conductive type charging
 device. Furthermore, the inductive type charging device minimizes the size
 of the receptacle of the electric vehicle.
 As shown in FIG. 9, a typical inductive type charging device includes a
 cable 82, a power supply 81, and a charging paddle 83. The cable 82
 connects the charging paddle 83 to the power supply 81. The charging
 paddle 83 has a housing 83a accommodating a ferrite core 84 and a primary
 coil 85 wound around the core 84. For charging a battery of an electric
 vehicle, the charging paddle 83 is inserted in a slot (not shown) of a
 receptacle (not shown) of the vehicle. The receptacle has a secondary
 coil. When the charging paddle 83 is inserted in the receptacle slot, the
 power supply 81 supplies alternating current to the primary coil 85 of the
 charging paddle 83. The primary coil 85 thus induces electromotive force
 in the secondary coil of the receptacle for charging the battery of the
 vehicle.
 The inductive type charging device includes a controller for controlling
 the charging operation of the charging device. For example, the controller
 locks, or suspends, the charging operation until the charging paddle 83 is
 coupled with the receptacle. The controller also determines a target
 charging speed (target electric current) based on parameters such as the
 voltage of the battery and monitors the voltage of the battery while
 charging the battery. The controller executes these procedures in
 accordance with information sent by radio communication between the
 charging paddle 83 and the receptacle of the vehicle. Specifically, the
 charging paddle 83 includes an antenna 86 for performing radio
 communication with an antenna (not shown) of the vehicle's receptacle. A
 typical frequency band employed in the radio communication ranges from
 several hundreds MHz to several thousands MHz.
 However, the frequency band available for radio communication varies among
 different countries or regions. Thus, it is necessary to provide different
 types of charging paddles and corresponding receptacles that are
 applicable to different frequency bands, for example, a type for Japan, a
 type for U.S.A., and a type for Europe. As more types of charging paddles
 and corresponding receptacles are required, the manufacturing costs will
 increase.
 Furthermore, other radio devices such as cellular phones are often mounted
 in the vehicle. The radio waves emitted by these devices may cause noise
 in the radio communication performed by the charging device, and the radio
 waves emitted by the charging device cause noise in the other devices.
 To solve this problem, Japanese Unexamined Patent Publication No. 10-322919
 describes a charging device for electric vehicles that employs optical
 communication. The optical communication is not affected by radio noise of
 the devices mounted in the vehicle and transmits information in a stable
 manner. Specifically, this charging device employs an infrared type
 optical communication element.
 The charging device includes a resin housing for accommodating the charging
 paddle. The housing has a window for passing the infrared ray emitted by
 the communication element. That is, the housing includes a recess formed
 at a position corresponding to a light path of the optical communication
 element. A transparent, synthetic resin window is fitted in the recess
 such that the outer surface of the window is flush with the outer surface
 of the housing. In other words, it is necessary to manufacture the window
 separately from the protective housing. This structure increases the
 number of the housing parts and complicates assembly.
 Furthermore, since the window is adhered to the housing, the window becomes
 loose from the housing when the adhesive deteriorates. Thus, a space may
 be formed between the window and the housing, which unseals the housing.
 Furthermore, the window may eventually separate from the housing.
 Furthermore, the receptacle mounted in the vehicle needs to be miniaturized
 for saving space. If the receptacle is miniaturized, the charging paddle
 also must be miniaturized to match the receptacle.
 In addition, since the charging paddle is symmetric, the charging paddle
 may be inserted in the receptacle with the wrong side of the paddle facing
 the communication element of the receptacle. That is, the communicating
 element of the charging paddle will not be located at an optimal position
 for communicating with the communicating element of the receptacle.
 SUMMARY OF THE INVENTION
 Accordingly, it is a first objective of the present invention to provide an
 electromagnetic induction type charging device that performs infrared ray
 communication between a charging paddle and a receptacle of an electric
 vehicle to ensure high communication reliability, even with a paddle
 housing formed entirely of non-transparent resin.
 It is a second objective of the present invention to provide a charging
 device having a charging paddle that can be inserted in a receptacle
 regardless of which side of the charging paddle faces the communicating
 element of the receptacle.
 It is a third objective of the present invention to miniaturize a charging
 device employing infrared ray communication.
 To achieve the above objective, the present invention provides an
 electromagnetic induction type charging paddle for engaging a receptacle
 to charge a battery. The charging paddle has a first coil, a first
 infrared communication apparatus sends or transmits data between the first
 communication apparatus and a second communication apparatus. A housing of
 the charging paddle accommodates the first coil and the first
 communication apparatus. The housing is made of a material that transmits
 infrared waves.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 An electromagnetic induction type charging device for electric vehicles of
 a first embodiment according to the present invention will now be
 described with reference to FIGS. 1 to 6.
 As shown in FIG. 6, an electromagnetic induction type (inductive type)
 charging device 1 includes a charging paddle 2 and a receptacle 3. A power
 supply 4 is located at a fixed position and has a cable 5 extending from
 the power supply 4. The charging paddle 2 is secured to the distal end of
 the cable 5. A receptacle 3 is provided at a predetermined position (for
 example, in FIG. 6, at the front end of the hood) of an electric vehicle
 6. The charging paddle 2 includes an insert 2a and a grip 2b. The insert
 2a is inserted in a slot 3a formed in the receptacle 3. The charging
 paddle 2 and the power supply 4 constitute a feeder apparatus.
 When charging a battery 8 of the electric vehicle 6, the insert 2a of the
 charging paddle 2 is inserted in the slot 3a of the receptacle 3 as
 indicated by broken lines in FIG. 6. With the charging paddle 2 coupled
 with the receptacle 3, optical communication is performed between the
 charging paddle 2 and the receptacle 3. The power supply 4 has a
 controller 7, which is a control means. The controller 7 supplies an
 optimal alternating current to the charging paddle 2 through the cable 5
 in accordance with information obtained through the optical communication.
 The controller 7 locks, or suspends, charging until it is confirmed that
 the charging paddle 2 is coupled with the receptacle 3 through the optical
 communication. The controller 7 also detects the voltage of the battery 8
 and determines charging conditions such as a target electric current in
 accordance with the voltage. When the power supply 4 supplies alternating
 current to the charging paddle 2, the charging paddle 2
 electromagnetically induces a current in the receptacle 3. The current is
 then sent to the battery 8 of the electric vehicle 6 such that the battery
 8 is charged. While charging the battery 8, the controller 7 monitors the
 voltage of the battery 8.
 The configuration of the charging paddle 2 will hereafter be described. As
 shown in FIG. 2, the charging paddle 2 has a flat housing 10 including the
 insert 2a and the grip 2b. The housing 10 houses a disk-like ferrite core
 11 and a primary coil 12 wound around the core 11. A circuit board 13 is
 located substantially in the middle of the housing 10. In the first
 embodiment, the primary coil 12 employs litz wire. As shown in FIG. 13,
 the wire of the primary coil 12 and a wire 13a of the circuit board 13 are
 electrically connected with the power supply 4 via the cable 5.
 The circuit board 13 has electronic communication components. Specifically,
 as shown in FIG. 2, the circuit board 13 includes a substrate 14 having a
 pair of infrared communication elements 15, 16 (only one is shown) and
 corresponding communication integrated circuits (IC's) 17 (only one is
 shown). While the infrared communication element 15 is provided on one
 side of the substrate 14, the opposite infrared communication element 16
 is provided on the other side of the substrate 14. In the same manner, the
 communication IC's 17 are each located on opposite sides of the substrate
 14 at positions corresponding to the associated infrared communication
 elements 15, 16. The communication IC's 17 actuate the infrared
 communication elements 15, 16. In other words, the apparatus of the first
 embodiment performs infrared ray communication using the infrared
 communication elements 15, 16. The communication standard of this
 embodiment is the IrDA standard with an infrared wavelength of about 880
 nm. However, other infrared communication standards and other infrared
 wavelengths may be employed.
 As shown in FIG. 3, the infrared communication elements 15, 16 are opposite
 to each other with the substrate 14 arranged between them. Thus, when the
 charging paddle 2 is inserted in the receptacle 3, either the infrared
 communication element 15 or the infrared communication element 16 is
 located at an optimal position for communicating with a communicating
 portion of the receptacle 3. That is, the charging paddle 2 may be
 inserted in the receptacle 3 in either of the two possible orientations,
 and one of the communication elements will face the communicating portion
 of the receptacle 3. The infrared communication elements 15, 16 each
 include an infrared emitter 18 and an infrared receiver 19.
 The housing 10 is formed of infrared ray transmitting resin. Specifically,
 the housing 10 is formed of infrared ray-transmitting polycarbonate resin
 coated with a non-transparent infrared wave-transmitting paint. As
 described above, if a separate window of infrared ray transmitting resin
 is fitted in a portion of the housing corresponding to the infrared path,
 the number of housing parts increases, thus complicating the assembly of
 the housing. However, in this embodiment, since the entire housing 10 is
 formed of infrared wave transmitting resin, this problem is avoided.
 The communication IC's 17 constitute part of a communication circuit
 between the infrared communication elements 15, 16 and the controller 7.
 Each communication IC 17 functions as a driver for controlling the
 operation of the associated communication element 15, 16 in accordance
 with signals received mainly from the controller 7. The communication IC
 17 includes a filtering circuit for filtering noise from the signals. The
 communication IC 17 further includes an amplifying circuit for amplifying
 the signals. The filtering circuit and the amplifying circuit of the
 communication IC's 17 are located in the vicinity of the associated
 infrared communication elements 15, 16.
 The communication circuit between the infrared communication elements 15,
 16 and the controller 7 includes a first unit 20 and a second unit 21. As
 shown in FIG. 4, the first unit 20 is accommodated in the charging paddle
 2 and is located in the vicinity of the infrared communication elements
 15, 16. The second unit 21 is incorporated in the controller 7.
 The second unit 21 has a pulse control circuit and a filtering circuit. The
 pulse control circuit modulates the operating frequency such that the
 communication standard of the controller 7 matches the IrDA standard. The
 filtering circuit filters noise from signals sent to the controller 7 by
 the infrared receivers 19 of the infrared communication elements 15, 16.
 In the first embodiment, the communication circuit has two parts: the first
 unit 20 and the second unit 21. Only the first unit 20 is accommodated in
 the housing 10 of the charging paddle 2. This structure decreases the
 number of parts in the housing 10 of the charging paddle 2. Specifically,
 the first unit 20 does not include the infrared communication elements 15,
 16 but includes the remainder of the circuit board 13. The first unit 20
 and the second unit 21 constitute a first circuit and a second circuit,
 respectively.
 The charging paddle 2 is inserted in the receptacle 3, as shown in FIG. 1.
 The housing 10 of the charging paddle 2 includes a pair of housing
 portions 10a, 10b. The housing portions 10a, 10b are coupled with each
 other through vibrating deposition to form the housing 10. The ferrite
 core 11 is incorporated in the charging paddle 2 such that the sides of
 the charging paddle 2 are flush with the ends of the ferrite core 11,
 respectively.
 The configuration of the receptacle 3 will hereafter be described with
 reference to FIG. 1.
 The receptacle 3 has a housing 30 secured to the electric vehicle 6. A
 ferrite core 31 is accommodated in the housing 30. When the insert 2a of
 the charging paddle 2 is inserted in the slot 3a of the receptacle 3, the
 ferrite core 11 of the charging paddle 2 opposes the ferrite core 31 of
 the receptacle 3. The ferrite core 31 is shaped substantially like a
 square frame to encompass the insert 2a. The ferrite core 31 includes a
 pair of beam-like yokes 31a, 31b. A pair of disk-like pole projections 32,
 33 are each projected from the associated yokes 31a, 31b toward the
 ferrite core 11. A secondary coil 34 is wound around the pole projection
 33. When the insert 2a of the charging paddle 2 is inserted in the slot 3a
 of the receptacle 3, the ferrite core 11 is located between the pole
 projections 32, 33. In this state, the ferrite core 11, the primary coil
 12, and the secondary coil 34 define a closed magnetic circuit.
 The housing 30 has a cavity 30a located near the slot 3a for accommodating
 a circuit board 35, which is a communication device. The cavity 30a has an
 opening covered by a lid 30b. The circuit board 35 has a substrate 36
 including a communication IC 37 and an infrared communication element 38.
 When the insert 2a of the charging paddle 2 is received in the slot 3a of
 the receptacle 3, the infrared communication element 38 of the receptacle
 3 opposes one of the infrared communication elements 15, 16 of the
 charging paddle 2, and the housing portion 10b is arranged between the
 communication elements. In this manner, the infrared communication element
 38 of the receptacle 3 communicates with the corresponding infrared
 communication elements 15, 16 of the charging paddle 2.
 The electrical configuration of the charging device 1 will be hereafter
 discussed with reference to the circuit diagram of FIG. 5.
 The controller 7 controls an inverter 41 by means of a gate controller 40
 in accordance with signals from the infrared communication elements 15,
 16. The inverter 41 is a normal, single phase inverter having an H-shaped
 bridge structure including four IGBT's. Alternating current from an
 external power source (not shown) is rectified such that direct current
 voltage is obtained. The obtained direct current voltage is then converted
 by the inverter 41 into alternating current voltage having a frequency of
 about 10 kHz to 100 kHz. The resulting alternating current is sent to the
 primary coil 12. The primary coil 12 then electromagnetically induces an
 alternating current voltage in the secondary coil 34. The alternating
 current voltage is then rectified by a rectifying circuit 42.
 Subsequently, the alternating current voltage is smoothed by a smoothing
 circuit 43 and supplied to the battery 8.
 A first voltage dividing circuit 44 has a pair of resistance elements 45,
 46 connected in series. The resistance elements 45, 46 each have a
 relatively high resistance. A second voltage dividing circuit 47 has a
 pair of resistance elements 48, 49 connected in series. The resistance
 elements 48, 49 each have a relatively high resistance. The first voltage
 dividing circuit 44 divides the voltage applied from the rectifying
 circuit 42 and sends an analog signal indicating the obtained value to a
 controller 50. The second voltage dividing circuit 47 divides the voltage
 of the battery 8 and sends an analog signal indicating the obtained value
 to the controller 50. The controller 50 determines that the battery 8 is
 being charged when the signal from the first voltage dividing circuit 44
 indicates an increased value. The controller 50 converts the analog signal
 sent from the second voltage dividing circuit 47 to digital form. The
 controller 50 determines the state of the battery 8 in accordance with the
 obtained digital signal.
 When the charging paddle 2 is separated from a hook (not shown) of the
 power supply 4, the infrared emitter 18 of the corresponding infrared
 communication element 15 (16) emits infrared waves. When the insert 2a of
 the charging paddle 2 is inserted in the receptacle 3, a locking signal
 for suspending the charging operation is sent through the infrared
 communication element 15 (16) to the controller 50. The controller 50
 receives the locking signal through the infrared communication element 38.
 Subsequently, the controller 50 instructs the infrared emitter 18 of the
 infrared communication element 38 through the communication IC 37 to send
 a permission signal for permitting the charging operation and a voltage
 signal indicating the voltage of the battery 8 to the controller 7. The
 controller 7 receives the permission signal and the voltage signal through
 the corresponding infrared communication element 15 (16). If the voltage
 of the battery 8 indicated by the voltage signal is lower than a
 predetermined value, the controller 7 determines that the battery 8 needs
 be charged. The controller 7 then controls the gate controller 40 such
 that the charging operation is initiated with power corresponding to the
 current voltage of the battery 8.
 While the charging operation is being performed, the controller 50
 periodically sends the digital signal indicating the voltage of the
 battery 8 to the controller 7 through communication between the infrared
 communication element 38 and the corresponding infrared communication
 element 15 (16). The digital signal sent from the controller 50 enables
 the controller 7 to monitor the voltage of the battery 8. Accordingly, the
 controller 7 supplies an optimal electric current to the battery 8
 depending on the voltage of the battery 8. When the digital signal
 indicates that the voltage of the battery 8 has reached a predetermined
 value, the controller 7 acknowledges that the battery 8 is fully charged.
 The controller 7 then instructs the gate controller 40 to stop the
 charging operation.
 The first embodiment has the following advantages.
 In the first embodiment, infrared communication is performed between the
 charging paddle 2 and the receptacle 3. This structure enables the
 charging device 1 to use one international communication standard. That
 is, unlike a charging device using radio communication, the communication
 standard of the charging device 1 need not be altered for matching
 different frequency bands of different countries or regions. In other
 words, it is possible to manufacture charging devices in accordance with a
 single international communication standard. Furthermore, the charging
 device 1 does not cause noise in other radio communication devices mounted
 in the electric vehicle 6 such as cellular phones.
 The housing 10 of the charging paddle 2 is formed of infrared ray
 transmitting resin. Thus, when an infrared signal passes through the
 housing 10, the signal intensity is not damped. This structure increases
 the communication reliability of the charging device 1. Furthermore, since
 the entire housing 10 is formed of infrared ray transmitting resin, it is
 not necessary to provide a separate window of infrared ray transmitting
 resin. This structure decreases the number of housing parts, thus
 simplifying the assembly of the housing 10. Accordingly, the cost for
 manufacturing the charging paddle 2 is reduced. In addition, since the
 housing 10 of the first embodiment does not include a separate window
 piece, the problems of the prior art not occur.
 Non-transparent resin is used for this invention. The resin transmits the
 infrared waves but not visible light. Therefore, the interior of the
 charging paddle is not visible form outside the housing while the battery
 is being charged, which is preferred.
 In the first embodiment, the communication circuit between the infrared
 communication elements 15, 16 and the controller 7 is divided into two
 sections: the first unit 20 and the second unit 21. Since the first unit
 20 must be located in the vicinity of the infrared communication elements
 15, 16, the first unit 20 is accommodated in the housing 10 of the
 charging paddle 2. However, the second unit 21 is incorporated in the
 controller 7, which is provided in the power supply 4. This arrangement
 minimizes the number of parts in the housing 10 of the charging paddle 2,
 thus permitting the size of the charging paddle 2 to be reduced.
 In the first embodiment, a pair of infrared communication elements 15, 16
 are each provided on opposite sides of the charging paddle 2. Thus, when
 the insert 2a of the charging paddle 2 is located in the slot 3a of the
 receptacle 3, communication is ensured between the charging paddle 2 and
 the receptacle 3, without considering which side of the charging paddle 2
 faces the communication element 38 of the receptacle 3. In other words,
 the charging paddle 2 may be inserted in the receptacle 3 regardless which
 side of the charging paddle 2 faces the communication element 38.
 A second embodiment of the present invention will hereafter be described
 with reference to FIGS. 7 and 8.
 In the second embodiment, a single infrared communication element 15 is
 provided in the charging paddle 2. In the following, the difference
 between the first embodiment illustrated in FIGS. 1 to 6 and the second
 embodiment will mainly be discussed. Same or like reference numerals are
 given to same or like components.
 FIG. 7 is a cross-sectional view schematically showing the charging paddle
 2 of the second embodiment coupled with the receptacle 3. Like the first
 embodiment, the housing 10 of the second embodiment is formed by coupling
 the housing portions 10a, 10b through vibrating deposition. The housing 10
 is formed entirely of infrared wave transmitting resin.
 As shown in FIGS. 7 and 8, the circuit board 13 of the charging paddle 2 is
 housed in a water-proof casing 60 formed of transparent synthetic resin.
 An infrared communication element 15 is provided on the circuit board 13.
 The infrared communication element 15 includes the infrared emitter 18 and
 the infrared receiver 19, like the first embodiment. The infrared
 communication element 15 is located in the charging paddle 2 such that the
 infrared emitter 18 of the element 15 emits waves along a path parallel to
 the sides of the charging paddle 2, and the infrared receiver 19 of the
 element 15 receives light along a similar path.
 A prism 61, which is a spectral diffraction means, is secured to the
 water-proof casing 60 and is aligned with the emitter 18 and the receiver
 19 of the infrared communication element 15. As shown in FIG. 8, the prism
 61 includes a refraction surface 61a for dividing an infrared beam emitted
 by the infrared emitter 18 into two beams. When the insert 2a of the
 charging paddle 2 is received in the slot 3a of the receptacle 3, the
 beams extend in opposite directions along a path perpendicular to the
 substrate 36 of the circuit board 35 on which the infrared communication
 element 38 is located.
 The housing 30 of the receptacle 3 is formed of metal. A box 62 formed of
 infrared ray transmitting resin is accommodated in the housing 30 and
 houses the circuit board 35, which is a communication device. When the
 insert 2a of the charging paddle 2 is received in the slot 3a of the
 receptacle 3, the circuit board 35 substantially faces the circuit board
 13 of the charging paddle 2. The circuit board 35 includes the infrared
 communication element 38, which includes an infrared emitter 18 and an
 infrared receiver 19. The infrared communication element 38 is located on
 the circuit board 35 such that infrared emitter 18 of the element 38
 infrared waves along a path parallel to the sides of the charging paddle
 2, and the receiver 19 of the element 38 receives infrared waves along a
 similar path. prism 63, which is a spectral diffraction means, is located
 on the circuit board 35 and is aligned with the infrared emitter 18 and
 the infrared receiver 19 of the infrared communication element 38.
 The prism 63 includes a refraction surface 63a for refracting infrared
 waves emitted by the emitter 18 of the infrared communication element 38.
 The infrared beam refracted by the refraction surface 63a extends to the
 prism 61 of the charging paddle 2. The light is then refracted by the
 refraction surface 61a and is directed to the infrared receiver 19 of the
 infrared communication element 15. On the other hand, light emitted by the
 infrared emitter 18 of the infrared communication element 15 is refracted
 by the refraction surface 61a of the prism 61 and proceeds to the prism 63
 of the receptacle 3. The light is then refracted by the refraction surface
 63a of the prism 63 and is directed to the infrared receiver 19 of the
 infrared communication element 38.
 The housing 30 includes the lid 30c closing the opening of the box 62. The
 ferrite core 31 of the receptacle 3 includes a flat I-shaped core 64 and
 an E-shaped core 65 having a cylindrical pole projection 65a. When the
 insert 2a of the charging paddle 2 is received in the slot 3a of the
 receptacle 3, the ferrite core 11 is located between the cores 64, 65. In
 this state, a magnetic circuit is formed by the ferrite core 11, the
 I-shaped core 64, the E-shaped core 65, the coil 12 of the charging paddle
 2, and a coil board 66. The coil board 66 includes a coil wire 66a. A
 cooling fan 67 is secured to an end of the housing 30. When the fan 67 is
 activated, air flows along the charging paddle 2 in the housing 30, thus
 cooling the interior of the housing 30 heated by the coil 12 and the coil
 board 66.
 The second embodiment has the following advantages.
 In the second embodiment, the charging paddle 2 includes only one infrared
 communication element 15. However, when the insert 2a of the charging
 paddle 2 is located in the slot 3a of the receptacle 3, the infrared
 communication element 15 reliably communicates with the infrared
 communication element 38 of the receptacle 3 regardless of which side of
 the charging paddle 2 faces the infrared communication element 38.
 Furthermore, the beam from the infrared communication element 15 extends
 longitudinally parallel to the sides of the charging paddle 2, thus
 minimizing the dimension between the sides of the charging paddle 2.
 In the second embodiment, the prism 63 refracts the beam emitted by the
 infrared emitter 18 of the infrared communication element 38. The light
 thus proceeds toward the infrared receiver 19 of the infrared
 communication element 15 of the charging paddle 2. The prism 38 also
 refracts the beam emitted by the emitter 18 of the infrared communication
 element 15 of the charging paddle 2. The beam thus proceeds toward the
 receiver 19 of the infrared communication element 38 of the receptacle 3.
 This structure increases the acceptable range of positions for locating
 the infrared communication element 38 in the receptacle 3. Furthermore,
 the infrared communication element 38 extends longitudinally parallel to
 the sides of the charging paddle 2, thus minimizing the dimension between
 the corresponding sides of the receptacle 3.
 As described above, the structure of the second embodiment minimizes the
 size of the charging paddle 2 and the receptacle 3. The electromagnetic
 induction type charging device 1 is relatively small.
 The present invention may be modified as follows.
 The charging paddle 2 may include an antenna in addition to the infrared
 communication element 15. The charging paddle 2 may thus be used both for
 electric vehicles having prior-art radio communication type receptacles
 and those having infrared ray communication type receptacles.
 While the charging paddle 2 includes a single infrared communication
 element, a pair of infrared communication elements may be provided in the
 receptacle 3 at positions corresponding to opposite sides of the charging
 paddle 2. In this structure, when the charging paddle 2 is inserted in the
 receptacle 3, the infrared communication element of the charging paddle 2
 faces one of the infrared communication elements of the receptacle 3. The
 infrared communication between the charging paddle 2 and the receptacle 3
 is thus ensured.
 The communication circuit between the infrared communication elements 15,
 16 and the controller 7 is divided into the first unit 20 and the second
 unit 21. Only the first unit 20 is in the housing 10 of the charging
 paddle 2. However, the entire communication circuit may be located in the
 housing 10. Furthermore, if the communication circuit is divided into
 sections, the circuits types are not restricted to the embodiments
 illustrated in FIGS. 1 to 8.
 The infrared wave transmitting resin forming the housing 10 is not
 restricted to the non-transparent resin coated with infrared wave
 transmitting paint. Any resin may be used for forming the housing 10 as
 long as the resin transmits infrared waves.
 Each infrared communication element may include only a light emitter or a
 light receiver. In other words, the infrared ray communication may be
 performed in a one-way manner.
 Although the charging paddle 2 is inserted in the receptacle 3, the
 charging paddle 2 may be coupled with the receptacle 3 in a different
 manner. For example, the charging paddle 2 may be magnetically coupled
 with the receptacle 3. Alternatively, the charging paddle 2 may be engaged
 with the receptacle 3.
 Each infrared communication element may have a two-part structure having a
 light emitter and a light receiver.
 Information transmitted through infrared communication is not restricted to
 data concerning the charging of the battery 8. For example, data
 concerning the vehicle's engine may be transmitted through infrared ray
 communication while the battery 8 is being charged is an engine-driven
 vehicle.
 The present invention may be applied to vehicles driven by batteries other
 than electric passenger cars. For example, the present invention may be
 applied to industrial vehicles such as battery type forklifts and battery
 type transport trucks. Furthermore, the present invention may be applied
 to hybrid vehicles powered by both fuel (for example, gasoline) and
 batteries.
 In addition, the charging paddle 2 and the receptacle 3 according to the
 present invention may be applied to charging devices of batteries used for
 purposes other than electric vehicles.
 It should be apparent to those skilled in the art that the present
 invention may be embodied in many other specific forms without departing
 from the sprit or scope of the invention. Therefore, the present examples
 and embodiments are to be considered as illustrative and not restrictive
 and the invention is not to be limited to the details given herein, but
 may be modified within the scope and equivalence of the appended claims.