BATTERY CHARGING SYSTEM AND BATTERY CHARGING APPARATUS THEREOF
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a battery charging system and a
battery charging apparatus thereof that are adapted for use in combination
with mobile terminals. More specifically, the present invention relates to a battery charging system and a battery charging apparatus thereof that make
use of an induced voltage in charging a battery without terminal contact between a battery pack and the charging apparatus.
(b) Description of the Related Art
With the growth of communication and data processing technologies, the use of personal terminals that are handy to carry, such as mobile
telephones, camcorders, notebook computers, etc. is on an increasing trend and new models of terminals with enhanced performance are being
successively distributed.
Such mobile terminals generally have a small-sized internal or
external battery pack for ease of carrying and that operate with the power of
a rechargeable battery. The battery packs and their charging apparatuses
are manufactured so as to be suitable for the features and outward shape of
the individual terminals.
Conventional battery packs are designed such that it is necessary to
charge their battery with a direct contact between terminals of the built-in
battery and the charging apparatus, so that only a charging apparatus
specific to a particular battery pack terminal configuration can be used. It is
thus impossible to use a new model of battery pack with a different terminal
configuration in combination with the charging apparatus of an old one. So,
the user has to purchase an additional charging apparatus that matches a
battery pack with a new style of terminals. Furthermore, battery packs and
charging apparatuses that are unusable are generally abandoned or disposed of with a great economic loss to the nation as well as to the individual users.
SUMMARY OF THE INVENTION
It is an object of the present invention to overcome the above- mentioned problem and to provide a battery charging system and a charging apparatus thereof that are adapted for use in combination with various
mobile terminals and that make use of an induced voltage in charging a
battery without terminal contact between a battery pack and the charging apparatus.
To achieve the object of the present invention, there is provided a
battery charging system that includes a battery pack and a battery
charging apparatus and that charges the battery using communication
between the battery pack and the battery charging apparatus. The battery
pack includes: a power receiver for converting an externally induced
voltage to a DC voltage, the power receiver comprising an induction coil for
inducing the external voltage through a magnetic field, and a smoothing
circuit for converting the induced voltage to a DC voltage; a battery being
charged with the DC voltage supplied from the power receiver; a controller
including a microcontroller programmed with an algorithm for monitoring
the voltage and a current supplied to the battery, generating a control
signal based on a charging status of the battery and supplying a constant
voltage and a constant current to the battery for proper charging; and a
signal generator for generating a signal based on input of the control signal.
The battery charging apparatus includes: a filter for eliminating noise
included in external AC power and interrupting flow of a transient current; a
rectifier for converting the AC power supplied via the filter to DC power; a
power voltage generator for generating a power voltage using the AC
power supplied via the rectifier; a switching power section for generating a
switching power using the DC power supplied from the rectifier; a power
transmitter for generating an induced voltage using the switching power
supplied from the switching power section; a signal receiver for receiving
an external signal; and a power controller including a microcontroller
programmed with an algorithm for generating a control signal to the
switching power section based on a signal supplied from the signal
receiver and effecting proper charging.
In the battery charging system according to the present invention,
the signal generator and the signal receiver have a light-emitting optical
sensor and a light-receiving optical sensor, a light-emitting ultrasonic sensor
and a light-receiving ultrasonic sensor, or an RF-transmitting circuit and an
RF-receiving circuit.
In the battery charging system according to the present invention,
the switching power section includes a switching mode power supply.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating a battery pack in accordance
with the present invention;
FIG. 2 is a block diagram illustrating a charging apparatus in accordance with the present invention;
FIG. 3 is a side view showing the battery pack of the present
invention attached to a mobile phone; FIG. 4 is a perspective view illustrating the charging apparatus of the
present invention;
FIG. 5 is a perspective view showing the battery pack associated with the charging apparatus in accordance with the present invention;
FIG. 6 is a flow chart illustrating the power controller shown in FIG. 2; FIG. 7 is a flow chart illustrating the controller shown in FIG. 1 ; and
FIGS. 8(a) and 8(b) are diagrams illustrating a secondary coil and its
configuration in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, the present invention will be described in detail with
reference to the accompanying drawings.
FIG. 1 is a block diagram illustrating a battery pack in accordance
with the present invention.
An induced voltage from a power receiver 1 is supplied to a battery 2
to be charged, which comprises, for example, lithium-ion batteries. A
controller 3 monitors the voltage and the current supplied to the battery 2.
The controller 3 outputs a control signal to a signal generator 4 based on the
charging status of the battery 2. The signal generator 4, which comprises, for
example, light-emitting elements of an optical sensor, receives the control
signal and generates an optical signal having a predetermined frequency
based on the control signal.
The power receiver 1 comprises an induction coil for forming a
closed circuit from the magnetic field to induce a voltage, and a smoothing circuit for converting the induced voltage to a DC voltage.
The controller 3 monitors the voltage and the current supplied to the battery 2 to generate a control signal for charging the battery with a constant voltage and a constant current. For this purpose, the controller 3 may
comprise, for example, a microcontroller. With a built-in algorithm programmed to supply a constant voltage or a constant current to the battery
so as to properly charge the battery, the microcontroller generates a control
signal according to the execution of the program so that the signal generator
4 generates an optical signal.
Supply of a constant voltage or a constant current is necessary in
charging a battery. When the voltage. of the battery is less than 4.2 V, for
example, a constant current flows. At 4.2 V, a constant voltage is supplied
instead, while the charging current is gradually reduced. The charging
voltage should be 4.2 ± 0.05 V, with the charging current being about 0.35 to
1.0 CA.
The voltage at the open circuit of the battery is measured prior to
charge of the battery, and high-speed charging is effected when the battery
is dischargeable due to a protecting circuit. If discharge is not allowed, the
controller flows a small amount of current to make the battery dischargeable
and the voltage of the battery measurable. If the voltage exceeds 1.5 V, the
controller flows a small amount of current for a predetermined time (for
example, 30 min.) to start charging, and it again measures the voltage at the
open circuit of the battery. Charging is effected while the voltage of the battery is measurable. When the voltage is non-measurable or less than 1.5
V, or when no current flows, the system determines that the battery is abnormal and interrupts charging. The charging of the battery is determined based on the amount of current flowing. For example, a current of 0.1 CA
flows when the battery is 93 to 94 % charged.
FIG. 2 is a block diagram illustrating a charging apparatus in
accordance with the present invention, in which the charging apparatus is a device for charging a battery built in the battery pack shown in FIG. 1.
When AC power of 90 to 230 V or 50/60 Hz is externally supplied, a
filter 11 eliminates noise and interrupts a transient current. The AC power
supplied through the filter 11 is converted to DC voltage at a rectifier 12 and
is applied to a switching power section 13, which uses the DC voltage to
generate a switching voltage necessary for charging. The switching voltage
generated is supplied to a power transmitter 14, which then generates an
induced voltage.
Receiving the DC power from the rectifier 12, a power voltage
generator 15 generates a power voltage Vcc for driving the switching power
section 13 and a power controller 16.
A signal receiver 17 receives the optical signal from the signal
generator 4 of the battery pack and supplies the received signal to the power
controller 16. The power controller 16 outputs a signal for the control of the
switching power section 13 in order to effect proper charging of the battery
based on the signal received from the signal receiver 17.
Here, the filter 11 comprises a noise filter for eliminating noise
included in the AC power and a fuse for interrupting the flow of the transient
current, and the rectifier 12 comprises, for example, a bridge diode and an electrolytic condenser.
The switching power section 13, which is a device for generating a switching power necessary for charging, comprises a fly-back type switching
mode power supply (SMPS) and uses a current amplifier to make the switching power applicable to the load fluctuation rate on the receiver side.
Hence, the switching power section 13 receives a pulse width modulation
(PWM) type control signal from the power controller 16 and supplies a
switching power (e.g., over 100 KHz) to the power transmitter 14.
The power transmitter 14 generates an induced voltage from the
magnetic field generated by the switching power of the switching power
section 13, and for this purpose, uses an induction coil. So, the switching
power supplied to the induction coil (primary winding) of the power
transmitter 14 induces a voltage to the induction coil (secondary winding) of
the power receiver 1 of the battery pack.
The signal receiver 17, which comprises, for example, light-receiving
elements of an optical sensor, receives an optical signal generated from the signal generator 4.
The power controller 16 comprises a microcontroller with a built-in
algorithm programmed to effect proper charging based on the signal received through the signal receiver 17, i.e., a control signal generated from
the controller 3 of the battery pack, and it outputs a signal for the control of
the switching power section 13 according to the programmed algorithm. The power controller periodically detects the current consumed in
charging the battery with a current of 350 to 1000 mA so as to not supply an excess of power. The power controller also stands ready at the minimum current, and when the power transmit position reaches a position available to
transmit the power at over 80%, determines the existence of a battery to make the battery chargeable with a constant current.
That is, the microcontroller of the power controller periodically
monitors the charging status of the battery so as to minimize power consumption after the battery is fully charged.
The battery pack is attached to the charging apparatus by means of
a magnet in order to secure stability and power transmission of the battery
during the charge, and it is readily detached from the charging apparatus
with a reduced magnetic force when the battery is fully charged.
FIG. 3 illustrates the battery pack 100 of the present invention
adapted for use in combination with a general mobile phone, in which the
power receiver 1 may, for example, be located at portion "A".
FIG. 4 is an illustration of the charging apparatus 200 of the present
invention, in which the power transmitter 14 is located at portion "B" in order
to secure the contact area with the power receiver 1 of the battery pack, and
an adjusting member 201 is provided to facilitate the installation of the
battery pack on the charging apparatus 200 according to the size of the
battery. Additionally, a display 202, which comprises, for example, light- emitting diodes, is provided on the charging apparatus 200 to display the
charging status of the battery.
FIG. 5 shows the battery pack associated with the charging apparatus in accordance with the present invention, in which terminals of the battery pack are not in contact with terminals of the charging apparatus
because the apparatus charges the battery with a voltage induced by an induction coil rather than by way of contact between terminals, thereby
allowing the battery to be chargeable irrespective of the type of mobile terminal concerned.
FIG. 6 is a flow chart illustrating the power controller shown in FIG. 2.
As the power supply initializes the system in step 101 , the power
controller checks in step 102 whether the battery pack is installed. If no
battery pack is installed, the power controller enters a power saving mode, in
step 108. Upon decision step 102 determining that the battery pack is
installed, the power controller gets ready to transmit the power, in step 103.
Thereafter, the power controller detects an optical signal from the battery
pack, in step 104, calculates the power to transmit, in step 105, and checks
in step 106 whether the transmit power is zero. If the transmit power
calculated is zero, the power controller interrupts the output of a power
control signal to stop power transmission, in step 109, and enters the power
saving mode, in step 108. If the transmit power is not zero, the power
controller outputs a power control signal to effect power transmission, in step
107, and returns to step 104 to detect the optical signal. The amount of
transmit power depends on the optical signal output from the battery pack. FIG. 7 is a flow chart illustrating the controller shown in FIG. 1.
As the installation of the charging apparatus initializes the system in step 201 , the controller checks the status of the battery pack in step 202, and determines in step 203 whether the battery is in a chargeable status. With
the battery in a non-chargeable status, the controller tests the chargeability of the battery in step 210, and checks in step 211 whether the battery is
defective. If the battery is defective, the controller stops charging upon
decision step 213 determining that the battery is in a charging-prohibited status. Otherwise, the controller checks the status of the battery pack in step
202, and measures the voltage of the battery in step 204. If the
measurement is, for example, less than 4.2 V, the controller charges the
battery with a constant current in step 206, sends an optical signal indicating
the current value and continues to charge the battery with a constant current
until the voltage of the battery reaches 4.2 V. If the voltage of the battery is
equal to or greater than 4.2 V, the controller charges the battery with a
constant voltage in step 207, measures the charging current in step 208, and
checks in step 209 whether the charging current is less than 0.1 CA. If the
charging current measured is equal to or greater than 0.1 CA, the controller
continues charging the battery with a constant voltage in step 207. Otherwise,
the charging process terminates. Here, the controller sends the same optical
signal as in the case where the battery is charged with a constant current.
Particularly, the present invention enables communication between
the charging apparatus and the battery pack. Such communication between
the charging apparatus and the battery pack may be implemented by way of
optical sensors, and it will be explained in the following. With a light-emitting optical sensor built in the battery pack and a
light-receiving optical sensor in the charging apparatus, a built-in microprocessor of the battery pack sends data to the charging apparatus via the light-emitting optical sensor. The charging apparatus sends an optical signal, received through the light-receiving sensor, to its built-in
microprocessor via filtering and amplifying circuits. In regard to the form of
the communication data, transmit data may be communicated in a digitalized
form (i.e., determined as "0" or "1" depending on emission of infrared rays).
Alternatively, the transmit data may be sent in a data form modified with a
predetermined frequency and fed into the charging apparatus via filtering
and demodulating circuits. Examples of the optical sensor include an IR
(Infrared) sensor, a visible-ray sensor, a laser sensor, etc.
The present invention also implements communication between the
charging apparatus and the battery pack by way of ultrasonic sensors, as will
be described in the following.
With a light-emitting ultrasonic sensor built in the battery pack and a
light-receiving ultrasonic sensor in the charging apparatus, a built-in
microprocessor of the battery pack sends data to the charging apparatus via
the light-emitting ultrasonic sensor. The charging apparatus sends an IR
signal, received through the light-receiving ultrasonic sensor, to its built-in
microprocessor via filtering and amplifying circuits. In regard to the form of
the communication data, the transmit data may be communicated in the
digitalized form determined as "0" or "1" depending on emission of
ultrasonic waves. RF (Radio Frequency) communication between the battery pack and the charging apparatus is also available in the present invention.
With an RF-transmitting circuit built in the battery pack and an RF- receiving circuit in the charging apparatus, a built-in microprocessor of the battery pack sends data to the RF circuit, which modifies and amplifies the
data in the RF form and sends an RF signal to the charging apparatus. The
charging apparatus sends the RF signal, received through the RF-receiving circuit, to its built-in microprocessor via filtering, amplifying and demodulating
circuits. The modulation/demodulation method as used herein during data
communication may be a conventional one between digital and RF signals,
i.e., FSK, and so forth.
Hereinafter, a description will be given as to methods for recognizing
the battery pack in the present invention.
In a method for recognition of the battery pack using a light-emitting
optical sensor and a light-receiving optical sensor, the light-emitting optical
sensor and the light-receiving optical sensor for IR communication are
provided in the charging apparatus. The light-emitting optical sensor
periodically outputs an optical signal under the control of the microprocessor
in the charging apparatus. Then, the light-receiving optical sensor receives
the optical signal reflected from the battery pack to recognize the battery
pack that approaches the charging apparatus. Alternatively, the light-emitting
optical sensor is provided in the charging apparatus and the light-receiving optical sensor is in the battery pack. In this case, a very small amount of
power flows on the primary coil of the charging apparatus so that the battery pack senses power reception as it approaches the charging apparatus. Then,
the light-emitting optical sensor in the battery pack informs the built-in microprocessor of the charging apparatus about the approach of the battery
pack via optical communication.
In a method for recognition of the battery pack using a light-emitting
ultrasonic sensor and a light-receiving ultrasonic sensor, the light-emitting ultrasonic sensor and the light-receiving ultrasonic sensor for ultrasonic
communication are both provided in the charging apparatus. The light-
emitting ultrasonic sensor periodically outputs an ultrasonic signal under the
control of the microprocessor in the charging apparatus. Then, the light-
receiving ultrasonic sensor receives the ultrasonic signal reflected from the
battery pack to recognize the battery pack that approaches the charging
apparatus. Alternatively, the light-emitting ultrasonic sensor is provided in the
charging apparatus and the light-receiving ultrasonic sensor is in the battery
pack. In this case, a very small amount of power flows on the primary coil of
the charging apparatus, so that the battery pack senses power reception as
it comes closer to the charging apparatus. Then, the light-emitting ultrasonic
sensor in the battery pack informs the built-in microprocessor of the charging
apparatus about the approach of the battery pack via ultrasonic
communication.
In a method for recognition of the battery pack using an RF-
transmitting circuit and an RF-receiving circuit, the RF-transmitting circuit is
provided in the battery pack to flow a very small amount of power on the primary coil of the charging apparatus. So, the battery pack senses power
reception as it approaches the charging apparatus and the RF-transmitting circuit of the battery pack informs the built-in microprocessor of the charging
apparatus about the approach of the battery pack via ultrasonic communication.
In a method for recognition of the battery pack using a magnetic
switch, a magnet and a magnetic switch are provided either on the charging
apparatus and the battery pack or on the battery pack and the charging apparatus, respectively. As the battery pack approaches the charging
apparatus, the magnetic switch senses the approach of the battery pack and
informs a built-in microprocessor of the charging apparatus thereof using IR,
ultrasonic or RF communication by the aid of a light-emitting IR sensor, a
light-emitting ultrasonic sensor or an RF transmitting circuit in the battery
pack.
FIGS. 8(a) and 8(b) are diagrams illustrating a secondary coil and its
configuration according to the present invention, in which (a) shows a normal
enameled copper wire, and (b) shows a flexible PCB (Printed Circuit Board)
wire.
Conventional secondary coils used in power transmission with a
transformer or using induced electromotive force typically have a c- or E-
shaped core. But, the secondary coil of the present invention has an I-
shaped core in the form of a thin film. Unlike the conventional secondary
coils that are directly wound then laminated on a ι=- or ≡ -shaped core, the
secondary coil of the present invention, if composed of an enameled wire, is wound on a plane and then attached to the thin-film-type core. The
secondary coil of the present invention, if using an FPCB (Flexible Printed Circuit Board), is directly formed on the FPCB and then attached to the thin-
film-type core.
That is, with an l-shaped core in the form of a thin film, the secondary coil is formed from an enameled wire or directly on an FPCB on a
plane and then attached to the core. This minimizes the occupied area of the
core and the coil in the battery pack. In addition, the FPCB-based coil may form other electronic circuits in the battery pack on the FPCB to reduce the
entire volume of the battery pack.
As described above, the present invention charges a battery without
contact between the battery pack and the charging apparatus and makes a
battery changeable irrespective of the type and form of the mobile terminal
concerned. Thus, the user who has a new model of battery pack with a
different terminal style does not need to purchase a separate charging
apparatus, and hence no economic loss occurs due to disposal of the used
charging apparatus. When provided at public areas (e.g., terminals, stations,
airports, public offices, etc.) or on a vending machine, the charging
apparatus of the present invention may offer convenience to users of mobile
terminals.
The charging apparatus of the present invention is contrived to
control and transmit power necessary to the battery pack in real time, and it
is applicable to the battery charging system of any mobile terminal that has the correct circuit in the battery pack. It is thus possible to charge any
portable electrical appliance such as mobile communication equipment, PDA, portable audio equipment, etc. with only a single charging apparatus. Furthermore, the microprocessor in the battery pack memorizes the type,
features and charging method of batteries, so that the charging apparatus is applicable to any secondary batteries including lithium-ion, lithium-polymer
and the like.