Note: Descriptions are shown in the official language in which they were submitted.
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wTR~r.~,$ COMMUNICATION SYSTEM BETWEBN KEYPAD AND
TERMINAL
Field of the Invention
The present invention relates to a wireless
communications system interconnecting a hand-held
keypad and a base terminal. The invention relates
further to such a communications apparatus and
method, in which personal or sensitive information is
entered by the keypad.
Background of the Invention
Keypads are used daily at Point-Of-Sale (POS)
bank card payment devices to accept personal bank
account debits for purchases. At the POS, the cashier
asks the customer for a bank card, slides it through
a magnetic stripe reader, and enters the amount of
the purchase. The POS device dials up an electronic
funds transfer computer network to start the
transaction. The customer is given a keypad connected
to the POS device by a telephone cord. The keypad
includes a small Liquid Crystal Display (LCD), and
the first message displayed requests acceptance of
the amount of the purchase. The customer presses the
OK button in response to the request, and the next
message prompts the customer to select a bank account
type (i.e. checking, savings, etc.). After account
selection, the customer is prompted to enter a
Personal Identification Number (PIN). Each numeric
key entry appears on the LCD as an asterix, as is
common with all Automatic Teller Machines (ATM), in
order to prevent bystanders from seeing the PIN. Once
the customer presses the enter key after keying the
PIN, the device sends a request message to the
network to complete the transaction, including all
required information, such as account number, amount,
account type and PIN. The network transfers the
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requested amount electronically from the customer's
bank account to the store's account in accordance
with established procedures and protocols.
As is known in the art, the transmitted data is
encrypted to prevent fraud. The keypad is a
physically tamper-proof unit which codes the data
entered (namely the PIN) before transmitting it to
the POS device. In turn the data transmitted from the
POS device over telephone lines to the bank's
computer is also encrypted. International standards
for security and encryption have been established.
A difficulty with such POS devices is the
comfort in using the keypad which is connected to the
device by a relatively short and fragile cord. The
cord often gets in the way and compromises the
customer's ability to stand and hold the keypad in a
comfortable manner. Security of the transaction may
also be compromised by not holding the keypad in a
concealed fashion, allowing others to see the PIN
being keyed.
Summary of the Invention
Accordingly, it is an object of the invention to
provide a secure wireless communications system
including a base terminal and a keypad which allows
secure entry of data, even in public places, without
compromising the speed or efficiency of the data
entry and transfer to the base device.
According to the invention, there is provided a
wireless directional communication system for
communicating data between a hand held keypad and a
base terminal comprising wireless means connected to
the keypad and the base terminal for transmitting and
receiving data over a wireless medium and for
detecting an alignment signal when the keypad and the
base are substantially aligned with one another along
a communications axis, the alignment signal
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representing alignment of the wireless means for data
transmission and reception between the keypad and the
terminal, and indicator means for providing a message
indicative of a state of misalignment to a user of
the keypad in response to a failure to detect the
alignment signal.
Preferably, the alignment signal is a continuous
pulsed signal having a relatively short duty cycle
transmitted by the wireless means from the terminal
to the keypad, and data is transmitted between the
terminal and the keypad between pulses of the pulsed
signal at a fixed delay after the pulses, whereby the
alignment signal also synchronizes data transmission
between the terminal and the keypad. The indicator
means may comprise a display in the keypad, and the
message may comprise a text message on the display
for prompting the user to re-align the keypad with
the terminal. The keypad may also preferably comprise
buffer means for storing a sequence of keyed data
elements and for causing data representative of the
data elements to be sent over the wireless means in
response to a key press indicative of completion of
entry of the data elements, and the indicator means
may be connected to the buffer means, disabled from
displaying the message during entry at the keypad of
the data elements, and enabled to display the message
in response to failure to detect the alignment signal
once data entry is completed. In this way, the user
will not be prompted to maintain alignment between
the keypad and the terminal while holding the
terminal in a comfortable position during data entry,
until such data entry is completed.
The wireless means are preferably a pair of
infra-red transmitters and receivers, although radio
or ultrasound transceivers could also be implemented.
The indicator means can produce a visual and/or audio
message. The visual message can be a verbal text
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message or simply an indicator light. The message can
be provided either to the user of the keypad directly
and/or to a clerk near the user so that the clerk can
help the user direct the keypad to the terminal.
Depending on the application, the alignment signal
may be a separate signal from the data signal, either
transmitted using separate wireless means or the same
wireless means used for data, but in a separate time
frame. The alignment signal can also be integrated
with the data transmission protocol, i.e. the
alignment signal may be an acknowledgment signal in
response to transmission between the keypad and the
terminal. When the alignment signal is a continuous
pulsed signal, it can also be used to synchronize
data transmission.
The invention also provides a wireless
communication system for communicating data between a
hand held keypad and a base terminal comprising RF
wireless means connected to the keypad and the base
terminal for transmitting and receiving data
substantially omnidirectionally, the data being coded
according to a predetermined protocol, and closed
communication means connected to the keypad and the
base for transmitting and receiving information
specifying the protocol prior to transmitting and
receiving the data.
Brief Description of the Drawings
The invention will be better understood by way
of the following detailed description of a preferred
embodiment of the invention with reference to the
appended drawings, in which:
Fig. 1 is a perspective view of a wireless
communication system according to the preferred
embodiment showing a keypad, its charger-base
terminal, and a connector for connecting the
base terminal to a point-of-sale (POS) terminal;
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Fig. 2 is a block diagram of the circuit for the
keypad according to the preferred embodiment;
Fig. 3 is a block diagram of the circuit for the
terminal's signal converter according to the
preferred embodiment;
Fig. 4 is a signal envelope diagram illustrating
infra-red signal transmission between the
terminal and the keypad with a periodic
alignment code signal;
Fig. 5 is a diagram of a position detection
system for determining the position of the
keypad with respect to the transmission cone of
the base terminal's transmitter and receiver;
and
Fig. 6a and 6b show two further embodiments
incorporating omni-directional RF data
communication with an additional closed
communication path for initialization purposes.
DetAile~ Description of the Preferred Embodiment
In the preferred embodiment as shown in Fig. 1,
the wireless communication system comprises a mobile
hand-held wireless keypad terminal 10 and a mobile
signal converter base terminal 12 which plugs into a
point-of-sale (POS) terminal (not shown~. The base
12 comprises an infra-red transmitter 20 and receiver
22, as well as charging contacts 17 for charging
keypad 10 via its contact terminals 16 as the keypad
10 sits on top of the base 12. Base 12 is supplied
with DC power from an adapter 18, and plugs into the
POS terminal using connector lg. The preferred
embodiment is an add on to an existing terminal,
allowing the conventional wired hand-held keypad to
be replaced by terminals 10 and 12.
The invention is used by retail customers paying
for a purchase using their bank cards. The customers
give their bank cards to the cashier, and the cashier
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swipes the card through a magnetic stripe reader.
~ The cashier enters the amount of the purchase at the
POS terminal. The customer is then given keypad 10.
The customer points the keypad to base 12 and the
first message appears on screen 15, "Amount $XX.XX.
OK?", prompting the customer to press a designated
"OK" key on keyboard 14. The next message displayed
is "From which account?", prompting the customer to
press a bank account type key on keyboard 14, e.g.
"Checking" or "Savings". The next message is "Please
enter PIN, then OK.", prompting the customer to enter
his or her personal identification number (or code).
Each key press appears on the screen as an asterix to
confirm that a key was pressed, while concealing from
bystanders the PIN. When the customer finishes
entering the PIN, then the OK key is pressed. The
customer can hold the keypad 10 in a comfortable and
secure manner. If this comfortable manner causes the
keypad to lose contact with the base 12, then a
message requesting realignment is displayed.
However, if a customer chooses to enter his or her
PIN in such a fashion, the key presses will be
accepted. Once the OK key is pressed, signaling that
the entry is complete and ready to be sent, any
misalignment will cause the message to be immediately
displayed, and any such misalignment which is
prolonged, will cause a cancellation of the
transaction.
As shown in Fig. 2, the keypad 10 has an infra-
red transmitter 21 and receiver 23 for communicating
with the corresponding receiver 22 and transmitter
20, respectively, of the base 12. The data entry
keypad 14 and LCD screen display 15 are connected to
a microcontroller 30. The microcontroller is powered
by a battery 32, recharged by a charging circuit
including contacts 16. Controller 30 includes an
encryption and decryption program for encrypting
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entries from the keyboard 14 and for decrypting text
messages displayed on screen 15. Data to be
transmitted to the base 12 is sent from the
controller 30 to a modulator 34 which encodes the
digital data into modulated pulses for broadcasting
by transmitter 21. The optoelectronic receiver
circuit 23 demodulates the infra-red signal sent from
the base 12 and sends the received digital data to
controller 30. Circuit 23 also checks for an
alignment code continuously sent from the base 12 and
generates a misalignment signal to controller 30 if
the alignment code is not received, as will be
explained in better detail below.
Fig. 3 is a block diagram of the data
transmission and reception circuit used in the base
terminal 12 according to the preferred embodiment.
Encrypted messages from the POS terminal come in
connector bus 19 to a serial data port 46. The port
46 relays digital data to a modulator 44 which
produces a pulse modulated code signal representing
the data, the signal being output to the infra-red
optoelectronic transmitter 20. Infra-red light from
the keypad terminal 10 is received at a
phototransistor whose signal is amplified, filtered
and converted into digital data in the remainder of
the receiver circuit 22. The digital data is fed to
port 46 for transmission over bus 19 to the POS
terminal.
At the start of communication, or even at the
start of each transaction, the base 12 transmits a
code to keypad 10 which is interpreted by controller
to determine a special coding for the signals
transmitted from the keypad 10. For example, the
coding may comprise data transmission protocol
details, bit modulation coding formats, data packet
address codes (e.g. a serial number identifier) and
data encryption type or key.
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The infra-red signal is modulated to represent
the data according to conventional protocols,
however, in the preferred embodiment, the signal is
not continuous, but rather has an envelope as
illustrated in Fig. 4. The data part of the signal
is limited to 50ms intervals, separated by "silent"
50 ms intervals. In the silent intervals, a short
alignment code pulse is transmitted from the base
terminal (MSC) 12 to the keypad terminal (MHT) 10.
The keypad 10 also synchronizes its transmission to
the base 12 by the alignment code signal and
transmits during 50ms bursts as shown. The alignment
code signal is unique to the base terminal to avoid a
keypad 10 from communicating with a different base
terminal in a same store. The controller 30 (Fig. 2)
looks at the data received to ensure that the
alignment code signal is present between every data
group. If the alignment code signal is not present,
a misalignment flag is set. Since transmission to
the base 12 is to be synchronized with the reception
of the alignment code signal, transmission is stopped
when the misalignment flag is set.
If the keypad 12 is not in the process of
transmitting data, the controller 30 can respond in
different ways. In the preferred embodiment, a
message is immediately displayed on screen 15, e.g.
"Communication Lost. Please Keep Pointing Toward
Base". Other display or entry operations are
temporarily suspended. Once the alignment signal is
received again, the misalignment flag is cleared, and
normal operation of the controller 30 resumes. If
the misalignment is prolonged, even the entry
operations may be aborted. Data entered in the
keypad 10 would then be erased. The keypad would
then transmit a "cancel transaction" message to the
base 12 as soon as communication is re-established.
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In the case that the base 12 is integrated into
the POS terminal, messages could be generated for the
cashier, so that immediate attention and action is
possible.
Fig. 5 shows an embodiment of the invention
which includes position determining means. The
infra-red transmitter 20 of the base 12 has a cone of
transmission 25. Mounted in association with the
base 12 are three ultrasound transceivers 52, labeled
as C, V and H for center, vertical and horizontal,
respectively. Another ultrasound transceiver 50 is
mounted to the keypad 10. For clarity of
illustration, only the position of the infra-red
transmitter 20 and the transceivers 50 and 52 are
shown. The position of transceiver 50 is calculated
by triangulation after determining the distances
between it and each of the three transceivers 52.
Position determination using triangulation is
generally known in the art.
In the preferred embodiment, the intelligence of
the system is mostly in the microcontroller 30.
Therefore, the distance determination and
triangulation is done by the microcontroller. The
transceiver 50 can comprise three units receiving at
23kHz, 31kHz and 40kHz. The transceivers 52 can
comprise three corresponding units transmitting at
the three frequencies and located at C, V and H
respectively, a receiver also being provided at C. A
signal sent from transceiver 50 at the keypad is
received at C, and triggers the three transmitters to
sent a pulse. Controller 30 times the delay between
transmission of the trigger signal to reception of
the three pulses. The distances and position of
transceiver 50 is then calculated, as is known in the
art. If the keypad is near the boundary of cone 25,
a warning message can be displayed. The message can
indicate the direction in which the keypad needs to
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be moved to be within the cone 25, relative to the
established directions of up-down (V-C) and left-
right (H-C). The message could be textual or
graphic.
As can be appreciated the trigger signal could
be replaced by using the alignment code signal as a
timing reference. It would also be possible to
trigger transmitter C, V and H with different short
delays after the alignment code signal or the
ultrasound trigger signal, whereby the three
transmitters could operate at the same frequency.
Although the preferred embodiment uses infra-red
wireless transmission, ultrasound or RF could
alternatively be used. The indicator means according
to the preferred embodiment uses an alignment signal
and a screen display. It would also be possible to
detect misalignment as a result of a failure to
receive an acknowledgment signal after sending data.
The message indicating misalignment could be a simple
LED with a label identifying its meaning on the
keypad 10. The message could also be auditory,
namely a gentle beeping sound when misalignment
occurs.
For example, spread spectrum RF signaling at a
power level of less than lW can be used to provide
omni-directional data communication without needing
an FCC license. The frequency spectrum can be in the
902 to 928 MHz band. Due to the omni-directionality
of the data communication system, the invention
provides a closed communication link used for the
purposes of a private initialization between the base
and the keypad. A closed communication link is one
in which the information is not easily intercepted by
a receiver in the vicinity of the base and the mobile
keypad. As illustrated in Figs. 6a and 6b, a private
closed communication link can be a physical contact
terminal for a serial communication bus (Fig. 6a) or
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a short range infra-red or ultrasound communication
means operating within a relatively small confined
solid angle volume (Fig. 6b). When the cashier
swipes the bank card, initialization begins, as in
the preferred embodiment. The special coding is not
transmitted by the omni-directional RF transmitter
62, but rather is transmitted over the closed
communication link. This eliminates the possibility
that another receiver in the area listens in on the
communication between the keypad 10 and base 12 with
a view to analyzing the signals to determine the
encryption scheme, and ultimately the PIN codes and
possibly customer bank balance information being
transmitted.
Once the special coding is transmitted,
controller 30 places the prompt message on screen 15
for the customer to begin the transaction process
steps. At this point, the RF transmitters and
receivers 60 and 62, located in the keypad 10 and
base 12 respectively, communicate with each other
without needing to maintain alignment between the
keypad 10 and the base 12.
