Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SMART MULTI-TAP TEXT INPUT
FIELD OF THE INVENTION
[0001]The present invention relates to multi-tap text input using a reduced
keyboard. More particularly, the present invention relates to an improved
method and system for resolving ambiguities in multi-tap text input.
BACKGROUND OF THE INVENTION
[0002] The layout of the universal QWERTY keyboard is familiar to all typists
and
computer users. In this configuration, each alphanumeric symbol is assigned a
unique key. This configuration has dominated text input systems (including
typewriters and computers) for over a century. In recent years, however, the
development of new technologies like mobile telephones, personal digital
assistants (PDAs), and wireless two-way messaging devices has led to a
reconsideration of the configuration of keypads or keyboards. For example, in
the case of mobile telephones, three or more letters have been assigned or
associated with each numeric key. In the case of some two-way wireless
messaging devices, to conserve space, the devices have been designed with a
two-symbol-per-key keyboard. For example, such a device may feature a
reduced-key QWERTY keyboard, wherein the conventional QWERTY layout is
maintained, but two adjacent letters are associated with each key, e.g., one
key
is used for entering both the letters "E" and "R".
[0003] In a reduced-key input device, the keys have an associated sequence of
alphanumeric symbols or characters. For example, a key may be associated
with the letters JKL, as is the case with the "5" key on a telephone keypad.
Devices that use a reduced-key input interface for receiving text input
typically
operate in one of two modes. The first mode is a "multi-tap" mode. In multi-
tap
mode, the user selects one of the alphanumeric symbols or characters
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associated with a key by hitting the key a number of times in succession
corresponding to the position of the symbol in the sequence. For example, to
enter the letter "J", the user hits the "5" key once. To enter the letter "L",
the user
hits the "5" key three times.
[0004]Another mode of operation is a predictive mode in which the user only
hits
the key associated with the desired symbol once, without specifying which of
two
or more symbols the user actually wants. Once the user has pressed a number
of keys, the device uses predictive algorithms to attempt to guess which of
various possible combinations of symbols the user was most likely attempting
to
define. The user may be provided with a pick-list of candidates for selection.
In
this mode, the user only enters one keystroke for each desired symbol or
character.
[0005]When operating in the multi-tap mode, a difficulty arises in entering
two
successive symbols when those two symbols are associated with the same key.
For example, in a two-symbol-per-key context, a key may be associated with the
letters ER. When a user strikes this key three times in succession, it creates
an
ambiguity in determining the desired input. Three keystrokes may mean the user
wants to enter RE, or ER, or EEE.
[0006]To resolve this ambiguity, devices operating in multi-tap mode typically
employ a default rule, whereby the first two keystrokes will be interpreted as
a
multi-tap selection of the letter R. Because the user has reached the end of
the
sequence associated with the key, the next keystroke is interpreted as being
associated with the input of a new character, i.e., the letter E. Accordingly,
the
default understanding of three keystrokes is an output of RE.
[0007]To overcome this default rule and obtain an alternative output, like ER
or
EEE, the device may provide the user with a "next" key to indicate that the
user
is done selecting a character and that the cursor should be advanced to the
next
location. Subsequent keystrokes will be interpreted as the input of a new
character. Accordingly, to input ER, the user would strike the "ER" key once,
hit
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the "next" key, and then strike the "ER" key twice.
[0008]Another method of overriding the default rule is to wait for a timeout
to
occur. Typically, multi-tap input devices will provide a "timeout" feature,
wherein
the device presumes that a user is finished inputting a character if a
sufficiently
long period of time elapses following a keystroke. If a timeout occurs, then
the
device may advance the cursor to the next location in a text field on the
presumption that any subsequent keystrokes will relate to a new character.
Accordingly, to input ER, the user would strike the "ER" key once, wait until
the
cursor advances, and then strike the "ER" key twice.
[0009] It will be appreciated that using the "next" key to manually advance
the
cursor to the next location, or waiting for a timeout to automatically advance
the
cursor, results in a text input system that interferes with a user's keystroke
cadence or rhythm. Accordingly, a need exists for another method of resolving
multi-tap text input ambiguities.
SUMMARY OF THE INVENTION
[0010]The present invention provides a method of resolving multi-tap text
input
ambiguities based upon the timing of successive keystrokes of a selected key.
[0011] In one aspect, the present invention provides a method for resolving
ambiguities in multi-tap text input received through a reduced-key input
device, a
key of the input device having at least two associated text characters. The
method includes the steps of receiving a first keystroke signal associated
with
the key; receiving a second keystroke signal associated with the key;
comparing
a time between the first keystroke signal and the second keystroke signal with
a
timing value; and selecting between a default display output and an
alternative
display output based upon the comparison.
[0012] In another aspect, the present invention provides a multi-tap text
input
system for use with a device receiving multi-tap text input. The system
includes
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a keystroke timing component for storing keystroke timing information
including a
timing value; and a multi-tap text input module for receiving first and second
keystroke input signals associated with a key, the multi-tap input module
having
a timing module for determining a time between the first and second keystroke
input signals, a comparison component for comparing the timing value with the
time determined by the timing module, and a selection component, wherein the
selection component selects between a default display output and an
alternative
display output in response to the comparison component.
[0013] In yet a further aspect, the present invention provides a mobile
device.
The mobile device includes a reduced-key input device; a display; a memory
containing keystroke timing information including a timing value; and a multi-
tap
text input module for receiving first and second keystroke input signals
associated with a key, the multi-tap input module having a timing module for
determining a time between the first and second keystroke input signals, a
comparison component for comparing the timing value with the time determined
by the timing module, and a selection component, wherein the selection
component selects between a default display output and an alternative display
output in response to the comparison component.
[0014] Other aspects and features of the present invention will be apparent to
those of ordinary skill in the art from a review of the following detailed
description
when considered in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Reference will now be made, by way of example, to the accompanying
drawings which show an embodiment of the present invention, and in which:
[0016] Figure 1 shows a block diagram of a user device to which the present
invention is applied in an example embodiment;
[0017] Figure 2 shows an expanded diagram of a portion of the user device of
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Figure 1;
[0018] Figure 3 shows, in flowchart form, a method of providing for multi-tap
text
input;
[0019] Figure 4 shows, in flowchart form, a method for resolving ambiguities
in
multi-tap text input according to one embodiment of the present invention;
[0020] Figure 5 shows, in flowchart form, a method for resolving ambiguities
in
multi-tap text input according to another embodiment of the present invention;
[0021] Figure 6 shows, diagrammatically, a front view of an embodiment of a
user device having a reduced-key user interface; and
[0022] Figure 7 shows, diagrammatically, a front view of another embodiment of
a user device having a reduced-key user interface.
[0023] Similar reference numerals are used in different figures to denote
similar
components.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0024]The following description of one or more specific embodiments of the
invention does not limit the implementation of the invention to any particular
computer programming language or system architecture. The present invention
is not limited to any particular operating system, mobile device architecture,
or
computer programming language. Moreover, although some of the
embodiments described below include mobile devices, the present invention is
not limited to mobile devices, nor to wireless communications systems; rather,
it
may be embodied within any devices or terminals employing a multi-tap input
interface, including handheld devices, mobile telephones, wireless two-way
messaging devices, personal digital assistants (PDAs), personal computers,
audio-visual terminals, and other devices.
[0025] Referring now to the drawings, Figure 1 is a block diagram of a user
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device to which the present invention is applied in an example embodiment. In
the example embodiment, the user device is a two-way mobile communication
device 10 having data and possibly also voice communication capabilities. In
an
example embodiment, the device 10 has the capability to communicate with
other computer systems on the Internet. Depending on the functionality
provided
by the device 10, in various embodiments, the device may be a data
communication device, a multiple-mode communication device configured for
both data and voice communication, a mobile telephone, a PDA enabled for
wireless communication, or a computer system with a wireless modem, among
other things. In various embodiments, the present invention may also be
applied
to handheld computing devices, such as PDAs and digital cameras, that are not
enabled for communications.
[0026] In this embodiment, in which the device 10 is enabled for
communications, the device 10 includes a communication subsystem 11,
including a receiver 12, a transmitter 14, and associated components such as
one or more, preferably embedded or internal, antenna elements 16 and 18, and
a processing module such as a digital signal processor (DSP) 20. In some
embodiments, the communication subsystem 11 includes local oscillator(s) (LO)
13, and in some embodiments, the communication subsystem 11 and a
microprocessor 38 share an oscillator. As will be apparent to those skilled in
the
field of communications, the particular design of the communication subsystem
11 will be dependent upon the communication network in which the device 10 is
intended to operate.
[0027] Signals received by the antenna 16 through a wireless communication
network 50 are input to the receiver 12, which may perform such common
receiver functions as signal amplification, frequency down conversion,
filtering,
channel selection, and the like, and in some embodiments, analog to digital
conversion. In a similar manner, signals to be transmitted are processed,
including modulation and encoding, for example, by the DSP 20 and input to the
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transmitter 14 for digital to analog conversion, frequency up conversion,
filtering,
amplification, and transmission over the communications network 50 via the
antenna 18.
[0028] The device 10 includes the microprocessor 38 that controls the overall
operation of the device 10. The microprocessor 38 interacts with communication
subsystem 11 and also interacts with further device subsystems such as the
graphics subsystem 44, flash memory 24, random access memory (RAM) 26,
auxiliary input/output (I/O) subsystems 28, serial port 30, keyboard or keypad
32,
speaker 34, microphone 36, a short-range communications subsystem 40, and
any other device subsystems generally designated as 42. The graphics
subsystem 44 interacts with the display 22 and renders graphics or text upon
the
display 22.
[0029] Operating system software 54 and various software applications 58 used
by the microprocessor 38 are, in one example embodiment, stored in a
persistent store such as flash memory 24 or a similar storage element. Those
skilled in the art will appreciate that the operating system 54, software
applications 58, or parts thereof may be temporarily loaded into a volatile
store
such as RAM 26. It is contemplated that received communication signals may
also be stored to RAM 26.
[0030]The microprocessor 38, in addition to its operating system functions,
preferably enables execution of software applications 58 on the device 10. A
predetermined set of software applications 58 which control basic device
operations, including at least data and voice communication applications, for
example, will normally be installed on the device 10 during manufacture. A
typical data communication application may include an electronic messaging
module 56 for allowing a user to receive, read, compose, and send text-based
messages. Further software applications 58 may also be loaded onto the device
through the network 50, an auxiliary I/O subsystem 28, serial port 30, short-
range communications subsystem 40 or any other suitable subsystem 42, and
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installed by a user in the RAM 26 or a non-volatile store for execution by the
microprocessor 38. Such flexibility in application installation increases the
functionality of the device and may provide enhanced on-device functions,
communication-related functions, or both. For example, secure communication
applications may enable electronic commerce functions and other such financial
transactions to be performed using the device 10.
[0031] In a data communication mode, a received signal such as a text message
or web page download will be processed by the communication subsystem 11
and input to the microprocessor 38, which will preferably further process the
received signal for output to the display 22 through the graphics subsystem
44,
or alternatively to an auxiliary I/O device 28. A user of device 10 may also
compose data items within a software application 58, such as email messages,
for example, using the keyboard 32 in conjunction with the display 22 and
possibly an auxiliary I/O device 28. Such composed items may then be
transmitted over a communication network through the communication
subsystem 11.
[0032]The serial port 30 in Figure 1 would normally be implemented in a
personal digital assistant (PDA)-type communication device for which
synchronization with a user's desktop computer (not shown) may be desirable,
but is an optional device component. Such a port 30 would enable a user to set
preferences through an external device or software application and would
extend
the capabilities of the device 10 by providing for information or software
downloads to the device 10 other than through a wireless communication
network.
[0033]A short-range communications subsystem 40 is a further component
which may provide for communication between the device 10 and different
systems or devices, which need not necessarily be similar devices. For
example,
the subsystem 40 may include an infrared device and associated circuits and
components or a BluetoothTM communication module to provide for
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communication with similarly enabled systems and devices. The device 10 may
be a handheld device.
[0034] Wireless mobile network 50 is, in an example embodiment, a wireless
packet data network, (e.g., MobitexTM or DataTACTM), which provides radio
coverage to mobile devices 10. Wireless mobile network 50 may also be a voice
and data network such as GSM (Global System for Mobile Communication) and
GPRS (General Packet Radio System), CDMA (Code Division Multiple Access),
or various other third-generation networks such as EDGE (Enhanced Data rates
for GSM Evolution) or UMTS (Universal Mobile Telecommunications Systems).
[0035]The keyboard 32 comprises a reduced-key input device. Accordingly, the
keyboard 32 includes one or more keys that are associated with one or more
symbols. The reduced-key input device is to be distinguished from the
conventional QWERTY device, which includes some keys that have two
associated symbols, such as the number keys and their associated punctuation
or symbolic characters, i.e., the "7" key and the "&" symbol. With a
conventional
QWERTY keyboard, key combinations are used to distinguish between symbols
on the same key. For example, the "7" key is normally associated with the
number 7, unless the "7" key is struck while the SHIFT key is depressed, in
which case the "7" key is associated with the "&" symbol. It will be
understood
that this type of conventional keyboard does not employ multi-tap input. The
keyboard 32 shown in Figure 1 comprises a multi-tap input device.
[0036] In accordance with the present invention, the device 10 includes a
multi-
tap text module 60 for receiving and interpreting input from the keyboard 32.
The multi-tap text module 60 may also provide instructions to the graphics
subsystem 44 regarding the characters or symbols to render on the display 22
based upon the input from the keyboard 32. It will be appreciated that the
multi-
tap text module 60 may interact with or be a part of other software
applications,
including the electronic messaging module 56, so as to enable those
applications
to receive and interpret user input from the keyboard 32. It will also be
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understood that the multi-tap text module 60 may be incorporated as a part of
the operating system 54 for receiving and interpreting input signals from the
keyboard 32 when operating in a multi-tap mode.
[0037] Figure 2 shows an expanded block diagram of the mobile device 10
shown in Figure 1. The microprocessor 38 receives input signals from the
keyboard 32. The input signals are indicative of the keystrokes registered by
the
keyboard 32. The microprocessor 38 also outputs signals to the display 22 for
rendering text on the display 22.
[0038]The multi-tap text module 60 comprises a software application stored in
memory and executed by the microprocessor 38. The device 10 further includes
keystroke timing information 66 and, optionally, a dictionary and grammar
rules
database 64. The keystroke timing information 66 includes data regarding the
timing between certain keystrokes for use by the multi-tap text module 60 in
resolving ambiguities in the multi-tap text input. The keystroke timing
information
66 may include one or more timing values, which are values or thresholds
against which a current keystroke timing interval may be compared, as
described
in greater detail below. The keystroke timing information 66 is stored in
memory
on the device 10 and may be updated from time-to-time by the multi-tap text
module 60.
[0039]The dictionary and grammar rules database 64 may store data regarding
recognized keystroke combinations, probabilities associated with particular
keystroke combinations and the associated text output, and/or grammar
conditions for determining the probabilities attributable to different
possible
outputs for a given keystroke combination. Those of ordinary skill in the art
will
appreciate the range of other data and information that the dictionary and
grammar rules database 64 may store to provide the multi-tap text module 60
with data for resolving certain ambiguities.
[0040] Reference is now made to Figures 6 and 7, which show a front view of
example embodiments of the mobile device 10. In the example embodiments,
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the components and subsystems of mobile device 10 are housed within a hard
plastic main body case 70 that is configured to be held with one or two hands
while the device 10 is in use. The main body case 70 may be a single piece or
may include two or more portions coupled together. For example, in one
embodiment (not shown), the device comprises a "flip-open" device meaning that
the main body case 70 includes two portions hinged together such that the two
portions may be brought into closed contact with one another when the device
is
not in use. The various components of the flip-open device need not be located
in the same portion of the main body case 70.
[0041]The case 70 may include a hook (not shown) so that it can be secured to
a user's belt or pant's top, or it may be used in conjunction with a soft case
(not
shown) that can be mounted to the user's belt or pant's top and into which the
mobile device 10 can be inserted for carrying. Mobile device 10 will typically
be
small enough to fit inside a standard purse or suit jacket pocket. The display
is
visible from the front of the device, as is the reduced-key keypad or
keyboard.
[0042] In the embodiment shown in Figure 6, the device 10 features a typical
telephone keypad 72, wherein most of the numeric keys are associated with
three or more letters. In the embodiment shown in Figure 7, the device 10
features a reduced-key QWERTY keyboard 74 layout, wherein some of the keys
are associated with two or more letters.
[0043] Reference is now made to Figure 3, which shows, in flowchart form, a
method 100 of providing for multi-tap text input. The method 100 is intended
for
use in the context of a system employing a reduced-key input device, such as a
reduced-key QWERTY keyboard or a conventional telephone keypad having
multiple alphabet characters assigned to each key. The system is configured to
operate in a multi-tap mode for a user to specify a first or a second symbol
(or a
third, etc.) associated with a particular key.
[0044] The method 100 begins in step 102, wherein the method 100 evaluates
whether or not a key has been pressed. It will be appreciated that in many
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systems, activating an input key may generate an interrupt signal or other
active
signal to alert the operating system to the fact that a keystroke has been
received. Those of ordinary skill in the art will understand the many
variations
possible for interfacing a keyboard and an operating system.
[0045] While waiting for a keystroke, the method 100 also monitors whether or
not a timeout has occurred in step 104. The timeout is a measure of the time
since the most recent keystroke. If a sufficiently large period of time
elapses,
then the system presumes that the user is finished entering a character and
may
advance the cursor to the next location, as shown in step 106, to await
further
input. In step 106, a "current key" indicator is also cleared. If the timeout
has
not elapsed, then the system maintains the cursor at the present location to
allow the user to re-type the same key, which may indicate that the user wants
to
enter the next symbol associated with the key.
[0046] Note that a timeout count may not necessarily be running. For example,
if
a key has two associated symbols and a user enters the key twice in the multi-
tap mode so as to select the second symbol for output to the display, then the
system outputs the second symbol and advances the cursor. The system need
not then run a timeout count in order to determine whether or not the user is
finished specifying a symbol/character from the selected key. The user has
reached the end of the sequence of possible characters associated with that
key,
so the system may presume that the user is finished selecting a character and
may move to the next cursor location to await further characters. It will be
understood that the conventional timeout count described above is a separate
timing operation from the timing evaluation of the present invention described
below.
[0047] If, in step 102, a keystroke is received, then the method 100 proceeds
to
step 108 where the keystroke is evaluated to determine if the key entered is
the
"next" key. The "next" key may be one or more keys that the user may enter to
indicate he or she is finished entering a multi-tap sequence. For example, the
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"next" key may include an advance arrow key intended to allow the user to
advance the cursor to the adjacent location. If the "next" key has been input,
then in step 110 the cursor is advanced and the method 100 returns to step 102
to await further input; otherwise, the method continues at step 112. Step 110
also involves clearing the "current key" indicator.
[0048] In step 112, the method 100 determines whether the user has entered the
same key as was most recently previously entered. The identity of this key may
be stored as a "current key" indicator. As noted above in connection with
steps
106 and 110, if a timeout occurs or the "next" key is entered, then the
"current
key" indicator is cleared to indicate that the user has moved on to the next
cursor
location. If the user has entered the same key twice in succession, then the
system recognizes that the user may be selecting the second symbol or
character associated with the key.
[0049] If the keystroke is not received from the same key, then the system
proceeds directly to step 116, where a symbol or character associated with the
new key is output. At step 116, there are at least two possible outputs when a
user enters a new key. First, if the cursor has been advanced to the next
location due to, for example, a timeout or a "next" key, then the first symbol
or
character associated with the new key is output. Second, if the new key was
entered prior to the cursor being advanced, then in step 116 the cursor is
first
advanced and then the first symbol or character associated with the new key is
output.
[0050] If, in step 112, it is determined that the keystroke was from the same
key,
then in step 114 the method 100 attempts to resolve any ambiguity associated
with the multi-tap input. In conventional systems, ambiguities are resolved
based upon default rules. For example, in the context of a two-symbol-per-key
system, if a user strikes a key three times, the system presumes that the user
has input the second symbol (two keystrokes) followed by the first symbol (the
third keystroke). To override this default understanding to enter, for
example, the
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first symbol followed by the second symbol, the user must use the "next" key
or
allow a timeout to occur between the first keystroke and the second keystroke.
[0051] In the present invention, at step 114 the method attempts to determine
whether or not the default understanding is correct based upon the relative
timing between the keystrokes. Using the relative timing between keystrokes,
the system selects between a default output and an alternative output. Once
that selection is made, the method 100 proceeds to step 116, where the
selected
output instructions are sent to the display.
[0052] Before returning to step 102 to await further keystrokes, the timeout
counter may be restarted in step 118. At this stage, the "current key"
indicator
may also be set if a new key has been selected.
[0053] It will be appreciated by those of ordinary skill in the art that some
of the
steps or operations described above in connection with the method 100 may be
performed in a different sequence or order without materially altering the
operation of the method 100.
[0054] Reference is now made to Figure 4, which shows, in flowchart form, a
method 200 for resolving ambiguities in multi-tap text input, according to one
embodiment of the present invention. The method 200 describes one
embodiment of an implementation of step 114 from the method 100 shown in
Figure 3.
[0055] The method 200 resolves ambiguities in the context of a two-symbol-per-
key input device and, in particular, resolves ambiguities resulting from
receipt of
three or more keystrokes from the same key. In this context, a typical default
rule is that the first two keystrokes from a selected key indicate the user's
selection of the second symbol associated with the key. The system then
presumes the user is finished entering this character and the cursor is
advanced.
A subsequent keystroke of the same key is considered to be input regarding the
next character. In other words, successive keystrokes are interpreted as
cycling
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through the associated symbols or characters until the end (in this case, the
second symbol) is reached. This end symbol is output and subsequent
keystrokes of the selected key are attributed to user input at the next cursor
position. For example, in the case of a key having the letters E and R
associated
with it, two keystrokes would result in the output of the letter R. Three
keystrokes would result in the output of the letters RE. Four keystrokes would
result in the output of the letters RR. The output of the letters ER requires
three
keystrokes and, conventionally, requires that the default rules for
interpreting
keystrokes be overcome either by use of a "next" key or through a timeout.
[0056]The method 200 begins in step 202, where a keystroke count is
evaluated. This count tracks the number of successive times that a selected
key
has been input. If the keystroke count is three or more, then the method 200
proceeds to step 208. Otherwise, the method 200 continues to step 204.
[0057] In step 204 (i.e., if the keystroke count is two), then the time
elapsed
between the first and second keystroke is used to update a timing value. The
timing value may be solely based upon the time elapsed between the first and
second keystroke or may be partially based upon such time elapsed. Other
factors that may affect the timing value include the keystroke cadence (i.e.,
timing) received earlier in the same session, or stored present timing values.
These various factors may be combined, in one embodiment using weighting
factors, to determine the current timing value.
[0058] In step 206, the output for display is determined based upon the
default
rules. In the present embodiment, the default output upon receipt of the
second
keystroke from a selected key comprises output of the second symbol and
advance of the cursor to the next location in the text field. Following step
206,
the determined output is provided to the graphics subsystem for display on the
display device.
[0059] If the keystroke received is the third (or more) input of the same key,
then
in step 208 the system compares the time between the second keystroke and
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the third keystroke with the timing value. If the time between the second
keystroke and the third keystroke is less than the timing value by a threshold
amount, then the timing of the keystrokes may indicate a need to override the
default output rules. For example, in an embodiment where the timing value is
determined solely by the time between the first keystroke and the second
keystroke, the comparison in step 208 is whether the time between the second
and third keystrokes is less than the time between the first and second
keystrokes by a threshold amount (which may be set to zero in some cases). If
so, then it indicates that the user entered the second and third keystroke in
closer succession than the user entered the first and second keystroke. The
greater pause between the first and second keystroke may indicate that the
user
intends to output the first symbol followed by the second symbol, instead of
the
second followed by the first.
[0060] If the comparison indicates that the default rules should be
overridden,
then the method 200 continues in step 210, where an alternative output is
selected. The alternative output in this case would involve moving the cursor
back a location, changing the second symbol that would have been output
previously (in step 206 following the second keystroke) to the first symbol,
and
then outputting the second symbol in the next location, followed by a cursor
advance. If the comparison does not indicate that the default rules should be
overridden, then the method 200 continues to step 112, where the default
output,
i.e., the first symbol, is selected as the output.
[0061] It will be appreciated that the timing value and the comparison between
the timing value and the time elapsed between the second and third keystrokes
is intended as an evaluation of the user's keystroke cadence. The relative
length
of the pauses between successive keystrokes of the same key may provide an
indication of whether the user intends the keystrokes to trigger a multi-tap
cycling
of symbols associated with the key or whether the user intends the keystrokes
to
be separate. In this manner, the user may override the default multi-tap
output
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rules based upon the timing (i.e., cadence) of his or her keystrokes, without
the
necessity of using a "next" key or waiting for a timeout to occur.
[0062]Those of ordinary skill in the art will therefore understand that the
comparison may evaluate the pause between the second and third keystrokes in
comparison with the pause between the first and second keystrokes, or it may
evaluate it in comparison with other keystrokes. In other words, as described
above, the timing value may be adjusted over time as the user types various
characters. The timing value may be continually adjusted as the user enters
text
into a particular text field in order to "learn" the user's unique keystroke
cadence.
The timing value may also comprise two timing values, one based upon the time
between successive strokes of the same keys and one based upon the timing
between strokes of different keys. The relative timing values developed in
this
manner may be used in the comparison step to determine whether a particular
pause is indicative of a multi-tap input or separate character input. An
excessive
delay between keystrokes may be disregarded in updating the timing values on
the basis that the user has likely interrupted his or her natural keystroke
cadence
to give some thought to the next character or word.
[0063] In an embodiment wherein the timing value is developed or learned as
the
user inputs a set of letters/characters, i.e., over the course of a "session"
or
during text entry in an active text field, the timing value may be used to
disambiguate other multi-tap input cases. For example, when a user inputs a
selected key twice, the user may intend that the second symbol be output to
the
display, which is the default understanding. Alternatively, the user may
intend for
the first symbol to be output twice.
[0064] Reference is now made to Figure 5, which shows a method 300 for
resolving ambiguities in multi-tap text input, according to another embodiment
of
the present invention. The method 300 describes a variation of the method 200
shown in Figure 4.
[0065]The method 300 begins in step 302 with an evaluation of the keystroke
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count. If the keystroke is the second successive keystroke of the selected
key,
then the method 300 proceeds to step 314, where the system compares the
timing between the first and second keystrokes with a stored timing value.
Based upon this comparison, the system determines whether the first and
second keystrokes are indicative of multi-tap input or are separate inputs.
This
comparison may, for example, involve determining whether the delay between
the first and second keystrokes is greater than the timing value by a
threshold
amount. If so, the large delay may be indicative of separate inputs, and the
method 200 may continue at step 316.
[0066] In step 316, the system overrides the default rule of second symbol
output
with an output of two successive first symbols. In the case where the first
symbol has already been output to the display once, then the specific output
instructions developed at step 316 may include advancing the cursor and
outputting the first symbol associated with the selected key.
[0067] If it is determined in step 314 that the timing between the first and
second
keystrokes is not indicative of separate inputs, then the system treats the
second
keystroke as part of a multi-tap input and proceeds to steps 304 and 306.
[0068] Those of ordinary skill in the art will appreciate that the present
invention
is not limited to embodiments employing a reduced-key input device having only
two symbols per key. It may also be employed in resolving ambiguities in multi-
tap systems having three or more symbols per key, such as mobile telephones
using text messaging technology.
[0069] In yet another embodiment, the timing-based evaluation of whether to
override the default rules for interpreting multi-tap text input is subject to
a
linguistics-based evaluation of candidate results. In this embodiment, the
multi-
tap text module 60 (Fig. 1) employs predictive algorithms to enhance the
ability
to interpret multi-tap input ambiguities. Accordingly, if a user provides the
device
(Fig. 1) with three successive keystrokes of the key "ER", the multi-tap text
module 60 may evaluate the candidate results based upon the probability
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information found in the dictionary and grammar rules database 64 (Fig. 2).
The
candidate results include ER, RE, and EEE. The preceding letters typed by the
user may help resolve this ambiguity. For example, if the user typed "A" and
then hit the "ER" key three times, the multi-tap text module 60 would evaluate
the likelihood that the user intended to type AER, ARE, or AEEE. The result
ARE is the most likely result as it is a common word. Accordingly, the multi-
tap
text module 60 may set the output to be RE. However, the letters AER
constitute
a prefix to less common words, such as AEROPLANE. Accordingly, the multi-tap
text module 60 may provide the user with a selection list containing
alternatives if
the user intended something other than the most likely result.
[0070]The linguistics-based approach to resolving ambiguities in multi-tap
text
input may be used to supplement the keystroke timing-based approach. In such
an embodiment, the keystroke timing-based approach described above may
produce a decision on whether to apply the default rules or output an
alternative
result. These two candidate outputs may be checked using linguistic rules to
assess the likelihood of either being correct. If the linguistic rules confirm
the
result from the timing-based approach, then the device 10 may output the
result.
If the linguistic rules conflict with the result arrived at using the timing-
based
approach, the result may be output with a selection list of alternatives in
case the
result is inaccurate.
[0071]Those of ordinary skill in the art will appreciate that a variety of
linguistic-
based predictive algorithms may be employed to varying degrees to determine
the probability that one result is more likely to be correct than another.
These
algorithms may be combined in a variety of manners with keystroke timing
results to improve the accuracy of the multi-tap text module 60 in resolving
ambiguities. In one embodiment, the keystroke timing results and the
linguistic-
based testing are combined to determine the probability that an alternative
output was intended. The device 10 displays the alternative output if the
probability exceeds a predetermined threshold.
CA 02569103 2011-02-23
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[0072] It will also be appreciated that a selection list may be output to the
display
screen in other contexts. In general, a selection list showing alternative
outputs
may be displayed for the user any time that an ambiguity exists regarding two
or
more possible interpretations of the user input. For example, when the user
inputs two of the same keystrokes and the default rule is that the second
symbol
is displayed, a selection list may be provided showing two first symbols as an
alternative output. In another example, the present invention may determine
based upon the keystroke timing that the user intended two first symbols and
may override the default rule to send this output to the display. A selection
list
containing the default output of one second symbol may be output as well so as
to allow the user to select the second symbol if, despite the keystroke
timing, he
or she intended to select the second symbol. Other situations in which a
selection list may be output will be apparent to those of ordinary skill in
the art in
view of the foregoing description.
[0073] The present invention may be embodied in other specific forms without
departing from the spirit or essential characteristics thereof. Certain
adaptations
and modifications of the invention will be obvious to those skilled in the
art.
Therefore, the above discussed embodiments are considered to be illustrative
and not restrictive, the scope of the invention being indicated by the
appended
claims rather than the foregoing description, and all changes which come
within
the meaning and range of equivalency of the claims are therefore intended to
be
embraced therein.
