Note: Descriptions are shown in the official language in which they were submitted.
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ELECTRONIC DEVICE INCLUDING TACTILE TOUCH-SENSITIVE DISPLAY AND
METHOD OF CONTROLLING SAME
FIELD OF TECHNOLOGY
[0001] The present disclosure relates to portable electronic devices that
include a touch-
sensitive display and the provision of tactile feedback for such devices.
BACKGROUND
[0002] Electronic devices, including portable electronic devices, have gained
widespread
use and may provide a variety of functions including, for example, telephonic,
electronic text
messaging and other personal information manager (PIM) application functions.
Portable
electronic devices can include several types of devices including mobile
stations such as
cellular phones, smart phones, Personal Digital Assistants (PDAs), and laptop
computers.
Touch-sensitive input devices are useful for input on a portable electronic
device.
[0003] Devices such as PDAs or smart phones are generally intended for
handheld use
and ease of portability. Smaller devices are generally desirable for
portability. Touch screen
devices constructed of a display, such as a liquid crystal display (LCD), with
a touch-sensitive
overlay are useful on such handheld devices as such handheld devices are small
and are
therefore limited in space available for user input and output devices.
Further, the screen
content on the touch screen devices can be modified depending on the functions
and
operations being performed.
[0004] Improvements in provision and control of tactile feedback in touch-
sensitive
devices are desirable.
SUMMARY
[0005] According to one aspect, a method of controlling an electronic device
that has a
touch-sensitive display is provided. The method includes determining a first
value
representative of force applied by an actuator to a touch-sensitive input
device of an
electronic device, controlling the actuator to modulate the force on the touch-
sensitive input
device for providing tactile feedback, determining a second value
representative of force
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applied by the actuator to the touch-sensitive input device, and adjusting
control of the
actuator to adjust a subsequent force applied by the actuator based on a
difference between
the first value and the second value.
[0006] According to another aspect, a computer-readable medium has computer-
readable code embodied therein for execution by at least one processor in an
electronic
device to cause the electronic device to carry out the above method.
[0007] According to another aspect, an electronic device includes a base, a
touch-
sensitive display moveable relative to the base, an actuator arranged to
modulate a force on
the touch-sensitive display, a force sensor arranged to determine values of
force, applied by
the actuator, on the touch-sensitive display, and a processor operably coupled
to the touch-
sensitive display, the actuator and the force sensor to determine a first
value representative
of force applied by the actuator to the touch-sensitive display, control the
actuator to
modulate the force on the touch-sensitive display, determine a second value
representative
of force applied by the actuator to the touch-sensitive display, and adjust
control of the
actuator to adjust a subsequent force applied by the actuator based on a
difference between
the first value and the second value.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Embodiments of the present disclosure will now be described, by way of
example
only, with reference to the attached Figures, in which:
[0009] FIG. 1 is a block diagram of an example portable electronic device in
accordance
with the present disclosure;
[0010] FIG. 2 is a front view of an example of a portable electronic device in
accordance
with the present disclosure;
[0011] FIG. 3 is a sectional side view of the example portable electronic
device through
the line 202 of FIG. 2A, in accordance with the present disclosure;
[0012] FIG. 4 is a functional block diagram showing components of the example
portable
electronic device in accordance with the present disclosure;
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[0013] FIG. 5 is a flowchart illustrating a method of controlling a portable
electronic
device to provide tactile feedback in accordance with the present disclosure;
[0014] FIG. 6 is an example of a graph of voltage across a piezo actuator
versus time
during actuation in accordance with the present disclosure; and
[0015] FIG. 7 is a flowchart illustrating a method of controlling an
electronic in
accordance with the present disclosure.
DETAILED DESCRIPTION
[0016] A method of controlling an electronic device includes determining a
first value
representative of force applied by an actuator to a touch-sensitive input
device of an
electronic device, controlling the actuator to modulate the force on the touch-
sensitive input
device for providing tactile feedback, determining a second value
representative of force
applied by the actuator to the touch-sensitive input device, and adjusting
control of the
actuator to adjust a subsequent force applied by the actuator based on a
difference between
the first value and the second value.
[0017] For simplicity and clarity of illustration, reference numerals may be
repeated
among the figures to indicate corresponding or analogous elements. Numerous
specific
details are set forth to provide a thorough understanding of the embodiments
described
herein. The embodiments may be practiced without these specific details. In
other
instances, well-known methods, procedures, and components have not been
described in
detail so as not to obscure the embodiments described herein. The description
is not to be
considered as limited to the scope of the embodiments described herein.
[0018] The disclosure generally relates to an electronic device, which in the
embodiments described herein is a portable electronic device. Examples of
portable
electronic devices include mobile, or handheld, wireless communication devices
such as
pagers, cellular phones, cellular smart-phones, wireless organizers, personal
digital
assistants, wirelessly enabled notebook computers, and the like. The portable
electronic
device may also be a portable electronic device without wireless communication
capabilities
such as a handheld electronic game device, digital photograph album, digital
camera, or
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other device.
[0019] A block diagram of an example of a portable electronic device 100 is
shown in
FIG. 1. The portable electronic device 100 includes multiple components, such
as a
processor 102 that controls the overall operation of the portable electronic
device 100.
Communication functions, including data and voice communications, are
performed through
a communication subsystem 104. Data received by the portable electronic device
100 is
decompressed and decrypted by a decoder 106. The communication subsystem 104
receives messages from and sends messages to a wireless network 150. The
wireless
network 150 may be any type of wireless network, including, but not limited
to, data wireless
networks, voice wireless networks, and dual-mode networks that support both
voice and data
communications. A power source 142, such as one or more rechargeable batteries
or a port
to another power supply, powers the portable electronic device 100.
[0020] The processor 102 interacts with other devices, such as a Random Access
Memory (RAM) 108, memory 110, a display 112 with a touch-sensitive overlay 114
operably
connected to an electronic controller 116 that together comprise a touch-
sensitive display
118, one or more actuators 120, one or more force sensors 122, an auxiliary
input/output
(I/O) subsystem 124, a data port 126, a speaker 128, a microphone 130, short-
range
communications 132 and other device subsystems 134. User-interaction with a
graphical
user interface is performed through the touch-sensitive overlay 114. The
processor 102
interacts with the touch-sensitive overlay 114 via the electronic controller
116. Information,
such as text, characters, symbols, images, icons, links, and other items that
may be
displayed or rendered on a portable electronic device, is displayed on the
touch-sensitive
display 118 via the processor 102. The processor 102 may also interact with an
accelerometer 136 that may be utilized to detect direction of gravitational
forces or gravity-
induced reaction forces.
[0021] To identify a subscriber for network access, the portable electronic
device 100
uses a Subscriber Identity Module or a Removable User Identity Module
(SIM/RUIM) card
138 for communication with a network, such as the wireless network 150.
Alternatively, user
identification information may be programmed into the memory 110.
[0022] The portable electronic device 100 also includes an operating system
146 and
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software programs or components 148 that are executed by the processor 102 and
are
typically stored in a persistent, updatable store such as the memory 110.
Additional
applications or programs may be loaded onto the portable electronic device 100
through the
wireless network 150, the auxiliary I/O subsystem 124, the data port 126, the
short-range
communications subsystem 132, or any other suitable subsystem 134.
[0023] A received signal such as a text message, an e-mail message, or web
page
download is processed by the communication subsystem 104 and input to the
processor
102. The processor 102 processes the received signal for output to the display
112 and/or to
the auxiliary I/O subsystem 124. A subscriber may generate data items, for
example e-mail
messages, which may be transmitted over the wireless network 150 through the
communication subsystem 104. For voice communications, the overall operation
of the
portable electronic device 100 is similar. The speaker 128 outputs audible
information
converted from electrical signals, and the microphone 130 converts audible
information into
electrical signals for processing.
[0024] The touch-sensitive display 118 may be any suitable touch-sensitive
display, such
as a capacitive, resistive, infrared, or surface acoustic wave (SAW) touch-
sensitive display,
as known in the art. A capacitive touch-sensitive display includes the display
112 and a
capacitive touch-sensitive overlay 114. The overlay 114 may be an assembly of
multiple
layers in a stack including, for example, a substrate, LCD display 112, a
ground shield layer,
a barrier layer, one or more capacitive touch sensor layers separated by a
substrate or other
barrier, and a cover. The capacitive touch sensor layers may be any suitable
material, such
as patterned indium tin oxide (ITO).
[0025] One or more touches, also known as touch contacts or touch events, may
be
detected by the touch-sensitive display 118. The processor 102 may determine
attributes of
the touch, including a location of a touch. Touch location data may include an
area of contact
or a single point of contact, such as a point at or near a center of the area
of contact. The
location of a detected touch may include x and y components, e.g., horizontal
and vertical
components, respectively, with respect to one's view of the touch-sensitive
display 118. For
example, the x location component may be determined by a signal generated from
one touch
sensor, and the y location component may be determined by a signal generated
from another
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touch sensor. A signal is provided to the controller 116 in response to
detection of a touch. A
touch may be detected from any suitable object, such as a finger, thumb,
appendage, or
other items, for example, a stylus, pen, or other pointer, depending on the
nature of the
touch-sensitive display 118. Multiple simultaneous touches may be detected.
[0026] The actuator 120 may be depressed by applying sufficient force to the
touch-
sensitive display 118 to overcome the actuation force of the actuator 120. The
actuator 120
may be actuated by pressing anywhere on the touch-sensitive display 118. The
actuator 120
may provide input to the processor 102 when actuated. Actuation of the
actuator 120
provides the user with tactile feedback.
[0027] The actuator 120 may comprise one or more piezoelectric (piezo)
actuators that
provide tactile feedback. FIG. 2 is front view of an example of a portable
electronic device
100. In the example shown in FIG. 2, the actuator 120 comprises four piezo
actuators 120,
each located near a respective corner of the touch-sensitive display 118. FIG.
3 is a
sectional side view of the portable electronic device 100 through the line 202
of FIG 2. Each
piezo actuator 120 is supported within the portable electronic device 100 such
that
contraction of the piezo actuators 120 applies a force against the touch-
sensitive display 118,
opposing a force externally applied to the display 118. Each piezo actuator
120 includes a
piezoelectric device 302, such as a piezoelectric disk adhered to a substrate
304, such as a
metal substrate. An element 306 that is advantageously at least partially
flexible and
comprises, for example, hard rubber may be located between the piezoelectric
device 302
and the touch-sensitive display 118. The element 306 does not substantially
dampen the
force applied to or on the touch-sensitive display 118. In the example shown
in FIG. 2 and
FIG. 3, the force sensor 122 comprises four force sensors 122 located between
the element
306 and the substrate 304. The force sensors 122 are utilized to determine a
value related
to the force at each of the force sensors 122 when an external force is
applied to the touch-
sensitive display 118. Each force sensor 122 may also be utilized to determine
a value
related to force, applied by a respective actuator 120, on the touch-sensitive
display 118.
The substrate 304 bends when the piezoelectric device 302 contracts
diametrically due to
build up of charge at the piezoelectric device 302 or in response to an
external force applied
to the touch-sensitive display 118. The charge may be adjusted by varying the
applied
voltage or current, thereby controlling the force applied by the piezo
actuators 120 on the
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touch-sensitive display 118. The charge on the piezo actuators 120 may be
removed by a
controlled discharge current that causes the piezoelectric devices 302 to
expand
diametrically, decreasing the force applied by the piezo actuators 120 on the
touch-sensitive
display 118. Absent an external force applied to the touch-sensitive display
118 and absent a
charge on the piezoelectric device 302, the piezo actuator 120 may be slightly
bent due to a
mechanical preload.
[0028] A functional block diagram of components of the portable electronic
device 100 is
shown in FIG. 4. In this example, each force sensor 122 is connected to a
controller 402,
which includes an amplifier and analog-to-digital converter (ADC). The force
sensors 122
may be, for example, force-sensing resistors in an electrical circuit such
that the resistance
changes with force applied to the force sensors 122. As applied force on the
touch-sensitive
display 118 increases, the resistance decreases. This change is determined via
the
controller 116 for each of the force sensors 122, and a value representative
of the force at
each of the force sensors 122 is determined.
[0029] The piezo actuators 120 are connected to a piezo driver 404 that
communicates
with the controller 402. The controller 402 is also in communication with the
main processor
102 of the portable electronic device 100 and may receive and provide signals
to and from
the main processor 102. The piezo actuators 120 and the force sensors 122 are
operatively
connected to the main processor 102 via the controller 402. The controller 402
controls the
piezo driver 404 that controls the current/voltage to the piezoelectric
devices 302 and thus
controls the charge and the force applied by the piezo actuators 120 on the
touch-sensitive
display 118. Each of the piezoelectric devices 302 may be controlled
substantially equally
and concurrently. Optionally, the piezoelectric devices 302 may be controlled
separately.
Tactile feedback is provided by controlling the piezoelectric devices 302. For
example, when
an applied force on the touch-sensitive display 118 exceeds a depression
threshold, the
charge at the piezo actuators 120 is modulated to impart a force on the touch-
sensitive
display 118 to simulate depression of a dome switch. When the applied force,
on the touch-
sensitive display 118, falls below a release threshold, after simulation of
depression of a
dome switch, the charge at the piezo actuators 120 is modulated to impart a
force, by the
piezo actuators 120, to simulate release of a dome switch.
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[0030] A flowchart illustrating a method of controlling the electronic device
100 is shown
in FIG. 5. The method may be carried out by software executed by, for example,
the
processor 102 or the controller 402 or both the processor 102 and the
controller 402. Coding
of software for carrying out such a method is within the scope of a person of
ordinary skill in
the art given the present description.
[0031] When a touch is detected 502, the location of touch on the touch-
sensitive display
118 is determined. A value representative of the force of the touch is
determined 504 based
on signals from the force sensors 122. When the value representative of the
force of the
touch is above a first threshold at 506, the charge at the piezo actuators 120
is modulated
508 to simulate collapse of a dome switch. When the value representative of
the force of the
touch is not above the first threshold at 506, the process continues at 504 to
again determine
the value representative of the force of the touch. After modulating the
charge at the piezo
actuators 120 at 508, the value representative of the force of the touch is
determined 510
and when the value representative of the force has fallen below a second
threshold at 512,
the charge at the piezo actuators 120 is modulated 514 to simulate release of
the dome
switch. The second threshold is lower than the first threshold.
[0032] A simplified example of a graph of voltage across the piezoelectric
devices 302
versus time is shown in FIG. 6. The voltage shown is the voltage across one of
the
piezoelectric devices 302, which is related to the charge. The touch is
detected at 600. The
externally applied force on the touch-sensitive display 118 exceeds the
threshold at 602 and
the charge at the piezoelectric device 302 is modulated between 602 and 604 to
ramp up the
charge over a period of time that is sufficiently long to inhibit user
detection of the force. The
charge on the piezoelectric device 302 is removed over a much shorter period
of time
relative to the period of time for ramp up to simulate the collapse of the
dome switch between
604 and 606. When the externally applied force on the touch-sensitive display
118 falls
below the low threshold, the charge at the piezoelectric device 302 is
modulated to impart a
force, by the piezo actuators 120, to increase the charge over a relatively
short period of time
to simulate release of a dome switch between 608 and 610. The charge on the
piezoelectric
device 302 is removed to reduce the applied force by the piezo actuators 120
over a longer
period of time between 610 and 612.
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[0033] The force applied by the piezo actuators 120 on the touch-sensitive
display 118
may change over time and with use of the portable electronic device 100.
Factors such as
battery voltage and temperature may affect the force applied by the piezo
actuators 120 on
the touch-sensitive display 118, therefore changing the tactile feel. The
force applied by the
piezo actuators 120 may be adjusted during use of the device to compensate for
changes by
adjusting the applied voltage or current.
[0034] FIG. 7 is a flow chart illustrating a method of controlling the
portable electronic
device 100 to adjust the force applied by the piezo actuators 120. The method
of FIG. 7 may
be carried out by, for example, the processor 102 or the controller 402 or
both the processor
102 and the controller 402 executing software from a computer-readable medium.
Coding of
software for carrying out such steps is well within the scope of a person of
ordinary skill in the
art given the present description.
[0035] The value representative of force at each of the force sensors is
determined 702.
The actuators are controlled 704 to modulate the force on the touch-sensitive
display 118
and the value representative of force at each of the force sensors is
determined 706. In the
example of the piezoelectric devices 302, the value representative of force
may be
determined at 702 when the piezoelectric devices 302 are not charged and may
be
determined again at 706 when the piezoelectric devices 302 are at the peak of
charge.
Thus, referring to FIG. 6, the value representative of force may be determined
at 602 and
again at 604. Alternatively, the value representative of force may be
determined at 702 when
the piezoelectric devices 302 are charged and may be determined again at 706
after the
piezoelectric devices 302 are discharged. Again referring to FIG. 6, the value
representative
of force may be determined at 604 and again 606. In still another alternative,
the values
representative of forces may be determined during simulation of release of a
dome switch.
[0036] The difference between the value representative of force determined at
702 and
the value representative of force determined at 706 is determined 708 for each
force sensor
122 and therefore the difference between the minimum value representative of
force and
maximum value representative of force is determined for each force sensor 122.
[0037] Each difference in values representative of force that is determined at
708 is
compared to a target value. When a determination is made 710 that the
difference is greater
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than the target value, the voltage or current for modulating the charge at the
piezo actuators
120 is reduced 712 so that the peak charge is reduced, thereby reducing the
maximum force
for a subsequent touch. The reduction in applied voltage or current at 712 may
be related to
the difference between the target value and the difference in values
representative of force.
Thus, a greater difference results in a greater reduction in applied voltage
or current.
Alternatively, the reduction may be a preset increment. When a determination
is made 714
that the difference is less than the target value, the voltage or current for
modulating the
charge at the piezo actuators 120 is increased 716 so that the peak charge is
increased,
thereby increasing the maximum force applied by the piezo actuators 120 for a
subsequent
touch. The increase in applied voltage or current at 716 may be related to the
difference
between the target value and the difference in values representative of force.
Thus, a
greater difference results in a greater reduction in applied voltage or
current. Alternatively,
the increase may be a preset increment.
[0038] The actuators are controlled by modulating the charge at the
piezoelectric devices
302, utilizing the applied voltage or current. The voltage or current may be
reduced for the
ramp up and discharge during simulation of collapse of the dome switch, for
example, by
reducing the peak charge at the piezo actuators 120 and the ramp-up slope
without changing
ramp up time or the discharge time. The voltage or current may also be reduced
for the
charge up and ramp down during simulation of release of the dome switch
without changing
the charge up time. The voltage or current may be increased, for the ramp up
and discharge
during simulation of collapse of the dome switch, for example, by increasing
the peak charge
at the piezo actuators 120 and the ramp-up slope, without changing the ramp up
time or the
discharge time. The voltage or current may also be increased, for the charge
up and ramp
down during simulation of release of the dome switch, without changing the
charge up time.
[0039] The values representative of force as determined at 702 and 706 may
include an
applied force from a touch on the touch-sensitive display 118. The applied
force may
generally be subtracted out by determining the difference in values
representative of force
[0040] The target value may be pre-set during manufacture of the portable
electronic
device 100 or may be selectable to provide a desired tactile feedback. The
applied voltage
or current is adjusted based on the force applied by the piezo actuators 120
on the touch-
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sensitive display 118, facilitating the provision of generally consistent
tactile feedback.
[0041] In the example described above with reference to FIG. 7, the forces
applied by the
piezo actuators 604 are determined during tactile feedback to simulate
collapse and release
of a dome switch when a touch is received on the touch-sensitive display 118.
The forces
applied by the piezo actuators 604 may also be determined, for example, during
a vibration
notification at the portable electronic device 100, when the piezo actuators
120 are also
utilized to provide vibration. In this case, the force applied by the piezo
actuators 120 may
be determined utilizing the force sensors 122. The target value for vibration
may be different
than for simulation of collapse and release of a dome switch. Forces applied
by the piezo
actuators 120 for vibration may be adjusted in a similar manner using the
different target
force.
[0042] Advantageously, the force applied by the piezo actuators 120 on the
touch-
sensitive display 118 may be adjusted by adjusting the applied voltage or
current to
compensate for changes over time and with use of the portable electronic
device 100.
Factors such as battery voltage and temperature, that may change the force
applied to the
touch-sensitive display, may be compensated for to provide desirable tactile
feedback or
confirming receipt of input to the user. This provides a positive, desirable
response and
reduces the chance of input errors such as double entry, decreasing use time
and increasing
user-satisfaction.
[0043] While the embodiments described herein are directed to particular
implementations of the portable electronic device and the method of
controlling the portable
electronic device, it will be understood that modifications and variations may
occur to those
skilled in the art. All such modifications and variations are believed to be
within the sphere
and scope of the present disclosure.
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