Electronic device including tactile touch-sensitive display and method of controlling same

A method of controlling an electronic device having a touch-sensitive display includes imparting, by an actuator, a force on the touch-sensitive display to provide tactile feedback, determining the force applied by the actuator on the touch-sensitive display, and adjusting a subsequent force imparted by the actuator based on the determined force.

FIELD OF TECHNOLOGY

The present disclosure relates to portable electronic devices that include a touch-sensitive display and the provision of tactile feedback for such devices.

BACKGROUND

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.

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.

Improvements in provision and control of tactile feedback in touch-sensitive devices are desirable.

DETAILED DESCRIPTION

A method of controlling an electronic device having a touch-sensitive display includes imparting, by an actuator, a force on the touch-sensitive display to provide tactile feedback, determining the force applied by the actuator on the touch-sensitive display, and adjusting a subsequent force imparted by the actuator based on the determined force.

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.

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, phones, personal organizers, PDAs, notebook computers, and the like. The portable electronic device may also be a portable electronic device without wireless communication capabilities.

The force applied by the actuator or actuators on the touch-sensitive display may be adjusted by adjusting the applied voltage or current to compensate for changes over time and with use of the portable electronic device. Factors such as battery voltage and temperature, that may change force applied by a piezo actuator 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 response and reduces the chance of input errors such as double entry, decreasing use time and increasing user-satisfaction.

A block diagram of an example portable electronic device100is shown inFIG. 1. The portable electronic device100includes multiple components, such as a processor102that controls the overall operation of the portable electronic device100. Communication functions, including data and voice communications, are performed through a communication subsystem104. Data received by the portable electronic device100is decompressed and decrypted by a decoder106. The communication subsystem104receives messages from and sends messages to a wireless network150. The wireless network150may 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 source142, such as one or more rechargeable batteries or a port to another power supply, powers the portable electronic device100.

The processor102interacts with other devices, such as a Random Access Memory (RAM)108, memory110, a display112with a touch-sensitive overlay114operably connected to an electronic controller116that together comprise a touch-sensitive display118, one or more actuators120, one or more force sensors122, an auxiliary input/output (I/O) subsystem124, a data port126, a speaker128, a microphone130, short-range communications132and other device subsystems134. User-interaction with a graphical user interface is performed through the touch-sensitive overlay114. The processor102interacts with the touch-sensitive overlay114via the electronic controller116. Information, such as text, characters, symbols, images, icons, and other items that may be displayed or rendered on a portable electronic device, is displayed on the touch-sensitive display118via the processor102. The processor102may also interact with an accelerometer136that may be utilized to detect direction of gravitational forces or gravity-induced reaction forces.

To identify a subscriber for network access, the portable electronic device100uses a Subscriber Identity Module or a Removable User Identity Module (SIM/RUIM) card138for communication with a network, such as the wireless network150. Alternatively, user identification information may be programmed into the memory110.

The portable electronic device100also includes an operating system146and software programs or components148that are executed by the processor102and are typically stored in a persistent, updatable store such as the memory110. Additional applications or programs may be loaded onto the portable electronic device100through the wireless network150, the auxiliary I/O subsystem124, the data port126, the short-range communications subsystem132, or any other suitable subsystem134.

A received signal such as a text message, an e-mail message, or web page download is processed by the communication subsystem104and input to the processor102. The processor102processes the received signal for output to the display112and/or to the auxiliary I/O subsystem124. A subscriber may generate data items, for example e-mail messages, which may be transmitted over the wireless network150through the communication subsystem104. For voice communications, the overall operation of the portable electronic device100is similar. The speaker128outputs audible information converted from electrical signals, and the microphone130converts audible information into electrical signals for processing.

The touch-sensitive display118may 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 display112and a capacitive touch-sensitive overlay114. The overlay114may be an assembly of multiple layers in a stack including, for example, a substrate, LCD display112, 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).

One or more touches, also known as touch contacts or touch events, may be detected by the touch-sensitive display118and processed by the controller116, for example, to determine a location of a touch. Touch location data may include a single point of contact, such as a point at or near a center of the area of contact, or the entire area of contact for further processing. The location of a touch detected on the touch-sensitive display118may include x and y components, e.g., horizontal and vertical with respect to one's view of the touch-sensitive display118, respectively. For example, the x component may be determined by a signal generated from one touch sensor layer, and the y component may be determined by a signal generated from another touch sensor layer. A signal is provided to the controller116in response to detection of a suitable object, such as a finger, thumb, or other items, for example, a stylus, pen, or other pointer, depending on the nature of the touch-sensitive display118. More than one simultaneous location of contact may occur and be detected.

The actuator120may comprise one or more piezoelectric (piezo) actuators that provide tactile feedback.FIG. 2Ais front view of an example of a portable electronic device100. In the example shown inFIG. 2A, the actuator120comprises four piezo actuators120, each located near a respective corner of the touch-sensitive display118.FIG. 2Bis a sectional side view of the portable electronic device100through the line202ofFIG. 2AandFIG. 2Cis a side view of a piezo actuator120ofFIG. 2B.

Each piezo actuator120is supported on a respective support ring212that extends from a base214within a housing216of the portable electronic device100. The base214may be any suitable base and may include, for example, a printed circuit board or flex circuit board supported by a stiff support between the base214and a back of the housing216. The housing216may be any suitable housing for the internal components shown inFIG. 1and for sealing with and facilitating movement of the touch-sensitive display118when an externally applied force is received on the touch-sensitive display118or when a force is applied by the piezo actuators120on the touch-sensitive display. In the present example, the accelerometer136is positioned on the base214and is arranged to detect displacement of the base214and is thereby utilized to determine the force on the base214.

The support rings212extend from the base214such that contraction of the piezo actuators120results in an applied force against the touch-sensitive display118, opposing a force externally applied to the touch-sensitive display118. Each piezo actuator120includes a piezoelectric device, such as a piezoelectric (PZT) ceramic disk206adhered to a metal substrate208. A shock-absorbing element210of, for example, hard rubber is located between the PZT disk206and the touch-sensitive display118. In the present example, four force sensors122are utilized, with each force sensor122located between a respective shock absorbing element210and metal substrate208. Depression of the touch-sensitive display118by user application of a force thereto is determined by a change in resistance at the force sensors122.

The metal substrate208bends when the PZT disk206contracts diametrically due to build up of charge at the PZT disk206or in response to an external force applied to the touch-sensitive display118. The charge may be adjusted by varying the applied voltage or current, thereby controlling the force applied by the piezo actuators120on the touch-sensitive display118. The charge on the piezo actuators120may be removed by a controlled discharge current that causes the PZT disk206to expand diametrically, decreasing the force applied by the piezo actuators120on the touch-sensitive display118. Absent an external force applied to the overlay114and absent a charge on the PZT disk206, the piezo actuator120may be slightly bent due to a mechanical preload.

FIG. 3shows a functional block diagram of components of the portable electronic device100. In this example, each force sensor122is connected to a controller302, which includes an amplifier and analog-to-digital converter (ADC). The force sensors122may be force sensing resistors in an electrical circuit and therefore the resistance changes with force applied to the force sensors122. As applied force on the touch-sensitive display118increases, the resistance decreases. This change is determined via the controller116for each of the force sensors122, and with calibrated force sensors122, with known gain and offset values, the corresponding value of the force at each of the force sensors122is determined.

The piezo actuators120are connected to a piezo driver304that communicates with the controller302. The controller302is also in communication with the main processor102of the portable electronic device100and may receive and provide signals to the main processor102. The piezo driver304may optionally be embodied in drive circuitry between the controller302and the piezoelectric disks312. The controller302controls the piezo driver304that controls the current to the PZT disks206and thus controls the charge and the force applied by the piezo actuators120on the touch-sensitive display118. Each of the PZT disks206may be controlled substantially equally and concurrently. Optionally, the PZT disks206may be controlled separately. When an applied force, on the touch-sensitive display118, exceeds a threshold, the charge at the piezo actuators120is modulated to impart a force on the touch-sensitive display to simulate collapse of a dome switch. When the applied force, on the touch-sensitive display118falls below a low threshold, after actuation of the piezo actuators120, the charge at the piezo actuators120is modulated to impart a force, by the piezo actuators120, to simulate release of a dome switch or similar haptics feedback mechanism.

The mechanical work performed by the piezo actuators120may be controlled to provide generally consistent force and movement of the touch-sensitive display118in response to detection of an applied force on the touch-sensitive display118in the form of a touch, for example. Fluctuations in mechanical work performed as a result of, for example, temperature, may be reduced by modulating the current to control the charge.

A flowchart illustrating a method of controlling an electronic device to provide tactile feedback is shown inFIG. 4. The method is advantageously performed by the processor102and the controller302performing stored instructions from a computer-readable medium. 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.

When a touch is detected402, the location of touch on the touch-sensitive display118is determined. The force of the touch is determined404based on signals from the force sensors122. A determination is made406whether or not the force of the touch is above a first threshold and, if so, the charge at the piezo actuators120is modulated408to simulate collapse of a dome switch. When a determination is made406that the force of the touch is not above the first threshold, the process continues at404to determine the force of the touch. After modulating the charge at the piezo actuators120at408, the force of the touch is determined410and a determination is made if the force has dropped below a second threshold that is lower than the first threshold. If a determination is made410that the force is below the second threshold, the charge at the piezo actuators120is modulated to simulate release414of the dome switch.

A simplified example of a graph of voltage across the PZT disks206versus time is shown inFIG. 5. The voltage shown is the voltage across one of the PZT disks206, which is related to the charge. The touch is detected at the point500. The externally applied force on the touch-sensitive display118exceeds the threshold at502and the charge at the PZT disk206is modulated between the points502,504to ramp up the charge over a period of time that is sufficiently long to inhibit user detection of the force. The charge on the PZT disk206is 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 the points504,506. When the externally applied force on the touch-sensitive display118falls below the low threshold, the charge at the PZT disk206is modulated to impart a force, by the piezo actuators120, to increase the charge over a relatively short period of time to simulate release of a dome switch between the points508,510. The charge on the PZT disk206is removed to reduce the applied force by the piezo actuators120over a longer period of time between the points510,512.

The force applied by the piezo actuators120on the touch-sensitive display118may change over time and with use of the portable electronic device100. Factors such as battery voltage and temperature may affect the force applied by the piezo actuators120on the touch-sensitive display118, therefore changing the tactile feel. The force applied by the piezo actuators120may be adjusted during use of the device to compensate for changes by adjusting the applied voltage or current.

FIG. 6is a flow chart illustrating a method of controlling the portable electronic device100to adjust the force applied by the piezo actuators120. The method ofFIG. 6may be carried out by, for example, by the processor102or the controller302or both the processor102and the controller302executing 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.

As shown, when the charge at the piezo actuators120is modulated to simulate collapse or release of a dome switch at602, the force applied by the piezo actuators120is determined. The force applied by the piezo actuators120is determined604based on the force measured utilizing the accelerometer136and the force determined utilizing the force sensors122. The force measured utilizing the accelerometer136is a force at the base214of the portable electronic device100and is a result of forces transmitted to the base214through the piezo actuators120. This force includes the force applied by the touch on the touch-sensitive display118and the force applied by the piezo actuators120on the touch-sensitive display118. The force applied by the touch on the touch-sensitive display118is known from the force determined utilizing force sensors122. The force applied by the piezo actuators120is determined by subtracting the force determined utilizing the force sensors122from the force determined utilizing the accelerometer136. The force applied by the piezo actuators120, that is determined at604, is then compared to a target force. When a determination is made606that the force applied by the piezo actuators120is greater than the target force, the voltage or current for modulating the charge at the piezo actuators120is reduced608so that the force applied by the piezo actuators120for a subsequent touch is closer to the target force. When the force applied by the piezo actuators120is not greater than the target force, a determination is made610whether or not the force is less than the target force. When a determination is made610that the force applied by the piezo actuators120is less than the target force, the voltage or current for modulating the charge at the piezo actuators120is increased612so that the force applied by the piezo actuators120for a subsequent touch is closer to the target force.

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 actuators120and 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 actuators120and the ramp-up slope, without changing 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.

The target force may be pre-set during manufacture of the portable electronic device100or may be selectable to provide a desired tactile feedback. The applied voltage or current is adjusted based on the force applied by the piezo actuators120on the touch-sensitive display118, facilitating the provision of generally consistent tactile feedback.

In the example described above with reference toFIG. 6, the forces applied by the piezo actuators604are determined during tactile feedback to simulate collapse and release of a dome switch when a touch is received on the touch-sensitive display118. The forces applied by the piezo actuators604may also be determined, for example, during a vibration notification at the portable electronic device100, when the piezo actuators604are also utilized to provide vibration. In this case, the force applied by the piezo actuators may be determined utilizing the accelerometer136and the force from a touch is not subtracted. The target force for vibration may be different than for simulation of collapse and release of a dome switch. Forces applied by the piezo actuators120for vibration may be adjusted in a similar manner using the different target force.

In the examples described herein, the accelerometer136is positioned on the base214and is arranged to detect displacement of the base214and determine the force on the base214. Alternatively, any other suitable force sensor or force sensors may be utilized.

A method of controlling an electronic device having a touch-sensitive display includes imparting, by an actuator, a force on the touch-sensitive display to provide tactile feedback, determining the force applied by the actuator on the touch-sensitive display, and adjusting a subsequent force imparted by the actuator based on the determined force.

A computer-readable medium has computer-readable code embodied therein for execution by a processor in an electronic device to cause the electronic device to carry out the above method.

An electronic device includes a base, a touch-sensitive display moveable relative to the base, an actuator arranged to impart a force on the touch-sensitive display, an accelerometer and a processor operably coupled to the touch-sensitive display, the actuator and the accelerometer to determine, based on signals from the accelerometer, a force applied by the actuator on the touch-sensitive display and to adjust a subsequent force applied by the actuator based on the force determined at the processor.

Advantageously, the force applied by the piezo actuators120on the touch-sensitive display118may be adjusted by adjusting the applied voltage or current to compensate for changes over time and with use of the portable electronic device100. 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 response and reducing the chance of input errors such as double entry, decreasing use time and increasing user-satisfaction.

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.