Abstract: A piezo-electric actuator on the side of a mobile device will enable pressure exerted by the user to be sensed at the conventional button locations, while providing a haptic feedback. Unfortunately, mechanical integration of piezo-electric actuators at the side of a mobile device is challenging. A mobile device in accordance with the present disclosure comprises a PCB; an outer frame surrounding the PCB; and a switch. The switch comprises: a first piezo-electric actuator configured to generate a first actuator voltage signal in response to a first force applied by a user, and to generate a first haptic feedback to the user in response to a first haptic voltage signal transmitted from the controller thereto; and a first virtual button in the outer frame configured to transmit the first force to the first piezo-electric actuator, and to transmit the first haptic feedback to the user.

Abstract: A gesture detection system comprising a virtual button structure for mounting in an outer frame of a mobile device for detecting finger gestures by a user. First and second piezo-electric actuators are in contact with the virtual button structure, and configured to generate first and second varying electrical signals, respectively in response to a dynamic force application to the virtual button structure. A processor is configured to execute instructions stored in memory to i) determine a magnitude and a position of the dynamic force application on the virtual button structure over time, based on the first varying electrical signal and the second varying electrical signal, ii) determine a gesture corresponding to the magnitude and the position of the dynamic force application over time; and iii) provide a response signal based on the gesture.

Abstract: Typically, the displacement of piezo-electric actuators is quite small. Accordingly, some sort of amplification may be needed for specific applications to amplify the displacement of the piezo-electric actuator, and thereby amplify the haptic feedback. For all solutions, the goal is to amplify the displacement of a moveable mass in order to increase vibration to improve the haptic feedback. If the host device is a wearable or portable device, e.g. a smart watch, it would be preferable to excite a heavy moveable mass that is already part of the assembly to harvest enough energy to transmit to the interface with the user. If the device is a large display, e.g. a display in a vehicle info system, the display itself could be the moveable mass.

Abstract: In a driver for a piezo-electric transducer, when a converter circuit and a sensing circuit are the same circuit, many limitations exist on the accuracy of the sensing, due to multiple parasitic effects arising from the interconnection of the power devices. These limitations may limit viability of the sensing for many applications, in particular an accurate determination of when the force on the piezo-electric transducer is fully removed. Providing an additional switch in the sensing circuit configured to repeatedly zero the sensed voltage across the piezo-electric transducer each time the sensed voltage reaches a threshold voltage generates a plurality of voltage segments between zero and the threshold voltage. Accordingly, a controller may then be configured to generate a digital reconstruction of the sensed voltage across the piezo-electric transducer by adding the plurality of voltage segments.

Abstract: A piezo-electric actuator on the side of a mobile device will enable pressure exerted by the user to be sensed at the conventional button locations, while providing a haptic feedback. Unfortunately, mechanical integration of piezo-electric actuators at the side of a mobile device is challenging. A mobile device in accordance with the present disclosure comprises a PCB; an outer frame surrounding the PCB; and a switch. The switch comprises: a first piezo-electric actuator configured to generate a first actuator voltage signal in response to a first force applied by a user, and to generate a first haptic feedback to the user in response to a first haptic voltage signal transmitted from the controller thereto; and a first virtual button in the outer frame configured to transmit the first force to the first piezo-electric actuator, and to transmit the first haptic feedback to the user.

Abstract: Piezoelectric elements are attractive for systems in which both sensing and actuating is required because a single element, i.e. the piezoelectric actuator, can be used that act as both a sensor and an actuator. In conventional systems combining both actuating and sensing functionality, active circuitry is required to read the sensor, and that circuitry requires static and/or dynamic current from a few microamps to a few milliamps. In systems where buttons are used a few times a day, this requirement for current leads to a significant amount of wasted power. Accordingly, a wake-up circuit is provided that does not draw power when no force is applied to the piezoelectric actuator but is capable of detecting pressure applied to the piezo actuator, generate a power-up signal to the actuating circuit, and initiate a haptic feedback with low-latency.

Abstract: In a driver for a piezo-electric transducer, when a converter circuit and a sensing circuit are the same circuit, many limitations exist on the accuracy of the sensing, due to multiple parasitic effects arising from the interconnection of the power devices. These limitations may limit viability of the sensing for many applications, in particular an accurate determination of when the force on the piezo-electric transducer is fully removed. Providing an additional switch in the sensing circuit configured to repeatedly zero the sensed voltage across the piezo-electric transducer each time the sensed voltage reaches a threshold voltage generates a plurality of voltage segments between zero and the threshold voltage. Accordingly, a controller may then be configured to generate a digital reconstruction of the sensed voltage across the piezo-electric transducer by adding the plurality of voltage segments.

Abstract: Mechanical micro-switches, such as the power button, and the volume up and down buttons, in the sidewalls of a smart device's frame remain the weak points in terms of reliability. To overcome this shortcoming a transducer, such as a piezoelectric transducer is placed against the sidewall, and at least one micro-slit is configured in the sidewall forming a flap deflectable into the frame. The micro-slits and the flap enable a displacement in a portion of the sidewall in an otherwise very stiff frame that is large enough to be detected by the transducer when a force is applied by the user and a displacement large enough to be sensed by the user, but not too large so as to risk damage of the transducer or other electronic components inside the frame.