Harvard College

Boreas Technologies Inc.

Simon Chaput

Gu-Yeon Wei

Guillaume Chauvette

Martin Renaud

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.

Gesture detection using piezo-electric actuators

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.

High-resolution sensing of piezo-electric transducers

A driver for a circuit with a capacitive load, includes a power converter configured to receive a DC input voltage from an input stage, generate a switching voltage at a switching node, and output an output voltage forming an analog waveform at an output stage. The power converter includes a first switch connected between an inductive device and a ground, a second switch connected between the inductive device and the output stage, and a controller to control the first switch and the second switch. The analog waveform has an amplitude at least two times greater than the input voltage.

Driver for a circuit with a capacitive load

A driver for a circuit with a capacitive load is configured for coupling to a voltage source which provides a DC input voltage, and is configured to generate an output voltage at an output. The driver includes a bidirectional synchronous power converter with a first switch, a second switch, and an inductive device connected to the first and/or second switch. A controller is configured to control the first switch and the second switch. The bidirectional synchronous power converter generates a switching voltage from the input voltage at a switching node and generates the output voltage having an analog voltage waveform with a peak amplitude of at least twice the input voltage.

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.

Zero-power wake-up sensing circuit in piezoelectric haptic feedback

A method for reducing switching losses and waveform distortion in a driver for a circuit with a capacitive load includes generating a variable pre-drive pulse to achieve zero voltage and zero-current switching of a high-side switch of the unfolding stage. A controller computes the variable pre-drive pulse with the controller, and a sense resistor in series with the power converter inductor detects a zero voltage switching condition point and/or a zero voltage switching condition point. The driver includes a power converter that receives an input voltage vas input and generates a clean folded waveform as an output. An unfolding stage referenced to vreceives the clean folded waveform from the converter and unfolds the folded waveform into a full waveform.

Method for reducing losses and distortion in a driver with a capacitive load

A driver for a circuit with a capacitive load is configured for coupling to a voltage source which provides a DC input voltage, and is configured to generate an output voltage at an output. The driver includes a bidirectional synchronous power converter with a first switch, a second switch, and an inductive device connected to the first and/or second switch. A controller is configured to control the first switch and the second switch. The bidirectional synchronous power converter generates a switching voltage from the input voltage at a switching node and generates the output voltage having an analog voltage waveform with a peak amplitude of at least twice the input voltage. The bidirectional synchronous power converter includes a boost-buck converter configured to generate the analog voltage waveform from the input voltage by transferring increments of energy to the capacitive load in a forward-boost mode and from the load in a reverse-buck mode.

A single ended n-bit hybrid digital-to-analog converter is configured to receive as an input an analog signal and produce an n-bit digital output. The converter includes a split main sub-digital-to-analog converter capacitor array, a most significant bit capacitor array, and a main capacitor array. A coupling capacitor couples the main array to the split main sub-digital-to-analog convert.

Area efficient single-ended analog-to-digital converter

A single die driver integrated circuit is coupled to an input portion having a single inductor receiving a low voltage source and configured to drive a capacitive load with an output voltage. The driver includes a bidirectional synchronous power converter stage configured to generate a switching voltage from the input portion at a switching node and to generate a high voltage waveform from the low-voltage source. An embedded controller is configured to control a switch of the power converter stage.

Highly integrated high voltage actuator driver

A driver for a circuit with a capacitive load, is disclosed, including an input stage, a bi-directional power converter, and a controller to control the driver. The power converter includes an inductive device and two switches configured to receive a DC input voltage vfrom the input stage and generate an analog output waveform having an amplitude greater than vproviding an output distortion below 5% without an output low-pass filter.

Growing community of inventors

Magog, Canada

Simon Chaput